Angle detection mechanism and angle detection system

An angle detection system comprising:

• an angle detection mechanism to detect a rotation angle of a rotation body by using a plurality of detection units which have different output characteristics;
• an angle determination unit to select a selection detection unit using an output value among the plurality of the detection units, the angle determination unit to determine an angle position of the rotation body based on the output value of the selection detection unit, wherein
• the angle detection mechanism includes
• a first detection unit to cause a first output value to constantly change in response to an angle change of the rotation body in the entire region of a specific rotation range of the rotation body which is previously defined, the first detection unit to set a change quantity of the first output value relative to the angle change that is predetermined in a first rotation region that is a part of the specific rotation range to be greater than a change quantity in a rotation region of the specific rotation range other than the first rotation region that is a non-first rotation region of the specific rotation range, and
• a second detection unit to cause a second output value to constantly change in response to an angle change of the rotation body in the entire region of the specific rotation range, the second detection unit to set a change quantity of the second output value relative to the angle change that is predetermined in a second rotation region defined to include a rotation region in the specific rotation range different from the first rotation region to be greater than a change quantity in a rotation region of the specific rotation range other than the second rotation region that is a non-second rotation region of the specific rotation range,
• the second rotation region is set to include a rotation region of a specific rotation direction of the rotation body relative to the first rotation region,
• the angle determination unit is to
• switch the selection detection unit from the first detection unit to the second detection unit at a first switching angle in response to a rotation of the rotation body from the first rotation region in the specific rotation direction, and
• switch the selection detection unit from the second detection unit to the first detection unit at a second switching angle in response to the rotation of the rotation body from the second rotation region in a direction opposite to the specific rotation direction, and
• the first switching angle is set to be in the specific rotation direction relative to the second switching angle.