Sheet conveyance apparatus that detects overlapping of plurality of sheets, and image reading apparatus

Patent metadata

Field	Value
Publication number	US-9981819-B2
Application number	US-201615228110-A
Country	US
Kind code	B2
Filing date	Aug 4, 2016
Priority date	Aug 27, 2015
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A transmitter transmits ultrasound to the conveyance path. A receiver receives the ultrasound. A double-feed detector detects whether or not double-feed of a plurality of sheets has occurred. A controller causes the transmitter to transmit ultrasound at a first burst interval when determining the threshold value, and causes the transmitter to transmit ultrasound at a second burst interval, which is shorter than the first burst interval, when detecting the double-feed of sheets. A double-feed detector determines a threshold value that enables distinction between double-feed and single-feed.

First claim

What is claimed is:

1. A sheet conveyance apparatus comprising:
a conveyance unit configured to convey a sheet on a conveyance path;
a transmitter configured to transmit ultrasound to the conveyance path based on a burst wave;
a receiver configured to receive the ultrasound transmitted from the transmitter, the receiver being mounted opposing the transmitter;
a double-feed detector configured to detect whether or not double-feed of a plurality of sheets has occurred on the conveyance path by comparing, with a threshold value, an amplitude level of an output signal that is output from the receiver; and
an ultrasound controller configured to control generation of a plurality of burst waves so that in a process for determining the threshold value a plurality of burst waves are generated at a first interval to transmit a plurality of ultrasound from the transmitter, and in a process for detecting a double-feed of a plurality of sheets a plurality of burst waves are generated at a second interval shorter than the first interval to transmit a plurality of ultrasound from the transmitter;
wherein the double-feed detector determines the threshold value that enables distinction between double-feed and single-feed, based on an amplitude level of an output signal that has been output by the receiver receiving the ultrasound transmitted by the transmitter based on a plurality of burst waves generated at the first interval in a state where no sheet exists on the conveyance path.

2. The sheet conveyance apparatus according to claim 1 ,
wherein the transmitter and the receiver are mounted relative to the conveyance path.

3. The sheet conveyance apparatus according to claim 1 ,
wherein the first interval is a time required for an echo of the ultrasound transmitted from the transmitter to become smaller than or equal to a predetermined tolerance limit.

4. The sheet conveyance apparatus according to claim 1 ,
wherein the second interval is a time required for an echo of the ultrasound transmitted from the transmitter to become smaller than or equal to a predetermined tolerance limit.

5. The sheet conveyance apparatus according to claim 1 ,
wherein the double-feed detector determines the threshold value by multiplying the amplitude level obtained in a state where no sheet exists on the conveyance path by a correction coefficient.

6. The sheet conveyance apparatus according to claim 1 ,
wherein the double-feed detector determines the threshold value by multiplying the amplitude level obtained in a state where no sheet exists on the conveyance path by a correction coefficient and a margin.

7. A sheet conveyance apparatus comprising:
a conveyance unit configured to convey a sheet on a conveyance path;
a transmitter configured to transmit ultrasound to the conveyance path;
a receiver configured to receive the ultrasound transmitted from the transmitter, the receiver being mounted opposing the transmitted;
a double-feed detector configured to detect whether or not double-feed of a plurality of sheets has occurred on the conveyance path by comparing, with a threshold value, an amplitude level of an output signal that is output from the receiver; and
an ultrasound controller configured to cause the transmitter to transmit ultrasound at a first burst interval when determining the threshold value, and cause the transmitter to transmit ultrasound at a second burst interval, which is shorter than the first burst interval, when detecting the double-feed of sheets,
wherein the double-feed detector determines the threshold value that enables distinction between double-feed and single-feed, based on an amplitude level of an output signal that has been output by the receiver receiving the ultrasound transmitted at the first burst interval by the transmitter in a state where no sheet exists on the conveyance path,
wherein the ultrasound controller causes the transmitter to transmit ultrasound in a state where no sheet exists on the conveyance path from a time when an instruction to convey a sheet is given until the sheet reaches a space between the transmitter and the receiver, and causes the double-feed detector to determine the threshold value, and
upon the sheet reaching the space between the transmitter and the receiver, the double-feed detector detects whether or not double-feed of a plurality of sheets has occurred, using the threshold value.

8. A sheet conveyance apparatus comprising:
a conveyance unit configured to convey a sheet on a conveyance path;
a transmitter configured to transmit ultrasound to the conveyance path;
a receiver configured to receive the ultrasound transmitted from the transmitter, the receiver being mounted opposing the transmitter;
a double-feed detector configured to detect whether or not double-feed of a plurality of sheets has occurred on the conveyance path by comparing, with a threshold value, an amplitude level of an output signal that is output from the receiver; and
an ultrasound controller configured to cause the transmitter to transmit ultrasound at a first burst interval when determining the threshold value, and cause the transmitter to transmit ultrasound at a second burst interval, which is shorter than the first burst interval, when detecting the double-feed of sheets,
wherein the double-feed detector determines the threshold value that enables distinction between double-feed and single-feed, based on an amplitude level of an output signal that has been output by the receiver receiving the ultrasound transmitted at the first burst interval by the transmitter in a state where no sheet exists on the conveyance path,
wherein the receiver includes:
a receiving element configured to output an output signal corresponding to an amplitude of the ultrasound received;
an amplifier configured to amplify the output signal that has been output from the receiving element; and
a convertor configured to perform analog-digital conversion on the output signal that has been amplified by the amplifier,
wherein the amplifier amplifies the output signal from the receiving element with a first degree of amplification in a case where the threshold value is determined, and amplifies the output signal from the receiving element with a second degree of amplification, which is larger than the first degree of amplification, in a case where it is detected whether or not double-feed of a plurality of sheets has occurred.

9. The sheet conveyance apparatus according to claim 8 ,
wherein the amplifier has a first amplification stage, and a second amplification stage connected to the first amplification stage as a subsequent stage of the first amplification stage,
wherein the convertor has a first conversion circuit configured to perform analog-digital conversion on the output signal that has been amplified at the first amplification stage, and a second conversion circuit configured to perform analog-digital conversion on the output signal that has been amplified at the first amplification stage and also amplified at the second amplification stage,
wherein the double-feed detector determines the threshold value using the amplitude level of the output signal that has been output by the first conversion circuit, and wherein the double-feed detector detects whether or not double-feed of a plurality of sheets has occurred, using the amplitude level of the output signal that has been output by the second conversion circuit.

10. An image reading apparatus comprising:
a conveyance unit configured to convey a sheet on a conveyance path;
a transmitter configured to transmit ultrasound to the conveyance path based on a burst wave;
a receiver configured to receive the ultrasound transmitted from the transmitt

Assignees

• Canon Kk

Inventors

• Arima Makoto
• Tomii Taishi

Classifications

• B65H2801/06

  Office-type machines, e.g. photocopiers · CPC title

• B65H2557/63

  Optimisation, self-adjustment, self-learning processes or procedures, e.g. during start-up · CPC title

• B65H5/062

  between rollers or balls · CPC title

• G01N2291/048

  Transmission, i.e. analysed material between transmitter and receiver · CPC title

• G01N2291/0237

  Thin materials, e.g. paper, membranes, thin films · CPC title