Heating roller apparatus with precise temperature measurement

A heating roller apparatus comprising:

• a roller member having a cylindrical wall and defining a space in the inside thereof and an annular groove in said cylindrical wall;
• a rotatably supported drive shaft, means rigidly and concentrically supporting one end of the roller member on an end of the drive shaft;
• heat source means stationarily positioned in the inner space of the roller member for heating the cylindrical wall, stationary flange means having a support extending into said inner space for supporting said heat source means, said flange means being positioned adjacent the other end of said roller member,;
• and a temperature sensor having a measuring probe stationarily positioned in the annular groove of the cylindrical wall for measuring a temperature of the cylindrical wall of the roller member, said annular groove being located at a position adjacent to said other end of said roller member and having an opening on the outer surface of said cylindrical wall, and two adjacent circumferentially extending wall faces which penetrate into said cylindrical wall and are substantially perpendicular to the axis of said roller member, said wall faces being spaced from said measuring probe of said temperature sensor;
• and a metal covering of low thermal capacity and high thermal conductivity extending from said flange means over said opening of said annular groove, said covering facing said opening at a determined distance therefrom and being exposed thereto.