Solid-state image pickup apparatus with horizontal thinning and a signal reading method for the same

Abstract

In a solid-state image pickup apparatus, a solid-state image sensor includes a color filter having filter segments arranged in a pattern, photosensitive cells for photoelectrically transducing light transmitted through the filter segments to generate corresponding signal charges, vertical transfer devices for vertically transferring the signal charges, a horizontal transfer device for transferring the signal charges input from the vertical transfer devices in the horizontal direction, and a charge holding circuit intervening between the vertical and horizontal transfer devices for temporarily storing the signal charges. A signal charge thinning circuit omits signal charges whose color pattern, which is generated by mixing signal charges having the same color attribute in the direction of row in the filter pattern to thereby horizontally thin the signal charges, is different in positional relation from the filter pattern.

1 . A solid-state image pickup apparatus comprising:
 a solid-state image sensor; and   a drive signal generator;   said solid-state image sensor comprising:   a color filter having a plurality of color filter segments arranged in a pattern for separating light incident from a scene into respective colors;   a plurality of photosensitive cells associated one-to-one with said plurality of color filter segments each for photoelectrically transducing the light transmitted through an associated color filter segment to thereby generate a corresponding signal charge;   a plurality of gates each being configured to be selectively closed for storing the signal charge having a color attribute corresponding to particular one of the plurality of color filter segments in associated one of said plurality of photosensitive cells or opened for reading out said signal charge;   a plurality of first transfer devices adjoining said plurality of gates for vertically transferring the signal charges via said plurality of gates;   a second transfer device transferring the signal charges in a horizontal direction perpendicular to said plurality of first transfer devices;   a charge holding circuit intervening between bottom stages of said plurality of first transfer devices and said second transfer device for temporarily storing the signal charges fed from said bottom stages; and   a signal charge thinning circuit omitting signal charges whose color pattern, which is generated by mixing the signal charges having the same color attribute in a direction of row in the pattern of said color filter to thereby thin said signal charges in the horizontal direction, is different in positional relation from said pattern of said color filter;   said drive signal generator generating drive signals for selectively opening or closing said gates, drive signals for said plurality of first transfer devices and said second transfer device, read signals for reading out the signal charges held in said charge holding circuit, and thinning drive signals for said signal charge thinning circuit.   
   
   
       2 . The apparatus in accordance with  claim 1 , wherein said signal charge thinning circuit has an electrode structure in which electrodes of the gates different in positional relation from electrodes of the gates present in the pattern of said color filter are wired independently of the other electrodes. 
   
   
       3 . The apparatus in accordance with  claim 2 , wherein said drive signal generator is inhibited, in accordance with horizontal thinning, from generating the drive signals that open the gates different in position from the other gates present in the pattern of said color filter. 
   
   
       4 . The apparatus in accordance with  claim 1 , wherein said charge signal thinning circuit comprises a horizontal charge sweeping circuit extending along said second transfer device for sweeping out the signal charges whose color pattern, which is generated by mixing the signal charges of the same color attribute in the direction of row in the pattern of said color filer, is different in positional relation from the pattern of said color filter. 
   
   
       5 . The apparatus in accordance with  claim 4 , wherein said drive signal generator generates a drive signal for causing, in accordance with horizontal thinning, the signal charges whose color pattern is different in positional relation from the pattern of said color filter to be swept out to said horizontal charge sweeping circuit. 
   
   
       6 . The apparatus in accordance with  claim 3 , wherein said solid-state image sensor further comprises:
 a first amplifier amplifying the signal charges each being generated by mixture of the same color;   a second amplifier directly amplifying the signal charges read out from said photosensitive cells; and   a switching circuit selectively connecting said first amplifier or said second amplifier to a source in accordance with whether or not the signal charges fed are subjected to mixture, and switching an output from said first amplifier or said second amplifier connected to said source;   said first amplifier, said second amplifier and said switching circuit being positioned at an output side of said second transfer device.   
   
   
       7 . The apparatus in accordance with  claim 5 , wherein said solid-state image sensor further comprises:
 a first amplifier amplifying the signal charges each being generated by mixture of the same color;   a second amplifier directly amplifying the signal charges read out from said photosensitive cells; and   a switching circuit selectively connecting said first amplifier or said second amplifier to a source in accordance with whether or not the signal charges fed are subjected to mixture, and switching an output from said first amplifier or said second amplifier connected to said source;   said first amplifier, said second amplifier and said switching circuit being positioned at an output side of said second transfer device.   
   
   
       8 . The apparatus in accordance with  claim 6 , further comprising an amplification adjusting circuit adjusting a level of amplification in accordance with whether or not an analog signal output from said solid-state image sensor is subjected to mixture of the same color. 
   
   
       9 . The apparatus in accordance with  claim 7 , further comprising an amplification adjusting circuit adjusting a level of amplification in accordance with whether or not an analog signal output from said solid-state image sensor is subjected to mixture of the same color. 
   
   
       10 . The apparatus in accordance with  claim 8 , further comprising a signal processor digitizing the analog signal output from said solid-state image sensor and execute bit shift with, among resulting digital data, digital data simply read out from said photosensitive cells in a direction in which digital data increase in level. 
   
   
       11 . The apparatus in accordance with  claim 9 , further comprising a signal processor digitizing the analog signal output from said solid-state image sensor and execute bit shift with, among resulting digital data, digital data simply read out from said photosensitive cells in a direction in which digital data increase in level. 
   
   
       12 . The apparatus in accordance with  claim 10 , wherein said color filter includes a color pattern in which colors facing each other at one of a pair of diagonal corners are identical with each other while colors facing each other at the other pair of diagonal corners are different from each other and from said color positioned at the one pair of diagonal corners,
 said charge thinning circuit omitting, in said color pattern having a plurality of columns as a unit, the signal charges on particular one of said plurality of columns.   
   
   
       13 . The apparatus in accordance with  claim 11 , wherein said color filter includes a color pattern in which colors facing each other at one of a pair of diagonal corners are identical with each other while colors facing each other at the other pair of diagonal corners are different from each other and from said color positioned at the one pair of diagonal corners,
 said charge thinning circuit omitting, in said color pattern having a plurality of columns as a unit, the signal charges on particular one of said plurality of columns.   
   
   
       14 . The apparatus in accordance with  claim 12 , wherein the particular column included in the unit contains, among three colors arranged in accordance with horizontal mixture of two pixels of the same color, either one of two colors other than a color larger in number than said two colors. 
   
   
       15 . The apparatus in accordance with  claim 13 , wherein the particular column included in the unit contains, among three colors arranged in accordance with horizontal mixture of two pixels of the same color, either one of two colors other than a color larger in number than said two colors. 
   
   
       16 . The apparatus in accordance with  claim 1 , wherein said drive signal generator generates particular drive signals in each of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       17 . The apparatus in accordance with  claim 3 , wherein said drive signal generator generates particular drive signals in each of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       18 . The apparatus in accordance with  claim 5 , wherein said drive signal generator generates particular drive signals in each of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       19 . The apparatus in accordance with  claim 14 , wherein said drive signal generator generates particular drive signals in each of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       20 . The apparatus in accordance with  claim 15 , wherein said drive signal generator generates particular drive signals in each of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       21 . The apparatus in accordance with  claim 16 , wherein said drive signal generator selects said second movie mode when the magnification is above unity. 
   
   
       22 . The apparatus in accordance with  claim 17 , wherein said drive signal generator selects said second movie mode when the magnification is above unity. 
   
   
       23 . The apparatus in accordance with  claim 18 , wherein said drive signal generator selects said second movie mode when the magnification is above unity. 
   
   
       24 . The apparatus in accordance with  claim 19 , wherein said drive signal generator selects said second movie mode when the magnification is above unity. 
   
   
       25 . The apparatus in accordance with  claim 20 , wherein said drive signal generator selects said second movie mode when the magnification is above unity. 
   
   
       26 . A signal reading method comprising:
 a first step of separating light incident from a scene being picked up into color components with color filter segments to thereby generate corresponding signal charges each having a particular color attribute;   a second step of executing, when the signal charges of a same color are mixed in a horizontal direction as pixels, horizontal-mixture reading including thinning that omits the signal charges whose color pattern resulting from said horizontal-mixture reading is different in position from the pattern in which the color filter segments are arranged; and   a third step of adjusting levels of the signal charges produced by the thinning in accordance with a number of pixels used to generate the signal charges by the horizontal mixture and indicative of the pattern of the color filter segments.   
   
   
       27 . The method in accordance with  claim 26 , wherein the thinning comprises either one of inhibiting the signal charges different in position from the pattern of the color filter segments from being read out and deleting said signal charges. 
   
   
       28 . The method in accordance with  claim 26 , wherein when two signal charges are mixed in the horizontal direction, said third step executes level adjustment by digitizing said two signal charges and then effecting bit shift only with image data equal in level to a single signal charge. 
   
   
       29 . The method in accordance with  claim 27 , wherein when two signal charges are mixed in the horizontal direction, said third step executes level adjustment by digitizing said two signal charges and then effecting bit shift only with image data equal in level to a single signal charge. 
   
   
       30 . The method in accordance with  claim 26 , wherein said third step comprises selecting either one of first levels of the signal charges read out for the horizontal mixture and second levels of the other signal charges subjected to said horizontal mixture and multiplying said first levels by a preselected constant. 
   
   
       31 . The method in accordance with  claim 29 , wherein said third step comprises selecting either one of first levels of the signal charges read out for the horizontal mixture and second levels of the other signal charges subjected to said horizontal mixture and multiplying said first levels by a preselected constant. 
   
   
       32 . The method in accordance with  claim 26 , wherein when the color pattern includes a color pattern in which colors facing each other at one of a pair of diagonal corners are identical with each other while colors facing each other at the other pair of diagonal corners are different from each other and from said color positioned at the one pair of diagonal corners, said second step omits, in said color pattern having a plurality of columns as a unit, the signal charges on particular one of said plurality of columns. 
   
   
       33 . The method in accordance with  claim 31 , wherein when the color pattern includes a color pattern in which colors facing each other at one of a pair of diagonal corners are identical with each other while colors facing each other at the other pair of diagonal corners are different from each other and from said color positioned at the one pair of diagonal corners, said second step omits, in said color pattern having a plurality of columns as a unit, the signal charges on particular one of said plurality of columns. 
   
   
       34 . The method in accordance with  claim 26 , wherein the signal charges are read out in accordance with either one of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie, and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       35 . The method in accordance with  claim 33 , wherein the signal charges are read out in accordance with either one of a first movie mode for displaying image data generated by executing horizontal thinning mixture with the signal charges, which are read out from said solid-state image sensor, as a movie, and a second movie mode for displaying said image data by omitting, in accordance with a magnification of said image data, the signal charges causative of a positional shift of the color pattern as a movie. 
   
   
       36 . The method in accordance with  claim 34 , wherein said second movie mode is selected when the magnification is above unity. 
   
   
       37 . The method in accordance with  claim 35 , wherein said second movie mode is selected when the magnification is above unity.