Method and apparatus for determining focus direction and amount

Claim 1

Apparatus for use with an auto focus system which includes lens means that produces first and second radiation distribution patterns of a scene to be focused upon, the patterns being similar and in a first relative position when the lens means is in a proper focus position with respect to the scene, the patterns moving away from the first relative position in a first relative direction as the relative position of the scene and the lens means changes from the proper focus position in one direction and the patterns mov-ing away from the first relative position in a second relative direction as the relative position of the scene and the lens means changes from the proper focus position in a direction opposite to the one direction comprising, in combination: a first plurality of radiation detectors positioned to receive the first radiation distribution pattern, each radiation detector in the first plurality of radiation detectors operable to produce an output indicative of the radiation received thereby; a second plurality of radiation detectors positioned to receive the second radiation distribution pattern, each radiation detector in the second plurality of radiation detectors operable to produce an output indicative of the radiation received thereby, each radiation detector in the second plurality of radiation detectors having a positionally corresponding radiation detector in the first plurality of radiation detectors so that, when the lens means is in a proper focus position, the output of each radiation detector in the second plurality of radiation detectors is substantially equal to the output of its positionally corresponding radiation detector in the first plurality of radiation detectors; shift register means connected to receive the outputs of the radiation detectors in the first and second plurality of radiation detectors and operable to shift the outputs of the radiation detectors in one of the plurality of radiation detectors with respect to the outputs of the positionally corresponding radiation detectors in the other of the plurality of radiation detectors; signal receiving means connected to the shift reg-ister means to receive the outputs of the radiation detec-tors in the first and second plurality of radiation detec-tors and to produce a plurality of consecutive outputs, Vi, in accordance with the expression Vi = where N is the number of radiation detectors in the first plurality of radiation detectors, n is any number from 1 to N, a represents the output of individual radiation detectors in the first plurality of radiation detectors, b represents the output of individual radiation detectors in the second plurality of radiation detectors and i represents the number of shifts of the shift register from -N/2 to +N/2; difference means connected to the signal receiving means to receive each two consecutive values of Vi and to produce consecutive outputs, Di, representative of the dif-ference therebetween; storage means connected to the difference means to receive and store the outputs Di; comparator means connected to the storage means to receive the latest value of Di and the largest Di value pre-viously stored in the storage means and to produce an output DL representative of the largest Di compared; means connecting the comparator means to the storage means to substitute the DL output for the largest Di value previously stored in the storage means; and signal processing means connected to the storage means to receive the largest DL signal, Dm, when i = +N/2 and to produce an output, L.E., indicative of P(Vm/Dm +im) where P is a constant proportional to the distance between radiation detectors in the first and second plurality of radiation detectors, and Vm and are are the Vi and i values when the DL value is equal to Dm .

Claim 6

The method for determining the direction and amount a lens of a camera should be moved in order to achieve the proper focus position with respect to a remote object which camera includes lens means that produces first and second radiation distribution patterns of the scene, and a plurali-ty N of positionally corresponding radiation detector pairs, a first detector in each pair being identified as an a detector and the second detector in each pair being identified as a b detector and the detector pairs being mounted to receive radiation from the remote scene with the a detectors receiving radiation in the first radiation dis-tribution pattern and the b detectors receiving radiation in the second radiation distribution pattern comprising the following steps: Step 1 - presenting the outputs from all of the a and b detectors to a memory for storage; Step 2 - shifting the outputs of the b detectors a number of positions with respect to the a positionally corresponding detectors in a first direction, Step 3 - determining a value Vi from the shifted outputs of the b detectors and the outputs of the a detec-tors in accordance with the equation Vi = (1) where i represents the number of shifts of the b detector outputs with respect to the positionally corresponding a detector outputs; Step 4 - storing the value Vi and the i value with which it is associated; Step 5 - shifting the b outputs one position in a direction opposite to the first direction with respect to the positionally corresponding a outputs; Step 6 - determining a new Vi from the above equa-tion (1) and storing the new Vi and i values; Step 7 - subtracting the first and second Vi values to obtain a first Di value; Step 8 - storing the value Di and the Vi and i values with which it is associated; Step 9 - repeating Steps 5 through 8 to obtain a new Di value; Step 10 - comparing the old Di and the new Di value to determine which is largest and storing the largest Di value and the corresponding Vi and i values with which it is associated; Step 11 - repeating Steps 5 through 10 until i = +N/2 at which time the largest D value, Dm, and the Vi and i values with which it is associated (Vm and im) are stored, and Step 12 - determining the lens extension value from the equation L.E. = P (Vm/Dm + im) where P is a constant representing the lens extension per shift.

Claim 7

The method for determining the direction and amount a lens of a camera should be moved in order to achieve the proper focus position with respect to a remote object which camera includes lens means that produces first and second radiation distribution patterns of the scene, and a plurali-ty N of positionally corresponding radiation detector pairs, a first detector in each pair being identified as an a detector and the second detector in each pair being identified as a b detector and the detector pairs being mounted to receive radiation from the remote scene with the a detectors receiving radiation in the first radiation dis-tribution pattern and the b detectors receiving radiation in the second radiation distribution pattern comprising the following steps: Step 1 - presenting the outputs from all of the a and b detectors to a memory for storage; Step 2 - shifting the outputs of the b detectors a number of positions with respect to the a positionally corresponding detectors in a first direction, Step 3 - determining a value Vi from the shifted outputs of the b detectors and the outputs of the a detec-tors in accordance with the equation Vi = (1) where i represents the number of shifts of the b detector outputs with respect to the positionally corresponding a detector outputs; Step 4 - storing the value Vi and the i value with which it is associated; Step 5 - shifting the b outputs one position in a direction opposite to the first direction with respect to the positionally corresponding a outputs; Step 6 - determining a new Vi from the above equa-tion (1) and storing the new Vi and i values; Step 7 - subtracting the first and second Vi values to obtain a first Di value; Step 8 - storing the value Di and the Vi and i values with which it is associated; Step 9 - repeating Steps 5 through 8 to obtain a new Di value; Step 10 - comparing the old Di and the new Di value to determine which is largest and storing the largest Di value and the corresponding Vi and i values with which it is associated; Step 11 - repeating Steps 5 through 10 until i = +N/2 at which time the largest D value, Dm, and the Vi and i values with which it is associated (Vm and im) are stored, and Step 12 - determining the lens extension value from the equation L.E. = P (Vm/Dm + im) where P is a constant representing the lens extension per shift.