Linear scale electric meter with cylindrical internal magnet and two arc-shaped auxiliary yokes

An electric meter providing a substantially linear scale, comprising:

• a cylindrical internal magnet having a central axis and being diametrically magnetized so as to have N and S poles which are oriented such that a straight line connecting both said N and S poles intersects with said central axis of said internal magnet at right angles thereto.
• first and second separated circular arc-shaped non-magnetized auxiliary yokes made of soft-iron and located opposite to each other about the outer periphery of said cylindrical internal magnet and oriented such that a straight line therebetween intersects the straight line connecting the N and S-pole arrangement of said cylindrical internal magnet, said non-magnetized auxiliary yokes being spaced a prescribed distance from the outer periphery of said cylindrical internal magnet,
• said non-magnetized auxiliary yokes each having first and second tip end portions, the first tip end portions of said yokes being spaced from each other and being located on one side of a further straight line passing through the central portions of said yokes and said central axis of said cylindrical internal magnet, and the second tip end portions of said yokes being spaced from each other and being located on the other side of said further straight line,
• a movable coil, and
• means for turnably supporting said movable coil so as to permit said movable coil to swing substantially in a yoke-free position in the spaces between said tip end portions of said non-magnetized auxiliary yokes about said central axis in a magnetic field produced in the space between said first tip end portions of said first and second non-magnetized auxiliary yokes and one pole of said cylindrical internal magnet and in the space between said second tip end portions of said first and second non-magnetized auxiliary yokes and the other pole of said cylindrical internal magnet.