Abstract: The present invention relates to a method of making a preform which can restrain each member from deforming at the time of making, and a method of making an optical fiber with a smaller polarization mode dispersion by utilizing this preform. In the method of making a preform, the collapsing step carried out when making the preform is divided into at least two stages composed of a first step of forming a first collapsed body by collapsing a core rod member and a first cladding tube member, and a second step of forming a new collapsed body by collapsing the first collapsed body and a second cladding tube member. Also, in at least the first step, the collapsed body obtained is elongated, whereas such a plurality of stages of collapsing step and elongation of the resulting collapsed body reduce the outer diameter ratio of the outer member to the inner member to be collapsed, whereby the deformation resulting from the heating at the time of a single collapsing operation and the like is hard to occur.

Abstract: A stencil printing apparatus is provided, which comprises a pressure chamber the wall of which is partly constituted by a flexible sheet member, a mount which is disposed in the pressure chamber opposite to the flexible sheet member and on which an article to be printed is placed, a frame for supporting a stencil between the flexible sheet member and the mount, and a pump for reducing pressure in the pressure chamber, in which the pump for reducing pressure is an air pump which comprises a cylinder connected to the pressure chamber and a piston slidably disposed in the cylinder. Stencil printing can be quickly and readily effect by pressure reduction in the pressure chamber. The printing apparatus can be small-sized, lightweight and simplified as a whole, and is improved in operatability.

Abstract: The disclosed stencil printing apparatus includes, a pressure chamber comprising a first place member on which a sheet to be printed is placed, an airtight elastic frame which is placed on the first plate to surround the sheet, and a second plate member which is placed on the elastic frame and supports a stencil opposite to the sheet; a resilient air chamber which is layered below the first plate member of the pressure chamber and communicates with the pressure chamber; and a check valve which allows air to be exhausted from the air chamber but inhibits the air chamber from sucking air from the apparatus outside.

Abstract: An electrical connector 1 comprises a mediate circuit board assembly 4, a housing 2, and a plurality of contacts 3. The mediate circuit board assembly 4 has a plurality of signal paths, to which signal cables 5 are connected, and the housing 2 houses this mediate circuit board assembly 4. The contacts 3 are retained in the housing 2 and connected to the signal paths of the mediate circuit board assembly 4, which is housed in the housing 2. Two double-sided circuit boards, each having at least the signal paths formed on the front face and a grounding path formed on the rear face, constitute the mediate circuit board assembly 4 when these two double-sided circuit boards are abutted with each other, connecting the grounding paths of their rear faces.

Abstract: A thermal printing system which makes printing by selected ones of a plurality of thermal dot generating means being actuated at selected dot areas in a matrix of dot areas according to input formation for printing provides printing in either normal image forming mode or reversed mirror image forming mode by the relative order of sequential decoding of the input information for printing and of sequential actuation of the thermal dot generating means according to the decoded printing information signal being switched over in two ways.