Abstract:
A compressed wood product includes a wood whose shape is taken while a volume decreased by compression is previously added, wherein a direction along a fiber direction of the wood is set to a compression direction, and the wood is formed by being subjected to compressive force.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of PCT/JP2005/001158 filed on Jan. 21, 2005, which claims priority to Japanese Patent Application No. 2004-013240, filed on Jan. 21, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1) Field of the Invention  
         [0003]     The present invention relates to a compressed wood product including a compressed wood and an electronic device exterior material including the compressed wood product.  
         [0004]     2) Description of the Related Art  
         [0005]     Examples of a portable electric device that can be operated on hand include a camera, a mobile communication device (mainly cellular phone), an IC recorder, a PDA, a portable television, a portable radio, and remote controls for various home appliances. Usually, synthetic resins (ABS, polycarbonate, acrylic, and the like) and light metals (aluminum, stainless steel, titanium, magnesium, and the like) are used as the portable electronic device exterior material due to industrial mass production. Such the synthetic resins and light metals constituting the exterior material are oriented to industrial products while appropriate strength is obtained, so that there is no individual difference in appearance. Further, in the synthetic resins and the light metals constituting the exterior material, a flaw and discoloration are generated in long-term use. However, the flaw and the discoloration only impair the worth of the electronic device.  
         [0006]     Therefore, it is thought that one may use wood which is of a natural raw material as the exterior material. Because the wood has various kinds of grain, the wood has the individual difference and individuality. Although the flaw and a change in color shade are generated in the long-term use in the wood, they become the unique feel and texture of the wood to cause users to feel an affinity.  
         [0007]     A conventional method is well known in which the wood softened by absorbing moisture is compressed and held to fix a shape, then is sliced in a compression direction to obtain a plate-shaped primary fixed product, the primary fixed product is formed in a formed product having a predetermined three-dimensional shape while heated and absorbed, and the shape of the formed product is fixed to obtain a secondary fixed product (for example, see Japanese Patent No. 3078452).  
         [0008]     A conventional method is well known, in which a woody material compressed in a state in which the softening treatment is performed is temporarily fixed and then is recovered in a form to perform forming, as a method of three-dimensionally processing the woody material (for example, see Japanese Patent Application Laid-Open No. 11-77619).  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to at least solve the problems in the conventional technology.  
         [0010]     A compressed wood product according to one aspect of the present invention includes a wood whose shape is taken while a volume decreased by compression is previously added, wherein a direction along a fiber direction of the wood is set to a compression direction, and the wood is formed by being subjected to compressive force. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a sectional view that depicts an electronic device in which a compressed wood product according to a first embodiment is used as an exterior material;  
         [0012]      FIG. 2  is a perspective view that depicts shape taking of a compressed wood product according to the first embodiment;  
         [0013]      FIG. 3  is a plan view that depicts shape taking of a compressed wood product according to the first embodiment;  
         [0014]      FIGS. 4A  to  4 C are views that depict a process of compressing wood;  
         [0015]      FIGS. 5A and 5B  are sectional views that depict wood with a reinforcement structure; and  
         [0016]      FIG. 6  is a perspective view that depicts wood with another reinforcement structure. 
     
    
     DETAILED DESCRIPTION  
       [0017]     Exemplary embodiments of a compressed wood product relating to the present invention will be explained in detail below with reference to the accompanying drawings.  
         [0018]      FIG. 1  is a sectional view that depicts an electronic device in which a compressed wood product according to the first embodiment is used as an exterior material. In  FIG. 1 , a digital camera is shown as an example of the electronic device. The digital camera has a reinforcing frame  11  and an inner mechanism  12  inside an exterior material  10  formed by the compressed wood product. The digital camera also has an image taking lens  13  and a liquid crystal monitor  14  while the image taking lens  13  and the liquid crystal monitor  14  are exposed to the outside of the exterior material  10 . The inner mechanism  12  includes an image pickup device  12   a  such as a CCD, a drive circuit  12   b  that drives the image pickup device  12   a , a drive circuit  12   c  that drives the liquid crystal monitor  14 , a recording device  12   d  for an image recording medium C, and a connection terminal  12   e  connected to an external personal computer.  
         [0019]     The exterior material  10  includes a front cover  10   a  and a rear cover  10   b . A lens hole  10   c  is made in a main plate portion of the front cover  10   a  so that the image taking lens  13  is projected outside of the front cover  10   a . The lens hole  10   c  is made corresponding to an outer shape of a holding portion that holds the image taking lens  13 . For example, when the holding portion has a cylindrical shape, the lens hole  10   c  is made in a circular shape so that the holding portion is projected outside of the front cover  10   a . An aperture  10   d  is provided in a side plate portion of the front cover  10   a  so that the image-recording medium C is inserted into or extracted from the aperture  10   d . A rectangular window  10   e  is made in the main plate portion of the rear cover  10   b  so that the liquid crystal monitor  14  is exposed outside of the rear cover  10   b . An aperture  10   f  is provided in the side plate portion of the rear cover  10   b  so that a connection cable connected to the connection terminal  12   e  is inserted into or extracted from the aperture  10   f . In addition, although not shown in the drawings, button holes are made in the front cover  10   a  and the rear cover  10   b  so that various operation buttons for operating the digital camera are exposed. A cover and the like may be provided in the button hole if needed.  
         [0020]      FIG. 2  is a perspective view that depicts shape taking of the compressed wood product according to the first embodiment, and  FIG. 3  is a plan view that depicts shape taking of the compressed wood product according to the first embodiment. As shown in  FIG. 2 , the compressed wood product constituting the exterior material  10  is made by compressing a wood  1 . The shape of the wood  1  is taken from a raw material  100  before the wood  1  is compressed. Examples of the raw material  100  include Japanese cypress (hinoki, hiba), paulownia (kiri), teak, mahogany, Japanese cedar, pine, and cherry. The wood  1  is a lump including a main plate portion  1   a  having a predetermined shape (substantially rectangular shape in the first embodiment) and a side plate portion  1   b  provided while vertically rising from a periphery of the main plate portion  1   a . The main plate portion  1   a  forms the main plate portion of the front cover  10   a  or the rear cover  10   b , and the side plate portion  1   b  forms the side plate portion of the front cover  10   a  or the rear cover  10   b . In the wood  1 , the main plate portion  1   a  and the side plate portion  1   b  are formed so as to be coupled to each other in a smooth curved surface.  
         [0021]     As shown in  FIG. 3 , with reference to a mode in which the shape of the wood  1  is taken from the raw material  100 , the shape of the wood  1  is taken while a thickness direction of the main plate portion  1   a  exists along the fiber direction and the surface that reveals itself in the thickness direction has the end grain surface.  
         [0022]      FIG. 4  is a view that depicts a process of compressing the wood. The shape of the wood  1  is taken while a volume decreased by the compression is previously added. Specifically, as shown in  FIG. 4A , the shape of the main plate portion  1   a  is taken with a thickness W 1  in which the volume decreased by the compression is previously added. The shape of the side plate portion  1   b  is taken with a thickness W 2  and a height T 1  in which the volume decreased by the compression is previously added. The shape of the wood  1  is taken with a total width H 1 . The thickness W 1  of the main plate portion  1   a  is formed larger than the thickness W 2  of the side plate portion  1   b . A middle portion between the main plate portion  1   a  and the side plate portion  1   b  is formed in the smooth curve so that the thickness W 1  of the main plate portion  1   a  is gradually changed to the thickness W 2  of the side plate portion  1   b . The side plate portion  1   b  is formed so as to rise obliquely outward from the main plate portion  1   a . In the wood  1 ,  FIG. 4  shows the shape of either the front cover  10   a  or the rear cover  10   b  in the exterior material  10  formed of the compressed wood product. The drawing and the description of the shape of the other are not repeated, because the shapes of the front cover  10   a  and the rear cover  10   b  are similar to each other.  
         [0023]     The wood  1  is compressed between a lower form frame A and an upper form frame B. As shown in  FIG. 4A , the lower form frame A has a concave surface that hits against a curved outside surface (lower surface in  FIG. 4 ). In the curved outside surface, the side plate portion  1   b  rises from the main plate portion  1   a  of the wood  1 . The concave surface of the lower form frame A has the shape to which the outside surface of the wood  1  is fitted. The radius of curvature of a curved surface RO at the outside surface of the wood  1  and the radius of curvature of a curved surface RA at the lower form frame A that is opposite to the curved surface RO have a correlation of RO&gt;RA. On the other hand, the upper form frame B has a convex surface that hits against a curved inside surface (upper surface in  FIG. 4 ). In the curved inside surface, the side plate portion  1   b  rises from the main plate portion  1   a  of the wood  1 . The convex surface of the upper form frame B has the shape to which the inside surface of the wood  1  is fitted. The radius of curvature of a curved surface RI at the inside surface of the wood  1  and the radius of curvature of a curved surface RB at the upper form frame B that is opposite to the curved surface RI have the correlation of RI&gt;RB. After the lower form frame A and the upper form frame B are combined, i.e. after the wood  1  is compressed, a space formed between the concave surface of the lower form frame A and the convex surface of the upper form frame B has the shape of post-compression of the wood  1 . (see  FIG. 4B ).  
         [0024]     With reference to the wood  1  and the lower and upper form frames A and B having the above-described configurations, first the wood  1  is placed in a water vapor atmosphere at high temperature and high pressure as shown in  FIG. 4A . When the wood  1  is placed in the water vapor atmosphere at high temperature and high pressure for a predetermined time, the wood  1  is softened by excessively absorbing moisture. In the water vapor atmosphere at high temperature and high pressure, the wood  1  is arranged between the lower form frame A and the upper form frame B and on the concave surface of the lower form frame A. At this point, since the main plate portion  1   a  has the end grain surface, the wood  1  has the mode in which a direction M in which the pieces of grain G are laminated exists in a horizontal direction of  FIG. 4  and a fiber direction L exists along a vertical direction of  FIG. 4 .  
         [0025]     Then, as shown in  FIG. 4B , the wood  1  is compressed by bringing the upper form frame B close to the lower form frame A. Namely, the convex surface of the upper form frame B is fitted into the concave surface of the lower form frame A. In the wood  1  sandwiched between the lower form frame A and the upper form frame B, compressive force is applied to the main plate portion  1   a  in the thickness W 1  direction (direction along the grain G), and the compressive force is also applied to the main plate portion  1   a  in the direction along the fiber direction L. In the wood  1 , the compressive force is applied to the side plate portion  1   b  in the thickness W 2  direction (direction M in which the pieces of grain G are laminated) and in the height T 1  direction (direction along the grain G), and the compressive force is also applied to the side plate portion  1   b  in the direction along the fiber direction L. Further, in the wood  1 , the compressive force is applied to a curved portion  1   c  that couples the main plate portion  1   a  and the side plate portion  1   b  in the direction M in which the pieces of grain G are laminated and in the direction along the grain G, and the compressive force is also applied to the curved portion  1   c  in the direction along the fiber direction L. Specifically, the curved portion  1   c  is formed so that the side plate portion  1   b  rises obliquely outward, and the radii of curvature of the lower and upper form frames A and B has the relationship described above. Therefore, the compressive force is applied upward to the outside surface of the curved portion  1   c , and the compressive force is applied downward to the inside surface. Then, the wood  1  is left for a predetermined time while the compressive force is applied to the wood  1 .  
         [0026]     Finally, after the wood  1  is left for the predetermined time, the water vapor atmosphere at high temperature and high pressure is released, the upper form frame B is separated from the lower form frame A, and the compressed wood  1  is taken out as shown in  FIG. 4C . In the compressed wood  1  taken out from between the lower and upper form frames A and B, the wood  1  is compressed to substantially even thicknesses W 1 ′and W 2 ′ at the main plate portion  1   a  and the side plate portion  1   b , respectively. In the compressed wood  1 , the side plate portion  1   b  is compressed to a height T 1 ′. In the compressed wood  1 , the curved portion  1   c  that couples the main plate portion  1   a  and the side plate portion  1   b  is compressed so that the pieces of grain G are laminated. The compressed wood  1  is slightly compressed to a width H 1 ′.  
         [0027]     Thus, in the compressed wood  1 , since the compressive force is applied in the direction along the fiber direction L, the cut surface of the fiber reveals itself in the compressed surface. As a result, the perspiration-absorption characteristics can be improved. Particularly, since the main plate portion  1   a  has the end grain surface, the cut surface of the fiber reveals itself. Therefore, the higher perspiration-absorption characteristics are obtained to improve portability. Further, since the main plate portion  1   a  has the end grain surface, the shapes of the wood  1  having the similar end grain surface can be taken. Therefore, the compressed woods with the equivalent strength and pattern can be obtained.  
         [0028]     In the side plate portion  1   b , since the compressive force is applied in the direction M in which the pieces of grain G are laminated, the pieces of hard fiber of the grain G are bundled to increase fiber density, which imparts the high strength to the side plate portion  1   b . Further, in the curved portion  1   c  that couples the main plate portion  1   a  and the side plate portion  1   b , since the compressive force is applied in the direction M in which the pieces of grain G are laminated, the fiber density is increased to impart the high strength to the curved portion  1   c.    
         [0029]     Thus, the compressed wood product has the sufficient perspiration-absorption characteristics for the electronic device exterior material by using the compressed wood product as the electronic device exterior material.  
         [0030]     As described above, when the surface in the thickness direction of the main plate portion  1   a  has the end grain surface, it is expected that the strength is decreased against pressing force toward the direction of the surface. Therefore, it is preferable to reinforce the surface in the thickness direction of the main plate portion  1   a  as follows.  
         [0031]      FIG. 5  is a sectional view that depicts the wood with a reinforcement structure. In the reinforcement structure shown in  FIG. 5 , a plurality of rod-shaped materials  2  are arranged in parallel as the reinforcement material with respect to the inside surface of the main plate portion  1   a . The rod-shaped material  2  is formed of a metal material or a synthetic resin that is harder than the wood  1 . In this case, as shown in  FIG. 5A , the rod-shaped materials  2  are arranged in parallel on the inside surface of the wood  1  at predetermined intervals before the compression. Then, as shown in  FIG. 5B , the rod-shaped materials  2  are embedded into the inside surface of the wood  1  to be integrated with the wood  1  by the compression. This allows the strength of the main plate portion  1   a  to be improved in the wood  1 . The strength of the main plate portion  1   a  is further improved in the wood  1  by providing the rod-shaped material  2  while orientated toward the direction intersecting the grain G. When the rod-shaped material  2  made of metal is quenched, the strength of the main plate portion  1   a  can be improved by metal hardening.  
         [0032]      FIG. 6  is a perspective view that depicts the wood with another reinforcement structure. In the reinforcement structure shown in  FIG. 6 , a network material  3  is arranged as the reinforcement material with respect to the inside surface of the main plate portion  1   a . The network material  3  is formed of a metal material or a synthetic resin that is harder than the wood  1 . In this case, similarly to the mode shown in  FIG. 5 , the network material  3  is embedded into the inside surface of the wood  1  to be integrated with the wood  1  by the compression. Because the network material  3  is formed by intersecting a plurality of linear materials  3   a  one another, the wood with the reinforcement structure shown in  FIG. 6  has the high strength in the surface direction. In addition to the network material  3 , when a punching metal and the like are used as the reinforcement material, the strength of the main plate portion  1   a  can also be improved.  
         [0033]     It is possible to burn the surface of the wood  1  (compressed wood product) obtained by the compression in the embodiment. Depressions and projections are generated in the grain G portion by burning the surface of the wood  1 , which further improves the perspiration-absorption characteristics and the effect of the slip resistance. Further, a carbonized layer obtained by burning the surface of the wood  1  becomes a conductive material, and the carbonized layer becomes an electromagnetic shielding material which is far lighter than metal, so that the wood  1  obtained by the compression can be used effectively as the electronic device exterior material.  
         [0034]     In the embodiment, the compressed wood product having the structure in which the side plate portion  1   b  rises from the main plate portion  1   a  is described as an example. However, the invention is not limited to the embodiment. As described above, the invention can be applied to any shape of goods, e.g. tableware, as long as the perspiration-absorption characteristics are obtained by applying the compressive force in the direction along the fiber direction L of the wood  1 . For the electronic device exterior material, the invention is not limited to the digital camera, but the invention can be applied to the portable electronic device such as a camera, a mobile communication device (mainly cellular phone), an IC recorder, a PDA, a portable television, a portable radio, and remote controls for various home appliances.  
         [0035]     It is known that the wood has the nature to generate perspiration-absorption characteristics, so as to conform to a human hand when a user touches the wood. In order to obtain the perspiration-absorption characteristics it is necessary that a cut surface of wood fiber reveals itself as the surface which the user should touch. In the above conventional art, because the wood compressed is first cut along a fiber direction, the surface that reveals itself becomes a flat-grain surface, a straight-grain surface, or an edge-grain surface, which reduces the perspiration-absorption characteristics. However, in the embodiments explained above, the compressed wood product and the electronic device exterior material are suitable for the improvement of the perspiration-absorption characteristics by previously considering the compression direction with respect to the wood to take the shape of the wood and performing the compression forming.  
         [0036]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.