Rotary encoder with multiple calibration points

An optical rotary encoder, comprising:

• a rotatable disk;
• an index channel disposed on the rotatable disk, including a single circumferentially extending row of at least two index points located on equally-spaced radii, each index point encoding information specifying an angular position of the index point along a circumference of the rotatable disk;
• a first light emitting device disposed to illuminate the index channel;
• a first light receiving device disposed to receive the illuminated index channel;
• a data channel disposed on the rotatable disk, for measuring an angular displacement, including a single circumferentially extending row of data pulses located on equally-spaced radii, each data pulse specifying an incremental angular displacement of the rotatable disk;
• wherein the data channel occupies the same circumferentially extending row on the disk as the index channel, so that index points indicating angular position, and the data pulses specifying incremental angular displacement, are contained within the same row;
• a second light emitting device disposed to illuminate the data channel;
• a second light receiving device disposed to receive the illuminated data channel;
• a signal processing device coupled to the first light receiving device and the second light receiving device for converting signals from the first light receiving device into an index signal, and converting signals from the second light receiving device into an angular rotation signal;
• and
• a calibration mechanism coupled to the signal processing device, for calibrating an angular output of the optical rotary encoder by reading the index signal.

An angular position indicator, comprising:

• a rotational input mechanism;
• a rotary encoder coupled to the rotational input mechanism;
• a rotatable disk within the rotary encoder;
• an index channel disposed on the rotatable disk, including a single circumferentially extending row of at least two index points located on equally-spaced radii, each index point encoding information specifying an angular position of the index point along a circumference of the rotatable disk;
• a first light emitting device disposed to illuminate the index channel;
• a first light receiving device disposed to receive the illuminated index channel;
• and
• a signal processing device coupled to the first light receiving device for converting signals from the first light receiving device into an index signal;
• a data channel disposed on the rotatable disk, for measuring an angular displacement, including a single circumferentially extending row of data pulses located on equally-spaced radii, each data pulse specifying an incremental angular displacement of the disk;
• wherein the data channel occupies the same circumferentially extending row on the disk as the index channel, so that index points indicating angular position, and the data pulses specifying incremental angular displacement, are contained within the same row;
• a second light emitting device disposed to illuminate the data channel;
• a second light receiving device disposed to receive the illuminated data channel;
• and
• wherein the signal processing device is coupled to the second light receiving device and converts signals from the second light receiving device into a an angular displacement signal.

An apparatus including an input device with an angular position indicator, comprising:

• a computer system;
• the input device coupled to the computer system;
• a rotary encoder within the input device;
• a rotatable disk within the rotary encoder;
• an index channel disposed on the rotatable disk, including a single circumferentially extending row of at least two index points located on equally-spaced radii, each index point encoding information specifying an angular position of the index point along a circumference of the disk;
• a first light emitting device disposed to illuminate the index channel;
• a first light receiving device disposed to receive the illuminated index channel;
• and
• a signal processing device coupled to the first light receiving device for converting signals from the first light receiving device into an index signal;
• a data channel disposed on the rotatable disk, for measuring an angular displacement, including a single circumferentially extending row of data pulses located on equally-spaced radii, each data pulse specifying an incremental angular displacement of the rotatable disk;
• wherein the data channel occupies the same circumferentially extending row on the disk as the index channel, so that index points indicating angular position, and the data pulses specifying incremental angular displacement, are contained within the same row;
• a second light emitting device disposed to illuminate the data channel;
• a second light receiving device disposed to receive the illuminated data channel;
• wherein the signal processing device is coupled to the second light receiving device and converts signals from the second light receiving device into a an angular displacement signal.