Translucent drum

Abstract

This product provides a translucent drum that can be used as both an air turn bar and a suction roll, and allows for even illumination by the lighting unit, making it suitable for visual inspection. [Solution] The light-transmitting drum 1 of the present invention comprises a cylindrical body 2 made of a cylindrical resin porous material 2A and a cylindrical transparent material 2B, one shaft portion 3A and the other shaft portion 3B that close off both ends of the shaft of the cylindrical body 2, and an illumination portion 5 provided on the shaft portion of the cylindrical body 2. Either or both of the one shaft portion 3A and the other shaft portion 3B have a hollow interior and shaft portion, and an air circulation groove 3Aa is formed on the closed end surface of the shaft of the cylindrical body 2, connected to the thickness portion of the porous material 2A and communicating with the hollow interior and shaft portion, and an intake and exhaust portion 4 is connected to the hollow shaft portion.

Description

Technical Field

[0001] The present invention relates to a translucent drum that can be used as an air turn bar or a suction roll, and can evenly illuminate almost the entire translucent surface without refraction or the like of the illumination of the lighting unit, and is suitable for performing an appearance inspection.

Background Art

[0002] For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-801) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2015-16979) disclose a member called an air turn bar. The air turn bar is a columnar chamber having an arc of a bending angle as a cross section, and air circulation holes are formed on the outer peripheral surface of the chamber. By pressurizing the inside of the chamber to a positive pressure, air is ejected from the air circulation holes to the outside of the chamber. The air turn bar is basically non-contact with its peripheral surface and a work such as a plate-like, sheet-like, or belt-like work, and does not rotate.

[0003] On the other hand, for example, Patent Document 3 (Japanese Patent Application Laid-Open No. 2008-273723) and Patent Document 4 (Japanese Patent Application Laid-Open No. 2021-173297) disclose a member called a suction roll. The suction roll has air circulation holes formed on the outer peripheral surface of a cylindrical chamber, and is configured to suck air into the chamber from the air circulation holes by depressurizing the inside of the chamber to a negative pressure. The suction roll is basically in contact with its peripheral surface and a work such as a plate-like, sheet-like, or belt-like work, and rotates.

[0004] Furthermore, for example, Patent Document 5 (Re-Published Patent No. 2013-164939) and Patent Document 6 (Japanese Patent Application Laid-Open No. 2016-191937) disclose a drum-shaped mask holding portion that is cylindrical, made of, for example, quartz that can transmit illumination light, and rotatable about a rotation axis (a predetermined axis). A configuration of a substrate processing apparatus is shown in which a substrate processing mask is held on the outer peripheral surface and a lighting unit that irradiates from the inside to the outside is provided.

[0005] Considering the prior art described above, air turn bars and suction rolls commonly have a chamber with air circulation holes formed on the outer surface of this chamber, while substrate processing devices have an illumination unit that irradiates from the inside outwards in a drum-shaped mask holding section. In other words, conventionally, there were no configurations in which an illumination unit was provided inside the chamber of an air turn bar or suction roll. To put it another way, there were no substrate processing devices in which an air circulation hole was formed on the outer surface of a drum-shaped mask holding section, with the inside being a chamber and the inside of the chamber being subjected to positive and negative pressure.

[0006] Incidentally, among the types of chuck devices that hold and support a workpiece by suction, there is a type called a translucent chuck device that irradiates light from the back side of the workpiece suction surface and performs contour and appearance inspection of the workpiece using the light transmitted through the workpiece suction surface. In such translucent chuck devices, it is essential that the device satisfies the requirement of light transmission.

[0007] As a device that satisfies the above-mentioned light-transmitting requirements for the contour and appearance inspection of workpieces, a light-transmitting suction chuck device has been disclosed, for example, in Patent Document 7 (Japanese Patent Application Publication No. 2016-9752). The light-transmitting suction chuck device in Patent Document 7 comprises an adsorption member made of a porous material that adsorbs an object on its surface, a planar light-emitting means that supplies planar light to the back surface of the adsorption member, and an air passage member disposed between the adsorption member and the planar light-emitting means, wherein the air passage member is made of a light-transmitting material, one surface of the air passage member is in contact with the back surface of the adsorption member, and an air suction groove is formed on the one surface of the air passage member.

[0008] In addition to the above, Patent Document 7 discloses that the main body, which has an air passage that draws air toward the porous material, is made of transparent plastic or acrylic resin, and that the thickness of the porous material is reduced to improve light transmission (although no specific thickness is described), and that the main body with the air passage is made of a transparent material.

[0009] In recent years, porous materials obtained by sintering granular resin have become increasingly popular because those made from materials such as metal or ceramic are expensive and heavy. Porous materials obtained by sintering granular resin are lighter than those made primarily from metal, and have the advantage of being inexpensive due to their lower purchase price and lower sintering temperature. Therefore, if a resin-based porous material is used in the light-transmitting suction chuck device described in Patent Document 7, it can be expected that both weight reduction and cost reduction can be achieved.

[0010] Here, by employing the porous material described in Patent Document 7 as air circulation holes on the surface of the chamber in the air turn bar described in Patent Documents 1 and 2, and the suction roll described in Patent Documents 3 and 4, and further combining this with the configuration of providing an illumination unit inside the drum described in Patent Documents 5 and 6, it should be possible to create a translucent drum in which air can be freely ejected and sucked from the outer circumference of the cylindrical chamber.

[0011] However, in Patent Document 7, since the air passage member was made of a light-transmitting material and had air suction grooves formed in it, ultimately, even if the light transmittance and transparency of the air passage member was high, subtle refraction of light occurred in the air suction grooves, and the air suction grooves appeared as shadows, causing differences in illumination. Also, for example, differences in suction force occurred between the parts where air suction grooves were formed and the parts where they were not. As a result, simply combining the conventional technology did not allow for obtaining an air turn bar with ideal light transmittance, a suction roll, or a light-transmitting drum that could be used for both. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2015-801 [Patent Document 2] Japanese Patent Publication No. 2015-16979 [Patent Document 3] Japanese Patent Publication No. 2008-273723 [Patent Document 4] Japanese Patent Publication No. 2021-173297 [Patent Document 5] Re-tabled publication No. 2013-164939 [Patent Document 6] Japanese Patent Publication No. 2016-191937 [Patent Document 7] Japanese Patent Publication No. 2016-9752 [Overview of the project] [Problems that the invention aims to solve]

[0013] The problem we are trying to solve is that even if we try to create a light-transmitting drum by combining conventional technologies, if we adopt a configuration in which an air passage member with grooves is formed on the underside of the porous material, the grooves will cast shadows, and differences in illuminance may occur due to the refraction of light, making it impossible to obtain ideal light transmission. Furthermore, there may be differences in the ability to eject and suck in air in parts depending on whether or not there are grooves. [Means for solving the problem]

[0014] To solve the above problems, the present invention provides a cylindrical body made of a cylindrical resin porous material and a cylindrical transparent material provided on the inner circumference of the porous material, one shaft portion and the other shaft portion provided so as to close each of the axial end faces of the cylindrical body, and an illumination portion provided on the shaft portion of the cylindrical body, wherein either or both of the one shaft portion and the other shaft portion are hollow inside and in the shaft portion, and an air circulation groove is formed on the closed axial end face of the cylindrical body, connecting to the thickness portion of the axial end face of the porous material of the cylindrical body and communicating with the hollow inside and in the shaft portion. [Effects of the Invention]

[0015] This invention has the advantage of enabling uniform, shadowless light transmission across almost the entire surface without creating shadows or refracting the illumination light, because there is no colorless, transparent component with partially formed air intake grooves on the inner circumference of the resin porous material. Furthermore, since the intake and exhaust are performed only on the porous material and not on the entire internal space of the cylindrical body, it exhibits excellent responsiveness to positive pressure (air ejection) and negative pressure (air intake). [Brief explanation of the drawing]

[0016] [Figure 1] (a) is a perspective view and (b) is a cross-sectional view showing a schematic configuration of a translucent drum of the present invention. [Figure 2] It is a cross-sectional view showing a schematic configuration of another translucent drum of the present invention.

Embodiments for Carrying Out the Invention

[0017] The present invention aims to provide a translucent drum that can be used as both an air turn bar and a suction roll, can transmit the light of the lighting unit as it is, and has excellent responsiveness to air ejection and suction. The translucent drum is achieved by a cylindrical resin porous material and a cylindrical transparent material provided on the inner peripheral side of the porous material, a first shaft portion and a second shaft portion provided to close both axial end faces of the cylindrical body, and a lighting unit provided on the shaft portion of the cylindrical body. Either or both of the first shaft portion and the second shaft portion are hollow inside and in the shaft portion, and an air flow groove is formed that connects to the thickness portion of the axial end face of the porous material of the cylindrical body and communicates with the hollow inside and the shaft portion with respect to the surface that closes the axial end face of the cylindrical body.

[0018] In the present invention, the reason for using a resin for the porous material is that there are no demerits such as cost, weight, and manufacturing efficiency in existing ceramic and metal porous materials, and above all, it has excellent translucency.

[0019] On the other hand, for example, a resin porous material as a plate material is obtained by sintering while pressurizing the resin. However, even when pressurized, the surface does not become flat due to heating, and there is a problem that the central portion is inevitably curved and cannot be made flat, and the plate thickness cannot be strictly controlled. When such a resin porous material is made cylindrical as a component of the drum, the center of the axis becomes concave.

[0020] To address the above-mentioned issues of deflection, curvature, and difficulty in controlling plate thickness, the present invention provides a method for creating a porous material. This involves integrally molding granular resin material into a plate of a predetermined thickness by sintering, leaving it at room temperature, heating it to 80°C to 100°C, and then plastically deforming the flat, plate-shaped porous material by sandwiching it between high-flatness plate members. The flexibility of the resin is then utilized to form a cylindrical drum.

[0021] Porous material made by sintering granular resin is unusable if it is only sintered, as it will be curved with a concave center and will not have a uniform thickness. However, by following the procedure described below, it is possible to produce the flat, cylindrical porous resin material of the present invention. First, the material is left to stand at room temperature in the curved state with an uneven thickness to release the heat generated during sintering and stabilize the curved shape. If this step is omitted and the flattening procedure described later is to be carried out immediately after sintering, the material will become a simple resin sheet with collapsed internal air bubbles and will not be usable.

[0022] After standing at room temperature, the material is heated to 80°C to 100°C. This heating is for the purpose of plastically deforming the curved porous material, and not for strengthening the bond through remelting or modifying the resin. Therefore, the heating temperature only needs to be sufficient to allow plastic deformation, and within this temperature range, the porous nature (porosity) will not be lost.

[0023] The resin referred to in this invention is a synthetic resin classified as a plastic, and most of them exhibit thermoplasticity at 80°C to 100°C. In other words, 80°C to 100°C is the temperature range in which plastic deformation is possible; below 80°C, plastic deformation (curvature correction) is difficult, and above 100°C, changes in thickness and surface area may occur.

[0024] After heating to 80°C to 100°C, the curved porous material is sandwiched between highly flat plate members and plastically deformed to flatten it. The curvature is corrected by applying pressure from between the highly flat plate members. The amount of pressure applied at this time will vary depending on the resin material and the thickness of the porous material, but it should be sufficient to correct the curvature by plastic deformation, without causing changes in thickness (becoming thinner) or cracking during the application of pressure.

[0025] Furthermore, it is desirable to use ultra-high molecular weight polyethylene (UHMWPE) as the resin for the porous material. This is because it has high impact resistance, abrasion resistance, lubricity, and chemical resistance, as well as being lightweight and having a stable chemical and physical shape. In addition, because it is milky white in color, although the illuminance may decrease depending on the thickness, if the thickness is appropriate, it can uniformly diffuse and transmit light from the lighting source throughout the entire porous material.

[0026] After obtaining a flat, plate-shaped porous material made of resin, it is cut at room temperature to the length of the shaft and circumference to obtain a cylindrical shape of a predetermined diameter, and the ends are butted together and heat-pressed to form a cylindrical porous material made of resin that constitutes the cylindrical body of the present invention. If a shadow is cast at the butted end portion, the resin can be injection-molded into a cylindrical shape, left to stand for a certain period of time, and then heated at 80°C to 100°C while pressing a molding roll against the porous material mounted on the shaft roll to flatten it.

[0027] In this invention, a transparent material is provided on the inner circumference of a cylindrical resin porous material. This transparent material may be in the form of a film or a plate, and may be in close contact with the inner surface of the porous material or may have a gap. The transparent material divides the internal space of the cylindrical body radially into an axial space and an outer circumferential space. If a gap is left, a plate of a predetermined thickness is used to suppress bending due to positive or negative pressure in the outer circumferential space. Note that "transparent" in "transparent material" means colorless and with a light transmittance of 100%.

[0028] At both ends of the cylindrical body, one shaft portion and the other shaft portion are provided so as to close each end. These one shaft portion and the other shaft portion serve as the rotational shaft when the present invention is used as a suction roll, and as the pivot shaft when the present invention is used as an air turn bar. Furthermore, they are designed to make only the outer periphery space of the axial space and outer periphery space, which are separated by a transparent material within the internal space of the cylindrical body, a space in which air can be drawn in and out.

[0029] In this explanation, we will describe a case where either one or both of the one shaft portion and the other shaft portion are configured as follows: for example, one shaft portion is configured as having a hollow interior and shaft portion, while the other shaft portion is configured as a solid shaft that closes the end face of the other shaft portion of the cylindrical body. In this explanation, the one shaft portion has a hollow interior and shaft portion, and an air circulation groove is formed which communicates with this hollow and connects to the thickness portion of the porous material of the cylindrical body.

[0030] In the porous material, the shaft end face of one shaft portion excluding the air circulation groove, the shaft end face formed by the other shaft portion, and the inner circumferential surface of the porous material formed by the transparent material are closed, allowing air to circulate between the thickness portion connected to the air circulation groove (the outer circumferential space in the cylindrical body) and the outer circumferential surface.

[0031] In other words, the present invention does not involve the intake or exhaust of air in the axial space within the cylindrical body, and more specifically, it does not involve the intake or exhaust of air from the bottom surface of the porous material. Thus, the present invention has a configuration in which only the limited space of the outer periphery of the internal space of the cylindrical body is under positive or negative pressure, and therefore exhibits excellent responsiveness to air ejection or suction.

[0032] Furthermore, a lighting unit is provided in the axial portion of the cylindrical body. In this lighting unit, multiple LEDs are regularly arranged on the circumferential surface in the axial and circumferential directions, for example in a staggered pattern, and the lighting unit can be controlled to turn on, off, or flash, and to control which angular positions in the circumferential direction the LEDs should be lit or turned off.

[0033] Furthermore, in this invention, the term "tubular" does not necessarily mean "cylindrical" when applied specifically to an air turn bar, as it does not rotate. It may be a tubular body with a circular arc of a predetermined angle and a predetermined radius at its axial end face. In this case, closing members are provided at both non-continuous circumferential ends, and these closing members, along with the aforementioned one end and the other end, and the transparent material, create a positive pressure in the axial space of the tubular body, allowing air to be injected from the surface of the porous plate.

[0034] Furthermore, in the above configuration, the present invention may form a single layer of porous material made of resin by laminating multiple sheets with different pore diameters and thicknesses. In this case, although the porous material made of resin consists of multiple sheets with different pore diameters and thicknesses, it is considered a single component in terms of its structural composition.

[0035] The reason for this is that, as described above, one of the features of the present invention is that no member that obstructs the projection of light from the lighting unit is placed on the underside of the resin "porous material". In the configuration of the present invention, the correlation between light transmission and air intake / exhaust performance with respect to the thickness of the porous material is as follows when the thickness of the porous material changes, assuming that the porous material has the "same porous properties" and the "illuminance of the lighting unit (light source) is constant".

[0036] If the porous material is thick, the connection diameter between the air circulation channel and the thick portion of the porous plate can be increased, resulting in higher intake and exhaust capacity, but reduced light transmission (illuminance). On the other hand, if the porous material is thin, the connection diameter between the air circulation channel and the thick portion of the porous material must be reduced, resulting in reduced intake and exhaust capacity, but increased light transmission (illuminance).

[0037] Incidentally, the correlation between light transmission and intake / exhaust capacity with respect to the density of the air circulation path in porous material (sparse for large pores, dense for small pores) is as follows: for porous material of the "same thickness" and with "constant illuminance of the lighting section (light source)", when the density of the air circulation path in the porous material is sparse, both intake / exhaust capacity and light transmission (illuminance) improve, while when the density of the porous material is dense, both intake / exhaust capacity and light transmission (illuminance) decrease.

[0038] Due to the above relationship, if a large surface area is required, the intake and exhaust capacity must be increased, which necessitates increasing the thickness of the porous material, thus reducing light transmission. Therefore, for example, if the thickness of the porous material on the outermost circumference of the cylindrical body is made as thin as possible, and the thickness of the porous material on the lower surface (lower layer) of the outermost circumference is increased by the necessary amount, creating a single layer, and an air circulation groove is connected to the thicker portion of the porous material, the reduction in light transmission can be kept to a minimum, and sufficient intake and exhaust capacity can be obtained.

[0039] For example, if necessary, the outermost porous material may be in the form of a sheet with a thickness of 1 mm or less. In this case, if the porous material is to be obtained by sintering granular resin, it is very difficult to limit the thickness, for example to 1 mm or less, because internal bubbles are not easily formed due to heating and pressurizing.

[0040] Furthermore, even if granular resin is sintered to obtain a sheet-like porous material of a predetermined thickness (e.g., 1 mm or less), due to the characteristics of the aforementioned resin-based porous material, it is difficult to manufacture the product in a flat state because it is prone to severe curvature (rolling).

[0041] Therefore, when obtaining a sheet-like porous material with a thickness of 1 mm or less, granular resin material is integrally molded into a plate of a predetermined thickness by sintering, left to stand at room temperature, heated to 80°C to 100°C, and plastically deformed by sandwiching it between high-flatness plate members to ensure the flatness of the plate-like porous material. Then, the surface is planed, and the planed sheet side is heated again to 80°C to 100°C, and plastically deformed by sandwiching it between high-flatness plate members to make it flat.

[0042] The plane can be a manual tool or an electric tool. When planing the surface, the side that is planed away from the base material becomes the required component. This side does not crumble into powder but remains in a stable sheet (film) form. Therefore, the side planed away from the base material is used. The extremely thin porous material obtained in this way does not lose its porous properties because it is obtained by planing the surface of a porous material that is originally made in a sheet form.

[0043] Furthermore, in order to laminate multiple sheets with different pore diameters and thicknesses into a single layer, for example, when flattening the rolled sheet-like porous material, the other porous material is laminated on top, heated at 80°C to 100°C, and then plastically deformed by sandwiching it between high-flatness plate members to form a single layer, and then formed into a cylindrical shape as described above.

[0044] By constructing a porous material by layering at least two types with different pore diameters and thicknesses in this way, in addition to the effects described above, it is possible to create a light-emitting drum that can flexibly and easily accommodate various factors such as intake and exhaust capacity, light transmission, and air intake and exhaust area. [Examples]

[0045] The following description will be given with reference to the drawings. In the embodiment shown in Figure 1, the light-transmitting drum 1 of the present invention has the following configuration, for example. 2 is a cylindrical body that constitutes the cylindrical shape of the light-transmitting drum 1, and in this example, it is cylindrical in shape and consists of a porous material 2A made of resin and a cylindrical transparent material 2B provided on the inner circumferential surface of the porous material 2A.

[0046] Porous material 2A is produced by, for example, sintering granular ultra-high molecular weight polyethylene resin to form a plate of a predetermined thickness, leaving it at room temperature, heating it to 80°C to 100°C, and plastically deforming it by sandwiching it between high-flatness plate members to create an extremely flat (almost flat) plate while maintaining its porous properties. Then, it is cut and molded to a predetermined circumference and axial length, and the circumferential ends are butted together and heat-pressed to form a cylinder. If necessary, final molding may then be performed between a roller that will serve as the axial core and a molding roller.

[0047] In this example, the transparent material 2B is fitted to the inner circumferential surface of the porous material 2A and to the opposing end faces of the shaft portion 3 (one shaft portion 3A, the other shaft portion 3B) that close the axial end face of the cylindrical body 2, with a sealing member (not shown) interposed between them. The transparent plate 2B is made of a suitable thickness and strength, and is a solid, colorless, transparent material without grooves or patterns, such as acrylic.

[0048] 3 is a shaft portion provided to close both end faces of the shaft of the cylindrical body 2. In this example, this shaft portion 3 is designated as one shaft portion 3A and the other shaft portion 3B at both ends of the shaft. In this example, for example, the one shaft portion 3A has a hollow interior and shaft portion, and an air circulation groove 3Aa is formed on the closed end face of the cylindrical body 2, connecting to the thickness portion of the porous material 2A of the cylindrical body 2 at the end face and communicating with the hollow interior and shaft portion.

[0049] Except for the outermost surface of the porous material 2A, the other end portion 3A, the other shaft portion 3B, and the transparent material 2B are closed off, excluding the air circulation groove 3Aa. As a result, exhaust or intake of air from the air circulation groove 3Aa is carried out through the numerous holes in the porous material 2A and from the outermost surface of the porous material 2A. In other words, in the transparent drum 1 of the present invention, the shaft portion space in the cylindrical body 2 is not under positive or negative pressure, and only the outer peripheral space where the porous material 2A is arranged is under positive or negative pressure.

[0050] Reference numeral 4 denotes an intake and exhaust section provided at the end of the shaft portion of one shaft portion 3A, connected in this example via, for example, a rotatable and sealable joint. This intake and exhaust section 4 is configured not to rotate even when the one shaft portion 3A, the cylindrical body 2, and the other shaft portion 3B rotate together as a single unit. In this example, rotational power is connected to the other shaft portion 3B.

[0051] Reference numeral 5 denotes a lighting unit provided on the shaft of the cylindrical body. In this example, multiple LED elements are provided in rows and columns at predetermined intervals from each other in the axial and circumferential directions, and a control board (not shown) is provided inside. In this example, the control wires and electrical wires of this lighting unit 5 are taken out from a hole 3Ba provided on the shaft of the other shaft 3B. Since the shaft space of the cylindrical body 2 is not related to positive or negative pressure, this hole 3Ba does not require sealing, but if there is concern that foreign matter may enter and obstruct light transmission, it may be rotatably sealed.

[0052] In the embodiment shown in Figure 2, the porous material 2A' consists of a dense porous material 2AA on the outermost surface (upper side in the figure) with a small average pore diameter and a thin relative plate thickness, and a coarse porous material 2AB on the inner surface (lower side) with a large average particle size and a thicker relative plate thickness.

[0053] The porous material 2AA (with a small thickness on the outermost edge) is made by, for example, sintering granular ultra-high molecular weight polyethylene resin to form a plate of a predetermined thickness, leaving it at room temperature, heating it to 80°C to 100°C, and plastically deforming it by sandwiching it between high-flatness plate members to ensure the flatness of the plate-shaped porous material. Then, the surface is planed, and the planed sheet side is heated again to 80°C to 100°C and plastically deformed by sandwiching it between high-flatness plate members to make it flat. In the case of the thin porous material 2AA, by planing it from the base porous material, the air pores are not crushed and the porous properties are not lost.

[0054] A flattened plate-shaped porous material 2AA is laminated with a plate-shaped porous material 2AB (with greater thickness on the inner circumference side) similar to the porous material 2A in Figure 1, heated at 80°C to 100°C, and plastically deformed by being sandwiched between high-flatness plate members to form a single layer. After that, it is formed into a cylindrical shape similar to the porous material 2A in Figure 1 to become porous material 2A'. In the porous material 2A' shown in Figure 2, the air circulation groove 3Aa is connected to the thicker porous material 2AB on the inner circumference side.

[0055] When the translucent drum 1 with the above configuration is applied, for example, as an air turn bar, and a camera is placed at a position spaced apart from the outermost surface of the porous material 2A (2A') to perform a visual inspection, it operates as follows: First, the translucent drum 1 is not rotated (rotated on its own axis). Then, exhaust is released from the intake / exhaust section 4, creating positive pressure in the outer peripheral space of the cylindrical body 2, and air is ejected from the outermost surface of the porous material 2A (2A'). The illumination section 5 may be fully lit, but in this case, it may be controlled to light only the necessary LED elements within the imaging range of the camera.

[0056] On the other hand, if the light-transmitting drum 1 with the above configuration is used, for example, as a suction roll, and a camera is placed at a position spaced apart from the outermost surface of the porous material 2A (2A') to perform a visual inspection, it operates as follows: First, the light-transmitting drum 1 is rotated (rotates on its own axis). Then, air is drawn in from the intake / exhaust section 4, creating negative pressure in the outer space of the cylindrical body 2, and air is drawn in from the outermost surface of the porous material 2A (2A'). The illumination section 5 may be fully lit, but in this case, it may be controlled to light only the necessary LED elements within the imaging range of the camera.

[0057] Here, we investigated the relationship between the illuminance of porous material 2A in Figure 1 and porous material 2A' in Figure 2. First, the direct brightness of the lighting unit 5 without passing through porous materials 2A and 2A' was 6800 Lx.

[0058] The porous material 2A in Figure 1 was manufactured with an average pore diameter of 5 μm and a thickness of 5 mm, and the illuminance when it was spaced a predetermined radius away from the lighting unit 5 was 840 Lx.

[0059] The porous material 2A in Figure 1 was fabricated with an average pore diameter of 80 μm and a thickness of 5 mm. When it was spaced at the same radius as above from the lighting unit 5, the illuminance was 2340 Lx.

[0060] In Figure 2, the porous material 2A' was created by laminating porous material 2AA, which had an average pore size of 5 μm and a thickness of 1 mm, and porous material 2AB, which had an average pore size of 80 μm and a thickness of 5 mm. When these materials were stacked to form a single layer, the illuminance when the material was spaced at the same radius as above from the lighting unit 5 was 1600 Lx.

[0061] Thus, with porous material 2A', the low light intensity of the dense porous material 2AA can be compensated for by reducing its thickness, and the decrease in intake and exhaust capacity caused by reducing the thickness of porous material 2AA can be compensated for by increasing the thickness of porous material 2AB and increasing the diameter of the connection port of the air circulation groove 3Aa. In other words, it is possible to adapt to the situation very flexibly depending on the combination.

[0062] As described above, the light-transmitting drum 1 of the present invention has no unnecessary components between it and the lighting unit 5, and therefore, problems such as shadows appearing in the light transmitted by the lighting unit 5 or differences in illuminance due to light refraction do not occur. Furthermore, the light-transmitting drum 1 of the present invention does not have a configuration that draws in and exhausts air from the bottom surface (inner circumferential surface) of the porous material, but rather a configuration that draws in and exhausts air only from the outer circumferential space of the cylindrical body 2 through the thickness portion of the porous material 2A, so there is no possibility of partial differences in the capacity of air ejection and suction.

[0063] In the above embodiment, the intake and exhaust section 4 is connected to one shaft section 3A, and the inside of the one shaft section 3A and the shaft section are made hollow, and an air circulation groove 3Aa is formed on the surface that closes the shaft end face of the cylindrical body 2. However, the intake and exhaust section 4 may be connected to the other shaft section 3B, or to both the one shaft section 3A and the other shaft section 3B.

[0064] Furthermore, although the above embodiment shows an example where the transparent material 2B is in close contact with the inner circumferential surface of the porous material 2A (2A'), it is not necessary for them to be in close contact as long as the inside of the cylindrical body 2 can be divided into an axial space and an outer circumferential space. Moreover, if the configuration is specialized for an air turn bar or the like, rotation (self-rotation) is not required, so the cylindrical body 2 does not need to be cylindrical. In that case, members are needed to further close both ends in the circumferential direction.

[0065] The light-transmitting drum 1 of the present invention provides excellent light-transmitting performance, and can be used as an air turn bar or a suction roll to perform highly accurate visual inspections due to its excellent light-transmitting performance. [Explanation of symbols]

[0066] 1. Translucent drum 2. Cylindrical body 2A porous material 2A' Porous material 2AA porous material 2AB porous material 2B Transparent material 3. Shaft section 3A One shaft part 3Aa Air circulation groove 3B Other shaft part 4. Intake and exhaust section 5. Lighting Section

Claims

1. A light-transmitting drum comprising a cylindrical body made of a tubular resin porous material and a tubular transparent material provided on the inner circumference of the porous material, one shaft portion and the other shaft portion provided so as to close both end faces of the shaft of the cylindrical body, and an illumination portion provided on the shaft portion of the cylindrical body, wherein either or both of the one shaft portion and the other shaft portion are hollow inside and in the shaft portion, and an air circulation groove is formed on the closed end face of the shaft of the cylindrical body, connected to the thickness portion of the porous material shaft end face of the cylindrical body, communicating with the hollow inside and in the shaft portion, and an intake and exhaust portion is connected to the hollow shaft portion.

2. The transparent drum according to claim 1, wherein the porous material made of resin in the cylindrical body is formed by laminating multiple materials with different pore diameters and thicknesses to form a single layer.

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