Abstract:
A multi-plate solid-state imaging element module comprising a plurality of solid-state imaging devices identical in structure, each comprising a set of pixels, wherein said plurality of solid-state imaging devices are arranged so that the sets of pixels of said plurality of solid-state imaging devices are effectively deviated to each other, so as to effectively arrange all the pixels of the plurality of solid-state imaging devices in a checkered form.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a multi-plate solid-state imaging element module and apparatus having, say, four solid-state imaging devices arranged deviated at pixels, and more particularly to a multi-plate solid-state imaging element module and apparatus realized a high resolution.  
         [0003]     2. Description of the Related Art  
         [0004]     Four-plate type solid-state imaging apparatus are described, say, in JP-A-7-250332 and JP-A-60-154781 noted in the below. In the four-plate type, resolution can be improved by arranging the solid-state imaging devices with deviation at pixels. This fact is explained with reference to  FIGS. 6 and 7 .  
         [0005]      FIGS. 6A, 6B ,  6 C and  6 D respectively show solid-state imaging devices  1 ,  2 ,  3 ,  4  that are identical in structure. The solid-state imaging devices  1 ,  2 ,  3 ,  4  are each arranged with pixels (each represented by a “circle” put therein with a solid-state imaging device number to which the relevant pixel belongs, in the figure), wherein pixel pitch and size (opening) are equal between the solid-state imaging devices  1 ,  2 ,  3 ,  4 .  
         [0006]     Relatively to the arrangement position of the solid-state imaging device  1 , the solid-state imaging device  2  is arranged deviated a half pixel pitch in both x (horizontal) and y (vertical) directions, the solid-state imaging device  3  is arranged deviated a half pixel pitch in the y direction, and the solid-state imaging device  4  is arranged deviated a half pixel pitch in the x direction. Due to this, the solid-state imaging devices  1 ,  2 ,  3 ,  4  have pixels arranged in positions shown in  FIG. 7 . Namely, it can be understood that the four-plate solid-state imaging apparatus is effectively given a resolution four times greater.  
         [0007]      FIG. 8  is a pixel arrangement diagram where the solid-state imaging devices  1  and  2  are arranged with deviation at pixels so that the real pixels thereof are effectively arranged in a checkered form. Where the pixels are in a checkered arrangement (honeycomb arrangement), the data at an imaginary pixel, shown at a dotted-lined circle; is determined by an interpolation with the image data of the surrounding real pixels  1 ,  2 , thereby making the image data in a tetragonal lattice form.  
         [0008]     Namely, the two-plate solid state imaging apparatus having  FIG. 8  devices  1 ,  2  provides an image having a resolution equal to the resolution of an image obtained by the  FIG. 7  four-plate solid-state imaging apparatus. Even in case the solid-state imaging devices to mount are increased to four from two in the number, the resolution is not improved.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a multi-plate solid-state imaging device, module and apparatus.  
         [0010]     A multi-plate solid-state imaging element module according to the present invention is a multi-plate solid-state imaging element module including a plurality of solid-state imaging devices identical in structure and arranged deviated at pixels thereby increasing an effective number of pixels, multi-plate solid-state imaging element module characterized in that: the plurality of solid-state imaging devices, after arranged deviated at pixels, are effectively arranged in a checkered form at all the pixels thereof.  
         [0011]     In other words, the multi-plate solid-state imaging element module according to the present invention comprises a plurality of solid-state imaging devices identical in structure, each comprising a set of pixels, wherein said plurality of solid-state imaging devices are arranged so that the sets of pixels of said plurality of solid-state imaging devices are effectively deviated to each other, so as to effectively arrange all the pixels of the plurality of solid-state imaging devices in a checkered form.  
         [0012]     In the multi-plate solid-state imaging element module in the invention, the set of pixels of each of the solid-state imaging devices may be arranged in a checkered form.  
         [0013]     In the multi-plate solid-state imaging element module in the invention, the solid-state imaging devices may be four solid-state imaging devices.  
         [0014]     An imaging apparatus according to the invention comprises: the above-mentioned multi-plate solid-state imaging element module; and an operation section that interpolates for data of an imaginary pixel in a position to fill between the pixels effectively arranged, from pixel data of the pixels effectively arranged around the relevant imaginary pixel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a functional block diagram of a four-plate solid-state imaging apparatus according to an embodiment of the present invention;  
         [0016]      FIG. 2  is a structural view of a four-plate solid-state imaging element module  22  shown in  FIG. 1 ;  
         [0017]      FIG. 3  is a graph showing a spectral characteristic of a color separation prism and trimming color filter for use on the four-plate solid-state imaging element module shown in  FIG. 2 ;  
         [0018]      FIG. 4  is a typical surface figure of a solid-state imaging device constituting the four-plate solid-state imaging element module shown in  FIG. 2 ;  
         [0019]      FIG. 5  is an arrangement figure of the real pixels on the four-plate solid-state imaging element module shown in  FIG. 2 ;  
         [0020]      FIGS. 6A  to  6 D are typical surface figures of a solid-state imaging device for use on the related-art four-plate solid-state imaging apparatus;  
         [0021]      FIG. 7  is an arrangement figure of the real pixels where four solid-state imaging devices in a tetragonal lattice arrangement of pixels are arranged deviated at pixels thereby placing all the pixels in a tetragonal lattice arrangement; and  
         [0022]      FIG. 8  is an arrangement figure of the real pixels where two solid-state imaging devices in a tetragonal lattice arrangement of pixels are arranged deviated at pixels thereby placing the pixels in a checkered arrangement. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     With reference to the drawings, an embodiment of the present invention will now be explained.  
         [0024]      FIG. 1  is a block configuration diagram of a digital camera according to one embodiment of the present invention. The digital camera includes an optical system  21  mounting thereon a lens and restriction for focusing the light of from a subject, a four-plate solid-state imaging element module  22  according to the embodiment, and an infrared absorbing filter  23  arranged between the optical system  21  and the module  22 .  
         [0025]     The digital camera, in the embodiment, has also a CDS circuit  24  that fetches red (R), blue (B), first green (G 1 ) and second green (G 2 ) signals and performs a correlated-double sampling thereon, a pre-processing circuit  25  that fetches an output signal from the CDS circuit  24  and performs a gain-control processing thereon, an A/D conversion circuit  26  that converts the R, G 1 , G 2  and B analog signals outputted from the pre-processing circuit  25  into digital signals, a circuit  27  that fetches the R, G 1 , G 2  and B image signals outputted from the A/D conversion circuit  26  and performs a signal processing such as white-balance correction and gamma correction thereon and makes a signal compression/decompression processing of an photographic image, an image memory  28  connected to the circuit  27 , and a record/display circuit  29  that records the photographic image data the circuit  27  processed in a not-shown external memory and displays it on a liquid-crystal display provided on a camera backside or the like.  
         [0026]     The digital camera further has a system control circuit  30  that takes total control of the digital camera overall, a synchronization signal circuit  31  that generates a synchronization signal according to an instruction signal of from the system control circuit  30 , and an imaging-device drive circuit  32  that outputs a drive signal to the solid-state imaging devices of the four-plate solid-state imaging element module  22  depending upon a synchronization signal.  
         [0027]     In the digital camera of this embodiment, the optical system  21  is placed under control in its lens focusing and restriction depending upon an instruction signal of from the system control circuit  30 . Through the optical system  21  and infrared absorbing filter  23 , a subject optical image is focused on the four solid-state imaging devices of the module  22 . In accordance with the optical image due to light reception, the solid-state imaging devices output red (R), first green (G 1 ), second green (G 2 ) and blue (B) signals. The pre-process circuit  25  takes gain control or so of the R, G 1 , G 2  and B signals, according to the synchronization signal. The circuit  27  performs a signal processing, etc. depending upon the instruction from the system control circuit  30 . Due to this, the photographic image is reproduced based upon the R, G 1 , G 2  and B signals outputted from the solid-state imaging element module  22 . The image data compressed in a JPEG form is recorded in the external memory.  
         [0028]      FIG. 2  is a structural view of the four-plate solid-state imaging element module  22 . The module  22  has color separation prism that separates incident light into four parts, and four solid-state imaging devices  22 R,  22 G 1 ,  22 G 2 ,  22 B.  FIG. 3  is a graph exemplifying a spectral characteristic of the blue (B), first green (G 1 ), second green (G 2 ) and red(R) portions of light which the color separation prism divided the incident light into four parts.  
         [0029]     As shown in  FIG. 2 , the color separation prism has a first prism member  40 , a second prism member  41 , a third prism member  42 , a fourth prism member  43 , a blue(B)-light reflecting dichroic film  45  provided between the members  40  and  41 , a red(R)-light reflecting dichroic film  46  provided between the members  41  and  42 , and a second-green(G 2 )-light reflecting dichroic film  47  provided between the members  42  and  43 .  
         [0030]     The color separation prism also has a blue(B)-light trimming color filter  40 a applied on a light-output surface of the first prism member  40 , a red(R)-light trimming color filter  41   a  applied on a light-output surface of the second prism member  41 , a second-green (G 2 )-light trimming color filter  42   a  applied on a light-output surface of the third prism member  42 , and a first-green (G)-light trimming color filter  43   a  applied on a light-output surface of the fourth prism member  43 .  
         [0031]     The trimming color filter  40   a,    41   a,    42   a,    43   a  serves for trimming in a manner such that the output light from the prism  40 ,  41 ,  42 ,  43  has a bell-shaped spectral characteristic, as shown in  FIG. 3 .  
         [0032]     The solid-state imaging device  22 B is arranged opposed at its light-receiving surface to the trimming color filter  40   a.  The solid-state imaging device  22 R is arranged opposed at its light-receiving surface to the trimming color filter  41 a. The solid-state imaging device  22 G 1  is arranged opposed at its light-receiving surface to the trimming color filter  42   a.  The solid-state imaging device  22 G 2  is arranged opposed at its light-receiving surface to the trimming color filter  43   a.    
         [0033]     In the case the light from a subject is incident upon the four-plate solid-state imaging element module  22  structured as above, the blue portion of the incident light reflects upon the dichroic film  45  and within the first prism  40 , to enter the solid-state imaging device  22 B. The red portion of the incident light reflects upon the dichroic film  46  and within the second prism  41 , to enter the solid-state imaging device  22 R. The G 2  portion of the light reflects upon the dichroic film  47  and within the third prism  42 , to enter the solid-state imaging device  22 G 2  while the G 1  portion of the light travels straight in the fourth prism—member  43  and enters the solid-state imaging device  22 G 1 , Design is made to provide an equal optical path length to between the light-incident surface of the first prism member  40  and the light-receiving surfaces of the solid-state imaging devices  22 B,  22 R,  22 G 1 ,  22 G 2 .  
         [0034]      FIG. 4  is a typical surface view of the solid-state imaging device  22 R (solid-state imaging devices  22 B,  22 G 1 ,  22 G 2  structured similarly). The solid-state imaging device  22 R has a multiplicity of photo-diodes  52  in a surface of a semiconductor substrate  51 . The photo-diodes  52  are formed in a two-dimensional array arrangement, wherein the photo-diodes  52  on the odd row are formed deviated a half pitch relative to the photo-diodes  52  on the even row, i.e. honeycomb pixel arrangement (checkered arrangement).  
         [0035]     Between the horizontally-adjacent ones of the photodiodes  52 , vertical transfer lines (VCCDs)  53  are formed extending zigzag in the vertical direction. In the lower side region of the semiconductor substrate  51 , a horizontal transfer line (HCCD)  54  is provided connected to the ends of the respective vertical transfer lines  53 .  
         [0036]     The signal charge, built up on the photo-diode  52  commensurate with the light received, is read out onto the adjacent vertical transfer line  53  and then transferred to the horizontal transfer line  54 . Thee signal charge, transferred to the horizontal transfer line  54 , is transferred along the horizontal transfer line  54  up to an output end thereof. An output amplifier  55  is provided at the output end of the horizontal transfer line, to output as image data a voltage signal dependent upon a signal charge amount.  
         [0037]     Incidentally, although the terms “vertical” and “horizontal” are used, those simply mean respectively “one direction” and “direction nearly vertical to the one direction”. Although the solid-state imaging devices  22 R,  22 B,  22 G 1 ,  22 G 2  in the embodiment are of the CCD type, those may be MOS solid-state imaging devices where the pixels are in a checkered arrangement.  
         [0038]     The four-plate solid-state imaging element module  22  in the embodiment uses four solid-state imaging devices  22 R,  22 B,  22 G 1 ,  22 G 2  that are same in structure, thus being arranged with deviation at pixels. Namely, relatively to the arrangement position of the solid-state imaging device  22 R for detecting a red portion of light, the blue-light detecting solid-state imaging device  22 B is arranged deviated a half pixel pitch in an x-direction (horizontally) or in a y-direction (vertically).  
         [0039]     The G 1 -light detecting solid-state imaging device  22 G 1  is arranged deviated a half oblique pixel pitch in a 45-degree oblique right direction, relatively to the solid-state imaging device  22 R. The G 2 -light detecting solid-state imaging device  22 G 2  is arranged deviated a half oblique pixel pitching a 45 degree oblique left direction relatively to the solid-state imaging device  22 R.  
         [0040]     By thus arranging the four solid-state imaging devices, the solid-state imaging devices are effectively arranged as shown in  FIG. 5 . According to  FIG. 5 , provided that the pixels of the solid-state imaging devices  22 R,  22 B,  22 G 1 ,  22 G 2  (shown by circles in which described detecting portions of light R, B, G 1 , G 2  respectively illustrating belonging to the solid-state imaging devices) are real pixels, the real pixels are effectively arranged in a checkered form.  
         [0041]     When a subject is taken an image of by the digital camera that mounts a four-plate solid-state imaging element module  22  having such a structure, R, B, G 1  and G 2  signals are outputted from the real pixels of the four-plate solid-state imaging element module  22  to the  FIG. 1  CDS circuit  24 . The signals are outputted as digital image data from the A/D conversion circuit  26  to the signal processing circuit  27 .  
         [0042]     In the signal processing circuit  27 , various image processes are performed including gamma correction, white balance correction and RGB/YC conversion. On this occasion, interpolation operating process is also done.  
         [0043]     The image data, outputted from the real pixels of the four-plate solid-state imaging element module  22 , provides a checkered form when arranged, as shown in  FIG. 5 . Where pixel data is merely in a checkered arrangement, there arises a need to place the image data in a tetragonal lattice arrangement because of the impossibility of of configuring an “image” that the pixel data is in a tetragonal lattice arrangement. Namely, image data is needed for an imaginary pixel  60  between the real pixels in the checkered arrangement.  
         [0044]     For this reason, the signal processing circuit  27  produces data for the imaginary pixel  60  by an interpolation with the image data of the real pixels lying around the relevant imaginary pixel  60 , and arranging it as data for the imaginary pixels  60 .  
         [0045]     Namely, in the embodiment, the four solid-state imaging devices are arranged deviated at pixels and the real pixels, after device arrangement, are placed in a checkered form. Accordingly, the number of real pixels is four times the number of the real pixels of one solid-state imaging device while the number of imaginary pixels  60  is obtainable in the same number, thus providing eight times the total number of pixels and hence eight times the resolution.  
         [0046]     In this manner, for a multi-plate solid-state imaging apparatus, it is preferable to determine the pixel deviational position in a manner all the pixels are effectively arranged in a checkered form (honeycomb arrangement) after pixel deviational arrangement, in order to improve the resolution through increasing the number of effective number of pixels. Where using a solid-state imaging device in a honeycomb pixel arrangement, at least four solid-state imaging devices are needed.  
         [0047]     Incidentally, the embodiment explained on the four-plate solid-state imaging apparatus for taking a color image, it is possible to structure a four-plate solid-state imaging apparatus for taking a black-and-white image instead of a color image. In such a case, it is satisfactory to use a beam splitter capable of splitting incident light into four portions, in place of the color separation prism and trimming color filter.  
         [0048]     Meanwhile, the embodiment used the color separation prism and the trimming color filter. Alternatively, it is possible to use a solid-state imaging device using a beam splitter, for splitting incident light into four portions, in place of the color separation prism and trimming color filter and laying color filters on a pixel-by-pixel basis.  
         [0049]     The embodiment was four-plate type. Alternatively, by using honeycomb-pixel-arranged solid-state imaging devices in the number of  4  to the power of n (e.g. sixteen), an imaging apparatus having a resolution higher than the number of solid-state imaging devices, similarly to the foregoing embodiment.  
         [0050]     Meanwhile, the embodiment used four colors of R, G 1 , G 2  and B. Alternatively, three colors of R, G and B may be used so that the G portion of light exiting the  FIG. 2  prism member  41  can be divided by a beam splitter into two parts having the same spectral characteristic and allowed to enter two solid-state imaging devices separately.  
         [0051]     According to the invention, because the pixels after a deviational arrangement of solid-state imaging devices are in a checkered arrangement, the data of an imaginary pixel position can be interpolated with the image data of the surrounding pixels thus improving the resolution.  
         [0052]     The four-plate solid-state imaging apparatus according to the invention is allowed to obtain a resolution higher than the number of solid-state imaging devices, and hence useful if applied to a digital camera.  
         [0053]     The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.