Focus apparatus and digital filters for use therewith

Claim 2

A focusing control apparatus for a video camera in which middle high frequency components in a video signal are detected for focusing by maximizing the middle high frequency components, comprising: lens means 1 for focusing an image; motive means 2 for moving said lens means; image pickup means 3 for converting light from said lens means 1 into electrical signals; signal processing means 4 for processing the electrical signals from said image pickup means 3 to obtain analog luminance signals; analog to digital converter means 5 for converting analog luminance signals from said signal processing means 4 into digital luminance signals; filter means 6 including a low pass filter 7 for imparting characteristics to the digital luminance signals corresponding substantially to characteristics of said image produced when said lens 1 is out of focus, and subtracting means 8 for eliminating signal components which pass through said filter 6 from said digital luminance signals to produce a filtered output signal; detecting means 9 for detecting the level of said filtered output signal from the subtracting means 8 and providing a corresponding detected output signal; integrating means 10 for integrating said detected output signal and providing an integrated output signal; driving means 12 for driving said motive means 2 in accordance with a control signal; and control means 11 for providing said control signal to said driving means such that said lens means 1 is positioned to maximize said integrated output signal.

Claim 3

A focusing control apparatus according to claim 1, wherein said filter means comprises: a cascade connection of an (m) sample long delay circuit 52 and an (m + 1) sample long delay circuit 53; first subtracting circuit 54 means for forming an output representing the difference of said digital luminance signal and a preceding value thereof transmitted through said cascade connection of the (m) sample long delay circuit 52 and the (m + 1) sample long delay circuit 53; multiplying means 55 for multiplying an output signal from a common node of the (m) sample long delay circuit 52 and the (m + 1) sample long delay circuit 53 by a coefficient (2m); first adding means 56 for adding the output signal from the common node of the (m) sample long delay circuit 52 and the (m + 1) sample long delay circuit 53 and an output signal of said multiplying means 55; second adding means 57 having a first input coupled to receive the output of said first subtracting means 54, a second input, and an output; a one-sample long delay circuit 59 having an input coupled with the output of the second adding means 57 and an output coupled with said second input of said second adding means 57; and second subtracting circuit means 58 for subtracting an output signal of said first adding means 56 and an output signal of said second adding means 57 to provide said filtered output signal.

Claim 4

A focusing control apparatus according to claim 1, wherein said filter means comprises: a cascade connection of an (m + 1) sample delay circuit 62 and an (m) sample long delay circuit 63; first subtracting circuit means 64 for subtracting said digital luminance signal and a preceding value thereof transmitted through said cascade connection of the (m + 1) sample delay circuit 62 and the (m) sample long delay circuit 63; first one-sample delay means 71 for latching an output signal of said first subtracting circuit means 64; multiplying means 65 for multiplying an output signal from a common node of the (m + 1) sample long delay circuit 62 and the (m) sample long delay circuit 63 by a coefficient (2m); first adding means 66 for adding the output signal from the common node of the (m + 1) sample long delay circuit 62 and the (m) sample delay circuit 63 and an output signal of said multiplying means; second one-sample delay means 72 latching an output signal of said first adding means 66; second adding means 67 for adding signals received at first and second inputs thereof to produce an output signal at an output thereof representing the sum of the input signals, said first input receiving said signal latched by the first one-­sample delay means 71; third one-sample delay means 69 coupled with the output of the second adding means 67 for latching the output signal thereof and having an output coupled with the second input of said second adding means 67; and second subtracting circuit means 68 for subtracting an output signal of said third one-sample delay means 69 and an output signal of said second one-sample delay means 72 to provide said filtered output signal

Claim 5

A focusing control apparatus according to claim 1, wherein said filter means comprises: a cascade connection of an (m - 1) sample delay circuit 82, a first one-sample delay circuit 83 and an (m) sample delay circuit 84; first multiplying means 86 for multiplying a signal provided at a common node of said (m - 1) sample delay circuit 82 and said first one-sample delay circuit 83 by a coefficient (m); second multiplying means 88 for multiplying a signal provided at a common node of said first one-sample delay circuit 83 and said (m) sample delay circuit 84 by a coefficient (m); first subtracting circuit means 85 for subtracting said digital luminance signal and a preceding value thereof transmitted through said (m - 1) sample delay circuit 82, said first one-sample delay circuit 83 and said (m) sample delay circuit 84; first adding means 87 for adding an output signal of said first multiplying means 86 and an output signal of said second multiplying means 88; second adding means 90 for adding signals received at first and second inputs thereof to produce an output signal at an output thereof representing the sum of the input signals, said first input of the second adding means 90 being coupled to receive an output signal of said first subtracting circuit means 85; a second one-sample delay circuit 91 coupled with the output of the second adding means 90 for delaying the output thereof by one-sample period and providing said one-sample period delayed output to the second input of said second adding means 90; and second subtracting circuit means 89 for subtracting an output signal of said first adding means 87 and an output signal of said second adding means 90 to provide said filtered output signal.

Claim 8

The system according to claim 5, wherein said signal filtering means 6 includes low pass filtering means 7 for passing components of said video signals having characteristics corresponding to characteristics of said image produced when said lens is out of focus; and subtracting means 8 for eliminating said components of said video signals passed by said low pass filtering means 7 from said video signals to produce said focusing signal.

Claim 9

The system according to claim 6, further comprising integrating means 10 for integrating said focusing signal.

Claim 10

The system according to claim 6 or 7, wherein said image pickup means is operative to produce an analog video signal; and further comprising analog to digital converter means 5 for converting said analog video signal to a digital video signal, and means for supplying said digital video signal to said low pass filtering means 7 and to said subtracting means 8.

Claim 11

The system according to claim 5, wherein said signal filtering means includes: low pass filtering means 7 coupled to receive said video signal for attenuating high frequency components thereof to produce a low pass filtered signal having characteristics corresponding to characteristics of said image produced by said lens when it is out of focus; and means 8 for subtracting said low pass filtered signal from said video signal to produce said focusing signal.

Claim 12

The system according to claim 9, further comprising: analog to digital converter means 5 for converting said video signal to a digital video signal; and wherein said low pass filtering means 7 comprises a digital averaging low pass filter receiving said digital video signal.

Claim 13

The system according to claim 5, further comprising analog to digital converter means for converting said video signal to a digital video signal; and wherein said signal filtering means 6 includes digital signal filtering means for providing said focusing signal in a digital signal format based on said digital video signal.

Claim 14

The system according to claim 11, wherein said digital signal filtering means includes: means 33,34 for producing a first digital signal proportional to the difference between said digital video signal and a preceding value of said digital video signal delayed in time by (2m + 1) sample periods with respect to said digital video signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 32,35 for producing a third digital signal proportional to a value of said digital video signal delayed in time by (m) sample periods with respect to said digital video signal and multiplied by a coefficient (2m + 1); and means 36 for adding said second digital signal and said third digital signal to produce said focusing signal.

Claim 15

The system according to claim 11, wherein said digital signal filtering means includes: means 33,34 for producing a first digital signal proportional to a difference between said digital video signal and a preceding value of said digital video signal delayed in time by (2m + 1) sample periods with respect to said digital video signal; means for integrating said first digital signal to produce a second digital signal; means for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means for producing a fourth digital signal proportional to a value of said digital video signal delayed in time by (m + 1) sample periods with respect to said digital video signal and multiplied by a coefficient (2m + 1); and means for adding said third digital signal and said fourth digital signal to produce said focusing signal.

Claim 16

The system according to claim 11, wherein said digital signal filtering means includes: means 22 for producing a first digital signal proportional to a difference between said digital video signal and a preceding value of said digital signal delayed in time by (2m) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means, 102,103,107 for producing a third digital signal proportional to (m) times a sum of a value of said digital video signal delayed by (m-1) sample periods and a value of said digital video signal delayed by (m) sample periods; and means for adding said second digital signal and said third digital signal to produce said focusing signal.

Claim 17

The system according to claim 11, wherein said digital signal filtering means includes: means 12 for producing a first digital signal proportional to a difference between said digital video signal and a preceding value of said digital video signal delayed in time by (2m) sample periods with respect to said digital video signal, where (m) in an integer; means for integrating said first digital signal to produce a second digital signal; means for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means for producing a fourth digital signal proportional to a sum of a value of said digital video signal delayed by (m + 1) sample periods multiplied by a coefficient (m) and (122,126) a value of said digital video signal delayed by (m) sample periods multiplied by a coefficient (m); and adding means for adding said third digital signal and said fourth digital signal to produce said focusing signal.

Claim 18

A digital signal filter for filtering a digital input signal, comprising: means 33,34 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m + 1) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 32, 38 for producing a third digital signal proportional to a value of said input digital signal delayed in time by (m) sample periods with respect to said input digital signal and multiplied by a coefficient (2m + 1); and means 36 for adding said second digital signal and said third digital signal to produce a filtered digital output signal.

Claim 19

A digital signal filter for filtering a digital input signal, comprising: means 33,34 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m + 1) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 32, 38 for producing a third digital signal proportional to a value of said input digital signal delayed in time by (m) sample periods with respect to said input digital signal and multiplied by a coefficient (2m + 1); and means 36 for adding said second digital signal and said third digital signal to produce a filtered digital output signal.

Claim 20

A digital signal filter according to claim 16, wherein said means for producing a first digital signal and said means for producing a third digital signal share a common (m) sample period delay means 52; and wherein said means for producing a third digital signal includes: bit shifting means 55 coupled with said common (m) sample period delay means to receive an (m) sample period delayed value of said digital input signal for providing an output signal proportional to said (m) sample period delayed value multiplied by a coefficient (2m); and adding means 56 for adding said output signal of said bit shifting means 55 and said (m) sample period delayed value to produce said third digital signal.

Claim 21

A digital signal filter for filtering a digital input signal, comprising: means 33 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m + 1) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means for producing a fourth digital signal proportional to a value of said digital input signal delayed in time by (m + 1) sample periods with respect to said digital input signal and multiplied by a coefficient (2m + 1); and adding means for adding said third digital signal and said fourth digital signal to produce a filtered digital output signal.

Claim 22

A digital signal filter for filtering a digital input signal, comprising: means 33 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m + 1) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means for producing a fourth digital signal proportional to a value of said digital input signal delayed in time by (m + 1) sample periods with respect to said digital input signal and multiplied by a coefficient (2m + 1); and adding means for adding said third digital signal and said fourth digital signal to produce a filtered digital output signal.

Claim 23

A digital signal filter according to claim 18, wherein said means for producing a first digital signal and said means for producing a fourth digital signal share a common (m + 1) sample period delay means 62; and wherein said means for producing a fourth digital signal includes: bit shifting means 65 coupled with said common (m + 1) sample period delay means to receive an (m + 1) sample period delayed value of said digital input signal for providing an output signal proportional to said (m + 1) sample period delayed value multiplied by a coefficient of (2m); and second adding means 66 for adding said output signal of said bit shifting means and said (m + 1) sample period delayed value to produce said third digital signal.

Claim 24

A digital signal filter according to claim 18, wherein said means for producing the second and third digital signals includes: second adding means 67 for adding digital signals provided at first and second inputs thereof, said first input of the second adding means being coupled to receive the first digital signal; and delay means 69 for providing an output signal at an output thereof proportional to a signal provided at an input thereof and delayed by one sample period; the input of the delay means 69 being coupled with the output of the second adding means 67 and the output of the delay means 69 being coupled with the second input of the second adding means 67 and with the first mentioned adding means 68 to supply the output of said delay means 69 thereto as said third digital signal.

Claim 25

A digital signal filter for filtering a digital input signal, comprising: means 82-85 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 82,83,86,87,88 for producing a third digital signal proportional to (m) times a sum of a value of said input digital signal delayed by (m - 1) sample periods and a value of said input digital signal delayed by (m) sample periods; and adding means 89 for adding said second digital signal and said third digital signal to produce a filtered digital output signal.

Claim 26

A digital signal filter for filtering a digital input signal, comprising: means 82-85 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 82,83,86,87,88 for producing a third digital signal proportional to (m) times a sum of a value of said input digital signal delayed by (m - 1) sample periods and a value of said input digital signal delayed by (m) sample periods; and adding means 89 for adding said second digital signal and said third digital signal to produce a filtered digital output signal.

Claim 27

The digital signal filter according to claim 21, wherein the means for producing a third digital signal includes: first delay means 82 for delaying said digital input signal by (m - 1) sample periods to produce a fourth digital signal; first multiplying means 86 for multiplying said fourth digital signal by a coefficient (m) to produce a fifth digital signal; second delay means 83 for delaying the fourth digital signal by one sample period to produce a sixth digital signal; second multiplying means 88 for multiplying said sixth digital signal by a coefficient (m) to produce a seventh digital signal; and second adding means 87 for adding said fifth digital signal and said seventh digital signal to produce said third digital signal.

Claim 28

The digital signal filter according to claim 21, wherein the means for producing a third digital signal includes: first delay means 102 for delaying said digital input signal by (m - 1) sample periods to produce a fourth digital signal; second delay means 103 for delaying said fourth digital signal by one sample period to produce a fifth digital signal; second adding means 107 for adding said fourth digital signal and said fifth digital signal to produce a sixth digital signal; and means 106 for multiplying the sixth digital signal by a coefficient (m) to produce said third digital signal.

Claim 29

A digital signal filter for filtering a digital input signal, comprising: means 122-125 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 134 for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means 122, 123, 126, 127, 128 for producing a fourth digital signal proportional to a sum of a value of said digital input signal delayed by (m + 1) sample periods multiplied by a coefficient (m) and a value of said digital input signal delayed by (m) sample periods multiplied by a coefficient (m); and adding means 129 for adding said third digital signal and said fourth digital signal to produce a filtered digital output signal.

Claim 30

A digital signal filter for filtering a digital input signal, comprising: means 122-125 for producing a first digital signal proportional to a difference between said digital input signal and a preceding value of said digital input signal delayed in time by (2m) sample periods with respect to said digital input signal, where (m) is an integer; means for integrating said first digital signal to produce a second digital signal; means 134 for producing a third digital signal proportional to a value of said second digital signal delayed in time by one sample period; means 122, 123, 126, 127, 128 for producing a fourth digital signal proportional to a sum of a value of said digital input signal delayed by (m + 1) sample periods multiplied by a coefficient (m) and a value of said digital input signal delayed by (m) sample periods multiplied by a coefficient (m); and adding means 129 for adding said third digital signal and said fourth digital signal to produce a filtered digital output signal.

Claim 31

The digital signal filter according to claim 24, wherein the means for producing the fourth digital signal includes: first delay means 122 for delaying said digital input signal by (m) sample periods to produce a fifth digital signal; first multiplying means 126 for multiplying said fifth digital signal by a coefficient (m) to produce a sixth digital signal; second delay means 123 for delaying said fifth digital signal by one sample period to produce a seventh digital signal; second multiplying means 128 for multiplying said seventh digital signal by a coefficient (m) to produce an eighth digital signal; and second adding means 127 for adding said sixth digital signal and said eighth digital signal to produce said fourth digital signal.

Claim 32

The digital signal filter of claim 24, wherein the means for producing the fourth digital signal includes: first delay means 142 for delaying said digital input signal by (m) sample periods to produce a fifth digital signal; second delay means 143 for delaying said fifth digital signal by one sample period to produce a sixth digital signal; second adding means 147 for adding said fifth digital signal and said sixth digital signal to produce a seventh digital signal; and multiplying means 146 for multiplying said seventh digital signal by a coefficient (m) to produce said fourth digital signal.

Claim 33

The digital signal filter of claim 24, wherein said means for integrating said first digital signal and said means for producing a third digital signal include: second adding means 130; 150 for adding signals provided at first and second inputs thereof to produce a summation signal, said first input of said second adding means being coupled with said means for producing a first digital signal to receive said first digital signal therefrom; and delay means 131; 151 for delaying said summation signal by one sample period and supplying the resulting delayed summation signal to said second input of said second adding means, said delay means being also connected to the first-mentioned adding means 129; 149 to provide said one sample delayed summation signal thereto as said third digital signal.