Medium conveyance apparatus with a plurality of sound wave sensors driven by single drive signal and outputting sound wave signals at different timings

Abstract

A medium conveyance apparatus includes a drive signal output circuit to output a drive signal at a predetermined timing, a first sound wave emitter to output a sound wave based on the drive signal outputted at the predetermined timing, a first sound wave receiver to output a first sound wave signal corresponding to the received sound wave, a second sound wave emitter to output a sound wave based on the drive signal outputted at the predetermined timing, a second sound wave receiver to output a second sound wave signal corresponding to the received sound wave, a processor to determine a state of the medium based on the first sound wave signal and the second sound wave signal, and an output circuit to output the first sound wave signal and the second sound wave signal to the processor at timings different from each other.

What is claimed is: 
     
         1 . A medium conveyance apparatus comprising:
 a conveying roller to convey a medium along a conveyance path;   a drive signal output circuit to output a drive signal at a predetermined timing;   a first sound wave emitter to output a sound wave including at least an audible sound or ultrasonic wave based on the drive signal outputted at the predetermined timing;   a first sound wave receiver located to face the first sound wave emitter with the conveyance path in between to output a first sound wave signal corresponding to a received sound wave;   a second sound wave emitter to output a sound wave including at least an audible sound or ultrasonic wave based on the drive signal outputted at the predetermined timing;   a second sound wave receiver located to face the second sound wave emitter with the conveyance path in between to output a second sound wave signal corresponding to a received sound wave;   a processor to determine a state of the medium based on the first sound wave signal and the second sound wave signal; and   an output circuit to output the first sound wave signal and the second sound wave signal to the processor at timings different from each other.   
     
     
         2 . The medium conveyance apparatus according to  claim 1 , wherein a distance between the first sound wave emitter and the first sound wave receiver differs from a distance between the second sound wave emitter and the second sound wave receiver such that the output circuit outputs the first sound wave signal and the second sound wave signal to the processor at timings different from each other. 
     
     
         3 . The medium conveyance apparatus according to  claim 1 , wherein a signal delay circuit is provided between the drive signal output circuit and the first sound wave emitter or the second sound wave emitter, or between the first sound wave receiver or the second sound wave receiver and the output circuit such that the output circuit outputs the first sound wave signal and the second sound wave signal to the processor at timings different from each other. 
     
     
         4 . The medium conveyance apparatus according to  claim 1 , further comprising one amplifier to amplify the drive signal outputted from the drive signal output circuit and output to the first sound wave emitter and the second sound wave emitter. 
     
     
         5 . The medium conveyance apparatus according to  claim 1 , further comprising:
 a first amplifier to amplify the drive signal outputted from the drive signal output circuit and output to the first sound wave emitter; and   a second amplifier to amplify the drive signal outputted from the drive signal output circuit and output to the second sound wave emitter.   
     
     
         6 . The medium conveyance apparatus according to  claim 1 , further comprising one amplifier to amplify the first sound wave signal and the second sound wave signal outputted from the output circuit and output to the processor. 
     
     
         7 . The medium conveyance apparatus according to  claim 1 , further comprising:
 a first amplifier to amplify the first sound wave signal outputted from the first sound wave receiver and output to the output circuit; and   a second amplifier to amplify the second sound wave signal outputted from the second sound wave receiver and output to the output circuit.   
     
     
         8 . A medium conveyance method comprising:
 determining a state of a medium based on a first sound wave signal outputted according to a received sound wave by a first sound wave receiver located to face a first sound wave emitter with a conveyance path in between, wherein the first sound wave emitter outputs a sound wave including at least an audible sound or ultrasonic wave based on a drive signal outputted at a predetermined timing by a drive signal output circuit, and a second sound wave signal outputted according to a received sound wave by a second sound wave receiver located to face a second sound wave emitter with the conveyance path in between, wherein the second sound wave emitter outputs a sound wave including at least an audible sound or ultrasonic wave based on the drive signal outputted at the predetermined timing by the drive signal output circuit, wherein   the first sound wave signal and the second sound wave signal are outputted at timings different from each other by an output circuit.   
     
     
         9 . The method according to  claim 8 , wherein a distance between the first sound wave emitter and the first sound wave receiver differs from a distance between the second sound wave emitter and the second sound wave receiver such that the first sound wave signal and the second sound wave signal are outputted by the output circuit at timings different from each other. 
     
     
         10 . The method according to  claim 8 , wherein a signal delay circuit is provided between the drive signal output circuit and the first sound wave emitter or the second sound wave emitter, or between the first sound wave receiver or the second sound wave receiver and the output circuit such that the first sound wave signal and the second sound wave signal are outputted by the output circuit at timings different from each other. 
     
     
         11 . The method according to  claim 8 , wherein the drive signal outputted from the drive signal output circuit is amplified by one amplifier and outputted to the first sound wave emitter and the second sound wave emitter. 
     
     
         12 . The method according to  claim 8 , wherein
 the drive signal outputted from the drive signal output circuit is amplified by a first amplifier and outputted to the first sound wave emitter, and wherein   the drive signal outputted from the drive signal output circuit is amplified by a second amplifier and outputted to the second sound wave emitter.   
     
     
         13 . The method according to  claim 8 , wherein the first sound wave signal and the second sound wave signal outputted from the output circuit are amplified and outputted by one amplifier. 
     
     
         14 . The method according to  claim 8 , wherein
 the first sound wave signal outputted from the first sound wave receiver is amplified by a first amplifier and outputted to the output circuit, and   the second sound wave signal outputted from the second sound wave receiver is amplified by a second amplifier and outputted to the output circuit.   
     
     
         15 . A computer-readable, non-transitory medium storing executable instructions for conveying a medium, the executable instructions comprising:
 determining a state of a medium based on a first sound wave signal outputted according to a received sound wave by a first sound wave receiver located to face a first sound wave emitter with a conveyance path in between, wherein the first sound wave emitter outputs a sound wave including at least an audible sound or ultrasonic wave based on a drive signal outputted at a predetermined timing by a drive signal output circuit, and a second sound wave signal outputted according to a received sound wave by a second sound wave receiver located to face a second sound wave emitter with the conveyance path in between, wherein the second sound wave emitter outputs a sound wave including at least an audible sound or ultrasonic wave based on the drive signal outputted at the predetermined timing by the drive signal output circuit, wherein   the first sound wave signal and the second sound wave signal are outputted at timings different from each other by an output circuit.   
     
     
         16 . The computer-readable, non-transitory medium according to  claim 15 , wherein a distance between the first sound wave emitter and the first sound wave receiver differs from a distance between the second sound wave emitter and the second sound wave receiver such that the first sound wave signal and the second sound wave signal are outputted by the output circuit at timings different from each other. 
     
     
         17 . The computer-readable, non-transitory medium according to  claim 15 , wherein a signal delay circuit is provided between the drive signal output circuit and the first sound wave emitter or the second sound wave emitter, or between the first sound wave receiver or the second sound wave receiver and the output circuit such that the first sound wave signal and the second sound wave signal are outputted by the output circuit at timings different from each other. 
     
     
         18 . The computer-readable, non-transitory medium according to  claim 15 , wherein the drive signal outputted from the drive signal output circuit is amplified by one amplifier and outputted to the first sound wave emitter and the second sound wave emitter. 
     
     
         19 . The computer-readable, non-transitory medium according to  claim 15 , wherein
 the drive signal outputted from the drive signal output circuit is amplified by a first amplifier and outputted to the first sound wave emitter, and   the drive signal outputted from the drive signal output circuit is amplified by a second amplifier and outputted to the second sound wave emitter.   
     
     
         20 . The computer-readable, non-transitory medium according to  claim 15 , wherein the first sound wave signal and the second sound wave signal outputted from the output circuit are amplified and outputted by one amplifier.