Patent ID: 8396186

Claim:
A dental x-ray photographing device comprising: an x-ray source that emits x-ray beam to an object; an x-ray imaging means for detecting the x-ray beam which is emitted from the x-ray source and passes through the object; a supporting means for supporting the x-ray source and the x-ray imaging means; a rotating means for rotating the supporting means around a vertical axis to rotate the x-ray source and the x-ray imaging means around the object in a horizontal direction; a sliding means for linearly moving the x-ray imaging means in a direction along a photo receiving surface; a control device that controls an operation of the rotating means and an operation of the sliding means; and an image processing means for processing a projection image which is obtained by the x-ray imaging means, wherein the control device executes: a first sliding step of causing the sliding means to move the x-ray imaging means to a first detection position where the x-ray beam that passes through a first region of the object is detected; a first imaging step of causing the x-ray imaging means to obtain a first set of projection images which go through the first region while the x-ray source and the x-ray imaging means are rotated by the rotating means; a second sliding step of causing the sliding means to move the x-ray imaging means to a second detection position where the x-ray beam that passes through a second region of the object is detected; and a second imaging step of causing the x-ray imaging means to obtain a second set of projection images which goes through the second region while the x-ray source and the x-ray imaging means are rotated by the rotating means, the image processing means executes a pasting-and-composing step of pasting and composing projection images among the first set of projection images and the second set of projection images, respectively, having the same phase angle of the supporting means, the sliding means comprises origin-position detecting means for detecting an origin position of the x-ray imaging means, the x-ray imaging means is moved linearly from the predetermined origin position to the first detection position and the second detection position, respectively, in the first sliding step and the second sliding step, the origin-position detecting means comprises: a light blocking plate that is moved linearly together with the x-ray imaging means by the sliding means; and an optical sensor that detects a position of an end of the light blocking plate, and a time point at which the end of the light blocking plate passes the optical sensor in a forward direction is detected as the origin position.