EP0163394A2
Expired / Lapsed
EP
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An automatic focussing device
Assignee: Cambio Ragione Sociale applied Imaging Internation
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Filing: 1985-04-09
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Granted: —
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Expires: 2005-04-09
Abstract
Abstract An automatic focussing arrangement, incorporated in a system in which an optical image is focussed onto a plane, comprises a sensor assembly comprises at least two arrays of sensor devices, one array of sensor devices being in front of the plane, and the second array of sensor devices being behind the plane. Means are provided for moving the image relative to the sensor assembly or for moving the sensor assembly relative to the image. From the first and second arrays signals are derived representative of the image received by the said sensor devices. A focus drive signal to maintain the focus of the arrangement as desired is derived from the signals.
Inventors
- 👤 Geoffrey Shippey
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 07:22
CPC Classifications
G; G02; G02B; G02B21/00; G02B21/24; G02B21/241; G02B21/244
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
127 words
I. An automatic focussing arrangement, incorporated in a system in which an optical image is focussed onto a focus plane, comprising a sensor assembly located in the region of the focus plane to sense the image, the sensor assembly comprising at least two arrays of sensor devices, one array of sensor devices being in front of the focus plane, and the second array of sensor devices being behind the focus plane, means being provided for effecting relative movement between the image and to the sensor assembly, means being provided for deriving from the first and second arrays signals representative of the image received by the said sensor devices, and for deriving, from those signals, a focus drive signal to maintain the focus of the arrangement as desired.
Claim 2
Dependent Claim
25 words
An arrangement according to claim I, wherein a further sensor arrangement is provided, which is located in a focus plane, to sense the focussed image.
Claim 3
Dependent Claim
52 words
An arrangement according to claim I or claim 2, wherein the arrays of sensor devices are all mounted on a single substrate which is tilted relative to said plane, the first and second arrays being located in regions of the substrate that are in front of and behind said focus plane respectively.
Claim 4
Dependent Claim
27 words
An arrangement according to claim 3, wherein the arrays all form part of a single "chip" of arrays, each array comprising an array of charge coupled devices.
Claim 5
Dependent Claim
43 words
An arrangement according to any one of the preceding claims, wherein the arrays are elongate arrays and the relative movement between the sensor assembly and said image in said focus plane is in a direction transverse to the longitudinal axes of said arrays.
Claim 6
Dependent Claim
75 words
An arrangement according to claim 5, wherein the arrangement further comprises means for deriving a signal representative of the contrast of part of the image as viewed by one of the first and second array, means for storing the information at least until such time that the other of said arrays respectively senses the same part of the image, and means for comparing the information from the said arrays to derive said focus drive signal.
Claim 7
Dependent Claim
69 words
An arrangement according to any one of the preceding claims, wherein the first and second sensor arrays each consist of a plurality of sensing elements adapted to provide output signals representative of the levels of light intensity received by adjacent or next adjacent sensing elements, said deriving means including means to calculate the difference between signals from said first and second arrays to provide a signal representative of contrast.
Claim 8
Dependent Claim
43 words
An arrangement according to claim 7, wherein all calculated differences less than a predetermined value are deemed to be zero, and all remaining differences have said predetermined value subtracted therefrom, the contrast representing signal being calculated as a function of the remaining value.
Claim 9
Dependent Claim
37 words
An arrangement according to any one of claims I to 8, wherein an analog output signal from each of the first and second arrays is passed through an analog to digital converter to create a digital signal.
Claim 10
Dependent Claim
22 words
An arrangement according to claim 9, wherein each digital signal is subjected to a logarithmic conversion process prior to said subtraction process.
Claim 11
Dependent Claim
70 words
An arrangement according to any one of claims 1 to 10, wherein each of the first and second sensor arrays comprises two staggered rows of light sensitive devices, signals from one of the rows of the said first array being processed and signals from the other of the rows of the second array being processed, thus enabling the same processing circuitry to be utilised for the first and second arrays.
References Cited (Backward Citations)
No citation records indexed.
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