Image reader

An image reader has a transport passage for transporting an original, a CIS for reading an image on the original transported on the transport passage, and a control member for pressing the transported original against an abutment member disposed at an opposed side of the transport passage at a read position of the CIS. The original does not slide on glass at the read position of the CIS and is moved with the original abutted against the abutment member of a chute on the opposed side, and image data is read in sequence.

The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-199641 filed Jul. 9, 2002, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an image reader for reading an original image by an image sensor and the like, particularly to an image reader installing a CIS (Contact Image Sensor).

2. Description of the Related Art

Hitherto, an image reader for automatically reading image information on both sides of an original without the intervention of the user (automatic double-side reader) has been widely used as a reader of a copier, a facsimile, etc., or a scanner for computer input. As the automatic double-side readers, a method of reversing the side of an original in an original reversal section and reading image information is most widely adopted. That is, to input image information on both sides in the method in the related art, one side is read in an original read section and then the side of the ejected original is reversed and again is transported to the original read section for reading the other side.

However, in the automatic double-side reading by inverting the side, it is necessary to reverse the original after once being ejected and again transport the original to the original read section and thus it takes much time in reading both sides and the productivity is poor in reading both sides. The original reversal section requires a complicated mechanism to reverse the side of an original and the original jam occurrence percentage in the original reversal section is high as compared with other transport sections. Improving the reliability is required. Further, to design an automatic double-side reader that is placed in a narrow space, the necessity for inverting an original rapidly in a small diameter may occur because of the necessity for inverting the original and collating the pages of the original at the paper ejection time, etc. Consequently, it is difficult to transport an original of a predetermined cardboard having a large basis weight.

An art of automatically reading both sides in one transport is studied. For example, in JP-A-1-171360 and JP-A-1-293757, two image sensors are placed on both sides of an original path for transporting an original and both sides of an original can be read automatically in one original transport without reversing the side of the original.

Generally, to read an original, for example, a technique of applying light from a light source of a fluorescent lamp to the original and reading the reflected light by an optical sensor through a reduction optical system is adopted. As the sensor in the technique, for example, a one-dimensional CCD (Charge Coupled Device) sensor is used to process one line at a time. Upon completion of reading one line in the line direction (main scanning direction), the original is moved a minute distance in the direction orthogonal to the main scanning direction (subscanning direction) and the next line is read. This operation is repeated over the whole original size for completing reading of one page of the original. As a method of reading an original in order in the subscanning direction without moving the original, a method of moving a plurality of mirrors by a moving body such as a full-rate carriage or a half-rate carriage for reading an original in order in the subscanning direction is also available.

In the read technique, it is necessary to apply a light source to an original and reading the reflected light by a CCD sensor through several mirrors as described above and thus the whole unit tends to become large. Particularly, if a plurality of image sensors need to be placed to read both sides without reversing an original, it is difficult to place a plurality of CCD sensors because of a space problem. To solve the space problem, use of an image sensor called CIS (Contact Image Sensor) for directly reading an image by a linear sensor through a SELFOC lens using a small LED (Light Emitting Diode) as a light source is studied.

However, in the read technique using the CIS, the focal depth is very shallow and if the CIS and an original face go out of distance even a little, out-of-focus occurs and the read image becomes unclear. That is, it becomes hard to provide a sharp image although the whole unit can be reduced.

To lessen defocus as much as possible, conventionally, an original is pressed against a glass face disposed on CIS and is transported and the original pressed against the glass face is focused. However, if the original is pressed against the glass face and is transported, pencil carbon, ink, garbage, dirt, etc., are pressed against the glass face and rub the glass face, and are is easily deposited on the glass face. If the read image is output with the pencil carbon, ink, garbage, dirt, etc., deposited on the glass face, a black line in the original transport direction (subscanning direction) appears and measures against image quality trouble must be taken.

Further, to adopt both a scanner for applying a light source to an original and reading reflected light by a CCD sensor through several mirrors and a reader using a CIS and make it possible to read both sides of the original at the same time, the reader using a CIS is generally placed to direct downward and the glass thereof is placed on the upper side relative to an original transport passage. In such a case, the user cannot sufficiently clean the dirty glass surface. Particularly, if the glass face in the reader using a CIS cannot be opened because of the structure, it becomes difficult for the user to clean the glass surface.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to control the attitude of a transported original at an image read section.

It is another object of the invention to suppress intimate contact of a transported original with a reader.

It is still another object of the invention to lessen dirt deposition on a reader.

An image reader incorporating the invention is characterized by the fact that an original is read by a CIS (Contact Image Sensor) with the original pressed against a chute on an opposed side without bringing the original into contact with a glass face placed in an original transport passage, thereby suppressing deposition of ink, etc., on the glass face and lessening the frequency of cleaning the glass surface, etc. That is, the image reader incorporating the invention comprises a transport passage for transporting an original, a CIS for reading an image on the original transported on the transport passage, and a control member for pressing the transported original against an opposed side of the transport passage at a read position of the CIS. However, the invention is not intended for completely preventing the original from being brought into contact with the glass face; when an original is read, control is performed so as to prevent the original from being brought into contact with the glass face as much as possible, and the lead, rear, etc., of the original is not completely prevented from coming in contact with the glass face.

The control member is characterized by the fact that it is projected from the CIS side of the transport passage toward the opposed side of the transport passage. More specifically, the spacing between a projection tip and the opposed side is 1 mm or less, and the member shaped like an ark, a square, etc., for example, is formed in the direction orthogonal to the original transport direction. Preferably, the projection is straight, but both end parts in the direction orthogonal to the original transport direction can also be made high as for the dimensions of the projection.

Further, the CIS is characterized by the fact that it is brought into focus assuming an original positioned on the opposed side of the transport passage. More specifically, for example, assuming that an original about 0.1 mm thick abuts the chute on the opposed side, adjustment is made so that the center point of the focus comes onto the original, for example. The CIS is characterized by the fact that it is placed with the sensor face pointing downward and acquires reflected light from an original passing through a light transmission member (for example, a glass member) placed at a midpoint in the transport passage.

From another aspect of the invention, an image reader incorporating the invention comprises read means for using reflected light from an original passing through a light transmission member to read an image on the original, original transport means for transporting the original so as to read the image by the read means with the original placed away from the light transmission member, and garbage storage means for storing garbage in the transport passage of the original transported by the original transport means.

That is, the original is transported with the original pressed against the opposed side of the light transmission member in the transport passage of the original by the original transport means and consequently, the original is brought away from the light transmission member at the position of the read means. Accordingly, it is made possible to solve many problems caused by the original read face coming in contact with the light transmission member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, there is shown a preferred embodiment of the invention.

FIG. 1is a drawing to show an image reader incorporating an embodiment of the invention. The image reader includes an original feeder10for transporting originals in order from a stacked original bundle, a scanner70for reading an image by scanning, and a processor80for processing a read image signal.

The original feeder10comprises an original tray11for stacking an original bundle of a plurality of originals and a tray lifter12for moving up and down the original tray11.

It also comprises a naja roll13for transporting an original on the original tray11moved up by the tray lifter12, a feed roll14for transporting the original transported by the naja roll13further to a downstream point, and a retard roll15for handling the originals supplied by the naja roll13separately one by one. First, an original is fed to a first transport passage31. Along with the first transport passage31, there are a take away roll16for transporting the originals handled separately one by one to a downstream roll, a preregistration roll17for transporting the original further to a downstream roll and making a loop, a registration roll18for restarting rotation in timing after once stopping and supplying the original while performing registration adjustment for an original read section, a platen roll19for assisting in transporting the original being read, and an out roll20for transporting the read original furthermore downstream. The original feeder10also comprises a baffle41for rotating on a supporting point in response to the loop state of the transported original in the first transport passage31. Further, the original feeder10comprises a CIS (Contact Image Sensor)50serving as a second sensor in this embodiment and disposed between the platen roll19and the out roll20.

A second transport passage32and a third transport passage33are provided downstream from the out roll20. The original feeder10comprises a transport passage switch gate42for switching the transport passages, an ejection tray40for stacking the read originals, and a first ejection roll21for ejecting the originals to the ejection tray40. The original feeder10also comprises a fourth transport passage34for switching back the original passed through the third transport passage33, an inverter roll22and an inverter pinch roll23being placed in the fourth transport passage34for actually switching back the original, a fifth transport passage35for again guiding the original switched back by the fourth transport passage34into the first transport passage31comprising the preregistration roll17, etc., a sixth transport passage36for ejecting the original switched back by the fourth transport passage34to the ejection tray40, a second ejection roll24being placed in the sixth transport passage36for transporting the reversed and ejected original to the first ejection roll21, and an exit switch gate43for switching the fifth transport passage35and the sixth transport passage36.

The naja roll13is lifted up and is held in a retreat position in a standby mode. When an original is transported, the naja roll13falls to a nip position (original transport position) and transports the top original on the original tray11. The naja roll13and the feed roll14transport the original by joining of a feed clutch (not shown). The preregistration roll17makes the original lead abut against the registration roll18that is stopped for making a loop. When the loop is made, the original lead caught in the registration roll18is returned to the nip position. When the loop is formed, the baffle41opens with the supporting point as the center and functions so as not to interfere with the original loop. The take away roll16and the preregistration roll17hold the loop during reading. As the loop is formed, the read timing can be adjusted and a skew involved in transporting the original at the read time can be suppressed for enhancing the adjustment function of registration. The registration roll18which is stopped starts to rotate in the read start timing, the original is pressed against second platen glass72B (described later) by the platen roll19, and image data is read from the lower face direction.

At the termination time of reading a single-sided original or at the termination time of simultaneous reading both sides of a double-sided original, the transport passage switch gate42is switched so as to guide the original passed through the out roll20into the second transport passage32and eject the original to the ejection tray40. At the sequential read time of a double-sided original, the transport passage switch gate42is switched so as to guide the original into the third transport passage33to reverse the original. At the sequential read time of a double-sided original, the inverter pinch roll23is retracted with feed clutch (not shown) off and nip is opened for guiding the original into the inverter path (fourth transport passage34). Then, the inverter pinch roll23is nipped for guiding the original to be inverted to the preregistration roll17by the inverter roll22or transporting the original to be reversed and ejected to the second ejection roll24of the sixth transport passage36.

The scanner70may comprise the above described original feeder10and supports the original feeder10on a unit frame71and reads an image of the original transported by the original feeder10. The scanner70comprises on the unit frame71serving as a cabinet, a first platen glass72A for placing the original whose image is to be read in a still state and a second platen glass72B having an opening of light to read the original being transported by the original feeder10.

The scanner70comprises a full-rate carriage73standing still below the second platen glass72B and scanning over the whole of the first platen glass72B for reading an image, and a half-rate carriage75for supplying light provided from the full-rate carriage73to an image coupling section. The full-rate carriage73comprises an illumination lamp74for applying light to an original and a first mirror76A for receiving reflected light from the original. Further, the half-rate carriage75comprises a second mirror76B and a third mirror76C for supplying light provided from the first mirror76A to an image formation section. Further, the scanner70comprises an image formation lens77for optically reducing an optical image provided from the third mirror76C, a CCD (Charge Coupled Device) image sensor78for performing photoelectric conversion of the optical image formed through the image formation lens77, and a drive board79comprising the CCD image sensor78.

An image signal provided by the CCD image sensor78is sent through the drive board79to the processor80.

To read the image of the original placed on the first platen glass72A, the full-rate carriage73and the half-rate carriage75move in the scanning direction (arrow direction) in a 2:1 ratio. At this time, light of the illumination lamp74of the full-rate carriage73is applied to the read side of the original and reflected light from the original is reflected on the first mirror76A, the second mirror76B, and the third mirror76C in order and is guided into the image formation lens77. The light guided into the image formation lens77is formed on the light reception face of the CCD image sensor78. The CCD image sensor78is a one-dimensional sensor for processing one line at a time. Upon completion of reading one line in the line direction (main scanning direction), the full-rate carriage73is moved in the direction orthogonal to the main scanning direction (subscanning direction) and the next line of the original is read. This operation is repeated over the whole original size for completing reading of one page of the original.

On the other hand, the second platen glass72B is made of a transparent glass plate of a long plate-like structure, for example. The original transported by the original feeder10passes through on the top of the second platen glass72B. At this time, the full-rate carriage73and the half-rate carriage75are in a stop state at the positions indicated by the solid lines. First, the reflected light on the first line of the original passed through the platen roll19of the original feeder10is formed on the image formation lens77through the first mirror76A, the second mirror76B, and the third mirror76C, and the image is read by the CCD image sensor78of a first sensor in the embodiment. That is, the one line in the main scanning direction is processed at a time by the CCD image sensor78of a one-dimensional sensor and then the next line in the main scanning direction, of the original transported by the original feeder10is read. After the original lead arrives at the read position on the second platen glass72B, the original passes through the read position on the second platen glass72B. The read of one page over the subscanning direction is now complete.

In the embodiment, at the transport time of the original whose first side is read by the CCD image sensor78on the second platen glass72B as the full-rate carriage73and the half-rate carriage75are stopped, the second side of the original can be read by the CIS50of a second sensor at the same time (which means almost the same original transport time rather than the complete time match). That is, the CCD image sensor78of the first sensor and the CIS50of the second sensor make it possible to read images on both sides of the original as the original is once transported to the transport passage.

FIG. 2is a drawing to describe the read structure using the CIS50. As shown inFIG. 2, the CIS50is placed between the platen roll19and the out roll20. One side (first side) of an original is pressed against the second platen glass72B and the image on the first side is read by the CCD image sensor78. On the other hand, in the CIS50, the image on the other side (second side) is read from the opposed side with respect to the transport passage transporting the original. The CIS50comprises glass51of a light transmission member, LEDs (Light-Emitting Diodes)52for applying light to the second side of the original through the glass51, a SELFOC lens53of a lens array for gathering reflected light from the LEDs52passing through the glass51, and a line sensor54of an image sensor for reading the light gathered through the SELFOC lens53as a contact optical unit. As the line sensor54, a CCD or CMOS sensor, a contact sensor, etc., can be used, and an image of actual width (for example, A4 length width 297 mm) can be read. Since the CIS50reads the image using the SELFOC lens53and the line sensor54without using a reduction optical system, the structure can be simplified, the cabinet can be miniaturized, and the power consumption can be decreased. To read a color image, as the LEDs52, three color LED light sources of R (red), G (green), and B (blue) may be used in combination and as the line sensor54, a set of three rows of sensors for three color of RGB may be used.

For the CIS50to read an image, the transport passage forming the read section is provided with a control member55extended from the cabinet of the CIS50and an abutment member60of an opposed side chute for abutting paper pressed by the control member55. A guide member61is placed downstream from the abutment member60and an opening63is made between the guide member61and the abutment member60. Further, a garbage dump section62for accumulating garbage and dust deposited on the surface of the original is placed at a position contiguous to the opening63, below the guide member61. The control member55and the abutment member60are placed corresponding to the position of the transport passage from the front to the rear of the original feeder10in the direction orthogonal to the transport passage of the original (namely, in the direction from the front to the rear of the original feeder10).

Since the CIS50adopts the SELFOC lens53as the optical image formation lens, the depth of focus (field) is deep.FIG. 3is a drawing to describe the focal depth as lens image formation performance. The figure shows examples of MTF (Modulation Transfer Function) of the lens depth (7.8 Lp/mm) using a reduction optical system of the scanner70, etc., in the embodiment and MTF of the lens depth (6 Lp/mm) using the SELFOC lens53. The term “Lp/mm” is a value indicating how many ladder patterns of black and white exist per mm. The MTF indicates how spatial information (contrast) of a subject is faithfully reproduced from a low frequency band (coarse cells) to a high frequency band (fine cells) as frequency characteristics. The vertical axis inFIG. 3indicates the MTF (%) and the horizontal axis indicates the state 1 mm at a time brought apart from the best pint position on the platen glass, etc., and the state 1 mm at a time brought close to the best pint position.

For example, when an original is read, if MTF 20% or more is a target, to use the scanner70in the embodiment, the scanner comes into given focus and the depth of field can be taken large even about ±4 mm. On the other hand, to use the SELFOC lens53, if MTF 20% or more is a target, the depth of field is narrow as about ±10.3 mm and is about 1/13 or less as compared with the case where the scanner70is used. That is, for the CIS50to read an image in the embodiment, the original read position needs to be placed in a predetermined narrow range.

In the embodiment, the control member55is placed upstream of the original transport passage relative to the read position of the CIS50for pressing the original against the abutment member60for transporting the original, so that the attitude of the original between the platen roll19and the out roll20can be controlled stably. “Paper motion B” indicated by the solid line arrow inFIG. 2indicates motion of paper if the control member55does not exist, and “paper motion A” indicated by the chain double-dashed line arrow indicates motion of paper when the control member55is provided. It can be seen from “paper motion A” that the original is pressed against the abutment member60and is transported. That is, in the image reader comprising the CIS50of the read section of a second side placed between the second platen glass72B (platen roll19) of the read section of a first side and the out roll20, the control member55is placed in the proximity of the CIS50of the optical system for reading the second side to suppress an original position shift until the original rushes into the read section of the first side and is caught in the out roll20. The control member55is placed so that the attitude of the original after being caught in the out roll20is brought close to the position of the original before being caught in the out roll20(height from the CIS50).

Thus, the transported original is read with the CIS50focusing in the state in which the original is pressed against the abutment member60by the control member55, whereby incomplete focusing when the CIS50of shallow depth of field is used is improved. More specifically, the average thickness of paper of original is set to 0.1 mm, for example, and the CIS50focuses (the focal position comes) at the position bringing close by the original thickness (for example, 0.1 mm) from the abutment member60. Accordingly, if the original is transported without sliding the original read side over the glass51, it is made possible to read the second side of the original in a desirable state for the resolution characteristic.

When the original is run, garbage or dirt deposited on the surface of the original may appear as a black line on the image output. That is, if the original is transported in intimate contact with the original transport passage of the glass51of the CIS50, for example, pencil carbon, ink, garbage, dirt, etc., is pressed against the glass face, is rub against the transport passage side surface of the glass51, and is easily deposited thereon. If an image is read and output with the pencil carbon, ink, garbage, dirt, etc., deposited on the glass51(for example, the original is copied), the deposit portion appears as a black line in the original transport direction (subscanning direction), causing image quality trouble to occur. As shown inFIG. 2, the CIS50is disposed above the original transport passage and is placed with the surface of the glass51of the read face pointing downward. For example, if the read face points upward as with the second platen glass72B, for example, the original feeder10is opened from the scanner70and the platen roll19is released from the second platen glass72B, so that the read face can be cleaned easily. However, the CIS50is placed pointing downward and thus the original transport face of the glass51points downward. Even if the original feeder10can be opened, it is difficult to clean the read face. In the embodiment, the original is transported with the original pressed against the abutment member60by the control member55, so that the original is not transported in the state in which the original is in intimate contact with the glass51, as described above. Consequently, depositing ink, garbage, dirt, etc., on the original face on the surface of the glass51can be suppressed and damage of a black line, etc., can be lessened.

Further, the abutment member60shown inFIG. 2is molded by resin such as ABS, and also serves as a positioning member for positioning an original, such as a book original, placed on the first platen glass72A, and the face forming the transport passage guides the original into the read section of the CIS50.

The control member55of a protrusion may have a vertex (convex protrusion) shaped like an ark or shaped like a square and is formed of a mold member such as polyacetal. The optimum shape and material for transporting an original are selected. For example, a polyester film such as Mylar (produced by DuPont) may be rounded to form the control member55. As shown inFIG. 2, the control member55is placed at a position not covering the illumination optical path so as not to interfere with light application of the LED52or reflected light. Further, considering transporting an original about 0.1 mm thick and the positioning function of the read position, preferably the dimension (spacing) between the control member55and the abutment member60is 1 mm or less. If both end parts of the control member55in the direction orthogonal to the original transport direction are made higher than the center for making the dimension between the control member55and the abutment member60at both end parts narrower than that at the center, it is made possible to press the original against the abutment member60in a tight state. For example, letting the height of both end parts be “a” and the height of the center be “a′”, “a” minus “a′” can be set to about 0.5 mm. The abutment projection (convex protrusion) of the control member55is set so as to become a length (width) of 300 mm or more in the direction orthogonal to the original transport direction, for example, to control the transport position shift relative to the original of the maximum original width that can be transported.

Further, in the embodiment, when an original rushes into the guide member61, garbage is scraped up and garbage deposited when the original is run is accumulated in the garbage dump section62through the opening63, whereby the garbage deposition amount on the original again transported with the side reversed, for example, can be decreased. In the embodiment, as described above, the state in which the original is transported with the original pressed against the surface of the glass51is lessened, so that garbage deposition on the glass51is largely lessened as compared with general units. However, garbage, etc., may be deposited on the glass51because of electrostatic attraction, etc., even if noncontact is made. It is hard to completely prevent depositing of light-weight suspended matter of paper dust, flue, etc., for example. To lessen garbage deposition on the surface of the glass51as much as possible, garbage is scraped off from the original by the abutment member60and is accumulated in the garbage dump section62through the opening63, whereby it is made possible to reduce the amount of garbage existing on the transport passage.

As a modification of the embodiment, it is also possible to place a protrusion as shown inFIG. 4on the original transport passage.FIG. 4is a drawing to show a structure for waving an original like a letter S before a second side of the original is read by the CIS50. Here, the abutment member60is formed with an S letter forming protrusion65in the direction orthogonal to the original transport direction. As shown inFIG. 4, the height of the S letter forming protrusion65has a lap of about 0.5 mm with the control member55of the protrusion on the opposed side. Preferably, the lap is 0.5 mm or less considering resistance of original transport. The S letter forming protrusion65and the control member55are used to temporarily wave the original like an S letter, whereby flap of the original when the original rushes into the read position of the CIS50is lessened and when the second side of the original is read by the CIS50using the lens of shallow depth of field, it is made possible to improve the resolution characteristic.

FIG. 5is a block diagram to describe the processor80. The processor80incorporating the embodiment of the invention comprises a signal processing section81for processing image information provided by the sensors (CCD image sensor78and line sensor54) and a control section90for controlling the original feeder10and the scanner70. The signal processing section81comprises an AFE (Analog Front End)82for processing an analog signal, an ADC (Analog to Digital Converter)83for converting the analog signal into a digital signal, and a digital processing section84for performing various types of processing of shading correction, offset correction, etc., for the digital signal. The digital signal processed by the digital processing section84is output to a host system and, for example, is output to a printer as image information.

The control section90comprises an image read control91for controlling the whole of the original feeder10and the scanner70including control of double-side read, control of single-side read, etc., a CCD/CIS control92for controlling the CCD image sensor78of the first sensor and the CIS50of the second sensor, a lamp control93for controlling the LEDs of the CIS50and the illumination lamp74of the full-rate carriage73in read timing, a scan control94for turning on/off a motor in the scanner70for controlling the scan operation with the full-rate carriage73and the half-rate carriage75, and a transport mechanism control95for controlling a motor in the original feeder10and controlling the operation of the rollers, the operation of the feed clutch, the gate switch operation, etc. Control signals are output from the controls to the original feeder10and the scanner70, and the operation control is made possible based on the control signals. The image read control91sets the read mode based on the control signal from the host system, sensor output detected in an automatic selection read function, for example, user's selection, etc., and controls the original feeder10and the scanner70.

In the embodiment, when an image is read as an original is transported by the original feeder10, the original transported via the second platen glass72B to the platen roll19can be read using the scanner70(CCD image sensor78) and can also be read using the CIS50placed in the original feeder10. However, as described above, read of the CCD image sensor78using the mechanism of the scanner70and read using the SELFOC lens53of the CIS50differ in focal depth, and becomes different in resolution characteristic. Particularly, to read a color image of a photo, etc., it becomes difficult to perform color matching in both the reads and the image qualities provided in both the reads become different. Then, for example, a plurality of read modes are provided for making it possible to select the optimum mode for reading a double-side original based on the setup state of the unit, the original type, user's selection, etc.

FIG. 6is a flowchart to show an example of processing executed by the image read control91shown inFIG. 5. The image read control91first determines whether or not the original to be transported is a single-side original (step101). This determination can be made based on selection of the user using a control panel (not shown) placed on the scanner70, sensors (not shown) placed on both sides of the first transport passage31before an image is read, for example, if the automatic selection read function works, etc. A request from the host system, selection of the user through a network, etc., is also possible. If it is determined at step101that the original is a single-side original, single-side read in one pass (only one original transport pass using no reversal pass) is performed (step102). In the single-side read in one pass, either of read of the CCD image sensor78and read of the CIS50may be selected; however, to realize image read of higher image quality, preferably read of the CCD image sensor78is selected. In such a case, the original is placed so that the single-side original portion exists upward on the original tray11and the first page of the original comes on the top of the original tray11, and the original is transported starting at the first page and the pages are read in order.

If it is not determined at step101that the original is a single-side original, namely, if the original is a double-side original, whether or not the original is a monochrome original is determined (step103) based on selection of the user or the automatic selection read function as at step101. Even if the original is a color original, the user may want to read the original in monochrome. Not to perform monochrome read, namely, to perform color read, whether or not importance is placed on the image quality is determined (step104). For example, as for a color image of a color photo, pamphlet, etc., generally importance is placed on the image quality rather than productivity of raising the read speed. The determination is also made based on user's setting, etc. If it is determined at step104that importance is placed on the image quality, double-side read in a reversal pass of a first double-side read mode is executed (step105). That is, both the first and second sides of the original are read by the CCD image sensor78of the first sensor without being read by the CIS50. Accordingly, it is made possible to read both the first and second sides of the original with high image quality using the read means of deep focal depth.

On the other hand, if it is determined at step103that monochrome read is executed or if importance is not much placed on the image quality and is placed on any other factor such as productivity, double-side simultaneous read in one pass using no reversal pass, of a second double-side read mode is executed (step106). For example, although color image output is required at step104, in case of business color in which importance is not placed on delicate tint or in case of plus one color (in addition to black, any other one color of red, blue, etc., is contained), the second double-side read mode is executed. That is, the first side is read by the CCD image sensor78of the first sensor and in the transport passage of the read, the second side is read by the CIS50in the same transport passage. Thus, the need for twice transporting the original to the same read section is eliminated, the original read speed can be increased, and the transport passage is simplified, so that original transport trouble of an original jam, etc., can be suppressed. As described above, “simultaneous read” does not necessarily means time match and means reading of both sides at almost the same time in one pass.

The processing flow shown inFIG. 6can also be simplified in double-side original read. To read a monochrome original the double-side simultaneous read at step106is executed, and to read a color original the original is read in order in a reversal passage at step105. The modes can also be mixed for use in response to the original side type.

As described above in detail, according to the embodiment, when an original is read using the CIS50of a contact optical unit such as a contact image sensor, for example, the control member55containing the convex protrusion, etc., is placed on the original transport passage and the original is pressed against the abutment member60of an opposed side chute for reading the original. That is, the image reader comprises the transport passage for transporting an original, the CIS50for reading an image on the original transported on the transport passage, and the control member55for pressing the transported original against the abutment member60on the opposed side of the transport passage at the read position of the CIS50. The original does not slide on the glass51and is not moved at the read position of the CIS50and is moved with the original abutted against the abutment member60of the chute on the opposed side, and image data is read in sequence. Setting is made so that the best focus is obtained as the read position of the CIS50with the original pressed against the abutment member60. Accordingly, if a contact optical unit of shallow depth of field is used, it is made possible to lessen variations in original positions, and the resolution characteristic can be improved.

The original is transported with the original pressed against the abutment member60of the chute on the opposed side, so that the state in which the original comes in contact with the surface of the glass51of the CIS50can be lessened. Consequently, dirt on the original transport passage surface of the glass51can be suppressed and image quality failure caused by the dirt can be decreased. Particularly, if a technique of focusing on the surface of the glass51and reading an original is adopted, the original face slides on the surface of the glass51and moves and thus ink, etc., is easily deposited. However, according to the embodiment, the original is transported with the original pressed against the abutment member60of the chute on the opposed side by the control member55, so that deposition of ink, etc., can be reduced largely.

Further, in the embodiment, the garbage dump section62is placed on the side of the abutment member60of the chute on the opposed side, and a part of garbage scraped off in the abutment member60is removed from the top of the original transport passage. Accordingly, it is made possible to reduce the amount of garbage existing on the original transport passage and suppress dirt on the glass51, etc.

Thus, according to the invention, the attitude of the transported original can be controlled and dirt deposition on the reader can be lessened.