JP2002043077A - Discharge lamp lighting device and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device, capable of restricting lowering of the light output due to a rise of the lamp temperature and current leakage, and to provide a light source device. SOLUTION: This discharge lamp lighting device 8 is provided with a step-up transformer Tr1, having a primary coil Tr1a connected to a switching element Q1 at one end thereof and a secondary coil Tr1b connected to a discharge lamp EL. The voltage of the primary coil Tr1a of the step-up transformer Tr1 at the one end thereof is detected, and the switching operation of the switching element Q1 is controlled, so as to control the secondary output of the step-up transformer Tr1, in response to the voltage. With this structure, the lamp voltage of the secondary coil Tr1b is detected in a pseudo-operation manner, by detecting the voltage of the primary coil Tr1a so as to perform the feedback control, and the structure of the voltage detecting means is simplified, and the lowering of the lamp voltage with the current leak and a rise of the lamp temperature is detected, to restrain the lowering of the light output of the lamp EL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device and a light source device in which the operation of a discharge lamp having external electrodes is stabilized.

[0002]

2. Description of the Related Art Conventionally, as this type of discharge lamp lighting device, for example, a discharge lamp lighting device for a white or monochromatic fluorescent lamp of an external electrode xenon lamp used for a light source device of an image reading device such as a copying machine or an image scanner. Are known.

This discharge lamp lighting device uses a pulse lighting method instead of a sine wave lighting method in order to increase the illuminance of a fluorescent lamp, as described in, for example, Japanese Patent Application Laid-Open No. H11-307292. In addition, the switching element of the inverter circuit is controlled to convert the high frequency alternating current.

The above-described prior art discharge lamp lighting device detects a lamp current, and performs feedback control of a switching element of an inverter circuit based on the detected current to suppress fluctuations in lamp light output.

[0005]

By the way, in a discharge lamp lighting device, a current is supplied from a lead wire called a harness connecting the lamp and an inverter circuit or a lamp itself to a metal member such as a chassis or a reflector of the lighting device. May be leaked, and the light output of the lamp may be reduced because the inverter circuit controls the current on the secondary side of the step-up transformer. That is, since the conventional discharge lamp lighting device detects the current on the secondary side of the step-up transformer and also detects the leakage current that does not substantially contribute to the discharge, the reduction of the light output due to the leakage current is suppressed. Such feedback control cannot be performed.

On the other hand, the decrease in the light output due to the increase in the lamp temperature is caused by the fact that the lamp current is controlled by the conventional discharge lamp lighting device, and the lamp impedance decreases with the increase in the lamp temperature. This is because the power is reduced.

In order to suppress a decrease in light output due to a rise in lamp temperature, it may be better to perform feedback control by detecting the lamp voltage. However, since the lamp voltage on the secondary side of the step-up transformer is high, In addition, high withstand voltage characteristics are required for the elements used in the voltage detection circuit, and the degree of freedom of the components to be used is low, resulting in an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a discharge lamp lighting device and a light source device in which a rise in lamp temperature and a decrease in light output due to leakage current are suppressed.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp lighting apparatus for generating a discharge in a primary winding and a translucent bulb each having one end connected to a DC power supply and the other end connected to a switching element. At least one is provided with a step-up transformer having a secondary winding connected to a discharge lamp having a pair of electrodes provided on the outer surface of the light-transmissive bulb. A high-frequency high-voltage generating circuit for outputting a high voltage; and detecting means for detecting a voltage at the other end of the primary winding of the step-up transformer, wherein the primary voltage of the step-up transformer is changed according to the voltage detected by the detecting means. A control circuit for controlling the switching operation of the switching element so as to be controlled.

In the first aspect and the following invention, the definition of each configuration and each term is based on the following description, unless otherwise limited.

As the discharge lamp, one having all electrodes for generating a proper discharge along the outer surface of the light-transmitting bulb, and one having a part thereof along the outer surface of the light-transmitting bulb is used. Any of them may be used. The term “providing along the outer surface of the light-transmitting valve” means that the light-transmitting valve is directly attached to the light-transmitting valve, printed, or the like, which is formed in advance on an insulating sheet or the like and the insulating sheet is attached to the outer surface of the valve. May be. And the shape of the electrode provided along this outer surface,
The dimensions are not limited, and even when a pair of electrodes are provided outside, the portions facing each other are trapezoidal, rectangular,
Any shape such as a linear shape may be used. However, it is effective to use a pair of external electrodes having continuous or discontinuous curved portions at opposing portions in that the electric field is easily concentrated.

As the high-frequency high-voltage generating circuit, for example, an inverter, a chopper or the like can be mainly constituted. In this case, the high-frequency high-voltage generating circuit can be provided relatively simply and at low cost. However, in the present invention, the high-frequency high-voltage generating circuit may have another configuration. Further, the term "high frequency" means a range higher than the commercial frequency, and it is particularly advantageous to set the frequency to about 20 KHz or higher, which is higher than the audible frequency, in order to reduce the problem of audible noise. A particularly preferable range is 20 to 100 KHz in many cases in consideration of a reduction in switching loss of a switching element of a semiconductor switching element used in a high-frequency high-voltage generating circuit.
The high voltage broadly means higher than the voltage of the primary-side DC power supply, but is 500 V or more, more preferably 1 KV or more in order to ensure stable operation of the discharge lamp.

The switching element may be a bipolar transistor, a field effect transistor (FET), or the like, but is not limited thereto as long as it has a pair of main poles and a control pole.

The step-up transformer comprises a primary winding and a secondary winding in a desired turns ratio.
It does not matter whether there is a saturation characteristic or a leakage inductance component. Further, a tertiary winding that outputs a switching drive voltage may be provided. In this case, the present invention can be applied by replacing the other end of the secondary winding with the high voltage side of the tertiary winding on which the ringing component of the primary is superimposed.

The control circuit outputs a control output to a control pole of the switching element so as to control ON / OFF of the switching element in accordance with the output of the detecting means. This control circuit mainly performs PWM control on the high-frequency high-voltage generation circuit, but the control method is not limited to this as long as the control is such that a desired lamp current can be obtained.

The detecting means is configured to detect the voltage at the other end of the primary winding of the step-up transformer, and outputs the detected voltage to the control circuit.

Next, the operation of claim 1 will be described.
With the application of the DC voltage to the high-frequency high-voltage generating circuit, the switching element starts to be turned on / off by a desired starting circuit, and the high-frequency high-voltage generating circuit starts oscillating. Due to this oscillation, a voltage is applied between the pair of electrodes of the discharge lamp connected to the secondary winding side of the step-up transformer, discharge starts, and the discharge lamp is turned on.

When the discharge lamp starts lighting, a voltage obtained by superimposing the ringing of the voltage applied to the discharge lamp is applied to the switching element connected to the primary winding of the step-up transformer. This ringing appears remarkably when the voltage applied to the discharge lamp is pulsed.

Since the detecting means can simulately detect the lamp voltage on the secondary winding side from the ringing component superimposed on the primary winding side of the step-up transformer, the generation of leakage current on the secondary winding side occurs. Alternatively, a decrease in lamp voltage due to a rise in lamp temperature is detected as a voltage and output to the control circuit. In addition,
The detecting means for detecting the voltage may be constituted by components that are connected to the primary winding side, so that the applied voltage is lower than when the voltage is detected on the secondary winding side, and the withstand voltage characteristics are not so high. it can.

When the detection means detects a decrease in the lamp voltage, the control circuit controls on / off of the switching element, and performs feedback control so as to increase the lamp current so that the light output does not decrease. It is also possible to perform control so that the lamp voltage decreases when the voltage at the other end exceeds a desired value.

According to the discharge lamp lighting device of the first aspect,
By detecting the voltage on the other end side of the primary winding of the step-up transformer, the lamp voltage on the secondary winding side can be artificially detected and feedback control can be performed, so that the detection means for detecting the lamp voltage is simplified. In addition to this, it is possible to prevent a decrease in the light output of the lamp by detecting a leak current or a decrease in the lamp voltage due to an increase in the lamp temperature.

According to a second aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the detecting means of the control circuit detects the high-frequency current at the other end of the transformer primary winding as well as the voltage at the other end. The switching operation of the switching element is controlled by comparing the high-frequency current with the voltage at the other end.

The high-frequency current is obtained by artificially detecting a change in the lamp current on the secondary winding from a high-frequency component generated on the other end of the primary winding of the step-up transformer by a differentiating circuit or the like. Therefore, the detecting means can detect that the lamp current has dropped below the predetermined value by the high-frequency current at the other end of the primary winding.

The detecting means detects a voltage and a high-frequency current at the other end of the primary winding and compares these detected values. That is, the detecting means converts the high-frequency current to a voltage value and compares it with a desired reference voltage, and outputs a signal for increasing the lamp voltage to the control circuit when the converted voltage value of the high-frequency current falls below the reference voltage, and The circuit increases the lamp voltage by on / off control of the switching element. It is also possible to control the lamp voltage to decrease when the converted voltage value of the high-frequency current exceeds a desired upper limit voltage.
If the reference voltage is changed in correspondence with the voltage, the reference voltage to be compared with the high-frequency current decreases when the lamp voltage decreases, so that the signal output to the control circuit can be performed more quickly. Become.

According to the discharge lamp lighting device of the second aspect,
By detecting the high-frequency current on the primary winding side of the step-up transformer, the fluctuation of the lamp current on the secondary winding side is pseudo-detected, and feedback control is performed by comparing the high-frequency current and voltage on the primary winding side. Therefore, feedback control can be performed with good responsiveness even if a leakage current occurs or a light output decreases due to an increase in lamp temperature.

According to a third aspect of the present invention, at least one of the primary lamp and the light-transmitting bulb, one end of which is connected to a DC power supply and the other end of which is connected to a switching element, has at least one light-transmitting element for generating a discharge. A high-frequency transformer that includes a boost transformer having a secondary winding connected to a discharge lamp having a pair of electrodes provided on an outer surface of the bulb, and outputs a high-frequency high voltage from the secondary winding of the boost transformer by a switching operation of a switching element; A high-voltage generating circuit; and a detecting means for detecting a voltage and a high-frequency current at the other end of the primary winding of the step-up transformer, and detecting a power value by adding the detected voltage and the high-frequency current. The switching operation of the switching element is controlled such that the voltage and the high-frequency current on the primary side of the step-up transformer are controlled in accordance with the power value detected by the detecting means. Characterized in that it comprises a; and a control circuit for controlling.

The detecting means outputs a signal for varying the lamp voltage to a control circuit based on the power value obtained by adding the voltage on the other end of the primary winding and the high-frequency current, and the control circuit performs on / off control of the switching element. Increases the lamp voltage. That is, when the decrease in the light output is accompanied by a delay in the rise of the voltage pulse, the decrease in the lamp current and the decrease in the lamp voltage, one of the detection output, the voltage on the other end of the primary winding and the high-frequency current, Is larger than the detection output, the fluctuation of the power value obtained by adding both is larger, and the change in the input power to the lamp can be detected reliably, so that the signal output to the control circuit can be performed more reliably. Become.

Here, a description will be given of the fact that the delay in the rise of the voltage pulse causes a decrease in optical output. The voltage pulse has a higher frequency when the voltage rises sharply (or falls), so that the impedance decreases and the lamp power can be increased. However, when the impedance rises due to a change in the dielectric constant of the bulb accompanying a rise in the temperature of the lamp, the rise of the voltage pulse waveform is delayed, and the frequency is also lowered, so that the lamp power is reduced and the light output is reduced.

According to the discharge lamp lighting device of the third aspect,
By detecting the voltage and high-frequency current on the primary winding side of the step-up transformer and simulating the lamp power value on the secondary winding side and performing feedback control based on this power value, leakage current may occur. In addition, even if the light output decreases due to the increase in the lamp temperature, the feedback control can be reliably performed.

A light source device according to a fourth aspect of the present invention includes a carriage; and a pair of electrodes mounted on the carriage, at least one of which is provided on an outer surface of the light-transmitting bulb to generate a discharge in the light-transmitting bulb. A discharge lamp; and a discharge lamp lighting device according to any one of claims 1 to 3.

According to the light source device of the fourth aspect, it is possible to provide a light source device provided with the discharge lamp lighting device according to any one of the first to third aspects.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a discharge lamp lighting device according to the first embodiment, and FIG. 2 is an explanatory diagram showing an image reading device.

As shown in FIG. 2, an image reading apparatus, which is an office automation device such as a copying machine, an image scanner, or a facsimile, has a case body 1 and a glass document mounting surface in the case body 1. The original mounting surface 2 is provided with a carriage 3 on the lower surface thereof. The carriage 3 has a light source unit 4 for reading an original and a red light source 4 which moves with the light source unit 4 at a predetermined distance. A light receiving means 5 such as a CCD for reading only (R), green (G) and blue (B) or green (G) is provided.

The light source unit 4 has a carriage 3. The carriage 3 irradiates an original from a white fluorescent lamp 6 and a white fluorescent lamp 6 of an external electrode xenon lamp as a low-pressure discharge lamp, and is reflected by the original. And a mirror 7 for reflecting the reflected light toward the light receiving means 5. If the light receiving means 5 reads only green (G), a YG (yellow green) fluorescent lamp is used.

Further, there is provided a circuit device 9 having signal processing means for processing an output signal of the light receiving means 5 to form an image signal and a discharge lamp lighting device 8 for lighting the white fluorescent lamp 6.

The light source unit 4 and the light receiving means 5
And the original placing surface 2 is relatively scanned. That is, while one or both move in the opposite direction, the light receiving means 5 receives the reflected light from the original fringe surface at right angles to the moving direction.

Here, the discharge lamp lighting device 8 will be described with reference to FIG.

As shown in FIG. 1, the discharge lamp lighting device 8
In FIG. 1, a smoothing capacitor C1 is connected in parallel to a DC power supply E, and a single-type inverter circuit 11 as a high-frequency high-voltage generating circuit is connected to the capacitor C1. The inverter circuit 11 includes a parallel resonance circuit 12 including a primary winding Tr1a of a step-up type insulation transformer Tr1 as an inductor and a capacitor C2 connected in parallel with the primary winding Tr1a, and a field effect transistor Q1 as a switching element. And is connected in parallel to the capacitor C1.

The drive circuit 13 is connected to the gate of the field effect transistor Q1 via the resistor R1.

Further, the secondary winding Tr1 of the transformer Tr1
b is connected to one external electrode FL1 of the white fluorescent lamp FL via a resistor R2 and to the other external electrode FL2. Note that the outer electrode FL2 is grounded.

A control circuit 13 is connected in parallel to the gate terminal of the field-effect transistor Q1, and the control signal of the control circuit 13 controls on / off of the field-effect transistor Q1 so that the discharge lamp lighting device 8 is turned on. Is P
WM control is performed.

The control circuit 13 includes detection means 14 for detecting the voltage on the primary winding Tr1a side. The detecting means 14 includes a field effect transistor Q1 and a primary winding Tr1a.
A resistor R having one end connected to the connection point and the other end grounded
5 and a series circuit of the resistor R6, one end of which is connected in parallel to the resistor R6 via the diode D1, the other end of which is constituted by a resistor R7 grounded and a capacitor C3 connected in parallel to the resistor R7. The resistance R of this detection means 14
7 is connected to the control circuit 13, and outputs a signal of the detected voltage to the control circuit 13.

Next, the operation of the above embodiment will be described.

The DC of the DC power supply E is smoothed by the capacitor C 1 and supplied to the inverter circuit 11. In the inverter circuit 11, the drive circuit 13 turns the voltage effect transistor Q1 on and off, and the step-up transformer Tr1.
Oscillates with the inductance of the capacitor C2 and applies a high-frequency voltage to the fluorescent lamp FL in a pulsed manner, so that the fluorescent lamp FL is lit at a high frequency by a pulse lighting method.

The voltage between the drain and source of the field effect transistor Q1 is divided by the resistors R5 and R6 of the detecting means 14 to detect the voltage on the primary side of the transformer Tr1, and a signal of this voltage is sent to the control circuit 13. input. That is, when the fluorescent lamp FL starts lighting, a voltage in which ringing of the pulse-like voltage applied to the fluorescent lamp FL is superimposed is applied to the voltage effect transistor Q1 connected to the primary winding Tr1a of the step-up transformer Tr1. The voltage detected by the detection means 14 can detect the lamp voltage on the secondary winding Tr1b side in a pseudo manner. In this case, it is possible to provide a detecting means also on the secondary winding Tr1b side. However, since the voltage on the secondary winding Tr1b side is boosted, an element having a high withstand voltage characteristic is used for the detecting means provided. It is necessary to use the primary winding Tr in this embodiment.
Since the voltage on the 1a side is detected, there is an advantage that an element having a relatively low withstand voltage characteristic can be used.

When the voltage detected by the detecting means 14 is equal to or higher than a predetermined value, the capacitor C3 is charged and the control circuit 13
A predetermined voltage signal is output to the control circuit 13 so that the control circuit 13 performs normal on / off control of the field-effect transistor Q1. A signal is output to the control circuit 13
Is subjected to feedback control so as to increase the lamp current by changing the on-duty.

Since the discharge lamp lighting device 8 is incorporated in the circuit device 9, the harness or the lamp itself that connects the fluorescent lamp FL and the circuit device 9 is connected to a metal member such as a chassis or a reflector of the circuit device 9. Even if the light output of the lamp decreases due to the leakage of the current, the lamp voltage is detected by the detection means 14 in a simulated manner. Therefore, the feedback control by the control circuit 13 appropriately increases the lamp current and reduces the light output. Can be suppressed.

Further, even if the light output is decreased due to the increase in the lamp temperature, the decrease in the light output can be suppressed similarly since the lamp voltage is detected in a pseudo manner.

The negative side of the DC power supply E is grounded. Although the step-up insulating transformer Tr1 is composed of primary and secondary windings, the step-up transformer Tr1 may be provided with a tertiary winding for feedback control of the switching element. What is necessary is just to connect so that the voltage of the high voltage side of a tertiary winding may be detected.

Next, a discharge lamp lighting device according to a second embodiment will be described with reference to FIG.

FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to a second embodiment. The basic configuration is the same as that of the discharge lamp lighting device shown in FIG.

In this embodiment, as shown in FIG. 3, a detecting means 15 is provided in place of the detecting means 14 shown in FIG.

The detecting means 15 comprises a field effect transistor Q
1, a series circuit of a resistor R5 and a resistor R6 for dividing the voltage between the drain and the source, one end of which is connected in parallel to the resistor R6 via the diode D1, and the other end is connected in parallel to the grounded resistor R7 and the resistor R7. The voltage of the primary side of the transformer Tr1 is detected by the connected capacitor C3, and the high-frequency current is detected by the series circuit of the resistor R8, the capacitor C4, and the resistor R9 connected in parallel with the series circuit of the resistor R5 and the resistor R6. It is configured. That is, the resistor R8 and the capacitor C4 constitute a differentiating circuit. The high-frequency current of the high-frequency current component is generated and detected by the resistor R9 as a voltage, and the high-frequency current component on the primary winding Tr1a side is detected. A resistor R7 'having one end connected in parallel to a resistor R9 via a diode D1'
And an integrating circuit composed of the capacitor C3 '.

The detecting means 15 compares the voltage output generated at the resistor R7 with the integrated voltage output of the high-frequency current generated at the resistor R7 'using an operational amplifier CP.
Is output to the control circuit 13.

Next, the operation of the above embodiment will be described.

As in the first embodiment, the fluorescent lamp FL
Is turned on, the detecting means 15 detects the voltage and the high-frequency current, and compares the detected voltage output with the operational amplifier CP. That is, the detecting means 15 converts the high-frequency current into a voltage value, compares the voltage with the voltage, and outputs a signal from the operational amplifier CP to the control circuit 13 so as to increase the lamp voltage when the converted voltage value of the high-frequency current falls below the voltage. Then, the control circuit 13 increases the lamp voltage by turning on / off the switching element so as to increase the lamp voltage.
Perform WM control.

According to the discharge lamp lighting device 8 of the second embodiment, by detecting the high-frequency current on the primary winding Tr1a side of the step-up transformer Tr1, the fluctuation of the lamp current on the secondary winding Tr1b side is simulated. Since the feedback control is performed by detecting and comparing the high-frequency current and the voltage, the feedback control can be performed with good responsiveness even if a leak current occurs or a light output decreases due to an increase in lamp temperature.

Next, a discharge lamp lighting device according to a third embodiment will be described with reference to FIG.

FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to the third embodiment. The basic configuration is the same as that of the discharge lamp lighting device shown in FIG.

In this embodiment, as shown in FIG. 3, a detecting means 1 for detecting a power value is used instead of the detecting means 14 shown in FIG.
6.

The detecting means 16 comprises a field effect transistor Q
A resistor R10, a resistor 11 and a resistor R12, one end of which is connected to the connection point of the primary winding Tr1a and the other end and the other end is grounded.
, A capacitor C connected in parallel with the resistor R11
5. One end is connected in parallel to the resistor R12 via the diode D1, the other end is connected to the grounded resistor R7, and the capacitor C3 is connected in parallel to the resistor R7. One end of the resistor R7 of the detecting means 16 is connected to the control circuit 1
3 and outputs the detected power value signal to the control circuit 13.

Next, the operation of the above embodiment will be described.

As in the first embodiment, the fluorescent lamp FL
, The detecting means 16 detects the voltage and the high-frequency current, adds the detected voltage and the high-frequency current as a power value, and generates the power value as a voltage output to the resistor R12. A voltage output as this power value is output to an integrating circuit composed of a resistor R7 and a capacitor C3.

When the power value detected by the detecting means 16 is equal to or more than a predetermined value, the capacitor C3 of the integrating circuit is charged,
A predetermined voltage signal is output to the control circuit 13 and the control circuit 1
3, the normal on / off control of the field effect transistor Q1 is performed, but when the power value becomes equal to or less than a predetermined voltage value, a voltage signal equal to or less than the predetermined value is output to the control circuit 13 and the control circuit 13 is turned on. Feedback control is performed so as to increase the lamp current by changing the duty.

According to the discharge lamp lighting device of the third embodiment, the lamp power on the secondary winding Tr1b side is simulated by detecting the voltage and the high-frequency current on the primary winding Tr1a side of the step-up transformer Tr1. However, since feedback control is performed based on this power value, leakage current may occur,
Even if the light output decreases due to the increase in the lamp temperature, the feedback control can be reliably performed.

[0067]

According to the discharge lamp lighting device of the first aspect, feedback control is performed by detecting the voltage on the primary winding side of the step-up transformer to detect the lamp voltage on the secondary winding side. Therefore, the detection means for detecting the voltage on the primary winding side can be simply configured, and the occurrence of leakage current or a decrease in the lamp voltage due to an increase in the lamp temperature is detected. It is possible to suppress a decrease in light output.

According to the discharge lamp lighting device of the second aspect,
By detecting the high-frequency current on the primary winding side of the step-up transformer, the fluctuation of the lamp current on the secondary winding side is pseudo-detected, and feedback control is performed by comparing the high-frequency current and voltage on the primary winding side. Therefore, feedback control can be performed with good responsiveness even if a leakage current occurs or a light output decreases due to an increase in lamp temperature.

According to the discharge lamp lighting device of the third aspect,
By detecting the voltage on the primary winding side and the high-frequency current of the step-up transformer, the lamp power on the secondary winding side is detected in a pseudo manner, and feedback control is performed based on this power value. Even if the light output decreases due to the increase in the lamp temperature, the feedback control can be reliably performed.

According to the light source device of the fourth aspect, it is possible to provide a light source device provided with the discharge lamp lighting device according to any one of the first to third aspects.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the image reading apparatus according to the first embodiment;

FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to the second embodiment;

FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to the third embodiment;

[Explanation of symbols]

3 Carrier, 8 Discharge lamp lighting device, 11 Inverter circuit for generating high frequency, 13 Control circuit, 14
... Detecting means 14, E ... DC power supply, FL ... Fluorescent lamp as discharge lamp, FL1, FL2 ... Pair of electrodes, Tr1
... step-up transformer, Q1 ... field-effect transistor as a switching element.

Claims (4)

[Claims] 1. A primary winding having one end connected to a DC power supply and the other end connected to a switching element, and at least one of a pair provided on an outer surface of the light-transmitting bulb for generating a discharge in the light-transmitting bulb. A high-frequency high-voltage generating circuit for outputting a high-frequency high voltage from the secondary winding of the boosting transformer by a switching operation of a switching element; and a boosting transformer. Control means for detecting the voltage at the other end of the primary winding, and controlling the switching operation of the switching element such that the primary voltage of the step-up transformer is controlled according to the voltage detected by the detection means. A discharge lamp lighting device, comprising: a circuit; 2. The detecting means of the control circuit detects a high-frequency current at the other end of the primary winding of the transformer together with a voltage at the other end, and compares the detected high-frequency current with a voltage at the other end to perform switching. The discharge lamp lighting device according to claim 1, wherein the switching operation of the element is controlled. 3. A primary winding having one end connected to a DC power supply and the other end connected to a switching element, and at least one of a pair provided on an outer surface of the light-transmitting bulb to generate a discharge in the light-transmitting bulb. A high-frequency high-voltage generating circuit for outputting a high-frequency high voltage from the secondary winding of the boosting transformer by a switching operation of a switching element; and a boosting transformer. And a detecting means for detecting the voltage and the high-frequency current at the other end of the primary winding, and detecting the power value by adding the detected voltage and the high-frequency current. A control circuit for controlling the switching operation of the switching element such that the voltage and the high-frequency current on the primary side of the step-up transformer are controlled accordingly. A lighting device for a discharge lamp, comprising: 4. A discharge lamp mounted on the carriage and having a pair of electrodes at least one of which is provided on an outer surface of the light-transmitting bulb to generate a discharge in the light-transmitting bulb; 4. A light source device comprising: the discharge lamp lighting device according to any one of 1 to 3;