JP2002164186A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide good starting regardless of existence of adjoining conductors. SOLUTION: This is a lighting device of discharge lamp that is equipped with a bulb 1, an induction coil 2, a high frequency power supply circuit 2, and a matching circuit 4. The matching circuit 4 is a single circuit that has a first passive element 4a connected in series to the induction coil and a second passive element 4b connected in parallel to the series circuit of the induction coil 2 and the passive element 4a. The induction coil 2 and the passive elements 4a, 4b constitute a resonant loop, and the passive elements 4a, 4b are set so as to generate a high starting voltage at the both ends of the induction coil 2 by resonance in the resonant loop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device. More particularly, the present invention relates to a discharge lamp lighting device that emits light from a sealed substance by generating plasma discharge in a bulb by an induction coil provided near the bulb.

[0002]

2. Description of the Related Art Conventional discharge lamp lighting devices include, for example,
It is disclosed in Japanese Utility Model Laid-Open No. 5-20297. FIG. 13 shows the configuration of a discharge lamp lighting device (electrodeless discharge lamp lighting device) disclosed in this publication.

[0003] The lighting device shown in FIG. 13 includes a bulb 1 in which a discharge gas such as an inert gas or metal vapor is sealed in a light-transmitting bulb, and an induction coil 2 disposed near the bulb 1.
And a high-frequency power supply circuit 3 for supplying high-frequency power to the induction coil 2, and a matching circuit 4 for matching the impedance of the induction coil 2 and the high-frequency power supply circuit 3 and transmitting the high-frequency power to the valve 1 efficiently. ing. In this lighting device, the high frequency power supply circuit 3 applies several tens
By passing a high frequency current from Hz to several hundred MHz,
A plasma discharge can be generated inside the bulb 1,
It can emit ultraviolet light or visible light.

During the operation of the lighting device, the impedance seen from the high-frequency power supply circuit 3 changes drastically due to the start of discharge or the change with time of discharge, and the matching circuit 4 may not be able to match. In such a case, there is a possibility that the lamp will not be turned on, or an overcurrent will flow through the circuit element to destroy the circuit element. Therefore, there is a problem that the single matching circuit 4 cannot perform the matching well, and the discharge cannot be started, or the transition from the glow discharge to the arc discharge cannot be performed, resulting in poor starting. In order to solve such a problem, in the lighting device shown in FIG. 13, the matching circuit 4 is composed of the starting matching circuit 41 and the lighting matching circuit 42, and the switching means SW1 to SW4 are provided. The operation is as follows.

First, when the high frequency power generated by the high frequency power supply circuit 3 is supplied to the inside of the valve 1, the switching means S
W1 to SW4 act to contact the respective contacts a and c.
Are short-circuited, and the starting matching circuit 41 is connected between the high-frequency power supply circuit 3 and the induction coil 2. The starting matching circuit 41 is designed so as to realize an optimum matching state with respect to the impedance of the induction coil 2 when no discharge is generated in the bulb 1, and the induction coil 2 is efficiently supplied with a high frequency wave by the operation described above. Electric power is supplied, and the discharge to the bulb 1 can be reliably started by the high-frequency electromagnetic field generated from the induction coil 2.

Next, when the discharge starts, the switching means SW1
In addition, the respective contacts b and c are short-circuited by the action of SW4, and the state in which the starting matching circuit 41 is connected is switched to the state in which the lighting matching circuit 42 is connected. The lighting matching circuit 42 is designed so as to realize an optimum matching state in a stable lighting state, and is configured such that the above-described switching stably maintains the discharge.

[0007]

However, the cause of the change in the matching state is not limited to the presence or absence of the discharge plasma. For example, there is a phenomenon in which the inductance of the induction coil 2 largely fluctuates due to the influence of a nearby conductor such as a reflector of a lighting fixture, and the matching state changes, which leads to poor starting of the lamp.

In the above configuration, since the induction coil 2 has an open magnetic path in which the magnetic path is opened, if a nearby conductor is present, the impedance of the magnetic circuit formed by the induction coil 2 greatly varies. Become. Generally, it is known that the presence of the proximity conductor reduces the inductance of the induction coil 2 and increases the resistance component. Therefore, when the proximity conductor is present, the proximity conductor and the induction coil 2
The inductance has a large fluctuation range depending on the distance between the two and the positional relationship between the two.

When there are only two types of states, that is, a state before starting and a state after lighting, there is little problem with the simple switching of the matching circuit 4 as shown in FIG. In the case where there are many states depending on the positional relationship with the adjacent conductor, the configuration shown in FIG.

The general matching circuit 4 considers only the impedance matching at the time of starting or lighting when no adjacent conductor exists. For this reason, when the inductance of the induction coil 2 decreases due to the presence of the proximity conductor, the resonance frequency in the resonance loop including the induction coil 2 and the operating frequency of the high-frequency power supply circuit 3 are far apart, and both ends of the induction coil 2 However, there is also a problem that a starting voltage that is much lower than that of the original design can be generated, which leads to poor starting.

The present invention has been made in view of the above points, and a main object of the present invention is to provide a discharge lamp lighting device capable of achieving good starting regardless of the presence or absence of a nearby conductor.

[0012]

A discharge lamp lighting device according to the present invention includes a bulb filled with a discharge gas, an induction coil provided near the bulb, and a high-frequency power supply circuit for supplying high-frequency power to the induction coil. And a matching circuit arranged between the high-frequency power supply circuit and the induction coil and performing impedance matching between the two, wherein the matching circuit is connected in series to the induction coil. A single passive circuit having a first passive element, and a second passive element connected in parallel to a series circuit of the induction coil and the first passive element, wherein the induction coil and the first passive element are connected in series. The passive element and the second passive element form a resonance loop, and include the first passive element and the second passive element.
Are set to generate a high starting voltage at both ends of the induction coil by resonance in the resonance loop.

[0013] The induction coil, the first passive element and the front
The resonance frequency f with the second passive element ₁And the high frequency power
Operating frequency f of the source circuit₀0.85f₀≤ f₁≤
0.97f₀So that the first passive element and
And the value of the second passive element is preferably selected.
New

The values of the first passive element and the second passive element are set such that the relation between the resonance frequency f ₁ and the operating frequency f ₀ satisfies 0.90f ₀ ≦ f ₁ ≦ 0.95f _0. Is preferably selected.

The resonance frequency f ₂ between the first passive element and the induction coil and the operating frequency f _{0 of the} high-frequency power supply circuit
It is preferable that the value of the first passive element is selected so that the relationship with the following satisfies 0.7f ₀ ≦ f ₂ ≦ 0.86f ₀ .

The resonance frequency f ₁ ′ of the induction coil, the first passive element, and the second passive element when the inductance of the induction coil decreases, and the lighting when the inductance of the induction coil decreases. The first passive element and the second passive element such that a possible relationship with an operating frequency f ₀ ′ of the high-frequency power supply circuit satisfies 0.95f ₀ ′ ≦ f ₁ ′ ≦ 0.97f ₀ ′ Is preferably selected.

In one embodiment, each of the first passive element and the second passive element is a capacitor.

It is preferable that the apparatus further comprises a variation means for varying the operating frequency of the high-frequency power supply circuit in accordance with a combined impedance of the matching circuit, the induction coil, and plasma generated in the bulb.

In one embodiment, the high-frequency power supply circuit operates at a frequency of 50 kHz or more and 500 kHz or less.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments. (Embodiment 1) A discharge lamp lighting device according to Embodiment 1 of the present invention will be described with reference to FIGS.

FIG. 1 shows a circuit configuration of the present embodiment. The discharge lamp lighting device according to the present embodiment is a discharge lamp lighting device (electrodeless discharge lamp lighting device) that emits a sealed substance by generating a plasma discharge in the bulb by an induction coil 2 provided near the bulb 1. FIG.
The discharge lamp lighting device having the circuit configuration shown in FIG. 1 includes a bulb 1 in which a discharge gas is sealed, an induction coil 2 provided in the vicinity of the bulb, a high-frequency power supply circuit 3 for supplying high-frequency power to the induction coil 2, High frequency power circuit 3 and induction coil 2
And a matching circuit 4 for performing impedance matching between the two (3 and 2).

The matching circuit 4 is a single circuit having a passive element 4a connected in series to the induction coil 2 and a passive element 4b connected in parallel to a series circuit of the induction coil 2 and the passive element 4a. The induction coil 2, the passive element 4a, and the passive element 4b form a resonance loop. The passive elements 4a and 4b are set to generate a high starting voltage at both ends of the induction coil 2 by resonance in the resonance loop. Passive element 4a and passive element 4b
How to set is described later.

Next, the operation of the configuration shown in FIG. 1 will be described. First, the high-frequency power supply circuit 3 (for example, full bridge
High-frequency power generated by various inverter circuits such as an inverter and a half-bridge inverter is supplied to the induction coil 2 via the matching circuit 4. When high-frequency power is supplied to the induction coil 2, a high-frequency electromagnetic field is generated in a portion near the induction coil 2 inside the valve 1. The discharge gas inside the bulb 1 generates discharge plasma by the high-frequency electromagnetic field, and necessary visible light can be obtained by excitation and emission of the discharge gas.

In the configuration shown in FIG. 1, the matching circuit 4 is constituted by a single circuit and has no switching means.
For this reason, when the stable lighting is performed, the matching circuit 4 combines the impedance of the matching circuit 4, the induction coil 2, and the plasma inside the bulb 1 (hereinafter, sometimes referred to as a load impedance) and the impedance of the high-frequency power supply circuit 3. Are set so that impedance matching can be achieved.

A half-bridge power supply circuit 3
FIG. 2 shows a circuit configuration using an inverter. FIG.
The operation of the high frequency power supply circuit 3 shown in FIG.

The power supplied to the lighting device at the frequency of the commercial power supply is rectified into DC power by a rectifier circuit (not shown) inside the high-frequency power supply circuit 3, and this rectifier circuit
Works as The power supplied from the DC power supply 5 is supplied to the switching elements 6a and 6
By the switching operation of b, it is converted into a desired high-frequency AC power. This switching operation is performed by the oscillation circuit OSC
Is applied to the gates of the switching elements 6a and 6b via the transformer 7 via the switching signal generated by the oscillation of The generated high-frequency AC power is transmitted to the matching circuit 4 via the choke coil 8 and further applied to the discharge coil inside the induction coil 2 and the bulb 1.

Next, the relationship between the induction coil 2 and the bulb 1 in the discharge lamp lighting device of the present embodiment will be described with reference to FIG. FIG. 3 corresponds to an equivalent circuit of the configuration shown in FIG. 1 or FIG.

As shown in FIG. 3, the discharge plasma is replaced by a one-turn transformer secondary winding wound around the induction coil 2 and an impedance element (corresponding to plasma impedance). And the plasma impedance Z _pl converted to the induction coil side. As described above, the matching circuit 4 is designed using the equivalent circuit shown in FIG. 3 so as to achieve impedance matching in a stable lighting state. Impedance matching is
The real part and the imaginary part of the load impedance are adjusted to desired values. To realize this adjustment, it is sufficient that there are two components whose constants can be adjusted. However, FIG.
In the circuit shown in FIG. 2, there are three types of components that can be adjusted: the choke coil 8, the passive element 4 a, and the passive element 4 b, so that the degree of freedom is three. Therefore, in the circuit shown in FIG. The values of the two conditions of the real part and the imaginary part of the impedance are not uniquely determined.

Therefore, first, in the case where the proximity conductor does not exist near the bulb 1 of the lighting device shown in FIG. 1, sufficient discharge starting performance is obtained by resonance of the passive elements 4a, 4b and the induction coil 2. Is performed to clarify the conditions under which the condition can be secured. FIG. 4 shows the results.

In this embodiment, 1.5 Torr (200 Pa) of argon gas and 4 mg of mercury are sealed in the bulb 1 and a fluorescent material is applied to the inner wall of the bulb 1. The size of the valve 1 is 60 m in outer diameter.
m, a height of 65 mm, and a bulb 1 having a recess of 20 mm in diameter along the central axis of the bulb 1 was used. As the induction coil 2, a Mn—Zn-based ferrite core having an outer diameter of 14 mm and a litz wire wound around 66 turns is used, and the induction coil 2 is inserted into a concave portion of the bulb 1. The inductance of the induction coil 2 was 377 μH. Further, the oscillation frequency of the high-frequency power supply circuit 3 was adjusted from 80 kHz to 100 kHz to a frequency at which starting and lighting could be maintained. The passive element 4a or the passive element 4b can be configured using either a choke coil or a capacitor. However, since the choke coil has relatively large copper loss and iron loss, in the present embodiment, the passive elements 4a and 4b As a capacitor.

FIG. 4 shows the relationship between the value (pF) of the passive element 4a and the value (pF) of the passive element 4b that can achieve a good discharge start. The hatched area in FIG. 4 indicates that, when the impedance of the passive element 4a is adjusted so that starting and lighting can be maintained for each value of the passive element 4b,
This is the range of the passive element 4a that can realize the instant start and the lighting maintenance. Each point in the figure indicates a point where instantaneous start-up and lighting maintenance were actually realized by experiments by the inventor of the present application. Note that the phase angle of the load impedance differs at each point in the figure, and the phase angle moves upward in the region in the figure, and decreases in the downward direction. Approaching sex.

In the region on the right side of the range of the curve shown in FIG. 4, the load impedance tends to be capacitive. Particularly, in the case of a half-bridge inverter, when the load impedance becomes capacitive, the switching elements 6a and 6
b is simultaneously turned on, and the possibility of short-circuit destruction increases, which is not preferable. Further, in the region on the left side of the range of the curve shown in FIG. 4, the load impedance moves too much inductively, the reflected power increases, and the possibility of destruction of the element increases, which is not preferable.

Next, a method of setting the matching circuit 4 so as to fall within the shaded area in FIG. 4 will be described. FIG. 5 shows the passive element 4
The ratio (f ₁ / f ₀ ) of the operating frequency f ₀ of the high-frequency power supply circuit 3 to the resonance frequency f ₁ (hereinafter, referred to as resonance frequency f ₁ ) of the induction coil 2 with respect to the passive element 4 a It is shown. The point in FIG. 5 is the passive element 4a when the lighting is performed at the same frequency in the area shown in FIG.
And from 4b value of it is obtained by calculating the resonance frequency f _1. Here, the capacitance of the passive elements 4a and passive elements 4b and respectively C1, C2, the inductance of the induction coil is L, the resonance frequency f ₁ is calculated by the following equation 1.

F ₁ = 1 / [2π {LC1C2 / (C1 + C2)} ^1/2 ] (Equation 1) As can be seen from FIG. 5, the resonance frequency f ₁ is set to be 0 .0 to the operating frequency f ₀ of the high frequency power supply circuit. 88f ₀ ≦ f ₁ ≦ 0.9
By selecting the passive elements 4a and 4b so as to satisfy the relationship of 5f ₀ , an area where good discharge starting and stable lighting properties can be obtained as shown in FIG. 4 for an arbitrary operating frequency f ₀ . Can be set. In other words, the passive elements 4a and 4b are set to generate a high starting voltage across the induction coil 2 by resonance in the resonance loop. That is, as the value of f ₁ / f ₀ is within the range of .88 to .95, selecting passive elements 4a and 4b, for any operating frequency f _0, the start of good-discharge Stable lighting performance can be obtained.

If the ratio of the resonance frequency f _{1 to} the operating frequency f ₀ is smaller than the above range, the load impedance seen from the high-frequency power supply circuit 3 becomes capacitive. 0.90f ₀ ≤
It is more preferable to design so as to satisfy f ₁ ≦ 0.95f ₀ . However, the inductance of the induction coil 2 has a large error due to the error of the diameter of the ferrite, the deviation of the winding position, and the like, and the error of the inductance in the present embodiment is about 10%. In this case, when an experiment is performed with the same matching circuit constant, the operating frequency f ₀ of the ignitable high-frequency power supply 3 and the resonance frequency f ₁ are slightly shifted according to the inductance of each induction coil 2, and 0.85 f ₀ ≦ f ₁ ≦
It became a 0.97f _0.

Next, reference is made to FIG. FIG. 6 shows the resonance frequency f ₂ and the operating frequency f ₀ of the induction coil 2 and the passive element 4a.
Is shown for the passive element 4a. FIG.
Therefore, the value of the passive element 4a (the point in the figure) is 0.7f ₀ ≦
It can be seen that f ₂ ≦ 0.86f ₀ is satisfied.

Note that the resonance frequency f ₂ is
If the operating frequency f ₀ is smaller than 70% of the operating frequency f ₀ , Equation 1 cannot be satisfied unless the capacitance C2 of the passive element 4b is set to a low value. In the case of the matching circuit 4 used in the present embodiment, the phase angle of the load impedance decreases as the capacitance C2 decreases, and as a result, the load impedance becomes capacitive and the high-frequency power supply circuit 3 generally breaks down. Are known. That is, f _{2 is set} to 70 of f ₀
%, F ₂ is preferably 70% or more of f ₀ .

On the other hand, the resonance frequency f ₂ is
When the operating frequency is higher than 86% of the operating frequency f ₀ , the capacitance C
If 2 is not set to a very large value, Equation 1 cannot be satisfied. When the capacity C2 is set to a very large value,
The reflected power increases and the high-frequency power supply circuit 3 is likely to be broken. In other words, the AC power P
Is obtained from I · V · cos θ (where cos θ
Is the power factor), and the power factor is equal to or more than a predetermined value (for example, cos θ> 1/2).
Otherwise, the current I becomes unnecessarily large, and the high-frequency power supply circuit 3 is easily broken. In other words, since it is possible power factor to prevent or inhibit the breakdown of high-frequency power supply circuit 3, if more than a predetermined, it is preferable that the f ₂ below 86% of f _0.

Accordingly, the passive element 4 is controlled so that the resonance frequency f ₂ is in the range of 0.7f ₀ to 0.86f _0.
It is preferable to select the values of the capacitors C1 and C2 of a and 4b. Hereinafter, a method of selecting C1 and C2 will be described.

First, Equation 2 is derived from the condition of the resonance frequency f ₂ between the passive element 4a and the induction coil 2, and then Equation 3 is obtained from Equation 2.

0.7f ₀ ≦ 1 / {2π (LC1) ^1/2 } ≦ 0.86f ₀ (Equation 2) 1 / {1.72πf ₀ (L) ^1/2 } ≦ (C1) ^1/2 ≦ 1 /{1.4πf ₀ (L) ^1/2 } (Equation 3) Using the above Equation 3, the operating frequency f ₀ of the high-frequency power supply circuit 3
And the inductance L of the induction coil 2,
The range of C1 is required.

Next, Equation 4 is obtained from the relationship between the resonance frequency f ₁ and the operating frequency f ₀ .

0.90f ₀ ≦ f ₁ ≦ 0.95f ₀ (Equation 4) Equation 5 is obtained by substituting Equation 1 into Equation 4. 1.8πf ₀ (L) ^1/2 ≦ [(1 / C1) + (1 / C2)] ^1/2 ≦ 1.9πf ₀ (L) ^1/2 (Equation 5) By substituting the value of C1 obtained by using C3, an appropriate range of C2 can be obtained.

By using C1 and C2 obtained by the above method, it is possible to reliably set the matching circuit 4 within a suitable operation region shown in FIG.

Therefore, the passive elements 4a and 4b
The resonance frequency f ₁ 97% 85% of the operating frequency f ₀ of the high-frequency power supply circuit 3 or less, favorable starting-lighting maintenance performance by more preferably to 95% or less 90% or more between the induction coil 2 and Can be achieved. Further, the induction coil 2 and the passive devices 4a to the resonance frequency f ₂ becomes less 86% 70% of the operating frequency f ₀ of the passive element 4a
By selecting the value, good start-up / lighting maintenance performance can be achieved.

In the present embodiment, the configuration in which the operating frequency f ₀ is about 80 kHz to 100 kHz has been described. However, the configuration of the present embodiment is not limited to the operating frequency. However, when the operating frequency is higher than 500 kHz, the starting voltage of the induction coil 2 required for generating the plasma discharge becomes low and the starting becomes easy, so that the resonance frequency f ₁ is strictly set as in the present embodiment. In some cases, discharge can be started without adjusting the operating frequency f ₀ with the high-frequency power supply circuit 3.
The lighting device that operates at the following relatively low operating frequency exhibits a high effect. On the other hand, if the operating frequency is lower than 50 kHz, the luminous efficiency of the plasma discharge becomes extremely low, which is not preferable.

The circuit configuration of the present embodiment is not limited to the configuration shown in FIG. 3 (or FIGS. 1 and 2), and can be modified to another configuration. FIG. 7 (a) and (b)
Shows a configuration example (modification example) of the matching circuit 4 different from the configuration shown in FIG. Each of the configurations shown in FIGS. 7A and 7B includes a passive element 4 c connected in parallel to the induction coil 2.

The operating frequency f ₀ of the high frequency power supply circuit 3 is 50
In the case of a relatively low frequency such as not less than kHz and not more than 500 kHz, it is necessary to increase the number of turns of the induction coil 2 very much. This is because the magnitude of the magnetic flux required to generate and maintain the plasma discharge is inversely proportional to the frequency. However, an increase in the number of turns leads to an increase in voltage generated at both ends of the induction coil 2 during stable lighting. For this reason, it is necessary to use a considerably high withstand voltage component for the passive element 4c, which leads to an increase in the size of the device. When the configuration of the matching circuit 4 shown in the present embodiment is used, the operating frequency f ₀ is 50 kHz.
In the case of a relatively low frequency of 500 kHz or less, the effect of miniaturization can be obtained by not using large components.
Further, since the higher the possibility of failure due to higher leakage electromagnetic wave is the operating frequency f ₀ becomes higher, the operating frequency f ₀ of 5
The advantage of using a relatively low frequency between 0 kHz and 500 kHz is significant.

Further, in this embodiment, the filling gas of the bulb 1 is argon and mercury, but is not limited thereto. The startability of the discharge is determined by the resonance of the circuit including the induction coil 2 and does not depend on the enclosure of the bulb 1 or the size of the bulb 1. In addition, it is not affected by the number of turns or the inductance of the induction coil 2. Further, in the present embodiment, the Mn-Zn-based ferrite is used for the induction coil, but the material is not limited to the ferrite material.

As described above, either the passive element 4a or the passive element 4b can be constituted by a choke coil. Even when the configuration using the choke coil, is set such that the relationship between the resonance frequency f ₁ and the operating frequency f ₀ satisfies exactly the same relationship, it is possible to obtain the same effect as the configuration using the capacitor. (Embodiment 2) In the above-described embodiment 1, the case where the proximity conductor does not exist has been described.
A description will be given of the start-up / lighting maintenance when a proximity conductor is present near the bulb 1 and the induction coil 2.

FIG. 8 shows an example of the configuration of the discharge lamp lighting device according to the present embodiment. The lighting device of the present embodiment covers the bulb 1, the induction coil 2 provided in the recess of the bulb 1, the high-frequency power supply circuit 3 and the matching circuit 4 housed inside the circuit case 9, and covers them. And a reflection plate 10 provided as follows. In the present embodiment, the reflection plate 10 corresponds to a proximity conductor. The reflecting plate 10 of the present embodiment is an aluminum reflecting plate for a lighting fixture. Specifically, the reflecting plate 10 is provided on the bulb 1 so as to cover the side surface and the bottom surface (the upper surface in the figure) of the bulb 1. It is a reflection plate for a so-called lower surface opening device in proximity.

The operation of the apparatus in this embodiment is as follows.
Since this is as described in the first embodiment, it will not be described in detail in this embodiment. Also in the present embodiment, the operating frequency of the high-frequency power supply circuit 3 is 80 kHz to 100 kHz.
The frequency is adjusted to a frequency at which lighting can be maintained in the range of Hz.

In a state where the reflector 10 (proximal conductor) shown in FIG. 8 is provided, in the same manner as when the area shown in FIG. FIG. 9 shows the result of obtaining possible combinations of the passive elements 4a and 4b. The passive element 4a and the passive element 4
b and the resonance frequency f ₁ ′ of the resonance loop formed by the three elements of the induction coil 2 (hereinafter referred to as the resonance frequency f ₁ ′), and a high-frequency power supply capable of starting and maintaining lighting when a nearby conductor exists. Operating frequency f ₀ ′ (hereinafter, operating frequency f ₀ ′
FIG. 10).

Assuming that the capacitances of the passive elements 4a and 4b are C1 and C2, respectively, and the inductance of the induction coil is L, the resonance frequency f ₁ ′ is given by the above equation (1).
Is calculated by In calculating the resonance frequency f ₁ ′, the reflection plate 1 is used as the inductance of the induction coil 2.
The measured value in the state where 0 exists is used.

If there is no adjacent conductor, the above-mentioned FIG.
As shown in Fig. 9, the startable area is wide and spreads in a band shape.
It becomes a curve like That is, a state in which the band is spread widely becomes a state in which the band is narrow like a line. As described above, the reason that the area where starting and lighting can be maintained is reduced when the proximity conductor is present is that the distribution of the electromagnetic field generated by the induction coil 2 is greatly affected by the presence of the proximity conductor, and the inductance of the induction coil 2 is reduced. In addition, the resistance component increases and the Q value decreases. Here, "Q value"
Means a value obtained by dividing the reactance component (the product of the angular frequency and the inductance) of the impedance of the dielectric coil 2 by the resistance component.

In fact, when the reflector 10 of various lighting fixtures was used, the inductance of the induction coil 2 was reduced to about 80% as compared with the case where the reflector 10 was not provided. Also,
The Q value of the induction coil 2 dropped to about 70%. A decrease in the Q value causes a decrease in the starting voltage generated in the induction coil 2 due to resonance at the time of starting the discharge, which adversely affects the startability. Therefore, it is considered that the discharge can be started and the lighting can be maintained only when the state of the starting resonance is very good.

As shown in FIG. 10, the condition under which the discharge can be started even when the adjacent conductor exists is 0.95f ₀ ′ ≦ f ₁ ′.
It can be seen that the condition satisfies ≦ 0.97f ₀ ′. In other words, under the condition that the value of f ₁ ′ / f ₀ ′ is in the range of 0.95 to 0.97 (a narrow range that can be said to be a substantially constant value), the discharge is started even when the nearby conductor exists. be able to. Therefore, when the matching circuit 4 is set, the starting resonance condition of 0.95f ₀ ′ ≦ f ₁ ≦ 0.97f ₀ ′ is added so that the good starting performance can be obtained even in the presence of a nearby conductor. can get.

When the resonance frequency f ₁ ′ is set outside the above range, the arc discharge is not shifted to the stable lighting state, and only the glow discharge can be generated, or the power is efficiently supplied to the induction coil 2. Phenomena such as the inability to generate a discharge due to the inability to do so occur.

In the present embodiment, in addition to the impedance matching conditions, a starting resonance condition when the inductance and the Q value of the induction coil 2 decrease is added.
It is possible to realize a matching circuit capable of achieving good starting regardless of the presence or absence of the proximity conductor. In the present embodiment, an example in which the operating frequency is 80 kHz to 100 kHz has been described. However, the design of the present embodiment is performed in a relatively low frequency range of 50 kHz to 500 kHz, which is usually difficult to start plasma discharge. A remarkable effect can be obtained by using the region. Therefore, it is not limited to the vicinity of the above-mentioned frequency band. Further, regardless of the enclosure and size of the valve 1 and the inductance and the number of turns of the induction coil 2, if the above resonance conditions are satisfied, good starting characteristics can be obtained.

The first embodiment and the second embodiment
Although the configuration in which the induction coil 2 is inserted into the concave portion of the valve 1 has been described, the positional relationship between the valve 1 and the induction coil 2 is not affected. For example, as shown in FIG.
The induction coil 2 is wound around the valve 1 and the induction coil 2
To the high frequency power generated by the high frequency power supply circuit 3,
The same effect can be obtained in a case where a plasma discharge is generated inside the bulb 1. Therefore,
Modifying the positional relationship between the induction coil 2 and the valve 1 is also within the scope of the present invention. (Embodiment 3) In Embodiments 1 and 2, the case where the operating frequency f ₀ of the high-frequency power supply circuit 3 is adjusted to start and maintain lighting at a certain operating frequency has been described.
In the third embodiment, a case where the operating frequency of the high-frequency power supply circuit 3 is variable will be described.

FIG. 12 shows the configuration of a discharge lamp lighting device according to this embodiment. The lighting device of the present embodiment further includes a variation unit that varies the operating frequency of the high-frequency power supply circuit 3 according to the combined impedance of the matching circuit 4, the induction coil 2, and the plasma generated in the bulb 1. In the present embodiment, the choke coil 8 is provided with a secondary winding, and the oscillation frequency of the oscillation circuit OSC is set in accordance with a signal corresponding to the output of the high-frequency power supply circuit 3 detected by the secondary winding.
That is, the operation frequency of the high-frequency power supply circuit 3 is changed. Other configurations and operations are the same as those in the first and second embodiments, and thus will not be described in detail.

In the case where the lighting device is configured using the matching circuit 4 of the second embodiment, when starting and maintaining the lighting at a constant operating frequency f ₀ , for example, when the inductance of the induction coil 2 largely varies, Frequency f
There is the relationship between the ₁ 'and the operating frequency f _0' becomes inadequate. To avoid this, the high-frequency power supply circuit 3
It is desirable to make the operating frequency f ₀ variable and keep the starting resonance conditions suitable. The control of the operating frequency f _{0 is} such that the output of the secondary winding according to the current flowing through the choke coil 8 is fed back as a control signal to the oscillation circuit OSC, and the high-frequency power supply circuit 3 is connected via the choke coil 8.
This is achieved by introducing a control for slightly changing the operating frequency f ₀ so that the output current or the output power output from the controller becomes an appropriate value. With this control, even when the inductance of the induction coil 2 has a variation of at least ± 10%, it is possible to ensure good start-up / discharge maintenance performance regardless of the presence or absence of the proximity conductor.

In this embodiment, by changing the operating frequency of the high-frequency power supply circuit in accordance with the load impedance, it is possible to provide a matching circuit that achieves good impedance matching even if, for example, elements vary. In the present embodiment, the method of using the output of the secondary winding of the choke coil 8 as the control signal has been described, but the present invention is not limited to this. For example, a configuration in which a small resistor connected in series to the switching elements 6a to 6b is used as a control signal, and a voltage dropped by the small resistor is used as a control signal, or a signal detected by a current transformer connected in series to the switching elements 6a to 6b is used as a control signal. Is also conceivable. The same effect can be obtained by using either method.

[0064]

According to the present invention, the matching circuit is a single circuit having a first passive element and a second passive element, and the first passive element and the second passive element are connected to a resonance loop. Is set to generate a high starting voltage at both ends of the induction coil by the resonance at. For this reason, even when the impedance of the induction coil greatly varies depending on the positional relationship with the adjacent conductor, it is possible to provide a discharge lamp lighting device capable of achieving good starting.

Resonance frequency f₁And high-frequency power circuit
Wave number f₀0.85f₀≤ f₁≤0.97f₀Full
In particular, 0.90f₀≤ f₁≤0.95f₀To
Values of the first passive element and the second passive element to satisfy
Is selected, the resonance frequency f₁And high frequency power circuit
Operating frequency f₀Can never be separated
As a result, good starting characteristics can be realized. Ma
The resonance frequency f between the first passive element and the induction coil;
_TwoIs 0.7f₀≤ f_Two≤0.86f₀Designed to meet
To achieve good starting characteristics.
You. In addition, if the inductance of the induction coil decreases,
Coil, first passive element, and second passive element
Resonance frequency f₁’And the inductance of the induction coil
Of the high-frequency power supply circuit that can be turned on when the
Operating frequency f₀’Is 0.95f₀’≦ f ₁’≦
0.97f₀′, The first passive element and
With the value of the second passive element being selected,
Good starting characteristics can be achieved with or without contact conductors
A discharge lamp lighting device can be realized. in addition,
The first passive element and the second passive element are capacitors.
In this case, a low-loss matching circuit can be provided.

In the case where there is further provided a variation means for varying the operating frequency of the high-frequency power supply circuit in accordance with the combined impedance of the matching circuit, the induction coil and the plasma generated in the bulb, the power consumption after the start of discharge is reduced. It is possible to effectively maintain an appropriate value. Further, by setting the operating frequency of the high-frequency power supply circuit at 50 kHz or more and 500 kHz or less, the possibility of leakage electromagnetic wave interference can be suppressed, and the effect of improving the startability of discharge can be made more remarkable as compared with the prior art.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a discharge lamp lighting device according to the first embodiment.

FIG. 3 is an equivalent circuit diagram after the induction coil according to the first embodiment.

FIG. 4 is a graph showing a design area of the matching circuit according to the first embodiment.

FIG. 5 is a graph (characteristic diagram) showing a ratio between a resonance frequency f _{1 of the} first embodiment and an operating frequency f ₀ of the high-frequency power supply circuit.

FIG. 6 is a graph (characteristic diagram) showing a ratio between a resonance frequency f _{2 of the} first embodiment and an operating frequency f ₀ of the high-frequency power supply circuit.

FIG. 7 is a circuit diagram showing a modification of the configuration of the first embodiment.

FIG. 8 is a cross-sectional view illustrating a configuration of a discharge lamp lighting device according to a second embodiment.

FIG. 9 is a graph showing a design area of the matching circuit according to the second embodiment.

FIG. 10 is a graph (characteristic diagram) showing a ratio between the resonance frequency f ₁ ′ of the second embodiment and the operating frequency f ₀ ′ of the high-frequency power supply circuit.
It is.

FIG. 11 is a sectional view showing a modification of the discharge lamp lighting device according to the second embodiment.

FIG. 12 is a configuration diagram of a discharge lamp lighting device according to a third embodiment.

FIG. 13 is a configuration diagram showing a configuration of a conventional matching circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Valve 2 Induction coil 3 High frequency power supply circuit 4 Matching circuit 41 Starting matching circuit 42 Lighting matching circuit 4a Passive element (first passive element) 4b Passive element (second passive element) 5 DC power supply 6a, 6b Switching element 7 Transformer 8 Choke coil 9 Circuit case 10 Reflector OSC oscillation circuit SW1, SW2, SW3, SW4 Switching means Z _pl Plasma impedance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kawasaki Mitsuharu 1006 Kazuma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 3K072 AA16 DD04 FA05 GA03 GB12 GB18

Claims (8)

[Claims] 1. A valve filled with a discharge gas, an induction coil provided near the valve, a high-frequency power supply circuit for supplying high-frequency power to the induction coil, and a connection between the high-frequency power supply circuit and the induction coil. And a matching circuit for performing impedance matching between the two, wherein the matching circuit comprises: a first passive element connected in series to the induction coil; A single circuit having a second passive element connected in parallel to a series circuit of a first passive element, wherein the induction coil, the first passive element, and the second passive element are provided in a resonance loop. Wherein the first passive element and the second passive element are set to generate a high starting voltage at both ends of the induction coil by resonance in the resonance loop. The discharge lamp lighting device. 2. The inductive coil and the first passive element
Resonance frequency f with the second passive element₁And the high frequency
Operating frequency f of power supply circuit₀0.85f ₀≤ f₁
≤0.97f₀So that the first passive element and
And the value of the second passive element is selected.
2. The discharge lamp lighting device according to 1. 3. The resonance frequency f₁And the operating frequency f₀
0.90f ₀≤ f₁≤0.95f₀I will satisfy
Thus, the first passive element and the second passive element
3. The discharge lamp lighting according to claim 2, wherein a value is selected.
apparatus. 4. A relationship between a resonance frequency f _{2 of} the first passive element and the induction coil and an operating frequency f ₀ of the high-frequency power supply circuit satisfies 0.7f ₀ ≦ f ₂ ≦ 0.86f ₀ . The discharge lamp lighting device according to claim 1, wherein the value of the first passive element is selected as described above. 5. The case where the inductance of the induction coil decreases, and the resonance frequency f ₁ ′ of the induction coil, the first passive element, and the second passive element decreases when the inductance of the induction coil decreases. The first passive element and the second passive element so that the relation with the operating frequency f ₀ ′ of the high-frequency power supply circuit that can be lit satisfies 0.95f ₀ ′ ≦ f ₁ ′ ≦ 0.97f ₀ ′. 5. The discharge lamp lighting device according to claim 1, wherein a value of the passive element is selected. 6. The discharge lamp lighting device according to claim 1, wherein each of the first passive element and the second passive element is a capacitor. 7. A variation means for varying the operating frequency of the high-frequency power supply circuit according to a combined impedance of the matching circuit, the induction coil, and plasma generated in the bulb. The discharge lamp lighting device according to any one of the above. 8. The high-frequency power supply circuit operates at a frequency of 50 kHz or more and 500 kHz or less.
The discharge lamp lighting device according to any one of the above.