JPH0436052Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Purpose of the invention] (Industrial application field) The invention relates to a low-pressure discharge lamp such as a fluorescent lamp, which is formed by connecting a plurality of bulbs by a connecting member. The present invention relates to a low-pressure discharge lamp with reduced starting voltage and lighting maintenance voltage.

(Prior art) There are various types of low-pressure discharge lamps in recent years that incorporate fluorescent lamps with meandering discharge paths.
As shown in the figure, a single straight glass bulb 1 is bent into a U-shape, and then bent again into a U-shape around the middle part of this U-shape, a so-called saddle shape. There's a lamp.

In addition, as shown in FIGS. 9 and 10, 1
The U-shaped bent portions 2a are continuously bent on a book glass bulb 2, for example, at five locations, and the electrode sealing ends for sealing the two integrated electrodes are arranged in parallel in close proximity. There is a so-called 3U type lamp.

Further, as a fluorescent lamp having a meandering discharge path, there is a fluorescent lamp described in the specification of Japanese Patent Application No. 114814/1983 filed by the present applicant, which has a disc-shaped shape as shown in FIGS. 11 and 12. On a ceramic substrate 3, for example, three glass bulbs 4, 4, 4, which are bent into an inverted U shape, are arranged in an annular manner and stand upright.

The inner cavities of these glass bulbs 4, 4, 4 are
They communicate with each other through the inner cavity of the communication recess 5 formed in the substrate 3, forming one meandering discharge path, and a lid plate 6, 6 is airtightly fitted and fixed with an adhesive such as glass frit.

In FIGS. 11 and 12, reference numeral 7 is a main electrode, and reference numeral 8 is a globe of an envelope whose open end is fitted around the outer periphery of the substrate 3 to cover the glass bulb 4.

Fluorescent lamps configured in this way are shown in Figures 8 to 1.
It is easier to process than the structure shown in FIG. 0, and since the glass bulbs 4, 4, 4 are fixed on the substrate 3,
It has the advantage that a separate maintenance mechanism for holding the parts 4 and 4 is not required.

However, in this type of fluorescent lamp, the discharge path is meandering and long, so the starting voltage is high.As a result, the lighting circuit (not shown), starter (not shown), etc. are large in size. These and other electric elements have drawbacks such as high breakdown voltage and low circuit efficiency.

Therefore, in conventional low-pressure discharge lamps, a needle-shaped auxiliary electrode is inserted from the outside into the axially middle part of the glass bulb, and the insertion tip is exposed to the axially middle part of the meandering discharge path. Some types apply a starting voltage to an auxiliary electrode.

However, this method is extremely difficult to maintain airtight at the penetration part where the needle-shaped auxiliary electrode penetrates the glass bulb, so it is extremely unlikely to be implemented. There is a problem that the reduction effect is extremely low.

There are also fluorescent lamps that reduce the starting voltage between the main electrodes by applying a required voltage to a metal holder that holds the outer periphery of the axially intermediate part of the glass bulb, but this method does not allow the starting voltage to be lowered between the main electrodes. Since the electric field is applied from the outside via the main electrode, there is a problem that the effect of reducing the starting voltage between the main electrodes is still low.

(Problems to be solved by the invention) As mentioned above, in conventional low-pressure discharge lamps in which a needle-shaped auxiliary electrode is provided or a metal holder is used as a holding electrode, the effect of reducing the starting voltage between the main electrodes is low. There's a problem.

Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a low-pressure discharge lamp that can lower the starting voltage and lighting maintenance voltage between the main electrodes.

[Structure of the idea]

(Means for Solving the Problems) The present invention was made by focusing on a connecting member that connects a plurality of valves, and is characterized in that this connecting member is made of a metal material and constitutes an auxiliary electrode. It is composed as follows.

In a low-pressure discharge lamp in which the connecting ends of a plurality of bulbs are airtightly connected to each other by a connecting member to integrally connect the discharge paths of each bulb, at least the portion facing the discharge path of the connecting member is made of metal. It is made of a material and is configured as an auxiliary electrode to which a voltage is applied.

(Function) When a low-pressure discharge lamp is lit, a starting voltage is applied between the main electrodes and the auxiliary electrode made of the connecting member.

Since the auxiliary electrode is placed halfway between the main electrodes, the distance between the auxiliary electrode and the main electrode is shorter than the distance between the main electrodes. occurs, and then a discharge occurs between the main electrodes, lighting the low-pressure discharge lamp.

That is, first, when a discharge occurs between the auxiliary electrode and the main electrode, the impedance of the discharge path between them decreases, so the impedance of the discharge path between the main electrodes that partially share this discharge path decreases.

For this reason, the discharge starting voltage between the main electrodes decreases.

In addition, after lighting a low-pressure discharge lamp, a lighting sustaining voltage to maintain lighting is applied between the main electrodes and between the auxiliary electrodes, so a discharge between the main electrodes occurs every half cycle of this lighting sustaining voltage. Even when the
A discharge occurs between the main electrode and the auxiliary electrode.

Therefore, it is possible to prevent the discharge between the main electrodes from disappearing every half cycle of the lighting sustaining voltage and to reduce the lighting sustaining voltage.

Therefore, according to the present invention, both the discharge starting voltage between the main electrodes, that is, the starting voltage and the lighting maintenance voltage can be lowered, so that the lighting circuit, starter, etc. can be made smaller and lighter. I can do it.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 is a perspective view showing a fluorescent lamp according to an embodiment of the present invention. In the figure, a bulb 11 is erected on a disk-shaped substrate 10 made of ceramics, etc. The open end of the bulb-shaped globe 12 is fitted and fixed to the outside and covers the outer periphery of the bulb 11.

The bulb 11 is composed of, for example, three inverted U-shaped glass bulbs 11a, 11b, and 11c, and is arranged annularly on the substrate 10.

Two of the bulbs 11a, 11b, 11c have a pair of main electrodes 13a, 13 at one end of each bulb 11a, 11b, which are juxtaposed close to each other.
b are each sealed, and the other end and the valve 11
Both ends of c are formed at connection ends.

The connecting ends of these bulbs 11a, 11b, 11c are airtightly connected by a connecting member 14, and the discharge paths within each bulb 11a, 11b, 11c are integrally connected through the inner cavity of the connecting member 14.

Moreover, as shown in FIG. 2, each valve 11a, 1
A phosphor film 15 made of phosphor is coated on the inner wall of each bulb 1b and 11c over almost the entire length.
1a, 11b, 11c and the connecting member 14 are filled with mercury gas and a rare gas such as argon gas at low pressure.

The connecting member 14 includes a connecting recess 14a that is recessed into a bowl shape on the upper surface of the substrate 10, and a metal lid plate that is fixed to the open end of the connecting recess 14a, which has an oval shape in plan, with a glass frit or the like to form an airtight seal. 14b, and are formed at two locations, for example.

That is, each lid plate 14b, 14b has a communication port that communicates with the open end of each connection end of each valve 11a, 11b, 11c, as shown in FIG. Vertically rising annular peripheral walls 16 are respectively provided, and these annular peripheral walls 16 are hermetically fitted into the open end of each connection end of each bulb 11a, 11b, 11c and fixed with glass frit or the like.

On the upper surface of each cover plate 14b, 14b,
Power supply line 17 electrically connected to a power source (not shown)
are electrically connected to each other, and each cover plate 14b, 1
Reference numeral 4b constitutes an auxiliary electrode to which a starting voltage and a lighting maintenance voltage are applied from a power source.

Note that in FIGS. 1 and 2, reference numeral 18 is an exhaust pipe.

FIG. 3 shows a fluorescent lamp 20 according to another embodiment of the present invention.
This fluorescent lamp 20 has an inverted U-shape and has two bulbs 21 and 22 made of glass, for example, and connecting portions 21a and 22a of the bulbs 21 and 22 are hermetically connected to a connecting member 23. This connecting member 23 includes a substrate 23a whose surface is a metal plate coated with a glass thin film,
It is comprised of a bowl-shaped metal cap 24 fixed to approximately the center of the lower surface of the substrate 23a.

The substrate 23a, which constitutes a part of the connecting member 23, is a metal plate whose surface is entirely coated with an electrically insulating film made of glass or the like, and each connection portion 21a of the bulbs 21 and 22 erected thereon. , 22a, communicating holes 23b, 23b of a required diameter are bored, respectively.
A metal cap 24 is hermetically fixed to the lower surface of the cap 23b so as to cover the entire outer periphery of the communicating holes 23b, 23b.

Therefore, the discharge spaces inside both the bulbs 21 and 22 are airtightly communicated via the connecting member 23 consisting of the substrate 23a and the metal cap 24, and are formed into one meandering discharge path.

The metal cap 24 is formed of a metal plate into a bowl shape, and is connected to a power supply (not shown) via a power supply line 25, and is connected to an auxiliary electrode to which a starting voltage and a lighting maintenance voltage are applied from the power supply when the fluorescent lamp 20 is lit. It is configured.

In FIG. 3, numerals 26a and 26b are a pair of main electrodes, and 27 is a phosphor coating made of phosphor.

Therefore, when lighting the fluorescent lamp 20, a starting voltage is applied between the main electrodes 26a and 26b and to the metal cap 24 of the auxiliary electrode. Therefore, first, a discharge occurs between the metal cap 24 and the main electrodes 26a and 26b, and then,
Discharge is started between the main electrodes 26a and 26b, and the bulbs 21 and 22 are lit.

That is, when a discharge occurs between the metal cap 24, which is an auxiliary electrode, and the main electrodes 26a, 26b, the impedance of the discharge path between them decreases, and the main electrodes 26a, 26b share a part of the discharge path with reduced impedance. Since the impedance between them is reduced as a whole, discharge between the main electrodes 26a and 26b can be started at a low voltage, and the starting voltage can be reduced.

Further, after lighting the fluorescent lamp 20, the lighting maintenance voltage for maintaining the lighting is applied to the main electrodes 26a and 26.
6b and between the auxiliary electrodes 24,
The main electrode 26 for every half cycle of this lighting maintenance voltage.
Even when the discharge between the main electrodes 26a and 26b disappears, a discharge occurs between the main electrodes 26a and 26b and the auxiliary electrode 24.

Therefore, it is possible to prevent the discharge between the main electrodes 26a and 26b from fading out every half cycle of the lighting sustaining voltage, and to reduce the lighting sustaining voltage.

Although this embodiment describes the case where the metal cap 24 is configured as an auxiliary electrode, the present invention has the following features:
For example, the power supply line 2 is not limited to this.
5 may be electrically connected to a metal plate of a substrate 23a, and this substrate 23 may be configured as an auxiliary electrode to which a starting voltage and a lighting maintenance voltage are applied.

Further, the inner surface of the metal cap 24 may be coated with an electrically insulating coating such as a thin glass film to prevent impurity gas from being released from the metal cap 24 during discharge.

FIG. 4 shows an electric circuit of a low-pressure discharge lamp 30 incorporating the fluorescent lamp of the embodiment shown in FIGS. However, for convenience of drawing, it is shown as a straight pipe here.

Each primary side of the pair of main electrodes 13a, 13b of the valve 11 is connected to the output end of a high frequency inverter circuit 31 that converts direct current into high frequency alternating current of 40KHz, for example, and the input end of the high frequency inverter circuit 31 is connected to the output end of the high frequency inverter circuit 31 through a rectifier circuit 32. It is connected to a commercial power source 33.

On the other hand, a pair of main electrodes 13a13b of the bulb 11
34 is connected to each secondary side starter, and each cover plate 14b, 14b (see FIGS. 1 and 2), which is an auxiliary electrode, is connected to one of the input ends of the high-frequency inverter circuit 31 via a power supply line 17. Furthermore, a starting capacitor 35 and a resistor 36 for phase adjustment are interposed in the middle of the power supply line 17.

Next, the operation of this embodiment will be explained with reference to FIG.

When the commercial power supply 33 voltage is applied to the rectifier circuit 32, a high frequency AC voltage of, for example, 40 KHz is applied as a starting voltage from the output end of the high frequency inverter circuit 31.
Between the main electrodes 13a and 13b and the cover plate 14 of the auxiliary electrode
b, 14b, respectively.

Each cover plate 14b, 14b of the auxiliary electrode and the main electrode 13
The distance between main electrodes 13a and 13b is smaller than that between main electrodes 13a and 13b.
Since the distance is shorter than the distance between the lid plates 14b, 14b and the main electrodes 13a, 13b, a glow discharge is first generated between each cover plate 14b, 14b and the main electrodes 13a, 13b, and after the impedance of the discharge path decreases, the main electrodes 13a, 13b
Discharge begins between the two.

That is, the cover plates 14b, 14b and the main electrode 13
When a discharge occurs between a and 13b, the impedance of the discharge path between them decreases.
The impedance between the main electrodes 13a and 13b, which partially share the discharge path with reduced impedance, is reduced as a whole. For this reason, discharge is started between the main electrodes 13a and 13b at a low starting voltage, and the bulb 11 is lit.

Therefore, since the starting voltage between the main electrodes 13a and 13b is reduced, the cover plates 14b and 1 of the auxiliary electrodes are reduced.
The starting voltage can be lowered to, for example, 1/4 to 1/3 of that without 4b.

Further, after the bulb 11 is lit, the lighting maintenance voltage for maintaining the lighting is applied to the main electrodes 13a and 13b.
Since the voltage is applied between the main electrodes 13a, 13b and between the auxiliary electrodes 14a, 14b, even when the discharge between the main electrodes 13a, 13b disappears every half cycle of this lighting maintenance voltage, the voltage between the main electrodes 13a, 13b and the auxiliary electrodes 14a, 14b is A discharge occurs between the two.

Therefore, it is possible to prevent the discharge between the main electrodes 13a and 13b from fading out every half cycle of the lighting sustaining voltage, and to reduce the lighting sustaining voltage.

As a result, it is possible to reduce the withstand voltage of the electrical components constituting the high frequency inverter circuit 31 and to reduce the size and weight of transformers.

Furthermore, since the output voltage of the high-frequency inverter circuit 31 can be lowered, the step-up ratio of the high-frequency inverter circuit 31 can be suppressed to a low level, and the circuit current can be reduced, so that circuit efficiency can be improved.

Note that the fluorescent lamp shown in FIGS. 1 and 2 can also be applied to the low-pressure discharge lamp 40 shown in FIG. is constructed by replacing the step-up transformer 41 with a step-up transformer 41.
Since it is the same as that shown in the figure, the fourth
Parts common to those in the figures are given the same reference numerals, and their explanations will be omitted.

This low-pressure discharge lamp 40 also has almost the same effects as the low-pressure discharge lamp 30 shown in FIG. It is possible to prevent the display from disappearing.

Furthermore, even when the fluorescent lamp 20 shown in FIG. 3 is applied to the low-pressure discharge lamps 30 and 40 shown in FIG. 4 or 5, the same applies as when the fluorescent lamp shown in FIGS. 1 and 2 is applied. , main electrode 2
The starting voltage between 6a and 26b can be lowered.

FIG. 6 is a circuit diagram showing another embodiment of the present invention, and this low-pressure discharge lamp 50 has straight tube-shaped, for example, two glass bulbs 51 and 52 arranged in parallel, and each connection having an open end. A metal cap 53, which is a connecting member, is hermetically fitted to the end portions 51a, 52a to integrally connect the discharge paths of both bulbs 51, 52.
The metal cap 53 is made of a metal cylindrical airtight container, and one surface (lower surface in FIG. 5) of the metal cap 53 is provided with communication holes 53a, 53a into which the open ends of the connection ends of the respective valves 51, 52 are hermetically fitted. installed, both valves 5
The lumens 1 and 52 communicate with each other through the lumen of the metal cap 53.

Both bulbs 51 and 52 have a phosphor film made of phosphor adhered to their inner walls over almost the entire length, and are filled with mercury gas and a rare gas such as argon gas at low pressure. The main electrodes 54a and 54b are sealed.

Each main electrode 54a, 54b is connected via a step-up transformer 55 to a high frequency oscillator 56 containing a power supply (not shown).
A high frequency alternating current voltage of OKHz is output, and after being boosted by a step-up transformer 55, it is applied to a pair of main electrodes 54.
It is designed to be applied between a and 54b.

The secondary side of the step-up transformer 55 is connected to the metal cap 53 via a power supply line 57, and in the middle of the power supply line 57 there is an on/off switch 58 that is closed only during startup.
and a resistor 59 are interposed in series, and the metal cap 5
Reference numeral 3 constitutes an auxiliary electrode to which a power supply voltage is applied.

This low-pressure discharge lamp 50 is suitable for a so-called back light, etc., which illuminates a liquid crystal display panel incorporating a transmissive liquid crystal from behind, and is suitable for the so-called backlight etc.
(See Figure 4), the starting voltage and lighting sustaining voltage between the main electrodes 54a and 54b are reduced, and the discharge between the main electrodes 54a and 54 is prevented from disappearing every half cycle of the lighting sustaining voltage. be able to.

That is, when starting the lighting of the low pressure discharge lamp 50, a starting voltage is applied between the main electrodes 54a and 54b and to the metal cap 53, which is an auxiliary electrode.

Since the metal caps 53 are placed halfway between the main electrodes 54a and 54b,
Since the distance between the main electrodes 54a, 54b and the metal cap 53 is shorter than the distance between them, first, discharge occurs between the main electrodes 54a, 54b and the metal cap 53, and the discharge between them occurs. lower the impedance of the path.

For this reason, the overall impedance of the discharge path between the main electrodes 54a and 54b, which share a part of the discharge path with reduced impedance, is reduced, so that the discharge generated between the main electrodes 54a and 54b has a low starting voltage. will be started.

For example, the bulb 51 of the low pressure discharge lamp 50,
The direct diameter of 52 is 8 mm, and the argon gas filling pressure is
Set to 4torr and apply to metal cap 53 at startup.
When a current of 1.5mA flows, the starting voltage is approximately
The starting voltage is about 460V, whereas the starting voltage when no current flows through the metal cap 53 is 580V.
It was possible to lower the starting voltage.

Further, in the low pressure discharge lamp 50 configured as described above, as shown in FIG.
A high resistance 61 is interposed in the power supply line 57 in parallel with the resistance value of the high resistance 61 with respect to the resistance 59.
For example, in the case of the low-pressure discharge lamp 60 set to about 10 times, it is possible to suppress the striped discharge phenomenon that occurs relatively often during low-temperature lighting.

This striped discharge phenomenon is a phenomenon in which the brightness of the lit bulbs 51 and 52 appears in stripes, and the light and dark stripes flow in the axial direction of the bulbs 51 and 52, and is considered to be a type of acoustic resonance phenomenon. However, by passing a minute current to the metal cap 53 through the high resistance 61 while the bulbs 51 and 52 are turned on, the striped discharge phenomenon can be suppressed.

This effect of suppressing the striped discharge phenomenon could be confirmed through experiments.

In addition, in each of the above embodiments, one or two auxiliary electrodes are used.
Although the present invention is not limited to this, three or more auxiliary electrodes may be provided, and the auxiliary electrode may be a connecting member that connects a plurality of bulbs. Furthermore, the present invention can be applied to a low-pressure discharge lamp of a half-cycle start type, thereby making it possible to reduce the lighting sustaining voltage.

[Effect of idea]

As explained above, in the present invention, among the connecting members that connect the connection ends of a plurality of bulbs, the part facing the discharge path in the bulb is formed of a metal material, and the auxiliary electrode to which voltage is applied is formed. With this configuration, first, a discharge can be generated between the bulb main electrode and the auxiliary electrode, and the impedance of the discharge path therebetween can be reduced.

Therefore, the impedance between the main electrodes that share a part of the discharge path with reduced impedance is reduced as a whole, so the discharge between the main electrodes can be started at a low voltage, which reduces the starting voltage. can be achieved.

In addition, after lighting a low-pressure discharge lamp, a lighting sustaining voltage to maintain lighting is applied between the main electrodes and between the auxiliary electrodes, so a discharge between the main electrodes occurs every half cycle of this lighting sustaining voltage. Even when the
A discharge occurs between the main electrode and the auxiliary electrode.

Therefore, it is possible to prevent the discharge between the main electrodes from disappearing every half cycle of the lighting sustaining voltage and to reduce the lighting sustaining voltage.

As a result, the lighting circuit, starter, etc. can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a fluorescent lamp incorporated into an embodiment of a low-pressure discharge lamp according to the present invention, and FIG.
FIG. 3 is a partially developed vertical sectional view showing a partially developed vertical sectional view so that the vertical planes of the bulbs on both sides coincide with the vertical plane of the bulb disposed at the right end in the figure. 4 and 5 are circuit diagrams of a low-pressure discharge lamp incorporating the fluorescent lamps shown in FIGS. 1 and 2, and FIGS. 6 and 7 are diagrams showing other circuit diagrams of the present invention. 8 is a perspective view of a conventional fluorescent lamp, FIG. 9 is a perspective view of another conventional example, FIG. 10 is a plan view of FIG. 9, and FIG. 11 is a diagram of another conventional fluorescent lamp. A perspective view of a conventional example,
FIG. 12 is a partially developed vertical cross-sectional view showing a part of the valve disposed at the right end in FIG. 11 in a partially developed manner so that the vertical planes of the bulbs on both sides thereof coincide with the vertical plane of the bulb disposed at the right end in FIG. 10, 23...Substrate, 11, 11a,, 11b,
11c, 21, 22, 51, 52...Valve, 1
3a, 13b, 26a, 26b, 54a, 54b
...Main electrode, 14, 53...Connection member (auxiliary electrode).

Claims (1)

[Claims for Utility Model Registration] 1. A low-pressure discharge lamp in which the connecting ends of a plurality of bulbs are airtightly connected to each other by a connecting member to integrally connect the discharge paths of each bulb, at least The part facing the above discharge path,
A low-pressure discharge lamp characterized in that it is made of a metal material and has an auxiliary electrode to which a voltage is applied. 2. The connecting member has a recess in the substrate through which the open end of the connection end of the inverted U-shaped valve communicates, and a cover plate that airtightly closes the open end of the recess, and the cover plate is made of a metal material. The low-pressure discharge lamp according to claim 1, characterized in that the lamp is configured as an auxiliary electrode. 3. A utility model characterized in that the connecting member is made of a metal cap that airtightly connects the connecting ends of a plurality of straight tubular valves arranged in parallel, and the metal cap is configured as an auxiliary electrode. A low pressure discharge lamp according to claim 1.