US-20260125232-A1 - MEDIUM TRANSPORT DEVICE AND IMAGE READING DEVICE

US20260125232A1US 20260125232 A1US20260125232 A1US 20260125232A1US-20260125232-A1

Abstract

A medium transport device includes: a feeding roller that feeds a medium mounted on a medium mounting section; a separation roller that nips the medium with the feeding roller to separate the medium and is configured to rotate in a first rotation direction in which the medium is transported downstream and a second rotation direction that is opposite to the first rotation direction; a pressing member that presses the separation roller against the feeding roller; a pressing force change portion that changes a pressing force of the pressing member; and a single drive source that generates a driving force for the separation roller and a driving force for the pressing force change portion.

Inventors

Masaki Namiki
Kendai KAWAKAMI

Assignees

SEIKO EPSON CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251218
Priority Date: 20230210

Claims (9)

1 . A medium transport device comprising: a feeding roller that feeds a medium mounted on a medium mounting section; a separation roller that nips the medium with the feeding roller to separate the medium and is configured to rotate in a first rotation direction in which the medium is transported downstream in a transport direction and a second rotation direction that is opposite to the first rotation direction; a pressing member that generates a pressing force for pressing the separation roller against the feeding roller; a pressing force change portion that changes the pressing force of the pressing member; a single drive source that generates a driving force for the separation roller and a driving force for the pressing force change portion; and a control unit that receives information regarding the medium from a user, wherein the control unit drives the pressing force change portion to change the pressing force of the pressing member based on the information regarding the medium.
2 . The medium transport device according to claim 1 , wherein the pressing force change portion includes a pressing portion that presses the pressing member, and changes a pressing load with which the pressing portion presses the pressing member to change the pressing force of the pressing member.
3 . The medium transport device according to claim 2 , wherein the pressing force change portion includes an elongated body that includes the pressing portion and is configured to rotate around an axis, a power transmitted gear which is fixed to the elongated body and to which power of the drive source is transmitted, and a base portion that holds a base end of the pressing member and is configured to be displaced in a direction of the pressing force, and the base portion changes the pressing load by being displaced by a torque of the drive source transmitted via the power transmitted gear, the elongated body, and the pressing portion.
4 . The medium transport device according to claim 1 , wherein a one-way clutch is provided on a transmission path through which the driving force is transmitted from the drive source to the pressing force change portion, and the drive source transmits, via the one-way clutch, the driving force for rotating the separation roller in the second rotation direction when rotating forward, and transmits the driving force for changing the pressing force to the pressing force change portion when rotating in reverse.
5 . The medium transport device according to claim 4 , wherein the separation roller is configured to perform switching between a driving force transmission state in which the driving force is transmitted from the drive source, and a driving force non-transmission state in which the driving force is not transmitted, and the driving force transmission state of the separation roller is switched to the driving force non-transmission state when the drive source rotates in reverse.
6 . The medium transport device according to claim 1 , further comprising: a thickness detection unit that detects a thickness of the medium; and a control unit, wherein the control unit drives the pressing force change portion to change the pressing force of the pressing member based on a detection result of the thickness detection unit.
7 . The medium transport device according to claim 6 , wherein the thickness detection unit is provided downstream of the feeding roller in the transport direction, and the control unit causes the feeding roller to feed the medium to transport the medium to a detection position where the thickness of the medium is detectable by the thickness detection unit, and causes the thickness detection unit to detect the thickness of the medium in a state in which the medium is stopped at the detection position.
8 . The medium transport device according to claim 1 , further comprising a control unit that drives the pressing force change portion to change the pressing force of the pressing member, wherein the control unit changes the pressing force of the pressing member and changes a rotation speed of the separation roller.
9 . An image reading device comprising: the medium transport device according to claim 1 ; and a reading portion that reads an image on the medium.

Description

The present application is a continuation of US Patent Application Number 18/435,462 which is based on, and claims priority from JP Application Serial Number 2023-018870, filed February 10, 2023, the disclosures of which are hereby incorporated by reference herein in their entirety. BACKGROUND 1. Technical Field The present disclosure relates to a medium transport device and an image reading device. 2. Related Art JP-A-2019-116383 describes an example of these types of devices. JP-A-2019-116383 discloses that each of a first drive source 25 that drives a separation roller 15 and a load change unit 120 is provided with the intention of achieving suitable separation of various types of media from thin paper to thick paper with the separation roller. The load change unit 120 changes a pressing load of the separation roller 15 on a feeding roller 14 by switching a switching gear 125 between a first position M1 and a second position M2 (Paragraph 0129). However, in JP-A-2019-116383, there is room for improvement in the drive source that drives the separation roller and a portion of the drive source that changes the pressing load of the separation roller on the feeding roller 14 in terms of promoting device size reduction. SUMMARY According to an aspect of the present disclosure, a medium transport device includes: a feeding roller that feeds a medium mounted on a medium mounting section; a separation roller that nips the medium with the feeding roller to separate the medium and is configured to rotate in a first rotation direction in which the medium is transported downstream and a second rotation direction that is opposite to the first rotation direction; a pressing member that presses the separation roller against the feeding roller; a pressing force change portion that changes a pressing force of the pressing member; and a single drive source that generates a driving force for the separation roller and a driving force for the pressing force change portion. According to an aspect of the present disclosure, an image reading device includes: the medium transport device according to the above-described aspect; and a reading portion that reads an image on the medium. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an internal configuration of an image reading device according to a first embodiment. FIG. 2 is a plan view illustrating a main part of a power transmission path according to the first embodiment. FIG. 3 is a perspective view illustrating the main part of the power transmission path according to the first embodiment. FIG. 4 is a perspective view illustrating the main part of the power transmission path according to the first embodiment when viewed in a different direction. FIG. 5 is a side cross-sectional view illustrating the main part of the power transmission path according to the first embodiment. FIG. 6 is a perspective view illustrating a pressing force change portion according to the first embodiment. FIG. 7 is a perspective view illustrating a main part of the pressing force change portion according to the first embodiment. FIGS. 8A to 8C are views for describing an operation of the pressing force change portion according to the first embodiment. FIGS. 9A and 9B are perspective views illustrating a main part of a sensor portion that senses a position of a cam according to the first embodiment. FIG. 10 is a flowchart for describing automation of switching of a medium separation mode according to the first embodiment. DESCRIPTION OF EMBODIMENTS Hereinafter, the present disclosure will be schematically described first. According to a first aspect of the present disclosure, a medium transport device includes: a feeding roller that feeds a medium mounted on a medium mounting section; a separation roller that nips the medium with the feeding roller to separate the medium and is configured to rotate in a first rotation direction in which the medium is transported downstream and a second rotation direction that is opposite to the first rotation direction; a pressing member that presses the separation roller against the feeding roller; a pressing force change portion that changes a pressing force of the pressing member; and a single drive source that generates a driving force for the separation roller and a driving force for the pressing force change portion. Here, the "driving force for the separation roller" in "a single drive source that generates a driving force for the separation roller and a driving force for the pressing force change portion" means power for rotating the separation roller, and the "driving force for the pressing force change portion" means power for operating the pressing force change portion to change the pressing force of the pressing member. According to this aspect, the pressing member that presses the separation roller against the feeding roller, the pressing force change portion that changes the pressing force of the pressing member, and the single drive so