JPS6321891Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a discharge tube used as a light source for static elimination in an electronic copying machine, and is particularly applicable to a discharge tube having a long overall length compared to the tube diameter, in the wavelength range of 800 to 1200 nm. A glass tube that can block most of the light is used, electrodes are sealed opposite each other at both ends of the glass tube, and a rare gas such as low-pressure xenon gas is filled inside the glass tube. This invention relates to a fluorescent discharge tube coated with a phosphor having a predetermined fluorescent wavelength range.

Conventional configurations and their problems Various light sources have been used for static elimination in electronic copying machines. Typical examples include a linear light source made by arranging multiple small incandescent lamps. Fluorescent lamps, EL lamps, etc. are well known.

On the other hand, looking at trends in electronic copying machines themselves, in recent years there has been a strong demand for miniaturization of the entire machine and increased copying speed.

For this reason, progress has been made in reducing the size of photosensitive drums and increasing sensitivity by using sensitizers.

Therefore, there is a need for a light source for static elimination that can keep up with the miniaturization and increased sensitivity of photosensitive drums as described above. Each of them has its own problems, and the current situation is that it has not been able to keep up with the miniaturization of electronic copying devices.

In other words, it is generally known that when a photosensitive drum is irradiated with near-infrared light, the photoreceptor becomes fatigued and the static elimination ability of the same light source decreases. This becomes a big problem when the photostatic charge removal operation is repeated. It is also known that the fatigue described above gradually recovers if the static elimination operation is stopped.

In addition, it is known that the photoreceptor of the photoreceptor drum is also affected by heat generated by infrared light generated by a light source for static elimination, and in this case, unlike the fatigue mentioned above, the photoreceptor's function deteriorates and cannot be recovered. This will cause possible problems.

The problem with the above-mentioned photosensitive drums will become more significant as the sensitivity increases as mentioned above, and for this reason, the above-mentioned small incandescent lamps are lined up to form a linear light source. Since the photosensitive drum emits a large amount of both near-infrared light and infrared light, if the sensitivity of the photosensitive drum is made high, there is a problem that it cannot be used as is.
In addition, there is a structural problem in that the brightness decreases at the connection portion of the lamp, resulting in uneven light distribution.

Therefore, recently, it has been considered to place an infrared absorbing filter between the lamp and the photosensitive drum, but the use of an infrared absorbing filter itself goes against the miniaturization of the device, and it cannot block infrared rays. However, it was not possible to eliminate the effects of heat generated by the lamp itself, and it could not be used as a light source for eliminating static electricity from highly sensitive photosensitive drums.

On the other hand, fluorescent lamps, EL lamps, etc. have been considered, but in the case of fluorescent lamps, their size is large and their brightness is too bright, so they cannot be placed close to the photosensitive drum. There are major problems with miniaturization, and in the case of EL lamps, the price is high, the brightness is insufficient, and even if the photosensitive drum becomes highly sensitive, it cannot keep up with the increase in speed. had.

Therefore, with the demand for smaller size and faster speed of electronic copying devices, the light source for static elimination is also a light source with excellent characteristics, that is, a light source that can sufficiently emit light that matches the characteristics of the photoreceptor of the photosensitive drum, as well as near-infrared, There is a strong demand for a light source that does not emit light in the infrared region, generates little heat, and has no uneven light distribution.

Purpose of the invention The present invention takes into consideration the problems with the conventional static elimination light source as described above, and aims to reduce the size of electronic copying equipment.
It is an object of the present invention to provide a novel light source that can keep up with the increase in speed, that is, that can meet the above-mentioned requirements as a light source for static elimination.

Structure of the invention The fluorescent discharge tube according to the invention uses a glass tube which has a long overall length compared to the tube diameter and can block most of the light in the wavelength range of 800 to 1200 nm, and has an anode and a cathode at both ends of the glass tube. At the same time, the inner surface of the glass tube is coated with a phosphor having a specific fluorescent wavelength range, and a rare gas such as low-pressure xenon gas is sealed inside.

DESCRIPTION OF EMBODIMENTS The fluorescent discharge tube according to the present invention will be described below with reference to the drawings, but before that, experiments conducted by the inventors will be briefly described.

The applicant of the present invention has previously proposed a light source for static elimination in Japanese Utility Model Application Publication No. 121965/1983.

The light source obtained by the above proposal is a discharge tube in which a glass tube is filled with two rod-shaped electrodes placed parallel to each other by beads and a mixed gas of xenon, neon, and argon. It is much superior to other light sources such as small lamps.

However, strictly speaking, the discharge tube has a problem in that the brightness decreases at the bead portion, making it impossible to use the discharge tube in close proximity to the photosensitive drum.

For this reason, the inventors of the present invention have conducted various studies to improve the light distribution characteristics, and have concluded that extremely favorable characteristics can be obtained by using a phosphor having a specific fluorescent wavelength range.

Based on the above-mentioned facts, the present inventors inferred that the combination of the phosphor and the light generated by glow discharge provides a light source with uniform light distribution characteristics, and then performed glow discharge with the phosphor. We also investigated the relationship with the internal gas that causes fluorescence.

At this time, the present inventors determined that the configuration as proposed above was not necessarily necessary for the formation of glow discharge,
The above study was limited to discharge tubes having electrodes at both ends of the glass tube body.

The specifications of the discharge tube used in this study are as follows: The glass tube that forms the tube body has an outer diameter of 10 mm or less, an inner diameter of 4 mm, and a wall thickness of 0.9 mm, which is small enough to be used as a light source for static elimination.
The total length was 300 mm considering the capacity of the copying machine, and after coating the inside with a phosphor whose fluorescent wavelength range was 400 to 650 mm, which included the wavelength necessary for static elimination in the electronic copying machine, as described above. Various gases are sealed at various pressures and electrodes are sealed at both ends. At this time, in order to facilitate the initiation of discharge, an emitter supplying member having an emitter was provided at the cathode for the experiment. An example of the results is shown in Figure 1 A and B.

Figure 1A shows the relationship between the discharge starting voltage, gas pressure, and type of gas when a trigger voltage of 3 to 5 kV was supplied to various discharge tubes as described above. FIG. 1B shows the illuminance of a similar discharge tube when the internal gas was set at 15 torr and the tube was discharged at various applied voltages.

It is clear from the study results shown in Figure 1 A and B above that the present inventors used xenon gas alone as the internal gas at a low pressure, for example in the range of 5 to 20 torr, and the discharge starting voltage was low. Moreover, it was found that the illuminance was bright and extremely effective. In other words, the low discharge starting voltage means that the configuration of the power supply section can be simplified and miniaturized.
Since it has an extremely important meaning for the entire electronic copying apparatus, and the light it generates is strong, it can be expected to have sufficient static elimination ability even in high-speed processing.

Next, we will examine the heat generation characteristics, light distribution characteristics, and spectroscopy of the glass tube surface when the fluorescent discharge tube used in the experiment to obtain the results shown in Figure 1, for example one filled with 6 torr of xenon gas, is discharged at 350V. When the characteristics were investigated, the results shown in Figure 2 A, B, and C were obtained.

The characteristics shown by the broken lines in Figure 2 A and B indicate that a linear light source made by arranging multiple small lamps, which has been very commonly used in the past, has a brightness comparable to that of the fluorescent discharge tube described above. This shows the characteristics when the light is turned on.

As is clear from Figures 2 (a), (b), and (c), the fluorescent discharge tube filled with 6 torr of xenon gas as described above emits light in the 450 to 600 nm range necessary for static elimination, does not generate heat, and has no uneven light distribution, and it is expected to be extremely advantageous for use as an alternative light source to conventional light sources. However, it has been found that it still has the problem that it cannot be used as a light source for static elimination of photoconductors, which have been made highly sensitive using the sensitizer mentioned at the beginning and which become fatigued and deteriorated by near-infrared and infrared light.

Therefore, the inventors of the present invention conducted various studies in order to block light in the near-infrared to infrared range in the fluorescent discharge tube as described above. It should be noted that such consideration is necessary because the use of separate components such as infrared absorption filters goes against the overall miniaturization of the electronic copying apparatus.
We investigated the structure of the fluorescent discharge tube itself, mainly the components of the glass that makes up the tube.

That is, we investigated the spectral transmission characteristics of various glasses.

An example of the results is shown in FIG.

The characteristics indicated by A in Figure 3 are the characteristics of SiO ₂ PbO, which is extremely common for light sources used in the previous experiment.
The characteristics of lead glass whose main component is Na ₂ O are shown, and the characteristics indicated by B in the figure are SiO ₂・BaO ・K ₂ O ・
It shows the characteristics of a glass whose main component is Na ₂ O and a few percent of Fe ₂ O ₃ .

As is clear from Figure 3, because lead glass is used as a light source, its transmittance is high over an extremely wide range, while glass containing Fe ₂ O ₃ has overall transmission characteristics that are lower than that of lead glass. However, there is a large difference between the transmission characteristics of light in the near-infrared to infrared region and the transmission characteristics of light in the range of 400 to 650 nm, which is necessary for removing static from the photoreceptor.

This was not developed for the purpose of using glass as a main component such as SiO ₂ mentioned above and a small amount of Fe ₂ O ₃ as a light source for lighting, where luminous efficiency would be an issue, but for use in switches etc. placed in heat generating parts. This is thought to be because glass was developed to protect parts that are sensitive to heat, that is, it was developed as a protective material against heat, and of course it is not actually used as a light source at all.

In addition, in order to investigate the cause of the appearance of the above-mentioned characteristics, as a result of mixing components of glass having characteristic B into lead glass, a similar tendency was observed when ferric oxide Fe ₂ O ₃ was included. It was found that light in the near-infrared to infrared region can be suppressed.

The intensity of the light generated by the glow discharge and the phosphor as described above and as described above is strong when considered for use in neutralizing the photosensitive drum.
In addition, considering the heat generation and light distribution characteristics, it seems possible to place the photosensitive drum extremely close to the photosensitive drum. It is assumed that the characteristic that there is a large difference between the transmittance of light in the external and infrared regions and the transmittance of the wavelength range necessary for static elimination can be fully utilized.

As a result of the above-mentioned studies, experiments, and speculations, a fluorescent discharge tube according to the present invention was created, and FIG. 4 shows a front view of one embodiment thereof.

In Figure 4, figure number 1 is, for example, a few percent of Fe ₂ O ₃ .
Contains SiO ₂ , BaO・Na ₂ O・K ₂ O as main components
The tube body is made of glass that can almost block wavelengths from 800 to 1200 nm, and 2 is for example 520 nm, which is necessary for static elimination.
A phosphor having a peak fluorescence wavelength of 3 represents a cathode sealed at one end of the glass tube 1, and holds a tungsten coil 3a positioned within the glass tube 1.

4 is an anode sealed at the other end of the glass tube 1;
Reference numeral 5 indicates a rare gas, for example, xenon gas, which is sealed inside the glass tube 1.

The tungsten coil 3a of the cathode 3 is coated with an emitter made of a mixture of oxides of Ba, Sr, and Ca, for example, in order to lower the discharge starting voltage, and this tungsten coil 3a can be called an emitter supply member.

Incidentally, if the cathode 3 does not have an emitter, the discharge starting voltage becomes high and the life of the discharge tube itself becomes short, although not described in detail, making it difficult to put it into practical use. Similarly, a getter supply member may be provided on the anode 4; in this case, it is possible to put it into practical use even without a getter, and if a getter supply member is provided, a better discharge tube can be provided. .

Incidentally, the fluorescent discharge tube as described above has a conductive paint, a transparent conductive film, or a total length depending on the method of supplying the trigger voltage, that is, whether it is supplied directly between the anode and cathode or from the surface of the envelope. Needless to say, it is necessary to form a trigger electrode such as a metal tape that is pasted with a predetermined width in the direction.

Next, the characteristics of the fluorescent discharge tube according to the present invention having the above structure will be explained using a specific example having the specifications as shown below.

Inner diameter of glass tube 1 - 4 mm, outer diameter - 6 mm, tube length - 300 mm, phosphor 2 - Zn ₂ / SiO / Mn based phosphor,
(peak fluorescence wavelength 520mm), combination of cathode 3-dimum wire and nickel wire, tungsten coil
3a - A coil of length 5 mm in which a wire with an outer diameter of 0.2 mm is wound around a core wire with an outer diameter of 1 mm, anode 4 - a combination of a composite wire and a nickel wire, a rare gas 5 - xenon gas at a gas pressure of 6 torr, as described above. The specifications of the fluorescent discharge tube according to this invention are as follows:
When a DC voltage of 350V is applied between the positive and negative electrodes via an external resistor of, for example, 15KΩ, and a trigger voltage of 3 to 5kV is supplied via a trigger electrode (not shown), a glow discharge is generated and a green light is emitted. Occur.

This is thought to be because the light generated by the glow discharge, especially the light with a wavelength of 350 nm or less in the positive column region, excites the phosphor 2, which has a peak fluorescence wavelength of 520 nm. When the distribution characteristics were investigated, the results shown in FIG. 5 were obtained.

As is clear from Figure 5, compared with the characteristics shown in Figure 2(C) when the tube body is made of conventional lead glass, the intensity of the light required for static elimination is certainly lower, but light in the wavelength range of 800 to 1200 nm, i.e., light from the near infrared to infrared regions, is almost entirely blocked.

Although the above-mentioned reduction in light intensity occurs, in actual use, as explained in Figure 2 A and B, the heat generation characteristics and light distribution characteristics are extremely excellent, so when the light is used very close to the photoreceptor. There is no problem because the intensity of the light with the characteristics shown in Figure 2 (c) for comparison is sufficiently high, and the fluorescent discharge tube according to the present invention can be highly sensitive by using a sensitizer. The resulting light source has extremely excellent characteristics as a light source for eliminating static electricity from a photoreceptor.

Furthermore, the energy consumption of the fluorescent discharge tube according to the present invention is extremely small because the light emitting operation is obtained by glow discharge.For example, in the case of the previous example, the voltage between the anode and cathode during glow discharge is 100~
110V, the current flowing is around 15mA, which is about 1.5W, but the energy consumption of conventionally commonly used small lamps is usually more than 10W, so the fluorescent discharge according to the present invention Tubes are extremely practical.

In addition, the specific example mentioned above is one filled with xenon gas, but this was only selected based on the intensity of the light obtained, and other rare gases may also be used, taking into account the static elimination ability. It goes without saying that this is possible, and that various phosphors may be used depending on the characteristics of the photoreceptor.

Effects of the Invention As described above, the present invention generates light by a glow discharge caused by a rare gas and a phosphor, and by constructing the tube body from glass containing Fe ₂ O ₃ , The present invention has the effect of providing a fluorescent discharge tube with extremely high practical value as a light source for static elimination of a highly sensitive photoreceptor by using a sensitizer that can block light in the range from the near infrared to the infrared region from the above-mentioned generated light.

[Brief explanation of the drawing]

Figure 1 A, B and Figure 2 A, B, and C are diagrams showing the results of experiments conducted by the present inventors, and Figure 3 shows the glass used in the fluorescent discharge tube according to the present invention. FIG. 4 is a front view including a partial cross section showing an embodiment of a fluorescent discharge tube according to the present invention, and FIG. 5 is a diagram showing a fluorescent discharge tube according to the present invention. The spectral characteristic diagram of one example of a discharge tube is shown, respectively. 1... Glass tube body, 2... Fluorescent material, 3... Cathode,
4... Anode, 5... Rare gas.

Claims (1)

[Scope of claims for utility model registration] (1) A light source for static elimination in an electronic copying device, which
A glass tube containing ferric oxide (Fe ₂ O _{3 )} , which has a longer overall length than the tube diameter, and a fluorescent wavelength range coated on the inner surface of the tube have a specific characteristic required for static neutralization of the photosensitive drum of the electronic copying device. A fluorescent discharge tube comprising a wavelength range phosphor, a cathode having an anode and an emitter supply member sealed at both ends of the tube, and a low-pressure rare gas sealed in the glass tube. (2) The fluorescent discharge tube according to the utility model registration claim 1, wherein the glass tube body is made of glass mainly composed of SiO ₂・BaO ・Na ₂ O ・K ₂ O and containing several % of Fe ₂ O ₃ .