US5321459A — Automatic focusing device

Claim 1

Independent Claim 185 words

An automatic focusing device, comprising: a focus lens that is movable along an optical axis thereof; drive means for driving said focus lens; distance measuring means for obtaining a defocus amount of said focus lens with respect to a photographing object image; measurement control means for controlling said distance measuring means to repeat distance measurements in a predetermined interval; computing means for computing a relative speed of movement of said photographing object image with respect to said focus lens along said optical axis, based upon defocus amounts obtained by said distance measuring means; means for determining whether a speed of movement of said photographing object image, as computed by said computing means, exceeds a predetermined value; and drive control means for controlling said drive means to drive said focus lens to a position where an in-focus condition is obtainable with respect to said photographing object after an elapse of a predetermined time, based upon computation results by said computing means when said determining means determines a predetermined number of consecutive times that said speed of movement of said photographing object image exceeds said predetermined value.

Claim 2

Dependent Claim 185 words

An automatic focusing device, comprising: a focus lens that is movable along an optical axis thereof; drive means for driving said focus lens; distance measuring means for obtaining a defocus amount of said focus lens with respect to a photographing object image; measurement control means for controlling said distance measuring means to repeat distance measurements in a predetermined interval; computing means for computing a relative speed of movement of said photographing object image with respect to said focus lens along said optical axis, based upon defocus amounts obtained by said distance measuring means; means for determining whether a speed of movement of said photographing object image, as computed by said computing means, exceeds a predetermined value; and drive control means for controlling said drive means to drive said focus lens to a position where an in-focus condition is obtainable with respect to said photographing object after an elapse of a predetermined time, based upon computation results by said computing means when said determining means determines a predetermined number of consecutive times that said speed of movement of said photographing object image exceeds said predetermined value.

Claim 3

Dependent Claim 37 words

The automatic focusing device of claim 1, wherein said speed of movement of said photographing object image is detected as a speed of movement of an image position thereof on an imaging plane of said focus lens.

Claim 4

Dependent Claim 55 words

The automatic focusing device of claim 1, wherein said predetermined time is a sum of a time required for obtaining said defocus amount by said distance measuring means and a time required for executing said lens drive by said drive control means, in case said photographing object image is moving away from said focus lens.

Claim 5

Dependent Claim 64 words

The automatic focusing device according to claim 1, wherein said predetermined time is the total sum of the time required for obtaining said defocus amount by said distance measuring means, the time required for executing said lens drive by said drive control means, and a certain additional time from completion of the lens drive in case the object is approaching to said focus lens.

Claim 6

Dependent Claim 17 words

The automatic focusing device of claim 1, wherein said in-focus condition is provided with a predetermined allowance.

Claim 7

Dependent Claim 39 words

The automatic focusing device of claim 1, further comprising means for checking whether said defocus amount obtained by said distance measuring means is effective; and wherein said drive control means is disabled if said checked defocus amount is ineffective.

Claim 8

Dependent Claim 32 words

A camera which employs said automatic focusing device as defined in claim 4, wherein said certain time comprises a release-time-lag that occurs between a shutter operation and a start of an exposure.

Claim 9

Dependent Claim 29 words

The camera of claim 7, wherein an additional lens drive amount corresponding to said release-time-lag is obtained by averaging release-time-lags that are consecutively obtained a predetermined number of times.

Claim 10

Dependent Claim 131 words

An automatic focusing device, comprising: means for obtaining a defocus amount of a lens with respect to an object; means for controlling said obtaining means to repeat obtaining said defocus amount at a predetermined interval; means for computing a speed of movement of an image of said object based upon defocus amounts obtained by said obtaining means; means for determining whether said speed of movement of said image of said object, as computed by said computing means, exceeds a predetermined value; and means for driving said lens to a position where an in-focus condition is obtained with respect to said image of said object after a predetermined period of time elapses, when said determining means determines that said speed of movement of said image of said object exceeds a predetermined value.

Claim 11

Dependent Claim 131 words

An automatic focusing device, comprising: means for obtaining a defocus amount of a lens with respect to an object; means for controlling said obtaining means to repeat obtaining said defocus amount at a predetermined interval; means for computing a speed of movement of an image of said object based upon defocus amounts obtained by said obtaining means; means for determining whether said speed of movement of said image of said object, as computed by said computing means, exceeds a predetermined value; and means for driving said lens to a position where an in-focus condition is obtained with respect to said image of said object after a predetermined period of time elapses, when said determining means determines that said speed of movement of said image of said object exceeds a predetermined value.

Claim 12

Dependent Claim 33 words

The automatic focusing device of claim 9, wherein said speed of movement of image as said said object is detected as a speed of movement of an image position on an imaging plane.

Claim 13

Dependent Claim 48 words

The automatic focusing device of claim 9, wherein said predetermined period of time is equal to a sum of a first time period required for obtaining said defocus amount and a second time period required for executing said lens drive when said object moves away from said lens.

Claim 14

Dependent Claim 58 words

The automatic focusing device of claim 9, wherein said predetermined period of time is equal to a sum of a first time period required for obtaining said defocus amount, a second time period for executing said lens drive, and a third time period that is measured from a completion of lens drive when said object approaches said lens.

Claim 15

Dependent Claim 15 words

The automatic focusing device of claim 12, wherein said third time period comprises a release-time-lag.

Claim 16

Dependent Claim 35 words

The automatic focusing device of claim 9, further comprising means for checking whether said defocus amount obtained by said obtaining means is effective, said driving means being disabled when said checked defocus amount is ineffective.

Claim 17

Independent Claim 102 words

A method for automatically focusing upon an object, comprising the steps of: obtaining a plurality of defocus amounts of a lens with respect to an object; computing a speed of movement of an image of the object based upon the plurality of obtained defocus amounts; determining whether the speed of movement of the object image exceeds a predetermined value; and driving the lens to a position where an in-focus condition is obtained with respect to the object image after a predetermined period of time elapses, when it is determined that the speed of movement of the object image exceeds a predetermined value.

Claim 18

Independent Claim 102 words

A method for automatically focusing upon an object, comprising the steps of: obtaining a plurality of defocus amounts of a lens with respect to an object; computing a speed of movement of an image of the object based upon the plurality of obtained defocus amounts; determining whether the speed of movement of the object image exceeds a predetermined value; and driving the lens to a position where an in-focus condition is obtained with respect to the object image after a predetermined period of time elapses, when it is determined that the speed of movement of the object image exceeds a predetermined value.

Claim 19

Dependent Claim 33 words

The method of claim 15, further comprising the step of checking whether the obtained defocus amounts are effective, the step of driving the lens being terminated when a checked defocus amount is ineffective.

Claim 20

Dependent Claim 147 words

An automatic focusing device, comprising: a lens that is movable along an optical axis thereof; a driver for driving said lens along said optical axis; a focus measuring unit for obtaining a plurality of defocus amounts of said lens with respect to an object; a computation unit that computes a speed of movement of an image of said object in response to said plurality of obtained defocus amounts; a discrimination unit that determines whether said computed speed of movement of said image of said object exceeds a predetermined value; and a controller that controls said driver to drive said lens to a position where an in-focus condition is obtained with respect to said image of said object after an elapse of a predetermined period of time when said discrimination means determines that said computed speed of movement of said image of said object exceeds a predetermined value.

Claim 21

Dependent Claim 147 words

An automatic focusing device, comprising: a lens that is movable along an optical axis thereof; a driver for driving said lens along said optical axis; a focus measuring unit for obtaining a plurality of defocus amounts of said lens with respect to an object; a computation unit that computes a speed of movement of an image of said object in response to said plurality of obtained defocus amounts; a discrimination unit that determines whether said computed speed of movement of said image of said object exceeds a predetermined value; and a controller that controls said driver to drive said lens to a position where an in-focus condition is obtained with respect to said image of said object after an elapse of a predetermined period of time when said discrimination means determines that said computed speed of movement of said image of said object exceeds a predetermined value.

Claim 22

Dependent Claim 48 words

The automatic focusing device of claim 17, wherein said predetermined period of time is equal to a sum of a first time period required for obtaining said defocus amount and a second time period required for executing said lens drive when said object moves away from said lens.

Claim 23

Dependent Claim 59 words

The automatic focusing device of claim 17, wherein said predetermined period of time is equal to a sum of a first time period required for obtaining said defocus amount, a second time period for executing said lens drive, and a third time period that is measured from a completion of said lens drive when said object approaches said lens.

Claim 24

Dependent Claim 38 words

The automatic focusing device of claim 17, further comprising a checker that determines whether said plurality of defocus amounts obtained by said focus measuring unit is effective, said driver being disabled when a checked defocus amount is ineffective.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-06-13	1997-12-13	1998-06-14	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-06-13	2001-12-13	2002-06-14	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-06-13	2005-12-13	2006-06-14	$7700.00	Window Closed / Lapsed

Automatic focusing device

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