JP2005327661A - Lighting device of high-pressure discharge lamp, and electronic apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve an inconvenience of brightness change happening at the time of switching, while it is necessary to switch alternate current for restraining lamp flicker when brightness is smoothly varied at lighting of a high-pressure discharge lamp. <P>SOLUTION: The lighting device has a structure of variably controlling power supplied to the high-pressure discharge lamp by an arbitrary voltage, and changing amplitudes of a plurality of stepped waves in such waveforms that the wave form of the alternate current increases after commutation of rectangular waves until commutation of a plurality of stepped waves by an arbitrary voltage, and constantly controlling an average current of the alternate current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting device for a high-pressure discharge lamp that applies a high-pressure pulse at the time of starting, such as a high-pressure mercury lamp or a metal halide lamp, and an electronic apparatus such as a data projector using the same.

  Conventionally, a discharge arc has become unstable during lighting of a high-pressure discharge lamp (hereinafter referred to as a discharge lamp), and flicker has occurred in the discharge lamp. This is due to the movement of the starting point of the discharge arc. As a cause of this, when operating with an alternating current, the anode starting point is relatively large in the discharge in high-pressure steam due to the difference in operating mechanism between the anode and cathode of the discharge lamp. On the other hand, since the cathode starting point is very small, it is not constant where the cathode starting point can be made in the anode starting point. It is necessary to stabilize the starting point.

  FIG. 10 is a waveform diagram of AC voltage, AC current, and power supplied to the discharge lamp of a lighting device having a conventional discharge lamp. The peak value of the AC voltage (Vla) is fixed by the discharge voltage of the discharge lamp. The electric power supplied to the discharge lamp is controlled by alternating current (Ila).

  Here, as a countermeasure against flicker, the AC current of the discharge lamp is gradually increased in a half cycle (time t0 to t1) of the AC current as shown in FIG. 10-2.

  The current is gradually increased to the negative side also in the negative half cycle (time t1 to t2) of the alternating current.

  As a result, as shown in FIG. 10-3, the discharge lamp power can be maximized immediately before the polarity inversion of the half cycle of the alternating current (time t1), and the temperature of the electrode of the discharge lamp is high immediately before the polarity inversion. In this lighting method, the discharge arc is generated from the same location and the stability of the discharge arc is increased to control the flicker of the high pressure discharge lamp.

  Here, in an electronic apparatus such as a data projector using a high pressure discharge lamp as a light source, normally, 130 W of power supplied to the high pressure discharge lamp is supplied by using the maximum brightness of the high pressure discharge lamp. As shown in the waveform at the time of maximum power shown in FIG. 10-2- (a), in the half cycle of the alternating current (time t0 to t1), the rate of increase of the alternating current with the passage of time decreases. When the room is darkened and the brightness of the high pressure discharge lamp of the data projector is set to the minimum (energy saving mode or the like), the screen becomes easy to see and energy saving is achieved. At this time, the power supplied to the high-pressure discharge lamp is, for example, 110 W, and the above flicker is more likely to occur and is easy to feel. Therefore, the alternating current is as shown in the waveform at the minimum power shown in FIG. 10-2- (b). In the half cycle of the current (time t0 to t1), the rate at which the alternating current increases with time increases.

  When the luminance of the AC discharge lamp is maximum (power supply 130 W), flicker is not noticeable, and if the peak value of the AC current is large, the life of the high-pressure discharge lamp may be affected. Use a flicker-suppressed lighting method that changes the rate of increase.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP 2002-134287 A

  This conventional lighting method is effective when the luminance of the high-pressure discharge lamp is switched in two steps: maximum (130 W) and minimum (110 W). However, when it is desired to smoothly change the brightness of the high pressure discharge lamp from the maximum (130 W) to the minimum (110 W) according to the brightness of the screen to be projected and the brightness of the room, for example, in 16 steps, the brightness of the high pressure discharge lamp From the minimum (110 W) to the middle (120 W), the alternating current that suppresses flicker is the waveform at the time of the minimum power in FIG. 10-2- (b), and from the middle (122 W) to the maximum (130 W) The waveform at the time of maximum power in Fig. 10-2- (a) is used. However, when the luminance of the AC discharge lamp is changed from the middle level (120 W) to (122 W), the AC current increase signal that suppresses flicker is changed from FIG. 10-2- (b) to FIG. 10-2- (a). The problem is that the waveform changes greatly and the brightness changes.

  Even when the discharge lamp power is changed from 120 W to 122 W, the method of increasing the alternating current with the passage of time is an excellent method with little change as the average current. The average power will also change.

  The present invention solves the above-described conventional problems, and a lighting method for smoothly changing the luminance of a high-pressure discharge lamp with a simple circuit configuration while the high-pressure discharge lamp is lit and suppressing flicker, and an electronic device using the same An object of the present invention is to provide a long-life high-pressure discharge lamp in an apparatus.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, when the high pressure discharge lamp is lit with an alternating current, the electric power supplied to the high pressure discharge lamp is variably controlled with an arbitrary voltage, and the current value of the alternating current is a rectangular wave. After the commutation, the waveform increases to a predetermined current with a plurality of staircase waves, and then increases until the commutation with a plurality of staircase waves. A lighting device for a high pressure discharge lamp comprising a circuit for controlling the average current of the alternating current so that the electric power of the discharge lamp becomes constant and lighting the high pressure discharge lamp.

  In the lighting method of the high pressure discharge lamp according to the present invention, the luminance of the high pressure discharge lamp can be changed smoothly during the lighting of the high pressure discharge lamp, and a stable flicker reduction effect can be obtained.

  The invention according to claim 2 of the present invention controls the power supplied to the high pressure discharge lamp with an arbitrary voltage when the high pressure discharge lamp is lit with an alternating current, and the current value of the alternating current is a rectangular wave. Control the average current of the alternating current so that the power of the high-pressure discharge lamp is constant by changing the amplitude of the increasing waveform of the alternating current with an arbitrary voltage. The high pressure discharge lamp lighting device includes a circuit for lighting the high pressure discharge lamp.

  With the lighting method of the high-pressure discharge lamp according to the present invention, it is possible to reduce the change in luminance of the discharge lamp while reducing lamp flicker with a simple circuit configuration.

  According to a third aspect of the present invention, as an arbitrary voltage, a voltage obtained by integrating the PWM signal is converted into a digital signal by an A / D converter, and the digital signal is decoded to control the switch circuit. Then, the voltage dividing ratio for dividing the voltage of the high-pressure discharge lamp or a voltage proportional thereto is varied, and the high-voltage discharge is controlled by a microcomputer for controlling the flow of the current corresponding to the divided voltage to the high-pressure discharge lamp and the control signal of the microcomputer. 3. The lighting device for a high pressure discharge lamp according to claim 1, further comprising a circuit for controlling power supplied to a converter that supplies power to the electric lamp.

  According to the lighting method of the high pressure discharge lamp according to the present invention, it is possible to easily control the brightness of the discharge lamp by an external PWM signal, and an unnecessary brightness change of the discharge lamp is reduced with a simple circuit configuration while reducing lamp flicker. Can be reduced.

  According to a fourth aspect of the present invention, one end of a resistor is connected to each of a plurality of output terminals of a microcomputer that can be turned on / off for an arbitrary time, the other end of the resistor is made common, and a first constant current is provided. The first transistor, the second transistor, and the third transistor that constitute the source are connected to any one of the transistors, the output of the other two transistors, the fourth transistor that constitutes the second constant current source, and the fifth transistor A lighting device for a high pressure discharge lamp having a waveform generator connected to the output of a transistor, turning on and off a second constant current source with the microcomputer, and changing a power source of the first constant current source with an arbitrary voltage. is there.

  According to the lighting method of the high-pressure discharge lamp according to the present invention, it is possible to generate a waveform for reducing lamp flicker and easily control the amplitude of the waveform with a simple circuit configuration.

  According to the fifth aspect of the present invention, when a high pressure discharge lamp is lit with an alternating current, a waveform in which the current waveform of the alternating current gradually increases from the commutation of the rectangular wave toward the end is obtained. The voltage of the alternating current flowing through the discharge lamp is amplified to change the amplitude of the gradually increasing alternating current waveform, and the average current of the alternating current is controlled so that the electric power of the high pressure discharge lamp becomes constant. It is the lighting device of the high pressure discharge lamp provided with the circuit which lights up.

  In the lighting method of the high pressure discharge lamp according to the present invention, the amplitude of the waveform for reducing the lamp flicker is controlled in accordance with the current flowing through the discharge lamp, and if the brightness of the discharge lamp is controlled by an external voltage, the discharge corresponding thereto is controlled. The lamp current is determined and the amplitude of the flicker reduction signal can be automatically set.

  According to the sixth aspect of the present invention, when a high pressure discharge lamp is lit with an alternating current, a waveform in which the current waveform of the alternating current gradually increases from the commutation of the rectangular wave toward the end is obtained. In the control where the electric power of the discharge lamp is constant, the current control signal from the microcomputer that calculates the average current of the alternating current from the voltage of the high-pressure discharge lamp causes the current waveform of the alternating current to end after the commutation of the rectangular wave. A lighting device for a high pressure discharge lamp having a circuit for changing gradually increasing amplitude.

  In the lighting method of the high pressure discharge lamp according to the present invention, the amplitude of the waveform that reduces the lamp flicker by utilizing the fact that the control signal for making the power of the discharge lamp constant even when the discharge voltage of the discharge lamp changes is proportional to the discharge lamp current. If the luminance of the discharge lamp is controlled by an external voltage, the corresponding flicker reduction signal amplitude can be automatically set.

  According to a seventh aspect of the present invention, the lighting device for a high pressure discharge lamp according to any one of the first to sixth aspects of the present invention is used with a voltage variably controlled by a PWM signal from a second microcomputer. It is a featured electronic device.

  The second microcomputer for controlling the electronic device equipped with the high-pressure discharge lamp according to the present invention can easily control the high-pressure discharge lamp according to the present invention by the PWM signal according to the brightness of the screen projected by the electronic device and the brightness of the room. In addition, it is possible to control the luminance of the discharge lamp, and with a simple circuit configuration, it is possible to reduce unnecessary flickering of the discharge lamp while reducing lamp flicker.

  The present invention variably controls the power supplied to the high pressure discharge lamp with an arbitrary voltage when the high pressure discharge lamp is lit with an alternating current, and the current waveform of the alternating current has a plurality of steps after the commutation of the rectangular wave. A waveform that increases with the wave and increases until the commutation, and changes the amplitude of the plurality of staircase waves with an arbitrary voltage, and turns on the high-pressure discharge lamp by controlling the average current of the alternating current to be constant This is a device that smoothly changes the brightness of high-pressure discharge lamps with a simple circuit configuration, reduces lamp flicker, and reduces unnecessary changes in brightness of the discharge lamp. Electronic equipment using this high-pressure discharge lamp is There is an effect that it is possible to provide life extension.

  FIG. 1 is a block diagram showing a configuration of a high pressure discharge lamp lighting device according to the present invention. The basic part of the high pressure discharge lamp lighting device of FIG. 1 is connected to the high pressure discharge lamp 11 from the DC power source 1 through a DC-DC converter 50 and an AC conversion circuit 51. The DC-DC converter 50 converts the voltage of the DC power source 1 into a high frequency voltage of several tens of KHz by a PWM control signal 58 from the control circuit 14 and obtains an output voltage to the high pressure discharge lamp. The control circuit 14 controls the output current supplied to the high pressure discharge lamp 11 to be variable.

  Here, the igniter 6 for lighting the high-pressure discharge lamp 11 by first applying a high voltage (about 20 KV) is connected to the high-pressure discharge lamp 11 via the AC conversion circuit 51.

The AC conversion circuit is composed of four switching elements, and each switching element is switched and controlled by a drive circuit 52 to supply AC power to the high-pressure discharge lamp. From the lighting waveform generation circuit 18, a rectangular wave signal 24 of several tens to several hundreds Hz is output and processed by the drive circuit 52 into an AC conversion drive signal. Further, the lighting waveform generation circuit 18 outputs a step signal 18os for reducing the flicker of the high pressure discharge lamp and an output power control signal 18oc for the high pressure discharge lamp. The amplifier 34 is an amplifier whose amplification factor varies depending on the voltage of the power source 32, and changes the amplitude of the staircase signal 18os to output a staircase variable signal 34os. The control circuit 14 compares the combined signal of the two signals 34 os and 18 oc with the output current of the discharge lamp detected by the resistor 23 to obtain a PWM control signal 58.
And
Discharge lamp current (Ila) = Discharge lamp power (Pla) / Discharge lamp voltage (Vla)
Therefore, if the proportionality constant is α, the discharge lamp output power control signal 18 oc = α × discharge lamp current (Ila) = α × (Pla / Vla)
Thus, the power of the discharge lamp 11 can be controlled to be constant and the brightness can be kept constant.

  FIG. 7 shows an operating characteristic diagram of the discharge lamp output power control signal 18 oc and the discharge lamp average current with respect to the discharge lamp voltage 55.

  The power variable circuit 70 has a function of varying the discharge lamp power by dividing the voltage 55 applied to the discharge lamp voltage (Vla) and varying the divided voltage input to the lighting waveform generation circuit 18.

(Embodiment 1)
Hereinafter, the first and second embodiments of the present invention will be described in the first embodiment. 2 is a circuit configuration diagram of the discharge lamp according to Embodiment 1 of the present invention, and FIG. 3 is an operation waveform diagram showing the operation thereof.

  In FIG. 2, the discharge lamp 11 is connected from the DC power source 1 through a DC-DC converter 50 and an AC conversion circuit 51. The DC-DC converter 50 includes a switching element 2, a PWM circuit 12, a diode 3, a choke coil 4, and a smoothing capacitor 5. The switching element 2 is turned on at a high frequency of several tens of KHz by a drive signal from the PWM circuit 12. It is turned off to convert the voltage of the DC power source 1 into a high frequency voltage of several tens of KHz, and is smoothed by the diode 3, the choke coil 4 and the smoothing capacitor 5. The PWM circuit 12 is controlled by a control circuit 14.

  The control circuit 14 connects the resistor 14b, the resistor 14d, and the high-pressure discharge lamp current detection resistor 23 in series from the reference power source 59 and grounds the other end thereof, and connects the resistor 14a and the resistor 14c in series from the reference power source 59 to the other end. It consists of a bridge circuit that grounds.

  Then, the staircase signal 18os for reducing the lamp flicker from the waveform generating circuit 18 is changed in amplitude by the amplifier 34 according to the voltage of the power supply 32 to generate the staircase variable signal 34os, and the lamp output power control signal 18oc is connected to the resistor 15. The signals are synthesized by the resistor 16 and input to the intersection of the resistors 14a and 14c.

  Further, the output voltage 55 (substantially equal to the discharge lamp voltage) of the DC-DC converter 50 is divided by the resistors 18e and 18f in the lighting waveform generation circuit 18 and input to the A / D converter 18d. From the output of the A / D converter 18d, the microcomputer 18a calculates an output value to the D / A converter 18c from the following (Equation 1) so that an optimum current can be supplied to the discharge lamp 11, and calculates the discharge lamp output power control signal 18oc. obtain.

Discharge lamp output power control signal 18 oc = α × discharge lamp current (Ila) = α × (Pla / Vla)
(Formula 1)
The voltage Vad input to the A / D converter 18d is assumed that the resistance values of the resistors 18e, 18f, and 18g are R18e, R18f, and R18g, respectively.
Vad = R18f / (R18e + R18f) × Vla (Formula 2)
When R18g is connected in parallel with R18f, the Vad voltage of Equation 2 is lowered, and the microcomputer 18a determines that Vla is lowered via the A / D converter 18d, and increases the current flowing to the discharge lamp 11, The electric power supplied to the discharge lamp 11 increases. Therefore, the power variable circuit 70 reads the voltage of the power supply 32 with an A / D converter, turns on and off the transistors 72 and 75 in the decoder circuit, and connects the resistors 73 and 74 in parallel with the resistor 18f to connect the discharge lamp voltage (Vla). ) Is further divided, and the discharge lamp power is varied by the microcomputer 18a.

  A step signal 18os for reducing lamp flicker is generated from the D / A converter 18s by the output signal of the microcomputer 18a. The amplitude of the step signal 18os is changed by the voltage of the power source 32 by the amplifier 34, and the step variable signal 34os is converted from voltage to current. Then, a signal current is passed through the resistor 14c of the bridge circuit.

  In the control circuit 14, the combined signal of the two signals 34 os and 18 oc and the lamp output current detected by the resistor 23 are input to the bridge circuit, and the intersection of the resistor 14 a and the resistor 14 c is connected to the + input of the comparator 13. When the intersection of 14b and resistor 14d is connected to the negative input of the comparator 13, and the lamp output current is small, the PWM control signal 58, which is the output of the comparator 13, rises, the conduction period of the switching element 2 becomes long, and AC conversion Control is performed so that the power supplied to the circuit 51 increases and the lamp output current increases.

  Here, the crossing voltage of the resistors 14a and 14c and the crossing voltage of the resistors 14b and 14d of the bridge circuit are set to half or less of the voltage of the power source 59. As a result, a negative power source is not required for the power source of the comparator 13 and can be shared with the power source 59. Further, the resistor 57a and the capacitor 57b that feed back the output of the comparator 13 can be connected to the bridge circuit, so that the control can be stabilized.

  The AC conversion circuit 51 includes four switching elements 7, 8, 9, and 10 and inverter circuits 19 and 20 in a drive circuit 52. The switching elements 7, 8, 9, and 10 are connected in series, respectively. The high pressure discharge lamp 11 is connected to the connection points of the switching elements 7 and 8 and the connection points 9 and 10 via the igniter 6. These switching elements 7, 8, 9, and 10 are driven by driving elements U1, U2, U3, and U4, respectively. The drive elements U2 and U4 and the drive elements U1 and U3 have output polarities opposite to each other, and the switching circuit 7 and the switching element 8 and the switching element 9 and the switching element 10 are dead in the timing circuit 21 so as not to conduct simultaneously. Time is provided. The timing circuit 21 outputs a rectangular wave signal 24 of several tens to several hundreds Hz from the microcomputer 18 a in the lighting waveform generation circuit 18, is processed into an AC conversion drive signal by the drive circuit 52 described above, and is converted by the AC conversion circuit 51. The discharge lamp 11 is continuously turned on.

  FIG. 3 is an AC drive waveform diagram of the discharge lamp 11. 3A is an AC voltage waveform applied to the high-pressure discharge lamp 11, and FIG. 3B is an AC current waveform flowing through the high-pressure discharge lamp 11. The average current (at the minimum) is the amplitude of the lamp flicker reduction signal. Fig. 3-2- (b) shows the waveform when the power is minimum, and the average current (maximum time) has the small amplitude of the lamp flicker reduction signal and becomes the waveform when the power is maximum shown in Fig. 3-2- (a). . The amplitude and average current of the ramp flicker reduction signal can be gradually changed between the minimum and maximum.

  The functions of the power variable circuit 70 described above can be rationalized by incorporating them into the microcomputer 18a.

  According to the second aspect of the present invention, the ramp flicker reduction linearly increases as shown in the alternating current of FIG. 3 by increasing the output with time by the D / A converter 18s for generating the staircase signal 18os for reducing the lamp flicker from the waveform generation circuit 18. A signal is obtained. However, this method requires a long time for processing software in the microcomputer 18a. Therefore, there is a method of creating a sawtooth signal by passing a constant current through the capacitor.

(Embodiment 2)
Hereinafter, in the second embodiment, the invention described in claims 3 and 4 of the present invention will be described. FIG. 4 is a circuit configuration diagram of the simplified D / A converter 18sa, the microcomputer 18a, and the power variable circuit 70 in the lighting waveform generation circuit 18, particularly of the high pressure discharge lamp according to the second embodiment of the present invention. FIG. 5 is an operation waveform diagram showing the operation.

  In FIG. 4 in the present embodiment, a PWM signal for controlling the luminance from the microcomputer 91 in the electronic apparatus incorporating the high pressure discharge lamp lighting device of the present invention is sent to the high pressure discharge lamp lighting device of the present invention via the photocoupler 90. The PWM signal 60 is input. The PWM signal 60 is integrated by a resistor 61 and a capacitor 62, converted into a DC voltage, and applied to an amplifier 63 and a terminal A / D1 of the microcomputer 18a. First, the microcomputer 18a turns on and off the transistor 72, the transistor 75, and the transistor 18h according to the voltage obtained at the terminal A / D1 of the microcomputer 18a, and the resistor 18e and the resistor 18f that divide the voltage 55 of the discharge lamp 11. Furthermore, a resistor 73, a resistor 74, and a resistor 18g are connected in parallel to generate a divided voltage Vad corresponding to the PWM signal 60. The microcomputer 18a controls the power supplied to the discharge lamp 11 according to the divided voltage Vad. In the embodiment, since the three resistors are turned on / off, the brightness can be changed to 8 gradations of 2 × 2 × 2 = 8.

  Then, the microcomputer 18a turns on and off the terminals P1, P2, and P3 for an arbitrary time, and causes a current to flow through the transistor 35 and the resistor 31 through the resistors 39a, 39b, and 39c (FIG. 5- (a)). Transistors 35, 35a and 35b constituting the first constant current source are connected to outputs (current discharge) and transistors 37 and 36 constituting the second constant current source are connected to outputs (current sink). When the transistor 39 is turned on from the terminal P4 of the microcomputer 18a (FIG. 5- (b): switch switching signal 18sc), the second constant current source has twice the current of the first constant current source. Is set to suck in, the output staircase signal 34osa becomes a sucking current (negative staircase wave) as shown in FIG. 5- (c): t0 to t8.

  Next, when the transistor 39 is turned off from the terminal P4 of the microcomputer 18a (FIG. 5- (b): switch switching signal 18sc), the staircase signal 34osa is discharged as shown in (FIG. 5- (c): t8 to t15). (Positive staircase).

  The DC voltage obtained by integrating the PWM signal 60, which is a control signal, with the resistor 61 and the capacitor 62 is supplied to the amplifier 63 (buffer) as the power source of the first constant current source, so that the resistance is changed according to the change of the PWM signal 60. The current flowing through 31 changes, and the amplitude of the staircase signal 34 osa in FIG.

  The resistors 39a, 39b, and 39c can increase the staircase waveform of the staircase signal 34osa linearly or parabolically depending on the resistance values.

(Embodiment 3)
Hereinafter, in the third embodiment, the invention described in claim 5 of the present invention will be described. FIG. 6 is a circuit configuration diagram of the high pressure discharge lamp according to the third embodiment. FIG. 7 is an operation characteristic diagram of the high pressure discharge lamp. When the discharge lamp voltage 55 changes linearly, the discharge lamp power is constant at 130 W. As a result, the discharge lamp average current is an inversely proportional curve.

  In FIG. 6, the electric power supplied to the high pressure discharge lamp 11 through the AC conversion circuit 51 lights the high pressure discharge lamp with an AC current, and the control circuit from the AC conversion circuit 51 through the discharge lamp current line (DC current) 56. The current is passed through the current detection resistor 23 in 14. Therefore, a voltage proportional to the discharge lamp current is generated in the discharge lamp current line. When the voltage is amplified by inverting amplifier 80 with the voltage increase / decrease reversed, a high voltage is obtained when the discharge lamp current is small, and a low voltage is obtained when the discharge lamp current is large. As described in the first embodiment, the output (voltage) of the amplifier 34 is changed by the output voltage of the inverting amplifier 80 to generate the step variable signal 34os, thereby smoothly changing the current (luminance) of the high-pressure discharge lamp and flickering. The reduction signal also changes smoothly.

(Embodiment 4)
Hereinafter, in the fourth embodiment, the invention described in claim 6 of the present invention will be described. FIG. 8 is a circuit configuration diagram of the high pressure discharge lamp according to the fourth embodiment, and FIG. 7 is an operation characteristic diagram of the high pressure discharge lamp.

  In the circuit configuration diagram of FIG. 8, the basic operation is the same as that of FIG.

  The difference between FIG. 8 and FIG. 2 is that in FIG. 2, the staircase signal 18os for reducing the lamp flicker from the waveform generation circuit 18 changes the output amplitude of the amplifier 34 according to the voltage of the power supply 32 and outputs the staircase variable signal 34os. On the other hand, in FIG. 8, a voltage obtained by amplifying the output voltage of the D / A converter 18c by the inverting amplifier 81 is applied as a voltage for changing the output amplitude of the amplifier 34, and the step variable signal 34os is output.

As explained at the beginning of the embodiment of the invention, the discharge lamp output power control signal 18 oc = α × discharge lamp current (Ila) = α × (Pla / Vla)
Thus, the power of the discharge lamp 11 can be controlled to be constant, and the brightness can be kept constant. FIG. 7 shows an operating characteristic diagram of the discharge lamp output power control signal 18 oc and the discharge lamp average current with respect to the discharge lamp voltage 55.

  Therefore, the voltage obtained by inverting and amplifying the output voltage of the D / A converter 18c becomes a low voltage when the discharge lamp average current is large, and when applied to the amplifier 34, the step variable signal 34os becomes small, and the output voltage of the D / A converter 18c is inverted. The output voltage of the amplifier 81 to be amplified becomes a low voltage when the discharge lamp average current is large, and when applied to the amplifier 34, the step variable signal 34os becomes small. Conversely, when the discharge lamp average current is small, the output of the amplifier 81 becomes a high voltage, and when applied to the amplifier 34, the step variable signal 34os becomes large.

  That is, when the current (brightness) of the high-pressure discharge lamp is smoothly changed by changing the output of the amplifier 34 by the output voltage of the inverting amplifier 81 and generating the staircase variable signal 34os, the flicker reduction signal also changes smoothly. .

(Embodiment 5)
Hereinafter, in the fifth embodiment, the invention described in claim 7 of the present invention will be described. FIG. 9 is a circuit configuration diagram of the high-pressure discharge lamp in the fifth embodiment.

  In the circuit configuration diagram of FIG. 9, the basic operation is the same as that of FIG.

  Here, if the output of the amplifier 34 is changed by the voltage of the discharge lamp output power control signal 18 oc that is the output of the D / A converter 18 c without inverting the inverting amplifier 81 to generate the step variable signal 34 os, the current of the high-pressure discharge lamp A flicker reduction signal proportional to (luminance) is obtained, and the use of correcting the brightness of the upper and lower parts of the screen in synchronization with the alternating current of the discharge lamp 11 is possible while reducing flicker.

(Embodiment 6)
Hereinafter, in the sixth embodiment, the invention described in claim 8 of the present invention will be described. Although the sixth embodiment has been described in the second embodiment, in FIG. 4, the PWM signal for controlling the luminance is transmitted via the photocoupler 90 from the microcomputer 91 in the electronic device incorporating the high pressure discharge lamp lighting device of the present invention. The PWM signal 60 is input to the high pressure discharge lamp lighting device of the present invention. The PWM signal 60 is integrated by a resistor 61 and a capacitor 62, converted into a DC voltage, and applied to an amplifier 63 and a terminal A / D1 of the microcomputer 18a. First, the microcomputer 18a turns on / off the transistor 72, the transistor 75, and the transistor 18h according to the voltage obtained at the terminal A / D1 of the microcomputer 18a, and controls the luminance of the discharge lamp 11. Further, the amplitude of the lamp flicker reduction signal can be smoothly changed according to the luminance by controlling the amplitude of the signal of the lamp flicker reduction by the variable amplitude amplifier by the PWM signal 60.

  Therefore, the second microcomputer for controlling the electronic device equipped with the high-pressure discharge lamp according to the present invention outputs the PWM signal according to the present invention as a PWM signal according to the brightness of the screen projected by the electronic device or the brightness of the room. Therefore, it is possible to easily control the luminance of the discharge lamp, and it is possible to reduce unnecessary luminance change of the discharge lamp while reducing lamp flicker with a simple circuit configuration.

  The present invention is suitable for a lighting device for applying a high-pressure pulse when starting a high-pressure discharge lamp such as a high-pressure mercury lamp or a metal halide lamp, and an electronic apparatus such as a data projector using the same.

1 is a block diagram of an electronic device according to Embodiment 1 of the present invention. 1 is a circuit configuration diagram of an electronic device according to Embodiment 1 of the present invention. Operation waveform diagram of electronic device in Embodiment 1 of the present invention The circuit block diagram of the electronic device in Embodiment 2 of this invention Operation Waveform Diagram of Electronic Device in Embodiment 2 of the Present Invention The circuit block diagram of the electronic device in Embodiment 3 of this invention Operation characteristic diagram of electronic device in Embodiment 3 of the present invention The circuit block diagram of the electronic device in Embodiment 4 of this invention Circuit configuration diagram of electronic device according to Embodiment 5 of the present invention Operation waveform diagram of electronic device in conventional example

Explanation of symbols

1, 32, 64 DC power supply 2, 7, 8, 9, 10 Switching element 6 Igniter 11 High pressure discharge lamp (lamp)
13 Comparator 14, 54 Control circuit 18, 53 Lighting waveform generation circuit 18c, 18s, 18sa D / A converter 18a, 91 Microcomputer 24 Rectangular wave signal 34, 63 Amplifier 50 DC-DC converter 51 AC conversion circuit 52 Drive circuit 58 PWM control signal 60 PWM signal 70 Variable power circuit 80, 81 Inverting amplifier

Claims (7)

When lighting a high pressure discharge lamp with an alternating current, the electric power supplied to the high pressure discharge lamp is variably controlled with an arbitrary voltage, and the current value of the alternating current is a predetermined current with a plurality of step waves after the commutation of a rectangular wave. The AC voltage is increased so that the amplitude of the plurality of staircase waves is changed by an arbitrary voltage so that the power of the high-pressure discharge lamp becomes constant. A high pressure discharge lamp lighting device comprising a circuit for controlling an average current and lighting a high pressure discharge lamp. When lighting the high pressure discharge lamp with an alternating current, the power supplied to the high pressure discharge lamp is controlled by an arbitrary voltage, and the current value of the alternating current gradually increases from the commutation of the rectangular wave toward the end. The circuit includes a circuit for changing the amplitude of the waveform of the alternating current to increase by an arbitrary voltage, controlling the average current of the alternating current so that the power of the high pressure discharge lamp becomes constant, and lighting the high pressure discharge lamp. High pressure discharge lamp lighting device. As an arbitrary voltage, a voltage obtained by integrating the PWM signal is converted into a digital signal by an A / D converter, the digital signal is decoded, the switch circuit is controlled, and the voltage of the high-pressure discharge lamp or a voltage proportional thereto The supply voltage of the microcomputer that controls the flow of the current corresponding to the divided voltage to the high-pressure discharge lamp and the converter that supplies power to the high-pressure discharge lamp is controlled by the control signal of the microcomputer. The lighting device for a high pressure discharge lamp according to claim 1, further comprising a circuit for performing the operation. One end of a resistor is connected to each of a plurality of output terminals of a microcomputer that can be turned on / off for an arbitrary time, the other end of the resistor is made common, and the first transistor and the second transistor constituting the first constant current source Connected to one of the transistor and the third transistor, and connected to the output of the other two transistors and the output of the fourth transistor and the fifth transistor constituting the second constant current source, the second constant current A high-pressure discharge lamp lighting device having a waveform generator in which a power source of a first constant current source is varied at an arbitrary voltage by turning on and off a source with the microcomputer. When the high pressure discharge lamp is lit with alternating current, the waveform of the alternating current gradually increases from the commutation of the rectangular wave toward the end, and the average current of the alternating current flowing through the high pressure discharge lamp is amplified. Lighting of the high-pressure discharge lamp with a circuit for changing the amplitude of the gradually increasing alternating current waveform according to the voltage and controlling the average current of the alternating current so that the power of the high-pressure discharge lamp becomes constant and lighting the high-pressure discharge lamp apparatus. When lighting a high-pressure discharge lamp with an alternating current, a waveform in which the current waveform of the alternating current gradually increases from the commutation of the rectangular wave toward the end of the high-pressure discharge lamp is controlled in the control where the power of the high-pressure discharge lamp is constant. With a current control signal from a microcomputer that calculates the average current of the alternating current from the voltage of the lamp, a circuit is provided that changes the amplitude of the alternating current waveform gradually increasing from the commutation of the rectangular wave toward the end. High pressure discharge lamp lighting device. 7. An electronic apparatus comprising: a lighting device for a high-pressure discharge lamp according to claim 1 that is variably controlled by a PWM signal from a second microcomputer.

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