JPH09161726A - Noble gas discharge lamp, lighting device, and image reading device - Google Patents

Abstract

(57) [Summary] [Object] To provide a rare gas discharge lamp and a lighting device using the same, in which the starting characteristics are stable even if the cold cathode is deviated, and a reliable starting is possible. SOLUTION: An auxiliary electrode 6 having one end connected to a power source is arranged along the tube axis direction on the outer surface of a valve 1 in which electrodes 2a and 2b are sealed at both ends and a rare gas is sealed inside. The rare gas discharge lamp is characterized in that a conductive member 7 extending along the circumferential direction of the bulb 1 is provided at the other end of the auxiliary electrode 6. According to the above configuration, since the conductive member 7 extending in the circumferential direction of the bulb is provided at the tip of the auxiliary electrode 6, the electrode 2b is formed.
Does not move away from the conductive member 7 even if it is deviated from the valve center. Therefore, the distance between the electrode 2b and the conductive member 7 can be kept below a certain value, and the variation in the starting characteristics can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare gas discharge lamp and a lighting device having a bulb filled with a rare gas such as neon or xenon, and an image reading apparatus using the same.

[0002]

2. Description of the Related Art Recently, a rare gas cold cathode discharge lamp has been used as a light source for various OA devices such as an image reading device. A rare gas cold cathode discharge lamp has high luminous efficiency, can obtain bright light with low power consumption, and can form an elongated light source.Therefore, it can be advantageously used as a light source of an image reading device that needs to scan a paper surface having a predetermined width. is there. Moreover, the rare gas cold cathode discharge lamp has neon (Ne) or xenon (Xe) inside the bulb.
Since it is filled with a rare gas such as, there is also an advantage that there is little change in brightness depending on the ambient temperature condition.

By the way, for this type of light source, it is required to increase the brightness of the light emitted from the light source in order to read an image clearly. In order to increase the brightness in this type of rare gas discharge lamp, it is necessary to increase the pressure of the enclosed gas of neon or xenon.

However, if the pressure of the rare gas is increased, the starting voltage will increase. That is, in general, the rare gas discharge lamp tends to have difficulty in ionizing the enclosed rare gas, and thus has a problem that the startability is poor as compared with a fluorescent lamp in which mercury is enclosed. In addition, when the pressure of the rare gas is increased, the starting voltage becomes higher and higher.

If the pressure of the rare gas is increased, the positive column is narrowed during lighting and the thin positive column is distorted or shaken (snake phenomenon) in the bulb to discharge. There is also the problem of instability.

In order to solve the problems of the startability and the snake phenomenon, it has been proposed to provide an auxiliary electrode on the outer surface of the valve along the tube axis direction. That is, an auxiliary electrode made of a conductive tape or the like is formed on the outer surface of the bulb along the tube axis direction, and one end of this auxiliary electrode is connected to a power source. In this way, when a starting voltage is applied to the cold cathode sealed at both ends of the bulb and the auxiliary electrode, a local discharge is first induced between one cold cathode and the tip of the auxiliary electrode formed on the outer surface of the bulb. As a result, a large amount of electrons are supplied into the bulb, and the local discharge extends toward the center of the bulb and grows into a full discharge. Therefore, the auxiliary electrode induces a discharge and becomes easier to start,
The starting voltage can be lowered.

When the auxiliary electrode is provided on the outer surface of the bulb along the tube axis as described above, the positive column is attracted to the auxiliary electrode during stable lighting and deviates from the center line of the bulb. However, the distortion and shaking (snake phenomenon) of the positive column are prevented, and the discharge is stabilized.

[0008]

By the way, in the conventional case, since the auxiliary electrode provided on the outer surface of the bulb is attached to the outer surface of the bulb in the form of a strip or a line, it is extended to the vicinity of one cold cathode. However, it is formed on one side of the outer surface of the valve.

On the other hand, since one cold cathode is originally installed at the central position of the bulb, the cold cathode and the tip of the auxiliary electrode should keep a certain distance, but at the end of the bulb. The sealed cold cathode may be displaced from the center of the bulb during the sealing process, and after sealing, the electrode shaft and internal lead wires are bent due to vibration or shock, which causes the cathode to be displaced from the center of the bulb. There are also things to do. When the eccentric direction of the cold cathode approaches the auxiliary electrode side provided on the outer surface of the bulb, the distance between the cold cathode and the auxiliary electrode becomes short, which facilitates starting, and conversely the eccentric direction of the cold cathode is If the distance from the auxiliary electrode is increased, the distance between the cold cathode and the auxiliary electrode becomes long, which makes it difficult to start.

However, in the case where the above-mentioned deviation occurs in the cold cathode, the direction thereof is not constant, and therefore such a deviation causes a variation in the starting characteristics among the lamps.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a rare gas discharge lamp which has a stable starting characteristic even if the cold cathode is deviated and which enables a reliable starting. Another object of the present invention is to provide a lighting device using the same.

[0012]

In order to achieve the above-mentioned object, the invention of claim 1 is a valve having electrodes sealed at both ends and a rare gas sealed inside; a tube shaft on the outer surface of the valve. An auxiliary electrode that is arranged along the direction and has one end connected to a power source; and a conductive member that is provided at an end portion of the auxiliary electrode opposite to the power source connection side end portion and extends along the circumferential direction of the valve. It is a rare gas discharge lamp characterized by comprising.

According to the first aspect of the present invention, since the conductive member extending in the circumferential direction of the valve is provided at the tip of the auxiliary electrode, even if the internal electrode is deviated from the valve center, the conductive member exists in the deviating direction. Therefore, the electrode does not move away from the conductive member. For this reason, the electrode and the conductive member can be installed at a certain distance or less, the discharge starting characteristic is stabilized, and the variation in the starting property is reduced.

According to a second aspect of the present invention, there is provided the rare gas discharge lamp according to the first aspect, wherein the conductive member is formed at a position overlapping one electrode adjacent to the conductive member in a side view. Since the conductive member is formed at a position overlapping one of the electrodes facing the conductive member in a side view, the electrode and the conductive member can be placed close to each other.

A third aspect of the present invention is the rare gas discharge lamp according to the first or second aspect, wherein the conductive member is formed over 270 ° or more along the circumferential direction of the bulb. .

The conductive member 270 is provided along the circumferential direction of the bulb.
Since it is formed over more than 50 °, it is possible to install the electrode and the conductive member within a certain distance no matter which direction the electrode is displaced from the center of the bulb.

The invention according to claim 4 is characterized in that the conductive member is constituted by adhering a conductive adhesive tape to the outer surface of the valve, and the rare member according to any one of claims 1 to 3. It is a gas discharge lamp.

Since the conductive member is formed of a conductive adhesive tape, the conductive member can be easily formed on the outer surface of the valve. The invention according to claim 5 is characterized in that the conductive member is constructed by additionally mounting a conductive foil on the outer surface of the bulb, and the rare gas discharge lamp according to any one of claims 1 to 3. Is.

Since the conductive member is made of conductive foil, the conductive member can be easily formed on the outer surface of the valve. The invention according to claim 6 is the rare gas discharge lamp according to any one of claims 1 to 5, characterized in that the outer surface of the conductive member is subjected to an insulation treatment.

Since the outer surface of the conductive member is insulated, problems such as short-circuit due to contact with the surrounding conductive member can be prevented. The invention according to claim 7 is the rare gas discharge lamp according to any one of claims 1 to 6, which is housed in the discharge lamp and has a substantially gutter shape extending along the tube axis direction of the discharge lamp. And a formed reflector, which is an illuminating device.

According to the invention of claim 7, it is possible to provide an illuminating device having stable starting characteristics, stable discharge during lighting, and high brightness. The invention of claim 8 is
An image reading apparatus using the above illumination device.

According to the eighth aspect of the present invention, it is possible to provide an image reading apparatus which has stable starting characteristics, stable discharge during lighting, high brightness, and therefore clear image reading.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment shown in the drawings. FIG. 1 shows a neon glow discharge lamp, in which 1 is a bulb made of an elongated glass tube. This valve 1 has an inner diameter of 1.0-1
It is formed to 0.0 mm, specifically, the inner diameter is 4.7 mm
(Outer diameter 5.8 mm). Also, this valve 1 has a valve length of 50 to 1000 mm, specifically 255
mm, and the cold cathode 2 is attached to both ends of the bulb 1.
a and 2b are sealed. The cold cathodes 2a and 2b are configured by joining an electrode shaft 22 to a cylindrical electrode body 21 made of, for example, nickel, and the electrode shaft 22 is hermetically sealed at the end of the bulb 1 of the Dumet wire 3 , 3 to external lead wires 4, 4.

A fluorescent substance coating 5 is formed on the inner surface of the bulb 1, and a rare gas mainly containing neon (Ne) is enclosed in the bulb 1. The noble gas may be all neon, but some argon (0.5% or less) may be added for good starting. 60 for neon
The filling pressure is 100 Torr, and in this example, the filling pressure is 100 Torr.

On the outer surface of the bulb 1, a long strip-shaped auxiliary electrode 6 is provided in close contact along the tube axis direction. In the case of this embodiment, the auxiliary electrode 6 is provided on the outer surface of the bulb 1.
It is configured by adhering a conductive tape made of an aluminum adhesive tape.

In this case, in the region where the auxiliary electrode 6 made of a conductive adhesive tape is attached, the end portion of the auxiliary electrode 6 is closer to the tube end side along the tube axis direction than the tips of the cold cathodes 2a and 2b. The end portion of the auxiliary electrode 6 overlaps with the electrode bodies 21 of the cold cathodes 2a and 2b in a side view. The width of the auxiliary electrode 6 is 5% or more of the outer circumference of the bulb,
It is set to 50% or less.

One end 6a of the auxiliary electrode 6 is connected to a power source, for example, a high frequency oscillator 8. This high-frequency oscillator 8 has a frequency of 10 kHz or more and 60 kHz or less, specifically 2 kHz.
The high frequency power of 0 kHz is supplied to turn on the lamp.

The cold cathodes 2a and 2b sealed at both ends of the bulb 1 are connected to the terminals 9a and 9b of the high frequency oscillator 8, and the one end 6a of the auxiliary electrode 6 is connected.
Is connected to one terminal 9a so as to have the same polarity as one cold cathode 2a close to this.

A conductive member 7 is provided on the other end of the auxiliary electrode 6, that is, the tip 6b. The conductive member 7 extends along the circumferential direction of the bulb 1 and is provided so as to surround the electrode body 21 of one cold cathode 2b adjacent to the conductive member 7. That is, the conductive member 7 is formed at a position overlapping with the electrode body 21 with respect to the one electrode 2b close to the conductive member 7 in a side view, and in the range of at least 270 ° or more along the circumferential direction of the bulb 1. It is formed over the entire circumference, and in this example, it is formed over the entire circumference as shown in FIG. 1 (B).

In the present embodiment, the conductive member 7 is also
A conductive adhesive tape is adhered to the outer surface of the bulb 1. The outer surfaces of the auxiliary electrode 6 and the conductive member 7 are
An insulating coating process is performed by covering with a transparent insulating tape (not shown).

The rare gas cold cathode discharge lamp having such a structure is
A high frequency power of 20 kHz is supplied from the high frequency oscillator 8 to perform high frequency lighting. During lighting, glow discharge is generated between the cold cathodes 2a and 2b, and the glow discharge ionizes the rare gas such as neon and xenon enclosed in the bulb 1.
Therefore, it emits light. Of the emitted light, ultraviolet rays are converted into visible light by the phosphor coating 5 and emitted to the outside.

In this type of rare gas discharge lamp, the brightness becomes higher when the pressure of the rare gas is increased, but when the pressure of the filled gas is increased, the rare gas is less likely to be ionized and the starting voltage becomes higher. In addition, when the filling pressure of the rare gas is increased, the positive column converges and becomes thin during lighting, and the thin positive column causes distortion and shaking (snake phenomenon) in the bulb 1, resulting in unstable discharge. There is also the problem of becoming.

To solve this problem, in this embodiment, the valve 1
Since the auxiliary electrode 6 is attached to the outer surface of the tube along the tube axis direction,
The starting can be facilitated and the discharge can be stabilized.
That is, at the time of starting, a voltage is applied between the cold cathodes 2a and 2b from the high-frequency oscillator 8 and also a voltage is applied between the auxiliary electrode 6 and the cold cathode 2b adjacent to the tip 6b. . Therefore, the tip 6b of the auxiliary electrode 6
And a local discharge is induced between the cold cathode 2b and one of the cold cathodes 2b, thereby supplying a large amount of electrons into the bulb 1.
Then, the local discharge extends toward the central portion of the bulb 1, and this grows into a glow discharge between the electrodes 2a and 2b, thereby becoming a full discharge. In this way, the auxiliary electrode 6 induces the starting discharge, thus facilitating the starting, and the starting voltage can be lowered.

When the auxiliary electrode 6 is provided on the outer surface of the bulb 1 along the tube axis direction, the positive column is attracted to the auxiliary electrode 6 during stable lighting, and the positive column is distorted or shaken (snake phenomenon). ) Is prevented and the discharge becomes stable.

In this embodiment, the tip 6 of the auxiliary electrode 6 is
b, that is, the end 6b opposite to the end 6a connected to the high-frequency oscillator 8, the conductive member 7 extending in the circumferential direction of the valve.
Since the valve is provided, the distance from the center of the valve becomes uniform everywhere in the circumferential direction. Therefore, even if the cold cathode 2b deviates from the center of the bulb due to deformation due to vibration or shock during or after manufacture, the conductive member 7 exists in the deviating direction, so The distance between the cathode 2b and the conductive member 7 does not increase. Therefore, the distance between the cold cathode 2b and the conductive member 7 can be set to be equal to or less than a certain distance, so that the variation in the starting voltage among the lamps is reduced and the starting is stabilized.

In the above embodiment, the conductive member 7 is
Since it is formed at a position overlapping with the electrode body 21 of the one cold cathode 2b adjacent thereto in a side view, the conductive member 7 and the cold cathode 2b can be installed in the shortest distance,
Easy starting.

Furthermore, since the conductive member 7 is formed over 270 ° along the circumferential direction of the bulb 1, even if the cold cathode 2b is deviated from the center of the bulb in any direction, the cold cathode 2b and the conductive member 7 will not be displaced. The distance of 7 can be set within a certain range. Of course, it is desirable that the conductive member 7 is continuously provided on the entire circumference of the bulb 1.

Since the conductive member 7 is formed of a conductive adhesive tape, it can be easily formed on the outer surface of the valve. Since the outer surfaces of the conductive member 7 and the auxiliary electrode 6 are insulated by applying a transparent insulating tape or the like, it is possible to prevent problems such as short-circuiting by touching a conductive member in the vicinity or electric shock during assembly work. To be done.

The rare gas discharge lamp as described above can be combined with a reflector to form an illuminating device. Such an illumination device can be applied to the image reading device shown in FIG. That is, in the image reading apparatus of FIG.
Is a rare gas discharge lamp having the structure shown in FIG. 1, and 31 is a reflector. The reflector 31 is formed by pressing an aluminum plate, for example, and its cross section is close to an elliptical partial shape, that is, approximately a U shape, and is a long shape along the bulb axis of the rare gas discharge lamp 30. The whole is almost gutter-shaped. The rare gas discharge lamp 30 has the reflector 3
1, the light emitted from the lamp 30 is reflected by the reflector 31, and the glass plate 3 for placing the document is placed.
The light is focused on two fixed positions. A read original 33 is placed on the original placing glass plate 32, and the lower surface of the original 33 is illuminated by the above-mentioned light collection. Then, the reflected light is imaged on the photoelectric conversion element 35 by the optical imaging lens system 34 provided below. Therefore, the original 33 is illuminated by the light emitted from the rare gas discharge lamp 30.
The image described in (1) is read by the photoelectric conversion element 35 via the optical imaging lens system 34.

The rare gas discharge lamp 30, the reflector 31, the optical imaging lens system 34, and the photoelectric conversion element 35 are integrated by a frame 36, and this integrated unit is combined with the original placing glass plate 32. It is configured to move relatively horizontally, so that the image of the read original 33 is scanned.

If the rare gas discharge lamp 30 shown in FIG. 1 is used as the light source of such an image reading apparatus, the enclosed gas pressure can be increased, so that the brightness is increased and the reading accuracy is improved. Moreover, since the auxiliary electrode 6 is provided outside the bulb, the starting performance is good, the discharge is stable, and in addition, since the conductive member 7 is provided at the tip, there is no variation in the starting.

When the rare gas discharge lamp 30 and the reflector 31 are used in combination, if the auxiliary electrode 6 attached to the bulb 1 is formed at a position opposite to the opening of the reflector 30, the front side is formed. It will not interfere with the light going to.

In the above embodiment, the auxiliary electrode 6 and the conductive member 7 are formed of a conductive adhesive tape, but in this case, it is more effective to use a conductive adhesive as the adhesive. However, the present invention is not limited to forming the auxiliary electrode 6 and the conductive member 7 with a conductive adhesive tape, and a conductive paint is applied, a conductive wire is added, a conductive foil is added, and the like. Various other structures can also be implemented. Even in the case of these modified examples, it is preferable that a transparent insulating tape or the like is attached to the outer surfaces of the conductive member 7 and the auxiliary electrode 6 for insulation treatment.

In the above embodiment, the rare gas discharge lamp of the present invention is used as the light source of the image reading apparatus, but the present invention is not limited to this, and the light source of other OA equipment,
It is also effective when applied to high mount stop lamps and rear combination lamps of vehicles. Furthermore, the electrode is not limited to the cold cathode, and may be a small hot cathode.

[0045]

As described above, according to the invention of claim 1, since the conductive member extending in the circumferential direction of the valve is provided at the tip of the auxiliary electrode, even if the internal electrode is displaced from the center of the valve, the deviation is caused. Since the conductive member exists in the lateral direction, the electrode does not move away from the conductive member. Therefore, the electrode and the conductive member can be installed at a certain distance or less, the discharge starting characteristic is stabilized, and the variation in the starting property can be reduced.

According to the second aspect of the invention, since the conductive member is formed at a position overlapping with one of the electrodes facing the conductive member in a side view, the electrode and the conductive member can be brought close to each other, and the startability is improved. improves.

According to the third aspect of the invention, since the conductive member is formed over 270 ° or more along the circumferential direction of the valve, the electrode and the conductive member are deviated in any direction from the center of the valve. Can be installed within a certain distance.

According to the invention of claim 4, since the conductive member is formed of the conductive adhesive tape, the conductive member can be easily formed on the outer surface of the valve. According to the invention of claim 5, since the conductive member is formed of the conductive foil, the conductive member can be easily formed on the outer surface of the valve.

According to the sixth aspect of the invention, since the outer surface of the conductive member is insulated, it is possible to prevent problems such as short-circuiting due to contact with the surrounding conductive member. According to the invention of claim 7, it is possible to provide a lighting device which has stable starting characteristics, stable discharge during lighting, and high brightness.

According to the eighth aspect of the present invention, it is possible to provide an image reading apparatus which has stable starting characteristics, stable discharge during lighting, high brightness, and therefore clear image reading.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (A) is a cross-sectional view of a rare gas discharge lamp, (B) is a cross-sectional view taken along the line AA in (A).

FIG. 2 is a diagram showing a configuration of an image reading apparatus using the rare gas discharge lamp of FIG. 1 as a light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bulb 2a, 2b ... Cold cathode 6 ... Auxiliary electrode 7 ... Conductive member 8 ... High frequency oscillator 31 ... Reflector 32 ... Original placement glass plate 33 ... Read original 34 ... Optical imaging lens system 35 ... Photoelectric conversion element

Claims (8)

[Claims] 1. A valve in which electrodes are sealed at both ends and a rare gas is sealed inside; a supplementary electrode arranged on the outer surface of the valve along the pipe axis direction and having one end connected to a power source; A rare gas discharge lamp, comprising: a conductive member that is provided at an end of the auxiliary electrode opposite to the power supply connection end and extends along the circumferential direction of the bulb. 2. The rare gas discharge lamp according to claim 1, wherein the conductive member is formed at a position overlapping one of the electrodes adjacent thereto in a side view. 3. The rare gas discharge lamp according to claim 1, wherein the conductive member is formed over 270 ° or more along the circumferential direction of the bulb. 4. The rare gas discharge lamp according to claim 1, wherein the conductive member is formed by bonding a conductive tape to the outer surface of the bulb. 5. The conductive member is formed by additionally mounting a conductive foil on the outer surface of the valve.
A rare gas discharge lamp according to claim 3. 6. The rare gas discharge lamp according to claim 1, wherein an outer surface of the conductive member is insulation-treated. 7. A rare gas discharge lamp according to claim 1, wherein the discharge lamp is housed and formed in a substantially gutter shape extending along the tube axis direction of the discharge lamp. And a reflector. 8. An image reading apparatus using the illuminating device.