JP2008140657A - Discharge lamp lighting device, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of achieving safety and downsizing of a device and controlling power more finely. <P>SOLUTION: A transformer 6 and a photo coupler 5 are installed to secure insulation between a primary side circuit part 10 connected to an AC power supply and a secondary side circuit part 20 to impress voltage on a lamp 4. An auxiliary converter 71 impresses voltage converted by a first winding 621 and a second winding 622 on the lamp 4 from the beginning of starting of the lamp 4 till a prescribed time. A detection circuit part 22E installed at the secondary side circuit part 20 detects the output voltage and output current of the lamp 4 and detects a deviation from the prescribed power. A signal corresponding to the variation detected by the detection circuit part 22E is transmitted to the primary side circuit part 10 through the photo coupler 5 installed between the primary side circuit part 10 and the secondary side circuit part 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp such as a metal halide lamp or a high pressure mercury lamp, and a projector including the discharge lamp lighting device.

  Conventionally, there is a projection display device (projector) that projects light and displays an image on a screen, and a discharge lamp such as a metal halide lamp is used as a light source of the projector. A discharge lamp lighting device for performing is used. A conventional discharge lamp lighting device is disclosed in Patent Document 1, for example. FIG. 16 is a circuit diagram showing a configuration of a conventional discharge lamp lighting device. In FIG. 16, reference numeral 100 denotes a conventional discharge lamp lighting device, which includes a line filter 102 connected to an AC power source 101, a rectifier bridge 103, a step-up converter 104, a step-down converter 105, and an igniter 106 that operates when the lamp 107 is started up. . Boost converter 104 converts a commercial AC power source into a direct current, and thus may be referred to as a “power source” in combination with line filter 102 and rectifier bridge 103. Further, when the converter has a switching regulator type configuration, the step-down converter 105 is sometimes called a “step-down chopper” because it controls the current or voltage by chopping. Similarly, the boost converter may be called a boost chopper. The rectifier bridge 103 includes four diodes and may be referred to as a diode bridge.

  The step-down converter 105 is sometimes called a ballast because it controls the product of the voltage across the lamp 107 and the flowing current to be constant. The lamp 107 has a rated value of input power, for example, 200 W ± 10%. On the other hand, since the voltage at both ends of the lamp 107 varies depending on the lifetime, the input power can be kept within a certain range by controlling the amount of current. . Further, the lamp 107 generally includes an AC lamp in which the potentials of two electrodes alternate at a constant cycle and a DC lamp in which the potential polarity is always constant. In FIG. 16, the DC system lamp is turned on. For example, an inverter composed of four FETs is provided between the step-down converter 105 and the igniter 106, and the direct-current output of the step-down converter 105 is converted into alternating current. It becomes possible to correspond to the lamp.

The AC of 100V to 240V output from the AC power supply 101 is rectified by the rectifier bridge 103 via the line filter 102, and a peak voltage (144V to 340V) approximately √2 times is generated at the output of the rectifier bridge 103. Then, the boost converter 104 boosts the peak voltage to DC 370V to 400V. The step-down converter 105, which is a ballast, steps down the voltage so as to be 100V to 200V during glow discharge of the lamp 107, 15V during initial arc discharge, and 60V during steady arc discharge. The igniter 106 is a circuit used in the case of dielectric breakdown of the lamp 107, and the igniter 106 operates when the open circuit voltage, which is the output of the step-down converter 105, is in a state of 200V to 300V. The igniter 106 generates a voltage of approximately several kilovolts to several tens of kilovolts, causes dielectric breakdown in the discharge lamp internal gas, and starts it.
JP-A-9-320772

  However, since the conventional discharge lamp lighting device described in Patent Document 1 includes two boost converters and step-down converters, there is a problem in that power loss increases and the structure increases in size. Moreover, since the high-intensity discharge lamp lighting device described in the discharge lamp lighting device described in Patent Document 1 is a non-insulating structure, it is necessary to manage the live parts in each part. Therefore, the necessary insulation treatment is required at various places of the high-intensity discharge lamp lighting device and the lamp, and as a result, there is a problem that the entire device becomes large.

  Further, unlike a discharge lamp lighting device applied to an automobile headlamp or the like, a discharge lamp lighting device applied to a projector needs to suppress residual AC ripple that causes flicker. That is, an AC voltage is supplied to a discharge lamp lighting device applied to a projector, which causes a ripple current or a ripple voltage, and causes a flicker when displayed on a screen or the like.

  Further, in order to light the discharge lamp, it is necessary to generate a high voltage and shift the discharge lamp to dielectric breakdown and glow discharge. Therefore, the converter must cover a wide voltage, and each electric element used in the converter is required to be able to withstand high voltage. As a result, it is difficult to reduce the size of the device, and further, It was a factor that hindered efficiency.

  The present invention has been made in view of such circumstances, and the object thereof is to insulate the secondary side circuit unit from the primary side circuit unit, and based on the lamp current and the lamp voltage in the secondary side circuit unit. By performing constant power control by comparing the power with a predetermined target power, the safety and size of the device can be reduced, and more precise power control of the lamp can be achieved, and the commercial AC voltage can be achieved with a single-stage converter configuration. It is intended to provide a discharge lamp lighting device that performs constant power control that is indispensable to a lamp while converting the voltage into a DC voltage, and a projector using the discharge lamp lighting device.

  Another object of the present invention is to apply a voltage converted by the first winding and the second winding of the transformer from the start of the discharge lamp to the discharge lamp from the start of the discharge lamp to the discharge lamp by the auxiliary circuit to satisfy the predetermined condition. After that, a voltage converted by the first winding is applied to the discharge lamp by the main circuit, so that the discharge lamp lighting device can be reduced in size and increased in efficiency, and a projector using the discharge lamp lighting device Is to provide.

  A discharge lamp lighting device according to the present invention is a discharge lamp lighting device for lighting a discharge lamp, and a primary side circuit unit connected to a power supply device, and a transformer connected to the primary side circuit unit for converting a voltage; A secondary circuit part connected to the transformer for applying the converted voltage to the discharge lamp, and provided in the secondary circuit part, and detecting an output voltage and an output current of the discharge lamp, A detection circuit unit that detects a deviation from electric power, and a signal corresponding to the deviation detected by the detection circuit unit is provided between the primary circuit unit and the secondary circuit unit. A signal transmission element that transmits to the power supply unit, and a switching control unit that is provided in the primary side circuit unit and that performs switching control related to constant power lighting based on the signal transmitted from the signal transmission element. The secondary winding includes a first winding and a second winding The secondary circuit section includes an auxiliary circuit that applies a voltage converted by the first winding and the second winding to the discharge lamp until a predetermined condition is satisfied after starting the discharge lamp, and the predetermined circuit And a main circuit for applying the voltage converted by the first winding to the discharge lamp after satisfying the condition.

  In the discharge lamp lighting device according to the present invention, the auxiliary circuit includes a diode connected to one end of the second winding, a capacitor connected to a cathode of the diode, and supplies a charged voltage to the discharge lamp; And a switch connected to the cathode of the diode and the capacitor.

  In the discharge lamp lighting device according to the present invention, the main circuit is connected to the other end of the second winding and the one end of the first winding having a common output end, and to the cathode of the diode. And a capacitor for supplying the charged voltage to the discharge lamp.

  The discharge lamp lighting device according to the present invention further includes a diode connected to the output of the main circuit and a diode connected to the output of the auxiliary circuit, and a cathode of the diode connected to the output of the main circuit; The cathodes of the diodes connected to the output of the auxiliary circuit are connected to each other.

  In the discharge lamp lighting device according to the present invention, the diode connected to the output of the main circuit and the diode connected to the output of the auxiliary circuit are rated specifications with a high withstand voltage for preventing a high voltage generated in the igniter. It is characterized by being.

  The discharge lamp lighting device according to the present invention turns on the switch at the start of starting the discharge lamp, supplies power to the discharge lamp from the auxiliary circuit, and turns off the switch after the predetermined condition is satisfied. It is characterized by doing.

  In the discharge lamp lighting device according to the present invention, the predetermined condition is that a predetermined time elapses, and the auxiliary circuit includes the first winding and the first winding until the predetermined time elapses after starting the discharge lamp. The main circuit is configured to apply a voltage converted by the second winding to the discharge lamp, and the main circuit passes the voltage converted by the first winding to the discharge lamp after the predetermined time has elapsed. It is comprised so that it may apply.

  In the discharge lamp lighting device according to the present invention, the predetermined condition is that a voltage of a capacitor of the main circuit is equal to or lower than a predetermined voltage value, and the auxiliary circuit The voltage converted by the first winding and the second winding is applied to the discharge lamp until the voltage of the capacitor becomes a predetermined voltage value or less, and the main circuit is a capacitor of the main circuit. After the voltage becomes less than a predetermined voltage value, the voltage converted by the first winding is applied to the discharge lamp.

  In the discharge lamp lighting device according to the present invention, the predetermined condition is that a current related to the discharge lamp is equal to or greater than a predetermined current value, and the auxiliary circuit is related to the discharge lamp after starting the discharge lamp. The voltage converted by the first winding and the second winding is applied to the discharge lamp until the current becomes equal to or higher than a predetermined current, and the main circuit has a predetermined current for the discharge lamp. The voltage converted by the first winding is applied to the discharge lamp after the current becomes equal to or higher than the current.

  The discharge lamp lighting device according to the present invention includes means for turning off the switch when the amount of electricity related to the discharge lamp exceeds a predetermined value within the predetermined time from the start of starting the discharge lamp; And a means for turning on the switch again when the amount of electricity related to the discharge lamp exceeds a value different from the predetermined value after the switch is turned off.

  In the discharge lamp lighting device according to the present invention, the primary side circuit unit is a self-excited flyback converter.

  In the discharge lamp lighting device according to the present invention, the signal transmission element is a photocoupler.

  A projector according to the present invention includes any one of the above-described discharge lamp lighting devices.

  In the present invention, a transformer and a signal transmission element are provided in order to ensure insulation between the primary side circuit unit connected to the power supply device and the secondary side circuit unit that applies a voltage to the discharge lamp. . The detection circuit unit provided in the secondary circuit unit detects the output voltage and the output current of the discharge lamp, and detects a current deviation so as to obtain a predetermined power. A signal corresponding to the deviation detected by the detection circuit unit is transmitted to the primary circuit unit via a signal transmission element such as a photocoupler provided between the primary circuit unit and the secondary circuit unit. Is done. And since the switching control part provided in a primary side circuit part performs switching control which concerns on constant power lighting based on the signal transmitted from the signal transmission element, it performs control based on detection of both a lamp current and a lamp voltage. For example, finer power control is possible at the end of the lamp life.

  Since the secondary side circuit unit is insulated from the primary side circuit unit connected to the power supply device, the electric shock of the discharge lamp caused by the primary side power supply device can be eliminated and the insulation distance can be reduced. It becomes possible to reduce the size of the apparatus. The lamp is fixed to a bowl-shaped structure called a reflector for condensing output light. For example, when the reflector is made of a conductive metal such as aluminum, it is insulated if the lamp is on the secondary side. No structure is required, which is advantageous for downsizing.

  The secondary winding of the transformer is composed of a first winding and a second winding, and the secondary circuit portion is composed of a main circuit and an auxiliary circuit. The auxiliary circuit applies the voltage converted by the first winding and the second winding to the discharge lamp until the predetermined condition is satisfied from the start of the discharge lamp. This auxiliary circuit includes, for example, a diode connected to one end of the second winding, a capacitor connected to the cathode of the diode, and supplies a charged voltage to the discharge lamp, and a switch connected to the cathode and the capacitor of the diode. Is done. For example, the switch cuts off the voltage supply to the discharge lamp by the capacitor after a predetermined time has elapsed since the start of the discharge lamp.

  After satisfying a predetermined condition, the main circuit applies the voltage converted by the first winding to the discharge lamp. This main circuit is composed of, for example, a diode connected to the other end of the second winding having a common output end, one end of the first winding, and a capacitor connected to the cathode of the diode. The voltage charged in the capacitor is supplied to the discharge lamp.

  In the present invention, the discharge lamp lighting device turns off the switch when the amount of electricity related to the discharge lamp exceeds a predetermined value within the predetermined time from the start of starting the discharge lamp. That is, when the current flowing through the discharge lamp is equal to or greater than a predetermined value or when the voltage applied to the discharge lamp is equal to or less than the predetermined voltage, it is determined that the arc discharge has been started, the switch is turned off, and the auxiliary circuit is switched to the main circuit Switch. Then, after the switch is turned off, the switch is turned on again when the amount of electricity related to the discharge lamp exceeds a value different from the predetermined value. In other words, if the discharge lamp is extinguished due to a special arc or the like after switching to the main circuit, the switch is turned on again to switch to the auxiliary circuit.

  In the present invention, a self-excited flyback converter is used for the primary side circuit unit, switching control is performed based on the signal transmitted from the secondary side circuit unit, and constant power lighting of the discharge lamp is performed. Do. In other words, since the primary side self-excited flyback converter and the detection circuit unit for detecting the secondary side power deviation are combined to perform constant power control of the discharge lamp, the converter can be configured as a single device. Can be miniaturized. In addition, since the secondary circuit unit detects a deviation from the target power and performs constant power control, the influence of the ambient temperature of the discharge lamp lighting device and individual differences of members can be reduced, and the error of output power can be reduced. Furthermore, it is possible to suppress the influence of residual AC ripple that causes flicker in a projector using a discharge lamp.

  In the present invention, the primary side circuit unit and the secondary side circuit unit are insulated by the transformer and the signal transmission element, and the detection circuit unit in the secondary side circuit unit and the switching control unit in the primary side circuit unit are used. Since it is configured to perform constant power control, the secondary side circuit unit is insulated from the primary side circuit unit connected to the power supply device, and the electric shock of the discharge lamp caused by the primary side power supply device can be eliminated. At the same time, the insulation distance can be reduced and the device can be downsized. Further, since the secondary side circuit unit detects power based on detection of both the lamp current and the lamp voltage and performs constant power control, finer power control can be performed at the end of the lamp life, for example.

  In the present invention, the secondary circuit portion is constituted by a main circuit and an auxiliary circuit, and the voltage converted by the first winding and the second winding from the start of the discharge lamp to the predetermined condition is supplied to the auxiliary circuit. Apply to the discharge lamp. Then, after satisfying the predetermined condition, the voltage converted by the first winding is applied to the discharge lamp by the main circuit, so that the converter can be reduced in size and efficiency.

  Further, in the present invention, the constant power control of the discharge lamp is performed by combining the self-excited flyback converter on the primary side and the detection circuit unit for detecting the power deviation on the secondary side. It is possible to reduce the influence of the ambient temperature of the lighting device and the individual differences of the members. Further, the output power error can be reduced by detecting the power deviation on the secondary side. Furthermore, it is possible to suppress the influence of residual AC ripple that causes flicker in a projector using a discharge lamp. Furthermore, since the discharge lamp lighting device can be configured with a single converter, it is possible to reduce the size of the device and improve the power efficiency.

  In the present invention, the discharge lamp lighting device turns off the switch when the amount of electricity related to the discharge lamp exceeds a predetermined value within the predetermined time from the start of starting the discharge lamp. Thereafter, after the switch is turned off, the switch is turned on again when the amount of electricity related to the discharge lamp exceeds a value different from the predetermined value. As described above, since the on / off control of the switch is performed based on the electric amount and time of the discharge lamp, the amount of current flowing through the FET or the like can be reduced, and further miniaturization can be achieved. In addition, since the amount of electricity is monitored again after the switch is turned off, even if the discharge lamp is extinguished due to a special arc after switching to the main circuit, the voltage is again supplied to the auxiliary circuit and more reliable. The present invention has an excellent effect, for example, that it is possible to increase the resistance.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are circuit diagrams showing the configuration of a discharge lamp lighting device according to the present invention. In FIG. 1, reference numeral 1 denotes a discharge lamp lighting device. The discharge lamp lighting device 1 is a primary arranged on the AC power supply 2 side with a transformer (hereinafter referred to as a transformer) 6 and a photocoupler 5 as a signal transmission element as a boundary. The side circuit unit 10 and the secondary circuit unit 20 disposed on the lamp 4 side are included. As described above, the secondary side circuit unit 20 is insulated from the primary side circuit unit 10 by the transformer 6 and the photocoupler 5. In this embodiment, an example is shown in which the present invention is applied to a discharge lamp lighting device that lights a discharge lamp such as a metal halide lamp used in a liquid crystal projector or the like.

  The primary side circuit unit 10 is connected to an AC power source 2 via a line filter 11, a bridge circuit 12 for smoothing and smoothing the AC from the AC power source 2, a smoothing capacitor 14, and an FET (Field Effect). Transistor) or a bipolar transistor and a power switch element 16, a switching control unit 13 for controlling the power switch element 16, and a starting resistor 15 connected thereto.

  A smoothing capacitor 14 is connected in parallel to the bridge circuit 12, and one end of the smoothing capacitor 14 is connected to the starting resistor 15 and the a terminal (positive electrode) of the primary coil (primary winding) 61 of the transformer 6. Yes. The other side of the starting resistor 15 is connected to the switching control unit 13. The transformer 6 includes a primary coil 61 having one end connected to the power switch element 16, a secondary coil (secondary winding) 62 including a first winding 621 and a second winding 622, and a switching control unit. 13 is provided with a feedback coil 63 connected to 13.

  The b terminal (negative electrode) of the primary coil 61 is connected to the drain of the power switch element 16. The source of the power switch element 16 is connected to the bridge circuit 12 and the gate is connected to the switching control unit 13, and the drain-source is turned on / off according to the gate control signal of the switching control unit 13. The f terminal (negative electrode) of the feedback coil 63 of the transformer 6 is connected to the source of the power switch element 16, the bridge circuit 12, and the switching control unit 13, and the e terminal (positive electrode) of the feedback coil 63 is also connected to the switching control unit 13. It is connected. The switching control unit 13 is also connected to the photocoupler 5 that transmits a control signal from the secondary side circuit unit 20.

  Next, the operation of the primary side circuit unit 10 will be described. A switch of the entire system (not shown) is inserted in series in, for example, a connection line between the AC power supply 2 and the line filter 11. When the system switch is off, power from the AC power source 2 is not supplied to the discharge lamp lighting device 1. Therefore, the switching control unit 13 does not operate, and the gate voltage Vgs of the power switch element 16 is 0 V, which is in an off state. When the system switch is turned on and power is supplied from the AC power supply 2, the AC voltage is rectified and smoothed by the bridge circuit 12 and the smoothing capacitor 14. Thereafter, the voltage of the line 151 rises, and power is supplied to the switching control unit 13 via the starting resistor 15 to start the operation, and the gate voltage is also applied to the power switch element 16. When the gate voltage Vgs of the power switch element 16 becomes equal to or higher than a predetermined voltage, the power switch element 16 is turned on.

  When the power switch element 16 is turned on, a current flows through the primary coil 61 due to the inductance of the primary coil 61 and the voltage applied to both ends ab. A voltage corresponding to the turn ratio is generated in the secondary coil 62 and the feedback coil 63. The a terminal of the primary coil 61, the e terminal of the feedback coil 63, the d terminal of the first winding 621 of the secondary coil 62, and the c terminal of the second winding 622 of the secondary coil 62 have the same polarity. (Positive electrode), and the generated voltages have the same polarity. The positive electrode (e terminal) of the feedback coil 63 is connected to the gate of the power switch element 16 via the switching control unit 13. That is, when the power switch element 16 is on, it is connected to the polarity side of the feedback coil 63 that maintains the on state.

  FIG. 3 is a circuit diagram showing a circuit configuration of the switching control unit 13. The switching control unit 13 includes a switch element 131, capacitors 132 and 137, resistors 133, 135 and 136, and a diode 134. In the figure, reference numeral 5 denotes a light receiving portion of the photocoupler. The gate of the power switch element 16 operates by applying a voltage generated in the feedback coil 63 via the resistor 136 and the capacitor 137. Once the power switch element 16 is turned on by the starting resistor 15, a positive voltage is generated at the e terminal of the feedback coil 63, so that the operation of the power switch element 16 continues to be turned on. The gate of the power switch element 16 is controlled by the switch element 131.

  The on / off operation of the switch element 131 is controlled by the voltage across the capacitor 132. The voltage of the capacitor 132 is controlled by the current flowing through the resistor 133 by the voltage generated at the e terminal of the feedback coil 63. That is, a positive voltage is generated at the e terminal of the feedback coil 63 and the power switch element 16 is turned on. However, the charge is charged to the capacitor 132 via the resistor 133, so that the switch element 131 is changed from OFF to ON. The gate of the power switch element 16 becomes the same potential as the drain and is turned off. The time during which the power switch element 16 is on is determined by the time constant of the resistor 133 and the capacitor 132. The constant is adjusted so that the desired power can be extracted. The capacitor 132 is also charged by the diode 134, the resistor 135, and the photocoupler 5. When the photocoupler 5 is frequently turned on, the capacitor 132 is quickly charged, and the time for the switch element 131 to change from on to off is shortened. The photocoupler 5 is controlled from a secondary side circuit unit 20 described later.

  Subsequently, an operation until the switch shifts from OFF to ON will be described. At the moment when the power switch element 16 is turned off, a positive voltage is generated at the c terminal and the g terminal of the secondary coil 62. The electric power stored in the transformer 6 while the power switch element 16 is on is output via the rectifier diode 22 and the rectifier diode 72 of the secondary side circuit unit 20. When the electric power stored in the transformer 6 becomes zero during the ON period, the remaining electric power generates a positive voltage at the e terminal of the feedback coil 63, so that the switch is turned ON again. The switching control unit 13 repeatedly performs the above on / off control. As described above, in the configuration including the smoothing capacitor 14, the transformer 6, the power switch element 16, the rectifier diode 22, the rectifier diode 72, the capacitor 23, and the capacitor 73 (see FIG. 2), power is supplied during the ON period of the power switch element 16. Is stored in the transformer 6 and is taken out to the secondary side during the off period. By controlling the on and off times, the output voltage is boosted or lowered with respect to the input voltage.

  Next, the configuration of the secondary circuit unit 20 will be described with reference to FIG. The secondary coil 62 is formed by a first winding 621 and a second winding 622 that share one terminal (c terminal) of the winding, and the turns ratio of the first winding 621 and the second winding 622 is as follows. For example, 13:12. The other end (d terminal) of the first winding 621 is grounded, and one end (c terminal) of the first winding 621, in other words, the other end (c terminal) of the second winding 622 is connected to the rectifier diode 22. Connected to the anode.

  One end (g terminal) of the second winding 622 is connected to the anode of the rectifier diode 72. A capacitor 73 connected in parallel to the lamp 4 is connected to the cathode of the rectifier diode 72 connected in series to the lamp 4. A switch 74 is connected to the cathode of the rectifier diode 72 and the capacitor 73.

  One of the switches 74 is connected to the anode of the diode 75 and the other is connected to the resistor 33 of the igniter 3. The igniter 3 includes a Sidac (registered trademark) 31 whose on / off control is switched by an applied voltage, a pulse transformer 32 to which one side of the Sidac 31 is connected, a resistor 33 and a capacitor 34 that determine the oscillation frequency of the Sidac 31, The diode 30 is connected in series to the lamp 4 and prevents a high voltage generated by the pulse transformer 32 from returning to the converter side. The cathode of the diode 75 is connected to 4 terminals of the 3-4 terminal of the pulse transformer 32.

Similarly to the cathode of the diode 75, the cathode of the diode 30 is connected to 4 terminals of the 3-4 terminal of the pulse transformer 32. On the other hand, one end of the Sidac 31 is connected to two terminals 1-2 of the pulse transformer 32, and the other end is connected between a resistor 33 and a capacitor 34 connected in series. One end of the first winding 621 (c terminal, the other end of the second winding 622) is connected to the anode of the rectifier diode 22. The cathode of the rectifier diode 22 connected in series to the lamp 4 is connected to the capacitor 23 connected in parallel to the lamp 4 and the anode of the diode 30. The voltage supplied via the rectifier diode 22 is smoothed by the secondary capacitor 23, and the smoothed voltage is applied to the lamp 4. The d terminal of the secondary coil 62 is grounded.
The diode 30 is the output of the main converter 70 (main circuit), and the diode 75 is the output of the auxiliary converter 71 (auxiliary circuit). The cathodes are connected to each other and connected to the lamp 4 via the 3-4 terminal which is the secondary side of the pulse transformer 32. The igniter 3 operates only when the lamp 4 is started, and thereafter acts as a choke coil. Since a high voltage of several kilovolts is generated while the igniter 3 is in operation, it is necessary to prevent the voltage from being transmitted to other circuits. However, the diode 30 and the diode 75 have a high voltage rating specification. . That is, the diode 30 and the diode 75 have both functions of preventing a high voltage at startup and switching the outputs of the main converter 70 and the auxiliary converter 71.

The first voltage dividing resistor 24 and the second voltage dividing resistor 25 are connected in parallel to the lamp 4, and the detected lamp voltage is output to the control unit 21. The current detection resistor 26 is connected in series with the lamp 4, and the detected lamp voltage is output to the control unit 21. The igniter 3 applies a high voltage of several kiloV to several tens of kiloV to the lamp 4 to start the lamp 4. After the arc discharge is maintained and the lamp 4 shifts to the steady state, the constant power control of the lamp 4 is performed by the detection circuit unit 22E of the control unit 21 and the switching control unit 13. The constant voltage control unit 23V controls the power switch element 16 via the photocoupler 5 and the switching control unit 13 so that the voltage across the capacitor 23 does not exceed a predetermined value when the lamp 4 is turned off. The constant current control unit 24 </ b> A controls the power switch element 16 through the photocoupler 5 and the switching control unit 13 so that a current greater than a predetermined value does not flow through the lamp 4 when the lamp 4 is lit.

  The operation from the start of lighting of the lamp 4 to glow discharge will be described. When the switch of the entire system (not shown) is off, no current flows through either the diode 30 or the diode 75. When the system switch is turned on, the power switch element 16 performs a switching operation as described above, whereby electric power is transmitted to the secondary side circuit unit 20 and the voltages of the capacitor 23 and the capacitor 73 rise. The winding ratio of the first winding 621 and the second winding 622 is 13:12, and the voltage of the capacitor 23 at no load is set to 130V by the first voltage dividing resistor 24 and the second voltage dividing resistor 25. When the voltage is detected and controlled by the constant voltage control unit 23V, the voltage of the capacitor 23 is 130V and the voltage of the capacitor 73 is 250V. The switch 74 is in an ON state, and the capacitor 34 is first charged through the switch 74 and the resistor 33 by the voltage 250 V of the capacitor 73. The charging time τ (time constant) is determined by τ = R × C. Note that. R is the resistance value of the resistor 33, and C is the capacitance of the capacitor 34.

  The on-voltage of the Sidac 31 is 220V, and when the voltage of the capacitor 34 reaches 220V, the Sidac 31 becomes conductive and 220V is applied to the 1-2 terminal of the pulse transformer 32. The ratio of the winding between the 1-2 terminals and the winding between the 3-4 terminals of the pulse transformer 32 is 1:25, a voltage of 5 kiloV is generated between the 3-4 terminals, and the lamp 4 starts operating. . In this case, since the voltage of the capacitor 73 is higher than the voltage of the capacitor 23, the diode 75 is turned on and the diode 30 is turned off, and a current is supplied to the lamp 4 mainly via the diode 75. That is, power is supplied through the rectifier diode 72, the capacitor 73, and the diode 75. After the dielectric breakdown, the lamp 4 shifts to glow discharge, and a voltage of 100 V to 200 V and a power of about 50 W are supplied via the diode 75. Except for the case where the lamp 4 is turned on and then goes off, 220 V, which is a voltage necessary for turning on the Sidak 31, is not charged in the capacitor 34, so the igniter 3 stops the high voltage generation operation.

  The switch 74 is composed of, for example, an FET or the like. The switch 74 is turned off or hot restarted due to transient instability at the start of the lamp 4 after the main switch is turned on (restarting from a state where the lamp 4 is hot). Switch on from off after 6 seconds. In FIG. 2, the switch 74 is in a position where the resistor 33 and the diode 75 are separated from the capacitor 73, but only the diode 75 may be separated from the capacitor 73. In this case, the resistor 33 is always supplied with current from the capacitor 73, but the voltage across the capacitor 73 when the lamp is lit is determined by the lamp voltage VL and the winding ratio of the first winding 621 and the second winding 622. Since this voltage is 220 V or less, the Sidac 31 does not operate. Therefore, the current flowing through the resistor 33 stops flowing when the capacitor 34 is charged, so that the switch 74 does not need to disconnect the resistor 33 and the capacitor 73. Further, in order to separate the diode 75 from the capacitor 73, a switch may be inserted on the anode side of the switch 74, or may be inserted on the cathode side. By disconnecting the diode 75 from the four terminals of the diode 30 and the pulse transformer 32, a path through which a current flows may be cut. Further, the switch 74 may be switched from on to off after a predetermined time has elapsed, or may be switched from on to off by detecting changes in lamp current and lamp voltage. In this case, the lamp current or lamp voltage information input to the control unit 21 is also input to the switch 74.

  The switch 74 has a CPU 741 to be described later, determines whether or not the lamp voltage VL (the voltage of the capacitor 23) is 100 V or less, and when the lamp voltage VL is 100 V or less, the glow discharge ends and the process proceeds to arc discharge. The switch 74 is turned off. Thereby, the power supply through the diode 75 is stopped. At this time, the lamp voltage VL is 100 V or less, and power supply by the main converter 70 through the rectifier diode 22, the capacitor 23, and the diode 30 is started. When the determination is made using the lamp current AL, the CPU 741 determines whether or not the lamp current AL is 1 A or more, and turns off the switch 74 when the lamp current AL becomes 1 A or more. Thereby, the power supply by the main converter 70 through the rectifier diode 22, the capacitor 23, and the diode 30 is started, and the power supply through the diode 75 is stopped.

  FIG. 4 is a graph showing the output characteristics of the discharge lamp lighting device 1. The vertical axis indicates the lamp voltage of the lamp 4, the unit is [V (volt)], the horizontal axis indicates the lamp current of the lamp 4, and the unit is [A (ampere)]. The transformer 6, power switch element 16, smoothing capacitor 14, rectifier diode 22, and capacitor 23 constitute a main converter 70. Main converter 70 is a self-excited flyback converter (RCC: Ringing Choke Converter). The characteristic indicated by the solid line in FIG. 4 is the characteristic of the main converter 70. On the other hand, the transformer 6, the power switch element 16, the smoothing capacitor 14, the rectifier diode 72, and the capacitor 73 constitute an auxiliary converter 71. The auxiliary converter 71 is also a self-excited flyback system. In the graph of FIG. 4, the solid line indicates the characteristics of the current / voltage supplied from the main converter 70. In the characteristic of the solid line, the characteristic of 130V constant at about 1.6 A or less is the characteristic of the constant voltage control unit 23V. The constant characteristic of 5A at about 40 V or less is the characteristic of the constant current control unit 24A. A hyperbola is a constant power characteristic of the detection circuit unit 22E. A dotted line is a characteristic of current and voltage supplied from the auxiliary converter 71. The open circuit voltage (the voltage at which the output current is zero), or the light load voltage with a small output current is 250 V, which is controlled by the first voltage dividing resistor 24 and the second voltage dividing resistor 25, and the first winding. The voltage is determined by the ratio between 621 and the second winding 622. The current drooping characteristic of 1 A is a result of being controlled by the current detection resistor 26.

  In the present embodiment, it is assumed that the rated power of the lamp 4 is 200 W, and that the lamp voltage VL is 120 V at the end of the life of the lamp 4. The open voltage generated in the capacitor 23 is 130 V so that 120 V can be driven, and the open voltage of the capacitor 73 is 250 V. After starting the lamp 4, the auxiliary converter 71 operates the igniter 3 to cause dielectric breakdown in the lamp 4 and then shift the lamp 4 to glow discharge.

  In the main converter 70 and the auxiliary converter 71, the primary side circuit unit 10 is common, and the rectifier diode 22 and the capacitor 23 of the secondary side circuit unit 20 and the like are individually provided. The transformer 6 is also common and has a secondary coil 62 for each. A converter that converts voltage, current, or power into a desired value generally determines the size, withstand voltage specification, and maximum current specification of components to be used depending on the input voltage range, output voltage range, output current range, and the like. The wider the input / output range described above, the generally required withstand voltage and maximum current rating become larger, the cost of parts becomes higher, and the outer shape tends to become larger.

  Since the withstand voltage is increased, there is a trade-off relationship in which the parasitic capacitance increases and the switching speed specification decreases. By reducing the output voltage of the main converter 70 from 250V to 130V, such an increase in the rating or size of the parts is avoided. As shown in FIG. 2, the control unit 21 detects and controls the voltage across the capacitor 23 with the first voltage dividing resistor 24 and the second voltage dividing resistor 25. That is, auxiliary converter 71 is equivalent to no control with respect to its output voltage. However, the auxiliary converter 71 outputs a voltage of 250 V required for dielectric breakdown, a current of 0.5 A at 100 V to 200 V required for glow discharge, or 50 W required to shift from glow discharge to arc discharge. It is about power. These operations are completed within a few seconds when lighting. Therefore, by controlling the main converter 70, the voltage determined by the turn ratio of the first winding 621 and the second winding 622 is extracted from the output of the auxiliary converter 71 and supplied to the lamp 4. Complete. The main converter 70 can be reduced in size by supplying voltage and power necessary for a short time when the lamp 4 is lit by the auxiliary converter 71 that is simply configured and easily controlled. Since the auxiliary converter 71 need not be controlled, the photocoupler 5 or the switching control unit 13 can be shared with the main converter 70.

In addition, when the auxiliary converter 71 is operated for 6 seconds from the start of lighting as described later, a constant current output of about 15V1A may be output from the auxiliary converter 71. This control is detected by the current detection resistor 26 and fixed. What is necessary is just to perform by the current control part 24A. Since the diode 75 is on and the diode 30 is off while the switch 74 is on, the constant current control unit 24A can perform control.
Even during the glow discharge period, the power switch element 16 performs an on-off operation, and the output voltage of the auxiliary converter 71 is not directly controlled, but the primary circuit unit 10 is in a period during which the switch 74 is on. Is supplied to the lamp 4 and is output to the lamp 4. Compared with a method in which a large-capacity electrolytic capacitor is provided in the secondary circuit unit 20 and power necessary for glow discharge is taken out by the electric charge charged in the capacitor, it is easy to reduce the size.

  FIG. 5 is a graph in which the operating point of the lamp 4 is schematically superimposed on the graph of FIG. The points indicated by arrows and (1) to (8) represent the operating points of the lamp 4 in time series. Before the lamp 4 is turned on (that is, before the discharge lamp lighting device 1 is operated), the current is 0 (zero) A, and the voltage is 0 (zero) V determined by the output state of the RCC converter. When the discharge lamp lighting device 1 starts operating, the auxiliary converter 71 operates and 250 V is generated at both ends of the capacitor 73. In response to this voltage, the igniter 3 operates. A high voltage of several kV to several tens of kV is generated in the lamp 4 and applied to the lamp 4. In the lamp 4, dielectric breakdown occurs due to high pressure, and current starts to flow.

  The initial lighting state of the lamp 4 lights in a mode called glow discharge. As shown in FIG. 5, the lamp voltage at that time is about 100V to 200V, and the lamp current is about 0.5A. When sufficient power is supplied to the lamp 4, the glow discharge shifts to the initial arc discharge. In this way, the auxiliary converter 71 supplies the power necessary for the glow discharge in (1) to (3) and the initial arc discharge in (4). At this time, the characteristic of the lamp 4 is in a state called negative resistance, and a current flows without limit. In this case, as described above, the constant current control for setting the upper limit current to 1 A is performed by the constant current control unit 24A or another constant current control unit (not shown).

  When the constant current control unit 24A limits the current of the output of the auxiliary converter 71 and the output of the main converter 70, the circuit for limiting the first upper limit current (1A in this example) for the auxiliary converter 71 and the main converter 70 A circuit for limiting the second upper limit current (5A in this example) is provided, and the circuit for performing the first upper limit current limit is switched from the circuit for performing the first upper limit current limit after the elapse of a predetermined time after the start of lighting. Also good. Alternatively, a circuit for limiting the first upper limit current (1 A in this example) may be provided for the auxiliary converter 71 separately from the constant current control unit 24A. In the present embodiment, the first upper limit current is 1 A, but the present invention is not limited to this, and may be 2 A, for example. Depending on the type of the lamp 4, there is a case where the current flowing for a few seconds from the start is limited, so that the blackening of the lamp can be avoided and the service life can be extended. Thereafter, the 5 A current switching becomes effective.

  Six seconds after the start of lighting of the lamp 4, the switch 74 is turned off, the power supply is switched from the auxiliary converter 71 to the main converter 70, and the state of the lamp 4 shifts from (4) to (5). During the initial arc lighting, the lamp 4 generates heat and the lamp voltage rises ((5) to (7)). The discharge lamp lighting device 1 detects the fluctuation of the lamp voltage and shifts from the constant current to the constant power control by the detection circuit unit 22E. In the constant power control, the current flowing as the lamp voltage increases is decreased, and the lamp 4 is stably lit at the stage of steady lighting (7), which is in a state of thermal equilibrium. At the end of the life, for example, the lamp voltage rises to 120 V as indicated by (8), but the detection circuit unit 22E performs control to reduce the current and keep the power constant.

  FIG. 6 is a graph in which the operating point of the lamp 4 is schematically superimposed on the graph of FIG. 4 when the switch 74 is adaptively controlled by monitoring the lamp voltage VL. FIG. 5 shows a transition in the case where the switch 74 is turned off after a predetermined time has elapsed since the start of lighting of the lamp 4, but FIG. 6 shows that the switch 74 is turned off when the lamp voltage becomes 100V or less. It is a graph at the time of switching electric power supply from the converter 71 to the main converter 70. After the glow discharge starts, the voltage gradually decreases and shifts to (1) to (3). In the stage (3), since the lamp voltage VL is 100 V or less, the switch 74 is turned off and power is supplied by the main converter 70. In this case, the lamp 4 proceeds to (4), and constant current control is performed by the constant current control unit 24A. In this case, as compared with the case where the switch 74 is turned off after a predetermined time has elapsed, the current limiting unit for the auxiliary converter 71 is not necessary, and the circuit scale is reduced. Further, since the maximum output current of the auxiliary converter 71 is suppressed to about 0.5 A, the current rating of the components can be lowered. The time when the lamp voltage is 100 V or less after the start of the lamp 4 is a short period of, for example, several tens of milliseconds. Compared to the case where the lamp is continuously operated for 6 seconds, the heat dissipation design of the loss generated by the circuit is easier. Yes. Depending on the type of the lamp 4, there is a lamp whose life can be extended by supplying a large amount of power at the time of start-up and promptly shifting to a steady lighting state. By supplying a large current of 5 A to such a lamp 4 immediately after the glow discharge is completed, it is possible to extend the life.

  In order to reduce the rush current at start-up and to control the stable lighting of the lamp 4 at start-up, the capacitor is connected with a switch such as an FET so that the capacity of the smoothing capacitor located at the output of the converter is reduced at start-up. In this embodiment, for example, if the capacitor 73 of the auxiliary converter 71 is 0.1 uF (microfarad) and the capacitor 23 of the main converter 70 is 2 uF, the FET for switching the capacitor is switched. 74 can be substituted. That is, the capacity of the capacitor 73 may be determined according to the startup of the lamp 4.

  Thereafter, the lamp voltage increases ((4) to (6)). The discharge lamp lighting device 1 detects the fluctuation of the lamp voltage and shifts from the constant current to the constant power control by the detection circuit unit 22E. In constant power control, the current that flows as the lamp voltage increases is decreased, and stable rated lighting is performed at the stage of rating (6). At the end of the life, for example, the lamp voltage rises to 120 V as indicated by (7), but control to reduce the current is performed by the detection circuit unit 22E.

  The switch 74 may be turned on / off by combining control using a timer and control by monitoring the lamp voltage or lamp current. FIG. 7 is a circuit diagram showing a circuit configuration of the switch 74. The switch 74 includes an FET 747, a resistor 748, a diode 751, a transistor 749, a diode 750, an insulating transformer 745, a capacitor 746, a CPU (Central Processing Unit) 741, a timer 743, and a RAM (Random Access Memory) 742.

  The CPU 741 is connected to a timer 743 that outputs time information, a RAM 742 that stores various calculation results and a program for executing on / off control of the FET 747, and a terminal 1 of the isolation transformer 745. The CPU 741 receives a start signal indicating the start of the lamp 4 accompanying the start of the entire system, and information on the lamp current and the lamp voltage of the lamp 4. The CPU 741 outputs a high signal or a low signal to the terminal 1 on the primary side of the isolation transformer 745 according to the program stored in the RAM 742 based on the start signal, the time information from the timer 743, the lamp voltage or the lamp current.

  A terminal 2 on the primary side of the insulation transformer 745 is connected to the ground via a capacitor 746. The secondary side terminal 4 of the isolation transformer 745 is connected to the anode side of the diode 751 and the base of the pnp type transistor 749. The secondary terminal 3 of the isolation transformer 745 is connected to the cathode of the diode 750 connected to the collector of the transistor 749 on the anode side, one end of the resistor 748 and the source of the FET.

  The FET 747 is turned on when a high signal is output from the CPU 741 and turned off when a low signal is output. The gate of the FET 747 is connected to the other end of the resistor 748, the cathode of the diode 751, and the collector of the transistor 749.

  Next, the operation of the switch 74 will be described. When a high signal is input to the terminal 1 of the insulating transformer 745, a positive potential is generated at the terminal 4 with respect to the terminal 3. As a result, the diode 751 becomes conductive and the transistor 749 is turned off. The FET 747 is turned on when a positive potential is applied to the gate with respect to the source. As a result, conduction between the drain and source flows, and current flows from the input to the output. On the other hand, when a low signal is input to the terminal 1 of the insulating transformer 745, the terminal 4 is negative with respect to the terminal 3. In this case, a bias voltage is applied between the emitter and base of the transistor 749 to turn it on. A reverse voltage is applied to the diode 751 and the diode 751 is turned off. As a result, the charge charged in the capacitance present at the gate of the FET 747 is extracted via the transistor 749-diode 750, and the FET 747 is turned off. The insulation transformer 745 level-shifts the 5V output of the CPU 741 to a high voltage.

  FIG. 8 is a flowchart showing the procedure of control processing by the CPU 741. A switch of the entire system (not shown) is operated, and a start signal indicating the start of the lamp 4 is input to the CPU 741 (step S81). The CPU 81 starts timing by the timer 743 using the input of the start signal as a trigger (step S82). Time information is output from the timer 743 to the CPU 741. Similar to this processing, the CPU 741 outputs a high signal to the terminal 1 of the isolation transformer 745 (step S83). As a result, the switch 74 is turned on, and power is supplied by the auxiliary converter 71.

  Based on the input lamp voltage or lamp current (electric quantity), the CPU 741 determines whether the input lamp voltage is lower than a predetermined voltage or whether the input lamp current is higher than a predetermined current (step). S84). The predetermined voltage is, for example, 100 V, and the predetermined current is 1 A. These pieces of information are stored in the RAM 742, respectively. When the CPU 741 determines that the input lamp voltage is equal to or lower than the predetermined voltage or the input lamp current is equal to or higher than the predetermined current (YES in step S84), the CPU 741 determines that the process has shifted to arc discharge, and transmits the low signal to the isolation transformer 745. To the terminal 1 (step S87). As a result, the switch 74 is turned off, and power is supplied by the main converter 70.

  The CPU 741 refers to the time information output from the timer 743 and determines whether or not a predetermined time has elapsed (step S88). The predetermined time is stored in the RAM 742 as 6 seconds, for example. If the CPU 741 determines that the predetermined time has elapsed (YES in step S88), the CPU 741 determines that the lamp 4 is normally lit and ends the process. On the other hand, when the CPU 741 determines that the predetermined time has not elapsed (NO in step S88), the CPU 741 determines whether the input lamp voltage is equal to or higher than the auxiliary predetermined voltage based on the input lamp voltage or lamp current, or It is determined whether or not the input lamp current is equal to or less than the auxiliary predetermined current (step S89). The auxiliary predetermined voltage and the auxiliary predetermined current are for detecting the extinction due to the special arc after the initial arc. The auxiliary predetermined voltage and the auxiliary predetermined current are different from the above-described predetermined voltage and predetermined current. For example, the auxiliary predetermined voltage and the auxiliary predetermined current may be set to 120 V and the auxiliary predetermined current 0.1 A, and these pieces of information are stored in the RAM 742. .

  When the CPU 741 determines that the input lamp voltage is not equal to or higher than the auxiliary predetermined voltage or the input lamp current is not equal to or lower than the predetermined current (NO in step S89), the CPU 741 determines that no extinction has occurred, and step S88 is performed again. Migrate to On the other hand, when the lamp 4 is extinguished, the lamp 4 is in an insulated state, the lamp current becomes 0 A, and the lamp voltage becomes indefinite, so the low voltage control is activated and becomes 130V. Therefore, when the CPU 741 determines that the input lamp voltage is equal to or higher than the auxiliary predetermined voltage or the input lamp current is equal to or lower than the predetermined current (YES in step S89), it determines that the extinction has occurred and isolates the high signal. Output to the terminal 1 of the transformer 745 (step S810). As a result, the switch 74 is turned on again, and power is supplied by the auxiliary converter 71. Thereafter, the CPU 741 proceeds to step S84 and repeats the above processing.

  In step S84, if the CPU 741 determines that the input lamp voltage is equal to or lower than the predetermined voltage or the input lamp current is not equal to or higher than the predetermined current (NO in step S84), it is determined whether or not a predetermined time has elapsed (step S84). Step S85). If the CPU 741 determines that the predetermined time has not elapsed (NO in step S85), the process proceeds to step S83 to continue monitoring. On the other hand, if the CPU 741 determines that the predetermined time has elapsed (YES in step S85), it outputs a low signal to the terminal 1 of the pulse transformer 745 (step S86). As a result, the switch 74 is turned off, and power is supplied by the main converter 70.

  FIG. 9 is a block diagram showing a circuit configuration of the detection circuit unit 22E. The detection circuit unit 22E is a circuit that compares the lamp power obtained from the lamp voltage and the lamp current with a predetermined target power (200 W in this embodiment), and outputs the deviation to the photocoupler 5. For example, the microcomputer shown in FIG. A built-in detection circuit unit 22E is used. The detection circuit unit 22E includes a voltage detection non-inverting amplifier 221, a current detection non-inverting amplifier 222, A / D (analog-digital) converters 223, 224, a microcomputer 225, and a D / A (digital-analog) converter 226. It is comprised including.

  The voltage detecting non-inverting amplifier 221 is connected to the first voltage dividing resistor 24 and the second voltage dividing resistor 25 for detecting the lamp voltage, and is divided by the first voltage dividing resistor 24 and the second voltage dividing resistor 25. The lamp voltage is amplified at a predetermined amplification factor. The amplified ramp voltage is digitized by the A / D converter 223 connected to the output terminal of the voltage detection non-inverting amplifier 221 and input to the microcomputer 225.

  The current detection non-inverting amplifier 222 is connected to a lamp current detection current detection resistor 26 (for example, a high-precision 50 mΩ resistor), and amplifies the voltage converted by the current detection resistor 26 at a predetermined amplification factor. To do. The voltage applied to the amplified lamp current is digitized by the A / D converter 224 connected to the output terminal of the current detection non-inverting amplifier 222 and input to the microcomputer 225. The microcomputer 225 includes a processor and a memory (not shown) and stores a predetermined target power Pexp as a target. The processor of the microcomputer 225 calculates the lamp power Pdet by multiplying the values relating to the lamp voltage and the lamp current output from the A / D converters 223 and 224.

  The processor of the microcomputer 225 calculates a deviation between the target power Pexp read from the memory and the calculated lamp power Pdet, and a D / A conversion connected to the output side of the microcomputer 225 by an operation signal obtained by multiplying this by a negative gain. To the device 226. The D / A converter 226 converts the operation signal into an analog signal and outputs it to the photocoupler 5.

  As shown in FIGS. 1 and 2, the photocoupler 5 that secures insulation between the primary side circuit unit 10 and the secondary side circuit unit 20 is connected to the switching control unit 13 and switches the operation signal corresponding to the deviation. Transmit to the control unit 13. When the lamp power Pdet is larger than the target power Pexp, that is, when the deviation is positive, a negative operation signal is output from the photocoupler 5, and the switching control unit 13 receives this and the power supplied to the lamp 4 decreases. The primary side circuit unit 10 is controlled. On the other hand, when the lamp power Pdet is smaller than the target power Pexp, that is, when the deviation is negative, a positive operation signal is output from the photocoupler 5, and the switching control unit 13 receives this and the power supplied to the lamp 4 is The primary side circuit unit 10 is controlled to increase. When the deviation becomes 0 by this feedback control, the responses of the detection circuit unit 22E and the switching control unit 13 are stopped, and the state is shifted to the steady state again.

  As described in FIG. 9, the detection circuit unit 22E is not limited to this configuration as long as it detects a deviation between the target power Pexp and the lamp power Pdet. For example, the detection circuit unit 22E may be realized using an analog multiplication circuit. good. FIG. 10 is a block diagram showing a circuit configuration of a detection circuit unit 22E using an analog multiplication circuit. The detection circuit unit 22E includes a voltage detection non-inverting amplifier 221, a current detection non-inverting amplifier 222, an analog multiplication circuit 227, a target power output circuit 228, and an error amplifier 229. The analog multiplication circuit 227 is connected to the output terminals of the voltage detection non-inverting amplifier 221 and the current detection non-inverting amplifier 222, and multiplies the output lamp current by the lamp voltage and gives an error to the multiplied lamp power Pdet. Input to the inverting input terminal of the amplifier 229.

  A target power output circuit 228 is connected to the non-inverting input terminal of the error amplifier 229. The error amplifier 229 compares the target power Pexp output from the target power output circuit 228 with the lamp power Pdet, and the error amplifier 229 sucks a current corresponding to the deviation from the output terminal. The output terminal of the error amplifier 229 is connected to the cathode side of a photodiode (not shown) of the photocoupler 5 and performs an on / off operation according to the current sucked by the output terminal, and sends a signal corresponding to the deviation to the switching control unit 13. Transmit to. The switching control unit 13 performs switching control according to the signal from the photocoupler 5 until the deviation becomes zero.

  FIG. 11 is a circuit diagram showing a circuit configuration of the constant current control unit 24A. The constant current control unit 24A includes a current detection resistor 26 for detecting lamp current, a shunt regulator 243, an oscillation prevention capacitor 245 for preventing oscillation, an oscillation prevention resistor 246, and a first resistor 241 connected in parallel to the photocoupler 5. A second resistor 242 connected in series is included. A constant voltage power supply of about 13 V is connected to one side of the second resistor 242. The secondary bus line in the figure refers to a part that passes the igniter 3 from the cathode side of the rectifier diode 22 to the upper side of the lamp 4 in FIG. 2 and supplies power to the lamp 4. is there. The lamp current flows from the secondary bus line through the lamp 4 from the top to the bottom in the figure, and then flows to the ground via the current detection resistor 26. The shunt regulator 243 compares the reference voltage Vref with the voltage Vr obtained by multiplying the lamp current by the resistance value of the current detection resistor 26 for detecting the lamp current. When Vref and Vr are equal, a current flows through the cathode and the photocoupler 5 operates. A signal is transmitted from the photocoupler 5 to the switching control unit 13 and constant current control is performed. As a result, the lamp current decreases. When the current limit value is 3 A and the reference voltage Vref of the shunt regulator 243 is 2.5 V, the resistance value of the current detection resistor 26 may be 820 mΩ.

  FIG. 12 is a circuit diagram showing another circuit configuration of the constant current control unit 24A. The constant current control unit 24A shown in FIG. 11 may be realized by the circuit configuration shown in FIG. As shown in FIG. 12, an operational amplifier 248 is inserted between the current detection resistor 26 and the reference voltage control terminal of the shunt regulator 243. The lamp current output from the current detection resistor 26 is input to the non-inverting input terminal of the operational amplifier 248, and an amplified signal is output from the output terminal of the operational amplifier 248 to the reference voltage control terminal of the shunt regulator 243. In the circuit configuration of FIG. 11, when a current of 3 A at maximum flows through the resistance value 820 mΩ of the current detection resistor 26, a large resistor (approximately 7 W) is required. When it is difficult to use such a large resistor, as shown in FIG. 12, the resistance value of the current detection resistor 26 may be 1/10 of 82 mΩ and amplified by the operational amplifier 248 (gain of 10 times).

  FIG. 13 is a circuit diagram showing a circuit configuration of the constant voltage controller 23V. The constant voltage control unit 23V includes a shunt regulator 243, an oscillation preventing capacitor 245 for preventing oscillation, an oscillation preventing resistor 246, a first resistor 241 connected in parallel to the photocoupler 5, and a second resistor 242 connected in series thereto. A third resistor 244 and a fourth resistor 231 are provided on the secondary bus line. A third resistor 244 is connected to the reference voltage control terminal of the shunt regulator 243. The voltage of the reference voltage control terminal of the shunt regulator 243 is Vr, and the reference voltage is Vref. When Vr <Vref, no current flows through the cathode. On the other hand, when Vr> Vref, a current flows to the cathode, the photocoupler 5 operates, and a signal is transmitted from the photocoupler 5 to the switching control unit 13. As a result, constant voltage control is performed and the secondary bus line is connected. The voltage drops and Vr becomes Vref or less. Note that the photocoupler 5 may share the one described in FIGS. 9 to 12, for example, by connecting the cathode side of the photodiode of the shared photocoupler to the cathode side of the shunt regulator of each circuit block. The above-described constant power control, constant voltage control, and constant current control operate with or logic.

  Since the secondary side circuit unit 20 is insulated from the primary side circuit unit 10 as described above, the safety of the secondary side circuit unit 20 and the downsizing of the discharge lamp lighting device 1 and the projector including the same are achieved. Can also be planned. Further, since the detection circuit unit 22E in the secondary side circuit unit 20 detects and controls the deviation between the target power and the power of the lamp 4, more detailed constant power control of the lamp 4 is possible. In addition, although the constant current control of FIG. 4 was shown with the straight line, it may not be a straight line. Furthermore, although the constant power control is indicated by a hyperbola, it may be realized by linear approximation.

  Although the switching control unit 13 has been described with respect to the form using the self-excited flyback system as shown in FIG. 3, it may be a separately excited flyback system. FIG. 14 is a circuit diagram showing a circuit configuration of the separately-excited flyback switching control unit 13. A control circuit 2S1 that controls the switching control unit 13 is connected to an auxiliary power source 2S different from the AC power source 2 via an input terminal Vcc, and receives power from the auxiliary power source 2S. A capacitor is connected to the FRQ terminal of the control circuit 2S1 to adjust the frequency.

  The phototransistor side of the photocoupler 5 is connected to the FB terminal of the control circuit 2S1, and the power switch element 16 connected via the CTL terminal is controlled by the magnitude of the current output from the photocoupler 5. That is, a PWM signal is output from the CTL terminal, and the gate of the power switch element 16 is turned on / off. While the pulse is on, the power switch element 16 is on.

  Also in the case of the separately excited flyback method, it is possible to efficiently extract the voltage for the igniter 3 and the glow discharge power by providing a dedicated winding in the secondary side circuit unit 20 and taking out a separate voltage. For both self-excited flyback and separately-excited flyback, the output stage coil is not required and the number of diodes for rectification is reduced compared to a forward type converter. Is possible. In FIG. 2, the first winding 621 (between d and c) and the second winding 622 (between c and g) share c. Here, for example, the second winding 622 may be provided between d and g, and the winding ratio between the first winding 621 and the second winding 622 may be 13:25.

  The case where the DC lamp 4 is driven has been described above. When the AC lamp 4 is driven, an inverter circuit (not shown) may be inserted before the igniter 3. The inverter circuit is usually composed of four FET switches. The polarity of the voltage applied to both ends of the lamp 4 is switched. Here, only a slight direct current component is applied to the AC lamp 4, which causes a major deterioration in life. In the present embodiment, it is necessary to perform power control and current control in the inverter circuit. Therefore, it is easy to avoid applying a direct current.

    The CPU 741 in FIG. 7 and the microcomputer 225 in FIG. 9 may be integrated and processed by a single device. In the above, the power or voltage required for the glow discharge, and the example of the VL for determining the glow discharge and the arc discharge are described numerically. However, the present application is not limited to this numerical value. For example, the rated power of the lamp 4 is as wide as 50W to 300W. Based on the embodiment, the apparatus may be adjusted according to the specifications of the lamp 4.

  As described above, in this embodiment, the lamp 4 can be ideally controlled with a simple configuration. By using a flyback converter capable of step-up / step-down, it is possible to drive the lamp 4 regardless of the type of the lamp 4 (discharge lamp) such as a xenon lamp, a metal halide lamp, or a high-pressure mercury lamp. The flyback converter may be self-excited or separately excited. By providing the transformer 6 of the flyback converter with a sub-winding, an auxiliary converter can be configured easily. It is possible to easily extract a high voltage with a common control switch. By taking out the voltage necessary for the igniter 3 and the power necessary for glow from the auxiliary converter 71, the main converter 70 responsible for arc discharge can be reduced in size. Can be achieved. Further, it is not necessary to add a large capacitor connected in parallel to the lamp 4. Since the main converter 70 and the auxiliary converter 71 each have two smoothing capacitors (capacitor 23 and capacitor 73), if the capacitor capacity of the auxiliary converter 71 is reduced, the lamp 4 will be stabilized at the time of lighting, and the occurrence frequency of extinction will be reduced. To do. Further, rush current can be prevented.

Embodiment 2
The discharge lamp lighting device 1 described above is applied to, for example, a projector. FIG. 15 is a block diagram showing a hardware configuration of the projector. The projector 300 includes a discharge lamp lighting device 1, a lamp 4, a reflecting mirror 321, a color wheel 320, an image forming element (hereinafter, DMD (Digital Micromirror Device (registered trademark)) 360, an image forming element control circuit 370 according to the first embodiment. , A projection lens 380, a fan 330, a main control unit 390, and a video signal processing unit 391.

  The main control unit 390 controls each hardware unit described above according to a program stored in a memory (not shown). The video signal is input to the video signal processing unit 391. The video signal processing unit 391 performs video signal processing such as synchronization separation and scaling, and outputs the processed video signal to the video forming element control circuit 370. In the projector 300, white light emitted from the lamp 4 is collected and applied to the color wheel 320. The color wheel 320 is configured as a disk in which red, blue and green optical filters are arranged in the circumferential direction, and is rotated at high speed by a drive motor (not shown).

  With the rotation of the color wheel 320, each color filter is sequentially inserted into the optical path of the light emitted from the lamp 4, and the white light irradiated to the color wheel 320 is converted into red, green and blue monochromatic lights. Color separation is performed by division. Each separated monochromatic light is sent to the reflecting mirror 321 and irradiated to the DMD 360. A liquid crystal panel may be used instead of the DMD. The DMD 360 is driven and controlled by the image forming element control circuit 370. The video forming element control circuit 370 drives the DMD 360 according to the input video signal. Specifically, each cell and minute mirror of the DMD 360 are turned on or off according to the input video signal to reflect the emitted monochromatic light in units of pixels and perform light modulation to form image light. The formed image light is incident on the projection lens 380 and enlarged and projected onto a screen or the like (not shown) by the projection lens 380.

  The discharge lamp lighting device 1 controls lighting and extinguishing of the lamp 4. The fan 330 is for cooling the inside of the lamp 4 or the projector 300, and is driven by a motor (not shown). In the present embodiment, the discharge lamp lighting device 1 has been described as being applied to the projector 300. However, the present invention is not limited to this and may be applied to general lighting or the like.

  The second embodiment is configured as described above, and the other configurations and operations are the same as those of the first embodiment. Therefore, corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.

It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on this invention. It is a circuit diagram which shows the structure of the discharge lamp lighting device which concerns on this invention. It is a circuit diagram which shows the circuit structure of a switching control part. It is a graph which shows the output characteristic of a discharge lamp lighting device. FIG. 5 is a graph in which the operating point of the lamp is schematically superimposed on the graph of FIG. 4. FIG. 5 is a graph in which lamp operating points are schematically superimposed on the graph of FIG. 4 when the lamp voltage VL is monitored and the switch is adaptively controlled. It is a circuit diagram which shows the circuit structure of a switch. It is a flowchart which shows the procedure of the control processing by CPU. It is a block diagram which shows the circuit structure of a detection circuit part. It is a block diagram which shows the circuit structure of the detection circuit part using an analog multiplication circuit. It is a circuit diagram which shows the circuit structure of a constant current control part. It is a circuit diagram which shows the other circuit structure of a constant current control part. It is a circuit diagram which shows the circuit structure of the constant voltage control part 23V. It is a circuit diagram which shows the circuit structure of the switching control part of a separately excited flyback system. It is a block diagram which shows the hardware constitutions of a projector. It is a circuit diagram which shows the structure of the conventional discharge lamp lighting device.

Explanation of symbols

1 Discharge lamp lighting device 2 AC power supply (power supply device)
3 Igniter 4 Lamp (Discharge lamp)
5 Photocoupler (signal transmission element)
6 Transformer 10 Primary side circuit unit 11 Line filter 13 Switching control unit 15 Start resistance 16 Power switch element 20 Secondary side circuit unit 21 Control unit 22 Rectifier diode 23 Capacitor 22E Detection circuit unit 23V Constant voltage control unit 24 First voltage division Resistor 24A Constant current control unit 25 Second voltage dividing resistor 26 Current detection resistor 30 Diode 61 Primary coil 62 Secondary coil 63 Feedback coil 70 Main converter 71 Auxiliary converter 72 Rectifier diode 73 Capacitor 74 Switch 75 Diode 300 Projector 621 First volume Wire 622 second winding

Claims (13)

In a discharge lamp lighting device for lighting a discharge lamp,
A primary circuit connected to the power supply;
A transformer connected to the primary circuit section for converting a voltage;
A secondary-side circuit unit connected to the transformer and applying a converted voltage to the discharge lamp;
A detection circuit unit provided in the secondary side circuit unit, which detects an output voltage and an output current of the discharge lamp to detect a deviation from a predetermined power;
A signal transmission element that is provided between the primary side circuit unit and the secondary side circuit unit and transmits a signal corresponding to the deviation detected by the detection circuit unit to the primary side circuit unit;
A switching control unit that is provided in the primary side circuit unit and performs switching control related to constant power lighting based on a signal transmitted from the signal transmission element;
The secondary winding of the transformer includes a first winding and a second winding,
The secondary side circuit section is
An auxiliary circuit for applying a voltage converted by the first winding and the second winding to the discharge lamp until a predetermined condition is satisfied after starting the discharge lamp;
The discharge lamp lighting device further comprising: a main circuit that applies the voltage converted by the first winding to the discharge lamp after satisfying the predetermined condition. The auxiliary circuit is
A diode connected to one end of the second winding;
A capacitor connected to the cathode of the diode and supplying a charged voltage to the discharge lamp;
The discharge lamp lighting device according to claim 1, further comprising: a switch connected to a cathode of the diode and the capacitor. The main circuit is:
A diode connected to the other end of the second winding and one end of the first winding having a common output end;
The discharge lamp lighting device according to claim 1, further comprising: a capacitor connected to a cathode of the diode and supplying a charged voltage to the discharge lamp. A diode connected to the output of the main circuit;
A diode connected to the output of the auxiliary circuit;
4. The discharge according to claim 1, wherein a cathode of a diode connected to the output of the main circuit and a cathode of a diode connected to the output of the auxiliary circuit are connected to each other. Electric light lighting device. The diode connected to the output of the main circuit and the diode connected to the output of the auxiliary circuit are rated specifications of a high withstand voltage for preventing a high voltage generated in an igniter. The discharge lamp lighting device described. The switch is turned on at the start of starting the discharge lamp, power is supplied from the auxiliary circuit to the discharge lamp, and the switch is turned off after the predetermined condition is satisfied. The discharge lamp lighting device according to any one of 5. The predetermined condition is that a predetermined time elapses;
The auxiliary circuit is
After the start of starting the discharge lamp, the voltage converted by the first winding and the second winding is applied to the discharge lamp until a predetermined time elapses.
The main circuit is:
The discharge lamp according to any one of claims 1 to 6, wherein a voltage converted by the first winding is applied to the discharge lamp after the predetermined time has elapsed. Lighting device. The predetermined condition is that the voltage of the capacitor of the main circuit is a predetermined voltage value or less,
The auxiliary circuit is
After the start of the discharge lamp, the voltage converted by the first winding and the second winding is applied to the discharge lamp until the voltage of the capacitor of the main circuit becomes a predetermined voltage value or less. Yes,
The main circuit is:
The voltage of the capacitor | condenser of the said main circuit becomes a predetermined voltage value or less, It is comprised so that the voltage converted by the said 1st winding may be applied to the said discharge lamp. The discharge lamp lighting device according to any one of the above. The predetermined condition is that a current related to the discharge lamp is equal to or greater than a predetermined current value,
The auxiliary circuit is
After starting the discharge lamp, the voltage converted by the first winding and the second winding is applied to the discharge lamp until the current related to the discharge lamp becomes equal to or higher than a predetermined current,
The main circuit is:
7. The device according to claim 1, wherein a voltage converted by the first winding is applied to the discharge lamp after a current related to the discharge lamp becomes equal to or greater than a predetermined current. 8. The discharge lamp lighting device according to one. Means for turning off the switch when the amount of electricity related to the discharge lamp exceeds a predetermined value within the predetermined time from the start of starting the discharge lamp;
The apparatus further comprises means for turning on the switch again when the amount of electricity related to the discharge lamp exceeds a value different from the predetermined value after the switch is turned off by the means. The discharge lamp lighting device according to 1.   The discharge lamp lighting device according to any one of claims 1 to 10, wherein the primary side circuit unit is a self-excited flyback converter.   The discharge lamp lighting device according to claim 1, wherein the signal transmission element is a photocoupler.   A projector comprising the discharge lamp lighting device according to any one of claims 1 to 12.

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