Abstract:
A new technique is provided to manufacture a CIS module by employing an alignment-plate, a light-guide plate, and a resolution plate. The above plates can be selected to be pre-fabricated into one piece to reduce the number of components for the CIS module. The dimension of resolution definition structures of resolution plate determines the resolution of CIS module and allows only the reflect light from the image with a desired resolution to pass through. Consequently, it alleviates the butting difficulty in the convention butting operation to form a linear sensor array. Also, a signal reading technique is provided to improve the photo-response of the conventional photo-sensing device. Therefore, operation speed is increased and product performance is improved.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to the field of the image sensing technology, particularly in a CIS (Contact Image Sensor) module manufacturing technique, including a technique to improve butting operation in CIS assembly and a technique to enhance reading photo-response of a photo-sensing element.  
         PRIOR TECHNIQUE  
         [0002]    Conventional CIS (Contact Image Sensor) module had the key components which were assembled as shown in FIG. 1 in a cross sectional view in the direction which was perpendicular to the length of the CIS module. On a PCB (Printed Circuits Board) substrate  100 , there was a sensor chip array which was formed by butting IC (Integrated Circuits) sensor chip  101  to a desired length along the direction of the CIS module length. Consequently, the sensor chip array formed a linear sensor array to the desired full CIS module length. Each IC sensor chip  101  had the sensor array  102  which comprised of a series of photo-sensing elements. Conventionally, each of photo-sensing elements was photodiode or photo-transistor which is called CMOS image sensor. Of course, CCD (Charge Coupled Device) was also employed. The spacing from center to center of two neighboring photo-sensing elements determined the resolution of CIS module. Each photo-sensing element was also called pixel. The pixel size was determined by the resolution, which was defined by the number of dots per inch (dpi). For example, 200 dpi resulted in 5 mils pixel size. Other associated electronic circuits block  103  on PCB  100  was to convey an electrical signal to and from IC chip  101 . The sensor array  102  was aligned to the rod lens  105 . The rod lens comprised of an array of optical fibers  105 - 1 , which were placed in sequential order and coated by the optically non-transmitted material  105 - 2  like black resin. Normally, each optical fiber or core of the rod lens  105 - 1  had a diameter much larger than the pixel dimension of the sensor array  102 . A light source  106  had an array of a light-emitting device like LED (Light Emitting Diode) on another substrate  106 - 1  (typically PCB) to emit light  108 - 1  incident upon the image of document  104  through a sealing glass  109  with a uniform intensity along the module length. The image light (or reflective light from image)  108 - 2  passed through the core  105 - 1  of rod lens  105  to the sensor array  102  such that each pixel converted the image light into a photo-signal for further signal processing.  
           [0003]    [0003]FIG. 2 showed the top horizontal view of a linear sensor chip array along the direction of the module length which comprised a series of same IC sensor chip  101 - 1  to  109 - 9 . Each had a sensor array of same photo-sensing elements  102 - 1  to  102 - 9 . There was a spacing  201  between two neighboring IC sensor chip  101  due to the butting operation. It can be seen that there are several drawbacks of the current CIS module manufacturing technique, including  
           [0004]    (1) it is difficult to align IC chips to achieve a straight line of linear sensor array,  
           [0005]    (2) it is difficult to control a uniform spacing between two neighboring sensor IC chips in sensor IC chip array during butting operations because of the equipment operational tolerance, particularly for the high resolution CIS module.  
           [0006]    (3) it is very critical to align sensor array to rod lens. This alignment operation can easily affect the performance from one CIS module to another CIS module.  
           [0007]    It is known that CMOS image sensor has a low sensitivity than CCD. How to improve CMOS sensor detection ability is constantly investigated. This invention will provide a technique to improve CMOS image sensor performance.  
         SUMMARY OF INVENTION  
         [0008]    It is the first object of this invention to provide a technique to eliminate the difficulty of the IC chip butting operation in CIS module assembly.  
           [0009]    It is the second object of this invention to provide a technique that the CIS module resolution is not necessarily determined by the size of the photo-sensing element.  
           [0010]    It is the third object of this invention to provide a technique that a CIS module can be more cost effectively assembled.  
           [0011]    It is the forth object of this invention to provide a technique that different color signals from the same image can be detected simultaneously.  
           [0012]    It is the fifth object of this invention to provide a technique to increase the operation speed of CIS module.  
           [0013]    It is the sixth object of this invention to provide a technique to improve photo-signal reading for a given design of a photo-sensing element. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0014]    All drawings are not to scale, nor in exact shape and dimension, and location. The only purpose of drawings is to demonstrate the operational principle of this invention.  
         [0015]    [0015]FIG. 1 shows the cross sectional view of key components in the conventional CIS module in a direction perpendicular to the CIS module length.  
         [0016]    [0016]FIG. 2 shows the horizontal view of an linear sensor array along the module length direction which is perpendicular to the cross section as shown in FIG. 1.  
         [0017]    [0017]FIG. 3 shows the arrangement of IC sensor chip array, alignment plate, light-guide plate and resolution plate and the cutting cross section along the center of the structures for each component.  
         [0018]    [0018]FIG. 4 explains the operational principle of resolution structures of resolution plate when each of the resolution structures is a cavity.  
         [0019]    [0019]FIG. 5 shows the cross sectional view of CIS module in a direction perpendicular to the CIS module length to demonstrate this invention which does not employ rod lens in CIS module assembly.  
         [0020]    [0020]FIG. 6 shows a photo-signal reading technique in this invention by employing signal storage stages for repeatedly reading signal and reference storage stages which each reference storage stage stores a reference to be subtracted out from a signal to be read at each signal reading operation when the input signal is applied at the non-inverting terminal of operational amplifier.  
         [0021]    [0021]FIG. 7 shows a photo-signal reading technique in this invention by employing signal storage stages for repeatedly reading signal and reference storage stages which each reference storage stage stores a reference to be subtracted out from a signal to be read at each signal reading operation when the input signal is applied at the inverting terminal of operational amplifier.  
         [0022]    [0022]FIG. 8 shows a technique in this invention to improve the photo-response by employing multiple sensor array to repeatedly reading photo-signal of the same image. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0023]    The fundamental operational principle of this invention to improve CIS module assembly is to employ alignment plate, light-guide plate and resolution plate so that the use of rod lens can be avoided. All alignment plate, light-guide plate and resolution plate are made with a material which is light non-transmissible except light-through structures in alignment plate, light-guide structures in light-guide plate and resolution definition structures in resolution plate. The configuration of three components is in such a manner that alignment plate is between sensor IC chip and light-guide plate which is between alignment plate and resolution plate which is between light-guide plate and line image which consists of a desired number of discrete images which are to be detected by a photo-sensing elements in a linear sensor array. Now, refereeing to FIG. 3, a linear sensor array is formed with a series of sensor arrays of photo-sensing elements from the first sensor array of first photo-sensing element  102 - 1  to last photo-sensing element  102 - 9  on first sensor chip  101 - 1  to last sensor array of first photo-sensing element  102 - 1  to last photo-sensing element  102 - 9  on last sensor IC chip  101  - 9 . In FIG. 3, the last sensor IC chip  101 - 9  is placed slightly off a linear line to show the advantages of this technique as described below. Each sensor array is aligned to light-through structures of an alignment plate in such a manner that the first photo-sensing element  102 - 1  of first array in first sensor IC chip  101 - 1  is aligned to first light-through structure  310 - 1  of first alignment plate  301 - 1 , second photo-sensing element  102 - 2  is aligned to second light-through structure  310 - 2  of first alignment plate  301 - 1  to the last photo-sensing element  102 - 9  in first sensor IC chip  101 - 1  is aligned to last light-through structure  310 - 9  of first alignment plate  301 - 1  as shown in double-dot lines. Likewise, the first photo-sensing element  102 - 1  of last array on last sensor IC chip  101 - 9  is aligned to first light-through structure  319 - 1  of last alignment plate  301 - 9 . Second photo-sensing element  102 - 2  is aligned to second light-through structure  319 - 2  of last alignment plate  301 - 9  and the last photo-sensing element  102 - 9  in last sensor IC chip  101 - 9  is aligned to last light-through structure  319 - 9  of last alignment plate  301 - 9 . Similar to last sensor IC  101 - 9 , last alignment plate  301 - 9  is also placed a slightly off linear line in order to align to last sensor array of last IC chip  101 - 9 . This kind of alignment is called one-to-one alignment. Or it is called that the first sensor array  102 - 1  to  102 - 9  of first sensor IC chip  101 - 1  is one-to-one aligned to first light-through structures  310 - 1  to  310 - 9  of first alignment plate  301 - 1 . Likewise, last sensor array  102 - 1  to  102 - 9  of last sensor IC chip  101 - 1  is one-to-one aligned to last light-through structures  319 - 1  to  319 - 9  of last alignment plate  301 - 9 . Or light-through array of light-through structures from first alignment plate  301 - 1  to last alignment plate  301 - 9  is one-to-one aligned to linear sensor array. Light-through structures are one-to-one aligned to light-guide structures. The end of each light-through structure, which is aligned to each photo-sensing element in sensor array is called sensor end of light-through structure. The other end of light-through structure, which is aligned to light-guide structure is called light-guide end of light-through structure. Therefore, light-guide structures have light-through ends, which are aligned to light-through structures and resolution ends which are aligned to resolution-definition structures. Resolution-definition structures have light-guide ends, which are aligned to light-guide structures and image ends which are aligned to a line image. As shown in FIG. 3 the light-guide end of each aligned light-through structure and light-through end of each aligned light-guide structure are attached together at the light-through end of light-guide structure so that first light-guide structure  320 - 1  in light-guide plate  302  and first light-through structure  310 - 1  in first alignment plate  301 - 1  are integrated into a single piece from resolution end  320 - 1 - 2  through light end  320 - 1 - 1  of first light-guide structure  320 - 1  to the attached light-guide end of first light-through structures  310 - 1  in first alignment plate  301 - 1  to sensor end  310 - 1 - 1  of first light-through structure  310 - 1  in first alignment plate  301 - 1  till an aligned light-guide structure  329 - 1  in light-guide plate  302  and first light-through structure  319 - 1  of last alignment plate  301 - 9  are integrated into a single piece from resolution end  329 - 1 - 2  through light-through end  329 - 1 - 1  of an aligned light-guide structure  329 - 1  to the attached light-guide end  319 - 1 - 2  of first light-through structures  319 - 1  to sensor end  319 - 1 - 1  of first light-through structure  319 - 1  in last alignment plate  301 - 9 . Likewise, other pairs of light-guide structure and respective light-through structure are integrated into a single component which is from resolution end of the respective light-guide structure to sensor end of respective light-through structure as shown in FIG. 3. Therefore, light-through structures of each alignment plate can be flexibly one-to-one aligned to respective sensor array. As shown in FIG. 3, the last alignment plate  301 - 9  can be easily aligned to last sensor chip  101 - 9  which is slightly placed off linear line. Now, light-guide array of light-guide structures from first light-guide structure  320 - 1  to last light-guide structure  329 - 9  in light-guide plate  301  is one-to-one aligned to resolution array of resolution-definition structures from first resolution-definition structure  330 - 1  to last resolution-definition structure  330 - 9  in resolution plate  303  as indicated by the double-dot lines in such a manner that first light-guide structure  320 - 1  is aligned to first resolution-definition structure  330 - 1 , second light-guide structure  320 - 2  is aligned to second resolution-definition structure  330 - 2  till last light-guide structure  320 - 9 - 9  is aligned to last resolution-definition structure  330 - 9 . A center-to-center spacing  360  between two neighboring resolution-definition structures is equal to a desired resolution of CIS module. In FIG. 3, both the image end and the light-guide end of each resolution-definition structure from first resolution-definition structure  330 - 1  to last resolution-definition structure  330 - 9  have same center-to-center spacing  360 . If desired, the light-guide end can have a different spacing and a different dimension from the image end so that it can be much easier to manufacture light-guide structures, light-through structures and sensor chips. FIG. 3 shows the case that light-through structures and light-guide structures are attached by the extension of light-through structures by a length  350 . This extension  350  can also be light-guide structures so that light-through structures and are light-guide structures are attached at light-guide ends of light-through structures. Or alignment plate and light-guide plate can be integrated into a single component such that the alignment section is made flexible, for example with plastic material, to be one-to-one aligned to each sensor IC chip. Those who are skillful in the field can easily modify to satisfy each application.  
         [0024]    When rod lens are really desired to employ, line image is focused on image ends of resolution-definition structures. A conventional operation is followed. Since the center-to-center spacing between any two neighboring resolution-definition structures is equal to a desired resolution of CIS module, a reflective light from a discrete image of a desired resolution enters the aligned resolution-definition structure, then through the aligned light-guide structure which guide it to the aligned light-through structure to the aligned photo-sensing element which converts to a photo-signal which is read out for further signal processing.  
         [0025]    When each resolution-definition structure is in cavity structure, the operational principle of the resolution plate  303  can be described in FIG. 4. Only three neighboring resolution definition structures are used in FIG. 4 to explain the operational principle. The left resolution definition structure  330 - 1  is to collect the reflective light from the left image  421  which has the left edge  435  and the right edge  436  on the document  430  which this left resolution structure  330 - 1  is aligned to. The center resolution-definition structure  330 - 2  is to collect the reflective light from the center image  420  which has the left edge  436  and the right edge  437  on the document  430  which the center resolution definition structure  330 - 2  is aligned to. The right resolution definition structure  330 - 3  is to collect the reflective light from the right image  422  which has the left edge  437  and the right edge  438  on the document  430  which the right resolution definition structure  330 - 3  is aligned to. The three images have the same size of the desired resolution. The thickness  429  of the resolution plate  303  is determined by the separate spacing  428  between the resolution plate  303  and the document  430  in such a manner that the right edge  436  of the left image  421 , the bottom right edge of the left resolution definition structure  330 - 1  and the top left edge of the left resolution definition structure  330 - 1  are formed in first right straight line  401 . Likewise, the left edge  435  of the left image  421 , the bottom left edge of the left resolution definition structure  330 - 1  and the top right edge of the left resolution structure  330 - 1  are formed in first left straight line  402 . Similarly, the right edge  437  of the center image  420 , the bottom right edge of the center resolution-definition structure  330 - 2  and the top left edge of the center resolution definition structure  330 - 2  are formed in second right straight line  405 . The left edge  436  of the center image  420 , the bottom left edge of the center resolution definition structure  330 - 2  and the top right edge of the center resolution structure  330 - 2  are formed in second left straight line  406 . The right edge  438  of the right image  422 , the bottom right edge of the right resolution definition structure  330 - 3  and the top left edge of the right resolution-definition structure  330 - 3  are formed in third right straight line  407 . The left edge  437  of the right image  420 , the bottom left edge of the right resolution definition structure  330 - 3  and the top right edge of the right resolution-structure  330 - 3  are formed in third left straight line  408 . The first right straight line  401  and the surface of the document  430  form first right-side angle  411 . The first left straight line  402  and the surface of the document  430  form first left-side angle  412 . The second right straight line  405  and the surface of the document  430  form second right-side angle  415 . The second left straight line  406  and the surface of the document  430  form second left-side angle  416 . The third right straight line  407  and the surface of the document  430  form third right-side angle  417 . The third left straight line  408  and the surface of the document  430  form third left-side angle  418 . Since the resolution plate  303  and the document  430  are parallel, first right-side angle  411 , second right-side angle  415 , and third right-side angle  417  are equal in this example. When desired, resolution-definition structures are not perpendicular to line image, the left-side angle and right-side angle can be different. Likewise, first left-side angle  412 , second left-side angle  416  and third left-side angle  418  are equal. The resolution plate  303  is made with a material which is light non-transmissible. Each surface of cavities  330 - 1 , 330 - 2  and  330 - 3  is made in such a manner that the reflective light is not reflected again. For example, it can be made very rough and not smooth. Therefore, only reflective light from the left image  421  larger than first right-side angle  411  and first left-side angle  412  can pass through left resolution structure  330 - 1 . Likewise, only reflective light from the center image  420  larger than second right-side angle  415  and second left-side angle  416  can pass through center resolution structure  330 - 2 . Only reflective light from the right image  422  larger than third right-side angle  417  and third left-side angle  418  can pass through center resolution structure  330 - 3 . Any reflective light from neighboring image outside a desired image always forms a smaller angle than either left-side or right-side angle of the desired image. Therefore, there is no reflective light from any other neighboring image to pass through the cavity which is aligned to the desired image. For a fixed separate spacing  428 , a desired resolution can be obtained by adjusting the dimension of the cavity of each resolution definition structure and the center-to-center spacing between two neighboring resolution definition structures. For a fixed dimension of the cavity, adjusting the separate spacing  428  and the center-to-center spacing between two neighboring resolution definition structures can obtain a desired resolution.  
         [0026]    [0026]FIG. 5 shows a cross sectional view similar to FIG. 1, but the rod lens  105  is replaced with resolution plate  580 , light-guide plate  560  and alignment plate  550 . As explained in FIG. 4, for an image  500  which has the left edge  501  and the right edge  501 , only the reflective light from the image  500  which has larger anger then defined by right line  511  and left line  510  can travel through the resolution-definition structures  590  to the light-guide structures  570  of the light-guide plate  560  which guide the reflective light to light-through structures  551  of alignment plate  550  to expose the reflective light onto sensor array  102  of sensor chip array  100 . The advantages of this technique include that more arrays of resolution-definition structures can be employed to align to the same image such that these reflective lights enter one light-guide structure to guide these reflective lights incident on same photo-signal element to result in more photo-signal of this photo-sensing element, or a desired color patter is placed on a multiple resolution-definition structures which are aligned to the same image to result in a different color photo-signal simultaneously to increases the operation speed in the color application or multiple photo-signal from multiple linear sensor array of photo-sensing elements can be simultaneously read by employing multiple arrays of resolution-definition structures, light-guide structures and light-through structures to increase the operation speed in a mono color application. Or different color filters are placed or coated on multiple arrays of resolution-definition structures, different color photo-signal can be obtained at same time. Or the resolution plate, the light-guide plate or the alignment plate can be integrated into a single component to simplify the CIS module assembly. For those who are skillful in the field can easily modify it for each desired application.  
         [0027]    In the conventional CIS technology, the photo-signal of each pixel (photo-sensing element) in the sensor (pixel) array is read by applying a read pulse after a desired period of time of exposure to the light to achieve a desired photo-signal level. The exposure time limits the speed of CIS module operation, particularly for the low light level operation. A technique is provided here to enhance reading of the photo-signal with the conventional reading pulse. FIG. 6 shows one preferred embodiment of this invention which employs a reading circuits section which comprises amplifier circuits block, signal block, reference block and output block. An amplifier circuits block comprises operational amplifier  608  which has non-inverting input terminal  609 , inverting input terminal  610  and output terminal  611 , feedback resistor  612  and inverting input resistor  613 . The ratio of feedback resistor  612  to inverting input resistor  613  determines the gain of this amplifier circuits block. In this example, the gain is set equal to 1, i.e., feedback resistor  612  and inverting input resistor  613  have same resistance. Signal block comprises a read signal storage stage and multiple enhanced read signal storage stages. Read signal is defined as when a signal is applied at input terminal, an output signal of operational amplifier  608  at output terminal  611  is a read signal. Therefore, reading photo-signal of a photo-sensing element results in read photo-signal at output terminal  611  of operational  608 . Only two enhanced read signal storage stages are shown in FIG. 6. Each signal storage stage comprises a signal storage switch, signal storage device which is a capacitor in this example, stored signal reading switch and stored signal discharging switch. The stored signal reading switch is connected between non-inverting input terminal  609  and a common connection point of signal storage switch which is connected to output terminal  611  and signal storage capacitor which is connected to a common ground. Therefore, read signal storage stage comprises read signal storage switch  631 , read signal storage capacitor  632 , read signal reading switch  633  and read signal discharging switch  635 . Likewise, first enhanced read signal storage stage comprises first enhanced read signal storage switch  636 , first enhanced read signal storage capacitor  637 , first enhanced read signal reading switch  638  and first enhanced read signal discharging switch  639 . Second enhanced read signal storage stage comprises second enhanced read signal storage switch  651 , second enhanced read signal storage capacitor  652 , second enhanced read signal reading switch  653  and second enhanced read signal discharging switch  655 . Reference block comprises multiple reference storage stages. Each reference storage stage stores a reference to be subtracted out from a signal to be read. Only four reference stages are shown in FIG. 6. Each reference storage stage comprises reference storage switch, reference storage device which is a capacitor in this example and reference reading switch. Therefore, first reference storage stage stores first reference (one reference) to be subtracted out from photo-signal at reading photo-signal operation. Reading photo-signal operation is defined as a photo-signal of a photo-sensing element is applied at input terminal of operational amplifier  608  to result in an output signal which is a read photo-signal at output terminal  611 . First reference storage stage comprises first reference storage switch  615 , first reference storage capacitor  616 , and first reference reading switch  617 . Second reference storage stage stores second reference (other reference) to be subtracted out from read photo-signal which is stored in read signal storage. Second reference storage stage comprises second reference storage switch  618 , second reference storage capacitor  619 , and second reference reading switch  620 . Third reference storage stage stores third reference (another reference) to be subtracted out from first enhanced read photo-signal which is obtained from reading read photo-signal and stored in first enhanced read signal storage stage. Third reference storage stage comprises third reference storage switch  621 , third reference storage capacitor  622 , and third reference reading switch  623 . Fourth reference storage stage stores fourth reference (further another reference) to be subtracted out from second enhanced read photo-signal which is obtained from reading first enhanced read photo-signal and stored in second enhanced read signal storage stage. Fourth reference storage stage comprises fourth reference storage switch  625 , fourth reference storage capacitor  626 , and fourth reference reading switch  627 . In each reference storage stage, reference reading switch is connected between inverting input resistor  613  and a common connection point of reference storage switch which is connected to output terminal  611  and reference storage capacitor which is connected to a common ground as shown in FIG. 6. Output block comprises multiple output stages. Four output stages are shown in FIG. 6. Each output stage comprises an output post and an output switch which is connected between output terminal  611  and output post. First output stage comprises first output switch  660  and first output post  680 . Likewise, second output stage comprises second output switch  661  and second output post  681 . Third output stage comprises third output switch  662  and third output post  682 . Fourth output stage comprises fourth output switch  663  and fourth output post  683 . In this example, first output stage is designed to transfer read photo-signal. Second output stage is designed to transfer first enhanced read photo-signal. Third output stage is designed to transfer second enhanced read photo-signal. Fourth output stage is designed to transfer third enhanced read photo-signal. There is also photo-signal reading switch  606  which is connected between non-inverting terminal and a common line  605  of multiplexing switches which comprises first signal switch  603 , second signal switch  604 . Only two photo-sensing elements of linear sensor array are shown in FIG. 6 to explain the operational principle. The first signal switch  603  is connected between first photo-sensing element  601  and a common line  605 . The second signal switch  604  is connected between second photo-sensing element  602  and a common line  605 .In case that a parallel dump operation is designed to transfer a photo-signal of each photo-sensing element in a linear sensor array to a respective storage device, these signal switch is connected to respective storage device. But the operation described below is still applied.  
         [0028]    Now, the operation of FIG. 6 can be described below. It comprises the steps of:  
         [0029]    (1) storing first reference which is used to be subtracted out from reading a photo-signal of a photo-sensing element by turning on photo-signal reading switch  606  and first reference storage switch  615 . Therefore, first reference from common line  605  to output terminal  611  is stored into first reference storage capacitor  616 ,  
         [0030]    (2) storing read signal noise by turning on photo-signal reading switch  606 , first reference reading switch  617  and read signal storage switch  631 . Therefore, read signal noise is stored into read signal storage capacitor  632 .  
         [0031]    (3) Storing second reference which is used to be subtracted out from reading read signal which is stored in read signal storage capacitor  632  by turning on read signal reading switch  633  and second reference storage switch  618 . Therefore, second reference is stored into second reference storage capacitor  619 .  
         [0032]    (4) storing first enhanced read signal noise by turning on read signal reading switch  633 , second reference reading switch  620  and first enhanced read signal storage switch  636 . Therefore, first enhanced read signal noise is stored into first enhanced read signal storage capacitor  637 .  
         [0033]    (5) Storing third reference which is used to be subtracted out from reading first enhanced read signal which is stored in first enhanced read signal storage capacitor  637  by turning on first enhanced read signal reading switch  638  and third reference storage switch  621 . Therefore, third reference is stored into third reference storage capacitor  622 .  
         [0034]    (6) storing second enhanced read signal noise by turning on first enhanced read signal reading switch  638 , third reference reading switch  623  and second enhanced read signal storage switch  651 . Therefore, second enhanced read signal noise is stored into second enhanced read signal storage capacitor  652 .  
         [0035]    (7) Storing fourth reference which is used to be subtracted out from reading second enhanced read signal which is stored in second enhanced read signal storage capacitor  652  by turning on second enhanced read signal reading switch  653  and fourth reference storage switch  625 . Therefore, fourth reference is stored into fourth reference storage capacitor  626 .  
         [0036]    (8) Discharging all charges in read signal storage capacitor  633 , first enhanced read signal storage capacitor  638  and second enhanced read signal storage capacitor  653  by turning on read signal discharge switch  635 , first enhanced read signal discharge switch  639  and second enhanced read signal discharge switch  655  respectively.  
         [0037]    (9) now, reading photo-signal of photo-sensing elements in linear sensor array sequentially with no light exposure to linear sensor array by first turning on first signal switch  603  of multiplexing switches, photo-signal reading switch  606 ,first reference reading switch  617 , read signal storage switch  631  and first output switch  660 . Therefore, dark signal of first photo-sensing element  601  is sent out to output post  680  and simultaneously stored into read signal storage capacitor  632 .  
         [0038]    (10) reading dark signal by turning on read signal reading switch  633 , second reference reading switch  620 , first enhanced read signal storage switch  636  and second output switch  661  to obtain first enhanced dark signal. Therefore, first enhanced dark signal is sent out to second output post  681  and simultaneously stored into first enhanced read signal storage capacitor  637 .  
         [0039]    (11) reading first enhanced dark signal by turning on first enhanced read signal reading switch  638 , third reference reading switch  623 , second enhanced read signal storage switch  651  and third output switch  662  to obtain second enhanced dark signal. Therefore, second enhanced dark signal is sent out to third output post  682  and simultaneously stored into second enhanced read signal storage capacitor  652 .  
         [0040]    (12) reading second enhanced dark signal by turning on second enhanced read signal reading switch  653 , fourth reference reading switch  627  and fourth output switch  663  to obtain third enhanced dark signal. Therefore, third enhanced dark signal is sent out to fourth output post  683 . This completes reading dark signal of first photo-sensing element.  
         [0041]    (13) discharging all charges in read signal storage capacitor  633 , first enhanced read signal storage capacitor  638  and second enhanced read signal storage capacitor  653  by turning on read signal discharge switch  635 , first enhanced read signal discharge switch  639  and second enhanced read signal discharge switch  655  respectively.  
         [0042]    (14) repeating step  9  to  13  to obtain dark signal, first enhanced dark signal, second enhanced dark signal and third enhanced dark signal of second photo-sensing element  602  and continuing on to complete reading operation for last photo-sensing element in linear sensor array.  
         [0043]    (15) exposing light to linear sensor array at a desired intensity level for a desired period of time.  
         [0044]    (16) now, reading photo-signal of photo-sensing elements in linear sensor array sequentially by first turning on first signal switch  603  of multiplexing switches, photo-signal reading switch  606 , first reference reading switch  617 , read signal storage switch  631  and first output switch  660 . Therefore, light signal which is read photo-signal of first photo-sensing element  601  is sent out to output post  680  and simultaneously stored into read signal storage capacitor  632 .  
         [0045]    (17) reading light signal by turning on read signal reading switch  633 , second reference reading switch  620 , first enhanced read signal storage switch  636  and second output switch  661  to obtain first enhanced light signal. Therefore, first enhanced light signal is sent out to second output post  681  and simultaneously stored into first enhanced read signal storage capacitor  637 .  
         [0046]    (18) reading first enhanced light signal by turning on first enhanced read signal reading switch  638 , third reference reading switch  623 , second enhanced read signal storage switch  651  and third output switch  662  to obtain second enhanced light signal. Therefore, second enhanced light signal is sent out to third output post  682  and simultaneously stored into second enhanced read signal storage capacitor  652 .  
         [0047]    (19) reading second enhanced light signal by turning on second enhanced read signal reading switch  653 , fourth reference reading switch  627  and fourth output switch  663  to obtain third enhanced light signal. Therefore, third enhanced light signal is sent out to fourth output post  683 . This completes reading light signal of first photo-sensing element.  
         [0048]    (20) discharging all charges in read signal storage capacitor  633 , first enhanced read signal storage capacitor  638  and second enhanced read signal storage capacitor  653  by turning on read signal discharge switch  635 , first enhanced read signal discharge switch  639  and second enhanced read signal discharge switch  655  respectively.  
         [0049]    (21) repeating step  16  to  20  to obtain light signal, first enhanced light signal, second enhanced light signal and third enhanced light signal of second photo-sensing element  602  and continuing on to complete reading last photo-sensing element in linear sensor array.  
         [0050]    (22) obtaining photo-response which is equal to light signal minus dark signal, first enhanced photo-response which is equal to first enhanced light signal minus first enhanced dark signal, second enhanced photo-response which is equal to second enhanced light signal minus second enhanced dark signal, third enhanced photo-response which is equal to third enhanced light signal minus third enhanced dark signal.  
         [0051]    (23) obtaining total photo-response which can be one of photo-response, first enhanced photo-response, second enhanced photo-response, third enhanced photo-response, or sum of any selected number of items from photo-response, first enhanced photo-response, second enhanced photo-response and third enhanced photo-response for each photo-sensing element.  
         [0052]    The above process is set up for a case that dark signal, first enhanced dark signal, second enhanced dark signal and third enhanced dark signal are read out for each photo-sensing element to obtain photo-response, first enhanced photo-response, second enhanced photo-response and third enhanced photo-response respectively. Many other methods can be used to obtain photo-response with the use of FIG. 6. For example, dark photo-signal, including first reference in the above process, of each photo-sensing element is stored into each storage capacitor in such a manner that first dark photo-signal of first photo-sensing element is used to be subtracted out from reading first light level of first photo-sensing element to obtain photo-response of first photo-sensing element, Second dark photo-signal of second photo-sensing element is used to be subtracted out from reading second light level of second photo-sensing element to obtain photo-response of second photo-sensing element and continue on to last dark photo-signal of last photo-sensing element is used to be subtracted out from reading last light level of last photo-sensing element to obtain photo-response of last photo-sensing element. Or either first dark signal including first reference, or a mean value of selected number of dark signals which either include or not include first reference is stored into first reference storage stage for reading photo-signal of a photo-sensing element. Those who are skillful in the field can modify the use of a selection of references for each desired application.  
         [0053]    [0053]FIG. 6 shows a preferred embodiment that when a photo-signal of a photo-sensing element is applied at non-inverting input terminal of operational amplifier. This technique can be equally well applied when a photo-signal of a photo-sensing element is applied at inverting input terminal of operational amplifier. It can be described in FIG. 7. Both reference block and signal block are connected between output terminal  611  and inverting input terminal  610 . Only three reference stages and two signal storage stages are as an example to describe the operational principle of this technique shown in FIG. 7. Now, in amplifier circuits block, non-inverting input terminal  609  is connected to a common ground. There is no photo-signal reading switch. Feedback resistor  702  is connected between output terminal  611  and inverting input terminal  610 . An input resistor is connected to inverting input terminal  610  for reading photo-signal and for reading each stored reference in reference block and each stored signal in signal block. Therefore, photo-signal reading input resistor  701  is connected between a common line  605  and inverting input terminal  610 . In reference block, first reference storage stage comprises of first reference storage switch  711  which is connected to output terminal  611 , first reference storage device (capacitor)  712  which is connected to a common ground, first reference reading switch  715  which is connected between a common connection point of first reference storage switch  711  and first reference storage capacitor  712  and first reference input resistor  716  which is connected between inverting input terminal  610  and first reference reading switch  715 . Second reference storage stage comprises of second reference storage switch  721  which is connected to output terminal  611 , second reference storage capacitor  722  which is connected to a common ground, second reference reading switch  725  which is connected between a common connection point of second reference storage switch  721  and second reference storage capacitor  722  and second reference input resistor  726  which is connected between inverting input terminal  610  and second reference reading switch  725 . Third reference storage stage comprises of third reference storage switch  731  which is connected to output terminal  611 , third reference storage capacitor  732  which is connected to a common ground, third reference reading switch  735  which is connected between a common connection point of third reference storage switch  731  and third reference storage capacitor  732  and third reference input resistor  736  which is connected between inverting input terminal  610  and third reference reading switch  735 . In signal block, read signal storage stage comprises of read signal storage switch  751  which is connected to output terminal  611 , read signal storage capacitor  752  which is connected to a common ground, read signal reading switch  755  which is connected between a common connection point of read signal storage switch  751  and read signal storage capacitor  752  and read signal reading input resistor  756  which is connected between inverting terminal  610  and read signal reading switch  755 . First enhanced read signal storage stage comprises of first read signal storage switch  771  which is connected to output terminal  611 , first read signal storage capacitor  772  which is connected to a common ground, first enhanced read signal reading switch  775  which is connected between a common connection point of first enhanced read signal storage switch  771  and first enhanced read signal storage capacitor  772  and first enhanced read signal reading input resistor  776  which is connected between inverting terminal  610  and first enhanced read signal reading switch  775 . Similar to FIG. 6, first reference is subtracted out from photo-signal at reading photo-signal operation. Second reference is subtracted out from read photo-signal at reading read photo-signal operation. Third reference is subtracted out from first enhanced read photo-signal at reading first enhanced read photo-signal operation. Although many method can be applied to run operation of FIG. 7, only one method is described here. The ratio of feedback resistor  702  to each reference reading input resistor  716 , or  726 , or  736  is designed to be equal to 1. Those who are skillful in the field can easily modify to satisfy each desired application. Now, first reference is stored into first reference storage capacitor  712  by turning on first signal switch  603  and first reference storage switch  711 . Second reference is stored into second reference storage capacitor  722  by turning on first signal switch  603 , read signal storage switch  751  and first reference reading switch  715 , followed by turning on read signal reading switch  755  and second reference storage switch  721 . Third reference is stored into third reference storage capacitor  732  by turning on read signal reading switch  755 , second reference reading switch  725 , first enhanced read signal storage switch  771 , followed by turning on first enhanced read signal reading switch  775  and third reference storage switch  731 . After third reference is stored into third reference storage capacitor  732 , both signals in read signal storage capacitor  752  and first enhanced read signal storage capacitor  772  are cleared by turning on read signal storage switch  751  and first enhanced read signal storage switch  771  through low output resistance of operational amplifier  608 . Of course, a discharging switch can be connected across these two capacitors to clear signals. Here, dark photo-signal, including first reference described in FIG. 6, of first photo-sensing element  601  is used as first reference for each photo-sensing element at reading light signal of photo-sensing element. As described in FIG. 6, mean dark photo-signal can be also used as first reference. After linear sensor array of photo-sensing elements is exposed to light at a desired intensity level for a period of time, photo-response of first photo-sensing element is obtained by turning on first signal switch  603 , first reference reading switch  715 , read signal storage switch  751 , and first output switch  761 . Therefore, photo-response of first photo-sensing element is sent out to first output post  781  and simultaneously stored into read signal storage capacitor  752 . Here, photo-response is equal to light signal minus dark signal which is first reference. First enhanced photo-response is obtained by turning on second reference reading switch  725 , first enhanced read signal switch  755 , first enhanced storage switch  771  and second output switch  762 . Therefore, first enhanced photo-response sent out to second output post  782  and simultaneously stored into first enhanced read signal storage capacitor  772 . Second enhanced photo-response is obtained by turning on third reference reading switch  735 , second enhanced read signal switch  775  and third output switch  763 . Therefore, second enhanced photo-response sent out to third output post  783 . Total photo-response can be photo-response, or first enhanced photo-response, or second enhanced photo-response or sum of selected items from photo-response, first enhanced photo-response and second enhanced photo-response. After completion of reading of first photo-sensing element, all charges in read signal storage capacitor  752  and first enhanced read signal storage capacitor  772  are cleared. Then, the same process steps of reading first photo-sensing element are repeated to obtain total photo-response of each photo-sensing element from second photo-sensing element to last photo-sensing element of linear sensor array.  
         [0054]    Another improved technique to obtain photo-response of a photo-sensing element to detect a line image is shown in FIG. 8. It employs multiple linear sensor arrays. Basically, this technique employs 2D-array (2 dimensional array) to improve photo-signal reading of an image in a line image detection application. This technique comprises five sections which are devices section, signal storage device section, initial set-up switch section, signal reading switch section and output section. In device section, it comprises multiple linear sensor arrays, signal switch and output circuit block. Therefore, as shown in FIG. 8, first linear sensor array consists of first photo-sensing element  811 , second photo-sensing element  815  and on to a desired number of photo-sensing elements in first linear sensor array. First signal switch  812  of first linear sensor array is connected between first photo-sensing element  811  and first common line  801 . Likewise, second signal switch  816  of first linear sensor array is connected between second photo-sensing element  815  and first common line  801  and so on for the rest signal switches in first linear sensor array. Of course, the center-to-center spacing between any two neighboring photo-sensing elements is equal to a desired resolution to detect a discrete image in a line image. First common line  801  is connected to first output circuit block  818  which is a typical output reading circuit in conventional CIS module to convey a photo-signal out for a signal processing. Similarly, second linear sensor array consists of first photo-sensing element  821 , second photo-sensing element  825  and on to a desired number of photo-sensing elements in second linear sensor array. First signal switch  822  of second linear sensor array is connected between first photo-sensing element  821  and second common line  802 . Likewise, second signal switch  826  of second linear sensor array is connected between second photo-sensing element  825  and second common line  802  and so on for the rest signal switches in second linear sensor array. Second common line  802  is connected to second output circuit block  828  which is a typical output reading circuit like first output circuit block  818  in conventional CIS module to convey a photo-signal out for a signal processing. It continues on as shown with a dotted line to one before last linear sensor array which consists of first photo-sensing element  831 , second photo-sensing element  835  and on to a desired number of photo-sensing elements in one before last linear sensor array as shown in FIG. 8. First signal switch  832  of one before last linear sensor array is connected between first photo-sensing element  831  and one before last common line  803 . Likewise, second signal switch  836  of second linear sensor array is connected between one before last photo-sensing element  835  and one before last common line  803  and so on for the rest signal switches in one before last linear sensor array. One before last common line  803  is connected to one before last output circuit block  838  which is a typical output reading circuit in conventional CIS module to convey a photo-signal out for further signal processing. Finally, last linear sensor array consists of first photo-sensing element  841 , second photo-sensing element  845  and on to a desired number of photo-sensing elements in last linear sensor array. First signal switch  842  of last linear sensor array is connected between first photo-sensing element  841  and last common line  804 . Likewise, second signal switch  846  of last linear sensor array is connected between second photo-sensing element  835  and last common line  804  and so on for the rest signal switches in last linear sensor array. Last common line  804  is connected to last output circuit block  848  which is a typical output reading circuit in conventional CIS module to convey a photo-signal out for a signal processing. In signal storage device section, there are signal storage switch and signal storage device to store each read photo-signal of a photo-sensing element in multiple linear sensor arrays. This signal storage device can be a simple storage capacitor, any conventional memory device such as DRAM(Dynamic Random Access Memory). SRAM(Static Random Access Memory), EPROM(Electrical Programmable Read Only Memory), EEPROM (Electrical Erasable Read Only Memory), or magnetic storage devices etc. A desired number of signal storage devices form a signal storage array. One signal storage array contains at least the same number of signal storage devices as the number of photo-sensing elements of a linear sensor array whose photo-signals are to be stored into this signal storage array. A desired number of signal storage array form a signal storage group. One signal storage group contains at least the same number of signal storage arrays as the number of linear sensor array whose photo-signals of photo-sensing elements are to be stored into respective signal storage devices of respective signal storage array. The number of signal storage groups is at least equal to the number of linear sensor arrays in multiple linear sensor arrays. The number of signal storage groups and the number of storage devices in each signal storage array can be different. As shown in FIG. 8, first signal storage group  861  consists of one signal storage array  861 - 1  which consists of a series of signal storage device from first signal storage device  861 - 1 - 1  to last signal storage device  861 - 1 -n. First signal storage switch  862 - 1  is connected between first signal storage device  861 - 1 - 1  in first signal storage array  861 - 1  and first signal reading line  862 . It continues on to last signal storage switch  862 -n which is connected between last signal storage device  861 - 1 -n in first signal storage array  861 - 1  and first signal reading line  862 . Second signal storage group  871  consists of first signal storage array  871 - 1  and second signal storage array  871 - 2 . First signal storage array  871 - 1  consists of a series of signal storage device from first signal storage device  871 - 1 - 1  to last signal storage device  871 - 1 -n. First signal storage switch  872 - 1  is connected between first signal storage device  871 - 1 - 1  in first signal storage array  871 - 1  and first signal reading line  872 . It continues on to last signal storage switch  872 -n which is connected between last signal storage device  871 - 1 -n in first signal storage array  871 - 1  and first signal reading line  872 . Likewise, second signal storage array  871 - 2  consists of a series of signal storage device from first signal storage device  871 - 2 - 1  to last signal storage device  871 - 2 -n. First signal storage switch  873 - 1  is connected between first signal storage device  871 - 2 - 1  in second signal storage array  871 - 2  and second signal reading line  873 . It continues on as shown with a dotted line to last signal storage switch  873 -n which is connected between last signal storage device  871 - 2 -n in second signal storage array  871 - 2  and second signal reading line  873 . It continues on to one before last signal storage group  881  as shown in FIG. 8. One before last signal storage group  881  consists of multiple signal storage arrays from first signal storage array  881 - 1  to one before last signal storage array  881 -(m- 1 ). Similar to first signal storage group  861  and second signal storage group  871 , first signal storage array  881 - 1  consists of a series of signal storage devices from first signal storage device  881 - 1 - 1  to last signals storage device  881 - 1 -n. The first signal switch  882 - 1  of first signal storage array  881 - 1  is connected between first signal storage device  881 - 1 - 1  and first signal reading line  882  of one before last signal storage group  881  and on to last signal switch  882 -n which is connected between last signal storage device  881 - 1 -n and fist signal reading line  882 . As shown in FIG. 8, it continues to two before last signal storage array  881 -(m- 2 ) which consists of a series of signal storage devices from first signal storage device  881 -(m- 2 )- 1  to last signals storage device  881 -(m- 2 )-n. In two before last signal storage array  88   1 -(m- 2 ), first signal storage switch  881 -(m- 2 )- 1  is connected between first signal storage device  881 -(m- 2 )- 1  and two before last signal reading line  883  and on to last signal storage switch  881 -(m- 2 )-n which is connected between last signal storage device  881 -(m- 2 )-n and two before last signal reading line  883 . One before last signal storage array  881 -(m- 1 ) consists of a series of signal storage devices from first signal storage device  881 -(m- 1 )- 1  to last signals storage device  881 -(m- 1 )-n. In one before last signal storage array  881 -(m- 1 ), first signal storage switch  881 -(m- 1 )- 1  is connected between first signal storage device  88   1 -(m- 1 )- 1  and one before last signal reading line  884  and on to last signal storage switch  88   1 -(m- 1 )-n which is connected between last signal storage device  88   1 -(m- 1 )-n and one before last signal reading line  883 . Finally, last signal storage group  891  consists of other multiple signal storage arrays from first signal storage array  891 - 1  to last signal storage array  891 -(m- 1 ). Similar to the description of one before last signal storage group  881 , first signal storage array  891 - 1  consist of a series of signal storage devices from first signal storage device  891 - 1 - 1  to last signal storage device  891 - 1 -n. First signal storage switch  890 - 1  of first signal storage array  891 - 1  is connected between first signal storage device  891 - 1 - 1  and first signal reading line  890  and on to last signal storage switch  890 -n which is connected between last signal storage device  891 - 1 -n and first signal reading line  890 . Second signal storage array  891 - 2  consist of a series of signal storage devices from first signal storage device  891 - 2 - 1  to last signal storage device  891 - 2 -n. First signal storage switch  892 - 1  of second signal storage array  891 - 2  is connected between first signal storage device  891 - 2 - 1  and second signal reading line  892  and on to last signal storage switch  892 -n which is connected between last signal storage device  891 - 2 -n and second signal reading line  892 . It continues on as shown with dotted line to one before last signal storage array  891 -(m- 1 ) which consists of a series of signal storage devices from first signal storage device  89   1 -(m- 1 )- 1  to last signal storage device  891 -(m- 1 )-n. First signal storage switch  893 - 1  of one before last signal storage array  891 -(m- 1 ) is connected between first signal storage device  891 -(m- 1 )- 1  and one before last signal reading line  892  and on to last signal storage switch  893 -n which is connected between last signal storage device  891 -(m- 1 )-n and one before last signal reading line  893 . Finally, last signal storage array  891 -m consists of a series of signal storage devices from first signal storage device  891 -m- 1  to last signal storage device  891 -m-n. First signal storage switch  894 - 1  of last signal storage array  891 -m is connected between first signal storage device  891 -m- 1  and last signal reading line  894  and on to last signal storage switch  894 -n which is connected between last signal storage device  891 -m-n and last signal reading line  894 . In output section, there is output switch which is connected between signal reading line and output post. Therefore, first output switch  865  is connected between first signal reading line  862  and first output post  865 - 1  in first signal storage group  861 . In second signal storage group, first output switch  875  is connected between first signal reading line  872  and first output post  875 - 1  and second output switch  876  is connected between second signal reading line  873  and second output post  876 - 1 . Likewise, in one before last signal storage group  881 , first output switch  885  is connected between first signal reading line  882  and first output post  885 - 1  and so on to one before last output switch  886  which is connected between one before last signal reading line  883  and one before last output post  886 - 1 . In last signal storage group  891 , first output switch  895  is connected between first signal reading line  890  and first output post  895 - 1 , second output switch  896  is connected between second signal reading line  892  and second output post  896 - 1  and so on to one before last output switch  897  which is connected between one before last signal reading line  893  and one before last output post  897 - 1 .Finally, last output switch  898  is connected between last signal reading line  894  and last output post  898 - 1 . In initial set-up switch section, there is an initial set-up switch which is connected between signal line from output circuit block in device section and signal reading line of signal storage array in signal storage group. An initial set-up switch is called first initial set-up switch when it is connected to first signal line  819  which is connected to first output circuit block  818 . Therefore, an initial set-up switch is called second initial set-up switch when it is connected to second signal line  829  which is connected to second output circuit block  828 . An initial set-up switch is called one before last initial set-up switch when it is connected to one before last signal line  839  which is connected to one before last output circuit block  838  and an initial set-up switch is called last initial set-up switch when it is connected to last signal line  849  which is connected to last output circuit block  848 . Therefore, an initial set-up switch is connected in such a manner that there is one first initial set-up switch which is connected to one signal reading line from first signal storage group  861  to last signal storage group  891 , there is one second initial set-up switch which is connected to one different signal reading line from second signal storage group  871  to last signal storage group  891 , there is one third initial set-up switch which is connected to one other different signal reading line from one before last signal storage group  881  to last signal storage group  891  and there is one fourth initial set-up switch which is connected to one another different signal reading line in last signal storage group  891 . Consequently, one of first initial set-up switch  801 - 1  is connected between first signal line  819  and first signal reading line  862  in first signal storage group  861 . Other one of first initial set-up switch  801 - 2  is connected between first signal line  819  and second signal reading line  873  in second signal storage group  871 . Another one of first initial set-up switch  801 - 3  is connected between first signal line  819  and one before last signal reading line  884  in one before last signal storage group  881 . Further another one of first initial set-up switch  801 - 4  is connected between first signal line  819  and last signal reading line  894  in last signal storage group  891 . One of second initial set-up switch  802 - 1  is connected between second signal line  829  and first signal reading line  872  in second signal storage group  871 . Other one of second initial set-up switch  802 - 2  is connected between second signal line  829  and two before last signal reading line  883  in one before last signal storage group  881 . Another one of second initial set-up switch  802 - 3  is connected between second signal line  829  and one before last signal reading line  894  in last signal storage group  891 . One of one before last initial set-up switch  803 - 1  is connected between one before last signal line  839  and first signal reading line  882  in one before last signal storage group  881 . Other one of one before last initial set-up switch  803 - 2  is connected between one before last signal line  839  and second signal reading line  892  in last signal storage group  891 . One of last initial set-up switch  804 - 1  is connected between last signal line  849  and first signal reading line  890  in last signal storage group  891 .  
         [0055]    In signal reading switch section, similar to initial set-up switch, a signal reading switch is called first signal reading switch when it is connected to first signal line  819 . A signal reading switch is called second signal reading switch when it is connected to second signal line  829 . A signal reading switch is called one before last signal reading switch when it is connected to one before last signal line  839 . A signal reading switch is called last signal reading switch when it is connected to last signal line  849 . Now, first initial set-up switch is connected to every signal reading line in last signal storage group  891 . Second initial set-up switch is connected to every signal reading line in one before last signal storage group  881 . One before last initial set-up switch is connected to every signal reading line second storage group  871 . Last initial set-up switch is connected to every signal reading line in first signal storage group  861 . Therefore, in last signal storage group  891 , one of first signal reading switch  801 - 5  is connected between first signal line  819  and first signal reading line  890 . Other one of first signal reading switch  801 - 6  is connected between first signal line  819  and second signal reading line  892 . It continues on as shown with dotted line to another one of first signal reading switch  801 - 7  which is connected between first signal line  819  and one before last signal reading line  893 . Further another one of first signal reading switch  801 - 8  is connected between first signal line  819  and last signal reading line  894 . In one before last signal storage group  881 , one of second signal reading switch  802 - 5  is connected between second signal line  829  and first signal reading line  882 . It continues on to other one of second signal reading switch  802 - 7  which is connected between second signal line  829  and two before last signal reading line  883 . Another one of second signal reading switch  802 - 8  is connected between second signal line  829  and one before last signal reading line  884 . It continues on to second signal storage group  871 , one of one before last signal reading switch  803 - 5  is connected between one before last signal line  839  and first signal reading line  872 . Other one of one before last signal reading switch  802 - 6  is connected between one before last signal line  839  and second signal reading line  873 . In first signal storage group  861 , last signal reading switch  804 - 5  is connected between last signal line  849  and first signal reading line  862 .  
         [0056]    The operational principle of FIG. 8 can be described. A reading process consists of two steps to detect to reflective light from a discrete image of a desired resolution with a photo-sensing element to result in a photo-signal of a photo-sensing element. First step is to set up an initial condition to be ready for repeatedly reading photo-signal of a discrete image with a multiple arrays of photo-sensing elements. Second step is to read out each photo-signal from each photo-sensing element of each linear sensor array in multiple linear arrays for the same discrete image. Now, First line image which comprises of a series discrete image from first discrete image to last discrete image is one-to-one aligned to first linear sensor array such that first discrete image is aligned to first photo-sensing element  811 , second discrete image is aligned to second photo-sensing element  812  and so on to last discrete image is aligned to last photo-sensing element of first linear sensor array. First step is to set up initial conditions to prepare detection of first line image by reading out photo-signals which are read with multiple linear arrays and stored into multiple signal storage groups. In the following description, all switches are off, if not indicated to turn it on.  
         [0057]    First step comprises the steps of:  
         [0058]    1. reading photo-signals of first linear sensor array and storing into first signal storage group  861  after first line image is one-to-one aligned to first linear sensor array by turning on:  
         [0059]    (a) one of first initial set-up switch  801 - 1  and  
         [0060]    (b) sequentially from first signal switch  812 , second signal switch  816  to last signal switch of first linear sensor array and synchronizing sequentially from first signal storage switch  861 - 1 - 1  to last signal storage switch  861 - 1 -n of first signal storage array  861 - 1  in first signal storage group  861  in such a manner that first signal switch  812  and first signal storage switch  862 - 1  are turned on at same time to store photo-signal of first photo-sensing element  811  into first signal storage device  861 - 1 - 1 , followed by turning on second signal switch  816  and second signal storage switch  862 - 2  to store photo-signal of second photo-sensing element  815  into second signal storage device  861 - 1 - 2  and so on to store to store photo-signal of last photo-sensing element of first linear sensor array into last signal storage device  861 - 1 -n. This concludes the storage of each photo-signal of first linear sensor array into respective each signal storage device of first signal storage array  861 - 1 . This signal storage process is called reading and storing photo-signals of first linear sensor array into first signal storage array. Of course, the order of signal switches is not necessarily needed to be in the sequence as described. It can be other order sequence as long as there is one-to-one correspondent pair between signal switch and signal reading switch.  
         [0061]    2. reading photo-signals of first linear sensor array and second linear sensor array and storing into second signal storage group  871  after first line image is one-to-one aligned to second linear sensor array and second line image is one-to-one aligned to first linear sensor array by turning on:  
         [0062]    (a) other one of first initial set-up switch  801 - 2  and one of second initial set-up switch  802 - 1  and  
         [0063]    (b) sequentially from first signal switch  812 , second signal switch  816  to last signal switch of first linear sensor array and synchronizing sequentially from first signal storage switch  873 - 1  to last signal storage switch  873 -n of second signal storage array  871 - 2  in second signal storage group  871  in such a manner that first signal switch  812  and first signal storage switch  873 - 1  are turned on at same time to store photo-signal of first photo-sensing element  811  into first signal storage device  871 - 2 - 1 , followed by turning on second signal switch  816  and second signal storage switch  873 - 2  to store photo-signal of second photo-sensing element  815  into second signal storage device  871 - 2 - 2  and so on to store photo-signal of last photo-sensing element of first linear sensor array into last signal storage device  871 - 2 -n. This concludes the storage of each photo-signal of first linear sensor array into respective signal storage device of second signal storage array  871 - 2 .  
         [0064]    (c) sequentially from first signal switch  822 , second signal switch  826  to last signal switch of second linear sensor array and synchronizing sequentially from first signal storage switch  872 - 1  to last signal storage switch  872 -n of first signal storage array  871 - 1  in second signal storage group  871  in such a manner that first signal switch  822  and first signal storage switch  872 - 1  are turned on at same time to store photo-signal of first photo-sensing element  821  into first signal storage device  871 - 1 - 1 , followed by turning on second signal switch  826  and second signal storage switch  872 - 2  to store photo-signal of second photo-sensing element  825  into second signal storage device  871 - 1 - 2  and so on to store photo-signal of last photo-sensing element of second linear sensor array into last signal storage device  871 - 1 -n. This concludes the storage of each photo-signal of second linear sensor array into respective each signal storage device of first signal storage array  871 - 1 . Reading and storing of first linear sensor array into second signal storage array  871 - 2  and reading and storing of second linear sensor array into first signal storage array  871 - 1  can be at different time or at same time, depending on individual design and application which is also for each case of the rest reading and storing operations.  
         [0065]    3. continuing on the reading and storing operation with the addition of one line image each time to read photo-signals of photo-sensing elements from first linear sensor array to one before last sensor array into one before last signal storage group  881  after first line image is one-to-one aligned to one before last linear sensor array and a line image with number of one before last is one-to-one aligned to first linear sensor array by turning on:  
         [0066]    (a) another one of first initial set-up switch  801 - 3 , other one of second initial set-up switch  802 - 2  and one of one before last initial set-up switch  803 - 1  and  
         [0067]    (b) sequentially from first signal switch  812 , second signal switch  816  to last signal switch of first linear sensor array and synchronizing sequentially from first signal storage switch  884 - 1  to last signal storage switch  884 -n of one before last signal storage array  881 -(m- 1 ) in such a manner that first signal switch  812  and first signal storage switch  884 - 1  are turned on at same time to store photo-signal of first photo-sensing element  811  into first signal storage device  881 -(m- 1 )- 1 , followed by turning on second signal switch  816  and second signal storage switch  884 - 2  to store photo-signal of second photo-sensing element  815  into second signal storage device  881 -(m- 1 )- 2  and so on to store photo-signal of last photo-sensing element of first linear sensor array into last signal storage device  881  (m- 1 )-n. This concludes the storage of each photo-signal of first linear sensor array into respective each signal storage device of one before last signal storage array  881 -(m- 1 ).  
         [0068]    (c) sequentially from first signal switch  822 , second signal switch  826  to last signal switch of second linear sensor array and synchronizing sequentially from first signal storage switch  883 - 1  to last signal storage switch  883 -n of two before last signal storage array  881 -(m- 2 ) in such a manner that first signal switch  822  and first signal storage switch  8831  are turned on at same time to store photo-signal of first photo-sensing element  821  into first signal storage device  881 -(m- 2 )- 1 , followed by turning on second signal switch  826  and second signal storage switch  883 - 2  to store photo-signal of second photo-sensing element  825  into second signal storage device  881 -(m- 2 )- 2  and so on to store photo-signal of last photo-sensing element of second linear sensor array into two before last signal storage device  881 -(m- 2 )-n. This concludes the storage of each photo-signal of second linear sensor array into respective each signal storage device of two before last signal storage array  881 -(m- 2 ) and operation of reading and storing continues on to one before last linear sensor array as described in (d) next below.  
         [0069]    (d) sequentially from first signal switch  832 , second signal switch  836  to last signal switch of one before last linear sensor array and synchronizing sequentially from first signal storage switch  882 - 1  to last signal storage switch  882 -n of first signal storage array  881 - 1  in such a manner that first signal switch  832  and first signal storage switch  882 - 1  are turned on at same time to store photo-signal of first photo-sensing element  831  into first signal storage device  881 - 1 - 1 , followed by turning on second signal switch  836  and second signal storage switch  882 - 2  to store photo-signal of second photo-sensing element  835  into second signal storage device  881 - 1 - 2  and so on to store photo-signal of last photo-sensing element of one before last linear sensor array into last signal storage device  881 - 1 -n. This concludes the storage of each photo-signal of one before last linear sensor array into respective each signal storage device of first signal storage array  881 - 1 . Therefore, each photo-signal of photo-sensor element in each linear sensor array from first to one before last linear sensor array is stored into respective signal storage device in one before last signal storage group  881 .  
         [0070]    4. reading photo-signals of photo-sensing elements from first linear sensor array to last sensor array into last signal storage group  891  after first line image is one-to-one aligned to last linear sensor array and a line image with a number of last is one-to-one aligned to first linear sensor array by turning on:  
         [0071]    (a) further another one of first initial set-up switch  801 - 4 , another one of second initial set-up switch  802 - 3  and other one of one before last initial set-up switch  803 - 2  and one of last initial set-up switch  804 - 1  and  
         [0072]    (b) sequentially from first signal switch  812 , second signal switch  816  to last signal switch of first linear sensor array and synchronizing sequentially from first signal storage switch  894 - 1  to last signal storage switch  894 -n of last signal storage array  891 -m in such a manner that first signal switch  812  and first signal storage switch  894 - 1  are turned on at same time to store photo-signal of first photo-sensing element  811  into first signal storage device  891 -m- 1 , followed by turning on second signal switch  816  and second signal storage switch  894 - 2  to store photo-signal of second photo-sensing element  815  into second signal storage device  891 -m- 2  and so on to store photo-signal of last photo-sensing element of first linear sensor array into last signal storage device  891 -m-n. This concludes the storage of each photo-signal of first linear sensor array into respective each signal storage device of last signal storage array  891 -m.  
         [0073]    (c) sequentially from first signal switch  822 , second signal switch  826  to last signal switch of second linear sensor array and synchronizing sequentially from first signal storage switch  893 - 1  to last signal storage switch  893 -n in such a manner that first signal switch  822  and first signal storage switch  893 - 1  are turned on at same time to store photo-signal of first photo-sensing element  821  into first signal storage device  891 -(m- 1 )-i, followed by turning on second signal switch  826  and second signal storage switch  893 - 2  to store photo-signal of second photo-sensing element  825  into second signal storage device  891 -(m- 1 )- 2  and so on to store photo-signal of last photo-sensing element of second linear sensor array into last signal storage device  891 -(m- 1 )-n. This concludes the storage of each photo-signal of second linear sensor array into respective each signal storage device of one before last signal storage array  891 -(m- 1 ). Operation of reading and storing continues on to one before last linear sensor array as described in (d) next below.  
         [0074]    (d) sequentially from first signal switch  832 , second signal switch  836  to last signal switch of one before last linear sensor array and synchronizing sequentially from first signal storage switch  892 - 1  to last signal storage switch  892 -n of second signal storage array  891 - 2  in such a manner that first signal switch  832  and first signal storage switch  882 - 1  are turned on at same time to store photo-signal of first photo-sensing element  831  into first signal storage device  891 - 2 - 1 , followed by turning on second signal switch  836  and second signal storage switch  892 - 2  to store photo-signal of second photo-sensing element  835  into second signal storage device  891 - 2 - 2  and so on to store photo-signal of last photo-sensing element of one before last linear sensor array into last signal storage device  891 - 2 -n. This concludes the storage of each photo-signal of one before last linear sensor array into respective each signal storage device of second signal storage array  891 - 2 .  
         [0075]    (e) sequentially from first signal switch  842 , second signal switch  846  to last signal switch of last linear sensor array and synchronizing sequentially from first signal storage switch  890 - 1  to last signal storage switch  890 -n of second signal storage array  891 - 2  in such a manner that first signal switch  842  and first signal storage switch  882 - 1  are turned on at same time to store photo-signal of first photo-sensing element  841  into first signal storage device  891 - 1 - 1 , followed by turning on second signal switch  846  and second signal storage switch  890 - 2  to store photo-signal of second photo-sensing element  845  into second signal storage device  891 - 1 - 2  and so on to store photo-signal of last photo-sensing element of last linear sensor array into last signal storage device  891 -I-n. This concludes the storage of each photo-signal of last linear sensor array into respective each signal storage device of first signal storage group  891 . Therefore, each photo-signal of photo-sensor element in each linear sensor array from first to last linear sensor array is stored into respective each signal storage device in last signal storage group  891 .Then, each linear sensor array is one-to-one aligned to next line image. Therefore, second line image is one-to-one aligned to last linear sensor array. Now it is ready to read out photo-signal due to each discrete image of first line image.  
         [0076]    Therefore, it can be seen that photo-signals stored in each first signal storage array from first signal storage group  861  to last signal storage group  891  are due to first line image, photo-signals stored in each second signal storage array from second storage group  871  to last signal storage group  891  are due to second line image, photo-signals stored in each third signal storage array from third storage group to last signal storage group  891  are due to third line image, and so on to photo-signals stored in one before last signal storage array  881 -(m- 1 ) in one before last signal storage group  881  and in last signal storage group  891 -(m- 1 ) are due to line image with a number of one before last and photo-signals stored in last signal storage array  891 -m in last signal storage group  891  are due to line image with a number of last. Consequently, second step is to read out photo-signals due to first line image and proceed process to detect second line image and so on to last line image. Second step comprises the steps of:  
         [0077]    A. reading out photo-signals due to first line image with steps of:  
         [0078]    1. reading out photo-signals in first signal storage array  861 - 1  in first signal storage group  861  by turning on:  
         [0079]    (a) first output switch  865 ,  
         [0080]    (b) sequentially signal storage switch from first signal storage switch  862 - 1  to last signal storage switch  862 -n,  
         [0081]    2. reading out photo-signals in first signal storage array  871 - 1  in second signal storage group  871  by turning on:  
         [0082]    (a) first output switch  875 ,  
         [0083]    (b) sequentially signal storage switch from first signal storage switch  872 - 1  to last signal storage switch  872 -n,  
         [0084]    3. continuing on reading out photo-signals in first signal storage array from third signal storage group to photo-signals in first signal storage array  881 - 1  in one before last signal storage group  881  by turning on:  
         [0085]    (a) first output switch  885 ,  
         [0086]    (b) sequentially signal storage switch from first signal storage switch  882 - 1  to last signal storage switch  882 -n,  
         [0087]    4. reading out photo-signals in first signal storage array  891 - 1  in last signal storage group  891  by turning on:  
         [0088]    (a) first output switch  895 ,  
         [0089]    (c) sequentially signal storage switch from first signal storage switch  890 - 1  to last signal storage switch  890 -n,  
         [0090]    5. obtaining total first photo-signal due to first discrete image of first line image which is equal to sum of read-out photo-signals of first signal storage devices from step (1) to step (4), total second photo-signal due to second discrete image of first line image which is equal to sum of read-out photo-signal of second signal storage device from step (1) to step (4) and total last photo-signal due to last discrete image of first line image which is equal to sum of read-out photo-signal of last signal storage device from step (1) to step (4).  
         [0091]    6. clearing all signal in signal storage devices in step (1) to (4).  
         [0092]    B. reading and storing photo-signals into signal storage devices which are cleared in step A-(6) to prepare for reading out photo-signals due to second line image with the steps of:  
         [0093]    1. reading photo-signals of first linear sensor array and storing into signal storage devices in last signal storage group  891  by turning on:  
         [0094]    (a) one of first signal reading switch  801 - 5  and  
         [0095]    (b) sequentially from first signal switch  812 , second signal switch  816  to last signal switch of first linear sensor array and synchronizing sequentially from first signal storage switch  890 - 1 , second signal storage switch  890 - 2  to last signal storage switch  890 -n of first signal storage array  891 - 1  in such a manner that first signal switch  812  and first signal storage switch  890 - 1  are turned on at same time to store photo-signal of first photo-sensing element  811  into first signal storage device  891   1 - 1 , followed by turning on second signal switch  816  and second signal storage switch  890 - 2  at same time to store photo-signal of second photo-sensing element  815  into second signal storage device  891 - 1 - 2  and so on to store photo-signal of last photo-sensing element into last signal storage device  891 - 1 -n to complete the photo-signal storage process to store photo-signals of first linear sensor array into first signal storage array  891 - 1 .  
         [0096]    2. reading photo-signals of second linear sensor array and storing into signal storage devices in one before last signal storage group  881  by turning on:  
         [0097]    (a) one of second signal reading switch  802 - 5  and  
         [0098]    (b) sequentially from first signal switch  822 , second signal switch  826  to last signal switch of second linear sensor array and synchronizing sequentially from first signal storage switch  882 - 1 , second signal storage switch  882 - 2  to last signal storage switch  882 -n of first signal storage array  881 - 1  in such a manner that first signal switch  822  and first signal storage switch  882 - 1  are turned on at same time to store photo-signal of first photo-sensing element  821  into first signal storage device  881 - 1 - 1 , followed by turning on second signal switch  826  and second signal storage switch  882 - 2  at same time to store photo-signal of second photo-sensing element  825  into second signal storage device  881 - 1 - 2  and so on to store photo-signal of last photo-sensing element into last signal storage device  881 - 1 -n to complete the storage process to store photo-signals of second linear sensor array into first signal storage array  881 - 1 .  
         [0099]    3. continuing on the operation of reading and storing photo-signals of the rest linear sensor arrays to the step of storing photo-signals of one before last linear sensor array into signal storage devices in second signal storage group  871  by turning on:  
         [0100]    (a) one of one before last signal reading switch  803 - 5  and  
         [0101]    (b) sequentially from first signal switch  832 , second signal switch  836  to last signal switch of one before last linear sensor array and synchronizing sequentially from first signal storage switch  872 - 1 , second signal storage switch  872 - 2  to last signal storage switch  872 -n of first signal storage array  871 - 1  in such a manner that first signal switch  832  and first signal storage switch  872 - 1  are turned on at same time to store photo-signal of first photo-sensing element  831  into first signal storage device  871 - 1 - 1 , followed by turning on second signal switch  836  and second signal storage switch  872 - 2  at same time to store photo-signal of second photo-sensing element  825  into second signal storage device  871 - 1 - 2  and so on to store photo-signal of last photo-sensing element into last signal storage device  871 - 1 -n to complete the storage process to store photo-signals of one before last linear sensor array into first signal storage array  871 - 1 .  
         [0102]    4. reading photo-signal of last linear sensor array and storing into signal storage devices in first signal storage group  861  by turning on:  
         [0103]    (a) one of last signal reading switch  804 - 5  and  
         [0104]    (b) sequentially from first signal switch  842 , second signal switch  846  to last signal switch of last linear sensor array and synchronizing sequentially from first signal storage switch  862 - 1 , second signal storage switch  862 - 2  to last signal storage switch  862 -n of first signal storage array  861 - 1  in such a manner that first signal switch  842  and first signal storage switch  862 - 1  are turned on at same time to store photo-signal of first photo-sensing element  841  into first signal storage device  871 - 1 - 1 , followed by turning on second signal switch  846  and second signal storage switch  862 - 2  at same time to store photo-signal of second photo-sensing element  845  into second signal storage device  861 - 1 - 2  and so on to store photo-signal of last photo-sensing element into last signal storage device  861 - 1 -n to complete the storage process to store photo-signals of last linear sensor array into first signal storage array  871 - 1 .  
         [0105]    C. repeating step A to read out photo-signals due to second line image with the same steps except that second output switches  876 ,  886 , and  896  are turned from second signal storage group  871  to last signal storage group  891  and step B to prepare for reading out photo-signals due to third line image,  
         [0106]    D. repeating step C for the rest line images by turning correspondent output switches. It can be seen that operation to turn on output switch is sequentially from first to last output switch and is rotated from first to last output switch again after the last output switch is turned on in each signal storage group in order to complete read out photo-signals due to all line images.  
         [0107]    Several other methods can also be applied to read out photo-signals in storage devices due to same line image. For example, one additional signal storage array is available in each signal storage group. Therefore, when reading out photo-signal due to first line image in signal storage groups, new photo-signals due to other line images can be simultaneously stored into the respective additional signal storage array in each signal storage group to speed up operation. Other method is for the case that each signal storage group has equal number of signal storage arrays, which is equal to one plus the number of signal storage arrays in last signal storage group  891 . This additional one signal storage array in last signal storage group  891  is then available to read and store other photo-signals while reading out photo-signals due to first line image. Of course, the number of signal storage arrays in each signal storage group is equal to the number of initial set-up switches or signal reading switches which are connected to each signal reading lines in that signal storage group. After completion of the first step to set up initial conditions as described above, the second step comprises the steps of:  
         [0108]    1. reading out stored photo-signals which are due to first line image by turning on  
         [0109]    (a) first output switch  865  of first signal storage group  861 , first output switch  875  of second signal storage group  871 , and so on to first output switch  885  of one before last signal storage group  881  and first output switch  895  of last signal storage group  891 ,  
         [0110]    (b) sequential from first signal storage switch to last signal storage switch of first signal storage array in each signal storage group,  
         [0111]    (c) obtaining total photo-signals due to first line image which is equal to sum of photo-signal which is read out from first signal storage array in each signal storage group.  
         [0112]    (d) clearing all photo-signals due to first line image in signal storage devices after completion of reading out operation.  
         [0113]    2. reading photo-signals of photo-sensing elements of each linear sensor array in multiple linear sensor array and stored into next available signal storage array in each signal storage group respectively at same time while reading out photo-signals due to first line image.  
         [0114]    3. repeating step 1 and 2 to read out photo-signals due to second line image and store photo-signals of photo-sensing elements of each linear sensor array in multiple linear sensor arrays into available respective signal storage array in each signal storage group,  
         [0115]    4. repeating step 3 for the rest line images.  
         [0116]    One advantage of FIG. 8 is that various different resolutions can be obtained for a given sensor array design with a modification of the wafer process. For example, when sensor array is designed for 1200 dpi resolution, then 600 dpi resolution can be obtained by connecting two neighboring signal switches together in wafer processing and adding outputs from two neighboring linear sensor arrays to result in an output for 600 dpi. For example, in FIG. 8, first signal switch  812  and second signal switch  816  are connected together, first signal switch  812  and second signal switch  816  are connected together, and so on. Similar connections are made on signal switches for the rest linear sensor arrays. Therefore, first and second photo-sensing elements  811  and  815  are turned on at same time to result in one photo-signal as photo-signal of first pixel for a resolution of 600 dpi application. The total photo-signal of first pixel for 600 dpi is sum of photo-signal of first pixel from first linear sensor array and photo-signal of first pixel from second linear sensor array. Similar process is followed to obtain total photo-signal of the rest pixels. With the same method, one can select neighboring 4 photo-sensing elements and 4 neighboring linear sensor arrays to obtain a resolution of 300 dpi. It can be seen that one can select a desired number to achieve a desired resolution. Another advantage is to obtain different photo-signals at same time by either coating a desired color pattern on multiple on multiple linear sensor arrays or by the incident of color light pattern an line images which are one-to-one aligned to respective line sensor arrays. Those who are skillful in the field can easily modify to satisfy a desired application.  
         [0117]    The preferred embodiments of this invention have been described in detail. The scope and the spirits of this invention are not limited by the preferred embodiments described above. It is set by the claims listed below.