Abstract:
A sheet feeding scanner has its contact image sensor hanging pivotally on two side walls and is capable of turning with respect to the axis of the pivots. The contact image sensor presses against a driving roller by gravity and/or by a spring. A sheet of paper is sandwiched between the contact image sensor and the roller. The contact image sensor can be disengaged from the roller by an external release rod. The paper is removed when the release rod is actuated or by pulling the paper hard.

Description:
This application is a continuation-in-part, of application No. 08/696,569, filed Aug. 6, 1996, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a scanner, in particular to a paper feeding mechanism for the scanner. 
     Scanners are widely used today for reproducing an image digitally. In conventional technology, a contact image sensor and a roller of the scanner are installed on different structures. The main reason for using separate structures is that when the document is clamped, the paper clamped between the image contact sensor and the roller can be released. 
     A conventional contact image sensor, CIS contains a light source, a focusing lens and a sensor. It is an image reading head. Due to its small exterior dimensions and light weight, it is widely used in facsimile machines and paper-feeding image scanners. Today, small size and light weight are the direction where the industry devotes it development effort. 
     FIG. 1 shows the conventional design of a sheet feeding scanner. A contact sensor  1  has a glass window  1   d . A document  3  to be scanned is pressure-fed by the roller  2  to engage the contact image sensor  1  and is scanned. The roller  2  is pressed against the document  1   d  by the radial arm  21  from an axis  9 . The contact image sensor  1  has a spring  8   a , which pushes the contact image sensor  1  against the roller  2  along the groove  7 . Document  3  is fed through window  1   d  by the rotation of the roller and scanned by the contact image sensor  1 . 
     Such products are sold commercially. For example, Microtek Inc. of Taiwan produces a sheet feeding scanner, under the trade name, Page Wiz; and an American company, Visioneer, produces a paper feeding scanner, under the trade name Paperport, etc. The length, width and height dimensions are 30 cm×10.5 cm×5.5 cm and 30 cm×6.3 cm×9.0 cm, respectively. Since most paper feeding scanner are designed for use with standard A4 size papers, the width is usually 30 cm. Therefore, the size of the scanner is mostly determined by the cross-sectional dimension (perpendicular to the width) of the scanner, and the development effort of most companies is concentrated in reducing the cross-sectional dimensional area. For the afore-mentioned products, the cross-sectional areas are 10.5 cm×5.5 cm and 6.3 cm×9.0 cm, respectively. It is highly desirable to further reduce this cross-sectional area. In U.S. Pat. No. 5,621,544, Ogura et. al disclosed an image reading device, wherein a reading unit and a convey unit are integrally mounted on a U-shaped support unit. The reading unit and the convey unit can be disengaged by turning a semicircular cam against a spring which pushes the reading unit against the convey unit. Both the U-shaped support unit and the cam occupy more space in the housing and are undesirable. 
     SUMMARY 
     An object of this invention is to unify the contact image sensor and the roller of a scanner in a single structure. Another object of this invention is to reduce the weight and volume of the structure. Still another object of this invention is to reduce the cost of the scanner. 
     These objects are achieved in this invention by unifying the contact image sensor and the roller of a scanner in one structure. The contact image sensor is pivoted on two sidewalls along an axis and is capable of turning with respect to that axis. This contact image sensor is pressed against a roller with a paper sandwiched between the contact image sensor and the roller. The pressure is exerted by the gravity of the contact image sensor which hangs above the roller and/or by a spring. The contact image sensor can be disengaged from the roller by pushing a release rod against the contact image sensor. The paper can be extracted when the release rod is actuated, or simply by pulling the paper harder. With this structure, the contact image sensor and the roller can be mounted on the same side walls, thus saving space. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     FIG. 1 shows a prior art scanner. 
     FIG. 2 shows the 3-dimensional view of the present invention. 
     FIG. 3 shows the different components of the present invention. 
     FIG. 4A shows one embodiment of the present using a push rod action for releasing the document to be scanned; 
     FIG. 4B shows another embodiment of the present invention using the push rod action for releasing the document to be scanned. 
     FIG. 5 shows the frame of the scanner for the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 2 shows the 3-dimensional view of the scanning mechanism, base on the present invention. The contact image sensor  1 ′ and the roller  2 ′ are mounted on two sidewalls  4  and  5  through two separate axes. Two walls are mounted directly on the frame of the scanner linked by grooves formed inside surface of the frame, as contrasted from the prior art disclosed in U.S. Pat. No. 5,621,544 using a U-shaped subassmebly t mount the reading unit (the contact image sensor) and the convey unit (roller) which occupy more space in the scanner housing. Referring FIG. 3, the contact image sensor  1 ′ has one end  1   h ′ pivoted on sidewall  4  through pin  4   a . The other end of the contact image sensor is pivoted on side wall  5  through pin  5   a . The pin  5   a  is extended outside the sidewall  5 . One end  4   b  of the roller  2 ′ is pivoted to the sidewall  4  and the other end  5   b  is pivoted to the sidewall  5 . The end  5   b  is geared to a driving mechanism  52  to turn the roller  2 ′. 
     One feature of this invention is that the contact image sensor  1 ′ and the roller  2 ′ are both mounted on the side walls  4  and  5 . In prior art, the contact image sensor and the roller are mounted on separate side walls in order to separate the contact image sensor and the roller for dispatching the clamped paper. 
     A second feature of this invention is that the contact image sensor is pivoted on the sidewalls  4  and  5  by a pin, thus allowing the contact image sensor to rotate with respect to the axis of the pin. In the prior art, the contact image sensor cannot rotate and is recessed in a groove ( 7  in FIG.  1 ), which only allows movement within the confines of the groove against a spring action ( 8   a  in FIG.  1 ). 
     A third feature of this present invention is that the document release rod  11  straddles over the end  5   b  of the roller  2 ′ as shown in FIG.  3 . One end of the release rod  11  is in contact with the contact image sensor  1 ′ as shown in FIG.  4 . When the release rod  11  is pressed at the other end, the release rod  11  exerts pressure on the contact image sensor  1 ′ to rotate slightly with respect to the axes  4   a  and  5   a . This slight rotation disengages the contact image sensor  1 ′ from the roller  2 ′. Thus, the document  3 ′ clamped between the contact image sensor  1 ′ and the roller  2 ′ is released. In the prior art, there has been neither any release rod nor such action. In practical design, it is possible to implement the action without a release rod by pulling harder the document clamped between the contact image sensor  1 ′ and the roller  2 ′. 
     A fourth feature of the present invention is the elimination of the groove  7  in the prior art shown in FIG.  1 . 
     A fifth feature of the present invention is the elimination of the pressure arm  1  for the roller  2  in the prior art shown in FIG.  1 . 
     A sixth feature of the present invention is the elimination of disengagement mechanism of the contact image sensor  1  and the roller  2  in the prior art shown in FIG. 1 by rotating the arm  21  with respect to axis  9 . In the first embodiment of the present invention as shown in FIG. 2, the release rod  11  can produce a narrow gap between the contact image sensor  1 ′ and the roller  2 ′ to release the document  3 ′. In the second embodiment of the present invention, no release rod is used the document  3 ′ is pulled hard to be released. 
     FIG. 4 a  shows the release action of the first embodiment of the present invention. One end of the document release rod  11  shown in FIG. 3 is for a user to press. The other end of the release rod is in contact with the contact image sensor  1 ′. A spring  8   a ′ is pressed against the opposite side of the contact image sensor  1 ′. When the release rod is not actuated, the spring  8   a ′ presses the contact image sensor  1 ′ to engage the roller  2 ′. The disengagement is made by the push rod in a linear wedging motion so that positive action can be effected without using a side cam regardless of the tilt of the scanner and space is saved as compared to any mechanism which requires 2-dimensional (cam) motion and 2-dimensional space such as the disclosed by Ogura in U.S. Pat. No. 5,621,544. 
     FIG. 4 b  shows the release action of the second embodiment of the present invention. On end of the document release rod  11  as shown in FIG. 3 is for a user to press. The other end of the release rod is in contact with the contact image sensor  1 ′. The contact image sensor  1 ′ is placed over the roller  2 ′. The weight of the contact image sensor  1 ′ with or without an additional weight  8   b  on the contact image sensor  1 ′ is sufficient to cause the contact image sensor  1 ′, which hangs at the axis  5   a , to engage the roller  2 ′ by gravity. 
     FIG. 5 shows the frame of the complete scanner. A frame  90  houses an input slot  92  to guide and feed the document  3 ′ for scanning. Another output slot  96  is used to guide the document already scanned. A feedthrough hole  94  is provided for the release rod to protrude and be pushed. Inside the frame  90  are the contact image sensor  1 ′, the roller  2 ′, the sidewalls  4 ,  5  of the driving mechanism  52  described in the previous paragraphs, and a printed circuit board  10  which mounts the electronic circuits for controlling the operation of the scanner. The frame has a back cover  8 , on which is mounted the spring  8   a ′ for pushing the contact image sensor  1 ′ with sufficient force to engage the roller  2 ′. 
     The foregoing description is two embodiments of the present invention. Any modifications using the same principle of pivoting the contact image sensor to engage the driving roller and mounting the roller in the same frame are all within the scope of this invention.