PURPOSE: To increase the deposition speed and to shorten the depositing time by changing the flow velocity of a raw gas at the outlet of a raw gas feed pipe with time while keeping the raw gas flow rate constant.
CONSTITUTION: A burner used to produce a porous glass perform is shown is the figure as a sectional view, and a raw gas feed pipe of the burner is shown in the figure as a profile. The raw gas feed pipe 11 provided in the burner 10 consists of an outer pipe 12 and a rod-shaped inclusion 13 in the pipe 12, and the cross-sectional area of the tip is slightly changed axially. The tip 17 of the pipe 12 is tapered and contracted, and the inclusion 13 has a taper at the tip 14. When the insert 13 is moved in the axial direction of the pipe 11, the area of the raw gas outlet at the tip of the pipe 11 is changed by the relative positional relation between the tip 17 of the pipe 12 and the tip 14 of the inclusion 13. Accordingly, the flow velocity of the raw gas is changed by moving the inclusion 13 in the axial direction.
| JPH0429291 | LIGHT TRANSMISSION PLATE |
| JPH04267229 | MANUFACTURE OF LIGHT GUIDE |
| JP2000149637 | BACK LIGHT DEVICE PROVIDED WITH EXPANDED PART |
KUMADA TETSUYA
KOMURA YUKIO
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