JPS6252582B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sterilization method.

Conventionally, sterilization methods using germicidal lamps have been used as a sterilization method for food stores and indoors because of the low light emission output of germicidal lamps, and have not been used much for industrial production purposes.

Conventional germicidal lamps consume approximately several tens of watts of power, and even special large lamps consume approximately 200 watts of power. Yes,
At about 200W, the length of the sterilizing lamp becomes about 2 meters, and the amount of sterilizing radiation emitted per unit arc length does not increase significantly. It is not suitable as a sterilization method.

By the way, when the tube current value of a germicidal lamp is increased, the electric input per unit length of the arc increases, and as a result, the tube wall temperature rises and the mercury vapor pressure also rises. Since the strength of the mercury resonance line is relatively low in self-absorption when the mercury vapor pressure is low, this resonance line is efficiently radiated outside the tube and functions as a germicidal line. However, when the mercury vapor pressure increases beyond a certain level, the number of resonance lines emitted to the outside of the tube decreases due to self-absorption. In other words, as the tube current value increases, there is a maximum value in the amount of radiation of the resonance line to the outside of the tube. For this reason, conventional germicidal lamps use tube current values smaller than 1A/cm ² . On the other hand,
Germicidal lamps are usually filled with about 1 mmHg of a rare gas such as argon to improve lighting performance, but with such gas pressure, the electrical input to the sterilizing lamp must be increased. However, it is not used to excite mercury, but rather to excite rare gases, and the luminous efficiency of resonance line emission from mercury with respect to electrical input is low, and as a result, a powerful germicidal lamp has not yet been obtained. Therefore, high-speed sterilization using germicidal lamps has rarely been carried out in the past.

The purpose of the present invention is to provide a new sterilization method that can perform high ^- speed sterilization using a germicidal lamp. A long-arc type low-pressure mercury lamp sealed with mercury in an amount that maintains a gas pressure of 1 x 10 ^-4 to 5 x 10 ^-2 mmHg during emission is lit at a tube current density of 1 to 100 A/cm ² to emit light. The purpose is to sterilize bacteria by irradiating them with the light.

The present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of a DC lighting type low-pressure mercury lamp used in the present invention, where 1 is a 2000 Å to 3000 Å
The bulb is made of ozone-free quartz or hard glass for germicidal lamps, which transmits well. 2 is a cathode made of triated tungsten, and 3 is an anode made of tungsten.
Argon gas less than 10 ^-2 mmHg (25℃ standard),
Mercury 5 is sealed in a mercury clamp 4.

By controlling the temperature of the mercury clamp, the mercury vapor pressure during lighting and light emission can be controlled to a predetermined value without depending on the tube current value.

FIG. 2 is an explanatory diagram of the power supply device used in the present invention, in which 6 is a commercial AC power supply, 7 is a transformer, and 8
1 is a rectifier, 9 is a smoothing circuit, and 10 is a high-voltage superimposing circuit 11, which is the low-pressure mercury lamp illustrated in FIG.

In other words, the above-mentioned low-pressure mercury lamp is made to emit DC light using a DC power source, but in terms of electrode design,
The cathode is basically designed to have good electron emissivity, and the anode is designed to be strong enough to withstand the impact of large electron currents, so a high-current, low-pressure mercury lamp with a long electrode life can be obtained. Although it has the advantage of being easy to use and therefore can significantly increase the germicidal radiation output, it is more difficult to start up than conventional germicidal lamps. For example, a design example is a low-pressure mercury lamp with an electrode distance of 30 cm, a bulb inner diameter of 1.3 cm, an argon gas pressure of 0.5 x 10 ^-2 mmHg (25°C standard), a current value of 6 A, a voltage value of 45 V, and a power consumption of approximately 270 W. , the temperature of the mercury clamp is maintained at approximately 20℃, and when the lighting starts, the high voltage of the high voltage superimposition circuit is approximately
3KV was required. When the temperature of the mercury clamp is about 20° C. as described above, the mercury vapor pressure during lighting is about 2×10 ⁻³ mmHg.

However, in the above design example, the intensity of the resonance line 2537 Å, which has a sterilization function and is irradiated to an area of 1 cm square ¹ meter away, is approximately 450 × 10 ^-6 W, which is 0.1 A/cm ² compared to the conventional one.
It was found that the intensity is approximately 20 times greater than that of germicidal lamps that are turned on at temperatures below.

FIG. 3 is an explanatory diagram of the method for measuring the intensity of 2537 Å, where 12 is the irradiated surface 1 meter away from the low-pressure mercury lamp 11, and 1 cm ² centered on the center line X-X passing through the center between the electrodes. A UV intensity meter may be placed at the corner portion 12a to measure light at 2537 Å.

Similarly, in an actual sterilization effect test, it is possible to compare the sterilization rate by placing the film to be sterilized on the ^1m square area 12a in Figure 3 at the top. It was confirmed that the sterilization rate was 99.99% through irradiation. The bacterium tested was E. coli. Even if you use a conventional germicidal lamp or a high-output mercury lamp to replace it, in one second, at most,
99.9%, and when comparing the number of remaining bacteria, it can be seen that the method of the present invention is definitely 10 times better.

In the above design example, the tube current density is approximately 2.5A/ ^cm2 , but if transformer 7 is replaced with a high voltage and the tube current density is increased, an increase in output of 2537Å and an increase in sterilization effect can be achieved with certainty. However, as a low-pressure mercury lamp, the load on the tube wall is large, so at 20 A/cm ² or less, it is best to use natural air cooling to prevent bulb deterioration. At 20 A/cm ² or above, the bulb surface should be heated with a blower, etc. It is best to use forced cooling.
However, if the current value is larger than 100A/cm ² , it is difficult to cool the tube wall and cannot be put to practical use ^due to the heat resistance of the bulb.
If it is less than
It is practical to set it to 100A/cm ² .

Similarly, if the mercury pressure is less than 1×10 ⁻⁴ mmHg, a sufficient amount of germicidal radiation cannot be obtained. That is, 1~
Even if the light is lit with a large current of 100 A/cm ² , the mercury vapor pressure is too low, so the number of resonance lines generated per unit volume of the light emitting part is small, and if it is higher than 5 × 10 ^-2 mmHg,
As mentioned above, there is a drawback that self-absorption is severe and the emission efficiency of the resonance line is reduced.As a result, the pressure of mercury is preferably 1×10 ⁻⁴ mmHg to 5×10 ⁻² mmHg. As described above, since the vapor pressure is determined by controlling the temperature of the mercury clamp, the vapor pressure can be determined without depending on the tube current value.

Regarding argon gas, in order to reduce the excitation of argon molecules in the region with low mercury vapor pressure as mentioned above, a gas pressure lower than 1×10 ^-2 mmHg is preferable, and in the end, a low pressure mercury lamp with the above conditions is used. When the sterilizing wire is turned on at a current density of 1 to 100 A/cm ² , the output of the sterilizing wire increases significantly, and the sterilizing speed can be significantly increased.

As mentioned above, the present invention uses a low pressure mercury lamp of 1×10 ^-2 mm.
This low-pressure mercury lamp is designed as a long arc type using argon gas of less than Hg (25℃ standard) and mercury in an amount that maintains a gas pressure of 1 × 10 ^-4 to 5 × 10 ^-2 mmHg during lighting. Density 1~100A/
It emits light at cm ² and irradiates bacteria with this light to achieve high-speed sterilization, making it particularly suitable for industrial production purposes.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a low-pressure mercury lamp used in the present invention, Fig. 2 is an explanatory diagram of a power supply device used in the present invention, and Fig. 3 is an explanatory diagram of a method for measuring the intensity of 2537 Å. 1 is a valve, 2 is a cathode, 3 is an anode, 4 is a mercury clamp, 5 is mercury, 6 is a commercial AC power supply, 7 is a transformer, 8 is a rectifier, 9 is a smoothing circuit,
10 is a high voltage superimposition circuit, 11 is a low pressure mercury lamp, 1
3 and 19 are resistors, 14 and 17 are capacitors, 15
16 is a power source, 16 is a switch, 18 is a high voltage transformer, and 20 is a high voltage gap.

Claims (1)

[Claims] 1. Enclosed with argon gas of less than 1×10 ^-2 mmHg (25°C standard) and mercury in an amount to maintain a gas pressure of 1×10 ^-4 to 5×10 ^-2 mmHg during lighting and light emission. A sterilization method characterized by lighting a long-arc type low-pressure mercury lamp to emit light at a tube current density of 1 to 100 A/cm ² and irradiating bacteria with the emitted light to sterilize bacteria.