JPH08254763A - Automatic document feeder - Google Patents

Abstract

PURPOSE: To provide a small-sized, inexpensive and automatic document feeder capable of picking up a both-side document from a contact glass based on detection information by one detecting means for detecting the leading and trailing ends of the document. CONSTITUTION: A regist sensor 28 for detecting the leading and trailing ends of the document is installed on the upstream side of a feeding means 15 in the document feeding direction, and also, the feeder is provided with a control means 34 for picking up the document P from the glass 4 based on the information on the detection of the leading end of the document by the sensor 28 at the time of feeding the document toward a paper ejecting means 16 by an endless belt 36, and also for picking up the document P from the glass 4 based on the information on the detection of the trailing end of the document P by the sensor 28 at the time of feeding the document P toward a switchback means 18 by the endless belt 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder, and more specifically, it moves when reading a document that is stationary on the contact glass, and at a predetermined time when reading a document that is carried on the contact glass. The present invention relates to an automatic document feeder which is provided in an image reading apparatus having a reading unit configured to stop at the reading position and which can feed a document to the predetermined reading position and discharge the read document.

[0002]

2. Description of the Related Art Conventionally, there are various methods for reading an original by an image reading apparatus such as a copying machine or a scanner, and various automatic original feeding apparatuses corresponding to the reading method have been developed. For example, when the reading optical system is moved (scanned) to read a document, the document is conveyed to the contact glass by the automatic document feeder and stopped on the contact glass, and the reading optical system is moved in this state to move the document. After reading the document, there is a device in which the sheet is discharged to the outside (for example, Japanese Utility Model Laid-Open No. 62-63255, JP-A-33040).
(See the official gazette). With this, when reading a book document, etc., after opening the automatic document feeder from the contact glass and placing the document on the contact glass, the automatic document feeder covers the contact glass and reads it. The original is read by moving the optical system.

However, in such an automatic document feeder, since a long conveyor belt is required to convey the entire surface of the original onto the contact glass, the size of the conveying apparatus becomes large, and the reverse path and stack of the originals are required. Since the region must be installed beside the contact glass, there is a problem that the device becomes even larger. Further, since the document is conveyed to the contact glass and then read by resting the document, the document reading performance is very poor.

As a solution to such a problem, there is a so-called sheet-through type automatic document feeder for reading a document while feeding it to a fixed reading optical system (for example, Japanese Utility Model Laid-Open No. Sho 58-180828). Japanese Patent Laid-Open Publication No. 2-112642 and Japanese Laid-Open Patent Publication No. 2-198941). This one can read the original surface by the reading optical system fixed through the slit glass by conveying the original to the narrow slit glass without keeping the original still on the contact glass. Since the reading performance is improved and a long conveyor belt is not necessary, the device can be downsized.

However, in such an automatic document feeder, since there is no contact glass, a book document or the like cannot be read, and the versatility is lacked. Therefore, recently, various image reading apparatuses capable of reading both book originals and sheet through originals have been developed. This device moves when reading a document that is stationary on the contact glass, and a reading unit that is configured to stop on the slit glass when reading the document that is being conveyed, and a reading unit that is located at the predetermined reading position. It is provided with an automatic document feeder that can convey a document and discharge the read document (see, for example, Japanese Patent Laid-Open No. 2-48679).

However, in this case, a slit glass for reading the sheet-through original is required in addition to the contact glass, so that the apparatus becomes large and costly. On the other hand, 1
There is one in which a book document and a sheet-through document are read by two contact glasses (Japanese Patent Laid-Open No. HEI 2-
No. 77075), this one has a reading optical system that moves when reading a document that is stationary on the contact glass and stops at the end of the contact glass when reading a document that is conveyed, When reading a sheet-through original, the original placed on the original table is conveyed toward the edge of the contact glass, and the original after being read at the edge of the contact glass is conveyed from the edge of the contact glass by the conveyance rollers. It is designed to be carried out and discharged onto a discharge tray on the side of the apparatus body. In this case, the apparatus can be made compact and low in cost because the book original and the sheet through original can be read by one contact glass.

[0007]

However, in the image reading apparatus having such a conventional automatic document feeder, the document after being read at the edge of the contact glass is fed from the edge of the contact glass. Since it is carried out by rollers and discharged onto the discharge tray on the side of the main body of the device, it is possible to install a discharge tray on the side of the main body or to pick up documents on the discharge tray on the side of the main body. There is a problem in that the automatic document feeder is lengthened in the longitudinal direction by the area required for the mechanism, which increases the installation space of the image reading apparatus.

Therefore, according to the first aspect of the present invention, the sheet-through original is scooped up on the pressing cover above the contact glass and discharged, and the scooped original is switched back to be returned to the contact glass reading position. In this way, a double-sided original can be conveyed with a short length in the longitudinal direction, and a double-sided original can be scooped up from the contact glass based on the detection information from one detecting means for detecting the front and rear ends of the original. It is also an object of the present invention to provide a low cost automatic document feeder.

According to the second aspect of the invention, the original can be reliably picked up from the contact glass, and
An object of the present invention is to provide an automatic document feeder which can prevent the endless belt from changing its conveying speed by conveying an original in this state and can read the original with high accuracy.

[0010]

According to the first aspect of the present invention,
In order to solve the above-mentioned problem, a reading configured to move when reading a document that is stationary on the contact glass, and to stop at a predetermined reading position when reading a document conveyed on the contact glass In an automatic document feeder provided in an image reading apparatus having a means, a pressing cover for pressing an original placed on a contact glass against the contact glass, and a plurality of originals placed above the pressing cover are placed. A possible document placing table and a document feeding port are formed on the end side of the contact glass, and the document stack placed on the document placing table is fed from the paper feeding port.
Separation / conveying means for separating the originals one by one from the bundle of documents and inverting the separated originals and conveying them to a predetermined reading position; and a separation / conveying means for conveying the originals to a predetermined reading position. A conveying means having an endless belt for conveying an original document to the reading position, a scooping means for forming an unequal electric field on the endless belt, sucking the original document by the endless belt and scooping it up from the contact glass, A sheet discharging unit that discharges the document picked up by the scooping unit onto the pressing cover, and a document that is provided adjacent to the sheet discharging unit and that conveys the document scooped by the scooping unit to the switchback passage, and then the conveying path. The switchback means for returning the sheet to the endless belt and the upstream side of the switchback means and the paper discharge means in the document conveying direction, and the scooping A switching means for switching the conveying direction so that the original picked up by the steps is conveyed to either the switchback means or the paper discharge means, and the front and rear edges of the original are provided upstream of the conveying means in the original conveying direction. And a contact glass for controlling the scooping means based on the front edge detection information of the document from the detecting means when the document is conveyed toward the switchback means by the conveying means during the conveyance of the double-sided original. When the original returned from the switchback means is conveyed to the paper discharging means by the conveying means while the original is scooped from the switchback means, the scooping means is controlled based on the rear end detection information of the original from the detecting means to control the contact glass. It is characterized by comprising control means for picking up the document from.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, in the first aspect of the present invention, the conveying means is separated from each other on the upstream side and the downstream side in the conveying direction of the original of the endless belt. An endless belt is provided and a pair of belt conveying rollers are provided, and the scooping means fulcrums the belt conveying roller on the downstream side in the document conveying direction among the belt conveying rollers and the belt conveying roller on the upstream side in the conveying direction. It is characterized in that it comprises an approaching and spacing member for approaching and spacing the contact glass and an applying member for applying an alternating voltage to the endless belt.

[0012]

According to the invention described in claim 1, after being separated by the separating / conveying means, it is conveyed toward a predetermined reading position,
The original read at the reading position is picked up from the contact glass and conveyed to either one of the paper discharge means or the switchback means. Then, after the document whose front surface has been read during the conveyance of the double-sided document is picked up above the contact glass by the scooping means, the conveyance path is switched to the switchback means side and conveyed to the switchback passage. , Is returned to the endless belt via the transport path, and is returned to the reading position of the contact glass again. Next, the document whose back surface has been read is scooped up above the contact glass by the scooping means, and then the paper discharge path is switched to the paper discharge means side and is discharged onto the presser cover.

Therefore, since the original is picked up and discharged to the discharge means or the switchback means,
The structure between the transport means, the paper discharge means, and the switchback means is simplified to reduce the space of the document transport path, and the document is discharged to the discharge tray on the side of the image reading apparatus body as in the conventional case. Since the paper is not printed, the length of the automatic document feeder in the longitudinal direction is shortened, and the double-sided document can be transported in a small space. As a result, the automatic document feeder can be downsized and its cost can be reduced. Further, since the document returned from the switchback path by the switchback means is directly returned to the endless belt via the transport path, the switched-back document is returned via the short transport path, and the transport time is shortened.

Further, detection means for detecting the front and rear edges of the original are provided upstream of the conveying means in the original conveying direction, and
When a double-sided original is conveyed, when the original is conveyed toward the switchback means by the conveying means, the scooping means is controlled based on the front end detection information of the original from the detecting means to scoop the original from the contact glass. When the document returned from the switchback unit is conveyed to the sheet discharging unit by the conveying unit, the scooping unit is controlled based on the trailing edge detection information of the document from the detecting unit and the document is scooped from the contact glass. .

Therefore, the automatic document conveyance does not occur because the document is picked up from the contact glass when the double-sided document is conveyed on the basis of the detection information from one detecting means, and the number of the detecting means is increased and the cost thereof is not increased. The device becomes even cheaper. Further, since the original is scooped up from the contact glass when the double-sided original is conveyed based on the detection information of the front and rear edges of the original, the double-sided original is surely scooped up from the contact glass regardless of the size of the double-sided original.

According to a second aspect of the invention, the conveying means has a pair of belt conveying rollers provided separately on the upstream side and the downstream side of the endless belt in the conveying direction of the original, and suspending the endless belt. The scooping means forms an endless belt with a proximity separating member that separates the belt conveying roller on the downstream side in the document conveying direction from the belt conveying rollers toward and away from the contact glass with the belt conveying roller on the upstream side in the conveying direction as a fulcrum. And an application member for applying an alternating voltage.

Therefore, since the original is sucked by the flat surface of the endless belt, the adhesion of the original is improved, and the original is picked up from the contact glass and conveyed in a stable state. Further, when the original is picked up from the contact glass, the belt conveying roller on the upstream side in the conveying direction of the original is separated from the contact glass by using the belt conveying roller on the upstream side in the conveying direction as a fulcrum. The rotational speed of the endless belt does not change due to the rotation of the document, and the document is read with high accuracy by the reading unit of the image forming apparatus.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 are views showing a first embodiment of an image reading apparatus according to the invention described in claim 1 or 2. First, the configuration will be described. 1 to 3, reference numeral 1 denotes a scanner device as an image reading device, and this scanner device is a reading unit 2
And an automatic document feeder 3.

The reading unit 2 includes a main body 2a having a contact glass 4 on its upper surface, a light source 5 housed in the main body 2a, which is a fluorescent lamp or a halogen lamp for irradiating a document through the contact glass 4, and a light source. A plurality of mirrors 6 to 8 that reflect the light applied to the document, a lens 9 that collects the reflected light, a light that is collected by the lens 9 is read, and an analog signal is converted into a digital signal, which is not shown. The image pickup device 10 is composed of a CCD or the like for outputting to an image forming device.

The light source 5 and the mirrors 6 to 8 move in the left-right direction in FIG. 1 along the extension direction of the contact glass 4 to read a book document or the like which is stationary on the contact glass 4, and in FIG. A sheet-through document, which will be described later, is read by stopping at the left end, and the stop position is the contact glass 4 as shown by the one-dot chain line in FIG.
Is set in the reading area S of. The light source 5, the plurality of mirrors 6 to 8, the lens 9 and the image pickup device 10 described above constitute a reading unit.

Further, an automatic document feeder 3 is provided on the main body 2a of the reading section 2 so as to open and close with respect to the contact glass 4 so as to cover the contact glass 4. The automatic document feeder 3 has a holding cover 11 for holding the document placed on the contact glass 4 against the contact glass 4.
And a document tray 12 as a document placing table on which a plurality of sheet documents can be placed, and the document stacks placed on the document tray 12 are separated one by one, and the separated documents are inverted to perform a predetermined reading. Separating / conveying means 13 for conveying toward the position, and the original conveyed by the separating / conveying means 13 toward the predetermined reading position is conveyed to the reading position, and the original read at the reading position is conveyed. Scoop up the contact glass 4
Conveying means 15 having scooping means 14 separated from
And a discharge means for discharging the originals picked up by the scooping means 14 to the discharge tray 11a on the pressing cover 11.
16 and a switchback means which is provided adjacent to the paper discharge means 16 and which conveys the original document picked up by the scooping means 14 to the switchback passage 17 and then turns it over toward the reading position of the contact glass 4 and returns it. 18 is provided on the upstream side of the switchback means 18 and the paper discharge means 16 in the original conveyance direction, and the original picked up by the scooping means 14 is conveyed so as to be conveyed to either the switchback means 18 or the paper discharge means 16. And a switching claw 19 as switching means for switching the direction.

The presser cover 11 is composed of a pressure contact pad in which a sheet 21 is attached to the surface of a resin foam member 20,
The sheet 21 has a surface and a material made of a coloring material that exhibits a uniform spectral response over the visible wavelength region, and is provided over the region showing most of the contact glass 4. Further, the document tray 12 is provided above the pressing cover 11, and a document stack made of a plurality of sheet documents is placed on the document tray 12.

The separating / feeding means 13 is a pickup roller 2
2, a document set sensor 23, separation rollers 24a and 24b, pressure rollers 25 and 26, a paper feed drive roller 27, a registration sensor 28, and a guide plate 29. Pickup roller 22
Is configured to feed the document stack placed on the document tray 12 through a paper feed port 30 formed on the end side of the contact glass 4, and is driven by a paper feed clutch 31. There is. The document set sensor 23 detects that a document is set on the document tray 12 and outputs a signal to the control means 34.

Separation rollers 24a and 24b are pickup rollers 22.
The uppermost document is separated from the bundle of documents fed by the separation clutch when separating.
Only the upper separating roller 24a is driven in the clockwise direction by 32, the lower separating roller 24b is stopped, and the separating clutch 31 is disengaged after separating the originals so that both rollers 24a and 24b idle. There is.

The paper feed drive roller 27 is driven by a main motor 33, and guides the separated originals to the end of the contact glass 4 along a curved guide plate 29 so as to form an inversion path. It is designed to be transported. Further, the pressure rollers 25 and 26 are pressed against the reversing drive roller 27 with a predetermined pressing force, and the document is nipped and conveyed together with the reversing drive roller 27. Therefore, the original on the paper feed tray 12 is reversed and conveyed toward the end of the contact glass 4.

The registration sensor (front and rear edge detection sensor) 28 detects the front and rear edges of the document conveyed along the guide plate 29 and outputs detection information to the control means 34. The control means is a CPU (Central Processing Unit),
RAM (Random Access Memory), ROM (Read Only M
emory) and the like, and controls the entire automatic document feeder 3 according to a predetermined program stored in the ROM.

When the start key is pressed and the document set sensor 23 detects that a document is set on the document tray 12, the control means 34 drives the paper feed clutch 31, the separation clutch 32 and the main motor 33. When the front edge of the document is detected by the registration sensor 28, the separation rollers 24a and 24b are made to idle based on the detection information. Further, the control means 34 is adapted to detect the length of the original in the conveyance direction based on the detection information of the front and rear edges of the original.

The conveying means 15 includes an endless belt 36, a belt driving roller 37 (belt conveying roller), and this driving roller.
It is composed of a stretching roller (belt conveying roller) 38 provided on the downstream side with respect to the document conveying direction with respect to 37. The endless belt 36 has a double-layered structure in which the front surface is made of a dielectric material and the back surface is made of a low-resistance layer. The surface dielectric material is made of a coloring material that shows an even spectral response over the visible wavelength range. And the material is used, the surface is a sheet
It has the same color as 21.

One end portion of the endless belt 36 is wound around the belt driving roller 37, and the roller 37 is driven in the counterclockwise direction by the main motor 33, and the endless belt 36 is driven.
It is designed to move 36. Further, a predetermined tension is applied to the belt drive roller 37 to press the endless belt 36 against the contact glass 4 with a constant pressure.

In this embodiment, the belt driving roller 37
And the contact glass 4 which comes into contact with the driving roller 37 via the endless belt 36 constitutes a predetermined reading position. This reading position is set when the end of the document on the contact glass 4 is positioned on the reference scale 40. Also, it corresponds to the reading start position of the document. In addition, the stretch roller 38 has an endless belt 36.
The other end of is stretched and the stretch roller 38 is moved vertically by a scooping solenoid 41 with the belt drive roller 37 as a fulcrum. Further, when the stretch roller 38 is moved downward by the scooping solenoid 41 so as to bring the endless belt 36 into contact with the contact glass 4, the stretch roller 38 comes close to the end of the presser cover 11 (see FIG. 2).

Further, as shown in FIG.
An electrode roller 42 is provided in a portion that contacts the outer peripheral surface of the endless belt 36 through 37, and an AC voltage (alternating voltage) is applied to the electrode roller 42 from an AC power supply 43. . The electrode roller 42 can move together with the stretching roller 38. The endless belt 36 is moved at a constant speed vmm / s in the direction of arrow A in FIG. 4A by the belt driving roller 37, and the document feeding position is the electrode roller 42 with respect to the moving direction of the endless belt 36. The area is in contact with the electrode roller 42 as a counter electrode on the downstream side of the contact position.

For this reason, an AC voltage is applied to the endless belt 36 via the electrode roller 42 by the AC power source 43 before the original is fed to the surface thereof, whereby the surface of the endless belt 36 is applied. , Charge density + σ, −σ are alternately v
An electric field density pattern arranged at a pitch of / Amm is formed. A similar charge density pattern is also formed on the back surface of the endless belt 36 with a 180 ° shift. Due to the charge density pattern thus formed, an unequal electric field is formed near the surface of the endless belt 36 as shown in FIG. 4B.
Due to this electric field, the document P is electrostatically attracted to the endless belt 36 by the component of Fx of the derivative of the endless belt 36 and held without being displaced, and is conveyed along with the endless belt 36. The scooping solenoid 41, the electrode roller 42, and the AC power source 43 described above constitute scooping means for scooping up the document read at the reading position and separating it from the contact glass 4, and among them, the scooping solenoid.
Reference numeral 41 constitutes a proximity separating member, and an electrode roller 42 and an AC power source 43
Constitutes an application member.

The guide plates 39a and 39b are endless belts.
The guide plates 39a, 39b are provided above the 36, and form a conveyance path for conveying the document switched back from the switchback passage 17 toward the conveyance means 15.
The paper discharge unit 16 includes a drive roller 44, a pressure roller 45 pressed by the drive roller 44, and a paper discharge sensor 46. The driving roller 44 is rotated in the forward and reverse directions by the reversing driving motor 47, and when the stretching roller 38 is moved upward by the scooping solenoid 41 so as to be separated from the contact glass 4, the driving roller 44 rotates counterclockwise. The original is nipped together with the pressure roller 45 by being driven in the direction, and the scooped-up original is discharged onto the discharge tray 11a through the discharge port 48. The paper discharge sensor 46 is provided in the vicinity of the paper discharge port 48, and detects the rear end of the document discharged onto the paper discharge tray 11a and outputs a signal to the control means 34.

The switchback means 18 is provided adjacent to the paper discharge means 16 and includes a drive roller 44 and this drive roller.
It is composed of a pressure roller 49 and a tension roller
When the 38 is moved upward by the scooping solenoid 41 so as to be separated from the contact glass 4, the drive roller
The reversing drive motor 47 drives the reversing drive motor 47 in the clockwise direction to sandwich the original document together with the pressure roller 49, and convey the scooped original document to the switchback passage 17. The switchback passage 17 is provided below the document tray 12 integrally with the document tray 12, and is composed of a space.

When the document is conveyed to the switchback passage 17, the reversing drive motor 47 is driven in the counterclockwise direction, and the document is switched back from the switchback passage 17 to be fed through the guide plates 39b and 39a. It is designed to be flipped over to the reading position and returned. In this example,
The members forming the above-mentioned conveying means 15 also form the switchback means.

On the other hand, the switching claw 19 is provided on the upstream side of the switchback means 18 and the paper discharge means 16 in the original conveying direction, and the original picked up by the endless belt 36 is placed between the drive roller 44 and the pressure roller 45. Further, it is driven by the switching solenoid 51 so as to switch the carrying direction so as to carry it to one side between the drive roller 44 and the pressure roller 49.

The switching solenoid 51 switches the switching claw 19 based on a signal from the control means 34.
When the double-sided mode is designated by the mode selection unit 50 and the registration sensor 28 detects the leading edge of the document, the control means 34 controls the switching solenoid 51 to drive the switching claw 19 to drive the roller.
The drive roller 44 is driven in the clockwise direction while being set to a switching position so as to form a communication path communicating between the 44 and the pressure roller 49.

The control means 34 operates when the number of rotations of the main motor 33 reaches a predetermined pulse or when a predetermined time elapses after the registration sensor 28 detects the trailing edge of the document (this pulse or time is a switch). The number of pulses or the time is set so that the document is surely stored in the back passage 17), the switching claw 19 is set to the drive roller 44 and the pressure roller.
The switching solenoid 51 is controlled so that the switching position is such that a communication path is formed between 49 and the guide plate 39a, and the drive roller 44 is driven in the counterclockwise direction to drive the document in the switchback path 17. Is reversed through the guide plates 39b and 39a and returned.

Further, when the single-sided mode is designated by the mode selection unit 50 and when the back side is read in the double-sided mode, the control means 34 determines the rotation speed of the main motor 33 after the registration sensor 28 detects the leading edge of the document. When the specified pulse is reached or the specified time has elapsed, the switching solenoid
51 to control the switching pawl 19 so that the endless belt 36 and the drive roller 44
Further, the driving roller 44 is driven in the counterclockwise direction while being switched to a switching position so as to form a communication path communicating between the pressure rollers 45.

The control means 34 is provided in the reading section 2 when the number of rotations of the main motor 33 reaches a predetermined pulse or when a predetermined time elapses after the registration sensor 28 detects the leading edge of the document. When a signal is output to the reading control means 52 to cause the reading unit 2 to start reading a document, and the number of rotations of the main motor 33 reaches a predetermined pulse after the registration sensor 28 detects the trailing edge of the document, or a predetermined number of pulses. When the time has elapsed, a signal is output to the reading control means 52 and the reading unit 2
The reading of the document by is ended.

Further, the control means 34 specifies the double-sided mode by the mode selection section 50, and when the front side of the double-sided original is read by the scanner device 1, or the mode selection section 50.
When the single-sided mode is designated by the scanner 1 and the front side of the document is read by the scanner device 1, the number of rotations of the main motor 33 reaches a predetermined pulse A after the registration sensor 28 detects the leading edge of the document, or for a predetermined time. When the time T has elapsed, the scooping solenoid 41 moves the stretch roller 38 in a direction to separate it from the contact glass 4, and the endless belt 36 scoops the document from the contact glass 4. The pulse A and the time T are set to correspond to the distance or time from the registration sensor 28 until the front surface of the original is sufficiently adsorbed by the endless belt 36.

Further, when the double-sided mode is designated by the mode selection unit 50 and the both sides of the both sides are read by the scanner device 1, the control means 34 detects the trailing edge of the original document and then the main motor 33 of the main motor 33. When the number of rotations reaches a pulse A1 larger than the predetermined pulse A, or when a predetermined time T1 longer than the predetermined time T has elapsed, the scooping solenoid 41 moves the stretching roller 38 in a direction to separate it from the contact glass 4. Endless belt
The document 36 is picked up from the contact glass 4 by the 36. This pulse A1 and time T1
Is set to correspond to the distance or time until the document is switched back from the registration sensor 28 and the front surface of the document is sufficiently attracted to the endless belt 36 again.

In this embodiment, the contact pressure between the pressure roller 49 and the driving roller 44 is set to be smaller than the contact pressure between the pressure roller 45 and the driving roller 44. Next, the operation will be described with reference to FIGS. 5 to 7 are views for explaining the carrying operation, and FIG. 8 is a timing chart at the time of carrying the carrying operation, showing a timing chart at the time of carrying a double-sided original.

First, when reading only one original P such as a book original, the automatic original feeder 3 is opened from the contact glass 4, the original is placed on the contact glass 4, and the automatic original feeder 3 is set. close. At this time, as shown in FIG. 2, since the stretch roller 38 is moved to the position where it comes into contact with the contact glass 4 by the scooping solenoid 41, and a predetermined tension is applied to the belt drive roller 37, the presser cover is held. 12 with endless belt 36
Presses the document against contact glass 4. For this reason,
With the pressing cover 11 and the endless belt 36 having the same color, the document is stably pressed against the contact glass 4 without floating from the contact glass 4.

When the start switch is depressed in this state, the light source 5 and the mirrors 6 to 8 move below the contact glass 4 from the left end to the right end in FIG. Scan the original with 10. On the other hand, in the case of reading a sheet-through document, FIG.
When the document stack Pn is placed on the document tray 12 as shown in FIG.
Is detected. When the start switch is pressed in this state, the main motor 33 is driven, and the paper feed clutch 31 and the separation clutch 32 are driven so that the pickup roller 22 feeds the document bundle Pn through the paper feed port 30. Next, after the uppermost original P is separated from the original bundle Pn by the separation rollers 24a and 24b, the original P is nipped by the sheet feeding drive roller 27 and the pressure rollers 25 and 26 and is guided along the guide plate 29. Be transported. When the leading edge of the original P is detected by the registration sensor 28, the control means 34 stops driving the separating clutch 32 to prevent the succeeding original P from being separated (the paper feeding clutch 31 is separated by the separating clutch 32). Has stopped before). At the start of separation, the non-uniform electric field is applied to the endless belt 36 by the electrode roller 42 (see the high voltage power pack in the time chart of FIG. 8).

Next, the original P is conveyed between the belt driving roller 37, which is the reading position, and the contact glass 4. At this time, the number of pulses of the main motor 33 is counted by an amount corresponding to the distance from the registration sensor 28 to the reading position, and when the number of pulses reaches a predetermined pulse,
Alternatively, when a predetermined time elapses from the registration sensor 28 to the reading position, the reading control unit 52 is controlled to stop the light source 5 and the like below the reading position to start reading the document P.

Further, when the document P is conveyed to the reading position, the belt driving roller 37 is pressed against the contact glass 4 with a predetermined tension, so that the document P is prevented from being skewed. Next, when the number of pulses of the main motor 33 reaches a predetermined pulse number A after the leading edge of the document P is detected by the registration sensor 28, or a predetermined time T has elapsed after the leading edge of the document P was detected by the registration sensor 28. At this time, the front surface of the document P advances on the contact glass 4 by a certain distance so that the front end of the original P is sufficiently sucked by the endless belt 36. Then, the glass roller 4 is brought into contact with the glass 4, and the stretching roller 38 is moved upward. Therefore, the document P is sucked by the endless belt 36 and scooped up from the contact glass 4 (FIG. 5).
(See (b) and (c)).

Further, when the one-sided mode is designated based on the signal from the mode selection section 50, the control means 34 causes the switching solenoid 51 to switch the switching claw 19 when the leading edge of the document P is detected by the registration sensor 28. Switch the switching position,
The downstream side of the endless belt 36 in the document conveying direction is made to communicate between the drive roller 44 and the pressure roller 45, and the drive roller 44 is driven in the counterclockwise rotation direction. Therefore, the endless belt 36
The document P conveyed by the drive roller 44 and the pressure roller 45.
Output tray 11 through output outlet 48 while being pinched by
The sheet is discharged onto the sheet a (see FIG. 6A). Incidentally, after the registration sensor 28 detects the rear end of the document P, the main motor 33
When the number of pulses has reached a predetermined number of pulses, or when a predetermined time has elapsed, the control means 34 outputs a signal to the reading control section 52 and finishes reading the document P.

Here, when the document P is picked up, the contact glass 4 of the belt driving roller 37 and the stretching roller 38
On the side, that is, on the contact glass 4 side surface of the endless belt 36, the angle formed by the contact glass 4 is larger than the line connecting the tangent line between the driving roller 44 and the pressure roller 45 and the belt driving roller 38. The ability to convey the original P to the paper ejection port 48 is improved.

On the other hand, when the double-sided mode is designated on the basis of the signal from the mode selection section 50, the control means 34, when the leading edge of the document P is detected by the registration sensor 28, the document conveying direction of the endless belt 36. The downstream side is made to communicate between the drive roller 44 and the pressure roller 49, and the drive roller 44 is driven in the clockwise direction. Therefore, the document P conveyed by the endless belt 36 is nipped by the driving roller 44 and the pressure roller 49 and conveyed to the switchback passage 17 (see FIG. 6B).

Next, when the registration sensor 28 detects the trailing edge of the document P and when the number of pulses of the main motor 33 is counted enough to accommodate the document P in the switchback passage 17, or when a predetermined time elapses. When the control means
34 controls the switching solenoid 51 to drive the switching claw 19 to drive the roller.
The switching position is such that a communication path is formed between 44 and the pressure roller 49 and the guide plate 39a, and the drive roller 44 is driven in the counterclockwise direction to guide the document P in the switchback path 17. It is inverted through the plates 39b and 39a and returned to the reading position (see FIG. 6C).

Then, the control means 34 moves from the detection of the trailing edge of the original P by the registration sensor 28 to the main motor 33 until the original P which is reversed and returned moves to the reading position again.
The number of pulses is counted, and when the count value is reached, or when a predetermined time has elapsed after the trailing edge of the document P was detected by the registration sensor 28, the reading unit 2 starts reading the document P. In addition, the registration sensor 28
After the trailing edge of the document P is detected by the main motor 33
When the number of pulses of the original P has reached a predetermined number of pulses A1, or a predetermined time T1 has elapsed since the trailing edge of the original P was detected by the registration sensor 28, the original P comes into contact glass 4
When the vehicle has advanced a certain distance, the control means 34 drives the scooping solenoid 41 to move the stretch roller 38 toward the contact glass 4 and bring it into contact with the glass 4, and then the stretch roller 38 is moved upward. Move to. Therefore, the document P is sucked by the endless belt 36 and is picked up again from the contact glass 4 (see FIGS. 7A and 7B).

Then, the control means 34 switches the switching position of the switching claw 19 by the switching solenoid 51 at the time of outputting the scooping signal, and the downstream side of the endless belt 36 in the document conveying direction is driven by the drive roller 44 and the pressure roller 45. While communicating between
The drive roller 44 is driven counterclockwise. For this reason,
The document P conveyed by the endless belt 36 is a driving roller.
The paper is ejected onto the paper ejection tray 11a through the paper ejection port 48 while being sandwiched by the 44 and the pressure roller 45 (see FIG. 7B).
Next, when the trailing edge of the document P is detected by the paper discharge sensor 46, the paper feed clutch 31 and the separation clutch 32 are driven again to start feeding the subsequent document P. Then, when the conveyance of the final document P is completed, the document P is detected by the paper discharge sensor 46.
When the rear end is detected, the driving of the main motor 33, the reverse drive motor 47, and the AC power supply 43 is stopped, as shown in FIG.

As described above, in this embodiment, the document P conveyed to the reading position and having been read is separated from the contact glass 4 by the pick-up solenoid 41 of the endless belt 36 to which the unequal electric field is applied. , After picking up the document P from the contact glass 4, the switching claw 19
The delivery path is switched to the delivery unit 16 side by the delivery unit 11a.
When a double-sided original is read, the original P whose one side has been read is scooped up above the contact glass 4 by the endless belt 36 and the scooping solenoid 41, and then switched back by the switching claw 19.
After switching the transport path to the 18 side and transporting to the switchback passage 17, it is switched back and returned to the endless belt 36 via the guide plates 39b and 39a, and the endless belt 36 again reads the contact glass 4 at the reading position. Have been sent back to.

For this reason, the document P is scooped up and discharged.
Since the paper can be discharged to the 16 or switchback means 18, the structure between the endless belt 36 and the paper discharge means 16 and the switchback means 18 can be simplified to reduce the space of the conveyance path of the document P. You can Further, unlike the conventional case, since the original P is not discharged to the discharge tray on the side of the image reading apparatus main body, the length in the longitudinal direction of the automatic document feeder 3 can be shortened and the space is small. The double-sided original can be conveyed with. As a result, the automatic document feeder 3 can be downsized, and
The cost can be reduced.

Further, the original P returned from the switchback passage 17 by the switchback means 18 is fed to the endless belt.
Since the guide plates 39a and 39b for conveying toward the 36 are provided, the switched back document P can be returned to the endless belt 36 through a short conveying path, and the conveying time can be shortened. Further, a registration sensor 28 for detecting the front and rear ends of the original is provided upstream of the conveying means 15 in the original conveying direction, and when the original is conveyed toward the switchback means 18 by the endless belt 36 during the conveyance of a double-sided original. The scooping solenoid 41 scoops the document P from the contact glass 4 based on the document front edge detection information from the registration sensor 28, and the endless belt 36 discharges the document P returned from the switchback device 18. When transporting toward 16, the registration sensor 28
Since the control means 34 for picking up the document P from the contact glass 4 by the scooping solenoid 41 based on the detection information of the trailing edge of the document P from FIG. It is possible to scoop up from the contact glass 4, prevent the number of the registration sensors 28 installed from increasing, and increase the cost thereof, so that the automatic document feeder 3 can be made even lower in cost. Further, since the original P is scooped from the contact glass 4 when the double-sided original is conveyed based on the detection information of the front and rear edges of the original P, the double-sided original is surely contacted with the contact glass 4 regardless of the size of the double-sided original.
You can scoop it up.

Further, the conveying means 15 is composed of an endless belt 36,
The endless belt 36 is composed of a belt driving roller 37 and a stretching roller 38, which are provided separately on the upstream side and the downstream side in the document conveying direction, and suspend the endless belt 36. Since the tension roller 38 is composed of a scooping solenoid 41 for moving the contact roller 4 close to and away from the contact glass 4 with the belt driving roller 37 as a fulcrum, an electrode roller 42 for applying an AC voltage to the endless belt 36, and an AC power source 43. The flat surface of the endless belt 36 allows the original P to be sucked onto the belt 36, the adhesion of the original P is improved, and the original P can be picked up from the contact glass 4 and conveyed in a stable state.

Further, when the original P is picked up from the contact glass 4, the stretching roller 38 is separated from the contact glass 4 with the belt driving roller 37 as a fulcrum, so this separating operation (rotation of the endless belt 36) is performed. Operation) to prevent the conveyance speed of the endless belt 36 from changing,
The document P can be read with high accuracy by the reading unit 2 of the scanner device 1.

As shown in FIG. 9, when a large-sized document P is reversed and returned from the switchback passage 17 to the reading position, the front end of the document P is pressed by the pressure roller 45 and the driving roller 44.
The trailing edge of the document P is pinched by the pressure roller 49 and the drive roller 44.
May be pinched by. In this embodiment, the contact pressure between the pressure roller 49 and the drive roller 44 is set to be smaller than the contact pressure between the pressure roller 45 and the drive roller 44. The original P by the drive roller 44
Can be firmly pinched, and can be pinched with a relatively small force by the pressure roller 49 and the driving roller 44, and the load when the document P is conveyed can be reduced.
As a result, it is possible to sufficiently protect the document P and improve the transport performance.

10 to 12 are views showing a second embodiment of the automatic document feeder according to the invention of claim 1 or 2, and in this embodiment, the pick-up solenoid 41 controls the switching of the document feed path. Since an example is shown and the configuration is the same as that of the above-described embodiment, only the method of carrying the same will be described. In the above-described embodiment, the document P picked up by the endless belt 36 is conveyed only by the switching claw 19 between the drive roller 44 and the pressure roller 45 and between the drive roller 44 and the pressure roller 49. Although the direction is switched, in the present embodiment, FIG. 10 (c), FIG. 11 (a) (b), FIG. 12 (b)
, The position of the stretch roller 38 is finely controlled by the scooping solenoid 41, and between the drive roller 44 and the pressure roller 45 and between the drive roller 44 and the pressure roller 49 in the respective conveying directions. By connecting the endless belt 36 to the stretch roller 38 side, the conveyance path of the document P is switched. In addition to this control, the conveyance path is switched by the switching claw 19, so that the document P is different from that in the above embodiment.
The transfer route can be switched with higher accuracy. Further, by performing the control as in this embodiment,
The switching claw 19 may be omitted.

[0061]

According to the first aspect of the present invention, since the original can be picked up and discharged to the discharging means or the switchback means, the structure between the conveying means and the discharging means and the switchback means is provided. Can be simplified to reduce the space of the document conveying path, and since the document is not discharged to the discharge tray on the side of the image reading apparatus body as in the conventional case, the automatic document conveying device The length in the longitudinal direction can be shortened, and a double-sided original can be conveyed in a small space. As a result, the automatic document feeder can be downsized and the cost thereof can be reduced. Further, since the document returned from the switchback path by the switchback means is directly returned to the endless belt via the transport path, the switched-back document can be returned in the short transport path, and the transport time can be shortened. It can be shortened.

Further, the original can be scooped from the contact glass when the double-sided original is conveyed based on the detection information from one detecting means, and it is possible to prevent an increase in the number of the detecting means installed and an increase in the cost thereof. The automatic document feeder can be made even lower in cost. Furthermore, since the original is scooped from the contact glass when the double-sided original is conveyed based on the detection information of the front and rear edges of the original, the double-sided original can be reliably scooped from the contact glass regardless of the size of the double-sided original.

According to the second aspect of the present invention, since the original can be sucked by the flat surface of the endless belt, the original can be picked up from the contact glass in a stable state by improving the adhesion of the original. Can be transported. Further, when the original is scooped up from the contact glass, the roller on the upstream side in the conveying direction is used as a fulcrum to separate the roller on the downstream side in the conveying direction from the contact glass, so that the separating operation (rotating operation of the endless belt) is performed.
Thus, it is possible to prevent the transport speed of the endless belt from changing, and the document can be read with high accuracy by the reading unit of the image forming apparatus.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of an automatic document feeder according to the present invention.

FIG. 2 is a state diagram of an automatic document feeder when one document is read while stationary on a contact glass.

FIG. 3 is a block diagram of a control system of the automatic document feeder.

FIG. 4A is a diagram showing a configuration of an applying member that applies an AC voltage to the endless belt, and FIG. 4B shows an uneven electric field formed on the endless belt and a document feeding state by the electric field. FIG.

5A to 5C are diagrams showing a document transport state by an automatic document transport device.

6A to 6C are diagrams showing a document conveyance state following FIG.

7A and 7B are diagrams showing a document conveyance state following FIG.

FIG. 8 is a timing chart when a double-sided original is conveyed.

FIG. 9 is a diagram showing a state in which the front and rear ends of a document are nipped by a drive roller and a pressure roller. It

FIG. 10 is a configuration diagram of a second embodiment of the automatic document feeder according to the invention of claim 1 or 2, and FIGS. 10A to 10C are diagrams showing a document feeding state by the automatic document feeder. Is.

11 (a) and 11 (b) are diagrams showing a document conveyance state following FIG.

12 (a) and 12 (b) are diagrams showing a document conveyance state following FIG. 11.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Scanner device (original reading device) 3 Automatic document feeder 4 Contact glass 5 Light source (reading means) 6-8 Mirror (reading means) 9 Lens (reading means) 10 Imaging element (reading means) 11 Presser cover 12 Original tray ( Document placing table) 13 Separation / feeding means 14 Scooping means 15 Conveying means 16 Paper ejecting means 17 Switchback passage 18 Switchback means 19 Switching claw (switching means) 28 Registration sensor (front and rear edge detection sensor) 36 Endless belt (conveyance) 37) Belt driving roller (belt conveying roller, conveying means) 38 Stretching roller (belt conveying roller, conveying means) 39a, 39b Guide plate (conveying path) 41 Scooping solenoid (proximity separating member) 42 Electrode roller (applying member) 43 AC power supply (application member) 51 Switching claw solenoid (switching means)

Claims (2)

[Claims] 1. A reading unit configured to move when reading a document that is stationary on the contact glass and to stop at a predetermined reading position when reading a document conveyed on the contact glass. In an automatic document feeder provided in an image reading device, a pressing cover for pressing an original placed on a contact glass against the contact glass, and an original provided above the pressing cover and capable of holding a plurality of originals The placing table and the document feed port are formed on the edge of the contact glass.
A bundle of originals placed on the original placing table is fed from the paper feed port, originals are separated from the original bundle one by one, and the separated originals are inverted and conveyed toward a predetermined reading position. Separation / conveyance means, conveyance means having an endless belt for conveying a document conveyed toward a predetermined reading position by the separation / conveyance means to the reading position, and an unequal electric field formed on the endless belt The endless belt sucks a document and scoops it up from the contact glass, a sheet ejecting unit that ejects the document scooped by the scooping unit onto the presser cover, and a device provided adjacent to the sheet ejecting unit. The switchback means for transporting the document picked up by the scooping means to the switchback path and then returning it to the endless belt via the transport path, and the switchbar. Switching means provided on the upstream side of the document feeding direction of the feeding means and the paper discharging means, for switching the feeding direction so as to carry the document picked up by the scooping means to either one of the switchback means and the paper discharging means; A detection means which is provided on the upstream side of the means for detecting the front and rear edges of the original; and when the double-sided original is conveyed, the conveying means conveys the original toward the switchback means. When the original returned from the switchback means is conveyed to the paper discharge means by the conveying means while controlling the scooping means based on the front end detection information of the original, the original is returned from the switchback means. A control hand that controls the scooping means based on the rear edge detection information of the document to scoop the document from the contact glass. When the automatic document feeder, characterized in that it consists of. 2. The conveying means includes a pair of belt conveying rollers which are provided on the upstream side and the downstream side of the endless belt in the conveying direction of the original so as to be separated from each other, and which suspends the endless belt. , A proximity separating member for moving the belt carrying roller downstream of the original carrying direction in the original carrying direction toward and away from the contact glass with the belt carrying roller upstream of the carrying direction as a fulcrum, and a voltage alternating to the endless belt. The automatic document feeder according to claim 1, comprising an applying member for applying.