SHEET TRANSPORTING DEVICE, IMAGE READING DEVICE, AND IMAGE FORMING APPARATUS

Abstract

A sheet transporting device includes: a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction; a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present. The second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2023-044892 filed Mar. 22, 2023.

BACKGROUND

(i) Technical Field

The present disclosure relates to a sheet transporting device, an image reading device, and an image forming apparatus.

(ii) Related Art

Examples of existing technologies relating to a sheet transporting device that transports sheets such as documents are disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2010-058899, Japanese Patent No. 7083449, and Japanese Unexamined Patent Application Publication No. 2014-118282.

Japanese Unexamined Patent Application Publication No. 2010-058899 discloses a device including an optical sensor located above a document placed on a document tray and including a light emitting device and a light receiving device to detect a trailing end of the document transported from the document tray.

Japanese Patent No. 7083449 discloses a device including a first detector, a second detector, and an estimator. The first detector detects the presence of a sheet placed on a sheet receiving tray capable of receiving sheets. The second detector detects the presence of a sheet located upstream from the first detector in a sheet transport direction. Before and after a start of transporting the sheet, the estimator estimates the sheet size of a sheet based on a detection result from the second detector when the detection result from the second detector changes from a no-sheet state within a predetermined period, and estimates the sheet size of the sheet based on the detection result from the first detector when the detection result from the second detector has no change from the no-sheet state within the predetermined period.

Japanese Unexamined Patent Application Publication No. 2014-118282 discloses an automatic document transport device including a document table that receives a document, multiple document length detectors that detect the length of the document placed on the document table, a final document detector disposed downstream from the document length detectors in a document transport direction to detect a final document on the document table, a document set detector disposed downstream from the final document detector in the document transport direction to detect the document placed on the document table, a transport controller that performs transport control for controlling timing of transporting a document to a document read position based on a signal from the document set detector, and a document length determiner that determines the length of the set document based on the signals from the document length detectors. The document length determiner determines the length of the document based on final information from the final document detector when the document length detectors fail to detect the length.

SUMMARY

Aspects of non-limiting embodiments of the present disclosure relate to a device capable of detecting the sheet size smaller than or equal to a predetermined length in a transport direction without increasing the number of detectors disposed at a sheet receiver compared to a structure additionally including a final document detector that detects a final document on the sheet receiver.

Aspects of certain non-limiting embodiments of the present disclosure address the features discussed above and/or other features not described above. However, aspects of the non-limiting embodiments are not required to address the above features, and aspects of the non-limiting embodiments of the present disclosure may not address features described above.

According to an aspect of the present disclosure, there is provided a sheet transporting device that includes: a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction; a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present, wherein the second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein:

FIG. 1 is an entire structure diagram of an image forming apparatus according to a first exemplary embodiment of the present disclosure;

FIG. 2 is a structure diagram of an image reading device according to the first exemplary embodiment of the present disclosure;

FIG. 3 is a plan view of a structure of a platen glass;

FIG. 4 is a perspective view the image reading device according to the first exemplary embodiment of the present disclosure;

FIG. 5 is a plan structure diagram of a related portion of the image reading device according to the first exemplary embodiment of the present disclosure;

FIG. 6 is a table for determining the document size;

FIG. 7 is a block diagram of a control device of the image reading device according to the first exemplary embodiment of the present disclosure; and

FIG. 8 is a cross-sectional view of a structure of the image reading device according to the first exemplary embodiment of the present disclosure in the state of reading a document.

DETAILED DESCRIPTION

Exemplary embodiments of the present disclosure are described below with reference to the drawings.

First Exemplary Embodiment

FIG. 1 is a schematic diagram of the entirety of an image forming apparatus including a sheet transporting device and an image reading device according to a first exemplary embodiment of the present disclosure.

Entire Structure of Image Forming Apparatus

An image forming apparatus according to the first exemplary embodiment is a full-color image forming apparatus that, for example, reads an image on the document with an image reading device, appropriately performs predetermined image processing on image information of the document read by the image reading device, forms a full-color or monochrome image on a recording medium, and prints a full-color or monochrome image on the recording medium based on image information transmitted from an external device.

As illustrated in FIG. 1, an image forming apparatus 1 roughly includes an apparatus body 2 formed in a substantially rectangular parallelepiped box extending in the vertical direction, an image reading device 3 disposed over the apparatus body 2, a single or multiple sheet containers 5 disposed in the apparatus body 2 to accommodate recording sheets 4 serving as an example of recording media, sheet feeders 6 that separately feed the recording sheets 4 accommodated in the sheet containers 5 one by one, a sheet transporter 7 that transports the recording sheets 4 fed by the sheet feeders 6 along a predetermined transport path, an image forming portion 8 serving as an example of an image forming member that forms full-color or monochrome images on the recording sheets 4 transported by the sheet transporter 7, and single or multiple sheet discharging portions 9 to which the recording sheets 4 on which the images are formed by the image forming portion 8 are discharged. The sheet transporter 7 turns upside down a recording sheet 4 on which an image is formed on a first surface (a top surface) with a double-side transporter 7a, and transports the recording sheet 4 to the image forming portion 8 again to form full-color or monochrome images on both surfaces of the recording sheet 4.

The image forming portion 8 may have any structure capable of forming full-color or monochrome images on the recording sheets 4. Examples of such a structure include a device that forms full-color or monochrome images on recording sheets 4 with electrophotography using toner of four colors including yellow (Y), magenta (M), cyan (C), and black (K), and a device that forms full-color or monochrome images on the recording sheets 4 with inkjet recording.

Structure of Image Reading Device

The image reading device 3 according to the first exemplary embodiment functions as a duplex automatic document feeder (DADF) capable of automatically reading both surfaces of a document. As described above, for example, the image reading device 3 is located over the apparatus body 2 of the image forming apparatus 1. The image reading device 3 may naturally be located alone separately from the image forming apparatus 1, or combined with another electronic device such as an image processing device that performs another graphic processing.

As illustrated in FIG. 2, the image reading device 3 roughly includes an image reading device body 13 and an automatic document transport device 14. The image reading device body 13 reads an image on a document 12 placed on a platen glass 11. The automatic document transport device 14 is an example of a sheet transporting device that is attached to be openable or closeable about a rotation shaft not illustrated located above the image reading device body 13 and at a far side in the drawing. The automatic document transport device 14 has a function as a document holding member (a platen cover) that holds the document 12 placed on the platen glass 11 and automatically transports documents 25 to a read position of the platen glass 11. As described below, not only the function of automatically transporting the documents 25 to the read position of the platen glass 11, the automatic document transport device 14 also functions as a second image reader that reads an image on the other surface (back surface) of each document 25 automatically transported.

The image reading device body 13 is formed in a rectangular parallelepiped box having an upper end surface substantially fully open except at the outer peripheral portion and one end portion (left end portion in the drawing) in the width direction. The opening in the upper end surface of the image reading device body 13 receives the platen glass 11 that receives the document 12. As illustrated in FIG. 3, the platen glass 11 has so-called a side registration mechanism to position the document 12 while allowing edges 12a and 12b of the document 12 to abut against one end portion 11a (the upper end portion in the drawing) in a direction of reading the document 12 (main scanning direction) and a front end portion 11b (the left end portion in the drawing) in a direction crossing the direction of reading the document 12 (sub-scanning direction). The document 12 that is pressed by the automatic document transport device 14 while having a to-be-read surface facing down to have its image read is positioned on the platen glass 11. As illustrated in FIG. 2, the automatic document transport device 14 also functioning as a document holding member includes, at its lower end portion, an elastic layer 15 that presses the document 12 against the platen glass 11 and that has a white lower end surface that faces the platen glass 11.

As illustrated in FIG. 2, the image reading device body 13 accommodates a light source 16 formed from, for example, a light emitting diode (LED) or a halogen lamp that irradiates an image on the document 12 placed on the platen glass 11, a full-rate mirror 17 that reflects a reflection light image reflected from the document 12 toward reading elements 21, two half-rate mirrors 18 and 19 that reflect the reflection light image from the document 12 reflected by the full-rate mirror 17 toward the reading elements 21, an imaging lens 20 that forms, on the reading elements 21, a reflection light image from the document 12 reflected by the half-rate mirrors 18 and 19 at predetermined magnifying power, and the reading elements 21 each formed from a charge-coupled device (CCD) that reads the reflection light image from the document 12 in full color or monochrome. The light source 16, the full-rate mirror 17, the two half-rate mirrors 18 and 19, the imaging lens 20, and the reading elements 21 form a first image reading member.

To read an image on the document 12 placed on the platen glass 11, the image reading device 3 reads the entire image on the document 12 with the reading elements 21 in full color or monochrome at predetermined magnifying power by moving a first carriage 22 carrying the light source 16 and the full-rate mirror 17 and a second carriage 23 carrying the half-rate mirrors 18 and 19 in the sub-scanning direction at a predetermined speed.

The main scanning direction indicates a direction in which the reading elements 21 scan image information of the document 12 to read the image on the document 12, that is, a direction in which the reading elements 21 are arranged. The sub-scanning direction indicates a direction crossing the scanning direction, that is, a direction in which the light source 16, the full-rate mirror 17, and the half-rate mirrors 18 and 19 move.

As illustrated in FIG. 2 and FIG. 3, a first read portion 26 formed from a slit glass surface that reads an image on a first surface (the top surface) of the document 25 transported by the automatic document transport device 14 is disposed at a near end portion (the left end portion, in the drawings) in the sub-scanning direction of the platen glass 11. A document guide 27 having a substantially triangular cross section is disposed between the platen glass 11 and the first read portion 26. The end of the document 12 placed on the platen glass 11 is abutted against the document guide 27. The document guide 27 guides the document 25 that has passed the first read portion 26 downstream in the transport direction or obliquely upward. A side surface of the document guide 27 closer to the first read portion 26 is curved in a concave shape to smoothly guide the document 25 downstream in the transport direction. A guide roller 27a that guides the document 12 to the first read portion 26 is rotatably disposed upstream from the first read portion 26.

When reading an image on the document 25 transported by the automatic document transport device 14, the image reading device 3 reads the image on the document 25 with the reading elements 21 while the first carriage 22 carrying the light source 16 and the full-rate mirror 17 and the second carriage 23 carrying the half-rate mirrors 18 and 19 are stopped at the positions illustrated in FIG. 2 to irradiate, with light from the light source 16, the image on the top surface or one surface of the document 25 that passes the first read portion 26, by forming an reflection light image reflected by the full-rate mirror 17 and the half-rate mirrors 18 and 19 on the reading elements 21 via the imaging lens 20.

As illustrated in FIG. 2, the automatic document transport device 14 includes a document tray 28 (an example of a sheet receiver) that receives the document 25 serving as an example of a sheet, an automatic document feeder 29 that transports the document 25 received on the document tray 28 along a document transport path 40 past the first read portion 26, the first read portion 26 that reads an image on a first surface (the top surface) of the document 25 transported by the automatic document feeder 29, a second read portion 30 that includes a second image reading member that similarly reads an image on a second surface (the back surface) of the document 25 transported by the automatic document feeder 29, and a discharge tray 31 serving as an example of a sheet discharging member that receives the documents 25 having the images read by the first and second read portions 26 and 30 and sequentially discharged to be stacked on the discharge tray 31.

The second read portion 30 is formed from, for example, a contact image sensor (CIS) as an example of a second image reading member capable of reading the image on the back surface of the document 25 transported along the document transport path 40 at a position close to the image.

The automatic document transport device 14 according to the first exemplary embodiment includes the first read portion 26 that reads the image on the first surface (the top surface) of the document 25, and the second read portion 30 that reads the image on the second surface (the back surface) of the document 25, but the automatic document transport device 14 is not limited to this structure. Instead, the automatic document transport device 14 may simply include the first read portion 26 that reads the image on the first surface (the top surface) of the document 25, and may turn the document 25 upside down through a reverse transport path not illustrated disposed at part of the document transport path 40, and transport the turned document 25 again to the first read portion 26.

As illustrated in FIG. 2, the document tray 28 has a planar shape capable of receiving the document 25 in A3 (297 mm×420 mm) (in the longitudinal direction) at maximum by appropriately using an extension tray not illustrated drawable toward the trailing end in the transport direction of the document 25. For example, the document tray 28 has a size, with the length in the main scanning direction (the width direction) crossing the transport direction of the document 25, capable of receiving the document 25 in A4 (210 mm×297 mm) in the longitudinal direction. The document 25 is placed on the document tray 28 while having the to-be-read surface facing upward and while having the leading end in the transport direction abutting against and aligned with a stop plate 32 disposed at the document tray 28.

In the first exemplary embodiment, the document tray 28 simply includes a single first size sensor 101 as a detector for the sub-scanning direction that detects the size in the transport direction of the document 25 (the sub-scanning direction). The first size sensor 101 may be either an optical or mechanical sensor capable of detecting the size of the document 25.

The first size sensor 101 detects, for example, whether the length in the transport direction of the document 25 (the sub-scanning direction) is greater than or equal to a first length L1. The first length L1 is, for example, a value approximate to 297 mm or a dimension of the document 25 in A4 in the longitudinal direction, and a value slightly greater than 297 mm by ΔL (approximately 310 mm). Thus, the first size sensor 101 detects that, for example, the document 25 placed on the document tray 28 has a size of A3 or B4 greater than the length in the longitudinal direction of the document 25 in A4.

As illustrated in FIG. 4, the document tray 28 includes a pair of side guides 33 and 34 having both end portions in the main scanning direction (the width direction) crossing the transport direction of the document 25 abutting against and aligned with the document 25. Unlike the platen glass 11, the document tray 28 has a so-called center registration mechanism that receives the document 25 with reference to the center in the main scanning direction crossing the transport direction of the document 25. The side guides 33 and 34 are disposed on both sides of the document tray 28 in the main scanning direction. The left and right side guides 33 and 34 are moved (in an interlocking manner) to abut against both edges of the document 25 placed on the document tray 28 with reference to the center in the main scanning direction crossing the transport direction of the document 25. Thus, the document 25 placed on the document tray 28 is aligned with reference to the center in the main scanning direction crossing the transport direction while the left and right side guides 33 and 34 abut against both edges of the document 25.

As illustrated in FIG. 4 and FIG. 5, the side guides 33 and 34 include actuators 33a and 34a to detect the size in the main scanning direction crossing the transport direction of the document 25 in accordance with the positions of the side guides 33 and 34. Second to fifth size sensors 102 to 105 are attached to the document tray 28. The second to fifth size sensors 102 to 105 detect the size (width) of the document 25 in the main scanning direction crossing the transport direction in accordance with the positions of the actuators 33a and 34a of the side guides 33 and 34. The second to fifth size sensors 102 to 105 selectively detect the positions of the side guides 33 and 34 in the sub-scanning direction by detecting multiple openings, not illustrated, in the actuators 33a and 34a. The document tray to which the second to fifth size sensors 102 to 105 are attached is capable of detecting sixteen different sizes at maximum in the sub-scanning direction of the document 25 with ON/OFF combinations or outputs from the second to fifth size sensors 102 to 105.

As illustrated in FIG. 6, the first exemplary embodiment employs twelve ON/OFF combinations (groups) or outputs from the second to fifth size sensors 102 to 105, including “ON, OFF/ON, OFF, and ON”, “ON, OFF, OFF, and OFF”, “ON, OFF, ON, and OFF”, “ON, OFF. ON, and ON”, “ON, ON, ON, and ON”, “ON, ON, ON, and OFF”, “OFF, ON, ON, and OFF”, “OFF, ON, ON, and ON”, “OFF, OFF, ON, and ON”, “OFF, OFF, OFF, and ON”, “OFF, OFF, OFF, and OFF”, and “OFF, OFF, ON, and OFF”. Here, “ON, OFF/ON, OFF, ON” in the group 1 indicates that the output from the third size sensor 103 may be either OFF or ON.

The groups 1 to 12 or combinations of the outputs from the second to fifth size sensors 102 to 105 have specific detection widths. The group 1 detects the width within W1≥W≥W2, the group 2 detects the width within W2>W≥W3, the group 3 detects the width within W3>W≥W4, the group 4 detects the width within W4>W≥W5, the group 5 detects the width within W5>W≥W6, the group 6 detects the width within W6>W≥W7, the group 7 detects the width within W7>W≥W8, the group 8 detects the width within W8>W≥W9, the group 9 detects the width within W9>W≥W10, the group 10 detects the width within W10>W≥W11, the group 11 detects the width within W11>W≥W12, and the group 12 detects the width within W12>W≥W13.

As illustrated in FIG. 2, the automatic document feeder 29 includes the document transport path 40 as an example of a sheet transport path along which the document 25 placed on the document tray 28 is transported to the first and second read portions 26 and 30. A nudger roller 41 and a pair of separation rollers 42 are disposed at an upstream most end portion of the document transport path 40. The nudger roller 41 feeds the uppermost document 25 placed on the document tray 28. The pair of separation rollers 42 are disposed downstream from the nudger roller 41 in the transport direction of the document 25 to separate the documents 25 fed by the nudger roller 41 one from another.

The pair of separation rollers 42 include a feed roller 43 that transports the document 25 downstream, and a retard roller 44 that is pressed against the feed roller 43 to rotate in the direction opposite to the direction in which the feed roller 43 rotates or to be urged in the opposite direction.

Along the document transport path 40 of the automatic document transport device 14, multiple pairs of transport rollers 45 to 49 that transport the documents 25 separated by the pair of separation rollers 42 one from another while holding the documents 25, multiple guide members 50 to 55 that guide the top surfaces and the back surfaces of the documents 25 transported by the pairs of transport rollers 45 to 49, and a pair of discharge rollers 56 that discharge the documents 25 to the discharge tray 31 serving as a discharging member are disposed.

As illustrated in FIG. 2 and FIG. 5, a sheet pass sensor 107 is disposed downstream from the pair of separation rollers 42 in the document transport direction and upstream from the first pair of transport rollers 45 in the document transport direction, near a center portion in a direction crossing the transport direction of the document 25. The sheet pass sensor 107 serves as an example of a second detector that detects whether any document 25 is transported by the pair of separation rollers 42. As illustrated in FIG. 2, a jam sensor 108 that detects a transport error of the document 25 is disposed downstream of the pair of transport rollers 46 at the document transport path 40. A leading-end sensor 109 that detects the leading end of each document 25 and secures the storage area for storing data of the document 25 to be read by the reading elements 21 is disposed at the document transport path 40 downstream from the pair of transport rollers 47 and upstream from the guide roller 27a.

As illustrated in FIG. 2, the discharge tray 31 includes a planar alignment stopper 57 that stands at an upstream end portion in the direction of discharging the document 25 to allow the end of the document 25 to be abutted against and aligned with the alignment stopper 57. The discharge tray 31 includes a first inclined portion 58 located below the document tray 28 in the vertical direction and having a trailing end portion in the horizontal direction inclined upward, and a second inclined portion 59 located downstream from the first inclined portion 58 and having the trailing end portion in the horizontal direction inclined further upward. Depending on its size, each document 25 discharged onto the discharge tray 31 by the pair of discharge rollers 56 is discharged with the gravity to the first inclined portion 58 and the second inclined portion 59 of the discharge tray 31.

As illustrated in FIG. 2, the image reading device 3 includes a first size sensor 101 that detects the size of the documents 25 in the sub-scanning direction at the document tray 28 that receives the documents 25, and second to fifth size sensors 102 to 105 that detect the size of the documents 25 in the main scanning direction.

The sizes of the documents 12 and 25 carrying images readable by the image reading device 3 have been varied in accordance with user needs. Particularly, in recent years, documents carrying images readable by the image reading device 3 have been shifted toward a smaller size range, such as a waybill of TA-Q-BIN (registered trademark), a promissory note, a check, a receipt, or a boarding pass.

Generally speaking, an increase of the size of the document carrying an image readable by the image reading device 3 increases the number of size sensors attached to the document tray 28.

As described above, as an example of the technology relating to the size detection of the document 25 placed on the document tray 28, the device has been disclosed in Japanese Unexamined Patent Application Publication No. 2014-118282.

The device disclosed in Japanese Unexamined Patent Application Publication No. 2014-118282, however, involves additional installation of a final document detector that detects the final document on the sheet receiver. Thus, the device has a technical issue of an increase of the number of detectors disposed at the sheet receiver.

The image reading device according to the first exemplary embodiment includes a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction, a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path, and a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present. The second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.

Specifically, as illustrated in FIG. 2, the image reading device 3 according to the first exemplary embodiment simply includes a first size sensor 101 at the document tray 28, as a detector that detects the size of the document 25 in the sub-scanning direction. The first size sensor 101 is located at a center portion in the direction crossing the transport direction of the document 25, and at a position apart from the stop plate 32 by a predetermined distance L1 in the transport direction of the document 25. The distance L1 is a value (approximately 310 mm) of the size (dimension) of the document 25 in A4 in the longitudinal direction slightly longer by a length ΔL than a length of the A4 size in the longitudinal direction. Thus, when the first size sensor 101 is turned on in response to placing the document 25 on the document tray 28, the size (dimension) of the document 25 in the transport direction is longer than the length (297 mm) of the A4 size in the longitudinal direction.

As illustrated in FIG. 2, in the image reading device 3 according to the first exemplary embodiment, the path length of the document transport path 40 from the sheet pass sensor 107 to the leading-end sensor 109 in the transport direction of the document 25 is slightly shorter than a length L2 (210 mm) of the document 25 in A4 in the lateral direction by a length ΔL2. Thus, when the leading end of the document 25 in A4 in the lateral direction arrives at the leading-end sensor 109 after being detected by the sheet pass sensor 107, the sheet pass sensor 107 is turned on. In contrast, when the leading end of a document 25 shorter than the document 25 in A4 in the lateral direction arrives at the leading-end sensor 109 after being detected by the sheet pass sensor 107, the sheet pass sensor 107 is turned off.

Thus, the image reading device 3 according to the first exemplary embodiment is capable of determining whether the length of the document 25 in the transport direction is greater than or equal to the length L2 (210 mm) of the A4 size in the lateral direction by determining whether the sheet pass sensor 107 is turned on or off when the leading end of the document 25 is detected by the sheet pass sensor 107 and arrives at the leading-end sensor 109. The determination as to whether the size is smaller than or equal to a predetermined length is to determine whether the document 25 has a length L2 (210 mm) of the A4 size in the lateral direction.

FIG. 7 is a block diagram of a control device included in the image reading device 3 according to the first exemplary embodiment.

A control device 200 in FIG. 7 controls the operation of the image reading device 3. The control device 200 includes a central processing unit (CPU) 201 as an example of a controller that controls the operation of the image reading device 3, a read only memory (ROM) 202 that stores, for example, programs executed by the CPU 201, a random access memory (RAM) 203 that temporarily stores, for example, parameters used in the programs, a bus 204 that connects components including the CPU 201 and the ROM 202, and a communication interface 205 that performs communications with a control device of the image forming apparatus 1 not illustrated.

The CPU 201 receives detection signals from the first to fifth size sensors 101 to 105, the sheet pass sensor 107, the jam sensor 108, and the leading-end sensor 109. The CPU 201 determines the size of the document 25 placed on the document tray 28 of the image reading device 3 based on the detection signals from the first to fifth size sensors 101 to 105, the sheet pass sensor 107, the jam sensor 108, and the leading-end sensor 109, with reference to the table illustrated in FIG. 6 preliminarily stored in the ROM 202.

An operation device 206 operates the image forming apparatus 1 including the image reading device 3. As illustrated in FIG. 1, the operation device 206 is disposed at, for example, a front surface of the image reading device 3. The operation device 206 includes an input unit 207 and a display 208. The input unit 207 allows a user to input, for example, the type of the recording sheet 4 on which an image is formed by the image forming apparatus 1 or the number of the recording sheets 4, and allows a user to select and designate a reading mode specifying whether the image reading device 3 reads the image on the document simply on one surface (the top surface) or on both surfaces, or reads the image on the document in full color or in monochrome. The display 208 displays, for example, the input type of the recording sheet 4 or the input number of the recording sheets 4, or the reading mode of the image on the document.

Operation of Image Reading Device

Compared to a structure additionally including a final document detector that detects a final document on the sheet receiver, the image reading device according to the first exemplary embodiment is capable of detecting the size of a sheet smaller than or equal to a predetermined length in the transport direction in the manner described below without increasing the number of detectors disposed at the sheet receiver.

Specifically, as illustrated in FIG. 2, in the image reading device 3 according to the first exemplary embodiment, one or more documents 25 each carrying an image to be read are placed on the document tray 28. The one or more documents 25 are placed while having the leading ends in the read direction abutting against the stop plate 32 of the document tray 28, and while having both edges in the width direction crossing the read direction of the document 25 abutting against the side guides 33 and 34.

As illustrated in FIG. 1, in the image reading device 3, when a user selects an operation including the read operation of the document 25 through the input unit 207 and the display 208 of the operation device 206 and presses a start button of the input unit 207 not illustrated, as illustrated in FIG. 8, the leading end of the document tray 28 in the transport direction tilts to come into contact with the nudger roller 41.

At this time, as illustrated in FIG. 2, in the image reading device 3, the first to fifth size sensors 101 to 105 detect the size of the document 25 placed on the document tray 28 in the sub-scanning direction and the main scanning direction.

Thereafter, the image reading device 3 drives the nudger roller 41 to rotate to start transporting the uppermost one of the documents 25 placed on the document tray 28.

The CPU 201 of the control device 200 determines whether the size of the document 25 in the transport direction is longer than the first length (310 mm) based on the detection signals from a first size sensor 101. The CPU 201 of the control device 200 also determines which of the groups 1 to 12 the size of the document 25 in the main scanning direction falls under based on the detection signals from the second to fifth size sensors 102 to 105.

After starting transporting each document 25, and when the leading end of each document 25 passes the sheet pass sensor 107 and arrives at the leading-end sensor 109, the CPU 201 of the control device 200 determines whether the sheet pass sensor 107 is turned on or off.

The CPU 201 of the control device 200 determines the size of the documents 25 with reference to the table illustrated in FIG. 6 and based on the detection signals from the first size sensor 101, the detection signals from the second to fifth size sensors 102 to 105, and whether the sheet pass sensor 107 and the leading-end sensor 109 are turned on or off.

More specifically, the CPU 201 of the control device 200 determines which of the groups 1 to 12 the size of each document 25 falls under based on the detection signals from the second to fifth size sensors 102 to 105.

The CPU 201 of the control device 200 then determines the detection signals from the first size sensor 101 and whether the sheet pass sensor 107 and the leading-end sensor 109 are turned on or off, that is, whether the sheet pass sensor 107 is turned on or off when the leading-end sensor 109 is turned on.

In the first exemplary embodiment, whether the sheet pass sensor 107 is turned on or off is determined when the leading-end sensor 109 is turned on, but this is not the only possible example. When the documents 25 are transported at a known uniform speed, time T taken from when the leading end of each document 25 passes the sheet pass sensor 107 to when the leading end arrives at the leading-end sensor 109 may be preliminarily stored in the ROM 202 to be used as a reference.

When multiple lengths of time T taken from when the leading end of each document 25 passes the sheet pass sensor 107 to when the leading end arrives at the leading-end sensor 109 are set in advance, the size of the documents 25 in the transport direction may be determined from among multiple sizes.

In this manner, compared to a structure additionally including a final document detector that detects a final document on the sheet receiver, the image reading device 3 according to the first exemplary embodiment is capable of detecting the size of the document 25 smaller than or equal to a predetermined length in the transport direction without increasing the number of detectors disposed at the document tray 28 serving as a sheet receiver, or while reducing the number of detectors disposed at the document tray 28 in the first exemplary embodiment.

Second Exemplary Embodiment

In an image reading device 3 according to a second exemplary embodiment of the present disclosure, a path length of the document transport path 40 from the sheet pass sensor 107 to the leading-end sensor 109 in the transport direction of the document 25 is longer than a length L2 (210 mm) of the document 25 in A4 in the lateral direction instead of the value slightly shorter than the length L2 (210 mm) of the document 25 in A4 in the lateral direction by the length ΔL2. In addition, as timing to detect whether the trailing end of each document 25 has passed the sheet pass sensor 107, timing when the jam sensor 108 is turned on is also employed in addition to timing when the leading-end sensor 109 is turned on to simultaneously detect multiple sizes of the documents 25 in the transport direction.

Other components and operations are the same as those of the above exemplary embodiment, and thus are not described.

The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.

APPENDIX

• • (((1))) A sheet transporting device, comprising:
  • a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction;
  • a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and
  • a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present, wherein the second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.
  • (((2))) The sheet transporting device according to (((1))), wherein the second detector is disposed most upstream at the sheet transport path in the sheet transport direction.
  • (((3))) The sheet transporting device according to (((2))), wherein the predetermined length is shorter than a length along the sheet transport path from the second detector to the image read position.
  • (((4))) The sheet transporting device according to (((1))), wherein the first detector detects that the sheet received on the sheet receiver has a larger size than a length of an A4 size in a longitudinal direction.
  • (((5))) The sheet transporting device according to (((4))), wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined based on whether a trailing end of the sheet has passed the second detector before a leading end of the sheet arrives at the image read position.
  • (((6))) The sheet transporting device according to (((5))), wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined simply when the first detector does not detect the sheet received on the sheet receiver.
  • (((7))) An image reading device, comprising:
  • an image reading member that reads an image on a sheet; and
  • a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,
  • wherein the sheet transporting device according to any one of (((1))) to (((6))) is used as the sheet transport member.
  • (((8))) An image forming apparatus, comprising:
  • the image reading device according to (((7))) that reads an image on a sheet; and
  • an image recording device that records the image on the sheet read by the image reading device on a recording medium.

Claims

1. A sheet transporting device, comprising:

a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction;

a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and

a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present,

wherein the second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.

2. The sheet transporting device according to claim 1, wherein the second detector is disposed most upstream at the sheet transport path in the sheet transport direction.

3. The sheet transporting device according to claim 2, wherein the predetermined length is shorter than a length along the sheet transport path from the second detector to the image read position.

4. The sheet transporting device according to claim 1, wherein the first detector detects that the sheet received on the sheet receiver has a larger size than a length of an A4 size in a longitudinal direction.

5. The sheet transporting device according to claim 4, wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined based on whether a trailing end of the sheet has passed the second detector before a leading end of the sheet arrives at the image read position.

6. The sheet transporting device according to claim 5, wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined simply when the first detector does not detect the sheet received on the sheet receiver.

7. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 1 is used as the sheet transport member.

8. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 2 is used as the sheet transport member.

9. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 3 is used as the sheet transport member.

10. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 4 is used as the sheet transport member.

11. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 5 is used as the sheet transport member.

12. An image reading device, comprising:

an image reading member that reads an image on a sheet; and

a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,

wherein the sheet transporting device according to claim 6 is used as the sheet transport member.

13. An image forming apparatus, comprising:

the image reading device according to claim 7 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

14. An image forming apparatus, comprising:

the image reading device according to claim 8 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

15. An image forming apparatus, comprising:

the image reading device according to claim 9 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

16. An image forming apparatus, comprising:

the image reading device according to claim 10 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

17. An image forming apparatus, comprising:

the image reading device according to claim 11 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

18. An image forming apparatus, comprising:

the image reading device according to claim 12 that reads an image on a sheet; and

an image recording device that records the image on the sheet read by the image reading device on a recording medium.

19. A sheet transporting device, comprising:

sheet receiving means for receiving a sheet and including first detection means for detecting a size of the sheet in a transport direction;

sheet transport means for transporting the sheet received on the sheet receiving means to an image read position along a sheet transport path; and

second detection means disposed in front of the image read position on the sheet transport path for detecting whether any sheet is present,

wherein the second detection means determines whether the sheet received on the sheet receiving means has a size smaller than or equal to a predetermined length in the transport direction.