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AssigneeKomatsu Denshi Kinzoku Kabushiki Kaisha
InventorsMasato Moriya, Takayuki Hanamoto, Hiroshi Monden, Toshio Hayashida, Toshirou Kotooka
Estimating the term…
A melt level or the gap between a melt surface and a heat shield is measured accurately irrespective of how the melt surface is. A laser beam (2) from a range-finding unit (8) is reflected by a scanning mirror (24) and projected on a melt surface (3) through an entrance window (18) and a quartz prism (20) in a chamber (17) of a puller. After specular reflection, the beam forms a measurement spot (31) in the bottom of a heat shield (16) and scatters. Part of the scatter, after specular reflection at the melt surface (3) (secondary reflection), passes through the prism (20), the entrance window (18) and the scanning mirror (24) to the range-finding unit (8). The range-finding unit (8) carries out triangulation using the distance between a laser source and a photodetector therein, and the angle of incidence and the angle of the received laser beam.
A level measuring apparatus, comprising a mechanism having a laser source and a photodetector in prescribed positions of a CZ furnace, for projecting a laser beam emitted from the laser source onto a melt surface or a prescribed in-furnace member and receiving the laser beam (primary reflection) directly reflected from the melt surface or the prescribed in-furnace member by the photodetector;
A CZ type single crystal puller, comprising a mechanism having a laser source and a photodetector in prescribed positions of a CZ furnace, which projects a laser beam emitted from the laser source onto a melt surface or a prescribed in-furnace member and receives the laser beam (primary reflection), which is directly reflected from the melt surface or the prescribed in-furnace member, by the photodetector, and a mechanism which projects the laser beam reflected from the melt surface onto the bottom of the prescribed in-furnace member to receive the laser beam (second reflection), which is finally reflected from the melt surface, by the photodetector through the sequence of “the melt surface→the bottom of the prescribed in-furnace member→the melt surface”.
In a CZ type single crystal puller provided with a melt level measuring apparatus having a laser source for projecting a laser beam onto a melt surface and a photodetector for receiving the laser beam reflected from the melt surface that are placed in prescribed positions of a CZ furnace, which measures a melt level of the melt surface in the CZ furnace based on the principle of triangulation, a method for improving a probability of receiving a laser beam in the photodetector by reflecting the laser beam reflected from the melt surface on the bottom of a heat shield and guiding the laser beam to the photodetector through a prescribed route.
In a melt level measuring apparatus provided with a laser source and a photodetector in prescribed positions of a CZ furnace, which projects the laser beam emitted from the laser source onto a melt surface, receives the laser beam reflected from the projected spot by the photodetector, and measures a melt level of the melt surface in the CZ furnace based on the principle of triangulation, a method for making to project the laser beam reflected from the melt surface onto the bottom of a heat shield and making to receive the beam reflected from the bottom through the melt surface, thereby providing a more appropriate melt level measuring apparatus or switching to a melt surface-heat shield gap measuring apparatus.
A reflector for a level measuring apparatus, comprising a mirror plate which reflects a laser beam and allows heat rays to pass through and a heat rays absorbing plate which is disposed on the back side of the mirror plate, the mirror plate and the heat rays absorbing plate being paired in a mutually slidable state.
A reflector for a level measuring apparatus, comprising a first mirror plate which reflects a laser beam and allows heat rays to pass through and a second mirror plate which is disposed on the back side of the first mirror plate and allows visible light to partly pass through, the first mirror plate and the second mirror plate being paired in a mutually slidable state.
Dependencies are inferred from the claim text.