Abstract:
Image-capturing apparatus meeting demands for high-image resolution and high-speed data capture during both still- and moving-document data-capture modes. Includes: a reading unit having first and second linear photoreceptors arrayed along an data capture sub-scanning direction, a delay circuit delaying output from the first photoreceptor, and an adding circuit adding delayed first-photoreceptor output to second-photoreceptor output; and a scanning unit illuminating from underneath the platen, and shiftable along it to guide linear reflected light from a document to the first and second photoreceptors. During a moving-document data-capture mode, the scanning unit is disposed in a data-capture position established at one edge of the platen to scan a document being conveyed, and when in a still-original data-capture mode, it is shifted from along the platen&#39;s opposite edge toward the one edge thereof to scan a stationary document.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to image-capturing apparatuses that use linear image sensors to perform high-speed, high-quality capture of image information, and that have a still-original data-capture mode for capturing information from documents placed on a platen, and a moving-original data-capture mode for capturing information from documents conveyed from a document conveyance device. 
     2. Description of the Related Art 
     Image-capturing apparatuses installed in copiers, facsimile machines, etc. are of late increasingly being expected to manage both accelerated document-scanning speed and heightened image quality. Document image-data capture at high image quality and with exactitude is possible in practice by slowing the relative speed between the document and the data-capturing means that scans images on the document. On the other hand, if the relative speed is quickened, the level of electric charge output from the image sensors will drop, because the sensors&#39; charge-storing time is shortened, inviting compromised image quality. Thus, the heightened speed and heightened image quality expected of image-capturing apparatuses are conflicting demands. 
     Against this backdrop, as a method to manage both heightened speed and heightened image quality in image data capture, apart from speeding up the data read-out rate at which data is read-out data from CCDs, document scanning by a plurality of scanning lines simultaneously is carried out. (Cf., for example, Japanese Unexamined Pat. App. Pub. No. H11-55474.) 
     The image-capturing apparatus set forth in JP H11-55474 is equipped with a linear sensor exemplarily furnished with two photoreceptors—a first photoreceptor and a second photoreceptor—in a row for capturing image data from documents, and therein is designed to realize high-quality image data acquisition and high-speed image data capture by delaying output from the first photoreceptor using a delay circuit, and by adding the delayed output from the first photoreceptor to output from the second photoreceptor. 
     Thus, the fact that the image-capturing apparatus set forth in JP H11-55474 is configured in such a way that of the two—the first and second—photoreceptors, one—the first photoreceptor—is furnished with a delay circuit means that either the image-capturing unit or the document original must necessarily be shifted in the direction in which the first photoreceptor captures original-document image data, ahead of the second photoreceptor. Put differently, the linear sensor has directionality. 
     Image-capturing apparatuses having an automatic document feeder (hereinafter termed “ADF” for convenience), however, ordinarily have two document-data capture modes—not just a still-document data-capture mode for capturing data from a document original placed on the platen, but also a moving-original data-capture mode as well, for capturing data from conveyed document originals. In an implementation in which the directions in which documents are scanned in these two modes are reversed, adopting the directionalized linear sensor set forth in JP H11-55474 would mean that the delay circuit could be used in only one of either of the data-capture modes. 
     Specifically, an implementation in which a delay circuit can be used in the moving-original data-capture mode will create a situation in which the circuit cannot be used in the still-original data-capture mode; conversely, an implementation in which a delay circuit can be used in the still-original data-capture mode will create a situation in which the circuit cannot be used in the moving-original data-capture mode. Consequently, to date it has not been possible to perform scanning at high speed and with high-image quality in both data-capture modes—the still-original data-capture mode and the moving-original data-capture mode. 
     BRIEF SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to make available, in image-capturing apparatuses on which an ADF is installed, an image-capturing apparatus that meets both the two demands of high-resolution scanning and high-speed scanning, during still-original data-capture mode as well as during moving-original data-capture mode: in both of the document data-capture modes. 
     To achieve this object the present invention provides an image-reading apparatus furnished with: an image-reading unit having a platen on which originals are placed; and an original feeder disposed above the image-reading unit, for conveying the originals, the image-reading apparatus being characterized in that said document conveyance unit is equipped with: a sheet supply tray for carrying originals; conveyance means for conveying the originals form the sheet supply tray while turning the originals over from front to back; and a discharge tray disposed below the sheet supply tray and above the platen, for storing the originals conveyed by the conveyance means, the image-reading unit is equipped with: first and second line-shaped photoreceptors arranged side by side along a sub-scanning direction of image reading; a delay circuit that delays output from the first photoreceptor; a reading unit having an adding circuit that adds output delayed by the delay circuit, from the first photoreceptor and output from the second photoreceptor; a scanner movably supported along the platen to sequentially guide light reflected from the original placed on the platen to the first and second photoreceptors; a drive unit for moving the scanning unit; and a control unit for controlling the reading unit and the drive unit, the control unit controls the drive reading units so as to in the moving-original data-capture mode in which reading of the originals conveyed by said document conveyance unit is performed, stop the scanning unit at the reading position predetermined at a first end of the platen to read the conveyed originals, and controls the reading drive units so as to in the still original reading mode in which reading of the originals placed on the platen is performed, read the originals while moving the scanning unit from a second end of the platen to the first end thereof. 
     In this way, this image-reading apparatus is configured so that when in the still-original data-capture mode, the scanning unit is moved from the second end of the platen to the first end thereof (that is, toward a position where the scanning unit is arranged in the moving-original data-capture mode), in the reverse direction in conventional apparatuses. Therefore, such a configuration makes it possible to manage to increase resolution and to raise reading speed at the same time in both original reading modes, namely the still-original data-capture mode and the moving-original data-capture mode. 
     However, the still-original data-capture mode has two data-capture modes that can be selected. They are the addition data-capture mode that adds the output from the first photoreceptor and the output from the second photoreceptor; and a non-addition data-capture mode that uses only output from either the first or the second photoreceptor. Also, in the addition data-capture mode, the scanning unit is moved from another side of the platen to one side thereof to read a stationary original; in the non-addition data-capture mode, the scanning unit moves from one side of the platen toward another side to read the stationary original. 
     A blocking member for, when a document original is placed on the platen in this image-reading apparatus, the document to butt against edgewise to guide the document to its carrying position is arranged at the second end of the platen. 
     In addition, in this image-reading apparatus, first and second detection means for detecting the presence of the scanning unit are provided at the both ends of the scanning unit movement region. Also, a first standby position of the scanning unit is established at the first end of the platen, and a second scanning-unit standby position is established at the second end of the platen. When in the still-original data-capture mode, the scanning unit is moved toward the second standby position after the original is detected to be placed on the platen. This shortens the time required until the reading of the original starts. Also, when the system is switched to the moving-original data-capture mode, the scanning unit is moved toward the first standby position. 
     A reference member is provided in the image-capturing apparatus to obtain reference values for reading data. The reading unit obtains a first reference value and a second reference value of the reference member via the first and second photoreceptors while the scanning unit is moving toward the other side of the platen. The reading unit detects the size of the original placed on the platen while the scanning unit is moved toward the other side of the platen. 
     Furthermore, the original feeder constituting the image-reading apparatus of the present invention has a detection means for detecting whether the original feeder supported openably with respect to the platen is opened or not; detection of if originals have been placed on the platen is performed by this detection means. 
     Also, detection of an original placed on the platen can also be done by detecting that said document conveyance unit apparatus has been closed after it was opened over the platen. 
     In this way, this image-reading apparatus is configured so that the scanning unit is moved from the second end of the platen to the first end thereof when in the still-original data-capture mode so such a configuration makes it possible to realize managing to increase resolution and to raise reading speed at the same time in both original reading modes, namely the still-original data-capture mode and the moving-original data-capture mode. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a view of the overall configuration of an image-capturing apparatus according to the present invention. 
         FIG. 2  is a block diagram of connection relationships of electrically configured elements that compose a control unit of the image-capturing apparatus  1 . 
         FIG. 3  is an explanatory view of a sensor  307  that composes the photoreceptor unit used in the image-capturing apparatus. 
         FIG. 4  is an example of an internal block diagram of the sensor  307 . 
         FIG. 5  is an explanatory view of an arrangement of the scanning unit  304  in a moving-original data-capture mode and a still-original data-capture mode, and an internal configuration of the scanning unit  304 . 
         FIG. 6  is an explanatory view of operations of the scanning unit  304  in the image-capturing apparatus. 
         FIG. 7  is an operational control flowchart of the scanning unit  304  in the still-original data-capture mode. 
         FIG. 8  is a flowchart to explain operations of the moving-original data-capture mode in the image-capturing apparatus. 
         FIG. 9  is an alternate embodiment of the operational control flowchart of the scanning unit  304  in the still-original data-capture mode. 
         FIG. 10  is an operation control flowchart to explain an alternate embodiment of the still-original data-capture mode and the moving-original data-capture mode according to the present invention. 
         FIG. 11  is a view illustrating the open/close relationship of the ADF  2  with respect to the scanner  3  constituents of an image-reading apparatus of the present invention. 
         FIG. 12  is an explanatory view of a transition of operating states of the sensor (a blue photoreceptor) in the image-capturing apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following will now explain in detail embodiments of the image-capturing apparatus according to the present invention. 
       FIG. 1  shows an example of an overall configuration of the image-capturing apparatus. In  FIG. 1 , the image-capturing apparatus  1  is used as a stand-alone (hereinafter called a scanner) image-capturing device or as a reading unit of an image-forming apparatus such as a copier or the like, and is composed of an ADF  2  that is an original conveyance unit for conveying originals, and a scanner  3  used as an image-capturing unit for reading originals. 
     The ADF  2  is composed of an empty sensor ES that detects the presence of an original on a sheet supply tray  201 ; conveyance means  202  that conveys the original from the sheet supply tray  201 ; a conveyance path  203  that turns over originals conveyed by the conveyance means  202  and guides them downstream; and a discharge tray  204  that stores originals whose images have been read. 
     The conveyance means  202  is composed of: a pick-up roller  210  that sends out, one after another, originals stacked on the sheet feeding tray  201 ; a feed roller  211  that separates individually the originals sent one after another by the pick-up roller  210  and feeds them; a pair of registration rollers  212  that correct any skew in the conveyed originals and convey the originals further downstream along the conveyance path  203 ; a pair of conveyance rollers  213  that conveys the originals toward a window  302 ; a first pair of discharge rollers  214  and a second pair of discharge rollers  215  that convey the read originals toward the discharge tray  204 ; and a motor PM 2  (see  FIG. 2 ) that drives each of these rollers. 
     With this configuration, document originals placed on the sheet feeding tray  201  with surfaces to be read facing upward are sent one after the other by the pick-up roller  210 , and then are separated into single sheets and fed by the feed roller  211 . The originals are conveyed and turned over from front to back by the pair of registration rollers  212  and the pair of conveyance rollers  213 . The images on the originals are then read at the reading window  302  serving as reading unit when in the moving-original data-capture mode. Also, the read original is then discharged to the discharge tray  204  by the first pair of discharge rollers  214  and a second pair of discharge rollers  215  with the read surface of the original facing downward. 
     However, the scanner  3  has a platen  301  supported by a box-shaped frame  300  for placing the original; a second blocking part  311  ( FIG. 6 ) disposed at an edge of the platen  301  for engaging an edge of the original placed on the platen  301 ; the window  302  composed of glass for reading the original conveyed by the ADF  2 ; a scanning unit  304  that supports a lamp  303  for irradiating light onto the original; drive means  315  for moving the scanning unit  304  along the platen  301 ; and an open detection sensor OCS. Also, as shown in  FIG. 6 , a white plate  350  for getting basic data as a reference for the image data is installed in the surface of the back side of a first blocking part  310  that scoops up a leading edge of the original conveyed by the ADF  2 . 
     Also, in addition to the lamp  303 , the scanning unit  304  is furnished with a mirror  305  that reflects light from the original; a lens  306  that converges light from the mirror  305 ; a sensor  307  fastened to a sensor substrate  313 , that reads the light converged by the lens  306 ; and an A/D circuit  54  ( FIG. 2 ) installed on the sensor substrate  313 , that converts electric charges (analog signals) output from the sensor  307  into digital signals. Also, the drive means  315  is composed of general drive members such as the motor MP 1 , gears, and the belt  309  connected to the scanning unit  304 , and the like. 
     Also, the scanning unit  304  is configured to reciprocate along the platen by the drive from the motor PM 1  between a first home position detected by a first home position sensor HS 1 , and a second home position detected by a second home position sensor HS 2 . Also, image signals acquired by the sensor  307  are transferred from the sensor substrate  313  to the main unit substrate  6  via a cable  5 . 
     The ADF  2  can open and close over the platen  301  using a hinge. As shown in  FIG. 11 , the open detection sensor OCS detects whether an opening angle of the ADF  2  and scanning unit  304  is higher than a predetermined angle α. When that opening angle is smaller than angle α, it is determined that the ADF  2  is closed over the scanner. When that opening angle is larger than angle α, it is determined that the ADF  2  is opened over the scanner. 
       FIG. 2  is a block diagram of connection relationships of electrically configured elements that compose a control unit of the image-capturing apparatus  1 . In  FIG. 2 , a CPU 4  (control unit) has via a bus line  50  an inverter  51 , a motor driver  52 , an ADF control unit  53 , a sensor  307 , and an A/D circuit  54 , an image processor  55 , an interface  56 , a start switch  60 , and an operation panel  57  that has a touch panel that enables selection of a data-capture mode such as color/B/W data-capture mode, and high-/low-image quality mode. Also, the image-capturing apparatus  1  is furnished with the first home position sensor HS 1 , and the second home position sensor HS 2 , and is connected to an external device (not shown) such as a copier or the like via the interface  50 . Also, ROM 58  and RAM 59  are connected to the CPU 4 . Programs and fixed data that control the image-capturing apparatus  1  are each stored in predetermined address regions on the ROM 58 ; variable data such as image data, and parameters are temporarily stored in RAM 59 . 
     When reading an original, the CPU 4  drives the inverter  51  to light the lamp  303 , and light from the original irradiated by the lamp  303  incidences into each of photoreceptors RS, GS, BS, and B/W of the sensor  307 . After converted into digital signals in the A/D converter circuit  54 , the analog electric charges generated in each of the photoreceptors are subjected to a correction process such as a line correction and gamma correction in the image processor  55 , and are transferred as image data to the external device via the interface  56 . 
     Also, the CPU 4  moves the scanning unit  304  by driving the motor PM 1  via the motor driver  52  according to the data-capture mode, resolution and magnification. Also, the CPU 4  conveys the original by driving the motor PM 2  via the ADF control unit  53 , and the motor driver  60  according to the data-capture mode, resolution and magnification. 
       FIG. 3  is an explanatory view of a sensor  307  that composes the photoreceptor unit used in the image-capturing apparatus. As shown in  FIG. 3 , the sensor  307  is furnished with 4 line-shaped photoreceptors—that is, one black and white photoreceptor B/W in which a plurality of pixels are linearly arranged, for reading black and white, and three photoreceptors RS, GS, and BS for reading color. A film that allows substantially all light of the visible region of light to pass therethrough is attached to the incidence surface of the black and white receptor B/W. A film that allows only red wavelength light to pass therethrough is attached to the incidence surface of the red photoreceptor RS; a film that allows only green wavelength light to pass therethrough is attached to the incidence surface of the green photoreceptor GS; and a film that allows only blue wavelength light to pass therethrough is attached to the incidence surface of the green photoreceptor BS. Therefore, more light is let in the black and white receptor B/W compared with that in other photoreceptors because incident light is not restricted according to its wavelengths. 
     The photoreceptors of sensor  307  are composed of a first and second photoreceptors arranged parallel in sub-scanning direction; the red photoreceptor RS is composed of the first photoreceptor R 1 , the second photoreceptor R 2 ; the green photoreceptor is composed of first photoreceptor G 1 , and the second photoreceptor G 2 ; the blue photoreceptor is composed of first photoreceptor B 1 , and the second photoreceptor B 2 . The interval between the first photoreceptor and the second photoreceptor is equivalent to one line. Note that the interval between the first and the second photoreceptors in each of the color photoreceptors is equivalent to 12 lines; and the interval between the blue photoreceptor and black and white photoreceptor B/W is equivalent to 11 lines. 
       FIG. 4  is an example of an internal block diagram of the sensor  307 . In  FIG. 4 , a register  701  for transferring odd numbered pixels and a register  702  for transferring even numbered pixels are disposed in both sides of the black and white photoreceptor B/W. 
     Also, a storage register  703  (delay circuit) for temporarily accumulating electric charges equivalent to those in one line, accumulated in the first photoreceptor B 1  to delay the electric charges is disposed outside the first photoreceptor B 1  of the blue photoreceptor BS, a shift register  704  is disposed outside the storage register  703 , and a shift register  705  is disposed outside the second photoreceptor B 2 . As in the photoreceptor BS, also in the photoreceptors GS and RS, storage registers  706 ,  709  (delay circuits) for temporarily accumulating electric charges accumulated in each of the first photoreceptors to delay the electric charges are disposed respectively outside the first photoreceptors G 1 , R 1 , and furthermore shift registers  707 ,  710  are disposed respectively outside the storage registers  706 ,  709 . Additionally, shift registers  708 ,  711  are disposed outside the second photoreceptors G 2 , R 2 . Also, an adding circuit  714  that adds the electric charges from the shift registers  704 ,  705 ; an adding circuit  715  that adds the electric charges from the shift registers  707 ,  708 ; and an adding circuit  716  that adds the electric charges from the shift registers  710 ,  711  are formed. Switch circuits  720 ,  721 ,  722  are formed respectively between the shift register  704  and the adding circuit  714 , between the shift register  707  and the adding circuit  715 , and between the shift register  710  and the adding circuit  716 . It is possible to switch to the addition data-capture mode and the non-addition data-capture mode. Here, the addition data-capture mode is a data-capture mode that adds output from the first photoreceptor G 1  and the second photoreceptor G 2 ; the non-addition data-capture mode is a data-capture mode that uses only output from the first photoreceptor G 1  or the second photoreceptor G 2 . 
     Also, electric charges accumulated in the odd numbered pixels of the black and white photoreceptor B/W are output from the shift register  701 , and the electric charge accumulated by the blue photoreceptor BS can be selectively output by the switch circuit  712 . The electric charge accumulated by the even numbered pixels of the black and white photoreceptor B/W output from the shift register  702 , and the electric charge accumulated by the green photoreceptor GS can be selectively output by the switch circuit  713 . With the black and white data-capture mode, electric charges accumulated by the even and odd numbered pixels of the black and white photoreceptor B/W are output from the shift registers  701 ,  702 ; in color data-capture mode, the electric charges accumulated by the blue photoreceptor BS and the green photoreceptor GS are output. 
     The following will now explain sensor operations using the blue photoreceptor, with reference to  FIG. 12 . 
       FIG. 12  is an explanatory view of a transition of operating states of the sensor (a blue photoreceptor) in the image-capturing apparatus.  FIG. 12(   a ) shows a state where electric charge is accumulated in the photoreceptors B 1  and B 2  (oblique lines), and in the storage register  703  (oblique lines). Here, by inputting a SCG (storage gate pulse) to sensor  307 , the electric charge of the storage register  703  is transferred to the shift register  704 . 
     Also, as shown in  FIG. 12(   b ), when data transfer is ended, the storage register  703  is empty. Next, as shown in  FIG. 12(   c ), when a TDI gate pulse (TDI) and shift gate pulse (SH) are input to the sensor  307 , the electric charge of the first photoreceptor B 1  is transferred to the storage register  703 , and the electric charge of the second photoreceptor B 2  is transferred to the shift register  704 . Also, as shown in  FIG. 12(   b ), by inputting a shift clock Ø after the electric charges are transferred to the shift registers  704 ,  705 , the electric charges of the shift registers  704 ,  705  are transferred to the adding circuit  714 , and the electric charge is added. The explanation provided above relates to the blue photoreceptor, but the operations are the same for the green and red photoreceptors. 
     With such a configuration, electric charge accumulated in the black and white photoreceptor B/W is output in black and white reading mode, and electric charges accumulated in the photoreceptors RS, GS, and BS for color is output in color reading mode. Furthermore, in color reading mode, it is possible to select a high-resolution mode in which delayed electric charge from the first photoreceptor and electric charge from the second photoreceptor are added, and the low-resolution mode in which the delayed electric charge from the first photoreceptor and the electric charge from the second photoreceptor are not added. 
     In this way, the sensor that composes the photoreceptor in the image-capturing apparatus has directionality because it is equipped with storage (delay circuit) to temporarily store the electric charge only at one side of the photoreceptor. In other words, adding outputs from the two photoreceptors to use the added outputs requires arranging the sensor so that the first photoreceptor having the delay circuit reads images before the second photoreceptor reads them. 
       FIG. 5  is an explanatory view of an arrangement of the scanning unit  304  in a moving-original data-capture mode and a still-original data-capture mode, and an internal configuration of the scanning unit  304 . As shown in  FIG. 5 , when in the moving-original data-capture mode in which the original A 1  conveyed by the ADF  2  is read, the scanning unit  304  is disposed in a reading position established beneath the platen  301  alongside one end thereof (left side in  FIG. 5 ). 
     Furthermore, the sensor  307  is installed with respect to the reading lines on the original so that the first photoreceptors (R 1 , G 1 , B 1 ) for color read the original before the second photoreceptor (R 2 , G 2 , and B 2 ) reads it. For that reason, it is possible to accumulate in the storage register  703  (delay circuit) electric charges equivalent to those in one line, from the first photoreceptors R 1 , G 1 , and B 1  to delay the electric charges, and to add the delayed electric charges from the first photoreceptors R 1 , G 1 , and B 1  to electric charges from the second photoreceptors R 2 , G 2  and B 2 . Therefore, when in color data-capture mode, it is possible to attain high-image quality image data because it is possible to obtain twice the electric charge compared to when not using a delay circuit with the same accumulation time. 
     On the other hand, in the image-reading apparatus  1  of the present invention, when in the still-original data-capture mode in which reading of the original A 2  placed on the platen  301  is performed, after the scanning unit  304  is moved in the direction of arrow X 1  in  FIG. 5 , the original placed on the platen  301  is read while the scanning unit  304  is moved from the side of the second end to the side of the first end. 
     As reading of still-original in conventional apparatuses, an attempt to read the original while the scanning unit  304  is moved from the side of the first end (in other words, the side where the scanning unit  304  is arranged when in the still-original data-capture mode) to the side of the second end opposite form that side of the first end under the platen  301  means that the second photoreceptors (R 2 , G 2 , B 2 ) read the original before the first photoreceptors (R 1 , G 1 , B 1 ) reads it. At that time, as in the moving-original data-capture mode, it is not possible to accumulate in the storage register  703  (delay circuit) and delay the electric charges from the first photoreceptors (R 1 , G 1 , B 1 ), and to add the delayed electric charges from the first photoreceptors (R 1 , G 1 , B 1 ) to the electric charge from the second photoreceptor (R 2 , G 2  B 2 ). For that reason, with this image-capturing apparatus, if using the delay circuit with the still-original data-capture mode, the reading is conducted while moving the scanning unit  304  to the other side that is an opposite direction to the arrow X 1  shown in  FIG. 5 , which is different from the prior art. 
     Next, the operations of the scanning unit  304  in the image-capturing apparatus will be explained with reference to  FIGS. 6 and 7 . 
       FIG. 6  is an explanatory view of operations of the scanning unit  304  in the image-capturing apparatus.  FIG. 7  is an operation control flowchart of the scanning unit  304  in the still-original data-capture mode. 
     In  FIG. 6 , when the main image-capturing apparatus power is turned on, initial adjustments such as an image data gain adjustment and the like are implement. Thereafter, the scanning unit  304  enters a stand-by state in which it is stopped at the first standby position P 1 . At that time, the reading line L 1  of the sensor  307  is above the white plate  350 . 
     As shown in  FIGS. 6 and 7 , the open detection sensor OCS detects that the ADF  2  is open (in other words, the angle at which of the ADF  2  opens with respect to the platen  301  is beyond a predetermined angle α) (step S 1  in  FIG. 7 ). When it has been detected that the ADF  2  has been closed again (step S 2 ) (the angle is less than the predetermined angle α), the control unit of the image-capturing apparatus  1  drives the motor PM 1  thereby starting the movement of the scanning unit  304  in the direction of the arrow X 1  (a direction toward the other side of the platen (step S 3 ). In such control in steps S 1  and S 2 , it is determined from the detection of the opening/closing of the ADF  2  that the user bumps an edge of the original into the second blocking part  311  and places the original on the platen  301 . 
     Next, while the scanning unit  304  is being moved, the lamp  303  is lit, and the data (white reference data) of the white plate  350  is acquired (step S 4 ). Acquisition of the white reference data is done by connecting the switch circuits  712 ,  713  shown in  FIG. 4  to the register  701  for transfer of the odd numbered pixels of the black and white photoreceptor B/W and to the register  702  for transfer of the even numbered pixels, and connecting the switch circuits  712 ,  713  to the registers  705 ,  708  of the blue and green photoreceptors BS and GS after acquiring white reference data for the black and white data-capture mode performed by reading the white plate  350  with the black and white photoreceptor B/W, connecting the switch register  720  to the side that connects the shift register  704  and adding circuit  714 , the switch register  721  to the side that connects the shift register  707  and adding circuit  715 , and the switch circuit  722  to the side that connects the shift register  710  and adding circuit  716 , setting the delay circuit, and acquiring the white reference data for the color data-capture mode by reading the white plate  350  with the color photoreceptors RS, GS, and BS. Also, the size of the original on the platen  301  is detected by driving the sensor  307  while the lamp  303  is lit (Step S 5 ). 
     Next, the drive of the motor M 1  is stopped when the second home position sensor HS 2  detects the scanning unit  304 . At this time, the scanning unit  304  is positioned at the second idling position P 2  while being detected by the second home position sensor HS 2  (step S 6 ). The second idling position P 2  is the furthest point in the X 1  direction in the region in which the scanning unit  304  moves, and also is the second home position because the position at which reading of the original is started is determined based on this second idling position detected by the second home position sensor HS 2 . 
     Next, if the start signal from the start button is detected (step S 7 ), the control unit ( FIG. 2 ) drives the motor MP 2  to move the scanning unit  304  in the direction of the arrow X 2  shown in  FIG. 6  (step S 8 ), and drives the sensor  307  to start reading the original from an abutting position P 3  of an original abutting surface  311   a  of the second blocking part  311  (step S 9 ). 
     Here, in the black and white reading mode, the switch circuits  712 ,  713  shown in  FIG. 5  are connected respectively to the register  701  for transferring the odd numbered pixels, and to the register  702  for transferring the even numbered pixels, in the black and white photoreceptor B/W to read the original with the black and white photoreceptor B/W and obtain image data for the black and white reading mode. 
     Also, in the color data-capture mode, the switch circuits  712 ,  713  connect to the registers  705 ,  708  of the blue photoreceptor BS and the green photoreceptor GS, the switch circuit  720  connects to the side that connects the shift register  704  and adding circuit, the switch circuit  721  connects to the side that connects the shift register  707  and adding circuit  715 , and the switch circuit  722  connects to the side that connects the shift register  710  and adding circuit  716 , and set to use the delay circuit, the switch circuit  720  is connected to shift register  705  side, the switch circuit  721  is connected to the shift register  708  side, the switch circuit  722  is connected to the shift register  711  side, set to use the delay circuit, and acquire image data for the color data-capture mode by reading the original using the color photoreceptor RS, GS and BS. Note that it is necessary for the movement speed from the abutting position P 3  of the scanning unit  304  to be a speed that corresponds to original resolution and magnification so the distance from the second idling position P 2  to the abutting position P 3  is set to an adequate length for the scanning unit  304  to reach its maximum reading speed at the abutting position P 3  when it first accelerates after the second idling position P 2 . 
     Next, when the reading line L 1  has reached the document edge along the first blocking part  310  (once the reading line L has traveled the length of the document), reading is terminated, and the scanning unit  304  is moved to the first standby position P 1  and the motor PM 1  is stopped (step S 10 ). Here, during the movement from the original reading ending position to the first standby position P 1 , it is acceptable for the movement to be at a speed faster than the reading speed. 
     In this way, if the status of the ADF  2  (being open or closed) is detected, moving the scanning unit in a direction toward the second end of the platen ADF  2  to shift the scanning unit to a position that is closer to the original reading starting position (the original abutting position) enables shortening the time required until the original reading starts in the still-original data-capture mode. Particularly in this embodiment, it is possible to shorten the time until the start of reading in the still-original data-capture mode by having the scanning unit standby at the second standby position P 2  until the reading start signal (command) is detected. 
     In this image-capturing apparatus  1 , the processing time for image data is shortened, and the movement of the scanning unit is effectively utilized by reading the white plate  350  to acquire basic data before the scanning unit  304  reaches the second idling position P 2 . 
     Note that if the determination is negative at step  2 , control is put into the still-original data-capture mode (step S 13 ) by the start signal (command) and control steps S 3  to  10  set forth in  FIG. 7  are carried out. Also, in the moving-original data-capture mode, the system shifts to the still-original data-capture mode by detecting the status of the ADF (whether opened or closed) and the movement of the scanning unit to the second idling position P 2  started, but it is possible to shift to the still-original data-capture mode and execute steps S 3  to  10  shown in  FIG. 7 , by detecting that the ADF  2  is open as indicated by the dotted lines in  FIG. 7 . 
       FIG. 8  is a flowchart for explaining operations in the moving-original data-capture mode in the image-reading apparatus. When the result is a negative determination at step S 1  shown in  FIG. 7 , the start signal (command) has been detected (step S 11 ), and it is has been detected that the empty sensor ES is ON and an original has been set in the sheet supply tray  201  (step S 12 ), the system shifts to the moving-original data-capture mode. 
     As shown in  FIG. 8 , in the moving-original data-capture mode, first the motor PM 1  is driven, and the scanning unit  304  that is standing by at the first standby position P 1  starts moving (step S 100 ) to the direction of the arrow X 2  in  FIG. 6 . Next, the lamp  303  is lit while the scanning unit  304  is being moved, and the white plate  350  is read (step S 101 ). When the white plate  350  is detected by the first home position sensor HS 1  (step S 102 ), the control device ( FIG. 2 ) of the apparatus stops the motor MP 1  (step S 103 ). At this time, the scanning unit  304  is positioned at the end directed along the arrow X 2  of the region in which the scanning unit  304  moves and is detected by the second home position sensor HS 2 . Next, the motor PM 1  is driven to move the scanning unit  304  in the X 1  direction (step S 104 ) and the scanning unit  304  is stopped at the reading position P 4  (step S 105 ). 
     Note that the reading position P 4  is determined from detection of the first home position sensor HS 1 , as, for example, after the predetermined number of pulses is counted from when the first home position sensor HS 1  is turned off. Also, the ADF  2  motor PM 2  is driven to start conveying the original on the sheet supply tray  201  (step S 106 ), and the sensor  307  is driven to read the original passing over the reading window  302  (step S 107 ). 
     Here, if in the color data-capture mode, images are read using the color photoreceptors RS, GS and BS and the delay circuits; if in the black and white data-capture mode, reading is done using the black and white sensor B/W. When the reading of the original is ended, the scanning unit  304  moves to the first standby position P 1 . 
     As described above, in the still-original data-capture mode, moving the scanning unit in the direction in which the scanning unit heads for the reading position (P 4 ) in the moving-original data-capture mode to read the original placed on the platen enables it reading the original using the delay circuits even in the still-original data-capture mode thereby making it possible to obtain high-quality images. 
     By positioning the scanning unit  304  standby position between the reading position P 4  in the moving-original data-capture mode and the platen  301 , and arranging the white plate  350  there, it is possible to obtain reference data by reading the white plate  350  before reading the original for either mode, so the reading of original data can be performed efficiently. 
     Also, when moving-original data-capture mode this image-reading apparatus is in the moving-original data-capture mode of, after the scanning unit  304  is returned to the first home position detected by the first home position sensor HS 1 , it is moved to the reading position P 4  in the opposite direction (X 1  direction) again. By determining the reading position P 4  based on the detection of the first home position sensor HS 1 , highly precise positioning of the reading position P 4  is possible. However, it is also acceptable to move the scanning unit  304  from the first standby position P 1  to the reading position P 4 . 
       FIG. 9  is an alternate embodiment of the operation control flowchart of the scanning unit  304  in the still-original data-capture mode. 
     With the flow of operational controls shown in  FIG. 7 , the second blocking part  311  is disposed at a platen edge that is on the opposite side of the reading position P 4  of the moving-original data-capture mode. An edge of original is abutted against the gate, to place the original on the platen  301 , so it is acceptable to start reading the original from the abutting position P 3  when in the still-original data-capture mode. 
     On the other hand, in an example of the flow of operational controls shown in  FIG. 9 , an explanation will be made of using the first blocking part  310  disposed on the platen edge of the reading position P 4  side of the platen  301 , as shown in  FIG. 6 , as the second blocking member, and using that abutting surface as a second gate position P 6 . 
     With the flow of operational controls of the scanning unit  304  shown in  FIG. 9 , an original is read using delay circuits and adding circuits while moving the scanning unit  304  in the X 2  direction when in the still-original data-capture mode, but the scanning unit  304  standby position and the reading starting position are different from the example shown in  FIG. 7 . In other words, with the example of the flow of operational control shown in  FIG. 7 , the distance of the second idling position P 2  and abutting position P 3  is set so that the speed of movement of the scanning unit  304  from the abutting position P 3  is adequate even at the maximum speed, and the scanning unit is stopped to standby at the second idling position P 2  until it receives the start command, when in the still-original data-capture mode. 
     On the other hand, with the example of the flow of operational controls shown in  FIG. 9 , the scanning unit standby position is different according to the length of the original and the reading speed. In other words, the reading starting position, the moving speed during reading, and the distance necessary for acceleration to the moving speed are found at step S 5  in  FIG. 9  from the results of detecting the original size, and from the resolution and magnification information to determine the scanning unit  304  standby position and the reading starting position (step S 6 ″) and the scanning unit  304  is moved to the calculated standby position (step S 7 ″). Also, in the same way as the flow of operational controls described in  FIG. 7 , after receiving the reading start command from the start button (step S 8 ), the scanning unit  304  is moved in the X 2  direction (shown in  FIG. 6 ) (step S 9 ), and reading of the original starts from the reading starting position found at step S 6 ″ (step S 10 ). 
       FIG. 10  is an operation control flowchart to explain an alternate embodiment of the still-original data-capture mode and the moving-original data-capture mode according to the present invention. In  FIG. 10 , the reading start command is received by means of the start button (step S 201 ), and when an original is detected to be on the sheet feeding tray with the empty sensor ES being turned ON (step S 202 ), the still-original data-capture mode is established, and the operational controls similar to those shown in  FIG. 8  are carried out. Also, when a negative determination is made, the still-original data-capture mode is established in step S 202 , and the following flow of operational control is started. 
     In  FIG. 10 , it is determined whether the user has selected the color data-capture mode (step S 203 ). If that determination is negative, it is determined that the high-quality image mode has been selected (step S 204 ). When the high-quality image mode is selected, the switch circuits  712 ,  713  are connected respectively to the register  705  of the blue photoreceptor BS, and to the register  708  of the green photoreceptor GS, and after setting the switch circuits  720 ,  721 ,  722  in the same way as described above, to the mode to use the delay circuits (step S 205 ), the motor PM 1  is driven to start moving the scanning unit  304  stopped at the first standby position P 1  to the direction of arrow X 1  (step S 206 ). Next, the data (white reference data) of the white plate  350  is acquired (step S 207 ) by lighting the lamp  303  and moving the scanning unit  304 . 
     Also, the size of the original is detected while the movement of the scanning unit  304  in the X 1  direction is continued, and when the scanning unit  304  is detected by the second home position sensor HS 2  (step S 208 ), the motor M 1  is stopped so the scanning unit  304  is stopped at the second idling position P 2  (step S 209 ). Next, the motor M 1  is driven in reverse to start moving the scanning unit  304  from the second idling position P 2  to the X 2  direction (step S 210 ) to read the original images while the scanning unit  304  is moving (step S 211 ). In this case, reading is performed while using the delay and adding circuits. When the reading of the original is ended, the motor M 1  is stopped, and the scanning unit  304  stops at the first standby position P 1  (Step S 212 ). 
     In a negative determination at step S 204 , if the low-image quality mode is selected, the switch circuit  712 ,  713  are connected to the registers  705 ,  708  side of the blue photoreceptor BS and the green photoreceptor GS, the switch circuits  720 ,  721 ,  722  are opened to set not to use the delay circuits (to set to use only output from the shift registers  705 ,  708 ,  711 ) (step S 213 ). Next, the motor MP 1  is driven to start moving the scanning unit  304  standing by at the first standby position P 1  to the direction of arrow X 2  in  FIG. 6  (step S 214 ), and when the first home position sensor HS 1  was detected (step S 215 ), the motor PM 1  is stopped (step S 216 ). At this time the scanning unit  304  is positioned at the first standby position P 1 . 
     Next, the motor PM 1  is driven to move the scanning unit  304  in the X 1  direction (step S 217 ), the lamp  303  is lit while the scanning unit  304  is being moved (step S 218 ), and the white plate  350  is read to start reading the original from the second standby position P 5  (step S 219 ). When the reading of the original is ended, the scanning unit  304  is moved in the X 2  direction (step S 220 ), and is returned to the first standby position P 1  to be stopped (step S 221 ). 
     When the determination is negative at step S 203 , and if the black and white reading mode is selected, the switch circuits  712 ,  713  are connected to the register  701  that transfers the odd numbered pixels of the black and white photoreceptor B/W and to the register  702  that transfers the even numbered pixels to set so that the output electric charge from the black and white photoreceptor B/W is output. The subsequent step is the same as steps S 214  to  221 . Therefore, explanations of these steps will be omitted. 
     Note that in each of above explanations of the moving-original data-capture mode, examples in which the delay circuits/adding circuits are employed are provided. However, it is acceptable not to provide them when the low-resolution data-capture mode is selected, or not using the delay circuits/adding circuits when the low-resolution data-capture mode or high-resolution data-capture mode is selected. 
     In the explanation above, storage registers as delay circuits were provided between the first photoreceptors of the reading sensors and the shift registers, but the locations for the delay circuits are not limited there to, if they are able to temporarily store and delay electric charges. Also, the delay circuits and adding circuits each targeted analog signals (electric charges), but it is also acceptable to delay and add digital signals. Also, one line of the electric charge is delayed and added, but it is also acceptable to delay and add electric charges of more than one line. In such a case, the sensor will increase in size for that increase in the number of lines, but it will be possible to acquire good, high-resolution images with the same reading time (accumulation time).