JP2021007902A - Ultraviolet irradiation device and method for manufacturing ultraviolet irradiation device - Google Patents

Abstract

To provide an ultraviolet irradiation device in which the sterilization performance is improved while the decrease in productivity is suppressed.SOLUTION: The ultraviolet irradiation device 1 includes a treatment chamber 21c and a light-emitting element 31 for irradiating ultraviolet toward the inside of the treatment chamber 21c, and in which the inner wall surface of the treatment chamber 21c has an ultraviolet reflection surface, and the root-mean-square wavelength of ultraviolet irradiated from the light-emitting element 31 with respect to the optical axis direction on the ultraviolet reflection surface is 1 μm or more and 70 μm or less. As a result, the reflection characteristics of the ultraviolet reflection surface can be improved, and consequently, the sterilization performance can be improved.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultraviolet irradiation device and a method for manufacturing an ultraviolet irradiation device.

Conventionally, when sterilizing with ultraviolet rays, a tube such as a mercury lamp or a xenon lamp has been used as an ultraviolet light source. Further, in recent years, due to the practical application of an LED (light emitting diode) capable of irradiating light having a wavelength capable of sterilizing, a device configuration that could not be realized when a tube is used as an ultraviolet light source. Is possible. For example, in order to use the light energy of the ultraviolet light source for sterilization more effectively, as shown in Patent Document 1 and Patent Document 2, a structure using fluororesin as a reflective material on the inner wall surface of the tubular flow path is adopted. ..

Japanese Unexamined Patent Publication No. 2018-12262 Japanese Unexamined Patent Publication No. 2018-12263

However, even if fluororesin is used as a reflective material on the inner wall surface of the flow path, the present inventors change the reflection characteristics depending on the surface texture of the reflective material itself, so that the irradiation density in the flow path decreases and sterilization occurs. It was confirmed that the performance deteriorated.
Further, in Patent Document 1 and Patent Document 2, when bubbles adhere to the inner wall surface of the flow path, the ultraviolet light is scattered by the bubbles and the intensity distribution of the ultraviolet light in the flow path changes, so this is avoided. Therefore, the surface roughness Ra of the inner wall surface of the flow path is defined. That is, when the surface roughness Ra is large, the sterilization performance is high in the state where the bubbles are attached, but the sterilization performance is not stable because it depends on the bubbles (see Patent Document 2). On the other hand, if the surface roughness Ra is small, bubbles are less likely to adhere and the sterilization performance is stable (see Patent Document 1).

Here, when the surface roughness Ra is controlled to 2 μm or less as in Patent Document 1, when a tubular member serving as a flow path is formed by a normal turning method, the cutting tool is moved at a lower speed. There is a need. Reducing the moving speed of the cutting tool in this way leads to a decrease in productivity and an increase in production cost. On the other hand, by using the extruded pipe material as the flow path, it is possible to realize the inner wall surface of the flow path having a surface roughness to which air bubbles do not easily adhere. In this case, the accuracy of the inner diameter dimension of the flow path should be improved. Is difficult and the sterilization performance is not stable.
Therefore, the present invention has been made by paying attention to a conventional unsolved problem, and it is possible to suppress a change in reflection characteristics in a flow path and improve sterilization performance while suppressing a decrease in productivity. It is an object of the present invention to provide a possible ultraviolet irradiation device and a method for manufacturing the ultraviolet irradiation device.

The ultraviolet irradiation device according to an embodiment of the present invention includes a processing chamber and a light source that irradiates ultraviolet rays toward the inside of the processing chamber, and the inner wall surface of the processing chamber has an ultraviolet reflecting surface. It is characterized in that the root mean square wavelength of the ultraviolet rays emitted from the light source on the ultraviolet reflecting surface with respect to the optical axis direction is 1 μm or more and 70 μm or less.
Further, in the method for manufacturing an ultraviolet irradiation device according to another embodiment of the present invention, ultraviolet irradiation is performed so that ultraviolet rays are irradiated from a light source provided at one end of the processing chamber toward the inside of the processing chamber. In the method for manufacturing an apparatus, in the inner wall surface of the processing chamber, at least a region from an end on the light source side to a position separated by a considerable diameter of the processing chamber in the optical axis direction of the ultraviolet rays has a feed amount. It is characterized in that it is formed by turning under the conditions of 0.03 mm / rev or more and 0.17 mm / rev or less.

According to one aspect of the present invention, it is possible to improve the irradiation density of ultraviolet rays while suppressing a decrease in productivity, and it is possible to further improve the sterilization performance of the ultraviolet irradiation device.

It is a schematic cross-sectional view which shows an example of the ultraviolet irradiation apparatus to which this invention was applied. It is explanatory drawing for demonstrating the measurement method of a parameter value. It is a characteristic diagram showing the correspondence between the root mean square wavelength Rλq and the sterilization performance (LRV) (Flow Rate: 2 L / min, bacterial species: E. Coli ATCC8739) at an LED output of 64 mW (LED wavelength 270 nm) in the ultraviolet irradiation device 1. .. The characteristic diagram showing the correspondence between the average height RSm of the element and the sterilization performance (LRV) (Flow Rate: 2 L / min, bacterial species: E. Coli ATCC8739) at the LED output of 64 mW (LED wavelength 270 nm) in the ultraviolet irradiation device 1. is there. Relationship between maximum height Rz and arithmetic mean roughness Ra and sterilization performance (LRV) at LED output 64 mW (LED wavelength 270 nm) (Flow Rate: 2 L / min, bacterial species: E. Colli ATCC8739) in the ultraviolet irradiation device 1. In the characteristic diagram for explaining, (a) shows the relationship between the maximum height Rz and the sterilization performance (LRV), and (b) shows the relationship between the arithmetic mean roughness Ra and the sterilization performance (LRV). This is an example of the optical simulation result in the processing chamber.

Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. However, the drawings are schematic, and the relationship between the thickness and the plane dimensions, the ratio of the thickness of each layer, etc. are different from the actual ones. In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, and arrangement of constituent parts. Etc. are not specified as the following. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

As a result of diligent studies and repeated experiments, the present inventors provided an ultraviolet reflecting surface on the inner wall surface of the processing chamber, and limited the root mean square wavelength of the ultraviolet reflecting surface with respect to the optical axis direction to a value of 1 μm or more and 70 μm or less. As a result, it was found that the irradiation density of ultraviolet rays can be improved while suppressing the decrease in productivity.
The ultraviolet irradiation device according to the present invention includes a processing chamber and a light source that irradiates ultraviolet rays toward the inside of the processing chamber. The inner wall surface of the processing chamber has an ultraviolet reflecting surface, and the ultraviolet source on the ultraviolet reflecting surface The root mean square wavelength of the irradiated ultraviolet rays with respect to the optical axis direction is 1 μm or more and 70 μm or less.

[Structure of UV irradiation device]
FIG. 1 is a cross-sectional view schematically showing an example of the configuration of an ultraviolet irradiation device 1 to which the present invention is applied.
The ultraviolet irradiation device 1 includes a processing chamber structure unit 2 and a light emitting unit 3.
The processing chamber structure portion 2 includes an inner cylinder 21 and a case portion 22 for accommodating the inner cylinder 21 and the light emitting unit 3.
The inner cylinder 21 is formed of an ultraviolet reflective substance. As the ultraviolet reflective substance, a fluororesin material is preferable, and it is formed of, for example, polytetrafluoroethylene PTFE. The ultraviolet reflective substance referred to here has a diffusion transmittance of 1% / 1 mm or more and 10% / 1 mm or less and a total reflectance of 70% / 1 mm or more 100 with respect to UVC light (wavelength 220 nm or more and 300 nm). % / 1 mm or less.

The inner cylinder 21 is formed in a tubular shape with both ends opened, and the hollow portion of the inner cylinder 21 constitutes a processing chamber (hereinafter, also simply referred to as a processing chamber 21c). The inner wall surface of the treatment chamber 21c is formed so as to satisfy the surface texture conditions described later. The inner cylinder 21 has a constant inner diameter, but has a large diameter portion 21a having an outer diameter larger than that of other regions in the vicinity of the central portion in the longitudinal direction. The large diameter portion 21a is formed so that when the inner cylinder 21 is housed in the case portion 22, the outer periphery of the large diameter portion 21a and the inner peripheral surface of the case portion 22 are in close contact with each other.
At positions near the end of the inner cylinder 21 on the light emitting portion 3 side, communication ports 21b are formed at six locations, for example, 60 degrees apart in the circumferential direction, facing in the radial direction and penetrating the inner cylinder 21. The placement position and number of communication ports 21b are not limited to this.
A straightening vane 23 is provided at the end of the inner cylinder 21 opposite to the light emitting portion 3 so as to close the opening.

The straightening vane 23 is formed of an ultraviolet reflecting substance such as PTFE. The rectifying plate 23 has a plurality of opening holes 23a passing between the front and back surfaces, and exerts a rectifying effect by introducing the irradiation target object into the processing chamber 21c via the rectifying plate 23, thereby varying the flow velocity of the irradiation target object. It is designed to be suppressed. Here, the irradiation target introduced into the inner cylinder 21 is rectified by providing a rectifying plate 23, but the rectifying mechanism is not limited to the rectifying plate 23 and can be rectified. Should be provided. Further, if the required bactericidal effect can be obtained, the rectifying plate 23, that is, the rectifying mechanism does not necessarily have to be provided.

A disk-shaped window 24 is provided in the opening of the inner cylinder 21 on the light emitting portion 3 side in close contact with the opening. Further, the window 24 is formed so that the outer peripheral surface of the window 24 and the inner peripheral surface of the case portion 22 are in close contact with each other when the inner cylinder 21 is housed in the case portion 22.
The window 24 is made of an ultraviolet transmissive material such as quartz glass.
The case portion 22 is made of, for example, polyolefin, specifically polypropylene or polyethylene.

The case portion 22 has a tubular shape having a circular hollow cross section, and when the inner cylinder 21 is accommodated, the inner wall surface of the case portion 22 and the outer peripheral surface of the large diameter portion 21a are in close contact with each other, and the inner cylinder 21 is also provided. The size is such that a gap is formed between the straightening vane 23 provided in the above and one end of the case portion 22, and between the window 24 and the other end of the case portion 22. An inflow portion 22a having a cylindrical hollow portion inside is formed integrally with the case portion 22 on the outer peripheral surface of the case portion 22 closer to the light emitting portion 3 side, and the case portion 22 is closer to the light emitting portion 3. On the outer peripheral surface of the above, an outflow portion 22b having a cylindrical hollow portion inside is integrally formed with the case portion 22. When the inner cylinder 21 is housed in the case portion 22, the inflow portion 22a and the outflow portion 22b are formed on both sides in the axial direction with the large diameter portion 21a of the inner cylinder 21 interposed therebetween. It is arranged at a position where it communicates with each of the gaps individually.

Therefore, when the inner cylinder 21 is housed in the case portion 22, the large diameter portion 21a of the inner cylinder 21 and the inner peripheral surface of the case portion 22 are in close contact with each other, and there are two gaps between the case portion 22 and the inner cylinder 21. Divided into compartments. Therefore, the irradiation object input from the inflow unit 22a flows into the processing chamber 21c through the rectifying plate 23 from the section formed on the rectifying plate 23 side (hereinafter referred to as the inflow side rectifying chamber 25). Then, the irradiation target in the processing chamber 21c flows out to the section formed on the window 24 side (hereinafter referred to as the outflow side rectifying chamber 26) through the communication port 21b, passes through the outflow portion 22b, and is subjected to ultraviolet rays. It is discharged to the outside of the irradiation device 1. At this time, since the large diameter portion 21a of the inner cylinder 21 and the inner peripheral surface of the case portion 22 are in close contact with each other, the inflow side rectifying chamber 25 and the outflow side rectifying chamber 26 do not communicate with each other. Further, since the outer periphery of the window 24 and the inner peripheral surface of the case portion 22 are in close contact with each other, the gap between the window 24 and the light emitting portion 3 side of the case portion 22 is maintained in watertightness.

The light emitting unit 3 includes a light emitting element 31 as a light source and a substrate 32 on which the light emitting element 31 is mounted. The light emitting element 31 is composed of, for example, a UVC-LED (deep ultraviolet LED). The light emitting portion 3 is fixed to the case portion 22 so that the light emitting surface of the light emitting element 31 faces the window 24 in the gap between the window 24 and the case portion 22. The light emitting element 31 is arranged so that the optical axis of the irradiation light from the light emitting element 31 coincides with the central axis in the longitudinal direction of the processing chamber 21c.
The light emitting element 31 is controlled by, for example, a control device (not shown).
As a result, the irradiation target input to the ultraviolet irradiation device 1 is introduced into the processing chamber 21c through the inflow portion 22a, the inflow side rectifying chamber 25, and the rectifying plate 23, and while moving in the processing chamber 21c, the light emitting element 31 After being irradiated with ultraviolet light, the light is discharged from the ultraviolet irradiation device 1 through the communication port 21b, the outflow side rectifying chamber 26, and the outflow portion 22b.

[Surface texture of the inner wall surface of the processing chamber]
Next, the surface texture of the inner wall surface of the processing chamber 21c will be described.
The processing chamber 21c of the ultraviolet irradiation device 1 according to the present embodiment is formed of an ultraviolet reflecting substance. That is, the inner wall surface of the processing chamber 21c forms an ultraviolet reflecting surface.
The inner wall surface of the treatment chamber 21c, that is, the ultraviolet ray reflecting surface, satisfies one or more conditions including at least condition (A) among the following surface texture conditions (A) to (D). It is formed.
(A) The root mean square wavelength Rλq of the irradiation light from the light emitting element 31 with respect to the optical axis direction is 1 μm or more and 70 μm or less.
(B) The average length RSm of the elements in the optical axis direction of the irradiation light from the light emitting element 31 is 140 μm or more and 400 μm or less.
(C) Arithmetic mean roughness Ra is 2 μm or more and 8 μm or less.
(D) The maximum height Rz is 2 μm or more and 53 μm or less.

The root mean square wavelength Rλq referred to here represents a value representing an average wavelength estimated from the root mean square inclination angle, and is represented by the following equation (1). Zq in the formula (1) is the root mean square of the height Z (x) at the reference length. Further, RΔq is the root mean square slope. The root mean square slope RΔq represents the root mean square of the local slope dZ / dX at the reference length. The local inclination dZ / dX is a derivative of Z (x). The 7-point formula is basically used for differentiation. Since there is not enough data within 3 points from both ends of the line, the 3-point formula and 5-point formula are used.

The average length RSm of the elements represents the average length of the contour curve elements at the reference length, and is expressed by the following equation (2). Xsi in the equation (2) is a length corresponding to one contour line element. The peaks (valleys) that make up the contour element in this case have a minimum height and a minimum length, and the height (depth) is 10% or less of the maximum height, or the length is the length of the calculation section. Those with a height of 1% or less are regarded as noise and are recognized as part of the valley (mountain) that continues before and after.

[Method of forming a treatment chamber]
The processing chamber 21c of the ultraviolet irradiation device 1 according to the present embodiment is formed by, for example, the following procedure.
In order to produce an ultraviolet reflecting surface that can satisfy the above-mentioned surface texture conditions, when the ultraviolet reflecting surface, that is, the inner wall surface of the processing chamber 21c is produced by turning, the feed amount of the cutting member is 0.03 mm /. Set the value within the range of rev or more and 0.17 mm / rev or less. By setting in this way, it is possible to realize an inner wall surface having a surface texture that can satisfy the above-mentioned condition of the surface texture, that is, an ultraviolet reflecting surface.

〔effect〕
As described above, the reflectance can be improved by producing the treatment chamber 21c so that the surface texture of the inner wall surface of the treatment chamber 21c satisfies the above-mentioned condition of the surface texture, and as a result, the sterilization performance can be improved. Can be improved. Further, at this time, the reflectance is improved by adjusting the surface texture itself of the inner wall surface of the processing chamber 21c. Therefore, as in the case of improving the reflectance by utilizing the air bubbles on the inner wall surface of the processing chamber 21c, the reflectance does not change with the passage of time, and the sterilization performance of a certain level or higher can be exhibited. it can. Further, in order for the surface texture of the ultraviolet reflecting surface to satisfy the above-mentioned surface texture condition, the feed amount of the cutting member in the turning process is set in the range of 0.03 mm / rev or more and 0.17 mm / rev or less. do it. Therefore, it is possible to form an ultraviolet reflecting surface that can satisfy the above-mentioned surface texture conditions without significantly increasing the treatment time associated with the formation of the ultraviolet reflecting surface. That is, the reflectance can be improved and the sterilization performance can be improved while suppressing the decrease in productivity.

In the above embodiment, the entire inner wall surface of the treatment chamber 21c does not have to satisfy the above-mentioned surface texture conditions. It is sufficient that the surface texture condition is satisfied only in the region of the inner wall surface of the processing chamber 21c from the end on the light emitting portion 3 side to a position separated by a corresponding diameter of the processing chamber 21c. That is, in the ultraviolet irradiation device 1, the region having the highest irradiation density for the irradiation target is a region from immediately before the light emitting element 31 to a position separated by a considerable diameter of the processing chamber 21c. Therefore, by controlling the surface texture of the ultraviolet reflecting surface so that sufficient reflection characteristics can be obtained only in the region having the highest irradiation density with respect to the irradiation target, it is possible to obtain high irradiation density and improve productivity. The equivalent diameter means "(4 times the cross-sectional area of the processing chamber 21c) / (the length of the cross-sectional circumference of the flow path)".

Further, in the above embodiment, the case where the inner cylinder 21 is formed from PTFE has been described, but the present invention is not limited to this. Since the surface texture of the fluororesin material can be considered to be equivalent to the surface texture of PTFE, even when the inner cylinder 21 is formed by using a fluororesin material different from PTFE, the surface texture is described above. If the above conditions are satisfied, the same action and effect as described above can be obtained.
Further, in the above embodiment, as shown in FIG. 1, the case where the ultraviolet irradiation device 1 includes the inflow side rectifying chamber 25 and the outflow side rectifying chamber 26 has been described, but the inflow side rectifying chamber 25 and the outflow side rectifying chamber 25 have been described. It is not necessary to have a room 26. In short, ultraviolet rays having a processing chamber 21c provided with a reflective material on the inner wall surface and emitting ultraviolet rays to an object to be irradiated from a light emitting element 31 provided at the end of the processing chamber 21c. It can be applied if it is an irradiation device.

[Detailed explanation of the effect]
Next, the effect of producing the inner cylinder 21 so as to satisfy the surface texture conditions will be described in detail.
The present inventors used the ultraviolet reflecting materials having different surface textures in the ultraviolet irradiation device 1 shown in FIG. The bactericidal performance when the Escherichia coli (ATCC8739) bacterial solution was passed through the water at 2 L / min was detected. By evaluating the sterilization performance by changing only the reflective material in the ultraviolet irradiation device 1, the reflective material characteristics can be indirectly evaluated. As described in Prior Documents 1 and 2, if air bubbles adhere to the reflective surface, the characteristics of the reflective material cannot be evaluated accurately. Therefore, at the time of evaluation, degassed water is flowed in advance to remove air bubbles on the reflective surface before sterilization evaluation. Was carried out.

The measurement of various parameters specified by the surface texture conditions was performed by the following procedure. That is, as shown in FIG. 2A, the surface texture of the ultraviolet reflecting surface was measured using a laser confocal microscope VK-X (manufactured by KEYENCE CORPORATION). The lens magnification was 10 times and the viewing angle was about 1 mm. Specifically, a cylindrical member made of PTFE corresponding to the inner cylinder 21 was divided into four equal parts by a cutting line along the axial direction, and one of them was used as a sample S1 for parameter measurement. With respect to the inner wall surface of this sample S1, that is, the surface corresponding to the ultraviolet reflecting surface, each parameter was measured at 21 points in the axial direction (FIG. 2 (b)). Regarding the root mean square wavelength Rλq, the average value of the root mean square wavelength Rλq calculated for each of the 21 points in the axial direction was taken as the root mean square wavelength Rλq of the ultraviolet reflecting surface. Similarly, the average value of the average length RSm of the elements calculated for each of the 21 points in the axial direction was taken as the average length RSm of the elements on the ultraviolet reflecting surface. Further, the average value of the arithmetic mean roughness calculated for each of the 21 locations is defined as the arithmetic average roughness Ra of the ultraviolet reflecting surface, and the average value of the maximum height Rz calculated for each of the 21 locations is the maximum height Rz of the ultraviolet reflecting surface. And said.

Then, a plurality of samples S1 having different root mean square wavelengths Rλq, a plurality of samples S1 having different average lengths RSm of elements, a plurality of samples S1 having different arithmetic mean roughness Ras, and a plurality of samples S1 having different maximum heights Rz are used. Each was prepared, and the corresponding parameters for each sample S1, that is, the root mean square wavelength Rλq, the average length RSm of the elements, the arithmetic mean roughness Ra, and the maximum height Rz were measured.

[Relationship between sterilization performance and root mean square wavelength Rλq]
FIG. 3 is a characteristic diagram showing the relationship between the root mean square wavelength Rλq and the sterilization performance with respect to the optical axis direction of the ultraviolet reflecting surface. In FIG. 3, the horizontal axis is the root mean square wavelength Rλq (μm), and the vertical axis is the sterilization performance (LRV) (Flow Rate: 2 L / min, bacterial species: E) at an LED output of 64 mW (LED wavelength 270 nm) in the ultraviolet irradiation device 1. .Coli ATCC8739). As shown in FIG. 3, the larger the root mean square wavelength Rλq, the lower the sterilization performance.

Here, in order to satisfy 99% sterilization (LRV2.0), which is a performance that can be practically used as a sterilizer in the ultraviolet irradiation device 1, the root mean square wavelength Rλq is set to 70 μm or less from FIG. It turns out that it should be done. Further, in order to satisfy 99.9% sterilization (LRV3.0), it can be seen from FIG. 3 that the root mean square wavelength Rλq should be 50 μm or less.
On the other hand, as a result of examining the processing conditions of the reflective surface, it was confirmed that the root mean square wavelength Rλq decreases as the cutting feed amount when cutting the reflective surface decreases. In order to form an ultraviolet reflecting surface where the root mean square wavelength Rλq can satisfy Rλq <1 μm, the cutting feed amount must be 0.03 mm / rev or less, and the processing process per inner cylinder 21 The time becomes long and the processing cost increases.

Therefore, the root mean square wavelength Rλq = 1 μm obtained when the turning process is performed with a feed amount that requires a relatively small decrease in productivity is set as the lower limit of the root mean square wavelength of the ultraviolet reflecting surface.
In this way, by setting the root mean square wavelength Rλq to a value within the range of 1 μm or more and 70 μm or less, it is possible to realize an ultraviolet reflecting surface having sufficient reflectance while suppressing a decrease in productivity. As a result, the sterilization performance can be improved.
Further, the surface shape shown above can be obtained by setting the feed amount at the time of cutting the reflective surface to 0.03 mm / rev or more and 0.17 mm / rev or less.

[Relationship between sterilization performance and average element length RSm]
FIG. 4 is a characteristic diagram showing the relationship between the average length RSm of the elements of the ultraviolet reflecting surface and the sterilizing performance in the reflector sample having Rλq of 1 μm or more and 70 μm or less. In FIG. 4, the horizontal axis is the average length RSm (μm) of the element, and the vertical axis is the sterilization performance (LRV) (Flow Rate: 2 L / min, bacterial species: in the ultraviolet irradiation device 1 at an LED output of 64 mW (LED wavelength 270 nm)). E. Coli ATCC8739). From the characteristic diagram of FIG. 4, it can be seen that the sterilization performance increases as the average length RSm of the elements increases. It can be seen that in the ultraviolet irradiation device 1, in order to further improve the performance and satisfy 99.9% sterilization (LRV3.0), the average length RSm of the elements needs to be 140 μm or more.

As described above, when the average length RSm of the element is 140 μm or more, high sterilization performance can be obtained when the practical light emitting element 31 is used in the ultraviolet irradiation device 1, and sterilization of LRV3.0 or more. Performance can be obtained. On the other hand, if the average length RSm of the element exceeds 400 μm, it becomes difficult to realize by cutting, and the productivity decreases. In this way, by limiting the average height RSm of the elements to a value within the range of 140 μm or more and 400 μm or less, it is possible to improve the sterilization performance while avoiding a decrease in productivity.

[Relationship between arithmetic mean roughness Ra and maximum height Rz and reflectance]
FIG. 5 shows a maximum height Rz (FIG. 5 (a)) and an arithmetic mean roughness Ra (FIG. 5 (b)) and an ultraviolet irradiation device 1 in a reflective material sample having a root mean square wavelength Rλq of 1 μm or more and 70 μm or less. It shows the relationship with the sterilization performance (LRV) (Flow Rate: 2 L / min, bacterial species: E. Coli ATCC8739) at an LED output of 64 mW (LED wavelength 270 nm).
Here, in order to satisfy 99.9% sterilization (LRV3.0) in the ultraviolet irradiation device 1, the maximum height Rz may be set to 53 μm or less from FIG. 5 (a), and arithmetic from FIG. 5 (b). It can be seen that the average roughness Ra should be 8 μm or less.
On the other hand, the smaller the maximum height Rz and the arithmetic mean roughness Ra, the longer the production time for forming the ultraviolet reflecting surface, and the higher the production cost. Therefore, the maximum height Rz = 2 μm and the arithmetic mean roughness Ra = 2 μm obtained when the ultraviolet reflecting surface is formed under the condition that the amount of decrease in productivity is relatively small, and the maximum height Rz and the arithmetic mean roughness are obtained. Let it be the lower limit of Ra.
In this way, by limiting the maximum height Rz to a value within the range of 2 μm or more and 53 μm or less or the arithmetic mean roughness Ra of 2 μm or more and 8 μm or less, the sterilization performance is improved while suppressing the increase in production cost. Can be done.

[Required control area for reflectance in the processing chamber]
FIG. 6 shows the optical simulation results in the processing chamber 21c. When the treatment chamber 21c is filled with water having a UV transmittance of 97% and the light emitting element 31 irradiates ultraviolet rays having a wavelength of 265 nm, the total reflectance is increased on the ultraviolet reflection surface made of PTFE in the treatment chamber 21c. It shows the distribution of the incident flux when it is 85%. As shown in FIG. 6, the incident flux is most in the region close to the light emitting element 31, and decreases as the distance from the light emitting element 31 increases. That is, the irradiation of ultraviolet rays in the region close to the light emitting element 31 contributes more to the object to be irradiated with ultraviolet rays. Therefore, if the reflection characteristics of the ultraviolet reflection surface in the region close to the light emitting element 31 to which the ultraviolet irradiation contributes more to the ultraviolet irradiation object are improved, the reflection characteristics in the processing chamber 21c can be efficiently improved. it can. That is, at least in the region from the light emitting element 31 to the position separated by a considerable diameter of the processing chamber 21c, the sterilization performance is improved if the surface texture of the ultraviolet reflecting surface satisfies the above conditions (A) to (D). Can be made to. Further, since the surface texture needs to be controlled only for the region near the light emitting element 31 instead of the entire inner wall surface of the processing chamber 21c, the processing time required for the turning process for forming the ultraviolet reflecting surface can be shortened accordingly. That is, productivity can be increased.

It should be noted that the scope of the present invention is not limited to the illustrated and described exemplary embodiments, but also includes all embodiments that provide an effect equal to that of the object of the present invention.
Furthermore, the scope of the present invention is not limited to the combination of the features of the invention defined by the claims, but may be defined by any desired combination of the specific features of all the disclosed features.

1 Ultraviolet irradiation device 2 Processing chamber structure 3 Light emitting unit 21 Inner cylinder 21a Large diameter portion 21b Communication port 21c Processing chamber 22 Case unit 23 Rectifier plate 24 Window 25 Inflow side rectifier chamber 26 Outflow side rectifier chamber 31 Light emitting element 32 Substrate

Claims (9)

With the processing room
It is equipped with a light source that irradiates the inside of the processing chamber with ultraviolet rays.
An ultraviolet irradiation device having an ultraviolet reflecting surface on the inner wall surface of the processing chamber, and having a root mean square wavelength of the ultraviolet rays emitted from the light source on the ultraviolet reflecting surface in the optical axis direction of 1 μm or more and 70 μm or less. The ultraviolet irradiation device according to claim 1, wherein the average length of the elements in the optical axis direction on the ultraviolet reflecting surface is 140 μm or more and 400 μm or less. The ultraviolet irradiation device according to claim 1 or 2, wherein the arithmetic mean roughness on the ultraviolet reflecting surface is 2 μm or more and 8 μm or less. The ultraviolet irradiation device according to any one of claims 1 to 3, wherein the maximum height of the ultraviolet reflecting surface is 2 μm or more and 53 μm or less. The ultraviolet reflecting surface is formed in a region of the inner wall surface from an end on the light source side to a position separated in the optical axis direction by a considerable diameter of the processing chamber, according to claims 1 to 4. The ultraviolet irradiation device according to any one item. An inflow portion that allows an irradiation object to be irradiated with ultraviolet rays to flow into the processing chamber,
The ultraviolet irradiation device according to any one of claims 1 to 5, further comprising an outflow portion for flowing out the irradiation object from the processing chamber. The ultraviolet irradiation device according to any one of claims 1 to 6, wherein the ultraviolet reflecting surface is made of a fluororesin material. The ultraviolet irradiation device according to claim 7, wherein the fluororesin material is polytetrafluoroethylene (PTFE). It is a method of manufacturing an ultraviolet irradiation device in which an ultraviolet ray is irradiated from a light source provided at one end of the processing chamber toward the inside of the processing chamber.
Of the inner wall surface of the processing chamber, at least a region from the end on the light source side to a position separated by a considerable diameter of the processing chamber in the optical axis direction of the ultraviolet rays has a feed amount of 0.03 mm / rev or more. A method for manufacturing an ultraviolet irradiation device formed by turning under the condition of 17 mm / rev or less.

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