JPH05144412A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To provide a fluorescent lamp which is small in temperature dependency, low in starting voltage to obtain a stable discharge, high in luminous efficiency, long in service life, and particularly suitable as a reading light source for a color-image scanner. CONSTITUTION:A phosphor 6 is coated on the inner surface of a bulb 1 10mm or less in inner diameter, and an electrode 2 covered by a bottomed cylindrical sleeve 21 and composed of a pair of filaments 22 is disposed near each end of the bulb in a manner that both the electrodes are opposed to each other. A noble gas is sealed into the bulb, which noble gas is composed of xenon and argon gases. In this fluorescent lamp, mixing proportion of xenon in the noble gas is made 3 to 50%, the total seal pressure of the noble gas is made 30 to 150Torr, and mercurry is simultaneously sealed to an extent that the component pressure of xenon at the time of lighting is made 100 times or more as high as the vapor pressure of mercurry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp used as a reading light source of an image scanner.

[0002]

2. Description of the Related Art A mercury fluorescent lamp that excites enclosed mercury and emits a fluorescent substance coated on the inner surface of a bulb by ultraviolet rays generated has excellent characteristics such as low power consumption and high luminous efficiency. Therefore, it is widely used for various purposes, and is also used as a reading light source of an image scanner. However, the light quantity of this mercury fluorescent lamp has a high temperature dependency, and at a low temperature, the light quantity extremely decreases because the vapor pressure of mercury is extremely low.
Therefore, the mercury fluorescent lamp is not suitable for an image scanner that is required to have a small temperature dependency.

Therefore, a rare gas fluorescent lamp that fills a rare gas such as xenon, xenon-neon, or xenon-argon in place of mercury and emits a phosphor mainly by the ultraviolet rays of xenon serves as a reading light source of an image scanner. Came to be used. This rare gas fluorescent lamp has little temperature dependency and can obtain a relatively stable light amount even at low temperatures.

[0004]

However, when xenon is used alone as a rare gas, it has a drawback that it is difficult to light up unless the starting voltage is increased. For this reason, the power consumption increases, and it is necessary to increase the withstand voltage of the device, which increases the size and weight of the device and increases the cost. In addition, if there is a metal part near the lamp, the electric discharge is attracted toward the metal part, which makes the electric discharge unstable.

Next, when a mixed gas of xenon-neon is used, the starting voltage can be lowered to some extent, but the unstable discharge cannot be solved. Moreover, in order to reduce the starting voltage, it is necessary to set the neon mixture ratio to 50% or more. However, if the neon mixture ratio is set to such a high value, the neon locally emits red light and a color image is obtained. It is not suitable for the reading light source of a scanner.

In a small fluorescent lamp, the hot cathode is more efficient than the cold cathode in terms of luminous efficiency (lm / m).
Since W) is good and a large brightness can be obtained, it is suitable for a color image scanner, but since the hot cathode is composed of a thin coil filament to which an emitter substance is adhered, it is weak against sputtering and spattering is difficult. The deposited substance adheres to the inner wall of the bulb, and the bulb is blackened early, resulting in a short lamp life.

For this reason, a semi-hot type electrode having a relatively high luminous efficiency in which a filament electrode is covered with a cylindrical sleeve having a bottom has come to be used. This semi-hot type electrode can prevent the blackening of the bulb to some extent because the sputtered material adheres to the inner surface of the sleeve, but recently there is a strong demand for a longer lamp life, and it is fully compatible with this. The reality is that it cannot be done.

Therefore, the present invention has been made in view of such circumstances, and an object thereof is to have a small temperature dependency, a low starting voltage, a stable discharge, a high luminous efficiency, and a lamp. It is an object of the present invention to provide a fluorescent lamp which has a long life and is particularly suitable for a reading light source of a color image scanner.

[0009]

In order to achieve the above object, the present invention provides a pair of filament electrodes coated with a phosphor on the inner surface of a bulb having an inner diameter of 10 mm or less and covered with a cylindrical sleeve with a bottom. In the fluorescent lamp in which the rare gas consisting of xenon and argon is filled, the xenon is mixed with the xenon in the vicinity of both ends of the bulb, and the mixing ratio of the xenon in the rare gas is set to 3 to 50%. Three
The pressure is set to 0 to 150 Torr, mercury is simultaneously enclosed, and the partial pressure of the xenon at the time of lighting is made 100 times or more the vapor pressure of mercury.

[0010]

[Function] Since the mixing ratio of xenon in the rare gas composed of xenon and argon is set to 3 to 50% and the total filling pressure of the rare gas is set to 30 to 150 Torr, the discharge is stabilized and the ultraviolet light of xenon is sufficiently obtained. As a result, the starting voltage also drops. Further, since mercury is enclosed at the same time, the sputtering of the semi-hot type electrode having a good luminous efficiency is effectively prevented, and the lamp life is extended. Moreover, since the partial pressure of xenon at the time of lighting is 100 times or more of the vapor pressure of the enclosed mercury, it becomes a fluorescent lamp that mainly emits by the ultraviolet rays from xenon despite the enclosed mercury, and has temperature dependence. Can be reduced.

[0011]

EXAMPLE FIG. 1 shows a fluorescent lamp having a rated input of 2.1 W and an effective light emission length of 130 mm, which is used as a reading light source of an image scanner. The bulb 1 made of soft glass has an outer diameter of 5.8 mm and a total length of 150 mm, and a pair of electrodes 2 are arranged opposite to each other at both ends of the inside. Electrode 2
Is a tungsten wire having a diameter of 22 μm wound on a double coil, and a filament 22 coated with triple carbonate as an emitter material is covered with a sleeve 21 having a bottom and made of stainless steel, and has excellent luminous efficiency. It is a semi-hot type electrode. A getter 3 impregnated with mercury is attached to the electrode 2.

The lead wire 4 made of dumet wire is the electrode 2
And extend from the ends of the bulb 1, respectively. Then, a proximity conductor 5 made of aluminum tape, which serves as a trigger at the time of starting, is attached in the axial direction of the outer surface of the valve 1, and one end of the proximity conductor 5 is connected to one lead wire 4. The phosphor 6 is coated on the inner surface of the bulb 1, but as shown in FIG. 2, there is a portion that is not coated in the axial direction over a width of 2 mm, and this portion is the aperture 7 for emitting light.

In the bulb 1, xenon and argon are enclosed as rare gases, and mercury is also enclosed at the same time.
It is enclosed so that the partial pressure of the xenon at the time of lighting is 100 times or more the vapor pressure of mercury. Here, the mixing ratio of xenon is 3 to 50%, for example, xenon is 20%, argon is 80%, and the total filling pressure of the rare gas is 30 to 150 Torr, for example, 120 Torr. When the mixing ratio of xenon is less than 3%, the amount of ultraviolet rays of xenon is small and the luminous efficiency is lowered. On the contrary, when it exceeds 50%, the discharge becomes unstable and the starting voltage cannot be lowered sufficiently. Even when the total pressure of the rare gas is less than 30 Torr, the amount of ultraviolet rays from xenon is small and the luminous efficiency is lowered. On the contrary, when it exceeds 150 Torr, the starting voltage is increased.
Further, the amount of mercury to be sealed in order to prevent the sputtering of the electrode is about 2 to 4 mg when the size of the bulb 1 is large.

In this case, the coldest spot temperature when the lamp is lit is 8
Since it is below 0 ° C, the vapor pressure of mercury is below 0.1 torr, and the partial pressure when xenon is lit is 100 vapor pressure of mercury.
More than double. Therefore, since the probability of collision of electrons with mercury is low and the amount of mercury that is excited is extremely small, the present fluorescent lamp emits light mainly due to the ultraviolet rays from xenon, but the vapor pressure of mercury is the same as that of an ordinary mercury fluorescent lamp. Is the same as.

When the fluorescent lamp is turned on with a high frequency power of 30 to 70 KHz, the starting voltage can be started at about 1.0 KV. Incidentally, the starting voltage when using xenon alone as the rare gas is about 1.1 KV. The arc discharge is extremely stable, and flicker hardly occurs. Further, even after the flashing and lighting for 30,000 times, almost no blackening of the bulb was observed, and it could be confirmed that the lamp life was longer than in the conventional case. Furthermore, since xenon and argon are used as the rare gas, red light does not emit as in the case of neon, and since the semi-hot type electrode is used, the luminous efficiency is high,
Suitable for reading light source of color image scanner.

[0016]

As described above, in the fluorescent lamp of the present invention, the mixing ratio of xenon in the rare gas composed of xenon and argon is 3 to 50%, and the total filling pressure of the rare gas is 30 to 150 Torr. Therefore, the starting voltage is low and the discharge is stable. In addition, a semi-hot type electrode is used, and since mercury is enclosed at the same time so that the partial pressure when xenon is lit is 100 times the vapor pressure of mercury or more, there is little temperature dependence and the lamp life is long. The fluorescent lamp can be made longer and suitable for a reading light source of a color image scanner.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fluorescent lamp.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Bulb 2 Electrode 21 Sleeve 22 Filament 3 Getter 4 Lead wire 5 Proximity conductor 6 Phosphor 7 Aperture

Claims (1)

[Claims] 1. A fluorescent substance is applied to the inner surface of a bulb having an inner diameter of 10 mm or less, and a pair of filament electrodes covered with a cylindrical sleeve with a bottom are arranged near both ends of the bulb so as to face each other. In the fluorescent lamp in which the rare gas is filled, the mixing ratio of xenon in the rare gas is 3 to 50%,
A fluorescent lamp characterized in that the total filling pressure of rare gas is 30 to 150 Torr, mercury is simultaneously filled, and the partial pressure of xenon at the time of lighting is 100 times or more the vapor pressure of mercury.