Progressive plotter with brake for supply roll

A friction brake for use in a device advancing sheet material from a supply roll onto a take-up roll, said brake comprising:

• a shaft having a longitudinally extending central axis and being slidably positioned within an opening in a support and having at one end axial retention means and at its other end a means axially biasing said shaft in the direction from said one end toward said other end;
• a journalling part rotatably supported on said shaft adjacent said axial retention means and having an outer face oriented orthogonally to e aid shaft axis, said journalling part being adapted to be nonrotatably connected with one end of a supply roll such as aforesaid with said shaft aligned with the axis of said supply roll so that said journalling part rotates with said supply roll;
• a reverse bias member rotatably supported on said shaft and having opposed first and second faces extending orthogonally to said shaft axis;
• a friction member rotatably supported on said shaft and having third and fourth faces extending orthogonally to said shaft axis, said friction member third face being engagable with said journalling part outer face and said friction member fourth face being engagable with said reverse bias member first face;
• a bearing member positioned adjacent said support and being engagable with said reverse bias member second face;
• and
• means for resiliently resisting rotation of said reverse bias member in one direction from a given neutral position, said one direction being the direction in which said supply roll rotates relative to said shaft as sheet material is pulled from it.

In a progressive plotter where sheet material is advanced from a supply roll to a take-up roll, the combination comprising:

• a table providing a support surface;
• means supporting a take-up roll of paper and a supply roll of paper adjacent said support surface so that the paper passes from said supply roll over said support surface to said take-up roll;
• a take-up motor for rotating said take-up roll;
• a sensor sensing the displacement of the paper relative to said support surface during a paper advancement;
• a control means responsive to said sensor for stopping said take-up motor at the end of an advancement;
• and
• a brake releasably coupled with said supply roll by friction means for applying a reverse bias to said supply roll during an advancement to resist unwinding of the paper from said supply roll and to tension the paper existing between said supply roll and said take-up roll, and for continuing to apply a reverse bias to said supply roll at the end of an advancement after said take-up motor is stopped.

In a progressive plotter having unidirectional paper movement between a supply roll and a take-up roll, a friction brake associated with said supply roll which friction brake comprises:

• a shaft having at one end a head and being threaded at its other end;
• said shaft threaded end passing through an opening in a support plate and being nonrotatably yet slidingly supported within said opening;
• a journalling part rotatably supported on said shaft between said head and said support plate, said journalling part having means by which it may be selectively coupled to a plug inserted within a supply roll;
• a friction washer rotatably supported on said shaft and being interposed between said journalling part and said support plate;
• a reverse bias arm having at one end a circular portion rotatably supported on said shaft and being connected at its other end to said support plate by a tension spring;
• a thrust bearing interposed between said reverse bias arm circular portion and said support plate;
• a compression spring located adjacent said threaded end of said shaft and being oriented coaxially about said shaft;
• a take-up nut and washer concentrically supported on said threaded end of said shaft and limit means cooperating with said reverse bias arm to limit its rotation;
• and
• wherein said compression spring is interposed between said support plate and said take-up nut and washer.