FASTENING STRUCTURE AND KEYBOARD DEVICE
FIG6 is a cross-sectional view showing an example of the fastening structure of the fourth embodiment  FIG5 is a cross-sectional view showing an example of the fastening structure of the third embodiment
FIG6 schematically shows an example of the fastening structure of the fourth embodiment. In the above-described fastening structure, the effective thread 34 may be entangled with a dark ring 16 of the wood component 10. Wood grown in a temperate zone to a cool zone usually has dark rings 16 and light rings 17 alternately formed due to the difference in the growth rate of the cell wall depending on the season, resulting in annual rings. The dark rings 16 have a higher strength than the light rings 17, and variations due to characteristic differences between the dark rings 16 and the light rings 17 are large. Therefore, when the male screw portion 33 meshes with a portion including the dark ring 16, it is possible to enhance the viscoelastic reversible deformation characteristics.  FIG5 schematically shows an example of the fastening structure of a third embodiment. In the present embodiment, a distance L2 between a to-be-pressed surface 23 of the to-be-fastened component 20 and the contact surface 12 of the wood component 10 with the to-be-fastened component 20 is 2 mm or less. Here, the to-be-pressed surface 23 is a portion where the to-be-fastened component 20 is pressed from the head portion 31 of the screw 30.
cross-sectional view
30
screw
12
contact surface
14
pilot hole
11
surface
20
component
34
effective screw portion
31
head portion
16
dark rings dark ring
10
wood component
23
surface
32
shaft portion
['1. A fastening structure for fastening a to-be-fastened component to a wood component by using a screw, wherein the wood component is made of wood having a specific gravity of 0.08 g/cm 3  to 0.85 g/cm 3  inclusive; the screw has a nominal diameter of 0.8 mm to 3.5 mm inclusive; and the distance between an intermediate position in a longitudinal direction of an effective screw portion, which is the portion where the wood component and a male screw portion formed on a shaft portion of the screw mesh together, and a contact surface of the wood component with the to-be-fastened component is 1 mm to 15 mm inclusive.', '4. The fastening structure according to any one of claims 1 to 3, wherein a distance between a to-be-pressed surface where the to-be-fastened component is pressed from the head portion of the screw and the contact surface is 2 mm or less.', '5. The fastening structure according to any one of claims 1 to 4, wherein the effective screw portion is entangled with a dark ring of the wood component.']