CROSS REFERENCES TO RELATED APPLICATIONS 
   The present invention contains subject matter related to Japanese Patent Application JP 2006-100931 filed in the Japanese Patent Office on Mar. 31, 2006, the entire contents of which being incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an imaging device, a camera system and a driving method of the same, provided with a solid state imaging device such as a CCD (Charge Coupled Device), and a CMOS (Complementary Metal Oxide Semiconductor) sensor, particularly to an imaging device and a camera system in which in a two dimensional pixel array using a plurality of color filters, the pixel arrangement and the pixel array are sequentially scanned for exposure and read operation. 
   2. Description of the Related Art 
   For a color filter arrangement of an imaging device, the Bayer array is known which uses two green (G) filters, a single red (R) filter, and a single blue (B) filter of three primary colors with excellent color reproducibility. The Bayer array is an arrangement that places more importance on the resolution of brightness than color. 
   An imaging device is proposed in which a pixel arrangement is provided with transparent filters arranged in order to increase sensitivity while excellent color reproducibility is retained in the color filter arrangement (for example, see JP-A-8-23542 (Patent Reference 1)). 
   In addition, an imaging device is proposed in which the transparent filter arrangement is improved to secure the signal charge amount and the color resolution even though pixels are miniaturized (for example, see JP-A-2004-304706 (Patent Reference 2)). 
   SUMMARY OF THE INVENTION 
   However, in the imaging device described above, the apparatus has limitations on the improvement of resolution and color reproducibility. 
   In addition, it is difficult to control color information at dark places and bright places using color filter pixels and transparent filter pixels freely, and it is difficult to create almost natural color depending on luminosity. 
   Thus, it is desirable to provide an imaging device and a camera system with excellent color reproducibility which can improve resolution. 
   It is also desirable to provide an imaging device and a camera system which can create almost natural color depending on luminosity. 
   An imaging device according to an embodiment of the invention is an imaging device including: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which converts light transmitted through the pixel is converted into an electric signal, wherein in the pixel array part, among a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an oblique pixel array system, and a clear pixel having a high transmittance is arranged in an oblique pixel array system at a given position of a given row and a given column in the oblique pixel array with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel. 
   The oblique pixel array means that the pixels of the columns of each series are offset by a predetermined amount from the pixels of the columns of the other series. 
   Preferably, in the pixel array part, a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter are arranged in an array, and the clear pixel is uniformly arranged between the color filter pixels. 
   Preferably, the pixel array part includes a pixel row and a pixel column formed only of the clear pixel. 
   In addition, another pixel array part includes a pixel row and a pixel column formed only of the clear pixel. 
   Preferably, the pixel array part includes a pixel row and/or a pixel column having the clear pixel and at least one color filter pixel mixed. 
   Preferably, a read channel exclusive for the clear pixel and a read channel exclusive for the color filter pixel are provided separately. 
   Preferably, a function is provided that separately performs electronic shutter drive for the clear pixel and for the color filter pixel. 
   An imaging device according to an embodiment of the invention is an imaging device including: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which converts light transmitted through the pixel into an electric signal, wherein in the pixel array part, among a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an array, a clear pixel having a high transmittance is arranged at a given position of a given row and a given column in the array pixel arrangement with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel, and a read channel exclusive for the clear pixel and a read channel exclusive for the color filter pixel are separately provided. 
   An imaging device according to an embodiment of the invention is an imaging device including: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which converts light transmitted through the pixel into an electric signal, wherein in the pixel array part, among a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an array, a clear pixel having a high transmittance is arranged at a given position of a given row and a given column in the array pixel arrangement with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel, and a function is provided that separately performs electronic shutter drive for the clear pixel and for the color filter pixel. 
   A camera system according to an embodiment of the invention is a camera system including: an imaging device; an optical system operable to lead incident light to an imaging part of the imaging device; and a signal processing circuit operable to process an output signal of the imaging device, wherein the imaging device includes: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which converts light transmitted through the pixel into an electric signal, wherein in the pixel array part, among a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an oblique pixel array system, a clear pixel having a high transmittance is arranged in an oblique pixel array system at a given position of a given row and a given column in the oblique pixel array with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel, a read channel exclusive for the clear pixel and a read channel exclusive for the color filter pixel are separately provided, and a function is provided that separately performs electronic shutter drive for the clear pixel and for the color filter pixel. 
   A camera system according to an embodiment of the invention is a camera system including: an imaging device; an optical system operable to lead incident light to an imaging part of the imaging device; and a signal processing circuit operable to process an output signal of the imaging device, wherein the imaging device includes: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which the light transmitted through the pixel is converted into an electric signal, wherein in the pixel array part, among a first color filter pixel having a peak of spectral sensitivity characteristics in red, a second color filter pixel having a peak in blue, and a third color filter pixel having a peak in green, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an array, a clear pixel having a high transmittance is arranged at a given position of a given row and a given column in the array pixel arrangement with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel, a read channel exclusive for the clear pixel and a read channel exclusive for the color filter pixel are separately provided, and a function is provided that separately performs electronic shutter drive for the clear pixel and for the color filter pixel. 
   According to an embodiment of the invention, an imaging device can be implemented which intends an improved resolution with excellent color reproducibility. 
   In addition, according to an embodiment of the invention, almost natural color can be created depending on luminosity. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a block diagram depicting an exemplary configuration of the essential part of an imaging device according to an embodiment of the invention; 
       FIG. 2  shows a circuit diagram depicting an exemplary unit pixel according to the embodiment; 
       FIG. 3  shows a diagram schematically depicting an exemplary pixel arrangement of a pixel array part  11  according to the embodiment; 
       FIG. 4  shows a diagram conceptually depicting the spectral characteristics of color filter pixels R, G, and B and a clear pixel C; 
       FIG. 5  shows a diagram illustrative of an oblique pixel array; 
       FIG. 6  shows a diagram illustrative of advantages to adopt the oblique pixel array; 
       FIG. 7  shows a diagram depicting a basic oblique pixel array unit in which a clear pixel C is inserted in the middle of four color filter pixels R, G, G, and B in the Bayer array; 
       FIG. 8  shows a diagram illustrative of the read mode for the pixel array part when driven in the embodiment; 
       FIG. 9  shows a diagram schematically depicting the drive mode for an electronic shutter in the embodiment; 
       FIG. 10  shows a diagram illustrative of a read scheme of the clear pixel C in a read channel CH-A, in which nine pixels are added and read; 
       FIG. 11  shows a diagram illustrative of the read scheme of the color filter pixels (color pixels) R, G, and B in the read channel CH-B, in which nine pixels are added and read; 
       FIG. 12  shows a diagram illustrative of the read scheme of the clear pixel C in the read channel CH-A, in which five pixels are added and read; 
       FIG. 13  shows a diagram illustrative of the read scheme of the color filter pixels (color pixels) R, G, and B in the read channel CH-B, in which five pixels are added and read; 
       FIG. 14  shows a block diagram depicting an exemplary configuration of a signal processing part in the subsequent stage according to the embodiment; 
       FIG. 15  shows a diagram illustrative of a white balance control process at bright places in the embodiment; 
       FIG. 16  shows a diagram illustrative of the white balance control process at dark places in the embodiment; 
       FIG. 17  shows a diagram simply depicting a partial cross section of the pixel array part according to the embodiment; 
       FIG. 18  shows a diagram simply depicting a partial cross section of another exemplary configuration of the pixel array part according to the embodiment; 
       FIG. 19  shows a diagram depicting a second exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 20  shows a diagram depicting an exemplary configuration of in which the clear pixels and color filter pixels are mixed in the same row in the oblique pixel array; 
       FIG. 21  shows a diagram depicting a third exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 22  shows a diagram depicting a fourth exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 23  shows a diagram depicting a fifth exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 24  shows a diagram depicting a sixth exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 25  shows a diagram depicting a seventh exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 26  shows a diagram depicting an eight exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 27  shows a diagram depicting a ninth exemplary pixel arrangement of the pixel array part according to the embodiment; 
       FIG. 28  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 4  is rotated into the rectangular array; 
       FIG. 29  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 19  is rotated into the rectangular array; 
       FIG. 30  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 21  is rotated into the rectangular array; 
       FIG. 31  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 22  is rotated into the rectangular array; 
       FIG. 32  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 23  is rotated into the rectangular array; 
       FIG. 33  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 24  is rotated into the rectangular array; 
       FIG. 34  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 25  is rotated into the rectangular array; 
       FIG. 35  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 26  is rotated into the rectangular array; 
       FIG. 36  shows a diagram depicting an example in which the oblique pixel array shown in  FIG. 27  is rotated into the rectangular array; 
       FIG. 37  shows a diagram depicting an exemplary configuration in which the clear pixels and color filter pixels are mixed in the same row in the rectangular array; 
       FIG. 38  shows a diagram depicting an exemplary configuration in which a shutter wiring is provided to each of color filter pixels and clear pixels in the rectangular array; and 
       FIG. 39  shows a block diagram depicting the outline of the configuration of a camera system according to an embodiment of the invention. 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, an embodiment of the invention will be described with reference to the drawings. 
     FIG. 1  shows a block diagram depicting an exemplary configuration of the essential part of an imaging device according to an embodiment of the invention. 
   As shown in  FIG. 1 , an imaging device  10  has a pixel array part (ARY)  11 , a clear pixel horizontal scanning circuit (CHSCAN)  12 , a color pixel horizontal scanning circuit (CLRHSCAN)  13 , a vertical scanning circuits (VSCAN)  14 - 1  and  14 - 2 , a timing control part  15 , a power source part  16 , a clear pixel analog front end part (CAFE)  17 , and a color pixel analog front end part (CLRAFE)  18 . 
   For example, in the pixel array part  11 , sensor unit pixels are arranged in an array in a predetermined arrangement form. 
   In addition, the pixel array part  11  is wired with a transfer selection line, a reset line, and a select line in each row in the pixel arrangement, and a signal line in each column in the pixel arrangement. 
     FIG. 2  shows a circuit diagram depicting an exemplary unit pixel according to the embodiment. In  FIG. 2 , a CMOS sensor is shown as an example. 
   A unit pixel  110  shown in  FIG. 2  has a photodiode  111 , a transfer transistor  112 , an amplifier transistor  113 , a select transistor  114 , a reset transistor  115 , and a floating node ND  111 . 
   The photodiode  111  photoelectrically converts incident light into signal charge in the amount of electric charge in accordance with the light quantity (for example, electrons). 
   The transfer transistor  112  is connected between the cathode of the photodiode  111  and the floating node ND  111 , and the gate is connected to a transfer selection line TRFL, which has a function that it is conducted (turned on) to transfer the signal charge stored in the photodiode  111  to the floating node ND  111 . 
   The amplifier transistor  113  and the select transistor  114  are serially connected between a power source potential VDD and a signal line SGNL. 
   The gate of the amplifier transistor  113  is connected to the floating node ND  111 , which amplifies the potential of the floating node ND  111 , and outputs it to the signal line SGNL through the select transistor  114 . 
   The gate of the select transistor  114  is connected to a select line SELL. 
   In the reset transistor  115 , the source is connected to the floating node ND  111 , the drain is connected to a predetermined potential line, and the gate is connected to a reset line RSTL, which has a function that resets the potential of the floating node ND  111 . 
   The transfer selection line TRFL, the select line SELL, and the reset line RSTL which are wired to each row in the pixel arrangement are selectively driven by the vertical scanning circuit  14 . The signal line SGNL selectively transfers signals read out of pixels to the clear pixel horizontal scanning circuit  12 , and the color pixel horizontal scanning circuit  13 . 
   The drive timing of the horizontal scanning circuits  12  and  13  and the vertical scanning circuit  14  is controlled by the timing control part  15 . 
     FIG. 3  shows a diagram schematically depicting an exemplary pixel arrangement of the pixel array part  11  according to the embodiment. 
   As shown in  FIG. 3 , the pixel array part  11  shown in  FIG. 3  adopts an oblique pixel array, and is formed in a pixel arrangement in which the clear pixel C that has a high transmittance is inserted between a color filter pixel R having the peak of the spectral sensitivity characteristics in red, the color filter pixel G having the peak in green, and the color filter pixel B having the peak in blue, each including a color filter in the vertical and oblique directions uniformly, whereby the deviation of the resolution is removed. 
   In addition, the clear pixel C is not necessarily white. 
   In the pixel arrangement shown in  FIG. 3 , even numbered rows and even numbered columns including the zeroth row and the zeroth column are all configured of color filter pixels, and add numbered rows and add numbered columns are all configured of clear pixels C. 
     FIG. 4  shows a diagram conceptually depicting the spectral characteristics of the color filter pixels R, G, and B and the clear pixel C. 
   In  FIG. 4 , the horizontal axis depicts the wavelength, and the vertical axis depicts the relative output. 
   As apparent from  FIG. 4 , the clear pixel C has sensitivity nearly throughout the visible light area (wavelengths of 360 nm to 700 nm). In other words, since the clear pixel C has a wide wavelength area component (including all the color signals), it is easy to provide color reproduction at the border of the clear pixel. 
   Hereinafter, the characteristic configuration of the pixel array part  11  will be described more in detail with reference to  FIGS. 5 to 13 . 
   As shown in  FIG. 5 , in the pixel array part  11  according to the embodiment, a so-called rectangular unit pixel RGPX L is arranged in a so-called oblique pixel OBLPXL in which the unit pixel is rotated at a predetermined angle θ (θ=0° to 90°) about a column axis CAX. 
   An advantage that adopts the oblique pixel OBLPXL array will be described with reference to  FIG. 6 . In addition, in  FIG. 6 , the Bayer array is taken as an example. 
   The pixel pitch of the oblique pixel OBLPXL is 1/√2 when the turning angle θ is 45 degrees where the pixel pitch PTC of the rectangular pixel RGPXL is 1. Thus, the pixel pitch can be made smaller without changing the size of the pixel. 
   In the embodiment, as shown in  FIG. 7 , the clear pixel C is inserted in the middle of four color filter pixels R, G, G, and B in the Bayer array in the oblique pixel array to form the basic oblique pixel array unit. 
   The Bayer array is left to easily perform a color interpolation process for a signal processing system. 
   For the read mode of the pixel array part  11  having the configuration when it is driven, the clear pixel C and the color filter pixels (color pixels) R, G, and B are read by different channels. 
   In the embodiment, for example, as shown in  FIG. 8 , a read channel CH-A exclusive for clear pixels and a read channel CH-B exclusive for color filter pixels are provided separately to read the clear pixel C and the color filter pixels R, G, and B independently. 
   In the example shown in  FIG. 8 , the clear pixel horizontal scanning circuit  12  is arranged as a read processing system for the channel CH-A on the upper side in the drawing, and the color filter pixel (color pixel) horizontal scanning circuit  13  is arranged as a read system for the channel CH-B in the lower side in the drawing. 
   In the embodiment, a signal line SGNL-O wired to the add numbered column is connected to the clear pixel horizontal scanning circuit  12 , and a signal line SGNL-E wired to the even numbered column is connected to the color filter pixel (color pixel) horizontal scanning circuit  13 . 
   In the embodiment, in addition to adopting the mode in which the clear pixel C and the color filter pixels (color pixels) R, G, and B are read by different channels, it is configured in which the time period, rate, and gain in processing in the subsequent stage of the electronic shutter (rolling shutter) are separately changed between the clear pixel C and the color filter pixels (color pixels) R, G, and B. 
     FIG. 9  shows a diagram schematically depicting the drive mode of the electronic shutter in the embodiment. 
   In the embodiment, as shown in  FIG. 9 , the pixels can be read by varying the time for the rolling shutter between the storage time for the clear pixel and the color pixel. 
   In addition, the shutter speed may be varied separately between the clear pixel and the color filter pixels (color pixels) R, G, and B. 
   For example, at a bright place, the shutter for the clear pixel is released quickly to prevent the saturation of the clear pixel, whereas at a dark place, in reverse, the shutter for the clear pixel is released slowly to increase sensitivity. 
   With this configuration, color information is increased at a bright place, and color information is decreased at a dark place, whereby natural color can be created. 
   In the embodiment, in order to implement high speed read, a so-called adding read scheme is adopted. 
     FIG. 10  shows a diagram illustrative of the read scheme of the clear pixel C in the read channel CH-A, in which nine pixels are added and read. 
     FIG. 11  shows a diagram illustrative of the read scheme of the color filter pixels (color pixels) R, G, and B in the read channel CH-B, in which nine pixels are added and read. 
   As shown in  FIGS. 10 and 11 , nine pixels are added, whereby the interpolation process can be easily performed without losing the arrangement in which the clear pixel C is arranged in the middle of the Bayer array. 
     FIG. 12  shows a diagram illustrative of the read scheme of the clear pixel C in the read channel CH-A, in which five pixels are added and read. 
     FIG. 13  shows a diagram illustrative of the read scheme of the color filter pixels (color pixels) R, G, and B in the read channel CH-B, in which five pixels are added and read. 
   As shown in  FIGS. 12 and 13 , also in the case of adding five pixels, the pixels at closer positions are added in the case of adding nine pixels, whereby color reproducibility is improved without losing the arrangement in which the clear pixel C is arranged in the middle of the Bayer array. 
   From the view point of the read rate, adding nine pixels is advantageous. 
   As described above, the read signal of the clear pixel C read in accordance with the adding read scheme is forwarded to the clear pixel AFE  17  through the horizontal scanning circuit  12 . 
   In addition, the read signal of the color filter pixels (color pixels) R, G, and B is forwarded to the clear pixel AFE  18  through the horizontal scanning circuit  13 . 
   In the AFEs  17  and  18 , the read signal is processed into analog form such as amplification, and converted to a digital signal, and then forwarded to a signal processing part in the subsequent stage. 
     FIG. 14  shows a block diagram depicting an exemplary configuration of a subsequent signal processing part according to the embodiment. 
   As shown in  FIG. 14 , a signal processing part  20  has a white balance adjusting part  21 , a color pixel interpolating part  22 , a brightness adjusting part  23 , and a clear pixel interpolating part  24 . 
   The white balance adjusting part  21  adjusts white balance based on the signals of the clear pixel C and the color filter pixels (color pixels) R, G, and B forwarded from the AFEs  17  and  18 . 
     FIG. 15  shows a diagram illustrative of the white balance control process at bright places in the embodiment. 
     FIG. 16  shows a diagram illustrative of the white balance control process at dark places in the embodiment. 
   At bright places, the white balance adjusting part  21  adjusts the signals of the clear pixel C and the other color filter pixels (color pixels) R and B on the basis of the signal of the color filter pixel (color pixel) G. 
   On the other hand, at dark places, the white balance adjusting part  21  adjusts the signals of the color filter pixels (color pixels) R, G, and B on the basis of the signal of the clear pixel C. 
   The interpolating part  22  performs the interpolation process only for the color filter pixel (color pixel) part after white balance is adjusted. 
   The brightness adjusting part  23  adjusts the brightness signals of the color filter pixels (color pixels) R, G, and B and the brightness signal of the clear pixel C to output a brightness signal Y. 
   The interpolating part  24  performs the interpolation process for the white pixel based on the brightness signal to output a color signal SC. 
   As described above, the configuration and function of each part of the imaging device  10  according to the embodiment have been described. 
   Next, the structure of the pixel array part will be described. 
     FIG. 17  shows a diagram simply depicting a partial cross section of the pixel array part according to the embodiment. 
   In  FIG. 17 ,  30  denotes a semiconductor substrate,  31  denotes a device separation area, and  41  to  43  denote a microlens. 
   On the semiconductor substrate  30 , N-sensor areas  32  and  33  of the color filter pixel (color pixel) and an N-sensor area  34  of the clear pixel are formed between the device separation areas  31 . 
   In addition,  35  to  37  denote a P+ layer, and  38  denotes a P− layer. 
   In the embodiment, N− ions are implanted deep only in the N-sensor area  34  of the clear pixel into the N-sensor areas  32  and  33  of the color filter pixel (color pixel) to increase the sensitivity on the high wavelength side. For example, it is configured to sense the wavelength area of near infrared rays. 
     FIG. 18  shows a diagram simply depicting a partial cross section of another exemplary configuration of the pixel array part according to the embodiment. 
   The pixel array part shown in  FIG. 18  is configured in which the position of the microlens  41  of the clear pixel C is varied from the height position of the other color filter pixels (color pixels) for adjustment. 
   Accordingly, the beam condensing rate can be increased. 
   As described above, according to the embodiment, the pixel array part  11  adopts the oblique pixel array, and is formed in a pixel arrangement in which the clear pixel C that has a high transmittance is uniformly inserted in the vertical and oblique directions between a color filter pixel R having the peak of the spectral sensitivity characteristics in red, the color filter pixel G having the peak in green, and the color filter pixel B having the peak in blue, each including a color filter, whereby the deviation of the resolution is removed. It is configured in which the read channel CH-A exclusive for clear pixels and the read channel CH-B exclusive for color filter pixels are provided separately, and the clear pixel C and the color filter pixels R, G, and B are read separately. In addition to adopting the scheme to read the clear pixel C and the color filter pixels (color pixels) R, G, and B by the different channels, and the time period, rate, and gain in processing in the subsequent stage of the electronic shutter (rolling shutter) are changed separately for the clear pixel C and the color filter pixels (color pixels) R, G, and B. Therefore, the following advantage can be obtained. 
   For example, the pixel is rotated at an angle of 45 degrees to make the pixel pitch to 1/√2, and to increase the resolution. The area can be doubled as compared with the case in which a typical pixel array has the same pitch, sensitivity can be increased, and a clear (transparent) pixel is inserted into the color coating of the oblique pixel array to further improve the sensitivity. 
   In addition, when the clear pixel is arranged in the middle of the Bayer array, the color interpolation process is facilitated. 
   In addition, the shutter time and gain can be changed separately between the clear pixel C and the color filter pixels (color pixels) R, B and G. Therefore, the output of the clear pixel is made moderate at a bright place, whereas the output is increased at a dark place, whereby a more natural picture can be created as though a real one is seen by eyes. 
   As described above, the improved sensitivity is intended to enhance the signal-to-noise ratio, and high speed read with low intensity can be implemented due to the improved sensitivity. 
   In high speed read, for example, nine pixels are added to provide the same arrangement after addition, whereby an advantage is exerted that signal processing in color production is facilitated. 
   In addition, in the discussion above, an example has been described in which the pixel array part  11  adopts the oblique pixel array as shown in  FIG. 3 , and is formed in the pixel arrangement in which the clear pixel C having a high transmittance is inserted between the color filter pixel R having the peak of the spectral sensitivity characteristics in red, the color filter pixel G having the peak in green, and the color filter pixel B having the peak in blue each including a color filter in the vertical and oblique directions, whereby the deviation of the resolution is eliminated. 
   However, an embodiment of the invention is not limited to the pixel arrangement shown in  FIG. 3 , which can adopt various forms as a pixel arrangement into which the clear pixel is inserted, and can obtain the same advantages as described above. 
   Hereinafter, another exemplary configuration of the pixel arrangement will be described. 
     FIG. 19  shows a diagram depicting a second exemplary pixel arrangement of the pixel array part according to the embodiment. 
   In the pixel arrangement of a pixel array part  11 A shown in  FIG. 19 , a clear pixel C is arranged at the position at which the color filter (color pixel) G in the pixel arrangement shown in  FIG. 3 , and a color filter (color pixel) G is arranged at the position at which the clear pixel C shown in  FIG. 3  is arranged. 
   In the pixel arrangement shown in  FIG. 19 , in the even numbered rows including the zeroth row, the color filter pixel B and the clear pixel C are arranged alternately in a single pixel, in the even numbered columns including the zeroth column, the color filter pixel R and the clear pixel C are arranged alternately in a single pixel, and the add numbered row and the add numbered column are formed only of the color filter pixel G. 
   Also in the case of adopting the pixel array, the read channel CH-A exclusive for clear pixels and the read channel CH-B exclusive for color filter pixels are provided separately, and the clear pixel C and the color filter pixel R, G, B are read separately. In addition to adopting the scheme to read the clear pixel C and the color filter pixels (color pixels) R, G, and B by the different channels, it is configured in which the time period, rate, and gain in processing at the subsequent stage of the electronic shutter (rolling shutter) are changed separately for the clear pixel C and the color filter pixels (color pixels) R, G, and B. 
   However, the clear pixel C and the color filter pixel R or B are mixed in the same row, which causes the necessity of arranging a wiring for the color filter pixel (color pixel) and a wiring for the clear pixel C. 
     FIG. 20  shows a diagram depicting an exemplary configuration in which the clear pixel and the color filter pixel are mixed in the same row. 
   In this case, as shown in  FIG. 20 , a shutter wiring and a clear pixel wiring for the color filter pixel (color pixel) are wired in a single row. More specifically, a color pixel reset wiring RSTL 1  and a clear pixel reset wiring RSTL 2  are wired. 
   The configuration of the unit pixel is the same as that in  FIG. 2 , omitting the detailed description. 
     FIG. 21  shows a diagram depicting a third exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 B shown in  FIG. 21  is an arrangement in which the clear pixel is included in all the rows and columns. 
   In the pixel arrangement, the clear pixel is arranged at intervals, but also in this case, the configuration similar to that in  FIG. 20  is adopted, whereby the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 22  shows a diagram depicting a fourth exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 C shown in  FIG. 22  is an arrangement in which the clear pixel is included in each row and each column except the zeroth row and the zeroth column. 
   Also in the pixel arrangement, the clear pixel is arranged at intervals, but also in this case, the configuration similar to that in  FIG. 20  is adopted, whereby the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 23  shows a diagram depicting a fifth exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 D shown in  FIG. 23  is an arrangement in which the position of arranging the color filter (color pixel) G in the add numbered row of the pixel arrangement shown in  FIG. 3  is replaced by the color filter (color pixel) R. 
   In the pixel arrangement shown in  FIG. 23 , as similar to the array shown in  FIG. 3 , the add numbered row and the add numbered column are configured of only the clear pixel C. 
   In the pixel arrangement shown in  FIG. 23 , the pixel column of only the color filter (color pixel) G, the pixel column of the clear pixel C, the pixel column of the color filters (color pixels) R and B mixed are in turn arranged from the zeroth column, and the combination is repeated. 
   Also in the pixel arrangement, the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 24  shows a diagram depicting a sixth exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 E shown in  FIG. 24  is an arrangement in which the clear pixel C is arranged at the position of arranging the color filter (color pixel) G at the third, seventh, eleventh and fifteenth rows in the add numbered rows of the pixel arrangement shown in  FIG. 3  to increase the clear pixel, intending that the sensitivity is more improved. 
   Also in the pixel arrangement, the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 25  shows a diagram depicting a seventh exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 F shown in  FIG. 25  is an arrangement in which the color filter pixel (color pixel) G is removed, and in the even numbered rows and the even numbered columns including the zeroth row and the zeroth column, the pixel rows and the pixel columns are formed to have the color filter pixels (color pixels) R and B alternately arranged. 
   In this case, information about the color signal is formed based on information about the clear pixel and/or information about the color filters (color pixels) R and B having the spectral characteristics shown in  FIG. 4 . 
   Also in the pixel arrangement, the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 26  shows a diagram depicting an eighth exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 G shown in  FIG. 26  is an arrangement in which the color filter pixel (color pixel) G is further removed from the pixel arrangement shown in  FIG. 25 , the pixel row including the clear pixel C is increased, and the pixel column including the clear pixel C is formed in every column. 
   In this case, information about the color signal is formed based on information about the clear pixel and/or information about the color filters (color pixels) R and B having the spectral characteristics shown in  FIG. 4 . 
   Also in the pixel arrangement, the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
     FIG. 27  shows a diagram depicting a ninth exemplary pixel arrangement of the pixel array part according to the embodiment. 
   The pixel arrangement of a pixel array part  11 H shown in  FIG. 27  is an arrangement in which the color filter pixel (color pixel) G is further removed from the pixel arrangement shown in  FIG. 25 , the pixel row including the clear pixel C is increased, and the pixel column including the clear pixel C is formed in every column. In this case, the pixel row including the color filter pixel (color pixel) is formed to have the pixel row including only the color filter pixel (color pixel) B and the clear pixel C and the pixel row including only the color filter pixel (color pixel) R and the clear pixel C. 
   In this case, information about the color signal is formed based on information about the clear pixel and/or information about the color filters (color pixels) R and B having the spectral characteristics shown in  FIG. 4 . 
   Also in the pixel arrangement, the shutter can be released separately from the portions of the color pixel, and the clear pixel can be read separately. 
   As described above, exemplary configurations of the oblique pixel array has been described. In the pixel arrangement, the characteristic configuration, in which the shutter can be released separately from the portions of the color pixel and the clear pixel can be read separately, can be adapted not only to the oblique pixel array but also to the pixel arrangements of the rectangular array as shown in  FIGS. 28 to 36 , for example, and the same advantages can be obtained as those in the oblique array. 
     FIG. 28  shows an example in which the oblique pixel array shown in  FIG. 4  is turned to the rectangular array,  FIG. 29  shows an example in which the oblique pixel array shown in  FIG. 19  is turned to the rectangular array,  FIG. 30  shows an example in which the oblique pixel array shown in  FIG. 21  is turned to the rectangular array,  FIG. 31  shows an example in which the oblique pixel array shown in  FIG. 22  is turned to the rectangular array,  FIG. 32  shows an example in which the oblique pixel array shown in  FIG. 23  is turned to the rectangular array,  FIG. 33  shows an example in which the oblique pixel array shown in  FIG. 24  is turned to the rectangular array,  FIG. 34  shows an example in which the oblique pixel array shown in  FIG. 25  is turned to the rectangular array,  FIG. 35  shows an example in which the oblique pixel array shown in  FIG. 26  is turned to the rectangular array, and  FIG. 36  shows an example in which the oblique pixel array shown in  FIG. 27  is turned to the rectangular array. 
   In addition, the rectangular array, as shown in  FIG. 37 , as similar to  FIG. 20 , the shutter wiring and the clear pixel wiring for the color filter pixel (color pixel) are wired to a single row, more specifically, a color pixel reset wiring RSTL 1  and a clear pixel reset wiring RSTL 2  are wired. 
   The configuration of the unit pixel is the same as that in  FIG. 2 , omitting the detailed description. 
   Furthermore, as shown in  FIG. 38 , in the rectangular array (or the oblique array), it may be configured in which the shutter wiring is provided for every color filter pixel and every clear pixel. 
   In this case, a color pixel reset wirings RSTL 1  and RSTL 3  and a clear pixel reset wiring RSTL 2  are wired. 
   The configuration of the unit pixel is the same as that in  FIG. 2 , omitting the detailed description. 
     FIG. 39  shows a block diagram depicting the outline of the configuration of a camera system according to an embodiment of the invention. 
   A camera system  50  is configured to have an imaging device  51 , an optical system which leads incident light into the pixel area of the imaging device  51 , for example, a lens  52  which forms incident light (image) onto the imaging area, a drive circuit  53  which drives the imaging device  51 , and a signal processing circuit  54  which processes the output signal of the imaging device  51 . 
   In the camera system  50 , as the imaging device  51 , the imaging device according to the embodiment is sued. 
   The drive circuit  53  is a circuit also corresponding to the timing control part shown in  FIG. 1 , which drives the imaging device  51 . 
   The signal processing circuit  54  applies various signal processes to the output signal Vout of the imaging device  51 , and outputs it as a video signal. 
   As described above, according to the camera system, the imaging device according to the embodiment is used as the imaging device  51 , whereby high speed operation can be secured. Therefore, a high quality image with less noise can be obtained in a small circuit scale at low power consumption. 
   In addition, the imaging device according to an embodiment of the invention may be a single chip imaging device, or may be a module imaging device which is formed as an assembly of a plurality of chips. When it is an imaging device formed as an assembly of a plurality of chips, chips are fabricated separately such as a sensor chip, and a signal processing chip for digital signal processing, and it may be further include an optical system. 
   It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
An imaging device includes: a pixel array part in which a plurality of pixels with different characteristics of spectral sensitivity are arranged in an array and which converts light transmitted through the pixel into an electric signal, wherein in the pixel array part, among a first color filter pixel, a second color filter pixel, and a third color filter pixel, each including a color filter, at least a plurality of the first color filter pixels and the second color filter pixels is arranged in an oblique pixel array system, and a clear pixel having a high transmittance is arranged in an oblique pixel array system at a given position of a given row and a given column in the oblique pixel array with respect to the first color filter pixel, the second color filter pixel, and the third color filter pixel.