Abstract: A hand-held marking device comprises an electrically actuated writing head for making marks on a writing surface and a sensor for detecting when the writing head is moving in any direction in a plane parallel to the surface. The device includes a mechanism for causing the head to be actuated when the sensor detects relative movement of the writing head and the surface. The writing head can be arranged to be able to make a plurality of different types or sizes of marks on a writing surface, in which case a mechanism is provided for selecting which of the different mark types or sizes is to be made.

Abstract: This invention relates to a piezoelectric valve for controlling fluid flow and, more particularly to such a valve which is neither solenoid or servo assisted. In this specification and claims, reference to fluid(s) includes both liquid(s) and gas(es). One particular form of piezoelectric valve for controlling fluid flow comprises a housing, a cavity within the housing, piezoelectric valve disc element and a valve seat, inlet and outlet ducts for leading fluid into and out from the cavity and disposed on opposite sides of the valve disc element and means for supporting the valve disc element at a central region of the element with the peripheral region of the disc disposed for cooperation with the valve seat so that upon actuation of the element by a voltage applied thereto, the periphery of the disc is displaceable and at least a portion of a peripheral region of the disc serves to control fluid flow between the inlet and outlet ducts.