JP2005267933A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of realizing high-speed modulation of brightness of a light source. <P>SOLUTION: A lamp current detection signal is converted by a lamp current detection signal conversion circuit Ai with a variable gain including a plurality of switches Z0, Z1, etc. of which the on/off states are controlled in response to the true or false of the respective bits of modulation signals M0, M1, etc., by means of a combination of the true and false of the respective bits of the modulation signals M0, M1, etc.: and feedback control is so executed that it coincides with a lamp current target signal St. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp, particularly a high-intensity discharge lamp such as a high-pressure mercury lamp, a metal halide lamp, or a xenon lamp.

For example, a high-intensity discharge lamp (HID lamp) is used in a light source device for an optical device for image display such as a liquid crystal projector or a DLP (TM) projector.
When this type of lamp is lit, a voltage called a no-load open voltage is applied to the lamp, a high voltage is superimposed on the no-load open voltage to cause a dielectric breakdown in the discharge space, and a glow discharge occurs. Transition to arc discharge.

Until now, as a lighting method of the HID lamp, it has been common to light with constant power, that is, with constant brightness.
However, when the displayed image is dark in an optical device for image display, for example, as in the technique described in Japanese Patent Application Laid-Open Nos. 2000-78496 and 2001-27890, image quality and contrast are improved. For that purpose, the discharge lamp lighting device needs to be able to dimm the brightness of the light source in multiple stages according to the signal of the image processing circuit in the optical device, and as the dimming speed, Fast ones are desirable.

  In addition, for example, in the case of a certain type of photoacoustic analyzer, it is necessary to accurately define the temporal change (profile) of the intensity of light irradiated to the subject. In this case, the photoacoustic analyzer There is a need for a light source that can be modulated and that can reproduce a time-varying profile required by the optical waveform generation circuit. As such a light source, for example, a laser and a light modulator are used as in the technique described in JP-A-9-133654. However, in this case, monochromaticity and directivity like a laser are used. Therefore, it is difficult to apply light sources such as high-pressure mercury lamps, metal halide lamps, and xenon lamps at high speed.

The discharge lamp lighting device for the HID lamp compares the amount correlated with the electric power supplied to the lamp with a predetermined “amount correlated with the power target value”, and is feedback-controlled in the direction in which they match. As a result, the target power is achieved.
When dimming the brightness of the light source, the “amount correlated with the power target value” is changed.

Specifically, for example, there is a method of detecting a lamp voltage and a lamp current, calculating a lamp power value by multiplication, and comparing this with a power target value.
At this time, the multiplication operation may be performed on the analog lamp voltage signal and the lamp current signal by using an analog multiplication circuit, or may be performed digitally by an AD converter built-in microprocessor mounted on the discharge lamp lighting device. In some cases, a lamp voltage signal and a lamp current signal are obtained and multiplied in a microprocessor.

Alternatively, for example, as in the technique described in Japanese Patent Application Laid-Open No. 11-283781, a method of comparing the lamp current with the current target value calculated by detecting the lamp voltage and the lamp current and dividing the power target value by the lamp voltage. There is also.
In this case, in order to calculate the current target value, a digital ramp voltage signal is obtained by a microprocessor with a built-in AD converter, and a division operation is performed in the microprocessor.

  Further, for example, as in the technique described in Japanese Patent Laid-Open No. 11-339993, the lamp voltage and the lamp current are detected and multiplied after being configured to increase the resistance value of the lamp current detection resistor during dimming. Some of them are input to a calculator and the output value of the multiplier is compared with a reference value.

  Further, for example, as in the technique described in Japanese Patent Application Laid-Open No. 10-3996, the lamp voltage detecting means for detecting the lamp voltage, the lamp current detecting means for detecting the lamp current, and the voltage dividing action on the outputs of both means There is also a variable voltage dividing means that changes the voltage dividing ratio during the dimming operation and controls the lighting main circuit according to the output of the variable voltage dividing means.

As described above, the reason why the “amount correlated with the power target value” is changed for dimming is that the voltage of the HID lamp has a unique characteristic.
That is, the lamp voltage shows a low value of about 10 V, for example, immediately after the lamp starts and shifts to arc discharge. Thereafter, as the lamp temperature rises, the lamp voltage also increases and eventually enters a steady lighting state. enter.
The voltage in the steady lighting state is generally stable in a short period, but varies in the long term depending on conditions such as electrode wear. For example, a new lamp has a life of about 60 V. It rises to about 140V at the end.
Assuming that the rated power of this lamp is 200 W, for example, the lamp current is about 3.3 A when it is new, and about 1.4 A at the end of its life.

Since the brightness of the light source is proportional to the power supplied to the lamp, the dimming means that the power is reduced to, for example, 80% of the reference power, for example, the rated power. Must be specific and controllable.
However, as described above, since the lamp voltage changes in the HID lamp, when the lamp power is to be modulated for dimming, for example, the power is specified only by specifying the lamp current. Therefore, it is necessary to change the “amount correlated with the power target value”.

However, there are problems that cannot be solved by these conventional techniques.
The first problem is that high-speed dimming, that is, high-speed modulation of the brightness of the light source is difficult. Compared with the above-described amount that correlates with the power supplied to the lamp and a predetermined “amount that correlates with the power target value”, the “power target value” In the case of changing the amount that correlates to the ”, multiplication and division operations are required. Therefore, a high-speed A / D converter or microprocessor or a high-speed analog multiplier or divider is required for high-speed modulation operation. However, there was a disadvantage that the cost increased.

Furthermore, in the case of a system that performs signal processing for dimming by sampling a signal at regular intervals, especially for those that perform AD conversion, multiplication, and division using a microprocessor, signal processing for each sampling period Therefore, even if the dimming request generation circuit cannot control the dimming timing and the timing signal for giving the processing timing is provided, the time until the microprocessor reacts to the timing signal by the interrupt processing However, the timing of dimming cannot be accurately defined because it depends on the processing performed internally.
Therefore, there is a disadvantage that jitter (time direction variation) occurs in the light control profile.
JP 2000-78496 A JP 2001-27890 A JP-A-9-133654 JP-A-11-283787 JP 11-339993 A JP-A-10-3996

  An object of the present invention is to provide a discharge lamp lighting device that realizes high-speed modulation of the brightness of a light source.

  A discharge lamp lighting device according to claim 1 of the present invention is a discharge lamp lighting device for lighting a discharge lamp (Ld) in which a pair of electrodes for main discharge are arranged to face each other, and the discharge lamp (Ld) ), A lamp voltage detection means (Vx) for detecting a lamp voltage (VL) and generating a lamp voltage detection signal (Sv), and a lamp current (IL) to detect a lamp current. Lamp current detection means (Ix) for generating a detection signal (Si), a lamp current detection signal conversion circuit (Ai) for converting the lamp current detection signal (Si), and the lamp current detection signal conversion circuit The power feeding circuit (Ux) so that the difference between the lamp current correlation signal (Sj) from (Ai) and the lamp current target signal (St) indicating the magnitude of the current flowing through the discharge lamp (Ld) is reduced. A power supply capacity control circuit (Ud) for feedback control and a load power value PL applied to the discharge lamp (Ld) depending on the lamp voltage detection signal (Sv) are set to a predetermined target power value PT. A power control circuit (Up) for updating the lamp current target signal (St) and a modulation signal generation circuit (Un) for generating a binary modulation signal (M0, M1,...) Of a plurality of bits, The lamp current detection signal conversion circuit (Ai) includes a plurality of switches (Z0, Z1,...) Whose ON state and OFF state are controlled corresponding to the true and false of each bit of the modulation signal (M0, M1,...). .., And the gain is variable by a combination of true and false of each bit of the modulated signal (M0, M1,...).

  A discharge lamp lighting device according to a second aspect of the present invention is the discharge lamp lighting device according to the first aspect, wherein the power control circuit (Up) is in an inactive state from the start of lighting until the lamp voltage (VL) is stabilized. A modulation generation signal (Ss), and the modulation signal generation circuit (Un) is externally provided as the modulation signals (M0, M1,...) When the modulation permission signal (Ss) is in an active state. A signal equal to the original modulation signal (F0, F1,...) Generated by the original dimming signal generation circuit (Um) is generated. When the modulation permission signal (Ss) is inactive, the modulation signal (M0, M1) is generated. ,...), A signal having a predetermined combination is generated.

  A discharge lamp lighting device according to a third aspect of the present invention is the discharge lamp lighting device according to the second aspect, wherein the power control circuit (Up) generates the original dimming signal outside during a period in which the lamp voltage (VL) is stable. When the current target update permission signal (Sf) generated by the circuit (Um) is in an inactive state, the lamp current target signal (St) is not updated.

  A discharge lamp lighting device according to a fourth aspect of the present invention is the discharge lamp lighting device according to the third aspect, wherein the power control circuit (Up) monitors the duration of the inactive state of the current target update permission signal (Sf). When it is detected that the duration time is equal to or longer than a predetermined time, the modulation permission signal (Ss) is deactivated and the load power value PL applied to the discharge lamp (Ld) is predetermined. The lamp current target signal (St) is updated so as to become the target power value PT.

  The discharge lamp lighting device according to the present invention requires complicated processing such as AD conversion, multiplication and division operations by the microprocessor of the AD converted data, and complex processing such as analog multiplication and division operations. First, the on-state and off-state of each switch (Z0, Z1,...) Are directly controlled by the modulation signal (M0, M1,...). Therefore, the gain of the lamp current detection signal conversion circuit (Ai) is increased. Since it is directly modulated at a high speed, it is possible to provide a discharge lamp lighting device that realizes a high-speed modulation of the brightness of the light source without causing jitter in the dimming profile.

As a unique feature of the HID lamp, in addition to what is described in the background art section, there is a feature that the lamp voltage does not change much even if the lamp current changes.
In other words, the lamp voltage can be regarded as being constant irrespective of the current flowing like a Zener diode.
Of course, the lamp voltage itself that can be regarded as constant as described above is a value determined by the above-described conditions such as the elapsed time after the transition to arc discharge and the state from new to the end of life. Although it is a short-term approximation, the present invention takes advantage of this feature.

Hereinafter, embodiments of the present invention will be described in detail.
First, the form for implementing this invention is demonstrated using FIG. 1 which is the block diagram which simplifies and shows the 1st Example of the discharge lamp lighting device of this invention.
A starter (Ue) for starting the discharge is connected to the discharge lamp (Ld). The starting method in this figure shows a so-called external trigger method in which a high voltage is applied to the trigger electrode (Et) provided outside the envelope of the discharge lamp (Ld). It is irrelevant to the essence of the invention.
The power supply circuit (Ux) is connected to supply power to the discharge lamp (Ld) via the electrodes (E1, E2) for main discharge of the discharge lamp (Ld).

The output current of the power feeding circuit (Ux), that is, the lamp current (IL) is detected by the lamp current detection means (Ix), and a lamp current detection signal (Si) is generated and input to the lamp current detection signal conversion circuit (Ai). And converted into a lamp current correlation signal (Sj) and output.
The lamp current detection signal conversion circuit (Ai) includes a plurality of switches (Z0, Z1,...) Therein (for example, as shown in FIG. 6 to be described later), and is in an on state and an off state. Is an output signal corresponding to the gain of the lamp current detection signal conversion circuit (Ai), that is, the magnitude of the lamp current detection signal (Si) that is an input signal of the lamp current detection signal conversion circuit (Ai). The ratio of the magnitude of the lamp current correlation signal (Sj) is configured to be variable.
Here, corresponding to each of the switches (Z0, Z1,...), Binary modulation signals (M0, M1,...) Are generated by a modulation signal generation circuit (Un), and the modulation signals (M0, M1) are generated. ,...), The on and off states of the switches (Z0, Z1,...) Are controlled in correspondence with the true and false (or false and true) of the respective bits.
That is, the gain of the lamp current detection signal conversion circuit (Ai) is variable depending on the combination of true and false of each bit of the modulation signal (M0, M1,...).

Therefore, the lamp current detection signal conversion circuit (Ai) gives the lamp current correlation obtained by giving a gain determined by the state of the modulation signal (M0, M1,...) To the lamp current detection signal (Si) as an input. A signal (Sj) is output.
At this time, the amount of gain change caused by the change of each bit of the modulated signal (M0, M1,...) Between true and false, that is, the weight of each bit, is the bit of the modulated signal (M0, M1,...). Each of the gray scale gains can be set with a small number of modulation signals (M0, M1,...), That is, the number of bits, by appropriately selecting and configuring the weight of each bit. .
For example, when the modulation signal is 3 bits, the gain gradation is 8 gradations.
The lamp current detection signal conversion circuit (Ai) is normally configured as an amplifier, but may be an attenuator.

The power supply capacity control circuit (Ud) receives the lamp current correlation signal (Sj) and a lamp current target signal (St) that is a control target value of this signal, and the power supply capacity control circuit (Ud) Compare these two signals.
If the lamp current correlation signal (Sj) is smaller than the lamp current target signal (St), the lamp current correlation signal (Sj) is reversed so that the lamp current (IL) increases. When the lamp current target signal (St) is larger, the output of the gate drive signal (Sg) to the power supply circuit (Ux) is feedback-controlled so that the lamp current (IL) is decreased, whereby the lamp current (IL) is reduced. Control is performed so that the current correlation signal (Sj) matches the lamp current target signal (St).

On the other hand, the output voltage of the power feeding circuit (Ux), that is, the lamp voltage (VL) is detected by the lamp voltage detecting means (Vx), and a lamp voltage detection signal (Sv) is generated and input to the power control circuit (Up). .
The power control circuit (Up) uses the lamp voltage detection signal (Sv) so that the load power value PL applied to the discharge lamp (Ld) becomes a predetermined target power value PT. It has a function of updating the lamp current target signal (St).

  Since the discharge lamp lighting device of the present invention is configured in this way, the modulation signal generation circuit (Un) generates the desired combination of the modulation signals (M0, M1,...) The gain of the current detection signal conversion circuit (Ai) can be directly modulated. As a result, the power supply circuit (Ux) is immediately feedback-controlled by the function of the power supply capacity control circuit (Ud), and the lamp current Since (IL) is modulated, high-speed modulation of the brightness of the light source can be realized.

First, with respect to the prior art, in the HID lamp, since the lamp voltage changes, when trying to modulate the lamp power for dimming, for example, by specifying the lamp current, the power is reduced. Although it has been stated that it is necessary to change the “amount correlated with the power target value”, it is not possible to specify the lamp current in the discharge lamp lighting device of the present invention. Instead, it should be noted that the gain of the lamp current detection signal conversion circuit (Ai) is specified.
Here, by setting the gain of the lamp current detection signal conversion circuit (Ai) in this way, the power can be correctly set regardless of the current that flows as described above, approximately like a Zener diode. Furthermore, it utilizes the unique feature of HID lamps that the lamp voltage can be considered constant.

It is assumed that the gain of the lamp current detection signal conversion circuit (Ai) based on the modulation signals (M0, M1,...) Generated by the modulation signal generation circuit (Un) is a certain value. At this time, the power control circuit (Up) repeats, for example, periodically the operation of updating the lamp current target signal (St) so that the load power value PL matches the target power value PT.
Next, the modulation signal generation circuit (Un) changes the modulation signal (M0, M1,...) To set the gain of the lamp current detection signal conversion circuit (Ai) to, for example, 10% of the original value. Assuming that a large value is generated, the power supply capacity control circuit (Ud) detects that the lamp current correlation signal (Sj), which was originally substantially equal to the lamp current target signal (St), has increased, By performing feedback control of the power feeding circuit (Ux) so as to restore this state, the lamp current (IL) is consequently reduced to a value smaller by 10% than the original, but the lamp voltage is kept constant. It can be seen that the lamp power will be reduced to a value that is 10% smaller, and it can be seen that the correct power specified modulation is achieved.

As described above, during the modulation in the discharge lamp lighting device of the present invention, the target power value PT and the lamp current target signal (St) are not operated.
Further, in the discharge lamp lighting device of the present invention, even if the power control circuit (Up) includes a microprocessor, for example, each switch (Z0, Z1,...) Is turned on and off for modulation. The microprocessor is not involved in determining the state.
Therefore, the discharge lamp lighting device of the present invention requires complicated processing such as AD conversion, multiplication and division operations by the microprocessor of the AD converted data, and complex processing such as analog multiplication and division operations. Instead, the on-state and off-state of each switch (Z0, Z1,...) Are directly controlled by the modulation signal (M0, M1,...), And therefore the gain of the lamp current detection signal conversion circuit (Ai) is controlled. Is directly modulated at high speed, so that high-speed modulation is possible without causing jitter in the dimming profile.

In the discharge lamp lighting device of the present invention, it should be noted that the power control and dimming in the prior art are functionally separated from the brightness modulation of the light source as described above. Actually, also in the discharge lamp lighting device of the present invention, as described above, by updating the lamp current target signal (St) so that the load power value PL matches the target power value PT, a predetermined power is obtained. It is also possible to perform dimming similar to that of the prior art by changing the target power value PT by receiving a dimming signal from the outside, for example.
However, in the case of the present invention, independent of such power control and dimming, a path for the modulation signal is provided separately, and high-speed modulation operation is performed without using a power control mechanism as in the prior art. This is a technical feature of the present invention.

  As described above, by setting the gain of the lamp current detection signal conversion circuit (Ai), the power can be set correctly. Therefore, when the lamp voltage (VL) changes, a power error may occur. Therefore, for the predetermined period from the start of lighting as described above, for example, the period from the start of lighting until the lamp voltage (VL) is stabilized, a predetermined combination as the modulation signal (M0, M1,...) For example, it is desirable to prevent the modulation operation by generating a signal of a combination that minimizes the gain of the lamp current detection signal conversion circuit (Ai).

  Note that the period from the start of lighting until the lamp voltage (VL) is stabilized is simply determined as a predetermined period, for example, when the lamp is started when the lamp is at room temperature. Although it may be the longest value of the variation for the period required until the required stability of the voltage is obtained, for example, based on the time change of the lamp voltage detection signal (Sv), the rate of change is a predetermined constant value, for example. The period until it is detected that the following has been reached is even better because when the lamp is turned on when the lamp is in a high temperature state, the blocking of the modulation operation can be canceled quickly.

Note that when the discharge lamp lighting device of the present invention is applied to, for example, the projector described in the background art section, the modulation signal generation circuit (Un) performs image processing as the dimming request generation circuit (Uy). The modulation signal (M0, M1,...) Is generated by receiving a signal including dimming information from the circuit.
When the discharge lamp lighting device of the present invention is applied to, for example, the photoacoustic analyzer described in the background art section, the modulation signal generation circuit (Un) is used as the dimming request generation circuit (Uy). And receiving the signal including the dimming information from the optical waveform generation circuit, the modulation signals (M0, M1,...) Are generated.
Thus, based on FIG. 1, the content of invention of Claim 1 was demonstrated.

Next, the form for implementing this invention is demonstrated using FIG. 2 which is a block diagram which simplifies and shows the 2nd Example of the discharge lamp lighting device of this invention. In FIG. 2, portions having the same configuration as the embodiment of FIG. 1 are omitted.
In this case, the modulation signal generation circuit (Un) receives the original modulation signals (F0, F1,...) From the external original dimming signal generation circuit (Um), and the modulation signals (M0, M1,. ...) is generated.

The data change circuit (Us) in the modulation signal generation circuit (Un) passes the original modulation signals (F0, F1,...) As they are when the modulation permission signal (Ss) is active. Are output as signals (M0, M1,...), And conversely, when the modulation permission signal (Ss) is inactive, the original modulation signals (F0, F1,. Is a circuit having a function of outputting as the modulation signals (M0, M1,...).
When the original modulated signals (F0, F1,...) Are passed as they are, naturally, for example, conversion of a signal carrier such as converting a current signal into a voltage signal or converting an optical signal into an electric signal. Or demodulating a signal, such as demodulating a frequency-modulated signal, for example, changing the signal amplitude or converting a two-wire differential signal into a single-wire signal, eg, a high-active signal is low-active Conversion of signal logic such as conversion to the above signal can be appropriately performed as necessary.

  The modulation permission signal (Ss) is generated by the power control circuit (Up), and the power control circuit (Up) is configured to output the modulation permission signal (Up) during a period from the start of lighting until the lamp voltage (VL) is stabilized. Ss) is deactivated.

  In the above, it has been described that it is desirable to prevent the modulation operation during the period from the start of lighting until the lamp voltage (VL) is stabilized, but by configuring the discharge lamp lighting device in this way, from the start of lighting. During the period until the ramp voltage (VL) is stabilized, the modulation permission signal (Ss) is in an inactive state, and in this state, the modulation signal generation circuit (Un) causes the modulation signals (M0, M1) to be inactive. ,...) Can be generated and the modulation operation can be prevented, so that the original modulation signal (F0, F1,...) Does not sense the stability of the ramp voltage (VL). Even when it is generated by the circuit, it is possible to prevent the occurrence of the power error due to the change in the lamp voltage (VL).

  As described above, in the power supply capacity control circuit (Ud), feedback control is performed so that the lamp current correlation signal (Sj) and the lamp current target signal (St) match, and the power control circuit (Up) ) To update the lamp current target signal (St) so that the load power value PL input to the discharge lamp (Ld) becomes a predetermined target power value PT, a double feedback structure is used. Have.

In the foregoing, it has been described that the lamp voltage can be regarded as being constant irrespective of the current flowing like a Zener diode. Strictly speaking, when the lamp current (IL) changes, the lamp voltage (VL) also changes. Since it changes slightly, if the lamp current (IL) is changed by the modulation operation based on the modulation signal (M0, M1,...), The operation for updating the lamp current target signal (St) is disturbed. However, in the control of the double feedback structure, for example, the operation may become unstable in relation to the relation between the period of the disturbance and the period of updating the lamp current target signal (St).
As a countermeasure for avoiding this problem, it is desirable to stop the operation of updating the lamp current target signal (St) in the discharge lamp lighting device based on the contents of the original modulation signals (F0, F1,...). In the period determined by the original dimming signal generation circuit (Um), it is preferable that the discharge lamp lighting device can be controlled as such by the original dimming signal generation circuit (Um).

In order to realize this, as indicated by a broken line in FIG. 2, a current target update permission signal (Sf) can be input from the original dimming signal generation circuit (Um) to the power control circuit (Up). When the current target update permission signal (Sf) is in an inactive state, the power control circuit (Up) stops the operation of updating the lamp current target signal (St).
However, even during or after the lamp voltage (VL) is stabilized after the start of lighting, the lamp voltage (VL) is caused by, for example, a change in lamp cooling conditions. ), The power control circuit (Up) ignores the current target update permission signal (Sf) even if it is inactive and ignores the lamp current. The operation for updating the target signal (St) should be performed.

  The discharge lamp lighting device of the present invention for updating the lamp current target signal (St) so that the load power value PL input to the discharge lamp (Ld) becomes a predetermined target power value PT. As the configuration of the power control circuit (Up), for example, a configuration in which the lamp current target signal (St) is calculated based on a value obtained by dividing the target power value PT by the lamp voltage (VL), or the lamp voltage There is a configuration in which the product of (VL) and the lamp current (IL) and the target power value PT are compared and the lamp current target signal (St) is increased or decreased so as to reduce the difference. When the lamp current (IL) is changed by the modulation operation based on the modulation signal (M0, M1,...) As in the case of the configuration of (5), the power control circuit (Up) In the case of a configuration that operates so as to cancel out, the configuration that prevents the lamp current target signal (St) from being updated when the current target update permission signal (Sf) described above is in an inactive state is adopted. Should.

In this case, when the current target update permission signal (Sf) is activated, the combination of the original modulation signals (F0, F1,...) Input during that period is the current target update permission every time. Each time the signal (Sf) is activated, it should be the same or close to the modulation amount (combination of the original modulation signals (F0, F1,...) With close power).
If the modulation amount differs greatly every time the current target update permission signal (Sf) becomes active, the power control circuit (Up) sets the value of the lamp current target signal (St). This is because a large change must be made, and the instability of the operation may increase.

Even after the period from the start of lighting until the lamp voltage (VL) stabilizes, the lamp voltage (VL) may change gradually. The lamp voltage (VL) may change greatly due to changes in cooling conditions.
When a change in the direction of increasing the lamp voltage (VL) occurs, if the inactive state of the current target update permission signal (Sf) continues for a long time, the rated power of the discharge lamp (Ld) More power may be applied, and the lamp may overheat, resulting in a dangerous condition such as life deterioration or damage.
Therefore, it is desirable to update the lamp current target signal (St) at an appropriate frequency, and the current target update permission signal (Sf) should be generated to be activated at an appropriate frequency.

  Therefore, when the power control circuit (Up) monitors the duration of the inactive state of the current target update permission signal (Sf) and detects that the duration is a predetermined time or more, The lamp current target signal (St) is set so that the modulation permission signal (Ss) is deactivated and the load power value PL applied to the discharge lamp (Ld) becomes a predetermined target power value PT. Since the modulation operation can be stopped by updating the signal, even if the activation of the current target update permission signal (Sf) is interrupted or the frequency decreases, the operation can be continued in a safe state. it can.

When the activation of the current target update permission signal (Sf) is resumed later even when the modulation operation is stopped by the function described here because the activation of the current target update permission signal (Sf) is interrupted. Should be able to release the modulation stop and resume the modulation operation.
Thus, based on FIG. 2, the content of the invention of Claims 1-4 was demonstrated.

Next, each invention will be further described below with reference to drawings showing more specific configurations.
FIG. 3 shows a simplified example of the configuration of the discharge lamp lighting device (Ex) of the present invention by the DC driving method.

In the discharge lamp lighting device (Ex) of the present invention, a power supply circuit (Ux) based on a step-down chopper circuit operates by receiving a voltage supplied from a DC power source (Mx) such as a PFC, and supplies the discharge lamp (Ld). Adjust the power supply amount. In the power supply circuit (Ux), a current from a DC power source (Mx) is turned on / off by a switching element (Qx) such as an FET, and a smoothing capacitor (Cx) is charged through a choke coil (Lx). This voltage is applied to the discharge lamp (Ld) so that a current can flow through the discharge lamp (Ld).
During the period when the switch element (Qx) is in the ON state, the current through the switch element (Qx) directly charges the smoothing capacitor (Cx) and supplies the current to the discharge lamp (Ld) as a load. In addition, energy is stored in the form of magnetic flux in the choke coil (Lx), and the flywheel diode is generated by the energy stored in the form of magnetic flux in the choke coil (Lx) while the switch element (Qx) is in the OFF state. Charging to the smoothing capacitor (Cx) and current supply to the discharge lamp (Ld) are performed via (Dx).

In the step-down chopper-type power supply circuit (Ux), power is supplied to the discharge lamp according to a ratio of a period during which the switch element (Qx) is in an on state, that is, a duty cycle ratio, to an operation cycle of the switch element (Qx). The amount can be adjusted.
Here, a gate drive signal (Sg) having a certain duty cycle ratio is generated by the power supply control circuit (Fx), and the gate terminal of the switch element (Qx) is controlled via the gate drive circuit (Gx). The on / off of the current from the DC power source (Mx) is controlled.

In the starter (Ui), the capacitor (Ci) is charged by the ramp voltage (VL) through the resistor (Ri). When the gate drive circuit (Gi) is activated, the switch element (Qi) made of a thyristor or the like conducts, whereby the capacitor (Ci) is discharged through the primary winding (Pi) of the transformer (Ki). A high voltage pulse is generated in the secondary winding (Hi). The high voltage generated in the secondary winding (Hi) of the starter (Ui) is superimposed on the output voltage of the power feeding circuit (Ux) and applied between the electrodes (E1, E2) to discharge the discharge lamp (Ld). Can be started.
The starting method in this figure is different from the starting method in FIG. 1, but the triggering method for starting is irrelevant to the essence of the present invention.

The lamp current (IL) flowing between the electrodes (E1, E2) of the discharge lamp (Ld) and the lamp voltage (VL) generated between the electrodes (E1, E2) are the lamp current detection means (Ix), The lamp voltage detecting means (Vx) is configured so that it can be detected.
The lamp current detecting means (Ix) can be easily realized by using a shunt resistor, and the lamp voltage detecting means (Vx) can be easily realized by using a voltage dividing resistor.
The lamp current detection signal (Si) from the lamp current detection means (Ix) and the lamp voltage detection signal (Sv) from the lamp voltage detection means (Vx) are input to the power supply control circuit (Fx).

FIG. 4 shows a simplified configuration of the power supply control circuit (Fx) shown in FIG.
The lamp voltage detection signal (Sv) is input to an AD converter (Adc) in the power control circuit (Up), converted into digital lamp voltage data (Sxv) having an appropriate number of digits, and the microprocessor. Input to the unit (Mpu).
Here, the microprocessor unit (Mpu) includes a CPU, a program memory, a data memory, a clock pulse generation circuit, a time counter, an IO controller for inputting / outputting digital signals, and the like.

The microprocessor unit (Mpu) has a chopper capability for a power supply capability control circuit (Ud) to be described later based on a calculation referring to the lamp voltage data (Sxv) and a condition determination according to the state of the system at that time. Control target data (Sxt) is generated. The chopper capacity control target data (Sxt) is converted into an analog lamp current target signal (St) by the DA converter (Dac) and input to the power supply capacity control circuit (Ud).
Further, a lamp current upper limit signal (Sk) for defining an upper limit value ILmax of the allowable lamp current (IL) is generated by the lamp current upper limit signal generation circuit (Uc) and input to the power supply capacity control circuit (Ud). Is done.

In the power supply capacity control circuit (Ud), the lamp current target signal (St) is further passed through an amplifier or buffer (Ad1) and a diode (Dd1) provided as necessary, and further, the lamp current upper limit signal ( Sk) is connected to one end of the pull-up resistor (Rd1) through an amplifier or buffer (Ad2) and a diode (Dd2) provided as necessary, and a chopper drive target signal (Sd2) is generated.
The other end of the pull-up resistor (Rd1) is connected to a reference voltage source (Vd1) having an appropriate voltage.
Therefore, the chopper drive target signal (Sd2) is larger of the signal (Sd3) corresponding to the lamp current target signal (St) or the signal (Sd4) corresponding to the lamp current upper limit signal (Sk). The signal that does not exist is the selected signal.

  That is, the power control circuit (Up), for example, calculates a value of the lamp current (IL) for achieving the rated power by dividing a constant corresponding to the rated power by the lamp voltage data (Sxv), Even if the lamp current target signal (St) is generated by some method such as generating it corresponding to this value, even if this is inappropriate, the hardware in the power supply capacity control circuit (Ud) Therefore, the chopper drive target signal (Sd2) is limited so that the lamp current (IL) does not exceed the lamp current upper limit signal (Sk).

  Incidentally, the control via the AD converter (Adc) and the microprocessor unit (Mpu) described above has a slow operation speed (or a high cost if it is fast), so that the discharge state of the lamp suddenly changes, for example. When a situation occurs, the above-described lamp current target signal (St) may be inappropriate due to the operation delay. Therefore, configuring such a current limiting function in hardware means that the lamp or power supply This is also beneficial from the viewpoint of protecting the device.

  On the other hand, the lamp current detection signal (Si) is converted by the lamp current detection signal conversion circuit (Ai) based on the modulation signal (M0, M1,...), And an amplifier or buffer (Ad3) and a diode provided as necessary. Via (Dd3), one end is connected to the other end of the pull-down resistor (Rd5) connected to the ground (Gndx), and the control target signal (Sd5) is generated.

Further, the lamp voltage detection signal (Sv) is compared with a voltage of a reference voltage source (Vd2) having a voltage corresponding to the above-described no-load open voltage by a comparator (Cmv). When (Sv) is higher than the no-load open-circuit voltage, the transistor (Qd1) is turned off or activated, and the pull-down is performed from an appropriate voltage source (Vd3) through a resistor (Rd4) and a diode (Dd4). By causing a current to flow through the resistor (Rd5), the level of the control target signal (Sd5) is increased.
Conversely, when the lamp voltage detection signal (Sv) is lower than the no-load open voltage, the transistor (Qd1) is turned on, so that the current from the voltage source (Vd3) is short-circuited, and the control target The signal (Sd5) corresponds to the lamp current detection signal (Si).
In any case, the circuit composed of the pull-down resistor (Rd5), the diode (Dd3), and the diode (Dd4) corresponds to the smaller one of the signal (Sd6) and the signal (Sd7) on the anode side of each diode. This is because the voltage is selected and generated in the pull-down resistor (Rd5).
With this configuration, even if the output current is almost stopped and the lamp current detection signal (Si) is hardly input, the lamp voltage detection signal (Sv) is the unloaded open voltage. As the control target signal (Sd5) rises rapidly, the lamp voltage (VL) is always limited in terms of hardware below the approximate no-load open voltage.

The chopper drive target signal (Sd2) is divided by a resistor (Rd2) and a resistor (Rd3) and input to the inverting input terminal of the operational amplifier (Ade).
On the other hand, the control target signal (Sd5) is input to the non-inverting input terminal of the operational amplifier (Ade).
Since the output signal (Sd1) of the operational amplifier (Ade) is fed back to the inverting input terminal via the integrating capacitor (Cd1) and the speed-up resistor (Rd6), the operational amplifier (Ade) It functions as an error integration circuit that integrates the difference between the voltage of the control target signal (Sd5) and the divided voltage of the resistance (Rd2) and the resistance (Rd3) of the chopper drive target signal (Sd2).

An oscillator (Osc) to which a resistor (Rd0) and a capacitor (Cd0) for determining a time constant are connected generates a sawtooth wave signal (Sd0) as shown in FIG. Sd0) and the output signal (Sd1) of the error integration circuit are compared by a comparator (Cmg).
However, in the comparison, a signal (Sd8) obtained by adding an offset voltage (Vd4) to the output signal (Sd1) of the error integration circuit is compared with the sawtooth wave signal (Sd0).
The gate drive signal (Sg) that is at a high level during a period in which the voltage of the sawtooth wave signal (Sd0) is higher than the voltage of the signal (Sd8) is generated and output from the power supply capability control circuit (Ud). .
As described above, since the signal (Sd8) is obtained by adding an offset to the output signal (Sd1) of the error integration circuit, even if the output signal (Sd1) of the error integration circuit is zero, The duty cycle ratio of the gate drive signal (Sg) is configured to be a certain maximum value smaller than 100%, that is, the maximum duty cycle ratio DXmax or less.
5a and 5b show the output signal (Sd1) of the error integration circuit, a signal (Sd8) obtained by adding an offset thereto, the sawtooth wave signal (Sd0) and the gate drive signal (Sg). The relationship is shown.

The gate drive signal (Sg) output from the power supply control circuit (Fx) is input to the gate drive circuit (Gx), resulting in the lamp current detection signal (Si) and the lamp voltage detection. A feedback control system in which the signal (Sv) is fed back to the operation of the switch element (Qx) is completed.
3 is configured as a commercially available integrated circuit in which the operational amplifier (Ade), the oscillator (Osc), the comparator (Cmg), and the like are integrated. TL494 manufactured by company or the like can be used.

FIG. 6 shows a simplified configuration of the lamp current detection signal conversion circuit (Ai) shown in FIG.
The lamp current detection signal conversion circuit of this figure is based on a non-inverting amplifier circuit using an operational amplifier (Aai), and the lamp current detection signal (Si) is amplified by the operational amplifier (Aai), and the output signal is a ramp. A current correlation signal (Sj) is generated.

The output of the operational amplifier (Aai) is divided by a resistor (Rfc) and a combined resistance of the resistor (Rac) and a resistor connected in parallel to the resistor (Rac) and connected to the ground, and is divided into the operational amplifier (Aai). ), The gain of the non-inverting amplifier circuit is defined by the voltage dividing ratio.
Since switches (Z0, Z1, Z2) by transistors are inserted between the resistors (Ra0, Ra1, Ra2) connected in parallel to the resistor (Rac) and the ground, the switches (Z0, Z1, Z2) Since each resistor (Ra0, Ra1, Ra2) can be switched between a connected state and a non-connected state by turning on or off, the gain of the non-inverting amplifier circuit can be varied.
The switches (Z0, Z1, Z2) are connected to the modulation signals (M0, M1, M2) through the base resistors (Rm0, Rm1, Rm2), respectively. Z2) is controlled in an on state and an off state corresponding to the true and false of each bit of the modulated signal (M0, M1, M2), and as a result, each of the modulated signals (M0, M1, M2). The gain of this non-inverting amplifier circuit can be varied by a combination of true and false bits.

Here, as the relationship of the resistance values of the resistors (Ra0, Ra1, Ra2), modulation is performed by setting the resistor (Ra0) to twice the resistor (Ra1) and the resistor (Ra1) to twice the resistor (Ra2). The gain of the non-inverting amplifier circuit can be varied as 3-bit binary data with the signal (M0) as the least significant bit and the modulation signal (M2) as the most significant bit.
However, the gain of the non-inverting amplifier circuit and the binary data are not in a linear relationship.
In addition, although the case of 3 bits was shown here as an example, it can be similarly configured by increasing or decreasing the number of bits as necessary.

FIG. 7 shows a simplified configuration of the modulation signal generation circuit (Un) shown in FIG.
In this figure, the lamp current detection signal conversion circuit (Ai) of FIG. 6 is also omitted.

An original current target update permission signal (Sfi) is input from the terminal (Ts), and a signal is transmitted to the phototransistor (Qfi) constituting the photocoupler via the resistor (Rf1) and the LED (Dfi). The collector is connected to a circuit power supply (Vcc) having an appropriate voltage via a pull-up resistor (Rf2), whereby a current target update permission signal (Sf) is generated and input to the power control circuit (Up). Is done.
Here, the current target update permission signal (Sf) is defined as an active state when it is at a low level.
The modulation signal generation circuit (Un) also serves as an interface with the original dimming signal generation circuit (Um) and, as will be described later, the current target update permission signal (Dfs1) via the diode (Dfs1). The current target update permission signal (Sf) is generated in the modulation signal generation circuit (Un) in order to devise to interfere with the second modulation permission signal (Ss ′) by Sf).

Similarly, the original modulation signals (F0, F1, F2) are input from the terminals (Tm0, Tm1, Tm2), and are respectively connected via the resistors (Rm10, Rm11, Rm12) and the LEDs (Dm0, Dm1, Dm2). A signal is transmitted to the phototransistors (Qm0, Qm1, Qm2) constituting the photocoupler.
Each collector is connected to a circuit power supply (Vcc) having an appropriate voltage through a pull-up resistor (Rm20, Rm21, Rm22), and the modulation signal (M0, Rm31, Rm32) is connected through a resistor (Rm30, Rm31, Rm32). M1, M2) are sent to the modulation signal generation circuit (Un).
Note that the anodes of the photocoupler LEDs (Dfi, Dm0, Dm1, and Dm2) are commonly connected to the terminal (Tc), and a power source for causing each LED to emit light is connected.

The power control circuit (Up) outputs a modulation permission signal (Ss). Here, the power control circuit (Up) is defined as an active state when it is at a high level.
When the modulation enable signal (Ss) is at a low level, the second modulation enable signal (Ss) appearing at the other end of the pull-up resistor (Rs1) connected to the circuit power supply (Vcc) via the diode (Dfs2). ') To low level.
When the second modulation permission signal (Ss ′) becomes low level, the transistor (QsH) can flow current from the collector through the base resistance (Rs2), and the base resistance (Rs4) is reduced. Thus, the transistor (QsL) can suck current from the collector.
On the contrary, when the second modulation permission signal (Ss ′) becomes a high level, the transistor (QsH) cannot flow current from the collector, and the transistor (QsL) can sink current from the collector. It becomes impossible.

The diode (Ds0, Ds1) has its anode connected to the modulation signal (M0, M1) and its cathode connected to the collector of the transistor (QsL). The diode (Ds2) has its cathode connected to the modulation signal (M2). ) Shows an example in which the anode is connected to the collector of the transistor (QsH).
In this case, when the modulation permission signal (Ss) becomes inactive, that is, at a low level, the modulation signal is transmitted via the diodes (Ds0, Ds1) regardless of the state of the original modulation signals (F0, F1, F2). (M0, M1) is set to a low level, and the modulation signal (M2) is set to a high level via a diode (Ds2).

Therefore, the portion composed of the diodes (Ds0, Ds1, Ds2) and the transistors (QsH, QsL) serves as the data changing circuit (Us), that is, the modulation permission signal (Ss) is not In the active state, a configuration for generating a predetermined combination of signals as the modulation signals (M0, M1,...) Is realized.
As described above, the power control circuit (Up) sets the modulation permission signal (Ss) in an inactive state during the period from the start of lighting until the lamp voltage (VL) is stabilized. Modulation operation can be prevented.

  In this case, the predetermined combination of signals is a combination of the low, low and high modulation signals (M0, M1, and M2). As can be easily understood from the above description, each diode (Ds0, Ds1, Ds2) is expressed when the modulation permission signal (Ss) is in an inactive state by changing the connection destination of the transistor (QsH) or the transistor (QsL). A predetermined combination of signals can be arbitrarily set.

In addition, when the current target update permission signal (Sf) is activated first, the combination of the original modulation signals (F0, F1,...) Input during the period is set to the current target update permission every time. It has been explained that every time the signal (Sf) is activated, it should be the same or close to the modulation amount (combination of the original modulation signals (F0, F1,...) With close power), but the diode (Dfs1 ) Are connected as shown in the figure, when the current target update permission signal (Sf) is in an active state, that is, at a low level, the second modulation permission signal (Ss ′) is passed through the diode (Dfs1). Since the signal becomes low level, the modulation signals (M0, M1, M2) that are the same as a predetermined combination of signals that are generated when the modulation permission signal (Ss) is inactive are automatically set. become, Convenient.
If this function is not necessary, the diode (Dfs1) can be simply removed.

In addition, about the said original current target update permission signal (Sfi) and the said original modulation signal (F0, F1, F2), the case where the signal was input using the photocoupler was described. In such an image display projector, these signals are generated by an image processing circuit. In general, such a circuit is a safety low-voltage circuit that does not require strong insulation from the part directly touched by the operator. It belongs to and is often sensitive to noise because of its high speed and precision, while the power feeding circuit (Ux) is a power system circuit and is a dangerous circuit because it is not insulated from a commercial power source. Further, since the circuit has a lot of noise such as switching noise and surge, it is often desirable to electrically isolate and insulate them.
Therefore, when such insulation is unnecessary, it is not necessary to use a photocoupler.

FIG. 6 shows an example of the lamp current detection signal conversion circuit (Ai) based on a non-inverting amplifier circuit using an operational amplifier. FIG. 8 also shows a non-inverting amplifier circuit based on an operational amplifier. An example of a part including a lamp current detection signal conversion circuit Ai ′ and a modulation signal generation circuit Un ′ is shown.
Resistors (Rac, Ra0, Ra1, Ra2) connected in parallel in FIG. 6 are serially connected resistors (Ra0 ′, Ra1 ′, Ra2 ′, Rac ′) in FIG. Since each of (Ra0 ′, Ra1 ′, Ra2 ′) can be switched between a short circuit state and a non-short circuit state by turning on or off each of the switches (Z0 ′, Z1 ′, Z2 ′) by the transistors constituting the photocoupler, The gain of the inverting amplifier circuit can be varied.

Current path from a terminal (Tc) to which power is supplied to illuminate the LEDs (Dfi, Dm0, Dm1, Dm2) of the photocouplers that control the on / off of the switches (Z0 ′, Z1 ′, Z2 ′). Is switched off using the photocoupler transistor (Qs ′), so that all the switches (Z0 ′, Z1 ′, Z2 ′) are turned off regardless of the state of the original modulation signals (F0, F1, F2). The gain of the non-inverting amplifier circuit can be minimized.
A modulation permission signal (up) from the power control circuit (Up), which is defined as an active state when the photocoupler LED (Ds ′) for controlling on / off of the photocoupler transistor (Qs ′) is at a low level. Ss) is driven through a resistor (Rs ′) connected to a circuit power supply (Vcc). When the modulation permission signal (Ss) is in an inactive state, the modulation signal (Ss) A configuration for generating a predetermined combination of signals as M0, M1,.
In this case, the modulation signals (M0, M1, M2) correspond to optical signals (or currents of the respective LEDs) that are the outputs of the LEDs (Dm0, Dm1, Dm2).

Similarly, FIG. 9 shows an example of a portion including a lamp current detection signal conversion circuit Ai ″ and a modulation signal generation circuit Un ″, which are also based on a non-inverting amplifier circuit using an operational amplifier.
In FIG. 8, the gain of the non-inverting amplifier circuit is made variable by changing the combined resistance on the side connected to the ground. However, in FIG. 9, the resistance (Rac ”on the side connected to the ground is changed. ) Is unchanged, the resistances on the feedback side are resistances (Ra0 ″, Ra1 ″, Ra2 ″, Rfc ″), and the resistors (Ra0 ″, Ra1 ″, Ra2 ″) are switched by transistors that constitute photocouplers ( Z0 ″, Z1 ″, Z2 ″) can be switched between a short-circuited state and a non-short-circuited state by turning each on or off, so that the gain of the non-inverting amplifier circuit can be varied.

When the transistor (Qs ″) is in an on state, a current for making the LEDs (Dfi, Dm0, Dm1, Dm2) of the photocouplers that control the on / off of the switches (Z0 ′, Z1 ′, Z2 ′) light on In addition, by being able to be supplied via diodes (Dn0, Dn1, Dn2) and resistors (Rn0, Rn1, Rn2), regardless of the state of the original modulation signals (F0, F1, F2), All of the switches (Z0 ′, Z1 ′, Z2 ′) can be turned on to minimize the gain of the non-inverting amplifier circuit.
The LED (Ds ″) of the photocoupler that controls on / off of the transistor (Qs ″) is controlled by a modulation permission signal (Ss) from the power control circuit (Up) that is defined as an active state when the level is high. If it is driven through a resistor (Rs ″) connected to a circuit power supply (Vcc), when the modulation permission signal (Ss) is in an inactive state, the modulation signals (M0, M1) ,...) To generate a signal having a predetermined combination.
The emitter of the transistor (Qs ″) is connected to a terminal (Tg) to which a ground of a power supply (Vm) for making the LEDs (Dfi, Dm0, Dm1, Dm2) shine is connected.
Also in this case, the modulation signals (M0, M1, M2) correspond to optical signals (or currents of the respective LEDs) that are the outputs of the LEDs (Dm0, Dm1, Dm2).

As described above, in the discharge lamp lighting device according to the present invention, the lamp current detection signal conversion circuit (Ai) can have various configurations, other than the non-inverting amplifier shown here. In addition, one based on an inverting amplifier or one not using an amplifier can be used.
In the description so far, a plurality of switches (Z0, Z1,...) Whose on state and off state are controlled corresponding to the true and false of each bit of the modulation signal (M0, M1,. It is assumed that one switching element is provided for each of the modulation signals (M0, M1, M2), that is, corresponding to true and false of the modulation signal (M0). A switch (Z0) whose state and off state are controlled, a switch (Z1) whose on state and off state are controlled corresponding to the true and false of the modulation signal (M1), and the true and false of the modulation signal (M2) Although an example including a switch (Z2) whose ON state and OFF state are controlled in response to false is illustrated, a plurality of switch elements correspond to each of the modulation signals (M0, M1,...). Even those provided There.
For example, as shown in FIG. 10, two switch elements are provided corresponding to each of the modulation signals (M0, M1, M2), that is, true and false of the modulation signal (M0). Switch elements (Z0a, Z0b) whose on-state and off-state are controlled in correspondence with each other, and switch elements (Z1a, Z1b) whose on-state and off-state are controlled in correspondence with the true and false of the modulation signal (M1) ), And switch elements (Z2a, Z2b) whose on-state and off-state are controlled corresponding to the true and false of the modulation signal (M2).
In the case of the lamp current detection signal conversion circuit (Ai0) shown in FIG. 10, the switch elements (ON and OFF states are controlled corresponding to the true and false of each bit of the modulation signal (M0, M1, M2)). Since the inverters (I0, I1, I2) are inserted in the bases of the switch elements (Z0b, Z1b, Z2b) with respect to Z0a, Z1a, Z2a), the switch elements (Z0a) and the switch elements (Z0b) If one is on, the other is off; the switch element (Z1a) and the switch element (Z1b) are off if one is on; the switch element (Z2a) and the switch element (Z2b) If one is on, the other is off.
Further, as shown in FIG. 10, for example, a ladder resistor network (RA0) may be used or a DA conversion IC may be used.

  Although FIG. 3 shows a power supply circuit (Ux) based on a step-down chopper type DC-DC converter, other types of converters such as a step-up chopper type and an inverting (or step-up / down) chopper type, a transformer It can be configured by an arbitrary power supply circuit such as one using a resonance circuit.

  In the present specification, the description has been made mainly on the DC drive type discharge lamp lighting device. However, since the feature of the present invention is irrelevant to the type of the lamp, for example, a full bridge inverter is provided in the subsequent stage of the converter. The present invention is also applicable to an AC drive type discharge lamp lighting device such as the above.

The circuit configuration described in this specification describes the minimum necessary components in order to explain the operation, function, and operation of the light source device of the present invention.
Therefore, the details of the circuit configuration and operation described, such as signal polarity, selection, addition, omission of specific circuit elements, or ingenuity such as changes based on the convenience of obtaining elements and economic reasons Is assumed to be performed at the time of designing the actual device.

In particular, a mechanism for protecting circuit elements such as switching elements such as FETs of the power supply device from damage factors such as overvoltage, overcurrent, and overheating, or radiation noise and conduction noise generated by the operation of circuit elements of the power supply device Mechanisms that reduce the occurrence of noise and prevent the generated noise from being output to the outside, such as snubber circuits, varistors, clamp diodes, current limiting circuits (including pulse-by-pulse systems), common mode or normal mode noise filter chokes It is assumed that a coil, a noise filter capacitor, and the like are added to each part of the circuit configuration described in the embodiment as necessary.
The configuration of the discharge lamp lighting device according to the present invention is not limited to the circuit system described in the present specification, and is not limited to the waveform and timing diagram described.

  Further, for example, the power control circuit (Up) of the power supply control circuit (Fx) in FIG. 1 performs AD conversion on the lamp voltage detection signal (Sv) corresponding to the lamp voltage (VL), based on this The lamp current target signal (St) is set, but the lamp current detection signal (Si) corresponding to the lamp current (IL) is also AD-converted, and the obtained current value becomes the target current value. By correcting and setting the lamp current target signal (St) so as to coincide with each other, high precision and high functionality for correcting the influence of variation of each circuit element parameter, or conversely, for example, the micro current The effects of the present invention can be satisfactorily achieved even when the configuration of the light source device is diversified, such as simplification by eliminating the processor unit (Mpu) and replacing it with a simpler control circuit.

  In this specification, the projector and the photoacoustic analyzer are described with respect to the application of the present invention. However, the discharge lamp lighting device of the present invention can be effectively used for any application for modulating the brightness of the discharge lamp. .

The block diagram which simplifies and shows the discharge lamp lighting device of this invention is represented. The block diagram which simplifies and shows a part of discharge lamp lighting device of this invention is represented. 1 illustrates an example of a simplified configuration of a DC drive type discharge lamp lighting device of the present invention. An example of the simplified structure of the electric power feeding control circuit of the discharge lamp lighting device of this invention is represented. The operation | movement of the electric power feeding control circuit of the discharge lamp lighting device of this invention is represented. 2 shows a simplified configuration of a lamp current detection signal conversion circuit of a discharge lamp lighting device according to the present invention. 2 shows a simplified configuration of a modulation signal generation circuit of a discharge lamp lighting device according to the present invention. An example of the part which consists of a modulation signal generation circuit and a modulation signal generation circuit of the discharge lamp lighting device of the present invention is shown. An example of the part which consists of a modulation signal generation circuit and a modulation signal generation circuit of the discharge lamp lighting device of the present invention is shown. 2 shows a simplified configuration of a lamp current detection signal conversion circuit of a discharge lamp lighting device according to the present invention.

Explanation of symbols

A00 operational amplifier Aai operational amplifier Ad1 buffer Ad2 buffer Ad3 buffer Adc AD converter Ade operational amplifier Ai lamp current detection signal conversion circuit Ai 'lamp current detection signal conversion circuit Ai "lamp current detection signal conversion circuit Ai0 lamp current detection signal conversion circuit Cd0 Capacitor Cd1 Integration capacitor Ci Capacitor Cmg Comparator Cmv Comparator Cx Smoothing capacitor Dac DA converter Dd1 Diode Dd2 Diode Dd3 Diode Dd4 Diode Dfi LED
Dfs1 Diode Dfs2 Diode Dm0 LED
Dm1 LED
Dm2 LED
Dn0 Diode Dn1 Diode Dn2 Diode Ds' LED
Ds ”LED
Ds0 Diode Ds1 Diode Ds2 Diode Dx Flywheel diode E1 Electrode E2 Electrode Trigger electrode Ex Discharge lamp lighting device F0 Original modulation signal F1 Original modulation signal F2 Original modulation signal Fx Feed control circuit Gi Gate drive circuit Gndx Ground Gx Gate drive circuit Hi 2 Secondary winding I0 Inverter I1 Inverter I2 Inverter IL Lamp current Ix Lamp current detection means Ki Transformer Ld Discharge lamp Lx Choke coil M0 Modulation signal M1 Modulation signal M2 Modulation signal Mpu Microprocessor unit Mx DC power supply Osc Oscillator Pi Primary winding Qd1 transistor Qfi phototransistor Qi switch element Qm0 phototransistor Qm1 phototransistor Qm2 phototransistor Qs' transistor Qs "transistor Star QsH Transistor QsL Transistor Qx Switch element R00 Resistor R01 Resistor R02 Resistor R03 Resistor R04 Resistor R05 Resistor R06 Resistor R10 Resistor R11 Resistor R12 Resistor R13 Resistor R14 Resistor R15 Resistor RA0 Ladder resistor network Ra0 Resistor Ra0 'Resistor Ra1 Resistor Ra1 Resistor Ra1 Resistor Resistor Ra1 "Resistor Ra2 Resistor Ra2 'Resistor Ra2" Resistor Rac Resistor Rac' Resistor Rac "Resistor Rb0 Resistor Rb1 Resistor Rb2 Resistor Rd0 Resistor Rd1 Pull-up Resistor Rd2 Resistor Rd3 Resistor Rd4 Resistor Rd5 Pull-down Resistor Rd1 Speed-up Resistor Rf1 Resistor Rfc Resistor Rfc ”Resistor Ri Resistor Rm0 Base resistor Rm1 Base resistor Rm10 Resistor Rm11 Resistor Rm12 Resistor Rm2 Base resistor Rm20 Pull-up resistor Rm21 Pull-up resistor Rm22 Pull-up resistor Rm30 Resistor Rm31 Resistor Rm32 Resistor Rn0 Resistor Rn1 Resistor Rn2 Resistor Rs' Resistor Rs "Resistor Rs1 Pull-up resistor Rs2 Base resistor Rs3 Resistor Rs4 Base resistor Rs5 Resistor Sd0 Output signal Sd1 Sd2 Chopper drive target signal Sd3 Signal Sd4 Signal Sd5 Control target signal Sd6 Signal Sd7 Signal Sd8 Signal Sf Current target update enable signal Sfi Original current target update enable signal Sg Gate drive signal Si Lamp current detection signal Sj Lamp current correlation signal Sk Lamp current upper limit Signal Ss Modulation enable signal Ss ′ Second modulation enable signal St Lamp current target signal Sv Lamp voltage detection signal Sxt Chopper capability control target data Sxv Lamp voltage data T11 terminal T12 terminal Tc terminal T Terminal Tm0 Terminal Tm1 Terminal Tm2 Terminal Ts Terminal Uc Lamp current upper limit signal generation circuit Ud Power supply capacity control circuit Ue Starter Ui Starter Um Original dimming signal generation circuit Un Modulation signal generation circuit Un 'Modulation signal generation circuit Un "Modulation signal generation circuit Up Power control circuit Us Data change circuit Ux Power supply circuit Uy Dimming request generation circuit VL Lamp voltage Vcc Circuit power supply Vd1 Reference voltage source Vd2 Reference voltage source Vd3 Voltage source Vd4 Offset voltage Vm Power supply Vx Lamp voltage detection means Z0 switch Z0 'switch Z0 " Switch Z0a Switch element Z0b Switch element Z1 Switch Z1 'Switch Z1 "Switch Z1a Switch element Z1b Switch element Z2 Switch Z2' Switch Z2" Switch Z2a Switch element Z2b Switch element

Claims (4)

  A discharge lamp lighting device for lighting a discharge lamp, in which a pair of electrodes for main discharge are arranged to face each other, a power supply circuit for supplying power to the discharge lamp, and detecting a lamp voltage to generate a lamp voltage detection signal A lamp voltage detection means for detecting the lamp current and generating a lamp current detection signal, a lamp current detection signal conversion circuit for converting the lamp current detection signal, and the lamp current A power supply capability control circuit that feedback-controls the power supply circuit so that a difference between a lamp current correlation signal from a detection signal conversion circuit and a lamp current target signal indicating a magnitude of a current flowing through the discharge lamp is reduced; and the lamp voltage The lamp current target so that the load power value supplied to the discharge lamp depending on the detection signal becomes a predetermined target power value. A power control circuit for updating the signal and a modulation signal generation circuit for generating a binary modulation signal of a plurality of bits, the lamp current detection signal conversion circuit corresponding to the true and false of each bit of the modulation signal A discharge lamp lighting device comprising: a plurality of switches whose ON state and OFF state are controlled, wherein the gain is variable by a combination of true and false of each bit of the modulation signal.   The power control circuit includes a circuit that generates a modulation permission signal that is inactive during a period from the start of lighting until the lamp voltage is stabilized, and the modulation signal generation circuit includes the modulation permission signal in an active state. When the modulation signal is inactive, a signal having a predetermined combination is generated as the modulation signal when the modulation signal is inactive. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is configured to do so.   The power control circuit does not update the lamp current target signal when the current target update permission signal generated by the external primary dimming signal generation circuit is inactive during a period when the lamp voltage is stable. The discharge lamp lighting device according to claim 2, wherein the discharge lamp lighting device is configured. The power control circuit monitors the duration of the current target update permission signal in an inactive state, and deactivates the modulation permission signal when detecting that the duration is equal to or longer than a predetermined time. The discharge according to claim 3, wherein the lamp current target signal is updated so that a load power value supplied to the discharge lamp becomes a predetermined target power value. Lamp lighting device.

Images