Focus detecting method and apparatus

Claim 1

An automatic focusing device for a camera comprising: first and second sensor groups; means for projecting images of an object transmitted through a focusing lens onto said first and second sensor groups; means for shifting at least one of said images on said sensor groups; means for converting outputs of said first and second sensor groups to digital numbers; means for storing said digital numbers; calculating means for determining in succession: (1) a first set of successive values of: ##EQU10## for successive values of p for positive values of F, and a second set of successive values of: ##EQU11## for successive values of p for negative values of F where i k are ones of said digital numbers corresponding to sensors of said first sensor group, j k are ones of said digital numbers corresponding to sensors of said second sensor group with k indicating sensor positions within said sensor groups, n is the number of sensors in each said sensor group, p=-1, 0, 1, 2, . . . P with P being an integer less than n, β 0 =A 0 /(n-1), β p+2 =A 0 /(n-p-1) and A 0 is a predetermined constant; (2) values of F=F S and F=F S+1 where F S represents the value of F before a change in the sign of F and F S+1 represents the value of F after a change in the sign of F for successive values of p, and S corresponds to an image movement amount from a prior position to a position corresponding to the value of p before said change in sign of F; and (3) a value of M=S+F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said first set of values and M=S-F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said second set of values; and means for moving said lens directly from said prior position to a focused position determined in accordance with said value of M.

Claim 5

A method for automatically focusing a camera having a focusing lens, first and second sensor groups, and means for projecting images of an object transmitted through said focusing lens onto said first and second sensor groups, said method comprising; shifting at least one of said images on said sensor groups; converting outputs of said first and second sensor groups to digital numbers; storing said digital numbers; determining first set of successive values of: ##EQU12## for successive values of p for positive values of F, and a second set of successive values of: ##EQU13## for successive values of p for negative values of F where i k are ones of said digital numbers corresponding to sensors of said first sensor group, j k are ones of said digital numbers corresponding to sensors of said second sensor group with k indicating sensor positions within said sensor groups, n is the number of sensors in each said sensor group, p=-1, 0, 1, 2, . . . P with P being an integer less than n, β 0 =A 0 /(n-1), β p+2 =A 0 /(n-p-1) and A 0 is a predetermined constant; determining values of F=F S and F=F S+1 where F S represents the value of F before a change in the sign of F and F S+1 represents the value of F after a change in the sign of F for successive values of p, and S corresponds to an image movement amount from a prior position to a position corresponding to the value of p before said change in sign of F; determining a value of M=S+F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said first set of values and M=S-F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said second set of values; and moving said lens directly from said prior position to a focused position determined in accordance with said value of M.

Claim 6

A method for automatically focusing a camera having a focusing lens, first and second sensor groups, and means for projecting images of an object transmitted through said focusing lens onto said first and second sensor groups, said method comprising; shifting at least one of said images on said sensor groups; converting outputs of said first and second sensor groups to digital numbers; storing said digital numbers; determining first set of successive values of: ##EQU12## for successive values of p for positive values of F, and a second set of successive values of: ##EQU13## for successive values of p for negative values of F where i k are ones of said digital numbers corresponding to sensors of said first sensor group, j k are ones of said digital numbers corresponding to sensors of said second sensor group with k indicating sensor positions within said sensor groups, n is the number of sensors in each said sensor group, p=-1, 0, 1, 2, . . . P with P being an integer less than n, β 0 =A 0 /(n-1), β p+2 =A 0 /(n-p-1) and A 0 is a predetermined constant; determining values of F=F S and F=F S+1 where F S represents the value of F before a change in the sign of F and F S+1 represents the value of F after a change in the sign of F for successive values of p, and S corresponds to an image movement amount from a prior position to a position corresponding to the value of p before said change in sign of F; determining a value of M=S+F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said first set of values and M=S-F S /(F S -F S+1 ) if said change in the sign of said value F occurs during said second set of values; and moving said lens directly from said prior position to a focused position determined in accordance with said value of M.