SURFACE TREATED METAL MEMBER, PREPARATION METHOD THEREOF AND PHOTOCONDUCTIVE MEMBER BY USE THEREOF

Abstract: A surface treated metal member comprises a metal member having unevenness with a plurality of spherical mark impressions formed on the surface.

Description: This invention relates to a surface treated metal support for a photoconductive layer for use in electrophotography. Known supports for photoconductive layers may be shaped as a plate, a cylinder or an endless belt etc and fabricated with a metal surface. The surface is often finished with a predetermined shape to prevent the generation of interference fringes and said surface may be machined by diamond cutting, or milling etc. When such a surface is formed by cutting, cutting may be impaired by the presence of surface defects, possibly caused by the presence of intervening matter used in the production of the alloy forming the support. For example, when an aluminum alloy is used for the support, hard intervening matter may exist in the aluminum structure, such as compounds of Si-Al-Fe, Fe-Al or TiB₂, etc, along with oxides of aluminum, magnesium, titanium, silicon and iron. Furthermore, blisters may be produced due to the presence of hydrogen and defects may also occur due to grain boundaries. When an electrophotographic photosensitive member is formed on a support having a surface defect, a non-uniformity in the electrical, optical and photoconductive characteristics of the film will be introduced which, in turn, may impair the quality of the image produced, possibly rendering it practically useless. Cutting operations may also introduce other problems. Inconsistences in the surface may be introduced due to the presence of cutting powder and cutting oil, therefore further steps must be taken to remove these waste materials. As an alternative method, it is known to control the flatness or surface coarseness of a surface of the support by sand blasting or shot blasting but, when using such techniques, it is not possible to control accurately shape and precision of the unevenness imparted onto the surface of the metal member. Various organic and inorganic photoconductive substances have been employed to produce photoconductive layers. For example, amorphous silicon having its free bonds modified with monovalent elements such as hydrogen or halogens, hereinafter referred to as a-Si(H,X) is a preferred material for the production of a photoconductive layer, due to its excellent photoconductivity, frictional resistance and heat resistance. In order to make a-Si(H,X) practically useful, it is fabricated from multiple layers. The uniformity on the photoconductive support is very important and, if there exist nonuniformity, the overall device may be rendered practically useless. It is known that the form of the a-Si(H,X) film is influenced greatly by the surface shape of the support. Above all, in an electrophotographic photosensitive drum, having a large area for which substantially uniform photoconductive characteristics are required, the surface condition of the support is very important and it should not include pillar-shaped structures or spherical projections. When using a tubular material of an aluminum alloy as a support, precise cutting or grinding operations must be applied to its surface. During such a process, intergranular stepped differences may be created, due to differences in stress levels received during the working process,due to differences in crystal orientation among the various types of crystal grains sectioned by grain boundaries. For example, unevenness with a depth of about 100 to 1000 Å (10Å = 1nm) may be formed on the cylinder surface or, alternatively, defects such as cracks may be formed along grain boundaries generating pillar-shaped structures or cone-shaped spherical projections at the grain boundaries, resulting in nonuniformities to the photoconductive charateristics. Furthermore, larger crystal grains do not disperse stress created during working as well as smaller crystal grains, resulting in further unevenness. Furthemore, hard spots may exist which may result in the generation of cracks and gouge-like scars during the machining process. In order to minimise the presence of intervening matter or blisters due to hydrogen gas, countermeasures have been applied to the aluminum base material of the support, thereby causing additional costs. The electrophotographic photosensitive members receive sliding friction repeatedly with a blade or fur brush etc for the removal of residual toner. Durability of the photosensitive member to this operation may be improved by increasing the hardness of the support and increasing the abrasion resistance of the surface of the photoconductive layer. For example, a very hard aluminum material is disclosed in Japanese Laid Open Patent Application No. 111046/1981. However, the use of an alloy having a high concentration of silicon tends to cause the silicon to precipitate from the alloy. According to the present invention, there is provided a surface treated metal support for a photoconductive layer for use in electrophotography, characterised in that a surface of said support has a plurality of spherical impressions distributed over the surface in such a way that their perimeters are in contact, wherein the radius of curvature R and the width D of the spherical impressions have values such that D divided by R is greater than or equal to 0.035 (0.35≦D/R ) and D is smaller than or equal to ≦ 500 micrometer. Preferable, the metal support is marked with impressions having substantially the same radius of curvature and width. Said support may be fabricated from an aluminum alloy and said alloy may, for example, comprise aluminum with crystal grains having a maximum size of 300 micrometer. An application of the surface treated metal support is in an electophotographic device, comprising a photoconductive layer on the metal support, with means for applying photo-radiation to the photoconductive layer, wherein the means for applying radiation is a laser giving rise to radiation having a spot diameter, such that the width D of the spherical impressions is less than that of the spot diameter. The width D of the marks may be 200 micrometer or less and is preferably 100 micrometer or less. The invention will now be described with way of example only, with reference to the accompanying drawings, in which: Figures 1-4 are schematic illustrations for assisting in the explanation of the shape of unevennes of the surface of the metal member. Figure 5 and figure 6 are a front view and a longtudinal sectional view, respectively, of a device for preparing the surface treated support. Figure 7 is a schematic illustration showing the device for preparing the photoconductive member, according to the glow discharge decomposition method. As shown in figure 1, the surface treated metal support 1 of the present invention comprises a plurality of spherical impressions 4 formed on the surface 2. That is, for example, rigid body true spheres 3 are permitted to free-fall from a position at a certain height from the surface 2, so as to collide against the surface 2 to form spherical mark impressions 4. Accordingly, by permitting a plurality of rigid body true spheres 3 with substantially the same diameter R' from substantially the same height h , a plurality of spherical mark impressions 4 with substantially the same radius of curvature R and the same width D can be formed on the surface 2. Fig. 2 and Fig. 3 show examples of the mark impressions formed in such cases. According to the example shown in Fig. 2, unevenness is formed by permitting a plurality of spherical bodies 3', 3,... with substantially the same diameter to fall from substantially the same height onto the surface 2' at different positions on the metal member 1', thereby forming a plurality of impressions 4', 4'... with substantially the same radius of curvature and width sparsely so that they may not be overlapped with each other. According to the example shown in Fig. 3, the height of unevenness (surface coarseness) is made smaller than the example shown in Fig. 1 by forming a plurality of impressions 4'', 4''... with substantially the same radius of curvature and width densely so that they may be overlapped with each other by permitting a plurality of spherical bodies with substantially the same diameter 3'', 3''... onto the positions on the surface 2'' of the metal member 1''. In this case, it is necessary as a matter of course to permit the spherical bodies to free-fall so that the timings for formation of the overlapping impressions 4'', 4''..., namely the timings of collision of the spherical bodies 3'', 3''... against the surface 2'' of the metal member 1'' should differ from each other. On the other hand, according to the example shown in Fig. 4, unevenness with irregular height is formed on the surface by permitting spherical bodies 3''', 3'''... with several kinds of diameters different from each other to fall from substantially the same height or different heights to form a plurality of impressions 4''', 4'''... with different radius of curvature and widths different from each other so that they may be overlapped with each other. By doing so, a plurality of spherical mark impressions with desired radius of curvature and width can be formed at a desired density on the surface of a metal member by controlling suitably the conditions such as hardnesses of the rigid body true sphere and the surface of the metal member, the radius of the rigid body true sphere, the falling height, the amount of spheres fallen, etc. Accordingly, it is possible to control freely the surface coarseness, namely the height or the pitch of unevenness such as finishing of the metal member surface to a mirror surface or a non-mirror surface by selection of the above conditions, and it is also possible to form unevenness of a desired shape depending on the purpose of use. Further, the bad surface condition of a port hole tube or a mandrel extrusion drawn Aℓ tube can be corrected by use of the method of the present invention to be finished to a desired surface condition. This is due to plastic deformation of the irregular unevenness of the surface by collision of rigid body true spheres. The base material for the surface treated metal member of the present invention may be any kind of metals depending on the purpose of use, but it is practically aluminum and aluminum alloys, stainless steels, steel irons, copper and copper alloys, and magnesium alloys. Also, the shape of the metal member may be selected as desired. For example, as the substrate (support) for electrophotographic photosensitive member, shapes such as plates, cylinders, columns, endless belts, etc., may be practically used. For the spherical bodies to be used in the present invention, there by be used, for example, various rigid body spheres made of metals such as stainless steel, aluminum, steel irons, nickel, brass, etc., ceramics, plastics, etc. Among them, rigid body spheres made of stainless steel or steel irons are preferred for the reasons of durability and low cost. The hardness of the spherical bodies may be either higher or lower than the hardness of the metal member, but it is preferably higher than the hardness of the metal member when the spherical bodies are used repeatedly. The surface treated metal member of the present invention is suitable for supports of photoconductive members such as electrophotographic photosensitive members, magnetic disc substrates for computer memories or a polygon mirror substrates for laser scanning. Also, it is most suitable as the construction member for various electrical or electronic devices finished to a flatness degree with a surface coarseness of R max = 1 µm or less, preferably R max = 0.05 µm or less by use of a means such as mirror finishing with a diamond bite, cylindrical grind finishing, lapping finishing, etc. For example, when using as a support for an electrophotographic photosensitive drum, a drawn tube obtained by further subjecting a port hole tube or a mandrel tube obtained by conventional extrusion working of an, aluminum alloy, etc. Drawing working is applied optionally with treatment such as heat treatment or tempering, and the cylinder is worked by practicing the method of the present invention by using, for example, a device with the constitution as shown in Fig. 5 (front view) and Fig. 6 (longitudinal sectional view) to prepare a support. In Fig. 5 and Fig. 6, 11 is, for example, an aluminum cylinder for preparation of a support. The surface of the cylinder 11 may be previously finished to a suitable flatness. The cylinder 11 is supported axially on a rotatory shaft 12, driven by a suitable driving means 13 such as a motor and is made rotatable substantially around the shaft core. The rotation speed is determined and controlled in view of the density of the spherical mark impressions formed and the amount of the rigid body true spheres supplied, etc. 14 is a device for permitting the rigid body true spheres (balls) 15 to free-fall, and it is constituted of a ball feeder 16 for storing and permitting the rigid body true spheres 15 to fall, a vibrator 17 for rocking the rigid body true spheres 15 so that they can fall readily from the feeder 16, a recovery tank 18 for recovering the rigid body true spheres 15 after collision against the cylinder 11, a ball delivering device 19 for transporting the rigid body true spheres recovered in the recovery tank 18 through a pipe to the feeder 16, a washing device 20 for liquid washing the rigid body true spheres 15 in the course of the delivering device 19, a reservoir 21 for supplying a washing liquid (solvent, etc.) through a nozzle, etc., to the washing device 20, and a recovery tank 22 for recovering the liquid used for washing. The amount of the rigid body true spheres free-falling from the feeder 16 may be controlled suitably by the degree of opening of the dropping port 23, the extent of rocking by means of the vibrator 17, etc. In the following, a constitutional example of the photoconductive member of the present invention is to be explained. Such a photoconductive member is constructed by providing a photosensitive layer containing, for example, an organic photoconductive material or an inorganic photoconductive material on a support. The shape of the support may be determined as desired, but, for example, when it is to be used for electrophotography it should be shaped in an endless belt or a cylinder as described above in the case of continuous high speed copying. The thickness of the support may be determined suitably so that a photoconductive member as desired may be formed, but when flexibility as the photoconductive member is demanded, it is made as thin as possible within the range so far as the function of a support can be fully exhibited. However, even in such a case, for preparation and handling of the support and further with respect to its mechanical strength, etc., it is generally made 10 µm or more. The support surface is applied with the surface treatment according to the present invention, and made a mirror surface or a nonmirror surface for the purpose of prevention of interference fringe, or alternatively applied with unevenness with a desired shape. For example, when the support surface is made a non-mirror surface or coarsened by imparting unevenness to the surface, unevenness is also formed on the photosensitive layer surface corresponding to the unevenness of the support surface, whereby phase difference will occur between the reflected lights from the support surface and from the photosensitive layer surface to form an interference fringe due to shearing interference or form an image defect due to formation of black speckles or streaks during reversal development. Such a phenomenon will appear markedly particularly when exposure is effected by a laser beam which is coherent light. In the present invention, such an interference fringe can be prevented by controlling the radius of curvature R and width D of the spherical mark impressions formed on the surface of the support. That is, when using the surface treated metal member of the present invention as the support, by making D / R 0.035 or higher, 0.5 or more of Newton rings due to shearing interference exist in each of the mark impressions, while by making D / R 0.055 or higher, 1 or more of such Newton rings exist, whereby interference fringes of the photoconductive member as the whole can be permitted to exist as dispersed in each mark impressions and thus interference can be prevented. Also, the width D of the mark impressions should desirably 500 µm or less, more preferably 200 µm or less, further preferably 100 µm or less. It is also desired to be not greater than the spot diameter of photoradiation, particularly not greater than the resolution particularly when employing laser beam. For example, when a photosensitive layer comprising an organic photoconductive member is to be provided on a support, the photosensitive layer can be separated in function into a charge generation layer and a charge transport layer. Also, between these photosensitive layers and the support, for prevention of carrier injection from the photosensitive layer to the support or for improvement of adhesion between the photosensitive layer and the support, an intermediate layer comprising, for example, an organic resin can be provided. The charge generation layer can be formed by dispersing at least one charge generation substance selected from the known compounds such as azo pigments, quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, quinacridone pigments, azulene compounds disclosed in Japanese Laid-open Patent Application No. 165263/1982, metal-free phthalocyanine pigments, phthalocyanine pigments containing metal ions, etc., in a binder resin such as polyester, polystyrene, polyvinyl butyral, polyvinyl pyrrolidone, methyl cellulose, polyacrylic acid esters, cellulose esters, etc., with the use of an organic solvent, followed by coating. The composition may be, for example, 20 to 300 parts by weight of a binder resin per 100 parts by weight of the charge generation substance. The charge generation layer should have a layer thickness desirably within the range of from 0.01 to 1.0 µm. On the other hand, the charge transport layer can be formed by dispersing a positive-hole transporting ing substance selected from the compounds having in the main chain or the side chain a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, a coronene, etc., or a nitrogen-containing cyclic compound such as indole, oxazole, isooxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, triazole or the like, or hydrazone compounds, etc., in a binder resin such as polycarbonate, polymethacrylic acid esters, polyallylate, polystyrene, polyester, polysulfone, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, etc., with the use of an organic solvent, followed by coating. The thickness of the charge transport layer is made 5 to 20 µm. The above charge generation layer and the charge transport layer can be laminated in any desired order, for example, in the order of the charge generation layer, and the charge transport layer from the support side or in the order contrary thereto. The photosensitive layer as mentioned above is not limited to those as described above but it is also possible to use a photosensitive layer employing a charge transfer complex comprising polyvinyl carbazole and trinitrofluorenone disclosed in IBM Journal of the Research and Development, January, 1971, pp. 75-89 or pyrilium type compound disclosed in U.S. Patents 4,395,183 and 4,327,169; a photosensitive layer containing an inorganic photoconductive material well known in the art such as zinc oxide or a cadmium sulfide dispersed in a resin; a vapour deposited film such as of selenium or selenium-tellurium; or a film comprising an amorphus material containing silicon atoms (a-Si(H,X)). Among them, the photoconductive member employing a film comprising a-Si(H,X) as the photosensitive layer has a construction having, for example, a charge injection preventing layer, a photosensitive layer (photoconductive layer) and a surface protective layer laminated successively on the support according to the present invention as described above. The charge injection preventing layer may be constructed of, for example, a-Si(H,X) and also contains atoms of the element belonging to the group III or the group V which is generally used as an impurity in semiconductors as the material for controlling conductivity. The layer thickness of the charge injection preventing layer should desirably be 0.01 to 10 µm, more preferably 0.05 to 8 µm, most preferably 0.07 to 5 µm. In place of the charge injection preventing layer, a barrier layer comprising an electrically insulating material such as Aℓ₂O₃, SiO₂, Si₃N₄, polycarbonate, etc., may be provided, or both of the charge injection preventing layer and the barrier layer may be used in combination. The photosensitive layer may be constituted of, for example, a-Si(H,X) and contains a substance for controlling conductivity different in kind from that used in the charge injection preventing layer, if desired. The layer thickness of the photosensitive layer may be preferably 1 to 100 µm, more preferably 1 to 80 µm, most preferably 2 to 50 µm. The surface protective layer may be constituted of, for example, SiC X , SiN X , etc., and its layer thickness is preferably 0.01 to 10 µm, more preferably 0.02 to 5 µm, most preferably 0.04 to 5 µm. In the present invention, for forming the photoconductive layer, etc., constituted of a-Si(H,X), there may be applied various vacuum deposition methods utilizing discharging phenomenon known in the art such as the glow discharge method, the sputtering method or the ion plating method. In the present invention, when a charge injection preventing layer or a photosensitive layer comprising a-Si(H,X) is formed directly on the support, the material for the support should preferably be selected from among the aluminum alloys as shown below and subjected to the surface unevenness working as described above. That is, the surface treated metal member as the support employs an aluminum alloy comprising crystal grains of aluminum as the matrix sectioned by boundary grains with their sizes (grain size as represented by the maximum length) being 300 µm at the maximum as its material, and has unevenness with a plurality spherical mark impressions on its surface. That is, if the size of crystal grain exceeds 300 µm, the stress during cutting working is poorly dispersed and a great stress is applied on one crystal grain, whereby the influence of the crystal orientation of one crystal grain is directly received to make the intergranular stepped difference undesirably greater. Also, the average value (for example, represented by the value calculated by dividing the length of the segment of line of the crystal grain existing within the segment of lines sectioned with a certain length) of the size of crystal grain (grain size represented by the maximum length) should preferably 100 µm or less, more preferably 50 µm or less, and it is preferably as small as possible. As the specific method for inhibiting the size of the crystal grains within the range as defined above, in the case of, for example, a tube obtained by extrusion and subsequent drawing working, there may be employed adequate controlling of working degree by making the contraction ratio and the drawing ratio during drawing working greater, adjustment of working degree during roll correction in the post-step thereof, and setting of the conditions with comformed working degree in the heat treatment in the final step. Thus, the size of the crystal grains contained in the aluminum alloy has been defined in the present invention, but with respect to other alloy components including the matrix aluminum, there is no particular limitation and any desired kind and composition of the components can be selected. Accordingly, the aluminum alloys of the present invention include those standardized or resistered as JIS, AA STANDARD, BS STANDARD, DIN STANDARD, or International Alloy Registration for expanding materials, cast moldings, diecast, etc., such as alloys with compositions of pure aluminum type, Aℓ-Cu type, Aℓ-Mn type, Aℓ-Si type, Aℓ-Mg type, Aℓ-Mg-Si type, Aℓ-Zn-Mg type, etc.; Aℓ-Cu-Mg type (duralumin, ultra-duralumin, etc.), Aℓ-Cu-Si type (Lautal) Aℓ-Cu-Ni-Mg type (Y alloy, RR alloy, etc.), sintered aluminum alloy (SAP), etc. In the present invention, the composition of the aluminum alloy may be selected suitably with considerations about the characteristics corresponding to the purpose of use such as mechanical strength, corrosion resistance, workability, heat resistance, dimensional precision, etc. Also, in aluminum alloys for general purpose, there generally exists precipitates or intervening matters caused by the alloy component positively added if desired or impurities entrained inevitably in the process of refining, ingotting, etc., and such matters may grow abnormally at grain boundaries, etc., form hard portions called as hard spot within the alloy structure, impair workability during precise working or become causes for deteriorating the characteristics of electronic parts obtained by precise working thereof. As described above, for example, silicon can form a solid solution with aluminum with difficulty and intervenes as Si, SiO₂, Aℓ-Si compounds, Aℓ-Fe-Si compounds or Aℓ-Si-Mg compounds while Aℓ as Aℓ₂O₃ in the aluminum structure in the form of, for example, islands. Also, Fe, Ti, etc., will appear as oxides in the form of hard grain boundary precipitates or hard spots. Particularly, Si can form a solid solution with Aℓ with difficulty even if contained at a low level of less than 0.5 weight % and is hard (particularly, SiO₂) and therefore, although contributing greatly to improvement of physical characteristics of Aℓ alloys, it may be caught with a working tool during surface treatment finishing, whereby surface defects may be formed. Accordingly, in the aluminum alloy of the present invention, the size of various intervening matters as mentioned above (grain size represented by the maximum length of the intervening matter grains) should desirably be made 10 µm or less, more preferably 5 µm or less. More preferably, it is desirable to use an aluminum alloy in which the size of the above intervening matter is 10 µm or less and the content of silicon is less than 0.5 weight %, or an aluminum alloy in which the size of the above intervening matter is 10 µm or less, the content of silicon is 0.5 to 7 weight %, and having a Vickers hardness of 50 Hv to 100 Hv. As the specific method for inhibiting the size of the intervening matters in the aluminum alloy to 10 µm or less, for example, there may be employed the method in which a ceramic filter with small opening sizes is used during melting of the aluminum alloy and the filter effect is fully exibited under careful management, utilizing specifically the lot after the filter has been clogged to some extent. Further, there may be also employed a counter measure against entrainment of the melt furnace material or increase in facing thickness of the slug. Further, for example, when mirror-finishing cutting working, etc., is accompanied during precise working, the cutting characteristics of the aluminum alloy can be improved by permitting magnesium and copper to coexist in the aluminum alloy. The content of magnesium or copper may be preferably each within the range from 0.5 to 10 weight %, particularly from 1 to 7 weight %. If the magnesium content is too high, intercrystalline corrosion is liable to occur, and therefore it is not desirable to add magnesium in excess of 10 weight %. Also, iron contained in the aluminum alloy will form intermetallic compounds with coexisting aluminum or silicon of the Fe-Aℓ type or the Fe-Aℓ-Si type, which will appear as the hard spots in the aluminum matrix. Particularly, the hard spots will be increased abruptly when iron content is increased higher than the critical level of 2000 ppm, and may have bad influences during, for example, mirror-finishing cutting working. Accordingly, preferable content of iron in the aluminum alloy of the present invention is 2000 ppm or less, more preferably 1000 ppm or less. Further, hydrogen contained in the aluminum alloy may give rise to structure abnormality such as blister, impair workability during precise working or cause deterioration of the characteristics of the electronic parts obtained by precise working thereof. Such inconveniences can be cancelled by inhibiting the hydrogen content in the aluminum alloy to 1.0 cc or lower, more preferably 0.7 cc or lower, per 100 g of aluminum. As the specific method for inhibiting the content of iron contained in the aluminum alloy to 2000 ppm or less, there may be employed an aluminum bullion with high purity as a starting material, for example, one which has been subjected to repeated electrolytic refining. There may be also employed the method in which careful management is performed in the respective steps of melting and casting. As the specific method for inhibiting the hydrogen content contained in the aluminum alloy to 1.0 cc or less per 100 g of aluminum, there may be employed the method in which chlorine gas is blown into the melt as the degassing step during melting of Aℓ alloy thereby to remove H₂ existing in the alloy structure as HCl, or the method in which the melt Aℓ alloy is maintained in a vaccum furnace for a certain period of time thereby to remove H₂ gas existing in the alloy structure through diffusion into vacuum. In the following, typical examples of more preferable aluminum alloy compositions of the present invention are shown. [Aℓ-Mg type] [Alloy A] Mg 0.5 to 10 weight % Si 0.5 weight % or less Fe 0.25 weight % or less (preferably 2000 ppm or less) Cu 0.04 to 0.2 weight % Mn 0.01 to 1.0 weight % Cr 0.05 to 0.5 weight % Zn 0.03 to 0.25 weight % Ti Tr or 0.05 to 0.20 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Alloy B] Mg 0.5 to 10 weight % Si 0.5 weight % or less Fe 2000 ppm or less Cu 0.04 to 0.2 weight % Mn 0.01 to 1.0 weight % Cr 0.05 to 0.5 weight % Zn 0.03 to 0.25 weight % Ti Tr or 0.05 to 0.20 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Aℓ-Mn type] [Alloy C] Mn 0.3 to 1.5 weight % Si 0.5 weight % or less Fe 0.25 weight % or less (preferably 2000 ppm or less) Cu 0.05 to 0.3 weight % Mg 0 or 0.2 to 1.3 weight % Cr 0 or 0.1 to 0.2 weight % Zn 0.1 to 0.4 weight % Ti Tr or about 0.1 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Alloy D] Mn 0.3 to 1.5 weight % Si 0.5 weight % or less Fe 2000 ppm or less Cu 0.05 to 0.3 weight % Mg 0.2 to 1.3 weight % Cr 0 or 0.1 to 0.2 weight % Zn 0.1 to 0.4 weight % Ti Tr or about 0.1 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Aℓ-Cu type] [Alloy E] Cu 1.5 to 6.0 weight % Si 0.5 weight % or less Fe 0.25 weight % or less (preferably 2000 ppm or less) Mn 0 or 0.2 to 1.2 weight % Mg 0 or 0.2 to 1.8 weight % Cr 0 or about 0.1 weight % Zn 0.2 to 0.3 weight % Ti Tr or about 0.15 to 0.2 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Alloy F] Cu 1.5 to 6.0 weight % Si 0.5 weight % or less Fe 2000 ppm or less Mn 0 or 0.2 to 1.2 weight % Mg 0 or 0.2 to 1.8 weight % Cr 0 or about 0.1 weight % Zn 0.2 to 0.3 weight % Ti Tr or 0.15 to 0.2 weight % H₂ 1.0 cc or less based on 100 g Aℓ Aℓ substantially the balance [Pure aluminum type] [Alloy G] Mg 0.02 to 0.5 weight % Si 0.3 weight % or less Fe 2000 ppm or less Cu 0.03 to 0.1 weight % Mn 0.02 to 0.05 weight % Cr Tr Zn 0.03 to 0.1 weight % Ti Tr or 0.03 to 0.1 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Alloy H] Mg 0.02 to 0.5 weight % Si 0.3 weight % or less Fe 0.25 weight % or less (preferably 2000 ppm or less) Cu 0.03 to 0.1 weight % Mn 0.02 to 0.05 weight % Cr Tr Zn 0.03 to 0.1 weight % Ti Tr or 0.03 to 0.1 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Aℓ-Mg-Si type] [Alloy I] Mg 0.35 to 1.5 weight % Si 0.5 to 7 weight % Fe 0.25 weight % or less (preferably 2000 ppm or less) Cu 0.1 to 0.4 weight % Mn 0.03 to 0.8 weight % Cr 0.03 to 0.35 weight % Zn 0.1 to 0.25 weight % Ti Tr or about 0.10 to 0.15 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance [Alloy J] Mg 0.35 to 1.5 weight % Si 0.5 to 7 weight % Fe 2000 ppm or less Cu 0.1 to 0.4 weight % Mn 0.03 to 0.8 weight % Cr 0.03 to 0.35 weight % Zn 0.1 to 0.25 weight % Ti Tr or 0.1 to 0.15 weight % H₂ 1.0 cc or less based on 100 g of Aℓ Aℓ substantially the balance (The above Tr means the trace amount when the component is not positively added). The aluminum alloy according to the present invention is subjected to plastic working such as rolling, extrusion, etc., then applied with precise working accompanied with the chemical or physical method such as the mechanical method of cutting or grinding or chemical etching, etc., optionalily combined with heat treatment, tempering, etc., as desired, to be formed into a shape suitable for the purpose of use. For example, in the case of forming into a tubular structural member such as a photosensitive drum for electrophotography for which strict dimensional precision is demanded, it is preferable to use a drawn tube obtained by subjecting a port hole extruded tube or a mandrel extruded tube obtained by conventional extrusion working further to cold draw working. Next, an example of the method for preparation of a photoconductive member according to the glow discharge charge decomposition method is to be explained. Fig. 7 shows a device for preparation of a photoconductive member according to the glow discharge decomposition method. The deposition chamber 1 consists of a base plate 2, a chamber wall 3 and a top plate 4 and within this deposition chamber 1 a cathode electrode 5 is provided. The support 6 according to the present invention made of, for example, an aluminum alloy on which a-Si(H,X) deposited film is formed is placed at the central portion of the cathode electrode 5 and also functions as the anode electrode. For formation of a-Si(H,X) deposited film by use of this preparation device, first the inflow valve 7 for the starting gas and the leak valve 8 are closed and the discharging valve 9 is opened to evacuate the deposition chamber 1. When the reading on the vaccum gauge 10 becomes 5 x 10⁻⁶ torr, the starting gas inflow valve 7 is opened and the opening of the discharging valve 9 is controlled while watching the reading on the vaccum gauge 10 so that the pressure of the starting gas mixture by use of, for example, SiH₄ gas, Si₂H₆ gas, SiF₄ gas adjusted to a desired mixing ratio in the mass flow controller 11, within the deposition chamber 1 may become a desired value. And, after confirming that the surface temperature of the drum-shaped support 6 is set at a predetermined temperature by a heater 12, the high frequency power source 13 is set at a desired power and glow discharge is excited within the deposition chamber 1. Also, during layer formation, the drum-shaped support 6 is rotated at a constant speed by a motor 14 in order to uniformize layer formation. Thus, an a-Si deposited film can be formed on the drum-shaped support 6. The present invention is described in more detail by referring to Test examples and Examples. Test example 1 By use of a rigid body true sphere made of a SUS stainless steel with a diameter of 2 mm and a device as shown in Fig. 5 and Fig. 6, the surface of a cylinder made of an aluminum alloy (diameter 60 mm, length 298 mm) was treated to form unevenness. The relationship between the diameter R' of the true sphere, the falling height h and the radius of curvature R and the width D of the mark impressions was examined. As a result, it was confirmed that the radius of curvature R and the width D of the mark impressions could be determined by the conditions of the diameter R' of the true sphere, the falling height h and the like. It was also confirmed that the pitch of the mark impressions (density of mark impressions, also pitch of unevenness) could be controlled to a desired pitch by controlling the rotation speed, rotation number of the cylinder or the amount of the rigid body true sphere fallen. Examples 1-6, Comparative example 1 Except for controlling D / R values to those indicated in Table 1B, the surface of the cylinder made of aluminum alloy was treated in the same manner as Test example 1, and the treated product is utilized as the supporting member for the photoconductive member for electrophotography. After the surface treatment for each surface treated cylinder, the surface defects formed (gouge-like scars, cracks, streaks, etc.) were examined with naked eyes and a metal microscope. The results are shown in the Table. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 1A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 The respective photoconductive members thus obtained were placed in laser beam printer LBP-X produced by Canon Inc. to perform image formation, and overall evaluations with respect to interference fringe, black dots, image defects, etc., were conducted. The results are shown in Table 1B. For comparison, a photoconductive member was prepared by use of a cylinder made of aluminum alloy subjected to surface treatment with a diamond bite of the prior art, and overall evaluations were similarly conducted. D in the supporting members for the photoconductive members of Example 1 to 6 was all made 500 µm. Examples 7, 8 The same photoconductive members as Example 1 - 6 were prepared except for making the layer constitutions as described below. In these Examples, two photoconductive members were prepared by changing D / R of the surface of the cylinder made of aluminum alloy to 0.05 (Example 7) and 0.07 (Example 8), respectively. First, an intermediate layer with a layer thickness of 1 µm was formed by use of a coating solution having a copolymer nylon resin dissolved in a solvent. Next, a coating solution containing ε-type copper phthalocyanine and a butyral resin as the binder resin was applied on the intermediate layer to form a charge generation layer with a layer thickness of 0.15 µm followed by coating of a coating solution containing a hydrazone compound and a styrene-methyl methacrylate copolymer resin as the binder resin on the charge generation layer to form a charge transport layer with a layer thickness of 16 µm. Thus, a photoconductive member was prepared. The photoconductive members thus obtained were evaluated according to the same overall evaluation as Examples 1 - 6. As the results, both Example 7 and Example 8 were practical. Particularly, the photoconductive member of Example 8 was found to be excellent. Test example 2 By use of a rigid body true sphere made of a SUS stainless steel with a diameter of 2 mm and a device as shown in Fig. 5 and Fig. 6, the surface of a cylinder made of an Aℓ-Mg type aluminum alloy (crystal grain size: maximum 200 µm; average 50 µm) (diameter 60 mm, length 298 mm) was treated to form unevenness. The relationship between the diameter R' of the true sphere, the falling height h and the radius of curvature R and the width D of the mark impressions was examined. As a result, it was confirmed than the radius of curvature R and the width D of the mark impressions could be determined by the conditions of the diameter R' of the true sphere, the falling height h and the like. It was also confirmed that the pitch of the mark impressions (density of mark impressions, also pitch of unevenness) could be controlled to a desired pitch by controlling the rotation speed, rotation number of the cylinder or the amount of the rigid body true sphere fallen. Examples 9 - 14 Except for controlling D / R values to those indicated in Table 2B, the surface of the cylinder made of aluminum alloy was treated in the same manner as Test example 2, and the treated product was utilized as the supporting member for the photoconductive member for electrophotography. After the surface treatment for each surface treated cylinder, the surface defects formed (gouge-like scars, cracks, streaks, etc.) were examined with naked eyes and a metal microscope. The results are shown in the Table. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 2A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 The respective photoconductive members thus obtained were placed in laser beam printer LBP-X produced by Canon INC. to perform image formation, and overall evaluations with respect to interference fringe, black dots, image defects, etc., were conducted. The results are shown in Table 2B. Example No (D/R) Number of defects generated in the surface treatment step Result of overall evaluation of interference fringe, black dot and image defect (*) Example 9 (0.02) 0 X Example 10 (0.03) 0 ▵ Example 11 (0.036) 0 ○ Example 12 (0.05) 0 ○ Example 13 (0.056) 0 o ○ Example 14 (0.07) 0 o ○ Comparative Example 1 (-) numberless X (*) : X practically unusable ▵ practically unsuitable ○ practically good o ○ practically very good D in the supporting members for the photoconductive members of Examples 9 to 14 was all made 500 µm. Examples 15 - 17, Comparative examples 2, 3 On the five kinds of cylinders made of Aℓ-Mg type aluminum alloys with different crystal grains as shown in Table 3B (Mg content was all 4 weight %, Fe content was all 1000 ppm or less), the same surface treatment was applied in the same manner as Examples 9 - 14, respectively. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 3A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 Aluminum cylinder temperature 250°C Inner pressure in deposition chamber during formation of deposited film 0.3 Torr Discharging frequency 13.56 MHz Film forming speed 20 Å/sec Discharging power 0.18 W/cm² Each of the thus obtained electrophotographic photosensitive drums was placed in a 400 RE copying device produced by Canon Inc., and image formation was performed and evaluation of image defects in shape of white dots (0.3 mm  or more) was practiced. The evaluation results are shown in Table 3B. For each of the respective electrophotographic photosensitive drums of Examples 15 - 17, successive copying tests of one million sheets was further practiced under the respective environments of 23 °C/relative humidity 50 %, 30 °C/relative humidity 90 %, 5°C/relative humidity 20 %. As the result, it was confirmed to have good durability without increase of image defects, particularly defect such as white drop-out etc. Example No Size of crystal grain (average µm) Image defect (number/A3) Example 15 Max. 150 (50) 0 Example 16 Max. 300 (100) 0 Example 17 Max. 900 (300) 10 Comparative Example 2 Max.1500 (500) 40 Comparative Example 3 Max.3000(1000) Numberless Examples 18, 19, Comparative examples 4, 5 The same cylinder made of aluminum alloy and photoconductive member as Example 15 were prepared except for using, in place of the Aℓ-Mg type aluminum alloy, a pure aluminum type and an Aℓ-Mg-Si type aluminum alloy (Fe contents are all 1000 ppm or less, H₂ content was all 1.0 cc/100 g Aℓ or less). The image defects when performing image formation for the cylinders thus obtained were evaluated similarly as Example 9, and the results are shown in Table 4B. Example No Size of crystal grain (average µm) Image defect (number/A3) Example 18 (pure Aℓ type) Max. 300 (100) 0 Comparative Example 4 (pure Aℓ type) Max. 900 (300) 30 Example 19 (Aℓ-Mg-Si type) Max. 300 (100) 0 Comparative Example 5 (Aℓ-Mg-Si type) Max. 900 (300) 35 Test example 3 By use of a rigid body true sphere made of a SUS stainless steel with a diameter of 2 mm and a device as shown in Fig. 5 and Fig. 6, the surface of a cylinder made of an Aℓ-Mg type aluminum alloy with the size of the impurity being 3 µm at its maximum (diameter 60 mm, length 298 mm; Si content less than 0.5 wt. %, Mg content 4 wt. %, Fe content 1000 ppm or less) was treated to form unevenness. The relationship between the diameter R' of the true sphere, the falling height h and the radius of curvature R and the width D of the mark impressions was examined. As a result, it was confirmed that the radius of curvature R and the width D of the mark impressions could be determined by the conditions of the diameter R' of the true sphere, the falling height h and the like. It was also confirmed that the pitch of the mark impressions (density of mark impression, also pitch of unevenness) could be controlled to a desired pitch by controlling the rotation speed, rotation number of the cylinder or the amount of the rigid body true sphere fallen. Examples 20 - 25 Except for controlling D / R values to those indicated in Table 5B, the surface of the cylinder made of aluminum alloy of the same quality was treated in the same manner as Test example 3, and the treated product was utilized as the supporting member for the photoconductive member for electrophotography. After the surface treatment for each surface treated cylinder, the surface defects formed (gouge-like scars, cracks, streaks, etc.) were examined with naked eyes and a metal microscope. The results are shown in the Table. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 5A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 The respective photoconductive members thus obtained were placed in laser beam printer LBP-X produced by Canon Inc. to perform image formation, and overall evaluations with respect to interference fringe, black dots, image defects, etc., were conducted. The results are shown in Table 5B. Example No (D/R) Number of defects generated in the surface treatment step Result of overall evaluation of interference fringe, black dot and image defect (*) Example 20 (0.02) 0 X Example 21 (0.03) 0 ▵ Example 22 (0.036) 0 ○ Example 23 (0.05) 0 ○ Example 24 (0.056) 0 o ○ Example 25 (0.07) 0 o ○ Comparative Example 1 Numberless X (*) : X practically unusable ▵ practically unsuitable ○ practically good o ○ practically very good D in the supporting members for the photoconductive members of Examples 20 to 25 was all made 500 µm. Examples 26 - 28, Comparative examples 6, 7 On the five kinds of cylinders made of Aℓ-Mg type aluminum alloys with different sizes of impurities as shown in Table 6B (Si content was all less than 0.5 wt. %, Mg content was all 4 weight %, Fe content was all 1000 ppm or less), the same surface treatment was applied in the same manner as Examples 20 - 25, respectively. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 6A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 Aluminum cylinder temperature Inner pressure in deposition chamber during formation of 250°C deposited film 0.3 Torr Discharging frequency 13.56 MHz Film forming speed 20 Å/sec Discharging power 0.18 W/cm² Each of the thus obtained electrophotographic photosensitive drums was placed in a 400 RE copying device produced by Canon Inc., and image formation was performed and evaluation of image defects in shape of white dots (0.3 mm  or more) was practiced. The evaluation results are shown in Table 6B. For each of the respective electrophotographic photosensitive drums of Examples 26 - 28, successive copying tests of one million sheets were further practiced under the respective environments of 23 °C/relative humidity 50 %, 30 °C/relative humidity 90 %, 5 °C/relative humidity 20 %. As the result, it was confirmed to have good durability without increase of image defects, particularly defect such as white drop-out, etc. Examples 29 - 31, Comparative examples 8 - 10 The same cylinder made of aluminum alloy and photoconductive member as Example 20 were prepared except for using, in place of the Aℓ-Mg type aluminum alloy, an Aℓ-Mn type, Aℓ-Cu type and a pure aluminum type aluminum alloy (Fe contents are all 1000 ppm or less). The number of hard spots, the number of defects generated in the mirror finishing process and the image defects when performing image formation for the cylinders thus obtained were evaluated similarly as Example 20, and the results are shown in Table 7. Examples 32 - 35 The same cylinder made of the Aℓ-Mg type aluminum alloy and photoconductive member as Example 20 were prepared except for changing the Fe content to the values shown in Table 8. The number of hard spots, the number of defects generated in the mirror finishing process and the image defects when performing image formation for the cylinders thus obtained were evaluated similarly as Example 20, and the results are shown in Table 8. Test example 4 By use of a rigid body true sphere made of a SUS stainless steel with a diameter of 2 mm and a device as shown in Fig. 5 and Fig. 6, the surface of a cylinder made of an Aℓ-Mg-Si type aluminum alloy containing 3 wt. % of Si, having a Vickers hardness of 70 Hv, with the size of the impurity being 2 µm at its maximum (diameter 60 mm, length 298 mm; Mg content 4 wt. %, Fe content 1000 ppm or less; hydrogen content 1.0 cc or less per 100 grams of aluminum) was treated to form unevenness. The relationship between the diameter R' of the true sphere, the falling height h and the radius of curvature R and the width D of the mark impressions was examined. As a result, it was confirmed that the radius of curvature R and the width D of the mark impressions could be determined by the conditions of the diameter R' of the true sphere, the falling height h and the like. It was also confirmed that the pitch of the mark impressions (density of mark impressions, also pitch of unevenness) could be controlled to a desired pitch by controlling the rotation speed, rotation number of the cylinder or the amount of the rigid body true sphere fallen. Examples 36 - 41 Except for controlling D / R values to those indicated in Table 9B, the surface of the cylinder made of aluminum alloy of the same quality was treated in the same manner as Test example 4, and the treated product was utilized as the supporting member for the photoconductive member for electrophotography. After the surface treatment for each surface treated cylinder, the surface defects formed (gouge-like scars, cracks, streaks, etc.) were examined with naked eyes and a metal microscope. The results are shown in the Table. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 9A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 The respective photoconductive members thus obtained were placed in laser beam printer LBP-X produced by Canon Inc. to perform image formation, and overall evaluations with respect to interference fringe, black dots, image defects, etc., were conducted. The results are shown in Table 9B. Example No (D/R) Number of defects generated in the surface treatment step Result of overall evaluation of interference fringe, black dot and image defect (*) Example 36 (0.02) 0 X Example 37 (0.03) 0 ▵ Example 38 (0.036) 0 ○ Example 39 (0.05) 0 ○ Example 40 (0.056) 0 o ○ Example 41 (0.07) 0 o ○ Comparative Example 1 Numberless X (*) : X practically unusable ▵ practically unsuitable ○ practically good o ○ practically very good D in the supporting members for the photoconductive members of Examples 36 to 41 was all made 500 µm. Examples 42 - 45, Comparative examples 11 On the five kinds of cylinders made of Aℓ-Mg-Si type aluminum alloys with differences in Si content, Vickers hardness and size of impurities as shown in Table 10B (Mg content was all 4 weight %, Fe content was all 1000 ppm or less), the same surface treatment was applied in the same manner as Examples 36 - 41, respectively. Next, on these respective cylinders of aluminum alloy applied with the surface treatment, photoconductive members were prepared under the conditions shown in Table 10A by means of the preparation device of photoconductive members shown in Fig. 7 following the glow discharge decomposition method as described in detail above. Lamination order of deposited films Starting gases employed Film thickness (µm) 1 ○ Charge injection preventing layer SiH₄/B₂H₆ 0.6 2 ○ Photoconductive layer SiH₄ 20 3 ○ Surface protective layer SiH₄/C₂H₄ 0.1 Aluminum cylinder temperature Inner pressure in deposition chamber during formation of 250 °C deposited film 0.3 Torr Discharging frequency 13.56 MHz Film forming speed 20 Å/sec Discharging power 0.18 W/cm² Each of the thus obtained electrophotographic photosensitive drums was placed in a 400 RE copying device produced by Canon Inc., and image formation was performed and evaluation of image defects in shape of white dots (0.3 mm  or more) was practiced. The evaluation results are shown in Table 10B. For each of the respective electrophotographic photosensitive drums of Examples 42 - 45, successive copying tests of one million sheets were further practiced under the respective environments of 23 °C/relative humidity 50 %, 30 °C/relative humidity 90 %, 5 °C/relative humidity 20%. As the result, it was confirmed to have good durability without increase of image defects particularly defect such as white drop-out, etc. According to the present invention, the surface treatment can be done without accompaniment of cutting working which will readily give rise to the surface defects impairing the desired use characteristics, and therefore a photoconductive member excellent in uniformity of film formation, and uniformity of electrical, optical or photoconductive characteristics can be obtained. Particularly, images of high quality with little image defect can be obtained when it is used for electrophotographic photosensitive member.

Claims: A surface treated metal support (1) for a photoconductive layer for use in electrophotography, characterised in that a surface (2) of said support has a plurality of spherical impressions (4) distributed over said surface in such a way that their perimeters are in contact, wherein the radius of curvature R and a width D of the spherical impressions have values such that D divided by R is greater than or equal to 0.035 (0.035 ≦ D/R) and D is equal to or less than 500 micrometre. A metal support according to claim 1, wherein said impressions have substantially the same radius of curvature and width. A metal support according to claim 1 or claim 2, wherein said support consists of an aluminum alloy. A metal support according to claim 3, wherein said aluminum alloy comprises aluminum as the matrix and the maximum crystal grain size of the aluminum is 300 micrometre or less. A metal support according to claim 3, wherein the aluminum alloy comprises a aluminum matrix with intervening matter including silicon, said silicon being present in an amount of less than 0.5 percentage weight and the size of the intervening member being 10 micrometre or less. A metal support according to claim 3, wherein the aluminum alloy has a silicon content of 0.5 to 7 percentage weight, said support having a Vickers hardness of 50 HV to 100 HV. A metal support according to claim 4, wherein the average size of the aluminum crystal grains is 100 micrometre or less. A metal support according to claim 3, wherein the aluminum alloy contains 0.5 to 10 percentage weight of magnesium. A metal support according to claim 3, wherein the aluminum alloy contains 2000 or less parts per million of iron. A metal support according to claim 3, wherein the aluminum alloy contains 1 or less cubic centimetres of hydrogen per 100 grams of aluminum. A metal support according to claim 3, wherein the aluminum alloy contains 0.5 to 10 percentage weight of copper. A metal support according to any of one claims 1 to 11, having a photoconductive layer thereon. A metal support according to claim 11, wherein the photoconductive layer comprises an amorphous silicon. A metal support according to claim 12, wherein the photoconductive layer comprises a charge generation layer and a charge transfer layer. A metal support according to any of claims 12 to 14, further comprising an intermediate layer between the photoconductive layer and the support. A metal support according to any of claims 12 to 15, wherein the photoconductive layer comprises amorphous silicon containing hydrogen atoms and/or halogen atoms. A metal support according to claim 16, further comprising a surface protecting layer on the photoconductive layer. A metal support according to claim 17, wherein the surface protecting layer is comprised of SiC x or SiN x . A metal support according to any of claims 16 to 18, wherein the photoconductive layer comprises a charge injection preventing layer. An electrophotographic device, comprising a photoconductive layer on a surface treated metal support according to claim 1, and a laser for applying photo-radiation to the photoconductive member, wherein the width D of the spherical impressions on the surface of the metal support is less than that of the spot diameter of the radiation emitted by said laser. A device according to claim 20, wherein the width D of the spherical impressions is 200 micrometre or less. A device according to claim 20, wherein the width D of the spherical impressions is 100 micrometre or less.

Inventors: HONDA, MITSURU, MURAI, KEICHI, OGAWA, KYOSUKE, SUEDA, TETSUO
Applicants: CANON KABUSHIKI KAISHA
Application year: 1986
Main classification: G03G5
IPC codes: G03G5, B24C11, B24C1