Position detection unit, and lens apparatus, image pickup apparatus, and lens command apparatus each including the position detection unit

Abstract

A position detector of a mover relative to a stator includes: an output unit outputting displacement signals including a first signal in a first period and a second signal in a period longer than the first period, while switching among the displacement signals, according to a change in the position of the mover; and a deriver that derives an absolute position as the position of the mover based on the displacement signals, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the mover, wherein in deriving the absolute position, the signal output unit outputs the first signal, the second signals, and the first signal in this order, and the deriver derives the absolute position based on the displacement signals, in deriving the relative position, the position deriver derives the relative position based on the first signal and the second signals.

What is claimed is: 
     
         1 . A position detection apparatus for detecting a position of a movable member relative to a fixed member, the position detection apparatus comprising:
 a signal output unit that outputs a plurality of displacement signals including a first signal that changes in a first period and a second signal that changes in a period longer than the first period, while switching among the plurality of displacement signals, in accordance with a change in the position of the movable member relative to the fixed member; and   a position deriver that derives an absolute position as the position of the movable member relative to the fixed member based on the plurality of displacement signals output from the signal output unit, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the movable member relative to the fixed member, wherein   in deriving the absolute position,
 the signal output unit outputs the first signal, a plurality of the second signals, and the first signal in this order, and 
 the position deriver derives the absolute position based on the plurality of displacement signals, 
   in deriving the relative position,
 the position deriver derives the relative position based on the first signal and the plurality of the second signals. 
   
     
     
         2 . The position detection apparatus according to  claim 1 , wherein
 the signal output unit does not output the first signal in a time period in which the plurality of second signals are output.   
     
     
         3 . The position detection apparatus according to  claim 1 , wherein
 the signal output unit includes
 a plurality of reflection pattern arrays fixed to one of the fixed member or the movable member and having different periods from each other, 
 a light source fixed to the other of the fixed member or the movable member, and 
 a plurality of light receivers fixed to the other of the fixed member or the movable member to which the light source is fixed and each receiving light emitted from the light source and reflected on the plurality of reflection pattern arrays. 
   
     
     
         4 . The position detection apparatus according to  claim 1 , wherein
 the second signal includes a signal that monotonously increases or monotonously decreases with respect to the position of the movable member.   
     
     
         5 . The position detection apparatus according to  claim 1 , further comprising:
 a phase counter that counts a phase change of the first signal, wherein   the position deriver derives a relative position based on a count value obtained by the phase counter.   
     
     
         6 . The position detection apparatus according to  claim 1 , further comprising:
 a switcher that outputs, to the signal output unit, a signal designating a displacement signal to be output to the signal output unit among the plurality of displacement signals.   
     
     
         7 . The position detection apparatus according to  claim 1 , wherein
 in deriving the relative position, based on the second signals output a plurality of times, the position deriver derives a displacement amount in a time in which the signal output unit outputs the first signal, the plurality of second signals, and the first signal in this order, and based on the first signal and the displacement amount, the position deriver derives a relative position.   
     
     
         8 . A lens apparatus comprising:
 a movable optical member; and   a position detection apparatus for detecting a position of a movable member relative to a fixed member, the position detection apparatus comprising:
 a signal output unit that outputs a plurality of displacement signals including a first signal that changes in a first period and a second signal that changes in a period longer than the first period, while switching among the plurality of displacement signals, in accordance with a change in the position of the movable member relative to the fixed member; and 
 a position deriver that derives an absolute position as the position of the movable member relative to the fixed member based on the plurality of displacement signals output from the signal output unit, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the movable member relative to the fixed member, wherein 
   in deriving the absolute position,
 the signal output unit outputs the first signal, a plurality of the second signals, and the first signal in this order, and 
 the position deriver derives the absolute position based on the plurality of displacement signals, 
   in deriving the relative position,
 the position deriver derives the relative position based on the first signal and the plurality of the second signals. 
   
     
     
         9 . An image pickup apparatus comprising:
 a lens apparatus comprising:
 a movable optical member; and 
 a position detection apparatus for detecting a position of a movable member relative to a fixed member, the position detection apparatus comprising:
 a signal output unit that outputs a plurality of displacement signals including a first signal that changes in a first period and a second signal that changes in a period longer than the first period, while switching among the plurality of displacement signals, in accordance with a change in the position of the movable member relative to the fixed member; and 
 a position deriver that derives an absolute position as the position of the movable member relative to the fixed member based on the plurality of displacement signals output from the signal output unit, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the movable member relative to the fixed member, wherein 
 
 in deriving the absolute position,
 the signal output unit outputs the first signal, a plurality of the second signals, and the first signal in this order, and 
 
 the position deriver derives the absolute position based on the plurality of displacement signals, 
   in deriving the relative position,
 the position deriver derives the relative position based on the first signal and the plurality of the second signals; and 
   an image pickup element that receives light from the lens apparatus.   
     
     
         10 . A lens command apparatus for driving and operating a lens apparatus including a movable optical member, the lens command apparatus comprising
 a position detection apparatus for detecting a position of a movable member relative to a fixed member, the position detection apparatus comprising:
 a signal output unit that outputs a plurality of displacement signals including a first signal that changes in a first period and a second signal that changes in a period longer than the first period, while switching among the plurality of displacement signals, in accordance with a change in the position of the movable member relative to the fixed member; and 
 a position deriver that derives an absolute position as the position of the movable member relative to the fixed member based on the plurality of displacement signals output from the signal output unit, and derives a relative position as a displacement amount with respect to a predetermined absolute position of the movable member relative to the fixed member, wherein 
   in deriving the absolute position,
 the signal output unit outputs the first signal, a plurality of the second signals, and the first signal in this order, and 
 the position deriver derives the absolute position based on the plurality of displacement signals, 
   in deriving the relative position,
 the position deriver derives the relative position based on the first signal and the plurality of the second signals.