JP2002094743A - Double-side original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-side original reader that uses two light sources used also to read a double-side original, when reading a one-side original to quicken the reading of the one-side original. SOLUTION: At double-side reading, the double-side original is carried through a 2nd read carrier path 42c from a 1st read carrier path 42b; a 1st light source 350 has a light irradiated to a 1st read section 3b to read one side of the original; a 2nd light source 450 has a light irradiated to a 2nd read section 3c, the light is reflected in a slide white board 38, to read the other side of the original. At one-side reading, the one-side original is carried through a one-side discharge carrier path 42d from the 1st read carrier path 42b; the slide white board 38 is made to move; and the light from the 2nd light source 450 passes through the 2nd read carrier path 42c, is reflected in a reflection board 37 and emitted to the 1st read section 3b together with the light from the 1st light source 350.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided original reading apparatus used in a copying machine, a printer, a facsimile apparatus, a scanner, etc., which can read both sides of a double-sided original and an image of a single-sided original.

[0002]

2. Description of the Related Art In general, as a document reading apparatus for reading image information from a document on which information is recorded, a document stationary type for reading a document stationary on a transparent document placing table (contact glass) and a transparent conveyance guide ( Contact glass)
A document traveling type in which a document is read while the document is traveling thereon is known.

In a document reading apparatus of the document traveling type, for example, as described in Japanese Patent Application Laid-Open No. 9-284480, reading optical systems are arranged on both sides of a document conveying path, and both sides of the document are read. There is known a double-sided document reading apparatus capable of simultaneously reading documents. Such a two-sided document reading apparatus can read a two-sided document without reversing the document, and is suitable for higher-speed reading.

[0004]

The above two-sided document reading apparatus uses two optical systems arranged corresponding to both sides of a document. However, in the case of both sides, both optical systems are used. do not become. However, since one of the optical systems is not used for reading a one-sided original, it cannot be said that the optical system is fully utilized.

In view of the above, the present invention utilizes the two optical systems not only when reading a two-sided original but also when reading a one-sided original, and can read a one-sided original at a high speed. The purpose is to provide the device.

[0006]

According to a first aspect of the present invention, a first reading unit having a first reading unit for reading this surface and a first light source for irradiating the first reading unit is provided on one side of the document. A second reading unit for reading this surface and a second light source for irradiating the second reading unit on the other surface of the original
A reading unit is provided, and a light distribution unit is provided so as to guide the light of the second light source to the first reading unit when reading a one-sided document.

[0007] Thus, the two light sources of the two reading means can be used not only when reading a double-sided document but also when reading a single-sided document, and the illuminance of the document surface at the time of single-sided reading is increased. The document conveyance speed can be made higher than the document conveyance speed at the time of double-sided reading, and the reading speed can be increased.

Here, the second light source is positioned on the opposite side of the first light source with respect to the document conveyance path during double-sided reading, and is positioned on the same side as the first light source with respect to the conveyance path during single-sided reading. If the positional relationship between the second light source and the transport path is changed, light from the second light source can be guided to the first reading unit when reading a one-sided document.

That is, if there is a first transport path for transporting a document when performing double-sided reading and a second transport path for transporting a document when performing single-sided reading, the second transport path is:
After passing through the first reading unit, it is formed so as not to pass through the second reading unit. Then, an optical path from the second light source to the first reading unit is formed so as to cross the first transport path. Therefore, the optical path is interrupted by the document conveyed in the first conveying path, but the second conveying path does not cross the optical path.
At the time of single-sided reading, light from the second light source is guided to the first reading unit.
Therefore, in this case, the second light source can be positioned on the same side as the first light source by switching the document conveyance path, and the mechanism for switching the conveyance path becomes the light distribution unit.

As described above, since the conveyance path for one-sided reading is provided so as not to block the optical path for guiding the light from the second light source to the first reading section, the optical path is not blocked by the document that has been read. Therefore, the illuminance of the original on reading one side does not fluctuate, and stable image reading can be performed. Also, there is no need to separate the first reading unit and the second reading unit,
It is possible to reduce the size of the apparatus, and furthermore, it is not necessary to provide an interval between the conveyed documents so as not to block the optical path, the interval between the documents can be reduced, and the reading time of a large number of documents can be reduced. .

At this time, a light blocking member for blocking the optical path may be movably provided as a light distribution means. The light blocking member is moved to block the light path when reading both sides, and the light blocking member is separated from the light path when reading one side. Move and secure the optical path. Since this optical path crosses the second transport path, the light of the second light source passes through the second transport path. However, the light is blocked by providing the light blocking member, and does not reach the first reading unit.
That is, two optical paths are switched. Therefore, it is possible to prevent the light of the second light source from adversely affecting the reading by the first reading unit at the time of double-side reading, so that the illuminance does not fluctuate in the first reading unit and the read image does not need to be corrected.

Here, in order for the optical path to cross the second transport path, the second transport path must be formed by a transparent member. This may make it difficult to read a document such as a thin paper document whose reflected light amount is reduced as a whole. Therefore, if a reference white plate for performing shading in the second reading unit is used as a light shielding member, light from the second light source can be reflected, and sufficient light can be reflected even when reading a thin paper document whose reflected light amount is reduced. Light quantity is obtained, and it is not necessary to correct the read image. If the reference white plate is disposed outside the conveyance path, the reference white plate is not stained by the document, and the original shading can be appropriately performed.

In the above description, the positional relationship between the second light source and the transport path is changed by switching the transport path. However, the position of the second light source with respect to the transport path may be changed. That is, the second light source is movable, and at the time of double-side reading, the second light source is located on the opposite side of the first light source with respect to the conveyance path,
At the time of one-sided reading, the second light source is moved to be located on the same side as the first light source, and the first reading unit is directly irradiated by the two light sources. In this case, a mechanism for moving the second light source is a light distribution unit. Alternatively, the exit of the light may be moved without moving the second light source itself. That is, the second
A light guide such as an optical fiber for guiding light from the light source is provided, and an exit of the light guide is provided on the same side as the first light source. At the time of double-side reading, the light guide is moved so that the light of the second light source does not enter the light guide, and the second reading unit is directly irradiated. At the time of one-sided reading, the light guide is moved so that the light of the second light source is incident, and the light guided by the light guide is emitted to the first reading unit. In this case, the light guide serves as light distribution means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall configuration of an image forming apparatus provided with a double-sided document reading apparatus according to an embodiment of the present invention.
FIG. 2 shows this functional block diagram. This image forming apparatus is mainly composed of an image forming apparatus main body 1 and a printing device 2 and a double-sided document reading device 3 provided therein.

The document reading device 3 includes a stationary document reading unit 3a, a first traveling document reading unit 3b, and a second traveling document reading unit 3c. The stationary original reading section 3a is a reading section for reading an original that is not to be automatically fed, such as a book original or a pasted original placed on the first contact glass 31 made of transparent glass. The first traveling document reading section 3b is a reading section for reading the document automatically fed on the second contact glass 32 made of transparent glass while traveling.
The second traveling document reading section 3c is a reading section for reading the document automatically fed between the third contact glass 33 and the fourth contact glass 47 made of transparent glass while traveling.

The image of the original read by the stationary original reading section 3a, the first traveling original reading section 3b, and the second traveling original reading section 3c is sent to an image processing section 83, which will be described later, and after being subjected to various processes. Is temporarily stored in the image memory 81, read out from the image memory in response to a print command, and formed as an image on a sheet by the printing device 2. The document reading device 3 will be described later in detail.

Next, the printing device 2 will be described. The printing device 2 includes an electrophotographic processing unit 20 for forming an image, a laser writing unit 21 (hereinafter referred to as an LSU (Laser
Scanning Unit), a paper transport unit 22 and a fixing device 23.

The LSU 21 includes a semiconductor laser light source 210 that emits a laser beam in accordance with image data read by the document reading device 3, a polygon mirror 211 that deflects the laser beam at a constant angular speed, and a laser beam deflected at a constant angular speed. An fθ lens 212 that corrects the image so as to be scanned at a constant speed on the drum-shaped photoreceptor 200 constituting the photographic process unit 20;
A folding mirror 213 and the like for turning the laser light passing through the fθ lens 212 toward the photoconductor 200 are provided.

Then, as shown in FIG. 2, the LSU 21 converts the image data in the image memory 81 transferred via the system bus into a blinking signal of the semiconductor laser (LD) 210 corresponding to the image data by the modulator 215. The light is modulated, the semiconductor laser 210 is turned on and off, and the photosensitive member 200 is scanned. Further, in order to determine a timing at which a laser beam scanning on the photoconductor 200 outputs a signal corresponding to image data from the modulation unit 215 so that a writing start position becomes constant for each scan, the synchronization sensor 216 is used. Is provided. The synchronization sensor 216 detects a light beam of the light beam that scans other than the image area on the photoconductor 200 and sends a signal for determining the timing to the system controller 80. In response to this signal, the system controller 80
Sends the image data in the image memory 81 to the modulation unit 215.

The electrophotographic process unit 20 includes a photosensitive member 200
Around the charger 201, the developing device 202, the transfer device 203,
A peeling device 204, a cleaning device 205, and a static eliminator 206 are provided. The charger 201 uniformly charges the surface of the photoconductor 200 to a predetermined potential. Next, the semiconductor laser 201 of the LSU 21 scans the surface of the uniformly charged photoconductor 200 in accordance with the image data to form an electrostatic latent image.
The developing device 202 visualizes the electrostatic latent image formed by the scanning of the LSU 21 into a toner image. Next, the transfer device 203
Transfers the toner image carried on the surface of the photoreceptor 200 to the sheet sent by the sheet conveying unit 22. Exfoliator 20
4 neutralizes the electric charge of the sheet adsorbed on the photoconductor 200 and peels the sheet from the photoconductor 200. Cleaning device 2
A step 05 removes the toner remaining on the surface of the photoconductor 200 after the transfer from the surface of the photoconductor 200. Finally, the static eliminator 206
Irradiates the surface of the photoconductor 200 to reduce the charge on the surface of the photoconductor 200 to a uniform and small value. By repeating such a process, an image is transferred onto a sheet.

Here, the process unit controller 207
Receives the control signal from the system controller 80 via the system bus and controls the electrophotographic processing unit 20.

On the other hand, the paper transport section 22
0a, a sheet storage unit such as a manual tray 220b, a separating and feeding unit 221, a synchronous roller 222, a transport belt 223,
A discharge roller 224, a switchback unit 225, an automatic double-sided sheet feeder 226, a conveyance path and a conveyance unit provided between these units, and a drive source and a drive transmission unit (not shown) for driving these units. Have been.

The paper stored in the paper storage means is separated by a separating and feeding means 221 disposed downstream in the paper transport direction.
The sheets are separated one by one and sent out from the sheet storage means to the transport path. Next, the sheet is fed to the sheet storage unit and the synchronous roller 222.
The photoconductor 200 and the transfer device 203 are guided to a synchronous roller 222 disposed immediately before a position where the photoconductor 200 and the transfer device 203 face each other (hereinafter, referred to as a transfer position). The synchronization roller 222 conveys the sheet to the transfer position in synchronization with the toner image on the photoconductor 200. The sheet sent out by the synchronous roller 222 adsorbs and carries the toner image on the photoreceptor 200 by the transfer device 203, and then is sent out toward the fixing device 23 by the transport belt 223. The sheet that has passed through the fixing device 23 is sent out toward the post-processing device 6 by the discharge roller 224 in the one-sided printing mode. In the double-sided printing mode, the sheet after single-sided printing is switched back by the switchback means 225 and sent to the automatic double-sided paper feeder 226 to be stored therein. The paper accommodated in the automatic duplex paper feeder 226 is separated from the automatic duplex paper feeder 226 one by one and sent out toward the synchronous roller 222 corresponding to the duplex printing, and the toner image is carried on the opposite surface. Then, the sheet passes through the fixing device 23 again and is sent out to the post-processing device 6 in the same manner as in the single-sided mode. The lower surface of the image forming apparatus main body 1 has a receiving opening 22 for receiving paper from the multi-stage paper feeding desk 5.
7, a transport path and transport means are provided.

A paper transport controller 228 for controlling the transport of the paper receives a control signal from the system controller 80 via the system bus, controls the paper transport 22 and outputs a detection signal of a jam or the like to the system bus. To the system controller 80 via.

The fixing device 23 includes a pair of fixing rollers 23.
0, a heating source 231, a temperature sensor 232, a peeling claw 233, and the like. The temperature and pressure are applied to the toner carried on the passing paper to fuse it to the paper. Peeled off and sent out. Further, the fixing device controller 234 includes the system controller 8.
0 via the system bus
It controls the fixing device 23 and sends the value detected by the temperature sensor 232 to the system controller 80 via the system bus.

Further, a multi-stage paper feed desk 5 and a post-processing device 6 which are optional devices are provided. The multi-stage paper feed desk 5 is arranged below the image forming apparatus main body 1 and has a plurality of paper trays 50 stacked. The sheets are separated one by one from one of the paper trays 50 by a separation feeding unit 51 in response to an image forming instruction, and are provided on a lower surface of the image forming apparatus main body 1 through a delivery opening 52 on an upper surface of the multi-stage paper feeding desk 5. The sheet is sent out to the receiving opening 227. Then, the multi-stage paper feeding desk controller 53 receives a control signal from the system controller 80 via the system bus, controls paper feeding from the multi-stage paper feeding desk 5, and outputs signals such as presence / absence of paper, paper size, and jam. To the system controller 80 via the system bus.

The post-processing device 6 is disposed on the discharge roller 224 side of the image forming apparatus main body 1, receives the paper discharged from the image forming apparatus main body 1 by the carry-in roller 61, and switches the conveyance path by the gate 62. In the copy mode, the sheet is discharged to the copy mode discharge tray 65 by the discharge roller 63, and in the printer mode, the sheet is discharged to the printer mode discharge tray 66 by the discharge roller 64. The post-processing device 6 is configured to sort and print out the printed matter in the printer mode and the printed matter in the copy mode, and may also perform post-processing such as stapling and punching. Further, as shown in FIG. 2, the post-processing controller 67 receives a control signal from the system controller 80 via a system bus, and
, And signals such as the presence or absence of free space in the discharge trays 65 and 66 and a jam or the like are sent to the system controller 80 via the system bus.

A system controller 80 provided in the image forming apparatus main body 1 includes a process unit controller 2 for controlling the operation unit 70, the image memory 81, the LSU 21, and the electrophotographic process unit 20 via a system bus.
07, a paper transport unit controller 228 for controlling the paper transport unit 22, a fixing device controller 234 for controlling the fixing device 23, a power supply substrate controller 71 for controlling the power supply substrate, and other components of the printing device 2, and the document reading device 3.
A signal is transmitted and received between the reading control unit 82, the post-processing controller 67, and the multi-stage paper feeding desk controller 53 so that a series of operations from reading of a document to discharging of a printed material are appropriately performed. The entire image forming system including the forming apparatus, the multi-stage paper feeding desk 5 and the post-processing apparatus 6 is controlled.

Next, the original reading apparatus 3 of the present embodiment is shown in FIG.
It will be described in detail based on. The document reading device 3 includes a main body unit 30 and an opening unit 40, and performs one-side reading and both-side reading of a document. A first contact glass 31, a second contact glass 32, a document reference plate 34, and a transport guide 36 are arranged on the upper surface of the main body 30 in order from the right side of FIG.
And a third contact glass 33.

An index indicating the size of the original and the mounting direction is printed on the original reference plate 34, and the original can be easily placed on the stationary original reading section 3a on the first contact glass 31 according to the index. It has become. On the side of the document reference plate 34 facing the first contact glass 31, a first reference white plate used when shading the first photoelectric conversion element 356 of the first scanning system 35 (determining its own level) is performed. 34a are provided.

Inside the main body 30, a first scanning unit 35a, a second mirror 353, and a third mirror 354 for integrally supporting a first light source 350 and a first mirror 351 for irradiating an original are integrally formed. And a first scanning unit (first reading unit) 35 including a second scanning unit 35b, a first imaging lens 355, and a first photoelectric conversion element 356 (CCD). The first scanning unit 35a and the second scanning unit 35b include the first scanning unit 35a
The second scanning unit 35b is wound around a wire (not shown) so as to move in the same direction at half speed, and is driven by a first reading scanning system driving motor 93 which is a stepping motor. When the first reading / scanning system driving motor 93 rotates forward, it moves rightward in FIG. 1, and when the first reading / scanning system driving motor 93 rotates reversely, it moves leftward.

The first scanning system 35 is used both when reading a still original and when reading a traveling original. At the time of reading a stationary document, the first scanning unit 35a moves from the position a2 facing the document reference plate 34 to the position a3 along the first contact glass 31 to transfer the document resting on the first contact glass 31. Read and scan. When reading the traveling original, the first scanning unit 35a is stopped at the position a1 facing the first traveling original reading unit 3b.

The first light source substrate 84 that controls the first light source 350 turns on or off the first light source 350 based on a signal from the reading control unit 82. The first reading scanning system driving motor control board 85 controls the first reading scanning system driving motor 93 based on the signal of the reading control unit 82 to reciprocate the first scanning unit 35a and the second scanning unit 35b.

The first reading scanning system position sensor group 86
The scanning unit 35a is arranged at a position facing the first traveling original reading unit 3b and at a position where the first reference white plate 34a can be read (home position of the first scanning unit 35a), and the first scanning unit 35a is located at this position. When it comes, a reference position signal is output to the reading control unit 82.

The reading control unit 82 calculates the position of the first scanning unit 35a based on the reference position signal of the first reading scanning system position sensor group 86 and the number of steps of the first reading scanning system driving motor 93, First reading scanning system drive motor control board 85
The first scanning drive system drive motor 93 is controlled to rotate in the forward and reverse directions through the first scanning unit 35 a and the second scanning unit 3.
5b is reciprocated.

The second scanning unit 35b is at the position b3 when the first scanning unit 35a is at the position a3, and is at the position b1 when the first scanning unit 35a is at the position a1.

In the first scanning unit 35a, light is emitted from the first light source 350 toward the original during the scanning, and the reflected light from the original is transmitted to the second mirror 352 via the first mirror 352.
The light is reflected toward the second mirror 353 of the scanning unit 35b. In the second scanning unit 35b, the first mirror 35
The reflected light from the second mirror 353 and the third mirror 3
The light is reflected toward the first imaging lens 355 through the light-receiving element 54. The first imaging lens 355 forms an image of the light reflected from the third mirror 354 on the light receiving surface of the first photoelectric conversion element 356.
The first photoelectric conversion element 356 converts the received light into an electric image signal according to the intensity of the received light and outputs the electric image signal.

On the lower surface side of the third contact glass 33, a slide white plate 38 also serving as a reference white plate of the second reading scanning system 45 is arranged. Below the slide white plate 38, a reflection plate 37 is provided between the slide white plate 38 and the second scanning unit 35b.
Is arranged.

The opening 40 of the document reading device 3
The document reading device 3 is pivoted upward about a hinge (not shown) provided between the document reading device 3 and the
Is configured to be open on the near side. Open part 4
On the right side of 0, an OC mat 46 whose first contact glass 31 side is white is provided so as to contact the first contact glass 31 when the opening 40 is closed. The sheet-shaped original placed on the stationary original reading unit 3a is
The mat 46 presses the first contact glass 31 into close contact therewith.

A double-sided automatic document feeder 42 is disposed on the left side of the opening section 40. The document is set from a document set tray 41 on which a document is set to a first traveling document reading section 3b and a second traveling document reading section 3c. Or the original is conveyed to the first traveling original reading section 3b, and the original is discharged to the single-sided discharge tray 43 or the double-sided discharge tray 44. On the left side of the opening 40, a second reading scanning system (second reading means) is provided.
45 is provided to scan and scan a document traveling on the second traveling document reading unit 3c.

In the automatic document feeder 42 for both sides, the carry-in path 4 between the separation feeding means 420 and the pair of aligning rollers 421 is provided.
2a, alignment roller pair 421 and second document transport roller 424
The first traveling conveyance path 42b provided with the first traveling original reading section 3b provided between the first traveling original reading section 3b and the second traveling original reading section 3c provided between the second original conveying roller 424 and the second discharge roller 427. A second reading conveyance path 42c and a one-sided discharge path 42d branched from the second reading conveyance path 42c and reaching the first discharge roller 426 are formed.

Here, the configuration and operation of each unit of the automatic document feeder 42 for both sides will be described. Separation feeding means 420
Is composed of a feeding unit 420a and a separation feeding unit 420b.
The document set on the sheet 1 is called into the separation feeding section 420b, separated by the separation feeding section 420b one by one, and conveyed toward the pair of alignment rollers 421.

The separating / feeding means 420 has an electromagnetic clutch 95 on a drive shaft thereof, and is connected to and disconnected from a drive system for transmitting a driving force from a drive motor 94 of the automatic document feeder 42 for two-sided printing. It can be switched to connection. The aligning roller pair 421 has an electromagnetic clutch 92 on its drive shaft, and switches between a connection and a non-connection to a drive system that transmits a driving force from a drive motor 94 of the automatic document feeder 42 for both sides. It is possible. The alignment roller pair 421 is stopped until the leading edge of the document fed from the separation feeding unit 420 is along the nip portion of the alignment roller pair 421, and is directed downstream after the leading edge of the document is along the nip portion. By starting the conveyance, the document is prevented from being conveyed obliquely. When the leading edge of the document is made to follow the nip portion, the separation feeding unit 420 feeds the document,
As a result, a predetermined flexure is formed, so that the leading edge of the document follows the nip.

The first document conveying roller 422 is disposed at the middle of the first reading and conveying path 42b, and lightly contacts the second contact glass 32 to convey the document. The area where the first document transport roller 422 contacts the second contact glass 32 and its surroundings constitute the first traveling document reading section 3b. The peripheral surface of the first document transport roller 422 is white, and when reading and scanning a document traveling on the first traveling document reading unit 3b, the reflected light from the document is not reduced when reading a thin paper document. is there. For this reason, the first document conveying roller 422 has a peripheral surface of the roller covered with a film body, and includes a porous thin elastic layer such as a sponge below the film body. In addition, the coefficient of friction between the film body and the second contact glass 32 is in the position. As a result, the first document conveying roller 422 comes into light contact with the second contact glass 32 to convey the document, and the nip width between the first document conveying roller 422 and the second contact glass 32 is increased. The original can be read properly.

The second document feed roller 424 makes light contact with the left end of the second contact glass 32, and feeds the document after passing through the first traveling document reading section 3b downstream. By clamping the document between the second document transport roller 424 and the second contact glass 32, the influence of the downstream transport affects the portion of the traveling document in the first traveling document reading unit 3b. In addition, the effect of the conveyance by the first document conveyance roller 422 is prevented from affecting the portion of the running document in the second traveling document reading unit 3c, so that the read image data is not affected. ing. The structure of the second document conveying roller 424 is also similar to that of the first document conveying roller 422.
A film body is provided on the peripheral surface, and a thin elastic layer is provided below the film body. The coefficient of friction between the film body and the second contact glass 32 is also set in the same manner as the first document conveying roller 422.

The second reading conveyance path 42c and the one-side discharge path 42d
In the one-sided reading mode, the branching gate 425 assumes the posture indicated by the broken line in FIG. 3 and guides the document passing through the first reading / conveying path 42b to the one-sided discharging path 42d. At the time of the reading mode, the original is in the posture indicated by the solid line, and
It is led to the reading conveyance path 42c. When the branch gate 425 is rotated clockwise around the rotation fulcrum by turning on the gate driving solenoid 91 and assumes a posture indicated by a broken line, the tip of the branch gate 425 enters a concave portion formed in the transport guide 36. It is configured as follows. Also, the branch gate 425
When the solenoid 91 is turned off, the solenoid 91 rotates counterclockwise around the rotation fulcrum by the action of a return spring (not shown) to assume a posture indicated by a solid line, and stops.

The first discharge roller 426 is connected to the one-side discharge path 42.
d of the single-sided output tray 43 with the front and back sides reversed when the original conveyed in the direction d is placed on the original set tray 41.
To be discharged.

The second reading conveyance path 42c is formed between the third contact glass 33 and the fourth contact glass 47 made of transparent glass disposed above the third contact glass 33. And the third
A region where the slide white plate 38 disposed on the lower surface of the contact glass 33 faces the second traveling document reading unit 3c.

The second discharge roller 427 is integrally and rotatably provided in the opening 40, and is provided in the second reading conveyance path 4.
The original that has passed through 2c is discharged to the duplex discharge tray 44. The two-sided discharge tray 44 is provided integrally with the opening 40,
Documents discharged from the second discharge roller 427 are stacked.

The original detection sensors s1, s2, s3
Are disposed on the upstream side in the transport direction of the pair of alignment rollers 421, on the downstream side in the transport direction of the first discharge roller 426, and on the downstream side in the transport direction of the second discharge roller 427, respectively. These document detection sensors 89 determine the position of the document by the reading control unit 8.
2 to the system controller 80.

The operation of each section of the automatic document feeder 42 for both sides will be described below. The drive motor control board 90 of the double-sided automatic document feeder 42 controls the drive motor 94, which is a stepping motor, on and off in response to a signal from the reading control unit 82 to drive the drive system of the double-sided automatic document feeder 42. As a result, the separation feeding unit 420, the pair of alignment rollers 421, the first document transport roller 422, the second document transport roller 424, the first discharge roller 426, and the second discharge roller 4
The driving force is transmitted to 27 and other transport rollers. The rotation speed of the drive motor 94 is made variable by a pulse rate from the drive motor control board 90.

The document detection sensors s1, s2, and s3 output a document presence / absence signal to the reading control unit 82 when the traveling document reaches the sensor position. On the other hand, the reading control unit 82 calculates whether or not the document is being conveyed at an appropriate timing by using a timer with a document presence / absence signal from the document detection sensors s1, s2, and s3, and determines whether a conveyance failure has occurred. In such a case, a signal indicating occurrence of a jam or the like is output to the system controller 80 via the system bus.

The electromagnetic clutch 92 is turned on and off in response to a signal from the reading control unit 82, and switches the connection and disconnection of the alignment roller 421 to or from the drive system of the automatic document feeder 42 for duplex printing, and stops the alignment roller 421. Or rotate.

Next, the second reading scanning system 45 will be described. The second reading scanning system 45 is provided in the opening unit 40, and is a reading scanning system for reading a document traveling on the second traveling document reading unit 3c. The second reading scanning system 45 irradiates the second light source 450 for irradiating the upper surface of the document traveling on the second traveling document reading unit 3c, and irradiates the light of the second light source 450 toward the second traveling document reading unit 3c. Reflection member 4 for performing
51, a reflection mirror 45 for guiding the reflected light from the original traveling on the second traveling original reading unit 3c to the second imaging lens 458
3,453,456,457, the reflected light from the document imaged by the second imaging lens 458 is received by the light receiving surface,
A second photoelectric conversion element (CCD) 459 that converts and outputs an electric image signal according to the intensity of the received light, and shades (white) the electric image signal output from the second photoelectric conversion element 459. And a slide white plate 38 to be read as the level of the white part when making the determination of the part level. The slide white plate 38 is provided on the main body 30 side so as to be slidable in the left-right direction.

The second light source substrate 88 for controlling the second light source 450 turns on or off the second light source 450 based on a signal from the reading control unit 82. The slide white plate drive solenoid 87 moves the slide white plate 38 between the position indicated by the solid line and the position indicated by the broken line in FIG. That is, in the double-side reading mode, by turning off the slide white plate drive solenoid 87 and keeping the slide white plate 38 at the position indicated by the solid line, shading can be performed on the electrical image signal output from the second photoelectric conversion element 459. And intercept the light of the second light source 450 passing through the fourth contact glass 47 and the third contact glass 33 between the original traveling on the second traveling original reading unit 3c and the next original.
It does not reach the reflection plate 37 and reach the first traveling original reading unit 3b. Further, in the single-sided reading mode, the slide white plate drive solenoid 87 is turned on to set the slide white plate 38 at the position indicated by the broken line, so that the light from the second light source 450 passes through the fourth contact glass 47 and the third contact glass 33. The optical path leading to the reflection plate 37 is opened. By opening this optical path, the light of the second light source 450 is reflected by the reflection plate 37.
And reaches the first traveling original reading section 3b.

Further, in the single-sided reading mode, the reading control section 82 outputs a signal indicating the single-sided reading mode to the drive motor control board 90 of the automatic document feeder 42 for both sides. When receiving the signal indicating the single-sided reading mode, the drive motor control board 90 sets the pulse rate larger than that in the double-sided reading mode, rotates the drive motor 94 at a higher speed, and conveys the document faster. .

Next, the operations of the first reading scanning system 35 and the second reading scanning system 45 in the one-side reading mode and the two-side reading mode, the operation of the two-sided automatic document feeder 42, and the electrical scanning obtained by the reading scanning. The processing of the image signal will be described.

First, the case of the double-sided reading mode will be described. In the double-sided reading mode, the first reading scanning system 35
The scanning unit 35a moves to the position a1, and the surface of the original traveling on the first traveling original reading unit 3b in the stopped state on the first contact glass 31 side, that is, the lower surface of the original is scanned by the first light source 350. Irradiate and scan for reading. Also,
The second reading and scanning system 45 irradiates and scans the surface of the document traveling on the second traveling document reading section 3c on the fourth contact glass 47 side, that is, the upper surface of the document by the second light source 450. The double-sided automatic document feeder 42 includes a branch gate 42.
5 is turned on, and the branch gate 425 is turned on.
Is set to the position indicated by the solid line in FIG. 3, and the original placed on the original set tray 41 is transferred to the loading path 42a, the first reading and conveying path 42b,
The sheet is discharged to the double-sided discharge tray 44 through the second reading conveyance path 42c.

At this time, processing of an electric image signal (hereinafter, referred to as an image signal) obtained by the reading scan is performed as follows. Image signals obtained by the reading scan from the first photoelectric conversion element 356 of the first reading scanning system 35 and the second photoelectric conversion element 459 of the second reading scanning system 45 are as follows:
After being sent to the image processing unit 83 and subjected to predetermined image processing, it is stored in the image memory 81 while being distinguished for each page via the system bus. The image processing unit 83 includes analog signal processing units 830 and 831, a selector 832, an A / D
It comprises a conversion unit 833, a shading correction unit 834, a filter processing unit 835, and a density conversion unit 836. These components of the image processing unit 83 operate under the control of the reading control unit 82.

The analog signal processing units 830 and 831 perform level conversion processing, sample hold processing, and signal amplification processing on the image signal input from the first photoelectric conversion element 356 and the image signal input from the second photoelectric conversion element 459, respectively. And outputs the result to the selector 832. By the way, the first reading scanning system 35 and the second reading scanning system 45 cannot use the same circuit because the light source light amount, the photoelectric conversion efficiency, the output signal level and the like are different. Dedicated analog signal processing units 830 and 831 are provided. This is mainly because the amount of light to irradiate the original is different between the two-sided reading mode and the one-sided reading mode.

A selector (selecting means) 832 selects one of the processed image signals input from each of the analog signal processing units 830 and 831, and selects an A / D conversion unit 833.
Output to That is, when the original is read and scanned by the first photoelectric conversion element 356, the selector 832 selects the image signal output from the analog signal
/ D conversion unit 833, and when the second photoelectric conversion element 459 is reading and scanning the original, the analog signal processing unit 8
31 selects an image signal to be output from the A / D converter 83
Output to 3.

The A / D converter 833 converts the analog image signal input from the selector 832 into a digital signal, and converts the quantized image signal into a shading corrector 834.
Output to

The shading correction section 834 performs black reproduction and white reproduction on the quantized image signal input from the A / D conversion section 833, and performs a filter processing section 835.
Output to The black reproduction means that the first photoelectric conversion element 35 is used.
6 or the dark character output of the second photoelectric conversion element 459 is sampled and stored, and the first data at the time of reading the original which is read data is read.
By subtracting from the image signal output by the photoelectric conversion element 356 or the second photoelectric conversion element 459, the effect of dark character output is eliminated. Further, white reproduction means that the image signal at the time of reading the original is normalized for each pixel based on the image signal for each pixel when the reference white plates 38 and 34a having uniform reflectances are read, and unevenness in light amount and optical components. The purpose is to correct the influence and the variation in the pixel sensitivity of each of the photoelectric conversion elements 356 and 459.

Filter processing section (filter processing means) 83
5 performs a predetermined filtering process, specifically, a spatial filtering process, on the image signal input from the shading correction unit 834 based on a coefficient that determines a filter characteristic set by the reading control unit 82. By
The "blur" of the image is restored by emphasizing the high frequency components of the image. That is, the image signals output from the photoelectric conversion elements 356 and 459 include optical components such as lenses and mirrors, the aperture aperture of the light receiving surface of each photoelectric conversion element 356 and 459, and the transfer efficiency of each photoelectric conversion element 356 and 459. And afterimages,
There is an MTF (Modulation Transfer Function) deterioration due to an integration effect due to physical scanning and uneven operation, and the filter processing unit 835 compensates for the MTF deterioration. As described above, the MTF corresponds to each photoelectric conversion element 3
56 and 459, the degree of deterioration greatly differs. Therefore, the reading control unit 82 determines the frequency of the filtering process by selecting which of the first photoelectric conversion element 356 and the second photoelectric conversion element 459 the selector 832 selectively outputs. Appropriate filter processing is performed by switching the characteristics. Further, since the deterioration of the MTF is more remarkable in the high frequency range, the filter processing unit 835 repairs “blur” by performing an enhancement process on the image signal in the high frequency range, thereby improving the image quality. ing.

Accordingly, the filter processing unit 835 determines whether the input image signal is an image signal from the first photoelectric conversion element 356 or an image signal from the second photoelectric conversion element 459, that is, the first image of the document. Contact glass 31
The filtering process is changed depending on whether the lower surface facing the first contact glass 47 is read or the lower surface facing the fourth contact glass 47 is read.

Density conversion unit (density conversion means, binarization means)
Reference numeral 836 denotes a unit for performing density conversion on the image signal filtered by the filter processing unit 835, for example, when facsimile communication is performed on the image signal, or when the printing condition is designated to be binarized. If the image signal is binarized and the printing conditions are multi-valued, such as a photographic image,
The image quality is improved by performing density conversion using a predetermined density characteristic. The density converter 836 includes a RAM controller and R
A data conversion is performed by reading a data conversion look-up table set in the RAM using the input image signal as an address, and performs a density conversion process. The image signal for which the density conversion processing has been completed is stored in the image memory 81.

Next, the operation of the first reading scanning system 35 and the second reading scanning system 45 in the one-side reading mode will be described. In the one-sided reading mode, the first scanning unit 35a of the first reading scanning system 35 stops after moving to the position a1, and scans the original traveling on the first traveling original reading unit 3b in the stopped state. At this time, the slide white plate drive solenoid 87 is turned on, and the slide white plate 38
Move to the position of the dashed line inside. Thereby, the second light source 45
The light of 0 passes through the contact glasses 33 and 47 without being blocked by the slide white plate 38 and reaches the reflection plate 37.
As a result, the light is converged and reflected to irradiate the first traveling original reading unit 3b. Therefore, since the first traveling original reading section 3b is irradiated with the light of the first light source 350 and the light of the second light source 450, the illuminance of the original surface of the original passing through the first traveling original reading section 3b increases, Even if the accumulation time of one photoelectric conversion element 356 is shortened, that is, even if the transport speed of the document is increased, it is possible to read the document properly.

In the image reading device, the photoelectric conversion element (C
When CD) is used, the relationship among the document conveyance speed, the document surface illuminance, the photoelectric conversion element sensitivity, and the light transmission efficiency of the lens system is approximately approximated by the following equation. Document conveying speed ≒ Document surface illuminance × Lens system light transmission efficiency × Photoelectric conversion element sensitivity So, if the above-mentioned document surface illumination is increased, the light transmission efficiency and photoelectric conversion element sensitivity of other lens systems will not be changed. In other words, the document conveying speed can be increased without requiring another lens system having high light transmission efficiency or another higher sensitivity photoelectric conversion element.

As described above, after passing through the first traveling original reading section 3b, the light of the second light source 450 is transmitted to the first traveling original reading section 3b.
The document is guided to the one-sided discharge path 42d, which is a conveyance path that does not block the light path leading to the first path, so that the light of the second light source 450 can be easily guided to the first traveling document reading unit 3b without changing the conveyance path. Therefore, in the one-sided reading mode, it is possible to use a light source on the side opposite to the surface of the original to be read, and it is possible to increase the illuminance of the original, so that the speed of transporting the original can be increased, The reading time of the document can be reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. For example, the same transport path is used in the single-sided reading mode as in the double-sided reading mode. In other words, the document transport path is a path from the first read transport path 42b to the double-sided discharge tray 44 via the second read transport path 42c.

At this time, in the single-sided reading mode, the second light source 4
The first traveling original reading unit 3b transmits the light of 50 through the reflection plate 37.
In order to guide the document, the light source is disposed on the side where the respective surfaces of the document face each other with the conveyance path therebetween, so that the distance between the first traveling document reading unit 3b and the second traveling document reading unit 3c is It should be larger than the length in the direction. If the document is transported at a speed higher than that in the double-sided reading mode, the document 1
The transport time for each sheet can be reduced. However, when reading a large number of documents, the rear end of one document in the transport direction is the second light source 4.
The transport timing is controlled so that the next original can be read by the first traveling original reading unit 3b while the optical path for guiding the 50 light to the first traveling original reading unit 3b is not blocked.

As another method, a movable light guide, for example, an optical fiber, which faces or retreats from the second light source 450, is provided, and passes through the outside of the transport path from the open portion 40 side to the main body portion 30 side. By laying to reach the second
An optical path from the light source 450 to the first traveling original reading unit 3b is formed. In the one-sided reading mode, the light guide faces the second light source 450, and the light of the second light source 450 is guided to the first traveling original reading unit 3b through the light guide to irradiate the original. In the double-sided reading mode, the light guide is retracted from the second light source 450, and the light from the second light source 450 is directly applied to the second traveling original reading unit 3c. In the case of this method, the conveyance path of the document may be branched in the single-sided reading mode and the double-sided reading mode as in the above embodiment, or may be the same conveyance path in each mode.

Further, as another method, the second light source 4
The 50 may be moved to the same side as the first light source 350. For example, a movement path is provided between the opening 40 and the main body 30 to enable the second light source 450 to move, and in the single-sided reading mode, move the second light source 450 from the opening 40 to the main body 30. , The first traveling original reading unit 3b
The light is emitted together with the light source 350. In the double-sided reading mode, the second light source 450 is on the opening 40 side and irradiates the second traveling original reading unit 3c.

In the above description, the scanning was performed with the respective light sources stopped with respect to the running original.
Conversely, a light guide that moves with the light source even when the original and the light source move relative to each other, such as when scanning is performed while moving each light source along the document while the document is stationary. Or a method of moving the light source to the same side can be applied.

[0075]

As is apparent from the above description, according to the present invention, by guiding the light of one light source to the reading unit corresponding to the other light source, the two light sources used for double-sided reading can be used for single-sided reading. Therefore, it is possible to increase the illuminance on the original surface during single-sided reading. This allows
Even if the document transport speed is increased, sufficient reading performance can be obtained, and the speed of reading one-sided documents can be increased.

When reading a two-sided original, the light from one light source is shielded so as not to reach the other reading unit. There is no need to correct the image. Further, when an optical path from one light source to the other reading section is formed so as to cross the document transport path, a white plate is used for a member that shields this optical path to reduce the amount of reflected light during double-sided reading. Can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus including a double-sided document reading device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of the same.

FIG. 3 is a configuration diagram of a two-sided document reading apparatus.

[Explanation of symbols]

 3b First reading unit 3c Second reading unit 35 First reading scanning system 37 Reflecting plate 38 White slide plate 45 Second reading scanning system 42b First reading conveyance path 42c Second reading conveyance path 42d Single-sided discharge path 350 First light source 450 First Two light sources

Continued on the front page (72) Inventor Yasuhiro Ono 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Hisashi Yamanaka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F term (reference) 2H076 AA58 BA58 BA68 5B047 AA01 BA01 BA07 BA08 BB03 BC06 BC08 BC12 BC18 CA08 CA19 CB16 5C062 AA05 AB02 AB32 AB46 AC09 AC11 AC12 AC65 AD01 BA02 BA04 5C072 AA01 BA03 BA05 CA02 DA15 DA17 RA21 NA08 XA01

Claims (9)

[Claims] 1. A transport path for transporting a document, transport means for transporting the document in the transport path, a first reading unit for reading one surface of the transported document, and a first reading unit for irradiating the same.
A first reading unit having a light source and arranged on one side of the document, a second reading unit for reading the other side of the conveyed document, and a second light source for irradiating the second reading unit on the other side of the document Distributed second reading means, light distribution means for guiding the light of the second light source to the first reading section when reading a one-sided original, the transport means, first reading means, second reading means, and light distribution means Control means for controlling one side of the document, the first reading means reads one side of the document while conveying the document at a first speed, and the second side reads the other side of the document during double-sided reading. The first reading unit irradiates the first reading unit with the first light source and the second light source while conveying the document at a second speed higher than the first speed during single-side reading, and controls the reading of the document by the first reading unit. A double-sided document reading device that performs control for reading one side. 2. An optical path from a second light source to a first reading section is formed so as to cross a transport path, and the light distribution means has a movable light shielding member for interrupting the optical path. The double-sided document reading device according to the above. 3. A first transport path for transporting a two-sided original, a second transport path for transporting a one-sided original, a first reading unit for reading one side of the transported original, and irradiating the same. A first reading unit having a first light source and arranged on one side of the document; a second reading unit for reading the other side of the conveyed document; and a second side of the document having a second light source for irradiating the second reading unit A second reading unit disposed on the side of the first light source and the light of the second light source.
A light distribution unit for switching between a first optical path leading to a reading unit and a second optical path leading to the second reading unit; the first reading unit;
Control means for controlling the reading means and the light distribution means,
The first reading unit is disposed in the first and second conveyance paths, and the second reading unit is provided in the first and second conveyance paths.
The control unit is arranged downstream of the reading unit, and reads the one side of the original by the first reading unit while transporting the original at the first speed during double-sided reading, and outputs the other side of the original by the second reading unit. The first optical path is switched while the original is being conveyed at a second speed higher than the first speed at the time of single-sided reading.
A two-sided document reading apparatus, wherein a light source and a second light source irradiate the first reading unit to control the first reading unit to read one side of the document. 4. The double-sided document according to claim 3, wherein the first optical path is formed so as to cross the first transport path, and the light distribution unit has a movable light shielding member that blocks the first optical path. Reader. 5. The double-sided document reading apparatus according to claim 2, wherein a reference white plate for shading in the second reading unit is used as the light shielding member. 6. The double-sided document reading apparatus according to claim 5, wherein the reference white plate is disposed outside the conveyance path. 7. A first conveyance path for conveying a document, a first reading unit for reading one side of the conveyed document, and a first light source for irradiating the first reading unit, the first reading unit being arranged on one side of the document. A reading unit, a second reading unit for reading the other side of the conveyed document, a second reading unit having a second light source for irradiating the second reading unit, and a second reading unit disposed on the other side of the document; A two-sided document reading apparatus, comprising: light distribution means for guiding light of the second light source to the first reading unit. 8. The light distribution means positions the second light source on the opposite side of the first light source with respect to the transport path when reading both sides, and positions the second light source on the same side as the first light source with respect to the transport path when reading one side. 8. The double-sided document reading apparatus according to claim 7, wherein the positional relationship between the second light source and the transport path is changed. 9. A first reading unit for reading one side of a document, a first reading unit having a first light source for irradiating the first reading unit and disposed on one side of the document, and a first reading unit for reading the other side of the document. A second reading unit, a second reading unit having a second light source for irradiating the second reading unit, and disposed on the other side of the document;
A double-sided document reading apparatus comprising: moving means for relatively moving a reading means; and light distribution means for guiding light of the second light source to the first reading section when reading a single-sided document.