Focus detecting device

Claim 1

A focus detecting device for detecting the focus of an image-forming optical system onto an object, comprising: (A) image scanning means arranged to receive an image of the object formed by said image-forming optical system to produce a scanned signal of the image, said scanned signal having a plurality of constituent parts; and (B) a circuit system for receiving said scanned image signal produced by said image scanning means and for detecting, on the basis of the image signal, the focusing condition of the optical system onto the object, said circuit system including: (B-1) variation detecting means for receiving said scanned image signal and for producing a variation signal indicative of variations between constituent parts of said signal; (B-2) non-linear transformation means for non-linearly transforming said variation signal produced from said variation detecting means; and (B-3) integrating means for integrating the non-linearly transformed signal by said non-linear transformation means, an output of said integration means being indicative of the focusing condition of the optical system onto the object; said variation detecting means including: (B-1a) a delay circuit for receiving said scanned signal produced from said image scanning means and for delaying said image signal; and (B-1b) a difference detecting circuit for producing said variation signal by detecting the difference between the image signal delayed by said delay circuit and the image signal not delayed; said circuit system further comprising: signal level adjusting means between said variation detecting means and said non-linear transformation means to adjust the level of an input signal to said non-linear transformation means; and control means electrically coupled to said integrating means and signal level adjusting means to control said signal level adjusting means based on the output of said integrating means.

Claim 16

The device according to one of claims 1-14, wherein said image scanning means is a signal integration type image scanning means; and said circuit system further comprises: signal integration time control means for controlling a signal integration time of the image scanning means based on said scanned image signal produced from said image scanning means.

Claim 23

A device for detecting the positional relation of an image formed by an image-forming optical system with respect to a predetermined focal plane, comprising: (A) image scanning means having first and second groups of a plurality of scanning elements, said first scanning element group being arranged in a first position forwardly spaced from said predetermined focal plane by a predetermined distance upon receipt of the image formed by said image-forming optical system to produce a first scanned image signal concerning the image at said first position, said second scanning element group being arranged in a second position rearwardly spaced from said predetermined focal plane by a predetermined distance upon receipt of the image formed by said image-forming optical system to produce a second scanned image signal concerning the image at said second position, and said scanning means providing said first and second image signals sequentially, said scanned image signals having a plurality of constituent parts; and (B) a circuit system receiving said first and second scanned image signals provided by said image scanning means and detecting, on the basis of the image signals, the positional relation of the image formed by the optical system with respect to the predetermined focal plane, said circuit system comprising: (B-1) variation detecting means receptive of said first and second image signals for producing a variation signal indicative of the variations between constituent parts of said scanned image signals; (B-2) non-linear transformation means for non-linearly transforming said variation signal produced by said variation detecting means; (B-3) integration means coupled to said non-linear transformation means for integrating the signal non-linearly transformed by said non-linear transformation means, said integration means having operational means for performing non-inversion integration of a non-linear transformation signal of said first image signal and inversion integration of a non-linear transformation signal of said second image signal from said non-linear transformation means, and having output means for indicating the positional relation of the image formed by the optical system with respect to the predetermined focal plane.

Claim 24

A device for detecting the positional relation of an image formed by an image-forming optical system with respect to a predetermined focal plane, comprising: (A) image scanning means having first and second groups of a plurality of scanning elements, said first scanning element group being arranged in a first position forwardly spaced from said predetermined focal plane by a predetermined distance upon receipt of the image formed by said image-forming optical system to produce a first scanned image signal concerning the image at said first position, said second scanning element group being arranged in a second position rearwardly spaced from said predetermined focal plane by a predetermined distance upon receipt of the image formed by said image-forming optical system to produce a second scanned image signal concerning the image at said second position, and said scanning means providing said first and second image signals sequentially, said scanned image signals having a plurality of constituent parts; and (B) a circuit system receiving said first and second scanned image signals provided by said image scanning means and detecting, on the basis of the image signals, the positional relation of the image formed by the optical system with respect to the predetermined focal plane, said circuit system comprising: (B-1) variation detecting means receptive of said first and second image signals for producing a variation signal indicative of the variations between constituent parts of said scanned image signals; (B-2) non-linear transformation means for non-linearly transforming said variation signal produced by said variation detecting means; (B-3) integration means coupled to said non-linear transformation means for integrating the signal non-linearly transformed by said non-linear transformation means, said integration means having operational means for performing non-inversion integration of a non-linear transformation signal of said first image signal and inversion integration of a non-linear transformation signal of said second image signal from said non-linear transformation means, and having output means for indicating the positional relation of the image formed by the optical system with respect to the predetermined focal plane.

Claim 26

The device according to one of claims 17-20, 22 or 23, wherein said integration means comprises: an integration circuit for integrating the non-linearly transformed signal by said non-linear transformation means; said operational means includes: an inversion circuit for inverting the non-linear transformation signal from said non-linear transformation means concerning said second image signal; and a selection circuit for selectively applying the output signal of said non-linear transformation circuit and the output signal of said inversion circuit to said integration circuit.

Claim 33

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis and forming an image of said object whose position changes along said optical axis, said device comprising: (A) means for sensing said image and for producing an electrical signal corresponding to the radiation distribution of the image; (B) optical means for causing said sensing means to sense said image at a plurality of different positions along the optical axis and to produce image signals corresponding to the radiation distribution of the image at said respective positions; (C) means for determining the focusing condition of the optical system with respect to the object on the basis of said image signals produced by said image sensing means; and (D) means for adjusting the level of each of said electrical signals produced by said sensing means on the basis of the optical characteristic of said optical means prior to the supply of said electrical signals to said determining means.

Claim 34

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis and forming an image of said object whose position changes along said optical axis, said device comprising: (A) means for sensing said image and for producing an electrical signal corresponding to the radiation distribution of the image; (B) optical means for causing said sensing means to sense said image at a plurality of different positions along the optical axis and to produce image signals corresponding to the radiation distribution of the image at said respective positions; (C) means for determining the focusing condition of the optical system with respect to the object on the basis of said image signals produced by said image sensing means; and (D) means for adjusting the level of each of said electrical signals produced by said sensing means on the basis of the optical characteristic of said optical means prior to the supply of said electrical signals to said determining means.

Claim 36

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis for forming an image of said object whose position changes along said optical axis with respect to a predetermined focal plane, said device comprising: (A) means for forming electrical signals indicative of imaging conditions of said image at a plurality of different positions along the optical axis of the optical system, said positions including a first position a predetermined distance ahead of said focal plane and a second position the same distance behind the focal plane; and (B) means for determining the focusing condition of the optical system with respect to the object on the basis of said signals formed by said signal forming means, said determining means including: (B-1) means for forming a first signal corresponding to the difference between the signals indicative of the imaging conditions of said image at said first and second positions respectively; (B-2) means for forming a second signal to determine an in-focus range, the level of said second signal being changed in accordance with the changes in levels of said electrical signals formed by said signal forming means; and (B-3) means for discriminating the focusing condition of said optical system with respect to the object on the basis of said first signal formed by said first signal forming means and said second signal formed by said second signal forming means.

Claim 37

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis for forming an image of said object whose position changes along said optical axis with respect to a predetermined focal plane, said device comprising: (A) means for forming electrical signals indicative of imaging conditions of said image at a plurality of different positions along the optical axis of the optical system, said positions including a first position a predetermined distance ahead of said focal plane and a second position the same distance behind the focal plane; and (B) means for determining the focusing condition of the optical system with respect to the object on the basis of said signals formed by said signal forming means, said determining means including: (B-1) means for forming a first signal corresponding to the difference between the signals indicative of the imaging conditions of said image at said first and second positions respectively; (B-2) means for forming a second signal to determine an in-focus range, the level of said second signal being changed in accordance with the changes in levels of said electrical signals formed by said signal forming means; and (B-3) means for discriminating the focusing condition of said optical system with respect to the object on the basis of said first signal formed by said first signal forming means and said second signal formed by said second signal forming means.

Claim 41

The device according to claims 30, 31, 32, or 33, wherein said discriminating means produces an output indicative of the focusing condition of the optical system with respect to the object; and said determining means further includes means for controlling the output of said discriminating means on the basis of the level of said second signal formed by said second signal forming means.

Claim 43

The device according to claims 30, 31, or 32, wherein said second signal forming means is arranged to adjust the level of said second signal on the basis of various optical factors of said optical system.

Claim 44

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis for forming an image of said object whose position changes along said optical axis with respect to a predetermined focal plane, said device comprising: (A) means for time-sequentially forming electrical signals indicative of imaging conditions of said image at a plurality of different positions along the optical axis of the optical system respectively, said signal forming means including a plurality of image sensing means for sensing the image at the respective positions and for time-sequentially producing scanned image signals corresponding to the image at the respective positions and processing means for time-sequentially processing the scanned image signals and for time-sequentially producing said electrical signals indicative of the imaging conditions, said positions including a first position a predetermined distance ahead of the focal plane and a second position the same distance behind the focal plane; (B) means for discerning the focusing condition of the optical system with respect to the object on the basis of said signals formed time-sequentially by said signal forming means and producing an electrical output indicative of the focusing condition of the optical system; (C) means for controlling the output of said discerning means on the basis of said electrical signals formed by said signal forming means; said control means being arranged to control the output of said discerning means on the basis of the signals indicative of the imaging conditions of said image at said first and second positions; said control means being arranged to control the output of said discerning means according to the level of the sum of the signals indicative of the imaging conditions of the image at the first and second positions; said control means is arranged to inhibit the output of said discerning means when the level of said sum is below a predetermined level.

Claim 45

A device for detecting a focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis for forming an image of said object whose position changes along said optical axis with respect to a predetermined focal plane, said device comprising: (A) means for time-sequentially forming electrical signals indicative of imaging conditions of said image at a plurality of different positions along the optical axis of the optical system respectively, said signal forming means including a plurality of image sensing means for sensing the image at the respective positions and for time-sequentially producing scanned image signals corresponding to the image at the respective positions and processing means for time-sequentially processing the scanned image signals and for time-sequentially producing said electrical signals indicative of the imaging conditions, said positions including a first position a predetermined distance ahead of the focal plane and a second position the same distance behind the focal plane; (B) means for discerning the focusing condition of the optical system with respect to the object on the basis of said signals formed time-sequentially by said signal forming means and producing an electrical output indicative of the focusing condition of the optical system; (C) means for controlling the output of said discerning means on the basis of said electrical signals formed by said signal forming means; said control means being arranged to control the output of said discerning means on the basis of the signals indicative of the imaging conditions of said image at said first and second positions; said control means being arranged to control the output of said discerning means according to the level of the sum of the signals indicative of the imaging conditions of the image at the first and second positions; said control means is arranged to inhibit the output of said discerning means when the level of said sum is below a predetermined level.

Claim 47

A device for detecting the focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis and forming an image of said object whose position changes along the optical axis with respect to a predetermined focal plane, said device comprising: (A) means for forming electrical signals indicative of imaging conditions of the image at a plurality of different positions along the optical axis of the optical system, said positions including a first position a predetermined distance forward of the focal plane and second position the same distance to the rear of the focal plane; (B) discriminating means for determining the focusing condition of the optical system with respect to the object on the basis of said signals formed by said signal forming means, said discriminating means determining the focusing condition on the basis of the signals indicative of the imaging conditions of said image at said first and second positions between in-focus, near-focus, far-focus and extremely out-of-focus conditions and producing an electrical output indicating of the focusing condition of the optical system; (C) means for indicating the focusing condition of the optical system determined by said discriminating means; and (D) means responsive to the electrical output of the discriminating means to activate said indicating means for distinctly indicating each of said in-focus, near-focus, far-focus and extremely out-of-focus conditions.

Claim 48

A device for detecting the focusing condition of an image forming optical system with respect to an object, said optical system having an optical axis and forming an image of said object whose position changes along the optical axis with respect to a predetermined focal plane, said device comprising: (A) means for forming electrical signals indicative of imaging conditions of the image at a plurality of different positions along the optical axis of the optical system, said positions including a first position a predetermined distance forward of the focal plane and second position the same distance to the rear of the focal plane; (B) discriminating means for determining the focusing condition of the optical system with respect to the object on the basis of said signals formed by said signal forming means, said discriminating means determining the focusing condition on the basis of the signals indicative of the imaging conditions of said image at said first and second positions between in-focus, near-focus, far-focus and extremely out-of-focus conditions and producing an electrical output indicating of the focusing condition of the optical system; (C) means for indicating the focusing condition of the optical system determined by said discriminating means; and (D) means responsive to the electrical output of the discriminating means to activate said indicating means for distinctly indicating each of said in-focus, near-focus, far-focus and extremely out-of-focus conditions.

Claim 50

A device for indicating the focusing condition of an optical system with respect to an object, comprising: (A) discriminating means for determining the focusing condition of the optical system with respect to the object between the in-focus, near-focus, far-focus, and extremely out-of-focus conditions and producing an electrical output indicative of the focusing condition of the optical system; (B) means for indicating the focusing condition of the optical system determined by said discriminating means; and (C) means responsive to the electrical output of the discriminating means to activate said indicating means for distinctly indicating each of said in-focus, near-focus, far-focus, and extremely out-of-focus conditions.

Claim 51

A device for indicating the focusing condition of an optical system with respect to an object, comprising: (A) discriminating means for determining the focusing condition of the optical system with respect to the object between the in-focus, near-focus, far-focus, and extremely out-of-focus conditions and producing an electrical output indicative of the focusing condition of the optical system; (B) means for indicating the focusing condition of the optical system determined by said discriminating means; and (C) means responsive to the electrical output of the discriminating means to activate said indicating means for distinctly indicating each of said in-focus, near-focus, far-focus, and extremely out-of-focus conditions.