JP2000106293A - Lighting device for rare gas discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device for a rare gas discharge lamp, capable of increasing the light quantity of the rare gas discharge lamp, without varying the envelope size of the rare gas discharge lamp or increasing the tube inputs. SOLUTION: This device includes a rare-gas discharge lamp DL, having a pair of strip-like external electrodes 5, 6 which are spaced apart and arranged on the outer peripheral surface of an envelope 1 having a light-emitting layer on its inner surface, and a high-frequency voltage generating circuit HA which has a constant power circuit PST, including a switching element QA on the input side of an output transformer TRA and generating pulsed high frequency voltages on the output side of the output transformer according to the switching action of the switching element based on the imparting and stopping of a drive signal. The rare gas discharge lamp DL is connected to the output side of the high-frequency voltage generating circuit HA, and power on the input side of the high-frequency voltage generating circuit, when the rare gas discharge lamp is lighted, is controlled so as to become almost constant by the constant power circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a rare gas discharge lamp, and more particularly to a rare gas discharge lamp in which a pair of strip-shaped external electrodes are arranged on the outer peripheral surface of a glass bulb having a light emitting layer on the inner surface. The present invention relates to an improvement of a lighting device connected to a circuit.

[0002]

2. Description of the Related Art The present applicant has previously proposed a rare gas discharge lamp L shown in FIGS. In FIG. 1, reference numeral 1 denotes a straight tubular envelope which is hermetically sealed by a glass bulb, for example, and has a light emitting layer 2 made of a phosphor such as a rare earth phosphor or a halophosphate phosphor on the inner surface thereof. Is formed.
In particular, the light emitting layer 2 is formed with an aperture 2a having a predetermined opening angle over substantially the entire length. And
The sealing structure of the envelope 1 is formed by sealing a disk-shaped sealing glass plate at the end of a glass bulb. It can also be constituted by files. still,
A predetermined amount of a rare gas containing xenon as a main component that does not contain metal vapor such as mercury is sealed in the enclosed space of the envelope 1.

[0003] A sheet structure 3 is wound around the outer peripheral surface of the envelope 1 so as to be in close contact therewith. This sheet structure 3
For example, an insulative translucent sheet 4 having a length substantially equal to the entire length of the envelope 1 and one surface of the translucent sheet 4 are spaced apart from each other by a predetermined distance. A pair of strip-shaped external electrodes 5 and 6 made of a bonded metal member, terminals 51 and 61 led out from ends of the external electrodes 5 and 6, and one surface of the translucent sheet 4 are provided. And an adhesive layer 9 formed. When the sheet structure 3 is attached to the envelope 1, a first opening 7 is provided between the one side edges 5a and 6a of the external electrodes 5 and 6, and the first electrodes 7 and 6 A second opening 8 is formed between the other side edge portions 5b and 6b, and light from the light emitting layer 2 mainly emits light from the aperture portion 2.
a to the outside through the first opening 7. or,
In the sheet structure 3, the translucent sheet 4 is preferably made of, for example, polyethylene terephthalate (PET) resin.
Other resins such as polyester resins can also be used.

The above-mentioned sheet structure 3 is mounted on the outer peripheral surface of the envelope 1 so that the external electrodes 5 and 6 are located between the envelope 1 and the translucent sheet 4 (see FIG. 1). Winding). This sheet
The mounting of the structure 3 to the envelope 1 is performed, for example, as shown in FIG. First, the sheet structure 3 is arranged on the stage 10 in an expanded state. Next, the envelope 1 is arranged at one end 4a of the translucent sheet 4 in the sheet structure 3, and
The envelope 1 is formed by a pair of driven rollers 11
After the stage 10 is set so as to be pressed against the stage 4, the stage 10 is slightly moved in the M direction and then moved in the N direction. Then, the sheet structure 3 relatively rolls on the translucent sheet 4, and the outer peripheral surface of the sheet structure 3 is mounted by being wound. In the sheet structure 3, the external electrodes 5 and 6 are adhered to the outer peripheral surface of the envelope 1 by using an adhesive layer formed on the surface thereof, and the translucent sheet 4 is Using the adhesive layer 9 formed on one side, it is adhered to the outer peripheral surface of the envelope 1 at the time of winding, and the respective ends 4a and 4b are overlapped and adhered at the second opening 8. .

The rare gas discharge lamp L is lit by, for example, a lighting device shown in FIG. This lighting device generates, for example, a high-frequency voltage having a frequency of about 30 KHz and a voltage of about 2500 V0 _-P , and an inverter circuit H whose output waveform is substantially a sine wave, and a DC power supply to the inverter circuit H. The inverter circuit H includes a switching element Q such as a transistor for controlling the supply and a smoothing capacitor C. The inverter circuit H includes, for example, primary coils TRa and T.
An oscillation transformer TR having Rb, a secondary coil TRc, and an exciting coil TRd; a choke coil CH connected between the middle point of the primary coils TRa, TRb and the switching element Q; and a primary coil TRa, TRb. First and second switching elements, for example, first and second transistors Qa and Qb, and first and second transistors Qa and
It comprises resistors Ra and Rb connected between the base of Qb and the exciting coil TRd. And, Inver
The external electrodes 5 and 6 of the rare gas discharge lamp L are connected to the output side (secondary coil TRc) of the data circuit H.

In this lighting device, when a DC power source obtained by, for example, full-wave rectification of a commercial power source is connected between the terminals Ta and Tb and a drive signal is applied to the terminal Tc at appropriate intervals, the switching element Q is turned ON, By turning on and off the first and second transistors Qa and Qb in a timely manner,
The high-frequency high voltage described above is generated in the secondary coil TRc of the oscillation transformer TR and applied to the external electrodes 5 and 6 of the rare gas discharge lamp L. Thus, unlike the rare gas discharge lamp L, which is lit by one discharge path along the longitudinal direction of the envelope, like a discharge lamp using a hot cathode or a cold cathode, the external electrodes 5, 6 During this period (in a direction substantially perpendicular to the longitudinal direction of the envelope 1), an infinite number of discharge paths are formed, so that the light is emitted in a striped state. In this state, the light emitting layer 2 is excited by a rare gas excitation line to emit light, and light is emitted from the aperture 2a to the outside through the first opening 7.

In particular, since no mercury is used in the rare gas discharge lamp L, there is a characteristic that the light quantity rises sharply after lighting and reaches almost 100% at the same time as lighting. ing. For this reason, it is suitable as a light source for reading originals of OA equipment such as a facsimile, an image scanner, and a copying machine.

[0008]

As described above, when the rare gas discharge lamp L is applied to a document irradiating apparatus, the density of the radiated light of the light emitting layer 2 is increased by employing an aperture structure. Therefore, the illuminance of the document surface can be increased and the document can be read reliably.

However, recently, OA equipment has tended to further increase the document feeding speed in order to increase the processing capacity and increase the efficiency of office work, and the rare gas discharge lamp L described above is used as it is. If applied, the reading accuracy (resolution) of the original document will be impaired.

Therefore, in order to cope with an increase in the speed of a document, the light output (light amount) of the rare gas discharge lamp may be increased so as to further increase the illuminance on the document surface. For example, if the tube diameter of the envelope 1 is increased and the tube input (power) is increased, the amount of light can be relatively easily increased. Since the interval is as narrow as about 6 to 12 mm, there is a problem that it is difficult to arrange a rare gas discharge lamp having a tube diameter larger than the interval.

On the other hand, if the tube input of the rare gas discharge lamp is increased without changing the size, a certain amount of increase in the amount of light can be expected, but the increase in the amount of light is small for increasing the tube input. Not only is it not possible to expect sufficient reading accuracy, but also because the load on the inverter circuit H increases due to an increase in tube input, the cost of the lighting device increases.

[0012] Therefore, an object of the present invention is to provide a rare gas discharge lamp which can further increase the light quantity of the rare gas discharge lamp without changing the size of the envelope of the rare gas discharge lamp or increasing the tube input. A lighting device for a discharge lamp is provided.

[0013]

Therefore, in order to achieve the above-mentioned object, the present invention provides a pair of band-shaped external electrodes made of a metal member on the outer peripheral surface of an envelope having a light emitting layer on the inner surface.
A rare gas discharge lamp which is spaced apart from each other so as to form first and second openings over substantially the entire length of the envelope, and a constant power supply including a switching element on the input side of the output transformer A high-frequency voltage generating circuit that generates a pulsed high-frequency voltage on the output side of the output transformer based on the switching operation of the switching element by applying / stopping the drive signal. The output side of the generating circuit is connected so that a pulsed high-frequency voltage is applied to a pair of external electrodes, and the power on the input side of the high-frequency voltage generating circuit in the lighting state of the rare gas discharge lamp is
It is characterized in that it is controlled to be substantially constant by a constant power circuit.

According to a second aspect of the present invention, a pair of band-shaped external electrodes made of a metal member are provided on the outer peripheral surface of an envelope having a light-emitting layer on the inner surface, over a substantially entire length of the envelope. , A rare gas discharge member which is disposed so as to be spaced apart from each other so as to form a second opening, and which is provided with a translucent insulating member on the outer peripheral surface of the envelope so as to cover the external electrode. A high-frequency device that includes a lamp and a constant-power circuit including a switching element on the input side of the output transformer, and generates a pulsed high-frequency voltage on the output side of the output transformer based on the switching operation of the switching element by applying and stopping the drive signal. A voltage generating circuit, wherein the rare gas discharge lamp is connected to an output side of the high frequency voltage generating circuit so that a pulsed high frequency voltage is applied to a pair of external electrodes, and a lighting state of the rare gas discharge lamp High frequency voltage generation times at The power of the input side, and controls to be substantially constant by the constant power circuit.

According to a third aspect of the present invention, in the rare gas discharge lamp, the radiated light from the light emitting layer is mainly emitted outside from the first opening, and at least the external electrode According to a fourth aspect of the present invention, in the rare gas discharge lamp, a deformed portion is formed on any of the side edges.
The insulating member is constituted by a protective tube made of a light-transmitting sheet or a heat-shrinkable resin.

According to a fifth aspect of the present invention, the high-frequency voltage generating circuit includes at least an output transformer having primary and secondary coils, and a switching element connected in series to the primary coil of the output transformer. And a capacitor connected substantially in parallel to a series circuit of a primary coil of the output transformer and a constant-power circuit, wherein the constant-power circuit includes at least:
A switching element connected in series to the primary coil of the output transformer, a current detection circuit connected in series to the switching element, a comparison circuit for comparing an output voltage corresponding to the current detected by the current detection circuit with a reference voltage, and a comparison circuit Driving the switching element to be turned off based on a signal output when the output voltage of the current detection circuit becomes higher than the reference voltage, and then outputting a drive signal for turning on the switching element after a predetermined period of time A seventh aspect of the present invention is that the constant power circuit includes at least a switching element connected in series to a primary coil of an output transformer, a current detection circuit connected in series to the switching element, A comparison circuit for comparing an output voltage corresponding to the current detected by the detection circuit with a reference voltage, and a current detection circuit After the switching element is turned off based on a phase-advance circuit including a capacitor and a resistor connected between the comparison circuit and a signal output when the output voltage of the current detection circuit becomes higher than the reference voltage in the comparison circuit. And a drive circuit for outputting a drive signal for turning on the switching element after a predetermined period of time, wherein the delay of the signal in the comparison circuit, the drive circuit, and the like is corrected by the phase advance circuit. And

An eighth invention of the present invention is characterized in that the drive circuit for applying a drive signal for keeping the off period of the switching element constant is constituted by a monostable multivibrator, According to the invention, the off period of the switching element is defined as the first cycle of the free oscillation of the lamp current generated by the effective inductance of the secondary coil of the output transformer and the effective capacitance when the rare gas discharge lamp is turned on. Preferably, the comparison circuit of the constant power circuit is mainly provided to an operational amplifier by setting the comparison circuit of the constant power circuit to a rebound period in which the lamp current reverses from the first peak point of the free oscillation. A reference voltage is applied to a non-inverting input terminal of the operational amplifier, and an output voltage of the current detection circuit is applied to an inverting input terminal of the operational amplifier.
The invention according to a first aspect is characterized in that a distribution voltage of a power supply voltage is applied as a bias voltage to an inverting input terminal of an operational amplifier in the constant power circuit.

Further, a twelfth aspect of the present invention provides at least an output transformer having primary and secondary coils, a switching element connected in series to the primary coil of the output transformer, a current detection circuit connected in series to the switching element, A comparison circuit comprising an operational amplifier for comparing an output voltage corresponding to a current detected by the circuit with a reference voltage, and a switching element based on a signal output when the output voltage of the current detection circuit becomes higher than the reference voltage in the comparison circuit And a high-frequency voltage generating circuit including a constant-power circuit including a driving circuit that outputs a driving signal for turning on the switching element after a predetermined time, and connected to an output side of the high-frequency voltage generating circuit. A pair of band-shaped external electrodes made of a metal member are formed on the outer peripheral surface of the envelope having the light emitting layer on the inner surface. A rare gas discharge lamp, which is spaced apart from each other so that the first and second openings are formed over substantially the entire length of the lamp, and a back electromotive force voltage generated in a primary coil of the output transformer is preset. And a reference voltage lowering circuit for lowering the reference voltage applied to the comparing circuit based on the detection result.

[0019]

Next, a first embodiment of a lighting device for a rare gas discharge lamp according to the present invention will be described with reference to FIGS. The same parts as those in the prior art shown in FIGS. 16 to 20 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this figure, the characteristic part of this embodiment is that the deformed portions 5A, 6A are formed at the side edges 5b, 6b of the external electrodes 5, 6 forming the second opening 8 in the rare gas discharge lamp DL, Other side edges 5a, 6 of external electrodes 5, 6
a is formed in the form of a straight line, and the high-frequency voltage generating circuit is composed of a high-frequency voltage generating circuit HA for generating a pulsed high-frequency voltage, and the current on the input side of the high-frequency voltage generating circuit HA is preset. The switching element is turned off when the value exceeds the set value, and then the switching element is turned on after a predetermined period of time, thereby adding a constant power circuit for making the power on the input side constant. One of the external electrodes 5 and 6 of the rare gas discharge lamp DL connected to the output side of the high-frequency voltage generating circuit HA is grounded on one of the external electrodes 6 on which the deformed portions 5A and 6A are formed. is there.

In the rare gas discharge lamp DL described above, triangular shaped portions 5A and 6A are formed on the external electrodes 5 and 6 so as to have periodicity. For example, the outer diameter of the envelope 1 is 8 m
In the case of m, the width including the deformed portions 5A and 6A is 8 mm, the pitch of the deformed portions 5A and 6A is 4 mm, and the deformed portions 5A and 6A.
It is desirable that the height of (the apex of the triangular portion) be set to a size of about 1.5 mm, but it can be changed as appropriate depending on the specifications of the rare gas discharge lamp and the lighting device. The intervals between the vertices of the deformed portions 5A, 6A formed on the side edges 5b, 6b of the external electrodes 5, 6 are set to be substantially the same over the entire length. The opening width (interval) of the first opening 7 is also set to be substantially the same over the entire length.

As a constituent member of the envelope 1 of the rare gas discharge lamp DL, any material can be used as long as it is a material having a large dielectric constant, capable of reliably maintaining airtightness, and having translucency. For example, lead glass having a relatively large dielectric constant and barium glass containing no lead are recommended among glasses. The thickness is set in the range of 0.2 to 0.7 mm (preferably in the range of 0.4 to 0.7 mm), and in this range, desired productivity and optical characteristics can be obtained. However, when the wall thickness is less than 0.4 mm, particularly less than 0.2 mm, the mechanical strength of the envelope 1 is extremely reduced.
The defective rate due to glass breakage in the production process by mass production equipment increases. Conversely, when the wall thickness exceeds 0.7 mm, a striped discharge state is visually observed and released from the aperture portion 2a. Flickering occurs in the emitted light. Therefore, it is desirable to set the thickness of the envelope 1 within the above range.

The inner space of the envelope 1 is filled with a rare gas containing xenon gas as a main component, and its filling pressure is set, for example, in the range of 83 to 200 torr. In this range, the effects of improving starting characteristics, light output (original surface illuminance), and flicker can be obtained. However, when the sealing pressure is less than 83 Torr, the effect of improving the light output becomes insufficient. Conversely, when the sealing pressure exceeds 200 Torr, not only the starting characteristics are impaired, but also the striped discharge state is reduced. The light emitted from the aperture portion 2a is visually observed and flickers. Therefore, it is desirable to set the rare gas charging pressure within the above range.

The light emitting layer 2 may be composed of only one kind of phosphor to be used depending on the use of the rare gas discharge lamp.
It is composed of a mixture of more than one species. For example, in the case of the three-wavelength emission type, for example, a europium-activated barium magnesium aluminate phosphor having an emission spectrum in a blue region, a cerium / terbium-activated lanthanum phosphate phosphor having an emission spectrum in a green region, It is formed of a mixed phosphor obtained by mixing europium-activated yttrium-gadolinium phosphor having an emission spectrum in the red region, and the attached amount is set in the range of 5 to 30 mg per 1 cm ² . In this range, a sufficient amount of light (light output) can be obtained, but if the amount of adhesion is less than 5 mg, the illuminance of the original surface becomes insufficient due to insufficient amount of light. It becomes difficult to form a light emitting layer. Therefore, it is desirable that the amount of the light-emitting layer 2 attached be set within the above range.

Further, first and second openings 7 and 8 are formed in the separated portions of the external electrodes 5 and 6, respectively.
The respective opening angles θ ₁ and θ ₂ are set in a relation of θ ₁ > θ ₂ . The opening angle θ ₁ of the first opening 7 is 60 to 90
It is desirable that the opening angle θ ₂ of the second opening 8 be about 55 °. However, the opening angle θ ₁ of the first opening 7 can be set outside the above range depending on the application, and the second opening 8 is desirably narrow enough not to cause dielectric breakdown, for example, at least about 2 mm. It is recommended that the separation distance be maintained. The opening angle of the aperture 2a is set substantially equal to the opening angle θ1 of the _first opening 7.

On the other hand, a high-frequency voltage generating circuit HA for generating a pulsed high-frequency voltage includes, for example, an output transformer TRA having a primary coil TRa and a secondary coil TRc, and an electric field effect connected in series to the primary coil TRa of the output transformer TRA. And a constant power circuit PST including a switching element QA such as a transistor (FET).
The input side (primary coil TR) of this high-frequency voltage generating circuit HA
The capacitor CA and the DC power supply EB are connected to the “a” side, and the rare gas discharge lamp DL is connected to the output side (the secondary coil TRc side), and the external electrode 6 of the rare gas discharge lamp DL is grounded. .

The constant power circuit PST of the above high-frequency voltage generating circuit HA, for example outputs a switching element QA connected in series to the primary coil TRa of the transformer TRA, the current detection circuit consisting of resistor R ₁ connected in series to the switching element QA 30; a phase-advancing circuit 40 including a capacitor C ₁ and resistors R ₂ and R ₃ connected to the current detection circuit 30; an operational amplifier OP and resistors R ₄ and R ₅ for hysteresis; Resistor R at terminal (+)
₄ , a reference voltage Vref, a comparison circuit 50 having an inverting input terminal (-) connected to the output terminal of the phase advance circuit 40, a monostable multivibrator M and a capacitor for setting the off time of the switching element QA. C ₂ and a resistor R ₆ ,
After off operation of the switching elements QA on the basis of a signal output when the output voltage corresponding to the current detected by the current detecting circuit 30 in the comparison circuit 50 becomes higher than the reference voltage Vref, the capacitor C _2, a resistor R A drive circuit 2 for outputting a drive signal (gate signal) for turning on the switching element QA after a predetermined time set by ₆
0A. The drive circuit 20A applies a substantially square-wave drive signal to the gate of the switching element QA.

A rare gas discharge lamp DL is connected to the output side of the high-frequency voltage generating circuit HA so that a pulsed high-frequency voltage is applied to its external electrodes 5 and 6. One of the external electrodes 6 is grounded. In particular, the off period of the switching element QA based on the drive signal from the drive circuit 20A is generated by the effective inductance on the secondary coil TRc side of the output transformer TRA and the effective capacitance when the rare gas discharge lamp DL is turned on. Within the first cycle of the free oscillation of the lamp current (t ₁ + t ₂
(During the period), preferably during a bounce period (t ₂ ) in which the direction of the lamp current is reversed from the first peak point of the free oscillation.

The lighting device configured as described above operates as follows. First, when the DC power supply EB is connected to the input side of the high-frequency voltage generating circuit HA, the capacitor CA is charged. In this state, as shown in FIGS. 4A and 5B, a drive signal of a square wave (a gate of the switching element QA has a stray capacitance) is provided from the drive circuit 20A to the gate of the switching element QA. As a result, the switching element QA is turned on. By this ON operation, the primary coil TRa of the output transformer TRA from the capacitor CA and the DC power supply EB,
FIG. 4 shows the switching element QA and the current detection circuit 30.
As shown in (b), a primary current (drain current Ip) that increases almost linearly flows, and electromagnetic energy is accumulated in the output transformer TRA, and at the same time, the current detection circuit 3
0 to resistor R ₁ and a voltage drop due to the drain current Ip (output voltage) is generated. This output voltage is applied to the inverting input terminal (-) of the operational amplifier OP in the comparison circuit 50 via the phase advance circuit 40. A voltage (Ip · R ₁ ) corresponding to a preset value of the drain current Ip is applied as a reference voltage Vref to the non-inverting input terminal (+) of the operational amplifier OP, and the output voltage of the current detection circuit 30 is This is compared with the reference voltage Vref. When the output voltage of the current detection circuit 30 increases with time and becomes higher than the reference voltage Vref, a signal that changes from high level to low level is output to the output side of the operational amplifier OP. This output signal is input to the monostable multivibrator M of the drive circuit 20A. As a result, since the output side of the monostable multivibrator M is inverted from the high level to the low level, no gate signal is given to the gate of the switching element QA, and the switching element QA is turned off. become.

Next, when the switching element QA is turned off, the secondary coil TR is generated based on the action of the electromagnetic energy stored in the primary coil TRa of the output transformer TRA.
c, a pulse-like high-frequency voltage is generated by the winding ratio between the primary coil TRa and the secondary coil TRc, and the rare gas discharge lamp D
L is applied to the external electrodes 5 and 6. When the electric field concentrates on the deformed portions 5A and 6A of the external electrodes 5 and 6, a discharge is generated between the external electrodes and the rare gas discharge lamp DL
Becomes the lighting state, the lamp current Ib flows in FIG. 4 (c) and FIG. 5 period t ₁ of the first half of each one period of the repetition period as shown in (a) (T), a rare gas discharge lamp Since the DL forms a capacitor, electric charges are accumulated in the discharge lamp. When the lamp current Ib becomes zero, stored in the rare gas discharge lamp DL charge the rebound period t ₂ as a lamp current Ib, to flow in the direction opposite to the direction of the period t _1.

On the other hand, after the switching element QA is inverted to the OFF state, the drive circuit 20A and the capacitor C ₂ resistor R
After a certain time set by ₆ , a gate signal is applied again to the switching element QA. Lamp flowing from that this time is set in the first half of the aforementioned rebound period t _2, the switching element QA at the timing is turned on, the lamp current Ibj indicated by hatching in FIG. 5 (a), the period t ₂ It flows superimposed on the current. Incidentally, when lags period t ₂ bounce grant timing of the drive signal to the switching elements QA, the lamp current Ib 5
In (a), damping oscillation as indicated by the dotted line is caused, and the lamp current Ibj indicated by the oblique line stops flowing. As described above, the superposition of the lamp current Ibj causes the rare gas discharge lamp DL to emit light (φ) as shown in FIGS. 4D and 5C, and the brightness φ also increases in accordance with the increase in the lamp current Ibj. FIG. 5 (c)
Is increased as shown by the oblique line (φj). Incidentally, applying the timing of the drive signal to the switching element QA is as early in the rebound period t _2, the lamp current Ibj shown without increasing the input to the lighting device deliberately with diagonal lines can be effectively increased.

In this lighting device, the constant power circuit PS
The constant power of the input side of the high-frequency voltage generating circuit HA by T is basically obtained by turning off the switching element QA every time the drain current Ip flowing when the switching element QA is turned on reaches a preset value. It is done by doing. Here, the inductance of the primary coil TRa of the output transformer TRA is Lp, the drain current is Ip,
Assuming that the switching frequency is f, the power P on the input side is
P = 0.5Lp · Ip ² · f This power P depends on the drain current Ip and the switching frequency f because the inductance Lp of the primary coil TRa of the output transformer TRA is almost constant.
Therefore, in the constant power circuit PST, even if the voltage V _IN of the DC power supply EB fluctuates and the drain current changes as shown by a solid line, a dotted line, and a two-dot chain line in FIG. P is controlled to be substantially constant.

For example, when the DC power supply EB is at a normal voltage, the drain current Ip flows as shown by a solid line in FIG. 6A, and a preset value (Ip · R ₁ = Vref)
, The driving signal (gate signal) shown in FIG. 4B is applied to the switching element QA. As a result, the switching element QA is turned off at the time T, so that the power P (= 0. 5Lp · Ip ² · f) is kept constant. When the DC power supply EB becomes high, the drain current Ip ₁ is set at the time T ₁ earlier than the time T (Ip ₁ · R ₁ = V ₁ ) as shown by the dotted line in FIG.
ref) reached, the switching element QA shortened gate of the on-period as shown in the diagram (c) at this time - a result of bets signal is applied, the switching element QA is turned off at T ₁ time . Thus, the energy per cycle - the amount (0.5Lp · Ip ₁ ²⁾ T in FIG. (A)
Becomes equivalent to the case where the OFF state at the time, to the switching frequency f ₁ is higher than f, resulting in power ^{_{P (= 0.5Lp · Ip 1 2}} · f 1) is f becomes higher Just higher by the minute. Conversely, when the DC power supply EB becomes low, the drain current Ip ₂ becomes the set value (I ₂₎ at the time T ₂ which is later than the time T as shown by the two-dot chain line in FIG.
(p ₂ · R ₁ = Vref), and at this point, the switching element QA is provided with a gate signal whose ON period has been extended as shown in FIG.
A is turned off at T ₂ time. Thus, one cycle per energy - amount (0.5Lp · Ip _{² 2)} is made equal to the case of the OFF state at the time point T in FIG. (A), in order to switching frequency f ₂ is lower than f , resulting in power ^{_{P (= 0.5Lp · Ip 2 2}} · f 2)
Becomes lower by an amount corresponding to the decrease in f.

The phase advance circuit 40 in the above-mentioned constant power circuit PST is a circuit for correcting a signal delay in the circuit such as the drive circuit 20A, and operates as follows. When the switching element QA is turned on, the drain current Ip flows through the primary coil TRa of the output transformer TRA and the current detection circuit 30, as indicated by the solid line in FIG. The output voltage of the current detection circuit 30 is applied to the inverting input terminal of the operational amplifier OP in the comparison circuit 50 via the phase advance circuit 40, and is compared with the reference voltage Vref. At the time T, the drain current is set to a preset value (Ip · R ₁ = V
ref), the output of the operational amplifier OP becomes high level, and the output of the drive circuit 20A becomes low level.
At the time, the gate signal shown by the solid line is turned off. Therefore, the switching element QA is turned off at the time point T.

However, even if the comparison circuit 50 determines that the output voltage of the current detection circuit 30 has exceeded the reference voltage Vref at the time point T, the determination result is immediately applied to the switching element QA even if it is applied to the drive circuit 20A. The application of the gate signal is not stopped. That is, since a certain processing time is required until a predetermined signal is output based on the signal applied to the drive circuit 20A, the application of the gate signal to the switching element QA is actually stopped. As shown by the dotted line in FIG. 3B, the time Td is later than the time T by the time Td. For this reason, the drain current Ip flowing through the current detection circuit 30 is set to a predetermined value (Ip · R ₁ =
Vref), and the constant power function is hindered. Therefore, such a time lag is corrected based on the phase advance feature according to the capacitor C ₁ in the phase-advancing circuit 40. Furthermore, the phase advance capacitor function C ₁ is also serve to suppress the change in frequency due to the change of the aforementioned DC power source EB.

According to this embodiment, the high-frequency voltage generating circuit HA includes a constant power circuit P including the switching element QA connected in series to the primary coil TRa of the output transformer TRA.
Since the ST is incorporated, the high-frequency voltage generation circuit H
The power on the input side of A can be controlled to be substantially constant without being affected by the voltage fluctuation of the DC power supply. Therefore, the rare gas discharge lamp D
The light amount of L can be stabilized.

In the lighting state of the rare gas discharge lamp DL, the output transformer T
It is set within the first cycle of the free oscillation of the lamp current generated by the effective inductance on the secondary coil TRc side of RA and the effective capacitance when the rare gas discharge lamp DL is turned on. Since the constant period is set by the capacitor C ₂ and the resistor R ₆ of the drive circuit 20A, the off period (time from when the switching element QA is turned off to when it is turned on again) can be always constant. . Therefore, the time when the brightness (light amount) increases due to the increase in the lamp current becomes constant, and stable brightness with little fluctuation can be obtained.

[0037] In particular, the off period of the switching element QA, it is set to bounce period t ₂ the direction of the lamp current reverses, without increasing the input current of the high frequency voltage generating circuit HA to deliberately bounce period t ₂ Can be increased by Ibj, and accordingly, the brightness (light amount) φ can be increased by φj. Therefore, not only can the light amount of the rare gas discharge lamp DL be increased, but also the efficiency of the lighting device can be increased, and for example, it is possible to cope with an increase in the document feed speed in the OA equipment.

Further, since the phase advance circuit 40 including the capacitor C ₁ and the resistors R ₂ and R ₃ is connected between the current detection circuit 30 and the inverting input terminal of the operational amplifier OP in the comparison circuit 50, the drive is performed. Even if a signal delay occurs in a circuit such as the circuit 20A, the switching element QA can be turned off at an appropriate timing, and a desired constant power function can be achieved.

In the rare gas discharge lamp DL, triangular irregular portions 5A, 6A are formed at the side edges 5b, 6b of the external electrodes 5, 6 forming the second opening 8 so as to have a periodicity. Therefore, when a pulsed high-frequency voltage is applied to the external electrodes 5 and 6 from the high-frequency voltage generating circuit HA, the electric field concentrates on the apexes of the triangular portions in the deformed portions 5A and 6A, and the electric field concentrates through the rare gas space. Discharge easily between external electrodes.
Therefore, even if the voltage applied to the external electrodes 5 and 6 is slightly reduced due to the fluctuation of the power supply, the lighting can be reliably performed, and the occurrence of flicker can be suppressed. In particular, since the external electrode 6 on which the deformed portion 6A is formed is grounded in the state of being incorporated in the lighting device, the stability of the discharge state can be improved in combination with the formation of the deformed portion, and flickering occurs. Can be effectively suppressed.

In addition, the thickness of the envelope 1 in the rare gas discharge lamp DL is set in the range of 0.2 to 0.7 mm, and when a high frequency high voltage is applied to the external electrodes 5 and 6, In the thick range, flickering is likely to occur due to an increase in voltage distribution to the envelope itself due to an increase in the resistance component. However, as described above, the deformed portions 5A and 6A are formed on the external electrodes 5 and 6.
Is formed and the external electrode 6 is grounded, which effectively suppresses the occurrence of flickering even in a thick region, and the first opening portion is formed through the aperture portion 2a. 7 can also be effectively improved.

In particular, when the pressure of the noble gas is increased, the light output increases, but the starting characteristics are impaired. However, the triangular irregular portions 5A are formed on the side edges 5b, 6b of the external electrodes 5, 6. , 6A, even if the upper limit of the noble gas charging pressure is increased to 200 Torr, practically usable starting characteristics can be secured, and the generation of moving stripes (flickering) can be effectively suppressed. In addition, the light output can be effectively improved.
Therefore, when the present invention is applied to a document irradiating apparatus, a stable discharge state can be obtained and the illuminance of the document surface can be increased, so that an improvement in reading quality can be expected.

Further, the amount of the light emitting layer 2 deposited is 5 per cm ^2.
If the thickness is set in the range of 30 mg to 30 mg, the thickness of the envelope 1 is set to 0.
The light emitted from the first opening 7 through the aperture 2a in combination with the setting of the range of 2 to 0.7 mm and the setting of the rare gas filling pressure of 83 to 200 torr. Output can be increased effectively.

The amount of the light emitting layer 2 attached is set to be about 2 to 10 times that of a normal fluorescent lamp for illumination.
The light output of the rare gas discharge lamp has been effectively increased, though the amount is considered to be unfavorable in terms of characteristics in a normal fluorescent lamp for illumination. Although the cause is not clear, a stripe-shaped stripe is formed by forming an infinite number of discharge paths in the rare gas space between the external electrodes 5 and 6 (in a direction substantially perpendicular to the longitudinal direction of the envelope 1). This is considered to be a phenomenon peculiar to the rare gas discharge lamp that is lit in the state.

Further, the thickness of the envelope 1 and the structure of the external electrodes, preferably the adhesion amount of the light emitting layer 2 and the sealing pressure of the rare gas are set within the above-mentioned ranges, and then the first opening portion is formed. by setting 7 for the opening angle theta ₁ to the range of 60 to 90 °, increasing to more light output emitted from the first opening 7 I lighting coupled with due to the application of the pulsed high frequency, high voltage be able to. At this time, the separation length of the second opening 8 (the deformed portion 5
If the distance between the tips of A and 6A) is set to about 2 mm,
Leakage of light from the second opening 8 is suppressed, and a further improvement in the light output emitted from the first opening 7 can be expected.

FIG. 8 shows a second embodiment of the present invention. The basic structure is the same as that of the rare gas discharge lamp lighting device shown in FIG. The difference is that a distribution voltage from the DC power supply EB is applied to the output terminal of the phase advance circuit 40 as a bias voltage. Between the (inverting input terminal of the operational amplifier OP in the comparison circuit 50) output terminal of specifically DC power source EB and the fast circuit 40 Zener - diode - the series circuit of the de ZD ₁ and the resistor R ₇ is connected ing.

The operation of this lighting device is basically the same as that of the lighting device shown in FIG. 1, and different points will be described.
The primary current (drain current Ip) flows through the primary coil TRa of the output transformer TRA and the current detection circuit 30 by the ON operation of the switching element QA, and the current detection circuit 30
Causes a voltage drop due to the drain current Ip, which is applied to the comparison circuit 50 via the phase advance circuit 40. At this time, when the voltage of the DC power source EB is increased by the power fluctuation, the zener from a DC power source EB - diode - resistance through the de ZD ₁ R
_7, a current flows through the resistor R _3, the resistor R _7, divided voltage by the resistance ratio of the resistors R ₃ is added to the output voltage of the current detection circuit 30 as a bias. Therefore, the relative voltage difference between the output voltage applied to the comparison circuit 50 and the reference voltage Vref becomes small, and a slight increase in the output voltage causes the comparison circuit 50
Will operate.

According to this embodiment, by adding the distribution voltage of the DC power supply EB as a bias to the output voltage of the current detection circuit 30, the relative voltage difference between the output voltage of the current detection circuit 30 and the reference voltage Vref is obtained. Can be reduced, so that a function equivalent to substantially changing the reference voltage Vref of the comparison circuit 50 is achieved. Therefore, it is possible to appropriately control the switching operation of the switching element QA when the power supply fluctuates.

FIG. 9 shows a third embodiment of the present invention. The basic configuration is the same as that of the lighting device for a rare gas discharge lamp shown in FIG. The difference is that the connection point C between the primary coil TRa of the output transformer TRA and the switching element QA is different.
That is, the reference voltage dropping circuit 60 is connected to N, and the application of the reference voltage Vref to the non-inverting input terminal of the comparison circuit 50A is changed.

The reference voltage drop circuit 60 includes resistors R _{8 to} R
_14, a capacitor C _3, the transistor Q ₁ to Q _2,
Diode - the de D _1, Zener - diode - and a de ZD ₂ Prefecture. Specifically, a resistor R ₈ ,
R ₉ is connected in series, and a resistor R ₁₀
But of base transistor Q ₁ - it is connected to the scan. Voltage V _IN of the direct-current power supply EB to the collector of the transistor Q ₁
But the emitter resistor R ₁₁ and diode - the series circuit of the de D ₁ and capacitor C ₃ are connected. Diode - the output side of the de D ₁ Zener - diode - resistor R ₁₂ via the de ZD _2, R ₁₃ is connected, the resistor R ₁₃ is the base transistor Q ₂ - is connected to the scan. The collector of the transistor Q ₂ is the resistor R ₁₄ is connected, the emitter is grounded.

On the other hand, the comparison circuit 50A includes an operational amplifier OP
When, a resistor R ₄ to R ₅ for hysteresis resistor R ₁₅ to R
_16, Zener - diode - and a de ZD ₃ Prefecture. Specifically, the inverting input terminal (-) of the operational amplifier OP
To have been granted the output of the current detection circuit 30, the non-inverting input terminal (+) resistor R _4, the DC power source EB is connected via a series circuit of a resistor R ₁₅ to R _16. Then, the connection point between the resistor R ₁₅ and the resistor R ₁₆ Zener - diode - de Z
D ₃ is connected, the voltage of the connection point is always the Zener - diode - by de ZD ₃ zener - is maintained at a voltage, which acts as the reference voltage Vref. Also, the resistors R ₄ and R ₁₅
Is connected to a resistor R in the reference voltage drop circuit 60.
One end of ₁₄ is connected.

The operation of this lighting device is basically the same as that of the lighting device shown in FIG. The difference is that the reference voltage dropping circuit 60 operates only when the rare gas discharge lamp DL is not connected to the output side of the high-frequency voltage generating circuit HA2 or when the rare gas discharge lamp DL is not lit even if it is connected.
If it lights up normally, it will not work.
The reference voltage Vref applied to the comparison circuit 50A can be changed (dropped) in accordance with the operation of the reference voltage dropping circuit 60.

For example, when the high-frequency voltage generating circuit HA2 is operated in a no-load state in which the rare gas discharge lamp DL is not connected to the output side, the primary coil TRa of the output transformer TRA is related to the on / off operation of the switching element QA. Generates a high voltage Vd of (Na / Nc) · Vf. Here, Na and Nc are the primary coil TRa and the secondary coil TR
The number of windings c and Vf are voltages generated in the secondary coil TRc. This voltage Vd is divided by the resistance ratio between the resistor R ₈ and the resistor R _9, the base transistor Q ₁ via the resistor R ₁₀ - it is applied to the scan. Incidentally, the divided voltage when the transistor Q ₁ is silicon transistor, becomes about 0.6V, in the normal state where the high voltage Vd is not generated is set to be equal to or less than about 0.3V. Transistor Q ₁
When a voltage of about 0.6 V is applied to the transistor Q,
₁ is turned on, and the transistors Q ₁ ,
Current flows through the resistor R _11, the voltage to the resistor R ₁₁ (e.g., 2-4
(Approximately V). This voltage is the diode D ₁
Charged in the capacitor C ₃ through, this voltage Zener - diode - Zener de ZD ₂ - exceeds a voltage, resistance R
₁₂ Voltage (for example, a voltage of approximately 1 to 2 V) is generated, the resistance R ₁₃ via the transistor Q ₂ base - results that are applied to the scan, the transistor Q ₂ is turned ON. On the other hand, the non-inverting input terminal of the operational amplifier OP has a Zener diode ZD ₃
Zener - although the reference voltage Vref, which is determined by the voltage is applied, as described above, the resistor R ₁₅ by turning on the operating transistor Q _2, current flows through resistor R _14, the voltage drop across the resistor R ₁₅ Occurs. As a result, the Zener diode ZD ₃ is connected to the non-inverting input terminal of the operational amplifier OP.
Zener - much lower voltage obtained by subtracting the voltage drop of the resistor R ₁₅ is from the voltage will be applied as the reference voltage.
Therefore, although the output voltage of the current detection circuit 30 is compared with the reference voltage whose voltage has dropped, a high-level signal is immediately output from the comparison circuit 50A, and a gate signal is applied to the switching element QA from the drive circuit 20A. Switching element QA is turned off.
For this reason, the high voltage Vd induced from the secondary coil TRc of the output transformer TRA to the primary coil TRa is eliminated, and the destruction of the switching element QA can be avoided.

According to this embodiment, since the reference voltage dropping circuit 60 is added to the high frequency voltage generating circuit HA2 in addition to the constant power circuit PST1, the high frequency voltage generating circuit H2
Even if the rare gas discharge lamp DL is not connected to the output side of A2 or does not light up even if it is connected, the reference voltage dropping circuit 60 and the comparison circuit 50A immediately lower the reference voltage. By
Undesirably high voltage Vd generated in primary coil TRa of output transformer TRA is suppressed. Therefore, the destruction of the switching element QA can be prevented.

FIGS. 10 to 11 show a fourth embodiment of the present invention. The basic structure is the same as that of the rare gas discharge lamp DL shown in FIGS. The difference is that a triangular irregular portion 6A is formed only on the side edge 6b of the external electrode 6, and the other side edges 5a, 6b of the external electrode 5 and the side edge 6a of the external electrode 6 are all stray. That is, it is formed in the shape of a triangle.
The irregularly shaped portion 6A may be formed in a semicircular shape, a rectangular shape, or the like, in addition to the triangular shape.

In particular, the rare gas discharge lamp DL having this structure is shown in FIG.
When incorporated in the lighting device shown in FIG. 8 or FIG. 9, if all the external electrodes are lighted in a floating state, the discharge is performed even if the power supply line is maintained at the rated voltage. It is unstable, a striped discharge state may be visually observed, and flicker may occur. However, as shown in FIG. 1, by grounding the external electrode 6 on the side where the deformed portion 6A is formed, if the power supply voltage becomes 1
Even if it is reduced by about 0%, a stable discharge state in which flicker is suppressed can be obtained.

According to this embodiment, the external electrodes 5, 6
When a pulsed high-frequency voltage is applied to the side edge portion 6b
A discharge is generated between the deformed portion 6A and the straight side edge 5b, but one side edge (5b) is straddled.
Since they are formed in the shape of a triangle, there is no need to adjust the pitch (position alignment) of the two, and the ease of assembly can be improved.

FIG. 12 shows a fifth embodiment of the present invention. The basic configuration is the same as that of the rare gas discharge lamp shown in FIGS. The lighting device incorporating the rare gas discharge lamp DL may be the lighting device of the rare gas discharge lamp shown in FIGS. 8 and 9 in addition to FIG. The difference is that the side edges 5b and 6b of the external electrodes 5 and 6 have a central portion (for example, 20 to 70% of the total length, preferably 30 to 5
(0% range), triangular shaped portions 5A and 6A are formed, and the other side edges of the external electrodes are all formed in a straight shape. Note that the external electrode 6 is grounded.

According to this embodiment, the same effects as those of the above-described embodiment can be obtained, and the area of the central portion of the external electrodes 5 and 6 as the electrode is reduced by forming the deformed portions 5A and 6A. In addition, the current density at the time of lighting decreases,
The temperature difference between the central portion and the end of the envelope 1 in the axial direction is reduced. Therefore, it is possible to approximate the attenuation of the illuminance generated from the initial lighting to the stable state, and to improve the direction of uniforming the illuminance distribution in the axial direction.

Further, the deformed portions 5A, 5A,
Although the formation area of 6A is smaller than that of the first and fourth embodiments, similar starting characteristics are obtained,
Discharge similar to that of the deformed portion is generated in the portion where A and 6A are not formed, and a stable discharge state is obtained.

FIG. 13 shows a sixth embodiment of the present invention. The basic configuration is the same as that of the rare gas discharge lamp shown in FIG. The lighting device incorporating the rare gas discharge lamp DL may be the lighting device of the rare gas discharge lamp shown in FIGS. 8 and 9 in addition to FIG. The difference is that the deformed portion 6A at the side edge portion 6b of the external electrode 6 is omitted, and the external electrode 6 is formed in a straight shape.

FIG. 14 shows a seventh embodiment of the present invention. The basic structure is the same as that of the rare gas discharge lamp shown in FIGS. The lighting device incorporating the rare gas discharge lamp DL may be the lighting device of the rare gas discharge lamp shown in FIGS. 8 and 9 in addition to FIG. The difference is that external electrodes 5 and 6 having deformed portions 5A and 6A on the outer peripheral surface of envelope 1 are provided.
The first and second openings 7 and 8 are separated from each other so as to be formed, and a light-transmitting seal is provided on the outer peripheral surface of the envelope 1.
4A is wound and attached so that the attached external electrodes 5 and 6 are covered. In addition, this translucent sheet 4
An adhesive layer is formed on one surface of A and is adhered by winding.

FIG. 15 shows an eighth embodiment of the present invention, and the basic configuration is the same as that of the rare gas discharge lamp shown in FIGS. The difference is that external electrodes 5 and 6 having deformed portions 5A and 6A are attached to the outer peripheral surface of the envelope 1 so as to be separated from each other so that first and second openings 7 and 8 are formed. Later, a protective tube 12 made of a heat-shrinkable resin was attached to the outer peripheral surface of the envelope 1 so as to cover the external electrodes 5 and 6 attached thereto, and the heat-shrinkable resin was brought into close contact. . The protective tube 12 is preferably made of, for example, a PET resin to which heat shrinkage has been imparted.
Heating to about 200 ° C. causes thermal contraction and close contact with the envelope 1.

According to this embodiment, since there is no overlapped portion on the translucent sheet (insulating member for exterior) as in the above-described embodiments, it can be used under any conditions. In addition, the protection tube 12 is not peeled off from the envelope 1, so that the exposure of the external electrodes 5 and 6 can be surely prevented, and the safety can be expected to be improved.

It should be noted that the present invention is not limited to the above-described embodiment. For example, a phase advance circuit connected between the current detection circuit and the comparison circuit may be omitted depending on the required accuracy of the lighting device. it can. Also, if the drive circuit can apply a drive signal having a constant off period to the switching element,
Circuit elements other than the monostable multivibrator can be applied. The reference voltage drop circuit is not limited to the circuit shown in the drawing as long as a substantial no-load on the output side of the high-frequency voltage generating circuit can be quickly avoided. In particular, it is most desirable that the off period of the switching element be set within the rebound period of the lamp current. However, either the first period of free oscillation or the end of the rebound period from the first peak point. Can also be set to Further, in the rare gas discharge lamp incorporated in the lighting device, the light emitting layer thereof can be formed on the entire inner surface of the envelope by omitting the aperture portion. In addition, the pitch, height, etc. of the deformed portion of the external electrode can be changed as appropriate according to the size of the rare gas discharge lamp. The grounding of the external electrode having the deformed portion can be omitted. It can be omitted. Further, in the form of the external electrode, the term "strip" means that the overall form is a strip, and includes those in which a deformed portion, a hole, or the like exists in a side edge portion or a portion other than the side edge portion. And

[0065]

Next, an experimental example will be described. First, a europium-activated barium magnesium aluminate phosphor having an emission spectrum in the blue region, a cerium / terbium-activated lanthanum phosphate phosphor having an emission spectrum in the green region, and europium having an emission spectrum in the red region. A water-soluble phosphor coating solution obtained by mixing activated yttrium and gadolinium borate phosphors at a ratio of 65, 15, and 20% by weight, respectively, is used to form an envelope made of lead glass having an outer diameter of 8 mm and a length of 300 mm. It is applied on the inner surface to form a light emitting layer. Next, an aperture having an opening angle of 75 ° is formed by forcibly peeling off a part of the light emitting layer using a scraper. Note that the amount of the light emitting layer attached is 12 mg / cm ² .
Next, the envelope is sealed by a top seal method, and xenon gas is sealed in the internal space at a pressure of 120 torr. Thereafter, a sheet structure is wound around the outer peripheral surface of the envelope, and FIG.
A rare gas discharge lamp having the structure shown in FIG. 11 was manufactured. An aluminum foil having a width of 8 mm is used for the pair of external electrodes, and only one side edge of the external electrode forming the second opening has a triangular shape having a pitch of 4 mm and an apex height of 1.5 mm. And the other opposing side edge was formed in a straight shape.

This rare gas discharge lamp is incorporated in the lighting circuit shown in FIG. 1, the external electrode having the deformed portion is grounded, and the off period of the switching element in the high-frequency voltage generating circuit is set to the first half of the rebound period of the lamp current. At the same time, the output voltage of the high-frequency voltage generating circuit is changed to a rated value (frequency is 30 KH
At z, the pulse voltage is set to 2000 V _0-P ) to turn on the rare gas discharge lamp, and 8 mm from the center of the rare gas discharge lamp.
When illuminance was measured by arranging an illuminometer in a remote place,
38000 Lx, and the input current of the high-frequency voltage generation circuit was 620 mA. In the case where the off period of the switching element is delayed outside the rebound period, 38000 Lx
The input current had to be increased to 790 mA in order to obtain an illuminance of. Therefore, in the device of the present invention, the illuminance can be further increased by increasing the input current to 790 mA. In addition, no flicker occurred in the lighting state, and a stable discharge state was observed.

[0067]

As described above, according to the present invention, since the high-frequency voltage generating circuit incorporates the constant power circuit including the switching element connected in series to the primary coil of the output transformer, the high-frequency voltage generating circuit The power on the input side of the circuit can be controlled substantially constant without being affected by power supply fluctuations. Therefore, the light quantity of the rare gas discharge lamp can be stabilized.

When the rare gas discharge lamp is turned on, the lamp current generated by the effective inductance on the secondary coil side of the output transformer and the effective capacitance when the rare gas discharge lamp is turned on during the off period of the switching element. Is set within the first one cycle of the free vibration of the switching element, and the length thereof is set to be substantially constant, so that the timing at which the switching element is turned off and then turned on again can be always constant. . Therefore, the time when the brightness (light amount) increases due to the increase in the lamp current becomes constant, and stable brightness with little fluctuation can be obtained.

In particular, if the off period of the switching element is set within the rebound period in which the direction of the lamp current is reversed, the lamp current flowing during the rebound period can be reduced without further increasing the input current of the high-frequency voltage generating circuit. The amount of light can be effectively increased, and accordingly, the amount of light can be increased in accordance with the amount of current increase. Therefore, not only can the amount of light of the rare gas discharge lamp be increased, but also the efficiency of the lighting device can be increased, and for example, it is possible to cope with an increase in the document feeding speed in the OA equipment.

If a phase advance circuit including a capacitor is connected between the current detection circuit and the comparison circuit, the switching element is turned off at an appropriate timing even if a signal delay occurs in a circuit such as a drive circuit. And a desired constant power function can be achieved.

Further, if a deformed portion is formed at one of the side edges of the external electrode forming the second opening in the rare gas discharge lamp, a pulsed high-frequency voltage is applied from the high-frequency voltage generating circuit to the external electrode. When the voltage is applied, the electric field concentrates on the deformed portion, and the discharge easily occurs between the external electrodes through the rare gas space.
Therefore, even if the voltage applied to the external electrode slightly decreases due to the power supply fluctuation, it is possible to light the lamp reliably, and
The generation of flicker can also be suppressed. In particular, when the external electrode having the irregular shape is grounded in the state of being incorporated into the lighting device, the stability of the discharge state can be improved in conjunction with the formation of the irregular shape, and the occurrence of flicker can be effectively suppressed. it can.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of the rare gas discharge lamp shown in FIG.

FIG. 3 is a development view of an envelope and external electrodes of the rare gas discharge lamp shown in FIG. 2;

FIG. 4 is an operation explanatory diagram of FIG. 1, wherein FIG.
FIG. 2B is a waveform diagram of a drain current flowing through the switching element, FIG. 2C is a waveform diagram of a lamp current, and FIG. 2D is a light emission waveform diagram.

5A and 5B are enlarged views showing a relationship between a lamp current and a drive timing of a switching element, wherein FIG. 5A is a waveform chart of a lamp current, and FIG. 5B is a waveform chart of a gate signal; FIG. 3C is a light emission waveform diagram.

6A and 6B are explanatory diagrams of the operation of the constant power circuit shown in FIG. 1, wherein FIG. 6A is a waveform diagram of first to third drain currents,
FIG. 4B is a waveform diagram of a gate signal corresponding to the first drain current, FIG. 4C is a waveform diagram of a gate signal corresponding to the second drain current, and FIG. FIG. 9 is a waveform chart of a gate signal corresponding to a third drain current.

7A and 7B are explanatory diagrams of the operation of the phase advance circuit in the constant power circuit shown in FIG. 1, wherein FIG. 7A is a waveform diagram of a drain current, and FIG. 7B is a gate corresponding to the drain current. FIG.

FIG. 8 is an electric circuit diagram of a lighting device showing a second embodiment of the present invention.

FIG. 9 is an electric circuit diagram of a lighting device according to a third embodiment of the present invention.

FIG. 10 is a longitudinal sectional view showing a fourth embodiment of the present invention.

11 is an exploded view of an envelope and external electrodes of the rare gas discharge lamp shown in FIG.

FIG. 12 is a development view of an envelope and external electrodes of a rare gas discharge lamp showing a fifth embodiment of the present invention.

FIG. 13 is a development view of an envelope and an external electrode of a rare gas discharge lamp showing a sixth embodiment of the present invention.

FIG. 14 is a longitudinal sectional view showing a seventh embodiment of the present invention.

FIG. 15 is a longitudinal sectional view showing an eighth embodiment of the present invention.

FIG. 16 is a longitudinal sectional view of a rare gas discharge lamp according to the prior art.

FIG. 17 is a development view of a sheet structure according to the prior art.

FIG. 18 is a sectional view taken along line XX of FIG. 17;

FIG. 19 is a longitudinal sectional view for explaining a method for manufacturing a rare gas discharge lamp according to the prior art.

FIG. 20 is an electric circuit diagram of a rare gas discharge lamp lighting device according to the prior art.

[Explanation of symbols]

Reference Signs List 1 envelope 2 light emitting layer 2a aperture 3 sheet structure 4, 4A translucent sheet (insulating member) 5, 6 external electrode 5a, 5b, 6a, 6b side edge 5A, 6A irregular shape Reference Signs List 7 first opening 8 second opening 12 protection tube (insulating member) 20A drive circuit 30 current detection circuit (resistance) 40 phase advance circuit 50, 50A comparison circuit 60 reference voltage drop circuit DL rare gas discharge lamp HA, HA1, HA2 high frequency voltage generating circuit TRA output transformer TRa primary coil TRc secondary coil QA switching element CA capacitors PST, PST1 constant power circuit OP operational amplifier M monostable multivibrator - data R ₁ to R ₁₆ resistor C ₁ -C ₃ capacitor ZD ₁ ~ZD ₃ zener - diode - de Q ₁ ~Q ₂ transistor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA01 AA19 BA03 BB01 EB01 EB06 GA02 GB04 GC04 HB03

Claims (12)

[Claims] 1. A pair of band-shaped external electrodes made of a metal member are formed on the outer peripheral surface of an envelope having a light emitting layer on the inner surface, and first and second openings are formed over substantially the entire length of the envelope. And a constant-power circuit including a switching element on the input side of the output transformer, and the output is performed based on the switching operation of the switching element by applying and stopping the drive signal. A high-frequency voltage generating circuit for generating a pulsed high-frequency voltage on the output side of the transformer, wherein the rare gas discharge lamp is provided on the output side of the high-frequency voltage generating circuit, and a pulsed high-frequency voltage is applied to a pair of external electrodes. Characterized in that the power on the input side of the high-frequency voltage generation circuit in the lighting state of the rare gas discharge lamp is controlled to be substantially constant by a constant power circuit. Lighting device. 2. A pair of band-shaped external electrodes made of a metal member are formed on the outer peripheral surface of an envelope having a light emitting layer on the inner surface, and first and second openings are formed over substantially the entire length of the envelope. And a rare gas discharge lamp in which a translucent insulating member is mounted on the outer peripheral surface of the envelope so that the external electrodes are covered, and on the input side of the output transformer. A high-frequency voltage generating circuit that generates a pulsed high-frequency voltage on the output side of an output transformer based on a switching operation of the switching element by applying / stopping a drive signal, A rare gas discharge lamp is connected to the output side of the high-frequency voltage generation circuit so that a pulsed high-frequency voltage is applied to a pair of external electrodes, and the input side of the high-frequency voltage generation circuit when the rare gas discharge lamp is turned on. Power, constant power A lighting device for a rare gas discharge lamp, wherein the lighting device is controlled so as to be substantially constant by a conversion circuit. 3. The rare gas discharge lamp according to claim 1, wherein the light emitted from the light emitting layer is mainly emitted to the outside from the first opening, and at least one of the side edges of the external electrode has a deformed portion. 3. The method according to claim 1, wherein
The lighting device for a rare gas discharge lamp according to claim 1. 4. The rare gas discharge lamp according to claim 2, wherein in the rare gas discharge lamp, the insulating member is formed of a protective tube made of a translucent sheet or a heat-shrinkable resin. Lighting device for electric lights. 5. The high-frequency voltage generating circuit includes at least an output transformer having primary and secondary coils, a constant power circuit including a switching element connected in series to the primary coil of the output transformer, and a primary coil of the output transformer. 3. The lighting device for a rare gas discharge lamp according to claim 1, wherein the lighting device comprises a capacitor connected in parallel with a series circuit with a constant power circuit. 6. The constant power circuit includes at least a switching element connected in series to a primary coil of an output transformer, a current detection circuit connected in series to the switching element,
A comparison circuit for comparing an output voltage corresponding to the current detected by the current detection circuit with a reference voltage, and a switching element based on a signal output when the output voltage of the current detection circuit is higher than the reference voltage in the comparison circuit 3. A rare gas discharge lamp according to claim 1, further comprising: a drive circuit for outputting a drive signal for turning on the switching element after a predetermined period of time after turning off the device. apparatus. 7. The constant power circuit includes at least a switching element connected in series to a primary coil of an output transformer, a current detection circuit connected in series to the switching element,
A comparison circuit for comparing an output voltage corresponding to the current detected by the current detection circuit with a reference voltage; a phase advance circuit including a capacitor and a resistor connected between the current detection circuit and the comparison circuit; A drive circuit for outputting a drive signal for turning on the switching element after a predetermined period of time after turning off the switching element based on a signal output when the output voltage of the detection circuit becomes higher than the reference voltage; The lighting device for a rare gas discharge lamp according to claim 1 or 2, wherein a delay of a signal in a comparison circuit, a drive circuit, or the like is corrected by a phase advance circuit. 8. The rare gas discharge according to claim 6, wherein the drive circuit for applying a drive signal for keeping the off period of the switching element constant is constituted by a monostable multivibrator. Lighting device for electric lights. 9. The first period of the free oscillation of the lamp current generated by the effective inductance on the secondary coil side of the output transformer and the effective capacitance when the rare gas discharge lamp is turned on is the off period of the switching element. 9. The lighting of a rare gas discharge lamp according to claim 6, wherein the setting is made within a period, preferably during a rebound period in which the lamp current reverses from the first peak point of the free oscillation. apparatus. 10. The comparison circuit of the constant power circuit is mainly constituted by an operational amplifier, and a reference voltage is applied to a non-inverting input terminal of the operational amplifier, and an output voltage of the current detecting circuit is applied to an inverting input terminal of the operational amplifier. The lighting device for a rare gas discharge lamp according to claim 6 or 7, wherein: 11. The lighting device for a rare gas discharge lamp according to claim 10, wherein a distribution voltage of a power supply voltage is applied as a bias voltage to an inverting input terminal of an operational amplifier in the constant power circuit. 12. An output transformer having primary and secondary coils, a switching element connected in series to the primary coil of the output transformer, a current detection circuit connected in series to the switching element, and a current detected by the current detection circuit. A comparison circuit composed of an operational amplifier for comparing the output voltage with a reference voltage. In the comparison circuit, the switching element is turned off based on a signal output when the output voltage of the current detection circuit becomes higher than the reference voltage, and is set in advance. A high-frequency voltage generating circuit including a driving circuit for outputting a driving signal for turning on the switching element after a given period of time, and a high-frequency voltage generating circuit connected to the output side of the high-frequency voltage generating circuit and having a light emitting layer on the inner surface. A pair of band-shaped external electrodes made of a metal member are provided on the outer peripheral surface of the envelope over the substantially entire length of the envelope. It is detected that the back electromotive force voltage generated in the primary coil of the rare gas discharge lamp and the primary coil of the output transformer, which are arranged apart from each other so that two openings are formed, exceeds a predetermined value. A lighting device for a rare gas discharge lamp, comprising: a reference voltage drop circuit that drops a reference voltage applied to a comparison circuit based on a detection result.