Abstract: The liquid crystal cell (30) for the optical change-over switch comprises a pair of transparent substrates (1), a pair of transparent flat electrodes (2) provided on the respective opposing surfaces of the substrates, orientation control films (3) provided on the flat electrodes (2), two pair of comb shaped electrodes (33) respectively provided on the orientation control films (3), and a ferroelectric liquid crystal layer (4) confined between the substrates (1). The optical incidence plane (31) to the cell (30) is so selected that the plane (31) is away from the helical axes (9) of the ferroelectric liquid crystal in the cell (30) in the order of somewhat greater than the tilt angle (.theta..sub.t) of the ferroelectric liquid crystal.

Abstract: A constant pressure boiling cooling system including evaporators, a condenser and a liquid refrigerant sump, wherein the evaporators and the condenser are arranged substantially horizontally in side-by-side relation, and the first communicating tubes connect the upper portions of the evaporators to the upper portions of the condenser respectively, and the second communicating tubes connect the lower portions of the evaporators to the lower portions of the condenser respectively.

Abstract: A constant pressure type ebullient cooling equipment has a liquid receiver at a position higher than a condenser. The liquid receiver is connected with a vaporizer containing a liquid refrigerant by a coupling pipe. A valve and a device for opening or shutting the valve are disposed at an upper part of the liquid receiver. When refrigerant vapor produced in the vaporizer is introduced into the condenser, refrigerant liquid in the vaporizer moves to the liquid receiver. The condenser and the liquid receiver are connected by a deaerating pipe. Non-condensable gases such as air contained in the cooling equipment and the refrigerant enter the liquid receiver, and are emitted through the valve. As a result, the interior of the cooling equipment is held under a substantially constant pressure.

Abstract: An apparatus for cooling a heat generating member by utilizing the latent heat of vaporization of a boiling refrigerant, having a cooling vessel including an evaporator section containing the boiling refrigerant and adapted to transmit the heat generated by the heat generating member to the refrigerant, and a condenser section for liquefying the gasified refrigerant; a liquid refrigerant reservoir open at its upper end and adapted to store a body of the refrigerant which does not directly take part in a cooling operation while the cooling operation is being performed; and a communication means for communicating the cooling vessel with the liquid refrigerant reservoir, the cooling vessel and the communication means being filled with the boiling refrigerant.