Liquid transport device and liquid transport method

Abstract

A liquid transport device includes a drive mechanism having a rotor rotating when transporting a liquid, and a detection section adapted to detect a rotational angle of the rotor, and power of the detection section is switched between an ON state and an OFF state in sync with switching between drive and halt of the drive mechanism. Such a liquid transport device driven by the rotation of a cam or the rotor can reduce the power consumption of an encoder.

What is claimed is: 
     
         1 . A liquid transport device, comprising:
 a drive mechanism having a rotor rotating when transporting a liquid; and   a detection section adapted to detect a rotational angle of the rotor,   wherein power of the detection section is switched between an ON state and an OFF state in sync with switching between drive and halt of the drive mechanism.   
     
     
         2 . The liquid transport device according to  claim 1 , wherein
 the detection section includes a light emitting section adapted to emit light, and a light receiving section adapted to receive the light emitted, and   power of the light emitting section is switched between the ON state and the OFF state in sync with switching between the ON state and the OFF state of power of the drive mechanism.   
     
     
         3 . The liquid transport device according to  claim 2 , wherein
 the detection section has an encoder circuit adapted to output an output signal having a predetermined level based on a detection value of a rotational angle of the rotor, and   power of the encoder circuit is switched between the ON state and the OFF state in sync with the switching between the ON state and the OFF state of the power of the drive mechanism.   
     
     
         4 . The liquid transport device according to  claim 3 , wherein
 in starting drive of the drive mechanism, the power of the light emitting section is set to the ON state, and then the power of the encoder circuit is set to the ON state, and   in stopping drive of the drive mechanism, the power of the encoder circuit is set to the OFF state, and then the power of the light emitting section is set to the OFF state.   
     
     
         5 . The liquid transport device according to  claim 1 , wherein
 the detection section includes
 an encoder adapted to detect a rotational angle of the rotor, 
 a comparator circuit adapted to compare the detection value detected by the encoder and a predetermined reference value with each other to output a signal having one of an H level and an L level, and 
 a reference value setting section adapted to detect the signal output to vary the reference value. 
   
     
     
         6 . The liquid transport device according to  claim 5 , further comprising:
 a resetting section adapted to store a level of the signal output at a time point when the drive mechanism has stopped in a case of performing intermittent drive of repeating drive and halt of the drive mechanism, and apply a resetting voltage having a level corresponding to a level of the signal stored to the comparator circuit in driving the drive mechanism again.   
     
     
         7 . The liquid transport device according to  claim 6 , wherein
 the comparator circuit includes a comparator adapted to compare a level of an input voltage and a reference voltage with each other to output the signal having one of the H level and the L level, and   the resetting section applies the resetting voltage to a terminal of the comparator to which the input voltage is input.   
     
     
         8 . The liquid transport device according to  claim 6 , wherein
 the comparator circuit includes a comparator adapted to compare a level of an input voltage and a reference voltage with each other to output the signal having one of the H level and the L level, and   the resetting section applies the resetting voltage to a terminal of the comparator to which the reference voltage is input.   
     
     
         9 . The liquid transport device according to  claim 1 , wherein
 the detection section includes
 a first encoder adapted to detect the rotational angle of the rotor, 
 a second encoder adapted to detect the rotational angle of the rotor at a different position from a position of the first encoder, and 
 a control section adapted to determine a rotational direction of the rotor based on whether the level of the signal, which is output by the second encoder when the level of the signal output by the first encoder varies, is the H level or the L level. 
   
     
     
         10 . The liquid transport device according to  claim 1 , further comprising:
 a cam driven by the rotation of the rotor to thereby transport the liquid;   a rotation detection encoder adapted to detect a rotation reference position of at least one of the cam and the rotor;   a rotational angle detection encoder adapted to detect the rotational angle of the rotor; and   a control section adapted to detect a shift amount between the rotation reference position of at least one of the cam and the rotor detected by the rotation detection encoder, and the rotational angle of the rotor detected by the rotational angle detection encoder, and correct the rotation reference position as much as the shift amount detected.   
     
     
         11 . A liquid transport device, comprising:
 a drive mechanism having a rotor rotating when transporting a liquid;   an encoder adapted to detect a rotational angle of the rotor;   a comparator circuit adapted to compare the detection value detected by the encoder and a predetermined reference value with each other to output a signal having one of an H level and an L level; and   a reference value setting section adapted to detect the signal output to vary the reference value.   
     
     
         12 . The liquid transport device according to  claim 11 , wherein
 the drive mechanism includes a piezoelectric actuator adapted to make a vibrator element, which vibrates in accordance with a drive signal applied to the vibrator element, have contact with the rotor to rotate the rotor, and   the piezoelectric actuator is biased so that an end portion of the vibrator element and an outer circumferential portion of the rotor have contact with each other in a state in which a vibration orbit of the vibrator element and a rotational plane of the rotor are in parallel to each other.   
     
     
         13 . The liquid transport device according to  claim 11 , further comprising:
 a cam rotationally driven by the rotation of the rotor to thereby transport the liquid,   wherein the drive mechanism includes a reduction section adapted to reduce revolution of the rotor and then transmit the rotation of the rotor to the cam, and   the detection section detects a rotational angle of the reduction section.   
     
     
         14 . The liquid transport device according to  claim 11 , further comprising:
 a cam rotationally driven by the rotation of the rotor to transport the liquid,   wherein the drive mechanism includes a reduction section adapted to reduce revolution of the rotor and then transmit the rotation of the rotor to the cam, and   the detection section detects a rotational angle of the cam.   
     
     
         15 . The liquid transport device according to  claim 11 , further comprising:
 a resetting section adapted to store a level of the signal output at a time point when the drive mechanism has stopped in a case of performing intermittent drive of repeating drive and halt of the drive mechanism, and apply a resetting voltage having a level corresponding to a level of the signal stored to a predetermined terminal of the comparator circuit in driving the drive mechanism again.   
     
     
         16 . A liquid transport method, comprising:
 detecting a rotational angle of a rotor rotating when transporting a liquid; and   switching a power of a detection section adapted to detect the rotational angle of the rotor between an ON state and an OFF state in sync with switching between drive and halt of a drive mechanism having the rotor.   
     
     
         17 . The liquid transport method according to  claim 16 , further comprising:
 comparing a detection value detected and a predetermined reference value with each other to output a signal having one of an H level and an L level; and   detecting the signal output to vary the reference value.