Imaging device capable of carrying out automatic focusing with stable detection accuracy and at a high response speed

Claim 2

An automatic focusing imaging device comprising: an imaging element for forming an image of an image pick-up light from an object through a lens system to apply photoelectric conversion to said image pick-up light at a photoelectric conversion surface provided on said imaging element to provide video signal, said imaging element and said lens system defining the elements of an optical pair a camera circuit for processing said video signal subjected to photoelectric conversion by said imaging element to generate a luminance signal, said camera circuit utilizing one of a plurality of processing techniques signal including filtering and blanking; filter means for extracting, as an analog signal, a high frequency band component of said video signal, said filter means comprising a high-pass filter for extracting an edge signal corresponding to said high frequency band component; a detector for detecting said edge signal extracted by said high-pass filter to output a detected signal; a logarithmic converter for applying logarithmic conversion to said detected signal from said detector to provide a focal point voltage having a predetermined characteristic; an analog/digital converter for converting said focal point voltage to data in the form of a digital signal; calculation means for calculating in advance an in-focus position of at least one element from said optical pair which includes said lens system and said imaging element where said high frequency band component takes a maximum level to generate a control signal, said calculation means comprising a microcomputer responsive to said in-focus position to generate said control signal; a lens drive mechanism responsive to said control signal to move said at least one element from said optical pair which includes said imaging element; and non-linear conversion means being provided at the preceding stage of said analog-digital converter, and for correcting in advance deterioration of the quantization resolution of said high frequency band component quantized at the time of calculation of the in-focus position of said at least one element from said optical pair; and wherein said microcomputer includes means for dividing a screen captured by said imaging element into a plurality of blocks to extract for each of said blocks a high frequency band component to determine high frequency component information corresponding to each of said blocks to calculate an in-focus value for each of said blocks to determine an in-focus value for the entire screen by using calculated results for each block to generate said control signal for carrying out focusing using said lens drive mechanism.

Claim 3

An automatic focusing imaging device as set forth in claim 1, wherein said imaging device comprises second filter means for extracting, as a second analog signal, a low frequency component from said video signal outputted from said imaging element, and means for inputting a high frequency component analog signal extracted by said filter means and a second analog signal with respect to a low frequency component extracted by said second filter means to carry out calculation thereof, thus to provide high frequency component information from which a flicker component is eliminated.

Claim 4

An automatic focusing imaging device as set forth in claim 2, wherein said imaging device comprises a second detector for detecting low frequency component extracted by said second filter means, a second logarithmic converter for applying logarithmic conversion to output from said second detector, a switch for carrying out switching between a focal point voltage signal and a luminance low frequency signal outputted from said respective logarithmic converters in response to a switching control signal outputted from said calculation means, said A/D converter converting either one of analog signals switched by said switch to a digital signal, said calculation means responsive to output data as said digital signal outputted from said A/D converter to output said switching control signal to said switch, and to output a lens drive signal as said control signal.

Claim 5

An automatic focusing imaging device as set forth in claim 3, wherein said imaging device further comprises detection means for detecting focal depth information of said lens system to output it, said calculation means being operative to respond to said detected focal depth information to calculate an in-focus value indicating the state where said lens system is in focus.

Claim 6

An automatic focusing imaging device as set forth in claim 4, wherein said detection means is comprised of an iris encoder and a zoom encoder provided in said lens system, and for detecting said focal depth information to deliver it to said calculation means.

Claim 7

An automatic focusing imaging device as set forth in claim 1, wherein said imaging device comprises detection means for detecting said focal depth information of said lens system to output it, and said calculation means responsive to said focal depth information detected by said detection means to calculate an in-focus value showing the state where said lens system is in focus.

Claim 8

The automatic focusing imaging device according to claim 1, wherein said imaging device further comprises a zoom encoder and an iris encoder for detecting a focal length and an entrance pupil of said lens system to deliver said focal length and said entrance pupil to said microcomputer in order to give focal depth information of an object to said microcomputer.

Claim 9

The automatic focusing imaging device according to claim 1, wherein said microcomputer determines an in-focus point by using a predetermined calculation formula on the basis of a first focal point voltage in a predetermined specific field, a second focal point voltage in a field after the position of a focusing lens of said lens system is moved by a predetermined distance, and a third focal point voltage in a field after the position of said focusing lens is further moved by said predetermined distance to thereby provide focal depth information of said lens system.

Claim 10

An automatic focusing imaging device comprising: an imaging element for forming an image of an image pick-up light from an object through a lens system to apply photoelectric conversion to said image pick-up light at a photoelectric conversion surface provided on said imaging element to provide a video signal, said imaging element and said lens system defining the elements of an optical pair; a camera circuit for processing said video signal subjected to photoelectric conversion by said imaging element to generate a luminance signal, said camera circuit utilizing one of a plurality of processing techniques including filtering and blanking; filter means for extracting, as an analog signal, a high frequency band component of said video signal, said filter means comprising a high-pass filter for extracting an edge signal corresponding to said high frequency band component; a detector for detecting said edge signal extracted by said high-pass filter to output a detected signal; a logarithmic converter for applying logarithmic conversion to said detected signal from said detector to provide a focal point voltage having a predetermined characteristic; an analog/digital converter for converting said focal point voltage to data in the form of a digital signal; calculation means for calculating in advance an in-focus position for at least one of the elements from said optical pair which includes said lens system and said imaging element where said high frequency band component takes a maximum level to generate a control signal, said calculation means being responsive to said in-focus position to generate said control signal, said calculation means comprising a microcomputer having means for dividing a screen captured by said imaging element into a plurality of blocks to extract for each of said blocks a high frequency band component to determine high frequency component information corresponding to each of said blocks to calculate an in-focus value for each of said blocks to determine an in-focus value for the entire screen by using calculated results for each block to generate said control signal for carrying out focusing; a lens drive mechanism responsive to said control signal for carrying out focusing by moving said at least one element of said optical pair; non-linear conversion means provided at the preceding stage of said analog/digital converter, and for correcting in advance deterioration of the quantization resolution of said high frequency band component quantized at the time of calculation of the in-focus position of said at least one element from said optical pair; detection means for detecting focal depth information from said lens system to output said information; and wherein said microcomputer is responsive to said focal depth information detected by said detection means to calculate said in-focus value indicative of the state where said lens system is in focus.

Claim 11

An automatic focusing imaging device comprising: an imaging element for forming an image of an image pick-up light from an object through a lens system to apply photoelectric conversion to said image pick-up light at a photoelectric conversion surface provided on said imaging element to provide a video signal, said imaging element and said lens system defining the elements of an optical pair; a camera circuit for processing said video signal subjected to photoelectric conversion by said imaging element to generate a luminance signal, said camera circuit utilizing one of a plurality of processing techniques including filtering and blanking; filter means for extracting, as an analog signal, a high frequency band component of said video signal, said filter means comprising a high-pass filter for extracting an edge signal corresponding to said high frequency band component; a detector for detecting said edge signal extracted by said high-pass filter to output a detected signal; a logarithmic converter for applying logarithmic conversion to said detected signal from said detector to provide a focal point voltage having a predetermined characteristic; an analog/digital converter for converting said focal point voltage to data in the form of a digital signal; calculation means for calculating in advance an in-focus position for at least one of the elements from said optical pair which includes said lens system and said imaging element where said high frequency band component takes a maximum level to generate a control signal, said calculation means being responsive to said in-focus position to generate said control signal, said calculation means comprising a microcomputer having means for dividing a screen captured by said imaging element into a plurality of blocks to extract for each of said blocks a high frequency band component to determine high frequency component information corresponding to each of said blocks to calculate an in-focus value for each of said blocks to determine an in-focus value for the entire screen by using calculated results for each block to generate said control signal for carrying out focusing; a lens drive mechanism responsive to said control signal for carrying out focusing by moving said at least one element of said optical pair; non-linear conversion means provided at the preceding stage of said analog/digital converter, and for correcting in advance deterioration of the quantization resolution of said high frequency band component quantized at the time of calculation of the in-focus position of said at least one element from said optical pair; detection means for detecting focal depth information from said lens system to output said information; and wherein said microcomputer is responsive to said focal depth information detected by said detection means to calculate said in-focus value indicative of the state where said lens system is in focus.