Pressure controlled activating switch for a hand held tool
The present application is a continuation application of my application Ser. No. 07/940,900 filed as PCT/CH92/00038, published as WO91/12612, Aug. 22, 1991, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a pressure switch, especially for writing tools and other tools of similar form. 
     1. Background of the Invention 
     There are various pressure switches for these kinds of tools but they have the disadvantage that the switch actuating pressure must be applied to a restricted place on the tool. 
     The object of this invention is to provide a pressure switch that does not have the aforesaid disadvantage of the prior art and is simple and cheap. 
     2. Brief Description of the Invention 
     The invention provides a pressure operated switch for writing tool or the like having an elongated flexible barrel. An axial support member is carried within the barrel and protrudes from an end thereof. A plurality of gliding elements surround the axial support member and are mounted within the barrel for axial movement. A plurality of inserting elements are carried between the gliding elements and are moveable radially in the barrel. Also included is a connecting means axially moveable within the barrel and operatively disposed to activate a switch element. The gliding elements, inserting elements and connecting means are arranged within the barrel so that radial pressure on the barrel causes radial movement of the inserting elements which in turn causes axial movement of one or more of the gliding elements which in turn causes axial movement of the connecting means and activation of the switch element. Thus, radial inward movement of the barrel along an extended area thereof creates an axial movement which activates the switch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagrammatic partially sectional view of one embodiment of the invention. 
     FIG. 2 is a schematic diagrammatic partially sectional view of another embodiment of the invention. 
     FIGS. 3-6 are side elevational views showing details of elements and subassemblies of the FIG. 1 embodiment of the invention. 
     FIG. 7 is a top plan view showing details of the inserting elements of the present invention. 
     FIGS. 8A-8C are schematic diagrammatic partially sectional views of yet another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the FIG. 1 (and FIGS. 3-7) embodiment of the invention a writing tool, generally indicated at (20), has an elongated flexible cover or barrel (8). An axial support member (1) is carried within the barrel and protrudes from one end to create the illustrated pen point (1A). Surrounding the axial support member (1) are a plurality of gliding elements (3), which are shown as balls (3, 3a). A plurality of inserting elements (4, 4a, 4b, and 4c) are carried between the flexible barrel (8) and pairs of balls (3, 3a). The balls (3) which are pressed together by spring means (5) are held between a lower support (24) and a clamp element (7) engaging the upper ball (3). A means such as a cylinder (26) slidably mounted on support (1) is connected at one end to clamp element (7), and at the other end to a leading part (12) which in turn is connected (through a means (27)) to a contact element (9) which operates to close (or open) a signal input device element (6) such as a pressure counter, a time counter, an acoustical device, an electrical device, a visual display, a valve or a mechanical switch. 
     The operation of the pressure switch will be described for the writing tool described in FIG. 1. By radially pressing the flexible cover (8) along its length adjacent any of the inserting elements (4, 4a, 4b or 4c) the element (4, 4a, 4b or 4c) is moved between an adjacent pair of balls (3). The side pressure applied to an element (4) separates an adjacent pair of balls (3) and creates an upward axial linear movement of cylinder (26), causing leading part (12), means (27) and contact element (9) to move upward and activate signal input device element (6). 
     The relative position of input device element (6) and contact element means (9) may be adjusted by a slider (11) (FIG. 1) or by a button (10) (FIG. 2). 
     Referring now to FIG. 2, there is shown another embodiment of the invention. In this case, a cylinder (2) slidably surrounds axial support (1). The balls (3, 3a) are slidably mounted on support (2), except for the top ball (3) which is fixed to the cylinder (2) at a clamp element (7a). Cylinder (2) is slidably mounted in a lower support (24a). 
     According to the FIG. 2 embodiment, side pressure on barrel (8) results in radial movement of inserting elements (4, 4a, 4b  or 4c) which in turn results in axial movement of balls (3, 3a) and cylinder support (2) and contact element (9) which is carried thereon to activate signal input device element (6). Additionally, it can be used for the interruption of the writing process or for marking when the pressure reaches an adjustable degree. 
     The pressure switch may be used for teaching purposes or to make the switching easier. 
     While a preferred embodiment of the invention involves the use of a spring (5) for normally holding the balls (3, 3a) in contact, the same result can be achieved by using magnetically attracted balls (3, 3a) which hold the balls together i.e. as shown in FIGS. 8A-8C.