Housing and electronic device

Provided are a housing and an electronic device that ensure sufficient strength even when reduced in thickness. A carbon fiber layer included in the housing is disposed such that the orientation direction of carbon fibers is perpendicular to the lengthwise direction of the long sides of a back face panel, thus enabling improving the flexural strength of the back face panel. This enables increases in the number of carbon fibers per unit of area of the back face panel, and enables the length of each carbon fiber to be reduced. Accordingly, it is possible to cause the carbon fibers to flex less readily, thus enabling improving the strength in the flexing direction of the back face panel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a housing and an electronic device.

2. Description of Related Art

In recent years, various innovations have been made in order to improve the strength of housings for mobile electronic devices such as notebook personal computers (hereinafter, referred to as “notebook PCs”). One example of a configuration for improving the strength of a housing is disclosed in Patent Literature 1 (JP 2005-150668A).

A material containing a carbon fiber reinforced plastic as a main component is used for the electronic device housing disclosed in Patent Literature 1. This material is made up of multiple layers, and the carbon fibers included in the outermost layer are continuous long fibers that are oriented in one direction. Also, the carbon fibers included in the outermost layer are oriented in a direction that is oblique to the outer edge of the material.

However, with the configuration disclosed in Patent Literature 1, in which the carbon fibers are oriented in a direction oblique to the outer edge of the material, both ends of the carbon fibers disposed near the center of the housing are disposed on the diagonal lines of the housing or in the vicinity of the diagonal lines, and the overall length of the carbon fiber material increases. Since carbon fibers flex more readily as their overall length increases, it is difficult to ensure sufficient strength for the housing. In other words, with the configuration disclosed in Patent Literature 1, it is difficult to ensure sufficient flexural strength for the carbon fiber material disposed near the center of the housing.

SUMMARY OF THE INVENTION

A housing according to the present invention is a housing including a carbon fiber layer that contains a carbon fiber reinforced plastic, the carbon fiber layer being configured having a planar shape that has at least a pair of long sides, and containing carbon fibers that have one orientation direction. The carbon fiber layer is disposed such that the orientation direction of the carbon fibers is perpendicular to a lengthwise direction of the long sides.

An electronic device according to the present invention includes the above-described housing.

According to the present invention, it is possible to provide a housing and an electronic device that enable sufficient strength to be ensured even when reduced in thickness.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be described by way of illustrative embodiments with reference to the drawings.

1. Electronic Device Configuration

FIGS. 1A and 1Bare perspective views of the exterior of a notebook PC according to the present embodiment. Note that although a notebook PC is taken as an example of an electronic device in the present embodiment, the electronic device may be another electronic device as long as it is provided with a housing that includes at least carbon fibers. In particular, an electronic device for which high resistance to drop impact and the like is required, such as a mobile electronic device, is preferable.

As shown inFIG. 1A, the notebook PC includes a first housing1and a second housing2. Circuit boards on which various types of electrical elements are provided, a hard disk drive, and the like are housed in the first housing1. The second housing2includes a display panel4. The display panel4can be embodied by a liquid crystal display (LCD) panel, for example. The first housing1and the second housing2are supported by a hinge portion3so as to be capable of opening and closing with respect to each other by pivoting.FIG. 1Ashows the state in which the second housing2has been opened up from the first housing1.FIG. 1Bshows the state in which the second housing2has been closed down onto the first housing1. The hinge portion3includes a shaft (not shown) that supports the first housing1and the second housing2so as to be capable of opening and closing.

A keyboard5and a pointing device6are disposed on an upper face1aof the first housing1. The keyboard5accepts operations performed by a user for inputting various types of characters. The pointing device6is a device for accepting contact operations performed by the user on the operation face thereof, and enables an operation for moving a cursor displayed on the display panel4to a desired position.

As shown inFIG. 1B, the second housing2includes carbon fibers23hthat are oriented in a predetermined direction. Note that the specific configuration of the second housing2will be described below.

2. Second Housing Configuration

FIG. 2is an exploded perspective view of the second housing2. As shown inFIG. 2, the second housing2mainly includes a front face panel21, a display panel22, and a back face panel23.

The front face panel21is formed such that the planar shape thereof is substantially rectangular. The front face panel21includes a frame portion21aand an opening portion21b. The frame portion21adefines the size and shape of the opening portion21b. The opening portion21bmakes it possible for images displayed in an effective display area of the display panel22to be viewed from the outside.

The display panel22is formed such that the planar shape thereof is rectangular. The display panel22corresponds to the display panel4shown inFIG. 1A. In the present embodiment, a liquid crystal display panel is employed as the display panel22. The display panel22is sandwiched between the front face panel21and the back face panel23. The display panel22can display display images on a front face22aside thereof. The display panel22is disposed such that the front face22aopposes the front face panel21, and a back face22bopposes the back face panel23.

The back face panel23is formed such that the planar shape thereof is rectangular. The back face panel includes a flat plate portion23a, a first wall portion23b, a second wall portion23c, a third wall portion23d, and a fourth wall portion23e.The flat plate portion23ais formed such that the planar shape thereof is rectangular. The flat plate portion23ais formed such that the size of a principal face23gthereof is greater than that of at least the back face22bof the display panel22. The flat plate portion23acan cover the back face22bof the display panel22. The first wall portion23b, the second wall portion23c, the third wall portion23d, and the fourth wall portion23eare provided upright on the four sides surrounding the flat plate portion23a, and the mutually adjacent wall portions are joined together. The first wall portion23band the second wall portion23care in contact with the long sides of the flat plate portion23a. In other words, the “long sides of the back face panel23” refers to the outer sides of the flat plate portion23awith which the first wall portion23band the second wall portion23care in contact. The third wall portion23dand the fourth wall portion23eare in contact with the short sides of the flat plate portion23a. The first wall portion23b, the second wall portion23c, the third wall portion23d, and the fourth wall portion23eare joined to the front face panel21when the second housing2is in the completely assembled state. An outer face23fis the face on the reverse side of the principal face23g, and is the face that is exposed to the outside when the second housing2is in the completely assembled state.

FIG. 3is a plan view of the back face panel23of Embodiment1.FIG. 4is a cross-sectional view taken long line Z-Z inFIG. 3. As shown inFIGS. 3 and 4, the back face panel23is configured by a carbon fiber layer23k.

The carbon fiber layer23kis configured by a material containing a CFRP (Carbon Fiber Reinforced Plastic) as a main component. Specifically, the carbon fiber layer23kis a composite material formed by incorporating multiple uniaxially-oriented carbon fibers23hin a thermosetting resin (e.g., epoxy resin) and then performing thermal curing while stretching the material into a sheet, and this composite material is commercially available in various thicknesses. In the present embodiment, the carbon fiber layer23kis configured by a material containing 35% epoxy resin and 65% carbon fibers, with a layer thickness of 0.12 mm to 0.17 mm and a carbon fiber filament count of 3000, but these numerical values are merely exemplary. The carbon fiber layer23kis made up of a commercially-available single-layer material with a thickness of 0.12 mm, for example. The carbon fibers23hare oriented in one direction, and are long fibers that are continuous in that direction. The carbon fiber layer23kis configured such that the orientation direction of the carbon fibers23his perpendicular to the lengthwise direction of the long sides of the back face panel23as shown inFIG. 3(i.e., parallel to the lengthwise direction of the short sides of the back face panel23). Specifically, the carbon fibers23hare arranged on the flat plate portion23aso as to extend from the first wall portion23bof the back face panel23or the vicinity thereof to the second wall portion23cor the vicinity thereof. Note that the carbon fibers23hshown inFIG. 3are illustrated schematically.

In the present embodiment, the back face panel23is configured by the carbon fiber layer23k, and furthermore the orientation direction of the carbon fibers23hcontained in the carbon fiber layer23kis set perpendicular to the lengthwise direction of the long sides of the back face panel23, and this enables the flexural strength of the back face panel23to be improved since a greater number of carbon fibers23hcan be provided. Note that “flexure” refers to deformation that the back face panel23undergoes due to force applied in a direction orthogonal to the outer face23fof the back face panel23.

Also, setting the orientation direction of the carbon fibers23hso as to be perpendicular to the lengthwise direction of the long sides of the back face panel23enables the length of the carbon fibers23hto be reduced, thus causing the carbon fibers23hto flex less readily and improving the flexural strength of the back face panel23.

Also, configuring the back face panel23from only the carbon fiber layer23kenables the weight of the back face panel23to be reduced. Furthermore, configuring the back face panel23from only the carbon fiber layer23kenables the cost of the back face panel23to be reduced. Moreover, configuring the back face panel23from only the carbon fiber layer23kenables the easy insertion of a decoration such as a logo between the carbon fibers and the thermosetting resin on the outer face surface of the back face panel23on the23f.

Also, providing the back face panel23with the first wall portion23b, the second wall portion23c, the third wall portion23d, and the fourth wall portion23eimproves the strength in the planar direction of the principal face23gand improves the robustness of the second housing2.

Note that it is preferable that a conductive member made of a metal foil, a metal film, or the like is provided on the principal face23gand, among the first wall portion23b, the second wall portion23c, the third wall portion23d, and the fourth wall portion23eof the back face panel23, the face of at least any one thereof that is on the principal face23gside. This configuration helps suppress unnecessary radiation generated by drive signals applied to the display panel22and the circuits with signal-generating parts mounted thereon that are included in the second housing2. Also, this configuration enables electrical connection of the conductive member and the electrical circuits included in the second housing2, and enables grounding of the electrical circuits.

Also, it is preferable that a conductive member made of a metal or the like is provided on the outer face23fof the back face panel23. This configuration enables suppression of unnecessary radiation generated by drive signals applied to the display panel22and the circuits with signal-generating parts mounted thereon that are included in the second housing2.

Also, in the case of applying CFRP to the housing, it is conceivable to increase the amount of carbon fibers23hcontained in the thermosetting resin in order to improve the mechanical strength. As a result of increasing the amount of carbon fibers23hcontained in the thermosetting resin, there is an increased tendency for the front face23fof the CFRP to become rough, and scratching and the like more readily occur. In the case of this configuration, scratch prevention processing can be performed on the outer face23fof the carbon fiber layer23k. Note that although it is effective to provide the above-described conductive member as a configuration for protecting the outer face23fof the carbon fiber layer23kfrom scratching and the like, there is no limitation to this configuration, and a configuration is possible in which, for example, a protective member made of a nonconductor such as resin is provided.

Also, although the back face panel23is formed such that the planar shape thereof is rectangular in the present embodiment, there is no limitation to being rectangular, and effects of the carbon fiber layer23kof the present embodiment can be obtained as long as the shape of the back face panel has at least one pair of long sides.

Also, although the carbon fiber layer23kis provided on the second housing2in the present embodiment, providing the carbon fiber layer23kon the first housing1enables improvement in the flexural strength of the first housing1. Furthermore, providing the carbon fiber layer23kon both the first housing1and the second housing2enables improvement in the overall flexural strength of the notebook PC. Moreover, this configuration enables magnetically shielding of a magnetic recording medium such as the hard disk drive included in the first housing1.

Also, although the carbon fiber layer23kis provided on the back face panel23in the present embodiment, the carbon fiber layer23kcan be provided on the front face panel21as well.

Also, although the carbon fiber layer23kis disposed such that the orientation direction of the carbon fibers23his perpendicular to the lengthwise direction of the long sides of the back face panel23in the present embodiment, there is no limitation to a configuration in which “perpendicular” refers to the orientation direction of the carbon fibers23hand the lengthwise direction of the long sides of the back face panel23forming an exactly 90-degree angle, and some margin of error in the angle is possible. In other words, when cutting a carbon fiber sheet of an arbitrary size from a carbon fiber sheet (original roll) in order to prepare the carbon fiber layer23kfor example, there are cases where there is a slight error in the cut size. In this case, it is possible for the orientation direction of the carbon fibers23hand the lengthwise direction of the long sides of the back face panel23to not form a 90-degree angle. In the present embodiment, “perpendicular” includes this margin of error in the angle.

Also, the first housing1, the second housing2, and the back face panel23are examples of a housing. The notebook PC is one example of an electronic device. The carbon fiber layer23kis one example of a carbon fiber layer. The carbon fibers23hare one example of carbon fibers. The outer side of the flat plate portion23athat is in contact with the first wall portion23b, and the outer side of the flat plate portion23athat is in contact with the second wall portion23care examples of the long sides of the back face panel23.

FIG. 5is a plan view of a back face panel13(outer face13fside thereof) of Embodiment 2.FIG. 6is a cross-sectional view taken long line Z-Z inFIG. 5. As shown inFIG. 6, the back face panel13has a three-layer structure including a carbon fiber layer13kas well as a first layer13mand a second layer13nthat are disposed so as to sandwich the carbon fiber layer13k.

Note that the back face panel13can be applied to the second housing2shown inFIGS. 1 and 2. Specifically, the back face panel13can be applied instead of the back face panel23shown inFIG. 2. Also, aspects of the configuration other than the back face panel13are similar to those in Embodiment 1, and therefore detailed descriptions thereof will not be given.

The carbon fiber layer13kis configured by a material containing a CFRP (Carbon Fiber Reinforced Plastic) as a main component. Specifically, the carbon fiber layer13kis a composite material formed by incorporating multiple uniaxially-oriented carbon fibers13hin a thermosetting resin (e.g., epoxy resin) and then performing thermal curing while stretching the material into a sheet, and this composite material is commercially available in various thicknesses. In the present embodiment, the carbon fiber layer13kis configured by a material containing 35% epoxy resin and 65% carbon fibers, with a layer thickness of 0.12 mm to 0.17 mm and a carbon fiber filament count of 3000, but these numerical values are merely exemplary. The carbon fiber layer13kis made up of a commercially-available single-layer material with a thickness of0.12mm, for example. The carbon fibers13hare oriented in one direction, and are long fibers that are continuous in that direction. The carbon fiber layer13kis configured such that the orientation direction of the carbon fibers13his perpendicular to the lengthwise direction of the long sides of the back face panel13as shown inFIG. 5(i.e., parallel to the lengthwise direction of the short sides of the back face panel13). Specifically, the carbon fibers13hare arranged on a flat plate portion13aso as to extend from a first wall portion13bof the back face panel13or the vicinity thereof to a second wall portion13cor the vicinity thereof. Note that the carbon fibers13hshown inFIG. 5are illustrated schematically.

The first layer13mis stacked on and joined to a first principal face of the carbon fiber layer13k. Although the first layer13mcan be formed from a resin or a metal, it is preferable that the first layer13mis formed from a high-hardness material due to its being a portion that constitutes the outline of the notebook PC. In the present embodiment, the first layer13mis formed from magnesium.

The second layer13nis stacked on and joined to a second principal face of the carbon fiber layer13kthat is on the reverse side of the first principal face. It is preferable that the second layer13nis formed from a resin or a metal, and in the present embodiment, the second layer13nis formed from magnesium, for example.

As shown inFIGS. 5 and 6, the carbon fiber layer13kis provided on the back face panel13, and furthermore the orientation direction of the carbon fibers13hcontained in the carbon fiber layer13kis set perpendicular to the lengthwise direction of the long sides of the back face panel13, and this enables improvement in the flexural strength of the back face panel13since a greater number of carbon fibers13hcan be provided. Note that “flexure” refers to deformation that the back face panel13undergoes due to force applied in a direction orthogonal to the outer face13fof the back face panel13.

Also, setting the orientation direction of the carbon fibers13hso as to be perpendicular to the lengthwise direction of the long sides of the back face panel13enables the length of the carbon fibers13hto be reduced, thus causing the carbon fibers13hto flex less readily and improving the flexural strength of the back face panel13.

The following describes the relationship between the orientation direction of the carbon fibers and the flexural strength of the back face panel that includes the carbon fiber layer.

FIG. 7Ais an illustrative diagram showing an overview of a method for testing the strength of the back face panel.FIG. 7Bis a graph showing the results of the test.FIG. 8is a plan view of the back face panel of Comparative Example 1.FIG. 9is a plan view of the back face panel of Comparative Example 2.

The back face panels used in the strength test were the back face panel13(Example 1) shown inFIG. 5, a back face panel100(Comparative Example 1) shown inFIG. 8, and a back face panel200(Comparative Example 2) shown inFIG. 9.

The back face panel13of Example 1 was provided with a carbon fiber layer disposed such that the orientation direction of the carbon fibers was perpendicular to the lengthwise direction of the long sides of the back face panel13. The back face panel100of Comparative Example 1 was provided with a carbon fiber layer disposed such that the orientation direction of carbon fibers101was parallel to the lengthwise direction of the long sides of the back face panel100. The back face panel200of Comparative Example 2 was provided with a carbon fiber layer disposed such that the orientation direction of carbon fibers201was oblique to the lengthwise direction of the long sides of the back face panel200. The back face panels13,100, and200were configured including a carbon fiber layer with a thickness of 0.12 mm, a first aluminum layer with a thickness of 0.2 mm, and a second aluminum layer with a thickness of 0.2 mm, with the carbon fiber layer being sandwiched between the first aluminum layer and the second aluminum layer to form a laminate. Also, the back face panels13,100, and200were formed such that the planar shape thereof was rectangular, and had a flat plate shape with a depth dimension D1of 182 mm, a width dimension W1of 277 mm, and a thickness dimension H1of 0.52 mm. Also, specifications such as the carbon fiber filament count, density, and tensile strength were all the same for the carbon fiber layers included in the back face panels13,100, and200. In other words, the carbon fiber layers included in the back face panels13,100, and200were prepared by using different cutting methods when the carbon fiber sheets to be used as the carbon fiber layers were cut out of one type of carbon fiber sheet (original roll).

The flexural strength of the back face panels13,100, and200configured as described above was measured using a predetermined measuring apparatus. Specifically, as shown inFIG. 7A, the four surrounding sides of the back face panels were fixed, a constant weight was applied focused in the direction indicate by arrow D in the center of the outer face (e.g., the outer face13fshown inFIG. 2), and the amount of deformation in the vicinity of the center of the back face panel was measured. The amount of deformation was obtained by measuring the distance between the position of the outer face of the back face panel when no weight was applied and the position of the outer face of the back face panel when the constant weight was applied. As a result, as shown inFIG. 7B, the amount of deformation when the constant weight was applied to the back face panels was the least for the back face panel13of Example 1 among the three types of back face panels. Also, the amount of deformation of the back face panel200of Comparative Example 2 was higher than the amount of deformation of the back face panel13of Example 1. Moreover, the amount of deformation of the back face panel100of Comparative Example 1 was higher than the amount of deformation of the back face panel200of Comparative Example 2. In other words, it was found that the back face panel13of Example1had the highest flexural strength among the three types of back face panels.

3. Effects of the Embodiment and Other Remarks

According to the present embodiment, providing the carbon fiber layer13kdisposed such that the orientation direction of the carbon fibers13his perpendicular to the lengthwise direction of the long sides of the back face panel13enables improving the flexural strength of the back face panel13. Specifically, due to orienting the carbon fibers13hso as to be perpendicular to the lengthwise direction of the long sides of the back face panel13, the number of carbon fibers13provided on the back face panel13can be greater than that in Comparative Example 1 (e.g., seeFIG. 8) in which the carbon fibers are oriented so as to be parallel with the lengthwise direction of the long sides of the back face panel, thus enabling improved flexural strength of the back face panel13. Also, due to orienting the carbon fibers13hso as to be perpendicular to the lengthwise direction of the long sides of the back face panel13, the length of the carbon fibers13hcan be reduced, thus enabling causing the carbon fibers13hto flex less readily and improving the flexural strength of the back face panel13.

Also, according to the present embodiment, the carbon fiber layer13kis a thin layer with a thickness of approximately 0.12 mm to 0.17 mm, and therefore even if the back face panel13is provided with the carbon fiber layer13k, the increase in the overall thickness of the back face panel13is not significant, thus enabling improved flexural strength while maintaining the thickness of the second housing2.

Also, according to the present embodiment, the strength of the back face panel13can be ensured even if the long sides of the second housing2and the back face panel13are lengthened in order for the aspect ratio of the effective display area of the display panel4to be made wider (e.g., to an aspect ratio of 16:9) than the aspect ratio that has often be employed in the display panels of conventional notebook PCs. Specifically, in the case where the long sides of the second housing2and the back face panel13are lengthened without the short sides being changed from those of conventional technology, with the Comparative Example 1 (e.g., seeFIG. 8) in which the carbon fibers are oriented so as to be parallel with the lengthwise direction of the long sides of the back face panel, the carbon fibers simply increase in length and do not increase in number. When the carbon fibers increase in length, the carbon fibers each flex more readily, and the flexural strength of the back face panel decreases. In contrast, with the present embodiment, in the case where the long sides of the second housing2and the back face panel13are lengthened, the length of each carbon fiber13hdoes not change, but the number of carbon fibers13hincreases. In other words, with the back face panel13of the present embodiment, the flexural strength of each carbon fiber13hcan be maintained since the length of each carbon fiber13hdoes not change, and the number of carbon fibers13hincreases, thus improving the flexural strength. Accordingly, with the present embodiment, the flexural strength of the back face panel13can be ensured even if the long sides of the second housing2and the back face panel13are lengthened.

Also, in the present embodiment, providing the second housing2with the carbon fiber layer13kenables reducing curvature deformation of the second housing2when the second housing2is pivoted in the direction indicated by arrow A or arrow B with the respect to the first housing1. Specifically, when the user opens and closes the second housing2in the direction indicated by the arrow A and the arrow B, the user often grips a first long side portion2aof the second housing2. Since a second long side portion2bof the pair of long sides of the second housing2is joined to the first housing1via the hinge portion3, there are cases where the second housing2undergoes curvature deformation in which the short sides flex when the user grips the first long side portion2aand opens or closes the second housing2. In particular, in the case where the torque (open/close load) of the hinge mechanism included in the hinge portion3is high, there is an increased possibility of the short sides of the second housing2undergoing curvature deformation. In this case, if the flexural strength of the back face panel13is low, the second housing2undergoes a large amount of curvature deformation, and there is the possibility of damage such as cracking of the display panel22. In the present embodiment, the back face panel13is provided with the carbon fiber layer13k, and furthermore the orientation direction of the carbon fibers13hincluded in the carbon fiber layer13kis set parallel with the lengthwise direction of the short sides of the back face panel13, thus enabling improving the flexural strength in the lengthwise direction of the short sides of the second housing2and suppressing curvature deformation. Accordingly, the present embodiment enables suppressing of curvature deformation when the user grips the long side portion2aand opens or closes the second housing2, and preventing damage to the display panel22, for example.

Also, according to the present embodiment, providing the carbon fiber layer13kdisposed such that the orientation direction of the carbon fibers13his perpendicular to the lengthwise direction of the long sides of the back face panel13enables improved yield when manufacturing the back face panel13. Specifically, a carbon fiber sheet of an arbitrary size that has been cut out from a large-size carbon fiber sheet (original roll) generally wound into a roll is used as the carbon fiber layer13k. With a carbon fiber sheet wound into a roll, it is often the case that the carbon fibers are oriented so as to be parallel with or perpendicular to the winding shaft, and therefore only a small portion needs to be discarded when cutting out the carbon fiber layer13kof the present embodiment that is disposed such that the orientation direction of the carbon fibers13his perpendicular to the lengthwise direction of the long sides of the back face panel13, and the yield can be improved. On the other hand, in the case of the carbon fiber layer disposed such that the orientation direction of the carbon fibers201is oblique to the lengthwise direction of the long sides of the back face panel200as shown inFIG. 9, a large portion is discarded when the carbon fiber sheet to be used as the carbon fiber layer is cut out from the above-described carbon fiber sheet, and there are cases where the yield decreases.

Note that although the carbon fiber layer13kis configured including the epoxy resin and the carbon fibers13hin the present embodiment, the epoxy resin is merely one example of a thermosetting resin, and another material may be used as long as it is a thermosetting resin.

Also, although the back face panel13includes the first layer13mand the second layer13nthat are both made of magnesium as shown inFIG. 6in the present embodiment, a material other than magnesium can be applied as the material of the first layer13mand the second layer13n. Moreover, either the first layer13mor the second layer13ncan be omitted from the back face panel13.

Also, although the back face panel13is formed such that the planar shape thereof is rectangular in the present embodiment, there is no limitation to the share being rectangular, and effects of the carbon fiber layer13kof the present embodiment can be obtained as long as the shape of the back face panel has at least one pair of long sides.

Also, although the carbon fiber layer13kis provided on the second housing2in the present embodiment, providing the carbon fiber layer13kon the first housing1enables improved flexural strength of the first housing1. Furthermore, providing the carbon fiber layer13kon both the first housing1and the second housing2enables improved overall flexural strength of the notebook PC.

Also, although the carbon fiber layer13kis provided on the back face panel13in the present embodiment, the carbon fiber layer13kcan be provided on the front face panel21as well.

Also, although the carbon fiber layer13kis disposed such that the orientation direction of the carbon fibers13his perpendicular to the lengthwise direction of the long sides of the back face panel13in the present embodiment, there is no limitation to a configuration in which “perpendicular” refers to the orientation direction of the carbon fibers13hand the lengthwise direction of the long sides of the back face panel13forming an exactly 90-degree angle, and somewhat of a margin of error in the angle is possible. In other words, when cutting a carbon fiber sheet of an arbitrary size from a carbon fiber sheet (original roll) in order to prepare the carbon fiber layer13kfor example, there are cases where there is a slight error in the cut size. In this case, it is possible for the orientation direction of the carbon fibers13hand the lengthwise direction of the long sides of the back face panel13to not form an exact 90-degree angle. In the present embodiment, “perpendicular” includes this margin of error in the angle.

The back face panel13is one example of a housing. The carbon fiber layer13kis one example of a carbon fiber layer. The carbon fibers13hare one example of carbon fibers. The first layer13mand the second layer13nare examples of a metal layer. The outer side of the flat plate portion13athat is in contact with the first wall portion13b, and the outer side of the flat plate portion13athat is in contact with the second wall portion13care examples of the long sides of the back face panel13.

The following variations can be applied to the present embodiment.

FIG. 10is a plan view of the configuration of Variation 1 of the back face panel of the present embodiment.FIG. 11is a cross-sectional view taken long line Z-Z inFIG. 10.

A back face panel43shown inFIGS. 10 and 11has the configuration of the back face panel13shown inFIGS. 5 and 6with the further inclusion of projection portions43v,43w, and43x. The projection portions43v,43w, and43xare formed so as to project out from an outer face43fof the back face panel43. In the present embodiment, the projection portions43v,43w, and43xare formed such that the planar shape thereof is rectangular, but this shape is merely one example. The projection portions43v,43w, and43xare formed such that the lengthwise direction of the long sides thereof is perpendicular to the lengthwise direction of the long sides of the back face panel43. The projection portions43v,43w, and43xare provided in order to raise the flexural strength of the back face panel43. The projection portions43v,43w, and43xare formed so as to project out from a principal face43sof the back face panel43, and include an upper face43pat a position that protrudes out from the principal face43s. In the present embodiment, the upper face43pis formed such that the planar shape thereof is rectangular. Note that although a projection portion is provided at three places in Variation 1, this number is merely one example.

Carbon fibers43hare disposed at positions overlapping the projection portions43v,43w, and43x. Also, a carbon fiber layer43kis disposed such that the orientation direction of the carbon fibers43his parallel with the lengthwise direction of the long sides of the projection portions43v,43w, and43x, or more specifically conforms to the lengthwise direction of the upper face43pof the projection portions.

Note that the specific configurations of the carbon fiber layer43kand the carbon fibers43hare similar to the configurations of the carbon fiber layer13kand the carbon fibers13hdescribed with reference toFIGS. 5 and 6. The specific configurations of a first layer43mand a second layer43nare similar to the configurations of the first layer13mand the second layer13ndescribed with reference toFIGS. 5 and 6.

According to this configuration, the flexural strength of the back face panel43is improved due to the flexural strength obtained by the carbon fibers43hand the improvement in flexural strength obtained by forming the projection portions43w,43v,and43x.

Note that although the carbon fiber layer43kis a single layer in the configuration shown inFIGS. 10 and 11, providing multiple carbon fiber layers whose orientation directions are mutually orthogonal enables further improved flexural strength for the back face panel43.

Also, the flexural strength of the back face panel can be improved further by further adding a carbon fiber layer that includes carbon fibers having the same orientation direction as the carbon fiber layer43k. This configuration will be described later with reference toFIG. 12.

Note that in order to clearly show the disposition direction of the carbon fibers13hin the plan views ofFIG. 5and the like, the carbon fibers13hare shown disposed in bands, and the resin is shown with the same width between the bands formed by the carbon fibers13h. However, in actuality the carbon fibers13hare disposed uniaxially, that is to say, in a direction orthogonal to the lengthwise direction of the long sides of the back face panel43, over the entire face in the plan view, without forming disposed portions and non-disposed portion in a band-like configuration. Also, althoughFIG. 10shows a configuration in which the projection portions43v,43w,and43xrise up from resin portions between the carbon fibers, in actuality the carbon fibers13hare not provided independently in a band-like configuration so as to sandwich gap portions with a predetermined width as shown in this figure, but instead the projection portions43v,43w, and43xare formed such that the carbon fibers13hrise up over the entirety of the width direction of the projection portions.

Also, although the projection portions43v,43w, and43xare formed such that the lengthwise direction of the long sides thereof is perpendicular to the lengthwise direction of the long sides of the back face panel43, they may be formed such that the lengthwise direction of the long sides is parallel with the lengthwise direction of the long sides of the back face panel43, or oblique to the lengthwise direction of the long sides of the back face panel43. In each of these configurations, the orientation direction of the carbon fibers43his set perpendicular to the lengthwise direction of the long sides of the back face panel43. Although these configurations do not obtain a greater flexural strength than that of the back face panel43shown inFIGS. 10 and 11, they can obtain a greater flexural strength than that of a back face panel not including projection portions.

Also, although the first layer43mand the second layer43nare provided in Variation 1, the back face panel43can be formed with only the carbon fiber layer43kif the carbon fiber layer43kis formed so as to have a shape equivalent to that of the projection portions43wand the like. This configuration also enables improving the robustness of the second housing2and the back face panel43.

The carbon fiber layer43kis one example of a carbon fiber layer. The carbon fibers43hare one example of carbon fibers. The first layer43mand the second layer43nare examples of a metal layer. The principal face43sis one example of a principal face of the carbon fiber layer or the back face panel. The upper face43pis one example of an upper face of the carbon fiber layer or the back face panel. The outer side of a flat plate portion43athat is in contact with a first wall portion43b, and the outer side of the flat plate portion43athat is in contact with a second wall portion43care examples of the long sides of the back face panel43.

FIG. 12is a plan view of the configuration of Variation2of the back face panel of the present embodiment. Note that in order to clearly show the positions of the carbon fibers,FIG. 12shows a cross section taken along the lengthwise direction of the long sides of the back face panel (corresponding to a cross section taken along line W-W inFIG. 5, for example).

As shown inFIG. 12, a back face panel53includes a first layer53c, a second layer53d, a first carbon fiber layer53e, and a second carbon fiber layer53f. The first layer53cand the second layer53dhave a configuration similar to that of the first layer13mand the second layer13nshown inFIG. 6. The first carbon fiber layer53eand the second carbon fiber layer53fhave a configuration similar to that of the carbon fiber layer13kshown inFIG. 6. The first carbon fiber layer53eincludes first carbon fibers53a. The second carbon fiber layer53fincludes second carbon fibers53b. The second carbon fiber layer53fis disposed between the first carbon fiber layer53eand the second layer53d. The first carbon fiber layer53eand the second carbon fiber layer53fare disposed such that the orientation direction of the first carbon fibers53aand the orientation direction of the second carbon fibers53bare perpendicular to the lengthwise direction of the long sides of the back face panel53. The first carbon fibers53aand the second carbon fibers53bthus are disposed parallel to each other.

This configuration enables further raising the flexural strength of the back face panel53as shown by the solid line in the flexure test results shown inFIG. 13. Specifically, since the number of carbon fibers in the configuration shown inFIG. 12is substantially double that of the configuration shown inFIG. 6and the like, the flexural strength is approximately double the flexural strength of the back face panel13(seeFIG. 7B) shown inFIG. 6and the like, and therefore the configuration shown inFIG. 12is preferable due to the ability to further raise the flexural strength. In this configuration, the two carbon fiber layers53eand53fmay be disposed such that the carbon fibers contained in the respective carbon fiber layers overlap each other or do not overlap each other. Note that the testing method that obtained the flexure test results shown inFIG. 13was similar to the testing method described with reference toFIG. 7B.

Note that although the back face panel53of Variation 2 is configured including the first carbon fiber layer53eand the second carbon fiber layer53fwhose orientation directions are the same direction, a configuration is possible in which in place of the first carbon fiber layer53e, the back face panel53is configured including a carbon fiber layer that includes carbon fibers having an orientation direction that is orthogonal to the orientation direction of the second carbon fibers53b.FIG. 14is a plan view of a back face panel33including first carbon fibers33aand second carbon fibers33bwhose orientation directions are orthogonal to each other.FIG. 15is a cross-sectional view taken long line Z-Z inFIG. 14. The back face panel33shown inFIGS. 14 and 15is configured including a first layer33c, a second layer33d, a first carbon fiber layer33e, and a second carbon fiber layer33f. The first carbon fiber layer33eincludes the first carbon fibers33a. The second carbon fiber layer33fincludes the second carbon fibers33b. The test results regarding the flexural strength of the back face panel33shown inFIGS. 14 and 15are indicated by a broken line inFIG. 13.

The first carbon fiber layers33eand53aand the second carbon fiber layers33fand53fare examples of a carbon fiber layer. The first carbon fibers33aand53eand the second carbon fibers33band53bare examples of carbon fibers. The first layers33cand53cand the second layers33dand53dare examples of a metal layer.

FIG. 16is a plan view of Variation 3 of the back face panel of the present embodiment.FIG. 17is a cross-sectional view taken long line Z-Z inFIG. 16.

Note that the specific configurations of a carbon fiber layer63kand carbon fibers63hare similar to the configurations of the carbon fiber layer13kand the carbon fibers13hdescribed with reference toFIGS. 5 and 6. The carbon fibers63hare oriented in one direction, and are long fibers that are continuous in that direction. The carbon fiber layer63kis configured such that the orientation direction of the carbon fibers63his perpendicular to the lengthwise direction of the long sides of a back face panel63as shown inFIG. 16(i.e., parallel to the lengthwise direction of the short sides of the back face panel63). As shown inFIG. 17, in the vicinity of the pair of long sides of the back face panel63, the carbon fibers63hare bent along a first wall portion63band a second wall portion63c. In other words, portions of the carbon fibers63hare disposed inside the first wall portion63band the second wall portion63c.Note that the carbon fibers63hshown inFIGS. 16 and 17are illustrated schematically.

The specific configurations of a first layer63mand a second layer63nare similar to the configurations of the first layer13mand the second layer13ndescribed with reference toFIGS. 5 and 6.

According to this configuration, it is possible to improve the flexural strength of the first wall portion63band the second wall portion63cof the back face panel63, thus enabling further improvement in the overall flexural strength of the back face panel63.

Also, disposing portions of the carbon fibers63hinside the first wall portion63band the second wall portion63cof the back face panel63improves the strength in the planar direction of a principal face63gand improves the robustness of the second housing2.

Note that the configuration shown inFIGS. 16 and 17also can be applied to the back face panel43shown inFIGS. 10 and 11, the back face panel53shown inFIG. 12, and the back face panel33shown inFIGS. 14 and 15, thus enabling further improving the flexural strength of the respective back face panels.

Also, although the first layer63mand the second layer63nare provided in Variation 3, the back face panel63can be formed using only the carbon fiber layer63k.This configuration enables reducing the weight of the second housing2and the back face panel63. This configuration also enables simplifying the processing and manufacturing of the second housing2and the back face panel63.

The back face panel63is one example of a housing. The carbon fiber layer63kis one example of a carbon fiber layer. The carbon fibers63hare one example of carbon fibers. The first layer63mand the second layer63nare examples of a metal layer. The outer side of a flat plate portion63athat is in contact with the first wall portion63b, and the outer side of the flat plate portion63athat is in contact with the second wall portion63care examples of the long sides of the back face panel63.

The present invention is useful to a housing. The present invention is also useful to an electronic device including a housing.