JP2002359724A - Double-sided original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided original reader that can excellently read images on front and rear sides of an original by decreasing a difference of illuminance on the original surfaces between front side reading and rear side reading of the original. SOLUTION: Light sources 50, 81, a CCD 15 acting like a light receiving section and an image sensor 83 are respectively provided in 1st and 2nd read sections 10, 32 placed to an upper-stream side carrying path section 33b extended from a curved carrying path 102 toward an upper-stream in an original carrying direction nearly in a planar shape and to a downstream side carrying path section 33c extended toward a downstream in the original carrying direction nearly in a planar shape. Further, a reflection mirror 103 leading an emitted light from the light source 50 to a read area P2 of the 2nd read section is provided, and when the 2nd read section is used to read an original, even the light source of the 1st read section is driven and the reflection mirror 103 leads the emitted light from the 1st light source to the read area P2 of the 2nd read section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided document reading apparatus for reversing a document and reading images on both sides of the document.

[0002]

2. Description of the Related Art Conventionally, in a double-sided document reading apparatus for reading an image on both sides of a document while reversing the document, the focus of a reading optical system is switched between when reading the front side of the document and when reading the back side. A technique is known in which the front and back sides of a document are read by an optical system (see Japanese Utility Model Laid-Open No. 2-53664).

[0003]

However, in the above-mentioned conventional technique, the distance between the light source with respect to the document and the optical path length with respect to the image sensor element change between the front surface reading and the back surface reading. There is a problem that the difference becomes large and a problem that the position of the imaging lens for reading needs to be changed each time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is intended to reduce the difference in illuminance on the document surface between the front side and the back side of the document so as to read both sides of the document satisfactorily. It is an object of the present invention to provide a double-sided document reading apparatus that can perform the above-mentioned operations and can be easily downsized.

[0005]

The present invention has the following configuration to achieve the above object. According to a first aspect of the present invention, there is provided a document set unit for setting a document, a discharge unit for discharging a document, a curved conveyance path for guiding a document conveyed from the document set unit to the discharge unit, A first reading unit having a reading area on a side of the curved conveyance path on which one surface of the document faces, and a first reading unit on a side of the curved conveyance path on which the other surface of the document faces; And a second reading unit having a reading area downstream of the reading area in the document conveying direction.
A reversing conveyance path for substantially reversing the conveyance direction of the document, an upstream conveyance path extending in a substantially planar manner from the reversing conveyance path to the document conveyance direction upstream, and a document conveyance direction downstream from the reversal conveyance path. A downstream transport path extending in a substantially planar shape, wherein the first reading unit is provided in the upstream transport path, and
The reading unit is provided in the downstream transport path unit, the first reading unit has a first light source that irradiates light to the document and a first light receiving unit that receives light reflected from the document. The second reading unit includes a second light source that irradiates light to the document and a second light receiving unit that receives reflected light from the document, and emits light of the first light source to the second reading unit. When a document is read using the second reading unit, the first light source of the first reading unit is also driven, and the light source is guided from the first light source. The irradiation light of the second
A double-sided document reading device is characterized in that the document is guided to a reading area of a reading unit.

A second gist of the present invention resides in that when reading a document using the second reading section, the amount of light emitted from the first light source of the first reading section is controlled by the first reading section. The double-sided document reading apparatus according to the first aspect is characterized in that when reading a document by using the document, the amount of light emitted from the first light source is set to be smaller than that.

A third aspect of the present invention is the first aspect, wherein the second reading section is constituted by an equal-magnification optical system.
In the double-sided document reading apparatus described in (1).

A fourth aspect of the present invention is the double-sided document reading apparatus according to the first or third aspect, wherein the second reading section is provided inside the curved conveyance path.

A fifth aspect of the present invention is characterized in that the distance between the reading area of the second reading section and the curved conveyance path is shorter than the distance between the reading area of the first reading section and the curved conveyance path. And a double-sided document reading apparatus according to the fourth aspect.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing a configuration example of a double-sided document reading apparatus according to the present invention. The double-sided document reading apparatus includes a lower casing 1, an upper casing 2, and a document discharge tray 3.

The two-sided document reading apparatus can read an image of a document in a stationary reading mode in which the document is stopped and an image is read, or in a traveling reading mode in which the image is read while the document is being conveyed. The traveling reading mode includes a single-sided mode for reading a single-sided image of a document while conveying the document, and a double-sided mode for reading a double-sided image of the document.

In the one-side mode of the stationary reading mode and the traveling reading mode, an image is read by the first reading unit 10 in the lower housing 1. In the duplex mode of the traveling reading mode, the first reading unit 10 and the second reading unit 32
Are used at the same time to read images on both sides of the document.

The lower housing 1 is provided with a first reading section 10, a first contact glass 11, and a second contact glass 16. The first reading unit 10 is a reduction optical system (movable optical system), and includes a first scanning unit 12, a second scanning unit 13, an imaging lens 14, and a CCD 15. The first contact glass 11 is a table on which a document to be read in the static reading mode is placed.

The configuration of the first reading section 10 will be described in more detail. The first scanning unit 12 exposes the document while moving at a constant speed V in the sub-scanning direction (from left to right in the figure) along the first contact glass 11. A first exposure lamp, such as a xenon lamp, for exposing a document is used.
A light source 50, a first reflecting mirror 51, a reflector R, and a slit S for guiding reflected light of the document to the second scanning unit 13;
(Described later).

The second scanning unit 13 follows the first scanning unit 12 and moves at a speed of V / 2. The second scanning unit 13 transmits the light from the first reflecting mirror 51 to the imaging lens 14,
Second and third reflection mirrors 52 and 53 for leading to the CCD 15 are provided.

The imaging lens 14 forms an image of the light reflected from the third reflection mirror 53 on the CCD 15.
The CCD 15 converts light from the imaging lens 14 into an analog electric signal. This electric signal is
The image data is converted into digital image data by an image processing unit described later and stored in an image memory described later.

A wire (not shown) is wound around the first scanning unit 12 and the second scanning unit 13 so that they can be moved in the same direction in synchronization with each other. Then, it is moved in the left-right direction (sub-scanning direction) of FIG. 1 by a stepping motor (not shown) via this wire.

The first reading section 10 not only reads a document placed on the first contact glass 11 in the stationary reading mode but also moves the inside of the upper housing 2 in the traveling reading mode as described later. It also has a function of reading an image of a conveyed document.

When reading a document on the first contact glass 11, the first scanning unit 12 moves the document detected by the document size detecting means from the position pos1 to the position pos2 in FIG. It moves by a predetermined distance according to the size. On the other hand, when reading the conveyed document, it stops at the position pos3 in FIG. In addition, during standby when not in use, it is stopped at the position of pos0 (home position) between the positions of pos1 and pos3 in FIG. In addition, pos
The position of 3 indicates that the conveyed document is almost flat (including flat)
Are located on the transport path that forms

As shown in FIG. 2, an original reference plate 41 is provided on the left end side of the first contact glass 11 in the drawing.

On the reference plate 41, an index indicating the size and mounting direction of the original placed on the first contact glass 11 is shown. According to this indicator, the user
An original can be easily placed on the contact glass 11.

Further, on the side of the first contact glass 11 opposite to the side on which the document reference plate 41 is provided, and at a position facing the document reference plate 41, shading of the CCD 15 (determination of white level) is performed. A first reference white plate 42 is provided for use in the operation.

The upper housing 2 rotates upward with a hinge (not shown) provided between the upper housing 2 and the lower housing 1 (on the back side of the apparatus) as a rotation fulcrum. Thus, in this double-sided document reading apparatus, the upper surface of the first contact glass 11 and the upper surface of the second contact glass 16 can be opened from the near side. And the upper housing 2
As shown in FIG. 1, the OC mat 21 and the document tray 2
2, a second reading unit 32, an open door 24, and a document conveying unit 31 are arranged.

The OC mat 21 is a white sheet provided at a position where the upper mat 2 is pressed against the first contact glass 11 when the upper casing 2 is closed, and is provided with an elastic foam such as a sponge on the back side thereof. It has.

The document tray 22 is a table on which documents to be read in the traveling reading mode are placed.

The open door 24 is used to adjust the mounting state of the second reading unit 32 and the mounting state of the second reading unit 32.
It is an openable and closable door provided on the upper surface of the upper housing 2.

The second reading section 32 is for reading an image of a document placed on the document tray 22, and includes an image sensor section 71 and a holding section. The second reading section 32 reads an image of a conveyed document. The details of the second reading unit 32 will be described later.

The document transport section 31 is a transport section for guiding a document placed on the document tray 22 to a U-shaped transport path 33.

The U-shaped transport path 33 is a transport path that transports the original sent from the original transport section 31 to the reading areas of the first and second reading sections 10 and 32 and guides the original to the original discharge section 34. A curved conveyance path (U-turn paper guide) that curves in a bowl shape or a substantially U shape (including a U shape) in the conveyance direction
A U-shaped conveyance path 33 having a second path 102. Curved transport path 1
02 indicates that the transport direction of the document is substantially reversed before and after that (approximately 180
(Including inversion, 180 degrees)), and it is desirable that the transport path before and after inversion is formed in a laminated shape in which the conveyance paths are substantially parallel (including parallel) in the left-right direction and the depth direction as viewed in the drawing. However, in consideration of the arrangement of components and the like, the transport path before and after the reversal may not be parallel in the left-right direction and / or the depth direction in the drawing. Therefore, the original placed on the original tray 22 is not
1 and is taken into the U-shaped transport path 33, and is substantially inverted in the curved transport path 102 and discharged onto the paper discharge tray 3.

The document discharge section 34 discharges the document whose image has been read by the second reading section 32 to the discharge tray 3.

In the vicinity of the side of the second reading section 32, a reflection mirror 103 serving as a light guide is provided. This reflection mirror 103 extends in the main scanning direction. And
The reflection mirror 103 reflects the light from the first scanning unit 12 and sets the angle of the reflection surface so that the light can be guided to the original irradiation position (reading area) P2 by the second reading unit 32 through the third contact glass 17. And is fixed at a predetermined position.

FIG. 2 shows the document transport unit 31 and the second reading unit 3
FIG. 2 is a partial cross-sectional view showing a configuration near a document discharge unit 34 in detail.

The document conveying section 31 includes a feeding auxiliary roller 61,
Document set detection sensor 62, document holding plate 63, friction pad 64, feed timing sensor 65, feed roller 66,
And an alignment roller pair 67.

Feeding assist roller 61 and document holding plate 63
Is for drawing a document detected by the document set detection sensor 62 into the document transport unit.

The friction pad 64, the feed roller 66, and the alignment roller pair 67, based on the detection result of the feed timing sensor 65, scan the pulled-in documents one by one into the first reading unit 10 and the second reading unit 32. Lead to.

The aligning roller pair 67 has an electromagnetic clutch (not shown) on its drive shaft so that transmission of a driving force from a drive motor (not shown) can be controlled, and there is no original. It is stopped in the state. After the leading edge of the document comes into contact with the feed timing sensor 65 and a predetermined signal is transmitted from the timing sensor 65, a predetermined time for forming the deflection of the document upstream of the nip portion of the pair of alignment rollers 67 after the predetermined signal is transmitted. When the time elapses, the document is set to rotate in the direction of transporting the document to the downstream side. After the alignment roller pair 67 is stopped, the leading end of the document conveyed from the upstream side by the friction pad 64 and the feed roller 66 abuts on the nip portion of the alignment roller pair 67, and after a predetermined bending is formed on the document. , So that the document is conveyed downstream. At this time, the document is aligned by the nip portion of the pair of alignment rollers 67 such that the leading end of the document is perpendicular to the transport direction.

The U-shaped conveyance path 33 includes a gap between the conveyance guide 58 and the feeding roller 66, a gap between the alignment roller pair 67 and the second contact glass 16, a curved conveyance path 102, and the document guide 70 and the reference white plate 68. This is a document conveying path having a gap with the original.

The document guide 70 is placed after the U-first rear roller pair 101 with the third contact glass 17 provided at the central opening OP. In addition,
The positions of the document guide 70 and the reference white plate 68 of the second reading section 32 are set by positioning projections 70 a provided with the third contact glass 17 interposed in the conveyance direction of the document guide 70. This will be described later. The third contact glass 17 is provided with a concave opening OP on the conveyance path side of the document guide 70.
Are bonded with an adhesive.

The document discharge section 34 includes a discharge roller pair 69 and a document discharge sensor 59. The upper roller of the discharge roller 69 is a roller on the driving side, is provided integrally on the upper housing 2, and is driven by a driving mechanism in the upper housing 2. The upper roller of the discharge roller 69 has a function of pinching and conveying the document that has passed through the U-shaped conveyance path 33 with the lower roller (driven roller) of the discharge roller 69 and discharging the document onto the discharge tray 3. are doing.

The document discharge sensor 59 is disposed downstream of the discharge roller 69, and detects the completion of document discharge.
This is transmitted to a reading control unit described later.

The second reading section 32 is provided in the upper housing 2 and is for reading an image on the back side of the document surface read by the first reading section 10 of the document traveling on the U-shaped conveyance path 33. It is. Further, the second reference white plate 68 provided opposite to the second reading unit 32 determines the white level when shading the electric signal output from the image sensor unit 71 (determining the white level). And a paper guide for document transport. Further, the second reading unit 32 is provided with the first scanning unit 12.
Pos3, the two reading units prevent the images from being unable to be read at an appropriate density.

FIG. 3 is an explanatory diagram showing a configuration near the second reading section 32. In the embodiment shown in FIG. 3, the curved conveyance path 102 is provided in the U-shaped conveyance path 33, and the first scanning unit 12 as the first reading unit 10 is provided upstream of the curved conveyance path 102.
(Pos 3 position), the second reading unit 32 is provided on the downstream side so as to face the first scanning unit 12. That is, the first reading unit 10 that reads the surface of the document is substantially straight (including a straight line) extending upstream of the curved conveyance path 102 of the U-shaped conveyance path 33 in the document conveyance direction, and upstream of a substantially flat surface (including a flat surface). The second reading unit 32 that is disposed in the transport path 33b and reads the back surface of the document is disposed in a substantially straight, substantially planar downstream transport path 33c that extends downstream of the curved transport path 102 in the document transport direction.

The transport directions of the first reading unit 10 and the second reading unit 32 are reversed by approximately 180 degrees (including 180 degrees).

The second reading section 32 includes an image sensor unit 71, a unit fixing plate 73, a unit holding plate 74, and the like.

The image sensor unit 71 is disposed facing the third contact glass 17 provided at the center of the document guide 70. This third contact glass 17
Has a function of realizing light transmission between the image sensor unit 71 and the document and a function of preventing the document from being jammed.

The image sensor unit 71
Is mounted via a unit fixing plate 73 and a unit holding plate 74 with respect to a reference plate 72 fixed between the front and rear frames of the upper housing 2 of the apparatus.

As shown in FIG. 3, the image sensor unit 71 has a light source 8 for illuminating the original surface inside the image sensor unit 71.
1 (LED array, etc.), Selfoc lens array 82 for condensing light reflected from a document, and an image sensor (second photoelectric conversion element) for generating an electric signal (electric image signal) according to the intensity of the received light 83 are provided.

The light source 81 is set to a length capable of irradiating the entire width of the document to be conveyed. In the present embodiment, the light source 81 has substantially the same length as the width of the U-shaped conveyance path 33 perpendicular to the conveyance direction. . Further, two light sources 81 are provided in parallel with respect to the document transport direction with an image sensor (second photoelectric conversion element) 83 interposed therebetween.

When shading the output signal of the image sensor 83, the image sensor unit 71
The second reference white plate 68 is read via the contact glass 17. The shading value is determined based on the read value, and the electric signal output from the second reading unit 32 when the document image is read is shaded (white part level is determined).

The focal point of the selfoc lens array 82 is
The height of the U-shaped conveyance path 33 (the gap between the document guide 70 and the reference white plate 68 of the second reading unit) is slightly higher than the center of the U-shaped conveyance path 33.
The reading unit is set so as to match the reference white plate 68. As a result, the depth of field of the selfoc lens array 82 occupies most of the height of the U-shaped conveyance path 33 from the surface of the reference white plate 68 of the second reading unit. Therefore, the reflected light from the second reference white plate 68 received by the image sensor (second photoelectric conversion element) 83 is at the same level as the reflected light from the white portion of the document passing through the U-shaped conveyance path 33.

An original guide 70 made of a light shielding member facing the second contact glass 16 has a first scanning unit 1
2, a slit 75 extending in the main scanning direction (a direction perpendicular to the drawing) is formed at a position facing the reading area P1 at the position of pos3.
It is provided with fitting. Thus, in the traveling reading mode, if no original exists on the slit 75, the first scanning unit 1 stopped at the position pos3
The light emitted from the second light source 50 is emitted toward the downstream straight path 33 c through the slit 75, is further reflected by the reflection mirror 103, and is reflected by the third contact glass 17.
The document is guided to a document irradiation position (reading area) P2 by the second reading unit 32 through the. In the traveling reading mode,
When the leading edge of the document reaches the reading area of the second reading unit 32, the document from the position of the slit 75 to the reading area of the second reading unit 32 such that the rear end of the document has passed through the slit 75. The transport path length is set.

Next, the installation configuration of the image sensor unit 71 will be described. FIG. 4 is a partial perspective view illustrating a configuration of an installation portion of the image sensor unit 71. As shown in the figure, the reference plate 72 has a large opening 72 at the center.
a is formed, and both ends of the opening 72a in the transport direction are bent and raised. A unit fixing plate 73 is hung over the two bent and raised portions 72b, and is fixed by a plurality of fixing screws 76.

The unit holding plate 74 has a hollow quadrangular prism shape, and the unit fixing plate 73 is passed through the unit holding plate 7 by adjusting screws 77 with the unit fixing plate 73 penetrating inside.
4 from above.

The image sensor unit 71 is firmly fixed to the unit holding plate 74. In addition, the height position and posture (degree of inclination) of the unit holding plate 74 with respect to the reference plate 72 and the height position and posture of the unit fixing plate 73 with respect to the unit holding plate 74 are adjusted by the fixing screw 76 and the adjusting screw 77. By doing so, it is possible to shift within a predetermined range.

That is, in this double-sided document reading apparatus, the attitude and the height position (the third
The relative position with respect to the contact glass) can be controlled in minute units by adjusting the screws 76 and 77 described above. Accordingly, it is easy to dispose the image sensor unit 71 strictly at an optimum posture and position.

Further, as shown in FIG.
Is fixed to an end of the reference plate 72 by a stepped screw 78 and a guide urging spring 79. This allows U
The height of the character-shaped conveyance path 33 (the distance between the document guide 70 and the second contact glass 16) can be kept constant even if there is a variation in the accuracy of each component.

The screws can be adjusted from above the upper housing 2 by opening the opening door 24 shown in FIG. Further, as shown in FIG. 5, the setting is such that the entirety of the second reading unit 32 can be attached and detached by opening the opening door 24.

Next, a reading process in the double-sided document reading apparatus will be described with reference to FIGS. In the stationary reading mode, only the first reading unit 10 is used for reading a document. At this time, the first scanning unit 12 of the first reading unit 10 is first arranged at pos0. Then, in response to an instruction from the reading control unit, the first position from the position of pos1 is
While scanning the original placed on the contact glass 11, the original moves to the pos2 side together with the second scanning unit 13. This allows the CCD 15 to receive reflected light according to the document image. As described above, the first reading unit 10 reads an image formed on the lower surface (front surface) of the stationary document.

In the traveling reading mode, both the single-sided mode and the double-sided mode can be selected. In the one-side mode of the traveling reading mode, only the first reading unit 10 is used for reading a document. When there is an instruction in this mode, the first reading unit 10
The first scanning unit 12 moves from the position of pos0 to the position of pos3 in FIG. 1 and stops, and keeps the stopped state to read the traveling document. Then, in response to an instruction from the reading control unit, the CCD 15 reads the image of the document conveyed through the U-shaped conveyance path 33 via the second contact glass 16 from below in FIG. That is, the first reading unit 10 reads an image formed on the lower surface (front surface) of the document.

In the duplex mode of the traveling reading mode, both the first reading section 10 and the second reading section 32 are used for reading a document. At this time, the first scanning unit 12 of the first reading unit 10 is stopped at the position of pos3 in FIG. 1 as in the one-side mode in the traveling reading mode.

Then, according to the instruction of the reading control unit,
The first reading unit 10 reads an image of a document conveyed through the U-shaped conveyance path 33 from the lower side (front side) via the second contact glass 16 in the reading area P1. Also, similarly, the second reading unit 32 is connected to the third reading unit 17 via the third contact glass 17.
An image formed on the upper surface (back surface) of FIG. 1 of the conveyed document is read. At this time, the light from the first scanning unit 12 is guided to the original reading area P2 by the second reading unit 32 via the slit 75, the reflection mirror 103, and the third contact glass 17, and together with the light from the second reading unit 32. Irradiated on the back of the document.

When the back side of the original is read by the second reading section 32, the light from the first reading section 10 is irradiated together with the light from the second reading section 32 onto the back side of the original, so that the front side and the back side of the original are read. It is possible to reduce the difference in illuminance between the original and the original at the time of reading, so that both sides of the original can be read well. That is, while a lamp light source having a large light amount such as a halogen lamp is used as the light source 50 of the first reading unit 10, an LED is used as the light source 81 of the second reading unit 32.
Since a light emitting device with a small amount of light, such as an array, is used, the light from the light source 81 of the second reading unit 32 alone tends to be insufficient in the amount of light when reading the back surface due to the dispersion of light. By irradiating the light from the reading unit 10 to the back surface of the document as auxiliary light, it is possible to eliminate the shortage of light amount when reading the back surface.

When reading a document by the second reading unit 32, the light amount of the light source 50 of the first reading unit 10 is
By adjusting the light amount so that the light amount is smaller than when reading the original, it is possible to eliminate the image jump due to the excessive light amount when reading the back surface.

That is, the first reading unit 10 and the second reading unit 3
2 includes a document irradiation light source (50, 81) and an image sensor (15, 83) for generating an electric signal (electric image signal) corresponding to the intensity of the received light. In the mode, the other light source can be assisted and adjusted.

Further, since both sides of the original can be read only by transporting the original using the original transport section 31 and the original discharge section 34 formed in the upper housing 2, the structure can be simplified.

The first reading section 10 is a reduction optical system (movable reading optical system), and the second reading section 32 is a 1 × optical system (fixed 1 × reading optical system (CIS)). Since the document alignment means needs to be provided only at one location of the first reading unit 10, the conveyance control becomes easy. Therefore, for a user who mostly reads one-sided originals and hardly needs to read two-sided originals, the problem that the apparatus becomes large due to the double-sided original reading function, the configuration becomes complicated, and the cost becomes high is solved. it can.

Further, by forming the second reading section 32 by a 1: 1 optical system (fixed 1: 1 reading optical system (CIS)) which can be configured compactly, the second reading section 32 can be disposed inside the U-shaped transport path 33. This makes it easy to reduce the size of the device in the height direction.

Further, since the shielding member constituting the U-shaped conveyance path 33 is interposed between the first reading section 10 and the second reading section 32, the irradiation lights of the reading sections are prevented from interfering with each other. be able to.

Further, by making the distance between the reading area P2 of the second reading section 32 and the curved transport path 102 shorter than the distance between the reading area P1 of the first reading section 10 and the curved transport path 102, the first Since the reading section and the second reading section can be arranged in a stacked manner, the entire apparatus can be made compact.

In this double-sided document reading apparatus, the second reading section 32 can be attached and detached by opening the opening door 24. That is, the second reading unit 32 can be mounted from above the transporting unit with few other members. This allows
The attachment / detachment of the second reading unit 32 can be facilitated. Further, the degree of freedom in designing other members can be increased.

Further, in this double-sided document reading apparatus, the height position and posture of the image sensor unit 71 in the second reading section 32 can be easily adjusted with respect to the U-shaped conveyance path 33. Thereby, it is possible to easily eliminate the displacement of the second reading unit 32 which causes the deterioration of the image quality.

Further, in this double-sided document reading apparatus, the height position and posture of the document guide 70 can be adjusted. Accordingly, the height of the U-shaped conveyance path 33 (the height of the third contact glass 17) can be set to an optimum value, and thus a sheet jam can be prevented.

The reading units 10 and 3 are respectively provided on the upstream and downstream straight transport paths 33b and 33c of the curved transport path 102.
Since the gap 2 is provided, even if the gap of the U-shaped conveyance path 33 through which the sheet passes is narrowed, no jam occurs and the reading can be stably performed.

Further, by forming the second reading section 32 with a 1 × optical system (fixed optical system) that can be made compact,
Since the apparatus can be arranged inside the character-shaped transport path 33, the apparatus can be easily reduced in the height direction.

Further, the U-shaped conveyance path 33 is
The upper side can be opened, so that the jam can be easily removed.

Next, a control system of the double-sided document reading apparatus will be described with reference to FIG. In FIG. 6, the system controller 84
It controls the reading control unit 86, and further controls the image processing relay unit 88 and the image memory 89 via the system bus 87. Thus, the system controller 84 controls the entire double-sided document reading device so that the document reading operation is properly performed.

The first light source substrate 90 turns on and off the light source 50 of the first reading unit 10 based on the signal of the reading control unit 86. The second light source substrate 91 turns on / off the light source 81 of the second reading unit 32 based on a signal from the reading control unit 86.

First reading scanning system drive motor control board 92
Controls the first reading / scanning system driving motor 93 based on the signal of the reading control unit 86 to move the first scanning unit 12 and the second scanning unit 13 in both the left and right directions in FIG.

In the first reading scanning system position sensor group 94, the first scanning unit 12 includes pos0, pos1, pos2,
When it is located at pos3, it sends a reference position signal to the reading control unit 86.

The reading control unit 86 determines the first scanning unit 12 based on the reference position signal of the first reading scanning system position sensor group 94 and the number of steps of the first reading scanning system driving motor 93.
Is calculated, and the first reading / scanning system drive motor 93 is controlled to rotate forward / reverse to reciprocate the scanning units 12 and 13.

The drive motor control board 95 of the automatic document feeder (document transport unit 31 and document discharge unit 34) controls the drive motor 96 as a stepping motor on and off in response to a signal from the read control unit 86, and performs automatic document feed. Devices 31, 3
The drive system of No. 4 is driven to transmit the driving force to the above-described paper feed rollers 61 and 66, the separation / feed unit, the pair of alignment rollers 67, the discharge roller 69, and other transport rollers. The drive motor 9
6 can change the rotation speed by the pulse rate from the drive motor control board 95.

The document discharge sensor 59, document set detection sensor 62, and feed timing sensor 65 (document detection sensor group) transmit a document presence / absence signal to the reading control unit 86 when the document reaches the position of each sensor. .

On the other hand, the reading control section 86 calculates whether or not the original is being conveyed at an appropriate timing based on the presence / absence signal of the original from the sensor group 59, 62, 65 and the timer, and conveys the original. In the case of a failure, a signal of occurrence of a jam or the like is transmitted to the system controller 84 via the system bus 87.

The document conveying roller clutch group 97 is turned on / off by a signal from the reading control unit 86 to switch connection or non-connection to each drive system of the automatic document feeder to stop the drive system. Or rotate.

Next, the processing of the electrical image signal obtained by the reading scan in the single-side reading mode and the double-side reading mode will be described.

The CCD 15 and the second reading section 32 (CIS
83), the electrical image signal (hereinafter, referred to as an image signal) is sent to an image processing unit IP, and after being subjected to predetermined image processing, sent to an image processing relay unit 88.
After predetermined image processing is performed, the system bus 87
And stored in the image memory 89 while being distinguished for each page.

The image processing unit IP includes an analog signal processing unit I
1, an A / D conversion unit I2, a shading correction unit I3, a filter processing unit I4, and a density conversion unit I5.
Each element of the image processing unit IP operates under the control of the reading control unit 86.

The analog signal processing section I 1
The image signal input from the CD 15 and the second reading unit 32 (CIS 83) is subjected to a level conversion process, a sample hold process, and a signal amplification process, and is output to the A / D conversion unit I2. Since the CCD 15 and the second reading unit 32 have different light source light amounts, photoelectric conversion efficiencies, output signal levels, and the like, dedicated analog signal processing units I1 are provided for the CCD 15 and the second reading unit 32, respectively.

The A / D conversion section I2 converts the analog image signal input from the analog signal processing section I1 into a digital signal, and converts the quantized image signal into a shading correction section I3.
Output to

The shading correction unit I3 performs black reproduction and white reproduction on the quantized image signal input from the A / D conversion unit I2, and outputs the result to the filter processing unit I4.

The black reproduction means that the implicit output of the CCD 15 or the second reading unit 32 is sampled and stored, and the data is subtracted from the image data output from the CCD 15 or the second reading unit 32 when reading the document, which is the read data. By doing
This is to remove the effect of the implied output.

The white reproduction means that an image signal at the time of reading an original is normalized to each pixel based on an image signal of each pixel when a reference white plate having a uniform reflectance is read, and unevenness in light amount and influence of optical components. And correcting variations in pixel sensitivity of the first photoelectric conversion element 15 and the second photoelectric conversion element 83.

Filter processing section (filter processing means) I4
A predetermined filtering process based on a coefficient that determines a filter characteristic set from the reading control unit 86 on the image signal input from the shading correction unit I3, specifically,
By performing a spatial filtering process, high-frequency components of the image are emphasized, and "blur" of the image is restored.

That is, the CCD 15 and the second reading unit 3
The image signal output by the optical disc 2 includes optical components such as a lens and a mirror, the aperture opening of the light receiving surface of the CCD 15 and the second reading unit 32, the transfer efficiency and the afterimage of the CCD 15 and the second reading unit 32, and the physical scanning. The MTF (Modulation Transfer Function) is deteriorated due to the integration effect and scanning unevenness, and the filter processing unit I4 compensates for the MTF deterioration.

As described above, the MTF is connected to the CCD 15 and the second
Since the degree of deterioration greatly differs depending on the reading unit 32, appropriate filtering is performed. Further, since the deterioration of the MTF is more remarkable in the higher frequency range, the filter processing unit I4
In the Japanese Patent Application Laid-Open No. H08-115, an image signal in a high-frequency range is subjected to an emphasis process, thereby correcting "blur" and improving image quality.

The filtering section I4 determines that the input image signal is C
Different filter processing is performed depending on whether the signal is an image signal from the CD 15 or an image signal from the second reading unit 32.

Density conversion unit (density conversion means, binarization means)
I5 is for performing density conversion on the image signal filtered by the filter processing unit I4. For example, the image signal is transmitted when facsimile communication of the image signal is performed or when the printing condition is designated to be binarized. Is binarized, and
If the printing condition is multi-valued, such as a photographic image, the image quality is improved by performing density conversion using a predetermined density characteristic.

The density conversion section I5 includes a RAM, a RAM control section (not shown) and the like, and performs data conversion by reading a lookup table for data conversion set in the RAM as an address of an input image signal. hand,
Perform density conversion processing. The image signal for which the density conversion processing has been completed is stored in the image memory 89.

In the above-described embodiment, the image reading is performed using the first reading unit 10 in the one-side mode of the traveling reading mode. However, the present invention is not limited to this. The image may be read using the unit 32.

[0100]

As described above, according to the first aspect of the present invention, there is provided an upstream conveyance path extending from the reverse conveyance path to the upstream side in the document conveyance direction in a substantially planar shape; The first reading section and the second reading section provided on the downstream side transport path section extending in a substantially planar shape on the downstream side in the document transport direction are provided with a light source and a light receiving section, respectively, so that the first reading section and the second reading section are provided. It is possible to read the front and back sides of the same original independently of each other while preventing optical mutual interference of the copies, thereby shortening the duplex copying time. When the back side of the document is read by the second reading section, the light from the first reading section is irradiated on the back side of the document together with the light from the second reading section. In this case, it is possible to realize a double-sided document reading apparatus capable of reducing the difference in illuminance on the document surface and reading both the front and back of the document satisfactorily.

According to the second aspect of the present invention, when an original is read by the second reading section, the light amount of the light source of the first reading section is set to the first level.
By adjusting the light amount so as to make the light amount smaller than when the original is read by the reading unit, it is possible to prevent the image from jumping due to the excessive light amount when reading the back surface.

According to the third aspect of the present invention, when the second reading unit is constituted by the same-magnification optical system, the distance (optical distance) between the reading area and the light receiving element of the reading unit is smaller than that of the equal-magnification optical system. As compared with the case where a reading unit including a reduced optical system having a long and long rejection is arranged, a compact configuration can be achieved, so that the degree of design freedom can be increased.

The fifth gist of the present invention is that the second reading section is provided inside the curved conveyance path, thereby effectively utilizing the inside of the curved conveyance path and reading the two-sided document in a compact configuration. The device can be configured.

A sixth gist of the present invention is that the distance between the second reading section and the curved conveyance path is shorter than the distance between the first reading section and the curved conveyance path, so that the first reading section and the curved conveyance path can be connected to each other. Since the two reading units can be arranged in a stack, the entire apparatus can be made compact.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a two-sided document reading apparatus according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a more detailed configuration of a part of the duplex document reading apparatus of FIG. 1;

FIG. 3 is an enlarged view showing a configuration example of a portion of a U-shaped conveyance path.

FIG. 4 is a partial perspective view illustrating a configuration of an installation unit of a second reading unit.

FIG. 5 is an operational explanatory view of an attaching / detaching operation of a second reading unit.

FIG. 6 is a block diagram illustrating a configuration of a control system of the duplex document reading apparatus.

[Explanation of symbols]

 3 Document discharge tray 10 First reading unit 15 CCD 22 Document tray 32 Second reading unit 33 U-shaped conveyance path 33b Upstream conveyance path 33c Downstream conveyance path 50 First light source 75 Slit 81 Light source 83 Image sensor 102 Curved conveyance Road 103 Reflecting mirror 104 Transmission glass P1, P2 Reading area

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Ida 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Hidenori Onishi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Masami Tsuchida 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (72) Inventor Eiji Sato 22-22, Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation F Term (Reference) 5B047 AA01 BA07 BB02 BC05 BC09 BC12 BC14 CA17 CA19 CB16 5C051 AA01 BA03 BA04 DA02 DB01 DB22 DB24 DB28 DC04 DC05 DC07 DE09 DE26 DE29 5C072 AA01 BA01 CA02 CA11 CA14 DA02 DA04 DA21 DA23 DA25 EA05 EA07 MB04

Claims (5)

[Claims] 1. A document setting section for setting a document, a discharge section for discharging a document, a curved conveyance path for guiding a document conveyed from the document setting section to the discharge section, and a curved conveyance path. A first reading unit having a reading area on one side of one side of a document in the middle, and a reading area of the first reading unit on the side of the curved conveyance path on the side opposite to the other side of the document; And a second reading unit having a reading area on the downstream side in the document conveying direction. The double-sided document reading apparatus, wherein the curved conveying path includes a reversing conveying path that substantially reverses the conveying direction of the document; An upstream conveyance path portion extending in a substantially planar shape from the portion to the document conveyance direction upstream side, and a downstream conveyance path portion extending in a substantially planar shape from the reverse conveyance path portion to the document conveyance direction downstream side; A reading unit provided in the upstream transport path unit; A first light source that irradiates the original with light and a first light receiving unit that receives light reflected from the original; The second reading unit includes a second light source that irradiates light to the document and a second light receiving unit that receives reflected light from the document, and irradiates light emitted from the first light source to the second reading unit. In the case where a light guide unit for guiding to a reading area is provided and a document is read using the second reading unit, the first light source of the first reading unit is also driven, and the light from the first light source is output. A two-sided document reading apparatus, wherein the irradiation light is guided to a reading area of the second reading unit by the light guiding means. 2. When reading a document using the second reading unit, the amount of light emitted from the first light source of the first reading unit is used to read the document using the first reading unit. 2. The double-sided document reading apparatus according to claim 1, wherein the amount of light emitted from the first light source is smaller than the amount of light emitted from the first light source. 3. The double-sided document reading apparatus according to claim 1, wherein the second reading unit is configured by an equal-magnification optical system. 4. The double-sided document reading apparatus according to claim 1, wherein the second reading unit is provided inside a curved conveyance path. 5. The apparatus according to claim 4, wherein the distance between the reading area of the second reading unit and the curved conveyance path is shorter than the distance between the reading area of the first reading unit and the curved conveyance path. Double-sided document reading device.