TWO-DIMENSIONAL CODE READING DEVICE, TWO-DIMENSIONAL CODE READING METHOD, METHOD OF CONTROLLING MANUFACTURING HISTORY INFORMATION OF MEMBER HAVING SUBSTANTIALLY CIRCULAR SECTION ORTHOGONAL TO THE CENTRAL AXIS THEREOF, AND METHOD OF MANUFACTURING THE MEMBER USING THE CONTROL METHOD

摘要

[Problem to be Solved] Provided are a two-dimensional code reading device and a two-dimensional code reading method for reading a two-dimensional code carved in a member having a substantially circular section orthogonal to the central axis thereof, as well as a method of controlling manufacturing history information using the reading device and a method of manufacturing the member using the control method. [Solution] A concave portion 11 carved in the member on which a two-dimensional code 10 is formed has a pair of a first inclined portion 12 and a second inclined portion 13 which are inclined so as to form an angleβwith respect to a normal-line direction R of a surface of the member. A two-dimensional code reading device 20 is provided with image pickup means 22 which receives light reflected from either of the first inclined portion 12 and the second inclined portion 13 in a direction forming an angleθsatisfying expression (1) with respect to the normal-line direction R, and illumination means 21 which irradiates either of the inclined portions from a direction forming an angleαsatisfying expression (2) with respect to the normal-line direction R: 30°≰θ≰35°  (1)Δθ=θ−180°+α+2β  (2) whereβis less than 90°,Δθis not less than−10° but not more than 10°, andθandαare angles in a turn direction reverse to a turn direction at which either of the inclined portions forms the angleβwith respect to the normal-line direction R.