Digital ruler with low-friction sliding contact

A digital ruler comprising a ruler body assembly having a base plane positionable against a work surface and a sliding position indicator, the sliding position indicator extending through and moving along a slot in the ruler body assembly and positionable at a plurality of unique measuring positions along the direction of the measuring axis of the digital ruler,

• the ruler body assembly comprising:
• a housing comprising a cover portion;
• a first set of X-Y misalignment constraint surfaces that extend along the direction of the measuring axis;
• and
• a printed circuit board assembly including:
• a printed circuit board,
• a measuring track portion comprising a plurality of measuring scale contacts arranged along a first surface of the printed circuit board to provide a measuring scale contact configuration that extends along the measuring axis, and
• a signal processing and display circuit configured to detect unique sets of measuring scale contacts that are electrically connected to the sliding position indicator depending on its position along the measuring axis, wherein each unique set of electrically connected measuring scale contacts is indicative of a corresponding unique measuring position along the measuring axis;
• and
• a sliding position indicator comprising:
• an indicator body including a second set of X-Y misalignment constraint surfaces, wherein each member of the second set of X-Y misalignment constraint surfaces is located opposing a proximate member of the first set of X-Y misalignment constraint surfaces;
• an indicator contact that comprises a conductive material configured to provide a plurality of conductively connected contact pads and a compliant portion configured to force the contact pads against the measuring scale contacts to connect them to define the unique sets of electrically connected measuring scale contacts,
• wherein:
• hypothetical orthogonal coordinate directions may be defined relative to the digital ruler such that an X direction is parallel to the direction of the measuring axis, a Y direction is orthogonal to the X direction and approximately parallel to the base plane, and a Z direction is normal to an X-Y plane that is parallel to the X and Y directions;
• the first and second sets of X-Y misalignment constraint surfaces are arranged to constrain a maximum misalignment of the sliding position indicator relative to the ruler body assembly for misalignments in the X-Y plane, as the sliding position indicator is moved along the slot;
• and
• the sliding position indicator comprises an instrument receiving feature formed in an external portion of the indicator body that extends outside the ruler body assembly from the slot, the instrument receiving feature configured to receive an instrument tip that is positioned against the work surface and operably engage with the instrument tip such that the instrument tip moves the sliding position indicator in conjunction with the instrument tip, when the instrument tip is moved along the direction of the measuring axis.