JP2003297590A - Discharge lamp lighting device, light source device, and projection display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable a discharge lamp to be lit including a case where the discharge lamp is at a high temperature, for example, in a case where the discharge lamp is turned on immediately after being turned off. Extend life. SOLUTION: A means 7 for supplying an ignition voltage to a discharge lamp 11 includes a capacitor C2 for charging the supplied voltage, a transformer T2 for boosting the charging voltage of the capacitor C2 and supplying the boosted voltage to the discharge lamp 11, and a capacitor. A charge voltage of the capacitor C2 when the switch element Q2 switches so as to supply a voltage from the capacitor C2 to the transformer T2, including a switch element Q2 for switching whether to supply a voltage from the C2 to the transformer T2, and a thermistor R3. Is changed according to the resistance value of the thermistor R3, so that when the discharge lamp 11 is at a high temperature, an ignition voltage having a higher voltage level than at a normal temperature is supplied to the discharge lamp 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device, a light source device, a liquid crystal projector using a discharge lamp as a light source, and more particularly to a device having improved lighting performance.

[0002]

2. Description of the Related Art In a liquid crystal projector, a discharge lamp is generally used as a light source for illuminating a liquid crystal panel.

As is well known, a discharge lamp is a tube or a spherical glass in which a high-pressure gas is sealed, and a high-voltage pulse (ignition voltage) for discharge is supplied to ionize the gas and a driving current is supplied. By doing so, a current constantly flows in the ionized gas to cause light emission (lighting).

A device for lighting a discharge lamp includes
A circuit (ignition circuit) for generating this ignition voltage and supplying it to the discharge lamp is included. In the conventional discharge lamp lighting device, with this ignition circuit,
An ignition voltage having a fixed voltage level (a voltage level that matches the wattage of the discharge lamp to be lit) is generated and supplied to the discharge lamp (see, for example, Patent Document 1). The igniter 11 corresponds to the ignition circuit, and the igniter 11
Was to produce a fixed voltage level ignition voltage).

FIG. 1 shows a typical structure of an ignition circuit in a conventional discharge lamp lighting device. About 300
The power supply line to which the DC voltage of V is supplied is the resistor R11.
And is grounded via a capacitor C11.

The midpoint of connection between the resistor R11 and the capacitor C11 is connected to one end of the primary winding of the step-up transformer T11 via a discharge element H11 such as a sidac.
The other end of the primary winding of the step-up transformer T11 is grounded.

The secondary winding of the step-up transformer T11 has one end grounded and the other end connected to one end of the primary-side winding of the step-up transformer T12 via a diode D11 and a discharge gap H12. Diode D11 and discharge gap H
The midpoint of connection with 12 is grounded via a capacitor C12. The other end of the secondary winding of the step-up transformer T12 is
It is grounded.

The discharge lamp 110 is attached to the discharge lamp lighting device so that one of the two electrodes is connected to one end of the secondary winding of the step-up transformer T12.

Further, a signal line for supplying an AC drive current from a full bridge (not shown) to the discharge lamp 110 is
It is connected to the secondary winding of the step-up transformer T12.

In this ignition circuit, a DC voltage of about 300 V from the power supply line is charged in the capacitor C11 through the resistor R11. And the capacitor C
When the charging voltage of 11 reaches the discharge starting voltage of the discharging element H11, the voltage is supplied from the capacitor C11 to the primary side of the step-up transformer T11 via the discharging element H11, and the voltage boosted on the secondary side of the step-up transformer T11. Is the diode D1
1 to charge the capacitor C12.

When the charge voltage of the capacitor C12 reaches the discharge start voltage of the discharge gap H12, a voltage pulse is supplied from the capacitor C12 to the primary side of the step-up transformer T12 and boosted at the secondary side of the step-up transformer T12. The voltage pulse is used as the ignition voltage in the discharge lamp 11.
Supplied to zero.

In this way, the ignition voltage having a fixed voltage level determined by the discharge starting voltage of the discharge gap H12 is supplied to the discharge lamp 110.

[0013]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-366791 (paragraph numbers 0014 and 0021, FIG. 1)

[0014]

However, supplying the ignition voltage of such a fixed voltage level to the discharge lamp has the following disadvantages.

When the liquid crystal projector has been used for a long time and then turned off once and then turned on again (for example, immediately after the liquid crystal projector is used in a certain room, it is carried to the next room for use). In such a case, the discharge lamp is hot.

When the temperature of the discharge lamp is high, the pressure of the gas filled in the glass of the discharge lamp rises. Therefore, if the ignition voltage having a voltage level higher than that at room temperature is not supplied to the discharge lamp, the discharge lamp is lit. Can not do it.

Therefore, when the voltage level of the ignition voltage is fixed to a voltage level low enough to light the discharge lamp at room temperature, the discharge lamp does not light at high temperature of the discharge lamp. As a result, after the LCD projector has been used for a long time, the image is not projected even if the power is turned off and then turned on again immediately, and the user has to inconvenience that the user has to wait until the temperature of the discharge lamp drops. Will be done.

On the other hand, when the voltage level of the ignition voltage is fixed to the high voltage level required to light the discharge lamp at high temperature, the ignition voltage of unnecessarily high voltage level is supplied at room temperature. This will deteriorate the electrodes of the discharge lamp and shorten the life of the discharge lamp.

In view of the above points, the object of the present invention is to enable the discharge lamp to be lit even when the temperature of the discharge lamp is high.
An object of the present invention is to provide a lighting device for a discharge lamp, a light source device, and a projection type display device, which can be easily lit regardless of the temperature of the discharge lamp and can prolong the life of the discharge lamp.

[0020]

The present applicant has found that a discharge pulse supply means for supplying a high voltage pulse (ignition voltage) for discharge to a discharge lamp, a means for supplying a drive current to the discharge lamp, and the discharge lamp. The present invention proposes a discharge lamp lighting device including a detection means for detecting a temperature derived from the heat generation of the device and a control means for changing the voltage level of the ignition voltage according to the detection result of the detection means.

In this discharge lamp lighting device, the temperature resulting from the heat generation of the discharge lamp is detected by the detection means, and the voltage level of the ignition voltage is changed by the control means according to the detection result.

By changing the voltage level of the ignition voltage according to the temperature resulting from the heat generation of the discharge lamp in this way, when the discharge lamp is at a high temperature, the ignition of a high voltage level necessary for lighting the discharge lamp at a high temperature is performed. It is possible to supply a voltage to the discharge lamp, while at the room temperature of the discharge lamp, an ignition voltage of a voltage level low enough to light the discharge lamp at room temperature can be supplied to the discharge lamp.

As a result, the discharge lamp lights up when the temperature of the discharge lamp is high, and an ignition voltage of an unnecessarily high voltage level is supplied to the discharge lamp when the temperature of the discharge lamp is at room temperature, so that the discharge lamp is driven by the high voltage. Since the degree of electrode deterioration is reduced, the life of the discharge lamp is extended.

In this discharge lamp lighting device,
As an example, the discharge pulse supply means includes a capacitor for charging the supplied voltage and a transformer for boosting the charging voltage of the capacitor and supplying the boosted voltage to the discharge lamp.
The control means has a switch element for switching whether to supply a voltage from the capacitor to the transformer by an output from the thermistor or the posistor, and when the switch element is switched so as to supply the voltage from the capacitor to the transformer. The voltage level of the charging voltage of this capacitor changes according to the resistance value of this thermistor or posistor, and it is preferable that this thermistor or posistor also serves as the above-mentioned detection means and control means. is there.

Thus, the voltage level of the ignition voltage can be changed according to the temperature derived from the heat generation of the discharge lamp by simply adding a simple circuit such as a thermistor, a posistor or a switch element in the ignition circuit. Become.

Next, the applicant of the present invention detects a discharge lamp, a means for supplying an ignition voltage to the discharge lamp, a means for supplying a driving current to the discharge lamp, and a temperature resulting from heat generation of the discharge lamp. There is proposed a light source device comprising: a detection means for controlling the ignition voltage and a control means for changing the voltage level of the ignition voltage according to the detection result of the detection means. Here, the light source device means a device in which a discharge lamp and a discharge lamp lighting device are integrated.

According to this light source device, the discharge lamp is lit when the temperature of the discharge lamp in the light source device is high, as in the discharge lamp lighting device according to the present invention.
The life of the discharge lamp is extended.

Next, in the projection type display device using the discharge lamp as a light source, the present applicant has a means for supplying an ignition voltage to the discharge lamp, a means for supplying a driving current to the discharge lamp, and the discharge. A projection type display device is proposed which includes a detection means for detecting a temperature resulting from heat generation of a lamp and a control means for changing a voltage level of the ignition voltage according to a detection result of the detection means.

According to this projection type display device, the discharge lamp is turned on even when the power of the projection type display device is turned on when the temperature of the discharge lamp is high, just like the discharge lamp lighting device according to the present invention. Therefore, after the projection type display device is used for a long time, the image is immediately projected when the power is turned off and then the liquid projection type display device is turned on. The usability of the display device is improved. At the same time, the life of the discharge lamp is extended.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION An example in which the present invention is applied to a liquid crystal projector will be specifically described below with reference to the drawings.

FIG. 2 shows the entire structure of the discharge lamp lighting device provided in the liquid crystal projector to which the present invention is applied and its peripheral portion. The liquid crystal projector has a discharge lamp 1.
1 is a device for displaying an image by projecting the image light obtained by irradiating the liquid crystal panel (not shown) with light emitted from the display device 1 and modulating the liquid crystal panel based on an image signal by a projection lens (not shown). In this discharge lamp lighting device 1, about 370
The DC voltage of V is supplied to the down converter 3.

The down converter 3 is a step-down switching power supply, and the DC voltage is a frequency determined by the controller 4 (a frequency within the range of 50 to 100 kHz).
After switching, the voltage is reduced by smoothing.

The controller 4 turns on the discharge lamp 11 (immediately after the liquid crystal projector is powered on).
Determines the switching frequency to a frequency that reduces the switching frequency to about 300 V (a voltage required to generate a high voltage pulse in an ignition circuit 7 described later).

After the discharge lamp 11 is turned on, the controller 4 sets the switching frequency to the discharge lamp 11
50-100 as a sufficient voltage to maintain the lighting of
The frequency is determined to be reduced to V.

The DC voltage output from the down converter 3 is supplied to the full bridge 5. Full bridge 5,
The DC voltage from the down converter 3 is supplied to the controller 6
It is converted into an alternating current (driving current of the discharge lamp 11) having a frequency determined by.

FIG. 3 shows a circuit configuration of the controller 6. The power supply line of the power supply Vcc is the resistor R32 (100
kΩ) and a resistor R33 (100 kΩ). The middle point of connection between the resistors R32 and R33 is OP
It is connected to the + (plus) input terminal of the amplifier 21.

The output terminal of the OP amplifier 21 is a resistor R31.
(100 kΩ) and the capacitor C31 (0.1 μF) are grounded. Resistor R31 and capacitor C3
The midpoint of connection with 1 is connected to the- (minus) input terminal of the OP amplifier 21. The output signal of the OP amplifier 21 is
It is supplied to the full bridge 5 through the output terminal 22.

The midpoint of connection between the resistors R32 and R33 is also connected to the collector of the transistor Q1 via the resistor R34 (10 kΩ). The emitter of the transistor Q1 is grounded.

As shown in FIG. 2, the controller 6 includes
When the liquid crystal projector is powered on, a signal s for turning on the transistor Q1 is supplied for several seconds (for example, 2 seconds) from the timer circuit 12 of the control system in the liquid crystal projector. As shown in FIG. 3, the signal s is supplied to the base of the transistor Q1 through the input terminal 23 of the controller 6.

In this controller 6, the resistance value of the resistor R31 and the electrostatic capacitance of the capacitor C31 are constants that determine the fundamental frequency. The output waveform of the OP amplifier 21 (that is, the output waveform of the full bridge 5) when the transistor Q1 is off is determined by these values and the resistance values of the resistors R32 and R33.

FIG. 4B shows the waveform of the AC drive current output from the full bridge 5 when the transistor Q1 is off. The output waveform at this time is a symmetrical waveform with a frequency of about 170 Hz (the positive period and the negative period are equal).

On the other hand, when the transistor Q1 is turned on, the potential at the midpoint of connection between the resistors R32 and R33 (that is, OP
By changing the potential of the + input terminal of the amplifier 21,
As shown in FIG. 4C, the output waveform of the full bridge 5 changes to an asymmetric waveform in which the frequency becomes lower than that when the transistor Q1 is off and the positive period is significantly longer than the negative period.

In the controller 6, the resistor R34
The circuit portion excluding the transistor Q1 has the same configuration as the controller used for determining the frequency of the AC drive current in the conventional AC drive type discharge lamp lighting device, and the waveform of FIG. The waveform is the same as the waveform of the AC drive current in the AC drive type discharge lamp lighting device.

Therefore, the controller 6 controls the resistor R
It is possible to change the waveform of the AC drive current to an asymmetrical waveform that is significantly longer than the period in which the positive period becomes negative by simply adding the circuit of 34 and the transistor Q1 to the conventional controller. There is.

As shown in FIG. 2, the output of the full bridge 5 is sent to the ignition circuit 7. In addition, the output voltage and output current of the full bridge 5 are respectively the voltage detection circuit 8,
It is detected by the current detection circuit 9, and the output power of the full bridge 5 is detected by the power detection circuit 10 from these detection results. A signal indicating the detection result of the power detection circuit 10 is sent to the controller 4 described above.

FIG. 5 shows a circuit configuration of an ignition circuit 7 which is one of the embodiments of the present invention. A power supply line to which a DC voltage is supplied from the down converter 3 via the full bridge 5 is grounded via a resistor R1 (18 kΩ) and a capacitor C1 (0.022 μF).

At the midpoint of connection between the resistor R1 and the capacitor C1, a winding ratio of 3: is set via a discharge element H1 such as a sidac.
It is connected to one end of the primary winding of the step-up transformer T1. The discharge starting voltage of the discharge element H1 is about 200V. The other end of the primary winding of the step-up transformer T1 is
It is grounded.

One end of the secondary winding of the step-up transformer T1 is grounded, and the other end is wound via the diode D1 with a winding ratio of 1: 2.
It is connected to one end of the primary winding of the 0 step-up transformer T2. The other end of the primary winding of the step-up transformer T2 is connected to the anode of the three-terminal thyristor Q2. The cathode of the three-terminal thyristor Q2 is grounded.

A connection midpoint a between the diode D1 and the step-up transformer T2 is grounded via a capacitor C2 (0.047 μF). Further, the connection midpoint b between the diode D1 and the step-up transformer T2 (that is, the connection midpoint closer to the step-up transformer T2 than the connection midpoint grounded via the capacitor C2) is a resistor R2 (300 kΩ) and a thermistor R3. Grounded through.

The thermistor R3 has a negative temperature coefficient of resistance. For example, the resistance value is about 20 kΩ at room temperature, whereas the thermistor R3 has a high temperature such as the temperature near the discharge lamp 11 immediately after being lit for a long time. At (60 to 80 ° C.), the resistance value becomes about 10 kΩ.

The connection midpoint P between the resistor R2 and the thermistor R3 is connected to the gate of the three-terminal thyristor Q2 via a discharge element H3 such as a sidac. Discharge element H3
The discharge starting voltage is about 10 to 20V. The midpoint of connection between the discharge element H3 and the three-terminal thyristor Q2 is grounded via a resistor R4 for noise suppression at the gate of the three-terminal thyristor Q2.

The discharge lamp 11 is the discharge lamp lighting device 1
By mounting it on one side, one of the two electrodes is connected to one end of the secondary winding of the step-up transformer T2.

The signal line for supplying the AC driving current from the full bridge 5 to the discharge lamp 11 is connected to the secondary winding of the step-up transformer T2.

Of the grounding points of the ignition circuit 7, from the grounding point of the secondary winding of the step-up transformer T1 to the grounding point of the primary side winding of the step-up transformer T2, as seen from the left side of FIG. It is insulated from the grounding point.

In this ignition circuit 7, when the discharge lamp 11 is turned on (immediately after the power of the liquid crystal projector is turned on), a DC voltage of about 300 V from the down converter 3 is charged in the capacitor C1 through the resistor R1. . Then, the charging voltage of the capacitor C1 changes to the discharge element H1.
When the discharge starting voltage is reached, the voltage is supplied from the capacitor C1 to the primary side of the step-up transformer T1 via the discharge element H1, and the voltage boosted to 10/3 times on the secondary side of the step-up transformer T1 is supplied to the diode D1. Through which the capacitor C2 is charged.

When the voltage at the connection midpoint P between the resistor R2 and the thermistor R3 due to the charging voltage of the capacitor C2 reaches the discharge starting voltage of the discharging element H3, the voltage is discharged from the discharging element H3 to the gate of the three-terminal thyristor Q2. Since the three-terminal thyristor Q2 is turned on by being supplied, a voltage pulse is supplied from the capacitor C2 to the primary side of the step-up transformer T2, and the voltage pulse boosted 20 times on the secondary side of the step-up transformer T2 is ignited. The voltage is supplied to the discharge lamp 11.

The frequency of the ignition voltage supplied from the ignition circuit 7 to the discharge lamp 11 (that is, the repetition frequency of the ignition pulse) is about 30 Hz.

Further, the ignition circuit 7 is arranged at a position that correlates with a change in ambient temperature due to heat generation of the discharge lamp 11, for example, near the side surface of the discharge lamp 11 housed in the lamp holder. As the resistance rises, the resistance value of the thermistor R3 decreases from about 20 kΩ to about 10 kΩ. Therefore, at high temperature, the voltage at the connection midpoint P becomes about half that at room temperature.

Therefore, in the ignition circuit 7, at high temperature, the charging voltage of the capacitor C2 when the voltage at the connection midpoint P reaches the discharge start voltage of the discharge element H3 is about twice as high as at room temperature. An ignition voltage having a voltage level about twice as high as that at the time is supplied to the discharge lamp 11.

The voltage level of the ignition voltage at room temperature is high enough to turn on the discharge lamp 11 at room temperature. Further, the voltage level of the ignition voltage at the time of high temperature is high enough to light the high temperature discharge lamp 11 immediately after lighting for a long time.

Next, the lighting operation of the discharge lamp 11 in this liquid crystal projector is divided into a common operation at normal temperature and high temperature of the discharge lamp 11 and a different operation at normal temperature and high temperature of the discharge lamp 11. Explain.

[Common Operation at Normal Temperature and High Temperature] Immediately after the user turns on the power of the liquid crystal projector, the transistor s of the controller 6 of the discharge lamp lighting device 1 is activated by the signal s from the timer circuit 12 (FIG. 2). Since Q1 (FIG. 3) is turned on, as shown in FIG. 4C, an AC drive current having an asymmetric waveform in which the positive period is significantly longer than the negative period is supplied to the discharge lamp 11.

Immediately after turning on the power of the liquid crystal projector, the ignition voltage is supplied to the discharge lamp 11 based on the DC voltage of about 300 V supplied from the down converter 3 to the ignition circuit 7 via the full bridge 5. .

FIG. 4A shows the waveform of the ignition voltage of the discharge lamp 11 at room temperature on the same timing scale as in FIGS. 4B and 4C.

Here, the waveform of the AC drive current becomes positive and the waveform of the ignition voltage becomes positive at the timing when the waveform of the AC drive current remains positive for a certain period of time thereafter (that is, in the discharge lamp). In the case where the gas is ionized), the AC driving current in the positive direction is supplied for a certain period of time or more, so that a current constantly flows in the ionized gas, and the discharge lamp is turned on.

On the other hand, when the waveform of the ignition voltage becomes positive at the timing when the waveform of the AC drive current becomes negative, the discharge lamp does not light.

Further, even if the waveform of the AC drive current is positive but the waveform of the ignition voltage becomes positive immediately after the waveform of the AC drive current turns negative, the discharge lamp does not light up.

As described above, whether or not the discharge lamp is turned on is determined by the timing when the waveform of the ignition voltage becomes positive.

In the discharge lamp lighting device 1,
As shown in FIG. 4, the waveform of the AC drive current is positive at all timings t1 to t5 when the waveform of the ignition voltage is positive, and thereafter the waveform of the AC drive current is positive for a certain period of time or longer. Is maintained. Therefore, the probability that the ignition voltage waveform becomes positive at the timing when the discharge lamp is turned on is considerably high.

Although the ignition voltage at room temperature is shown in FIG. 4A, the ignition voltage at high temperature of the discharge lamp 11 is exactly the same because the AC drive current has an asymmetric waveform as shown in FIG. 4C. , The probability that the ignition voltage waveform becomes positive at the timing when the discharge lamp is turned on becomes considerably high.

By the way, when the transistor Q1 of the controller 6 is off, the AC driving current having a waveform as shown in FIG. 4B is supplied to the discharge lamp 11, and this waveform has a conventional AC driving type discharge lamp lighting. The waveform is similar to the AC drive current in the device.

If the AC drive current having the waveform as shown in FIG. 4B is supplied to the discharge lamp 11 immediately after the liquid crystal projector is powered on, the waveform of the AC drive current is positive and after that, a certain time or more. It is only at the timing t5 in FIG. 4 that the waveform of the ignition voltage becomes positive at the timing at which the waveform of the AC drive current remains positive. That is, the waveform of the AC drive current is negative at the timings t1 and t3, and
At t4, the waveform of the AC drive current is positive, but it immediately turns negative. Therefore, the probability that the waveform of the ignition voltage becomes positive at the timing when the discharge lamp 11 is turned on becomes considerably low.

If the probability of lighting the discharge lamp 11 is low as described above, the ignition voltage must be supplied for a long time before the discharge lamp 11 lights. Therefore, the discharge lamp 11 is turned on after the power is turned on. It takes time to turn on (the image starts to be projected).

Further, for example, if the discharge lamp 1 does not light up even if the ignition voltage is continuously supplied for several seconds after the power of the liquid crystal projector is turned on, the supply of the ignition voltage is automatically interrupted. If so, the user is inconvenient to either wait for the ignition voltage supply to be resumed or to cycle power.

In order to eliminate such a conventional inconvenience, in this liquid crystal projector, immediately after the power is turned on, the AC drive current having a symmetrical waveform is changed to an asymmetric waveform having a positive period longer than a negative period. By supplying the converted AC drive current to the discharge lamp 11, the probability that the waveform of the ignition voltage becomes positive at the timing when the discharge lamp 11 is turned on is considerably increased.

As a result, the discharge lamp 11 is turned on in a short time after the power is turned on (that is, within a few seconds while the transistor Q1 in the controller 6 is turned on almost certainly by the signal s from the timer circuit 12). Then, the image is projected. Therefore, the usability of the liquid crystal projector is improved for the user.

Further, the ignition voltage is set to the discharge lamp 1
1 is shortened, the degree of deterioration of the electrodes of the discharge lamp 11 due to high voltage is reduced, so that the life of the discharge lamp 11 is extended.
Therefore, it is possible for the user to request the aftercare for the replacement of the discharge lamp 11 less frequently, and
The running costs of LCD projectors have been reduced.

Moreover, these effects can be obtained only by using the controller 6 in which the simple circuit of the resistor R34 and the transistor Q1 is added to the conventional controller as described above.

[Different operation at normal temperature and high temperature] When the power of the liquid crystal projector is turned on after a considerable time has passed since the liquid crystal projector was last used, since the discharge lamp 11 is at normal temperature, the discharge lamp 11 The temperature of the thermistor R3 of the ignition circuit 7, which is in the vicinity of, also becomes normal temperature.

On the other hand, when the liquid crystal projector is turned off once after being used for a long time and then immediately turned on again (for example, immediately after the liquid crystal projector is used in one room, the liquid crystal projector is placed in the next room). In the case of carrying it for use), since the discharge lamp 11 generates heat and becomes high in temperature, the thermistor R3 also becomes high in temperature.

Therefore, when the temperature of the discharge lamp 11 is high, the ignition voltage having a voltage level about twice that at room temperature is supplied to the discharge lamp 11.

When the temperature of the discharge lamp 11 is high, the pressure of the gas filled in the glass of the discharge lamp 11 rises. Therefore, unless the ignition voltage of a voltage level higher than that at room temperature is supplied to the discharge lamp 11, 11 cannot be turned on.

In this discharge lamp lighting device 1, when the discharge lamp 11 is at a high temperature, the ignition voltage having a higher voltage level than that at the normal temperature is supplied to the discharge lamp 11. Therefore, after the liquid crystal projector is used for a long time, the power is turned off once. Immediately after the liquid crystal projector is turned on again, the discharge lamp 11 is turned on.

Further, at room temperature of the discharge lamp 11, the ignition voltage of a relatively low voltage level is generated.
However, at room temperature, the discharge lamp 11 is sufficiently lit even at such a low voltage level of the ignition voltage.

In the conventional AC drive type discharge lamp lighting device, the voltage level of the ignition voltage is fixed. However, when the fixed voltage level is low, the discharge lamp does not light when the discharge lamp is at a high temperature (in other words, when the discharge lamp is at a high temperature). ,
(You have to wait until the temperature of the discharge lamp drops)
When the fixed voltage level is high, there is a disadvantage that the life of the discharge lamp is shortened by supplying an ignition voltage of an unnecessarily high voltage level at room temperature of the discharge lamp. It was

In this liquid crystal projector, in order to eliminate such a conventional inconvenience, the voltage level of the ignition voltage is changed according to the temperature derived from the heat generation of the discharge lamp 11, so that when the discharge lamp 11 is at a high temperature,
The ignition voltage having a high voltage level required to light the discharge lamp 11 at a high temperature is supplied to the discharge lamp 11, while the discharge lamp 11 has a low voltage level enough to light the discharge lamp 11 at a normal temperature when the discharge lamp 11 has a normal temperature. Ignition voltage is supplied to the discharge lamp 11.

As a result, even after the liquid crystal projector has been used for a long time, the power is turned off once, and then the power is turned on again, the discharge lamp 1 is immediately turned on.
1 is turned on and an image is projected. Therefore, also in this respect, the usability of the liquid crystal projector is improved for the user.

Further, the ignition voltage of an unnecessarily high voltage level is applied to the discharge lamp 11 at room temperature 11 at room temperature.
Discharge lamp 11 due to high voltage
Since the degree of deterioration of the electrodes of the
The life of 1 is extended. Therefore, also in this respect, the frequency of the user's requesting aftercare for the replacement of the discharge lamp 11 can be reduced, and the running cost of the liquid crystal projector can be reduced.

Moreover, by simply adding a simple circuit such as the thermistor R3, the three-terminal thyristor Q2, and the discharge element H3 in place of the discharge gap in the ignition circuit, the voltage of the ignition voltage can be changed according to the temperature caused by the heat generation of the discharge lamp 11. You can change the level.

In the above example, as shown in FIGS. 4B and 4C, the controller 6 reduces the frequency of the waveform of the AC drive current output from the full bridge 5 when the discharge lamp is turned on. At the same time, the asymmetrical waveform is changed so that the positive period is longer than the negative period.

However, as another example, when the discharge lamp is turned on, the waveform of the AC drive current output from the full bridge 5 is maintained at a constant frequency, and the positive period is less than the negative period. It may be changed to a long asymmetric waveform.

Further, in the above example, when the discharge lamp 11 is turned on, the waveform of the AC drive current is changed to an asymmetrical waveform so that the ignition voltage waveform becomes positive at the timing when the discharge lamp 11 is turned on. The probability is high.

However, as another example, when the discharge lamp 11 is turned on, the AC drive current is synchronously controlled with respect to the ignition voltage (that is, the waveform of the AC drive current changes at a timing when the waveform of the ignition voltage becomes positive). Even if the probability that the waveform of the ignition voltage becomes positive at the timing when the discharge lamp 11 is turned on is increased by controlling the waveform of the AC drive current to be positive and maintaining a positive waveform for a certain period of time after that). Good.

Further, in the above example, the thermistor having the ratio of the resistance value at the time of high temperature to the resistance value at the room temperature of about 1: 2 is provided in the ignition circuit 7, but this ratio is not about 1: 2. A thermistor may be provided.

In the above example, as shown in FIG. 5, the midpoint of connection between the diode D1 and the step-up transformer T2 is grounded via the resistor R2 and the thermistor R3. However, as another example, this midpoint of connection is grounded through a posistor and a resistor having a positive temperature coefficient of resistance,
The midpoint of connection between the posistor and the resistor may be connected to the gate of the three-terminal thyristor Q2 via the discharge element H3 of FIG.

FIG. 6 shows a modified example of the configuration of the ignition circuit 7 having such a configuration, and the portions common to FIG. 5 are designated by the same reference numerals. In this example, the connection midpoint b between the diode D1 and the step-up transformer T2 is grounded via a posistor R22 and a resistor R23 (20 kΩ).

The posistor R22 has a positive temperature coefficient of resistance. For example, the posistor R22 has a resistance value of about 300 kΩ at room temperature, but has a high temperature such as a temperature near the discharge lamp 11 immediately after being lit for a long time. At (60 to 80 ° C.), the resistance value becomes about 600 kΩ.

The connection midpoint P between the posistor R22 and the resistor R23 is connected to the gate of the three-terminal thyristor Q2 via the discharge element H3.

In the ignition circuit of FIG. 6 also, the posistor R2 and the resistor R3 depending on the charging voltage of the capacitor C2.
When the voltage at the connection midpoint P of the three-terminal thyristor Q3 reaches the discharge start voltage of the discharge element H3, the voltage is supplied from the discharge element H3 to the gate of the three-terminal thyristor Q2.
2, the voltage pulse is supplied from the capacitor C2 to the primary side of the step-up transformer T2, and the step-up transformer T2 is turned on.
The voltage pulse boosted 20 times on the secondary side of 2 is supplied to the discharge lamp 11 as an ignition voltage.

Then, as the temperature rises, the resistance value of the posistor R2 increases from about 300 kΩ to about 600 kΩ, so that the voltage at the connection midpoint P is about half that at room temperature at high temperature. .

Therefore, at a high temperature, the charging voltage of the capacitor C2 when the voltage at the connection midpoint P reaches the discharge starting voltage of the discharge element H3 is about twice as high as that at room temperature. The ignition voltage having the voltage level of is supplied to the discharge lamp 11.

Further, in the above example, as shown in FIG. 5, the ignition circuit 7 is provided with means for detecting the temperature resulting from the heat generation of the discharge lamp 11 and the voltage level of the ignition voltage according to the detection result. A thermistor R3 is provided as an element that also serves as a means for changing (that is, changing the voltage at the connection middle point P).

However, as another example, this thermistor R
A resistor is provided at the position of 3, and the temperature derived from the heat generation of the discharge lamp 11 is detected by a temperature sensor. When the temperature detected by this temperature sensor is high, another resistor is connected in parallel to this resistor. By doing so, the voltage at the connection midpoint P may be lowered.

Alternatively, a variable resistor is provided at the position of the thermistor, and the temperature resulting from the heat generation of the discharge lamp 11 is detected by a temperature sensor. When the temperature detected by this temperature sensor is high, this variable resistor is detected. The voltage at the connection midpoint P may be lowered by reducing the resistance value of the.

Further, in these cases, the temperature sensor is
It does not necessarily have to be provided in the ignition circuit 7 or the discharge lamp lighting device 1. For example, in the vicinity of the exhaust fan in the liquid crystal projector, in the vicinity of the exhaust port (heat dissipation port) of the liquid crystal projector, or in the inner wall of the cabinet of the liquid crystal projector. As described above, the liquid crystal projector may be provided at an appropriate place where the temperature resulting from the heat generation of the discharge lamp 11 can be detected.

In the above example, as shown in FIG. 5, the ignition circuit 7 increases the voltage supplied from the capacitor C2 to the primary side of the step-up transformer T2 when the discharge lamp 11 has a high temperature. The ignition voltage level is raised.

However, as another example, when the temperature of the discharge lamp 11 is high, the voltage level of the ignition voltage may be increased by increasing the step-up ratio in the step-up transformer T2.

FIG. 7 shows an example in which the configuration of the portion subsequent to the diode D1 in the ignition circuit 7 of FIG. 5 is changed so as to increase the step-up ratio of the step-up transformer T2 at high temperature. The same parts as 5 are given the same reference numerals.

In this modification, the discharge gap H2 is interposed between the diode D1 and the primary side of the step-up transformer T2, and the midpoint of connection between the diode D1 and the discharge gap H2 is grounded via the capacitor C2. ing. The discharge starting voltage of the discharge gap H2 is about 800V to 1kV.

The collector of the transistor Q3 is connected to the middle of the primary winding of the step-up transformer T2.
The emitter of the transistor Q3 is grounded, and the base of the transistor Q3 is connected to the output terminal of the comparator 31.

The temperature derived from the heat generation of the discharge lamp 11 is detected by a temperature sensor (not shown), and a signal indicating the detection result is input to one input terminal of the comparator 31. A signal Ref indicating a temperature equal to or higher than room temperature is input to the other input terminal of the comparator 31 as a reference temperature.

When the detection result is higher than the reference temperature, the output signal from the comparator 31 is the transistor Q.
3 is supplied to the base of transistor Q3.
Turns on. Therefore, at this time, the step-up transformer T2
The step-up ratio of is the ratio between the number of turns in the primary winding of the step-up transformer T2, which is closer to the discharge gap H2 than the connection point with the transistor Q3, and the secondary side winding of the step-up transformer T2. (Greater than 1:20).

As a result, when the discharge lamp 11 is at a high temperature,
Since the step-up ratio of the step-up transformer T2 becomes large, the voltage level of the ignition voltage becomes high.

Further, in the above example, the present invention is applied to a liquid crystal projector provided with a discharge lamp lighting device for supplying an AC drive current to the discharge lamp. However, the point of increasing the voltage level of the ignition voltage when the discharge lamp is at a high temperature may be applied to a liquid crystal projector provided with a discharge lamp lighting device that supplies a DC drive current to the discharge lamp.

Further, although the present invention is applied to the liquid crystal projector in the above example, a projection type using a light valve other than the liquid crystal projector, for example, a liquid crystal panel such as DMD (Digital Micro mirror Device). The present invention may be applied to a display device. Furthermore, the present invention may be applied to the discharge lamp lighting device itself or a light source device in which the discharge lamp and the discharge lamp lighting device are integrated.

Further, the present invention is not limited to the above examples, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0117]

As described above, according to the present invention, by changing the voltage level of the ignition voltage according to the temperature derived from the heat generation of the discharge lamp, the discharge lamp is lit at a high temperature when the discharge lamp is at a high temperature. To supply the ignition voltage of a high voltage level necessary for the discharge lamp to the discharge lamp, on the other hand, at room temperature of the discharge lamp, supply the ignition voltage of a voltage level low enough to light the discharge lamp at room temperature. Therefore, it is possible to light the discharge lamp when the temperature of the discharge lamp is high, and it is possible to extend the life of the discharge lamp.

Moreover, the effect that the voltage level of the ignition voltage can be changed according to the temperature derived from the heat generation of the discharge lamp can be obtained only by adding a simple circuit such as a thermistor, a posistor, or a switch element in the ignition circuit. can get.

Further, in particular, according to the projection type display apparatus of the present invention, even when the projection type display apparatus is used for a long time, the power is turned off once and then the liquid projection type display apparatus is turned on again. Since the image will be projected soon,
It is possible to obtain the effect of improving the usability of the projection display device for the user.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an ignition circuit of a conventional discharge lamp lighting device.

FIG. 2 is a diagram showing an overall configuration of a discharge lamp lighting device of a liquid crystal projector to which the present invention is applied and its peripheral portion.

FIG. 3 is a diagram showing a configuration example of a controller 6 in FIG.

FIG. 4 is a waveform diagram showing a relationship between a waveform of an ignition voltage and a waveform of an AC drive current in the discharge lamp lighting device 1 of FIG.

5 is a diagram showing a configuration example of an ignition circuit 7 in FIG.

6 is a diagram showing a modification of the configuration of the ignition circuit 7 of FIG.

7 is a diagram showing a modification of the configuration of the ignition circuit 7 of FIG.

[Explanation of symbols]

1 discharge lamp lighting device, 2 DC power supply, 3 down converter, 4, 6 controller, 5 full bridge, 7 ignition circuit, 8 voltage detection circuit, 9 current detection circuit, 10 power detection circuit,
11 discharge lamp, 12 timer circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/133 535 G02F 1/133 535 5C058 G03B 21/14 G03B 21/14 A H04N 5/74 H04N 5 / 74 A H05B 41/24 H05B 41/24 DF Term (Reference) 2H088 EA12 HA06 HA28 MA20 2H093 NA80 NC42 NC57 ND02 ND60 NE10 NG02 2K103 AA05 AB10 BA02 CA54 CA60 3K072 AA11 AC01 AC11 BA05 BC05 CB06 DA00 DD08 DE02 DE04 DE04 DE02 DE04 DE04 DE04 HA03 HA10 3K083 AA06 AA07 AA45 BA04 BA25 BA26 BA33 BC13 BC17 BC19 BC37 BC42 BC47 BD03 BD04 BD16 BD22 BD25 BE05 BE23 BE24 CA32 5C058 AB03 BA29 EA01 EA02 EA51

Claims (9)

[Claims] 1. A discharge pulse supply means for supplying a high voltage pulse for discharge to a discharge lamp, a drive current supply means for supplying a drive current to the discharge lamp, and a temperature derived from heat generation of the discharge lamp. A discharge lamp lighting device comprising: a detection means; and a control means for changing the voltage level of the discharge high voltage pulse according to the detection result of the detection means. 2. The discharge lamp lighting device according to claim 1, wherein the discharge pulse supply means boosts the charging voltage of the capacitor and a capacitor for charging the supplied voltage and supplies the boosted voltage to the discharge lamp. The control means includes a switch element that switches whether to supply a voltage from the capacitor to the transformer according to an output from a thermistor or a posistor whose resistance value changes according to an ambient temperature, The voltage level of the charging voltage of the capacitor when the switching element is switched so as to supply a voltage from the capacitor to the transformer is adapted to change according to the resistance value of the thermistor or posistor, and the thermistor or Discharge lamp lighting, characterized in that the posistor also serves as the detection means and the control means. apparatus. 3. The discharge lamp lighting device according to claim 1, wherein the discharge pulse supply means boosts the charging voltage of the capacitor to charge the supplied voltage and supplies the voltage to the discharge lamp. The control means compares the signal indicating the temperature detected by the detecting means with the signal indicating the reference temperature, and outputs a comparison signal based on the comparison result, and the output of the comparator. And a step-up ratio changing means for changing the step-up ratio of the transformer, the step-up ratio changing means is controlled by the comparison signal from the comparator to change the voltage level of the discharging high-voltage pulse. A discharge lamp lighting device characterized by the above. 4. The discharge lamp lighting device according to claim 1, wherein the drive current supply means supplies an AC drive current, and the AC drive is performed when the high voltage pulse for discharge is supplied. A discharge lamp lighting device, comprising: a waveform converting means for converting a waveform of a current into a waveform in which a positive period is longer than a negative period. 5. A discharge lamp, discharge pulse supply means for supplying a high voltage pulse for discharge to the discharge lamp, drive current supply means for supplying a drive current to the discharge lamp, and heat generation of the discharge lamp. A light source device comprising: a detection unit that detects a temperature; and a control unit that changes the voltage level of the discharge high-voltage pulse according to the detection result of the detection unit. 6. The light source device according to claim 5, wherein the drive current supply unit supplies an AC drive current, and when the high voltage pulse for discharging is supplied, the drive current of the AC drive current is changed. 1. A light source device, comprising: a waveform converting means for converting a waveform into a waveform in which a positive period is longer than a negative period. 7. A projection type display device using a discharge lamp as a light source, comprising: discharge pulse supply means for supplying a discharge high voltage pulse to the discharge lamp; and drive current supply means for supplying a drive current to the discharge lamp. A projection comprising: a detection unit that detects a temperature resulting from heat generation of the discharge lamp; and a control unit that changes a voltage level of the discharge high-voltage pulse according to a detection result of the detection unit. Type display device. 8. The projection type display device according to claim 7, wherein the drive current supply unit supplies an AC drive current, and the AC drive is performed when the discharge high voltage pulse is supplied. A projection type display device comprising a waveform converting means for converting a waveform of a current into a waveform in which a positive period is longer than a negative period. 9. The projection type display device according to claim 7, further comprising a timer for outputting a signal to said waveform converting means for a predetermined period based on an operation signal from a user, wherein said waveform converting means outputs from said timer. When the signal of is output, the waveform of the AC drive current is converted into a waveform whose positive period is longer than negative period,
A projection type display device, wherein when the signal from the timer is not output, the waveform of the AC drive current is converted into a waveform in which a positive period and a negative period are equal.