| 主权项 |
1. A mechanism for controlling an initial melt level in a single crystal pulling apparatus which controls a position of a melt surface in order to pull single crystals from the melt surface using the Czochralski method, the mechanism comprising:
an optical recording device which obtains image information by photographing a real image of a furnace internal structural object and a reflected image of the furnace internal structural object that is reflected on the melt surface in a state where a single crystal is not present; and a processing device which, taking a value that is based on the real image as a reference value, controls the position of the melt surface based on a relationship of a position of the reflected image, a size of the reflected image, a distance between the reflected image and the real image, or amounts of changes thereof to the position of the melt surface or the amount of movement of the melt surface, the relationship being calculated in advance from the image information; wherein the furnace internal structural object is a member that is provided at a position facing the melt surface inside a crucible and is fixed such that the shape, dimensions, and position thereof remain constant and unchanged relative to the movement in the vertical direction of the crucible during the pulling of the single crystal, and the furnace internal structural object is a heat shield having a circular shape, a center point of an edge of the heat shield is calculated by a circular approximation, a center point of a reflected image of the edge of the heat shield that is reflected on the melt surface is calculated by a circular approximation, and the calculated center points are used as points for measurements in order to specify the distance between the real image and the reflected image. |
