Abstract:
An image reading apparatus equipped with an image reading apparatus unit (B) provided a platen ( 33 ) and reading means ( 31 ) that reads an original, a document feeder (A) provided conveyance paths (P 1 ), (P 2 ), and (P 3 ) leading from a sheet supply tray ( 1 ) to a discharge tray ( 34 ) via the platen ( 33 ) on a top surface of the image reading apparatus unit (B), a hinge device ( 12 ) that openably connects the document feeder (A) to a top surface of the image reading apparatus unit (B), wherein an image reading unit ( 50 ) is equipped in the document feeder (A), and the image reading unit ( 50 ) is integrally connected to a support member fastened to the hinge device ( 12 ). This configuration prevents mispositioning or misalignment of a reading line of the image reading unit ( 50 ) caused by repeated opening and closing of the document feeder (A).

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention, involving image reading (scanning) apparatuses for reading image data in photocopiers, facsimile machines, computer networks, etc., relates to devices that scan both sides of an original-image document in the course of conveying the document from a sheet supply tray to a discharge tray. 
     2. Description of the Related Art 
     Generally, this kind of image reading apparatus is widely used as a device that scans original images in the course of conveying a document original sheet from a sheet supply tray to a discharge tray. Duplex scanning apparatuses that read images on one side of an original sheet in the course of the sheet&#39;s conveyance, then read images on the reverse side of the original are sheet are known. For the scanning means in such devices, photoelectric conversion elements are used, while line-sensors in reduction optics and contact-type line sensors in 1× optics are also known. 
     For example, Japanese Unexamined Pat. App. Pub. No. 2001-42578 proposes an apparatus configuration whereby an original sheet is conveyed from a sheet supply tray at an upper unit to a first platen at a lower unit, the upper and lower units being vertically disposed, and proposes providing a second platen in a path leading the original sheet to a discharge tray after images have been read at the first platen. A reduction-optics sensor is disposed at the first platen, and a 1×-optics sensor is disposed at the second platen. An original platen that is different from the first platen is provided in the lower unit to accommodate books or other types of thick or bulky originals. Ordinarily, these kinds of upper and lower units are configured to be able to open using a hinge unit. Specifically, the upper unit opens to allow an original to be placed on the platen. 
     Conventionally, if first and second image reading sensors are disposed in a path that guides the original sheet from the sheet supply tray to the discharge tray, a fixing means, such as screws, is used to mount the 1×-optics contact sensor to a sheet conveyance guide. The focal depth is shallower for contact sensors than it is for reduction-optics sensors, so mispositioning of the contact sensor causes improper focusing of the original and blurring of read images. Conventionally, however, when such sensors are fastened by screws to the guide plate on which original are conveyed, they can come out of their proper positioning by the repeated opening and closing of the apparatus. Furthermore, if it is difficult to remove dust or dirt adhering to image reading surface (platen) of the sensor, the sensor unit must be removed from the apparatus and cleaned. Conventionally, there was the possibility of scratching the reading surface when removing the sensor unit. Therefore, considerable skill and close attentiveness have been required in detaching the sensor unit. 
     Thus, the present invention provides an image reading apparatus that allows the easy mounting and removal of a sensor unit in an original sheet conveyance path with little or no mispositioning of the sensor unit at the upper unit side when the upper unit is repeatedly opened and closed over the bottom unit with the sensor unit mounted. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an image reading apparatus equipped with a platen for placing an original for reading images thereon; and reading means that reads one side of an original placed on the platen. The image reading apparatus is composed of a document feeder equipped with a sheet supply tray that stacks originals; a discharge tray that stores read originals; a conveyance path leading from the sheet supply tray to the discharge tray via the platen; and a hinge device that openably connects the document feeder to the image reading apparatus. Also provided are a reading unit disposed in the document feeder that reads another side of the original, and support means that supports the reading unit, the support means being integrally connected to the hinge device. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a sectional view of an image reading apparatus according to the present invention; 
         FIG. 2  is an expanded sectional view of the area around a sensor unit in the image reading apparatus; 
         FIG. 3  is a view of the mounted sensor unit; 
         FIG. 4  is a sectional view to explain accessing the sensor unit; 
         FIG. 5  is an overall perspective view of an arrangement of a hinge device of a document feeder; and 
         FIG. 6  is a sectional view of the essential portion of another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention will now be explained with reference to the drawings provided.  FIG. 1  is a sectional view of the overall image reading apparatus according to the present invention. 
     The invention shown in  FIG. 1  is composed of a lower unit B equipped with a first platen  33 , and of an upper unit A installed to the lower unit B. An original platen  30  adjacent to first platen  33 , and a carriage  31  that is a first image reading means that reciprocates along both platens  30  and  33  are equipped. The carriage  31  is supported on a guide rail to move along the original platen  30  to scan the original sheet set on the original platen  30 ; the carriage is also fastened to a tract member, such as a transmission belt, connected to a drive motor (not shown). 
     A photoelectric conversion means  32 , such as a CCD, is equipped on the carriage  31 ; an optical means, such as a focusing lens that forms original images, and mirrors, and a light source lamp are equipped on the photoelectric conversion means  32 . Therefore, to read the image data, light from the light source on the carriage  31  irradiated onto the first platen  33 , and the original on the original platen  30 , is reflected by mirrors, formed into an image on the photoelectric conversion means  32  by the focusing lens, and then converted to electrical signals. The focusing lens is composed of an ordinary reducing imaging lens. Note that it is also acceptable not to install the photoelectric conversion means  32  and focusing lens on the carriage  31 , as described above, but at a bottom of the casing  35 . Also, it is acceptable to install them in a separate, second carriage different to the carriage mounted with the light source. 
     The upper unit A equipped with the sheet supply tray  1  and discharge tray  34  is installed above the original platen  33  and first platen  30  of the bottom unit B. A substantially U-shaped conveyance path that guides an original sheet from the sheet supply tray  1  to the discharge tray  34  via the first platen  33  is formed in the upper unit A as described below. The conveyance path is composed of a paper feed path P 1  that guides an original sheet from the sheet supply tray  1  to the first platen  33 ; a straight conveyance path P 2  that guides the original sheet from the first platen  33  to the discharge tray  34 ; and a cycling path P 4  that recycles the conveyed original sheet, its leading edge fed into the discharge tray  34 , to switch the original back to guide it again through the paper feed path P 1 . Essentially, this process enables the system to read a second side of the original. The conveyance path P 2  is formed to be substantially straight; a second image reading means (hereinafter referred to as a contact sensor unit)  50  is disposed equipped with a second platen  51  for reading a backside (the second side) of a switched back original sheet. 
     A pickup roller  2  is disposed near the sheet supply tray  1  supported by a rocking arm  21  to move between an idle position above the tray, and an actuating position where the pickup roller  2  engages an uppermost sheet on the tray. A gate stopper  22 , is disposed to be moved by an actuating solenoid (not shown) between an aligning position (see the state in  FIG. 1 ) to engage and align the leading edge of the sheet, and a retracted position retracted away from the tray. The rocking arm  21  is supported by a rotating shaft  5  connected to a paper feed unit drive motor M 1 , interposed by a spring clutch. The spring clutch loosens when the rotating shaft  5  is rotated in the paper feed direction thereby moving the rocking arm  21  from the idle position to the actuating position, and becomes taught when the rotating shaft  5  is rotated in the reverse paper feed direction thereby rockingly rotate the rocking arm  21  in the counterclockwise direction of  FIG. 1 . It is held at the idle position shown in  FIG. 1  by a stopper (not shown). Furthermore, rotational force of the rotating shaft  5  in the paper feed direction is transmitted to the pickup roller  2  by a transmission belt, or the like. 
     A paper feed roller means  3   a  is supported on the rotating shaft  5 , interposed by a one-way clutch. Separating means, such as a separating roller  3   b  or the like, is pressed against the paper feed roller means  3   a  to separate original sheets picked up or drawn out of the sheet supply tray  1  by the pickup roller  2  into a single sheet to allow the original sheet to be conveyed further downstream by the paper feed roller means  3   a . A paper feed guide  25  that forms the paper feed path P 1  is formed at a downstream side of the paper feed roller means  3   a  by an upper paper guide Pg 1  and lower paper guide Pg 2 . A registration roller means  4  composed of a drive roller  4   a  and a follower roller  4   b  is disposed in the paper feed path P 1 ; a registration sensor Sr 1  is disposed at an upstream side thereof. A read roller  36  is disposed upstream side near the first platen  33 . Therefore, the leading edge of the original sheet from the paper feed means  3   a  is aligned by the registration roller means  4 , and the original sheet is further conveyed to the downstream read roller  36 . The registration roller means  4  is connected to the paper feed unit drive motor M 1  that rotates in a direct away from the paper feed roller means  3   a . The rotating shaft  5  is rotatingly driven by the forward drive of the motor M 1 ; the registration roller means  4  is rotatingly driven by the reverse drive of that motor. 
     The read roller  36  supplies the original sheet to the first platen  33  at a constant speed at a signal from the sheet sensor Sr 2  disposed near an upstream side of that roller. The speed of the read roller  36  is specified by the control unit of the lower unit B for type of original (color or B/W), and the variable magnification. A backup roller  37  is disposed at the reading position of the first platen  33 , and a first conveyance roller  38  is disposed downstream. These convey the original sheet at the same speed as the read roller  36 . The read roller  36 , backup roller  37 , and first conveyance roller  38  are connected to a conveyance unit drive motor M 2  along with the discharge roller  40 . The second platen  51  is disposed in the straight conveyance path P 2  leading from the first platen  33  to the discharge tray  34 . The first conveyance roller  38  and second conveyance roller  39  are each composed of a pair of opposing pressing rollers at predetermined distances in the conveyance path P 2 . The straight conveyance path P 2  is composed of an upper paper guide Pg 3  and a lower paper guide Pg 4 . 
     A discharge path P 3  is provided downstream of the straight conveyance path P 2 ; a path switching flapper  41  near an upstream side of the discharge outlet guides an original sheet either from the discharge path P 3  to the discharge tray  34  or to the cycling path P 4  using an actuating solenoid (not shown). A feed roller  42  and an upper paper guide Pg 5  and a lower paper guide Pg 6  that compose a path are provided in the cycling path P 4 . The feed roller  42  is connected to the conveyance unit drive motor M 2 . Therefore, an original sheet conveyed from the first platen  33  is guided to the second platen  51  via the straight conveyance path P 2 , and then from the discharge path P 3  to the discharge tray  34  for storage. While the original sheet is nipped by the discharge roller  40 , the conveyance unit drive motor M 2  drives in reverse thereby causing the original sheet to be guided by the path switching flapper  41  into the cycling path P 4 . The feed roller  42  conveys the original sheet to the registration roller means  4  in the paper feed path P 1 . 
     Note that the cycling path P 4  is disposed in the apparatus shown in the drawings to guide an original to the paper feed path P 1  without being read at the second platen  51 , so that its backside (the second side) can be read at the first platen  33 . Thus, it is possible to avoid reading images using the contact sensor unit (second image reading means) which has comparatively poor reading accuracy when reading color images or fine images. An original cover  43  of the platen  30  is mounted to the upper unit. 
       FIG. 2  is an expanded sectional view of the area around the sensor unit in the image reading apparatus. The contact sensor unit (hereinafter referred to as the sensor unit)  50  has an LED array  53 , a Selfoc lens array  55 , and sensor array  54  built-in to a plastic frame  52 , and is composed as a unit to cover the second platen  51 , as shown in the sectional view of  FIG. 2 . Normally, a Selfoc lens array  55  is composed of an 1× imaging lens whose focal depth is shallow compared to a reducing imaging lens. Therefore, a structure that opposingly disposes a backup roller  44  that touches the original sheet against the second platen  51  is adopted. This structure is described below. 
     The sensor unit  50  is fit into holder member  56 s formed in the apparatus frame. The holder members  56  are composed of substantially U-shaped channeled steel material perpendicular to the direction of original sheet conveyance in the straight conveyance path P 2 . For that reason, recesses  56   a ,  56   b  that compose guide rails are formed in the opposing side walls of the holder member  56 . Projections  52   a ,  52   b  that conform to the pair of projections  56   a ,  56   b  are formed on the sensor unit  50 . 
     The projections  52   a ,  52   b  of the sensor unit  50  mate with the recesses  56   a ,  56   b  by being inserted from one end (the front side of  FIG. 2 ) to the other (toward the back side of the same drawing) of the holder member. This sets a height position h with the lower paper guide Pg 4  that composes the straight conveyance path P 2 . An output cable  54   a  from the sensor array  54  of the sensor unit  50  is connected by a connector that has a detachable socket  54   b , and is pulled out from an opening  56   c  formed in the holder member  56 . 
     A lower paper guide Pg 4  that forms a predetermined gap with the platen (second platen)  51  of the sensor unit, is disposed in the straight conveyance path P 2 , and the backup roller  44  that opposes the reading unit of the platen (second platen)  51  is fixed to the paper guide Pg 4 . The backup roller  44  is formed by a free roller that follows the movement of the original sheet. The upper paper guide Pg 2  of the straight conveyance path P 2  is formed of the platen (second platen)  51  of the sensor unit  50  and guides (guide members)  56   d ,  56   e  formed into the holder member  56 . 
     In addition to bending and forming channel steel, the guides  56   d ,  56   e  can also be integrally formed by mounting different members than the channel members. Because the guides  56   d ,  56   e  (guide members) are integrally formed in the holder member  56  to guide the original sheet to the platen (the second platen)  51 , it is possible to maintain a fixed positional relationship between the platen (second platen)  51  of the sensor unit  50  and the guides (guide members)  56   d ,  56   e . Essentially, no level difference is generated between the two. 
       FIG. 3  is a view of the mounted sensor unit. The holder member  56  is mounted between the side plate frames  11   a ,  11   b , as shown in  FIG. 3 . The apparatus shown in the drawing is composed of monocoque structure that mounts the components to the synthetic outer case  10 . Side plate frames  11   a ,  11   b  (opposing each other at the front and back sides of  FIG. 1 ) are disposed on the outer case  10  to ensure mechanical strength. The paper feed drive motor M 1 , described below, and a transmission mechanism are mounted to the side plate frames  11   a ,  11   b . The holder member  56  is composed as a stay member (a reinforcing member that connects both side plates) on the mutually opposing side plate frames  11   a ,  11   b.    
     The holder member  56  is fastened to the front and back side plate frames  11   a ,  11   b  by fixing screw  11   c  and boss  11   d , for example, and the outer case  10  is fastened to the side plate frames  11   a ,  11   b  by screws. The sensor unit  50  is inserted from a front side of the apparatus and supported (the left side of  FIG. 3 ) on the holder member  56 . One side of a hinge unit  12   a  is mounted to a rear side (the right side of  FIG. 3 ) of the holder member  56 ; the other side of the hinge unit  12   a  is mounted to the lower unit B. As shown in  FIG. 3 , the hinge unit  12   a  is composed of a first mounting member  13   b  and a second mounting member  13   c  mutually connected by a hinge shaft  13   a , and a compression spring  13   d  disposed between both mounting members. The first mounting member  13   b  is mounted to the top surface wall of the bottom unit B. A second mounting member  13   c  is mounted to the holder member  56 . 
     Therefore, the holder member  56  is openably mounted to the bottom unit B by the hinge unit  12   a  with the side plate frames  11   a ,  11   b  and outer case  10  supported. Note that an auxiliary hinge unit  12   b  is mounted to the side plate frame rear side  11   b , as shown in the overall perspective view of  FIG. 5 . In the same way as hinge unit  12   a , the auxiliary hinge unit  12   b  is a comparatively simple structure without a compression spring; it rotatably connects the upper unit A and lower unit B by a hinge shaft. In this way, the hinge unit  12   a  supports a great deal of the apparatus weight, and the auxiliary hinge unit  12   b  simply rotatably connects both the upper and lower units A and B. 
     Also, the drive motor M 1  that rotating drives the pickup roller  2 , paper feed roller means  3   a  and registration roller means  4 , and the transmission mechanism are provided at the apparatus rear side plate frame  11   b.    
     Detaching the sensor unit  50  will now be explained with reference to  FIG. 4 .  FIG. 4  is a sectional view to explain detaching the sensor unit. As shown in  FIG. 5 , the outer case  10  is composed to separate the front cover  10   a , the rear cover  10   b  and the paper feed cover  10   c . The front cover  10   a  is detachable in the direction of the arrow in that drawing; the paper feed cover  10   c  rotates in the direction of the arrow in that drawing.  FIG. 4  shows the state when the front cover  10   a  is removed and the paper feed cover  10   c  is rotated open. In  FIG. 4 , the upper paper guide Pg 1  that composes the paper feed path P 1  is integrally configured to the front cover  10   a  to open the paper feed path P 1 . The lower paper guide Pg 6  that composes the cycling path P 4  opens to the state shown in the drawing around the rotating shaft of the registration roller means  4 . The upper paper guide Pg 5  is also rotatable to the state shown in the drawing, around the shaft  16 . 
     Each guide member opens, as shown in  FIG. 4 , so the socket  54   b  and the fixing screw of the sensor unit  50  can be removed if required. The sensor unit  50  can then be pulled to the front side of the apparatus shown in  FIG. 4 . By pulling the sensor unit  50  out along the recesses  56   a ,  56   b  formed to a rail shape in the holder member  56 , it is possible to remove it from the apparatus. When removed, there is no danger of hitting and damaging the platen (second platen)  51 . This unit can also be remounted to the apparatus along the rail-shaped recesses  56   a ,  56   b  without damaging the platen, while maintaining the positional relationship with the back roller  44 . 
     The invention provides the lower unit equipped with the first platen, and the upper unit equipped with the second platen. Also, a sectional, substantially U-shaped holder member is disposed in a perpendicular direction to original sheet conveyance on the upper unit. Because the second image reading means (sensor unit) is formed with projections on one member, and recesses on the other, the sensor unit is matingly mounted into the holder member. Therefore, it is easy to install or remove the sensor unit without damaging the reading surface when detaching the sensor unit. 
     Also, the hinge means is fastened to the holder member, so the upper unit is openably connected to the bottom unit. Therefore, even if the apparatus frame becomes distorted from opening and closing, the position of the sensor unit mounted to the holder member will constantly be accurate and provide stable image readings. 
     Furthermore, a sheet supply tray and discharge tray are both disposed above the bottom unit. A substantially U-shaped conveyance path is disposed leading from the sheet supply tray to the discharge tray leading via the first platen. By disposing a holder member that fastens a hinge means in a path leading from the first platen of the conveyance path to the discharge tray, the weight of drive mechanisms such as drive motors that kick out originals from a tray stacked with original sheets and a sheet supply tray are mutually balanced centering on the holder member and opened by a hinge, so the apparatus is more smaller and more compact. 
     Note that a contact sensor unit  50  equipped with a contact sensor is adopted for the second image reading means, but as shown in  FIG. 6 , it is also acceptable to adopt a reduction-optics sensor unit  70  equipped with a plurality of mirrors  71  and a lens  72 , and photoelectrical conversion means  73 , such as a CCD. 
     Also, a second reading means  50  equipped with a contact sensor is disposed in the conveyance path P 2  downstream of the platen  33 , but as shown in  FIG. 6 , it is also acceptable to dispose a second reading means  70  upstream of a platen  76  to read originals at a first image reading means  75  of the bottom unit. In that case, the stay member  77  is mounted to the hinge device (not shown), and the holder member  78  is integrally fastened to the stay member  77  by screws or the like. Also, a side plate of the apparatus (not shown) is mounted to the stay member  77  and holder member  78 . More specifically, the stay member  77  and holder member  78  are fastened to a hinge device that is substantially integrated. 
     Also, a second image reading means  70  is mounted to the stay member  77 , the holder member  78  and apparatus side plate. Note that in the embodiment shown in  FIG. 6 , the second image reading means (an reduction-optics sensor unit)  70  is configured to be slidably removed from the front side of the apparatus. When second image reading means (the reduction-optics sensor unit)  70  are slid to the front of the apparatus, the stay member  77  and holder member  78  function to guide that the second reading means  70  to a predetermined position along a top surface of the stay member  77 . 
     Thus as described above, the second image reading means  70  is substantially supported by the stay member, the sensor unit will not become mispositioned even if the apparatus frame becomes distorted from repeated opening and closing of the upper unit over the bottom unit, and it is possible to attain accurate and stable image readings.