EP0533590A2 — Distance measuring method and apparatus

Claim 1

Independent Claim 191 words

A method of obtaining distance data from an object to a lens by obtaining an image of the object by an image input unit for forming an image of the object through the lens on an image receiving plane and then performing a process, comprising steps of; inputting (S1, S3) two observed images Is and Is′ with different blurs from the said Image input unit by making a position of the lens, a position of the Image receiving plane or positions of both of them with regard to the object different by a minute distance Δz on the same optical axis; performing a filtering process (S2, S4) by applying filtering to the said two input observed images Is and Is′, thereby providing two output images Fs and Fs′; and calculating (S5) the distance a up to the object by using two output images Fs and Fs′ obtained by the filtering process based on the relation between said two output Images Fs and Fs′ and a radius s of the blur and the relation between the radius s of the blur and the distance a from the lens up to the object.

Claim 2

Independent Claim 191 words

A method of obtaining distance data from an object to a lens by obtaining an image of the object by an image input unit for forming an image of the object through the lens on an image receiving plane and then performing a process, comprising steps of; inputting (S1, S3) two observed images Is and Is′ with different blurs from the said Image input unit by making a position of the lens, a position of the Image receiving plane or positions of both of them with regard to the object different by a minute distance Δz on the same optical axis; performing a filtering process (S2, S4) by applying filtering to the said two input observed images Is and Is′, thereby providing two output images Fs and Fs′; and calculating (S5) the distance a up to the object by using two output images Fs and Fs′ obtained by the filtering process based on the relation between said two output Images Fs and Fs′ and a radius s of the blur and the relation between the radius s of the blur and the distance a from the lens up to the object.

Claim 3

Dependent Claim 119 words

2 The method of measuring the distance according to Claim 1 wherein the said filtering processes are designated by the following expressions (A) and (B); Fs=∫ exp(-x²/σ²)exp(ikx)Is(x)dx Fs′=∫ exp(-x²/σ²)exp(ikx)Is′(x)dx where k represents a certain predetermined frequency and σ a distribution. And the relation between the two output Images Fs and Fs′ and the radius s of the blur is represented by the following expression (C); (Fs′-Fs) (Δz)Fs = ks cos(ks)-sin(ks) sin(ks) s fΓ and the relation between the radius s of the blur and the distance a from the lens to the object is expressed by the following expression (D); s= Γf a where Γ represents a radius of the lens and f a focus distance of the lens.

Claim 4

Dependent Claim 52 words

The method of measuring the distance according to Claim 1 wherein the said distance data calculating process calculates (S6) the distance data by referring to a look-up-table which is previously prepared to represent a relation between the calculation value of the said expression (C) and the distance a up to the object.

Claim 5

Dependent Claim 196 words

A distance measuring apparatus comprising: an image input means (1, 6, 11, 21, 31, 41) comprising a lens and an image receiving plane for obtaining the observed image of the object on the image receiving plane and outputting the observed image; a first operating means (52 , 63) for applying a filtering process to the first image input from the said image input means thereby performing a Fourier transformation for a respective predetermined frequency k; a second operation means (52, 64) for applying the same operation as that of the first operation means to the second observed image which is obtained from the image input means when at least one of the lens position, the position of the image receiving plane, and the position of the image Input means Is moved; and a third operation means (2, 3) for obtaining the distance up to the object based on the results of the first operating means for the first observed Image, the result of the second operation means for the second observed image and the distance in which the said at least one of the lens, the image receiving plane and the image input means are moved.

Claim 6

Dependent Claim 196 words

A distance measuring apparatus comprising: an image input means (1, 6, 11, 21, 31, 41) comprising a lens and an image receiving plane for obtaining the observed image of the object on the image receiving plane and outputting the observed image; a first operating means (52 , 63) for applying a filtering process to the first image input from the said image input means thereby performing a Fourier transformation for a respective predetermined frequency k; a second operation means (52, 64) for applying the same operation as that of the first operation means to the second observed image which is obtained from the image input means when at least one of the lens position, the position of the image receiving plane, and the position of the image Input means Is moved; and a third operation means (2, 3) for obtaining the distance up to the object based on the results of the first operating means for the first observed Image, the result of the second operation means for the second observed image and the distance in which the said at least one of the lens, the image receiving plane and the image input means are moved.

Claim 7

Dependent Claim 45 words

The distance measuring apparatus according to Claim 4 wherein the said first and second operations (52, 63, 64) comprises an integration of the result obtained by multiplying the observed image input from the said image input means with a Gaussian function and a Fourier function.

Claim 8

Dependent Claim 85 words

The distance measuring apparatus according to Claim 5 wherein the said third operation obtains the distance a from the following expressions; (Fs′-Fs) (Δz)Fs = ks cos(ks)-sin(ks) sin(ks) s fΓ s= Γf a wherein Fs represents the result of the first operation, Fs′ represents the result of the second operation, Δz is the quantity of the movement, k is a predetermined frequency, Γ is the radius of the lens, f is the focus distance of the lens and a is the distance up to the object.

Claim 9

Dependent Claim 55 words

The distance measuring apparatus according to Claim 5 further comprising a memory means for storing a look-up-table TBL previously prepared for the result of the first operation, the result of the second operation and the distance up to the object and wherein the said third operation can be performed by referring to the said look-up-table.

Claim 10

Dependent Claim 44 words

The distance measuring apparatus according to Claim 7 wherein the said look-up-table (TBL) Is obtained by performing a calculation of the data associated with the result of the first operation and the result of the second operation obtained for the distance of the movement.

Claim 11

Dependent Claim 53 words

The distance measuring apparatus according to Claim 4 wherein the said image input means comprises a lens movement structure for moving the lens along the optical axis and outputs the first and second observed images obtained on the image receiving plane before the lens is moved and after the lens is moved, respectively.

Claim 12

Dependent Claim 59 words

The distance measuring apparatus according to Claim 4 wherein the said image input means comprises an image receiving plane structure for moving the image receiving plane along an optical axis and outputs the first and second observed Images on the image receiving plane before the image receiving plane is moved and after the image receiving plane is moved, respectively.

Claim 13

Dependent Claim 65 words

The distance measuring apparatus according to Claim 4 wherein the said image input means comprises a structure for moving the camera body along the optical axis keeping the positions of the lens and the Image receiving plane fixed and outputting the first and second observed images on the image receiving plane before the camera body is moved and after the camera body is moved, respectively.

Claim 14

Dependent Claim 44 words

The distance measuring apparatus according to Claim 4 wherein the said image input means is provided with a spectroscope and respective Image receiving plane with different distances from the spectroscope and output the first and second observed images at the respective image receiving plane.

Distance measuring method and apparatus

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