A panel which includes, among protrusions protruding from a predetermined reference surface, flat sections being flush with the reference surface, and recesses being recessed from the reference surface, the protrusions, and the flat sections or recesses, wherein; when the panel includes the flat sections, the entire periphery of each of the protrusions is surrounded by the flat sections, and the entire periphery of each of the flat sections is surrounded by the protrusions, while when the panel includes the recesses, the entire periphery of each of the protrusions is surrounded by the recesses, and the entire periphery of each of the recesses is surrounded by the protrusions.
1. A panel which is made of metal, the panel comprising,
protrusions protruding from a predetermined reference surface and having an upper surface section; and
flat sections being flush with the reference surface, wherein:
an entire periphery of each of the protrusions not including a corner section is surrounded by the flat sections, and an entire periphery of each of the flat sections is surrounded by the protrusions;
each of the corner sections of respective adjacent protrusions is connected via a bridge having a flat top upper surface or having a circular arc section;
a protrusion side inclined surface which is not vertical to the predetermined reference surface is formed on a peripheral portion of the protrusions;
a corner section inclined surface which extends from the corner sections toward the reference surface is formed; and
(S 3 +S 4 )/(S 1 ) is equal to or less than 1.0, where:
S 1 is a total area of the upper surface sections of the protrusions;
S 3 is a total area of the flat top upper surface of the bridges; and
S 4 is a total area of the protrusion side inclined surface and the corner section inclined surface.
2. The panel according to claim 1 , wherein when viewed from a front, the protrusions, and the flat sections are alternately arranged along a widthwise direction and a lengthwise direction orthogonal to this widthwise direction.
3. The panel according to claim 1 , wherein when viewed from a front, each of the protrusions has a hexagonal shape, and each of the flat sections has a triangular shape.
4. The panel according to claim 1 , wherein when viewed from a front, the protrusions and the flat sections both have a quadrangular shape.
5. The panel according to claim 1 , wherein a frame section is provided along a periphery of the panel, which includes all of the protrusions, and the flat sections.
6. A panel which is made of a metal, the panel comprising,
protrusions protruding from a predetermined reference surface and having an upper surface section; and
recesses being recessed from the reference surface and having a bottom surface section, wherein:
an entire periphery of each of the protrusions not including a corner section is surrounded by the recesses, and an entire periphery of each of the recesses is surrounded by the protrusions not including the corner section;
each of the corner sections of respective adjacent protrusions is connected via a bridge having a flat top upper surface or having a circular arc section, the flat top upper surface or the circular arc section of the bridge being provided apart from a plane containing the upper surface sections of the protrusions toward the predetermined reference surface;
a protrusion side inclined surface which is not vertical to the predetermined reference surface is formed on a peripheral portion of the protrusions, and a recess side inclined surface which is not vertical to the predetermined reference surface is formed on a peripheral portion of the recesses;
a corner section inclined surface which extends from the corner sections toward the reference surface is formed; and
(S 3 +S 4 )/(S 1 +S 2 ) is equal to or less than 1.0, where:
S 1 is a total area of the upper surface sections of the protrusions;
S 2 is a total area of the bottom surface sections of the recesses;
S 3 is a total area of the flat top upper surface of the bridges; and
S 4 is a total area of the protrusion side inclined surface, the recess side inclined surface, and the corner section inclined surface.
7. The panel according to claim 6 , wherein when viewed from a front, the protrusions, and the recesses are alternately arranged along a widthwise direction and a lengthwise direction orthogonal to this widthwise direction.
8. The panel according to claim 6 , wherein when viewed from a front, each of the protrusions has a hexagonal shape, and each of the recesses has a triangular shape.
9. The panel according to claim 6 , wherein when viewed from a front, the protrusions and the recesses both have a quadrangular shape.
10. The panel according to claim 6 , wherein:
when the protrusion side inclined surface and the recess side inclined surface are viewed on a cross-section perpendicular to the reference surface, the protrusion side inclined surface and the recess side inclined surface are linearly and continuously connected; and
an inclination angle of the protrusion side inclined surface and an inclination angle of the recess side inclined surface are same.
11. The panel according to claim 6 , wherein:
planar shapes and planar dimensions of the protrusions and the recesses are same.
12. The panel according to claim 6 , wherein:
a protruding dimension of the protrusions and a recessing dimension of the recesses respectively in a direction perpendicular to the reference surface are same.
13. The panel according to claim 6 , wherein a frame section is provided along a periphery of the panel, which includes all of the protrusions, and the recesses.