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US 4,304,474 AGranted
Arrangement for focusing the image of an object onto an image plane
AssigneeSiemens Aktiengesellschaft
InventorKarl-Ulrich Stein
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AssigneeSiemens Aktiengesellschaft
InventorKarl-Ulrich Stein
Estimating the term…
The invention relates to an arrangement for automatically focusing the image of an object, obtained by an objective lens system, onto an image plane by adjustment of the distance of the objective lens system or a portion thereof from such image plane. Two optical devices which are mutually offset transversely to the optical axis, are provided for obtaining auxiliary images of the object, which are photoelectrically analyzed with respect to one another. The minimum difference signal therebetween indicates the congruency of the two auxiliary images and supplies an adjustment criterion for a device operative to correspondingly adjust the objective distance. The invention utilizes two CTD image sensors to analyze the auxiliary images with the read-out signals being supplied to a differential amplifier and subsequently rectified and integrated. The read-out signals of one sensor are modified, as to their phase state with respect to the output signals of the other sensor, by adjusting movement of the relevant optical device, or by means of a delay element, which can be adjusted in step-like fashion. The phase state associated with the minimal difference signal represents the setting criterion. The invention can be utilized in photographic cameras and the like and, in particular, those with additional range and flash or speed facilities.
In an arrangement for focusing the image of an object onto an image plane, wherein the image is derived over an objective lens system which can be adjusted, with respect to its distance from the image plane, by means of a setting device, and in which two optical devices are provided which are offset from one another transversely to the optical axis and supply two auxiliary images of the object, with a device being provided which analyzes the auxiliary images, in the form of electrical signals, and serves to control the setting device, the combination of the analyzing device containing two CTD image sensors which are individually assigned to the auxiliary images, and whose aligned image points are arranged parallel to one another and in the direction of mutual displacement of the auxiliary images, an evaluating circuit, having one input to which the output of one CTD image sensor is operatively connected, and a second input to which the output of the other image sensor is connected over a delay element which can be adjusted, in a stepped manner, in a setting sequence, for forming from the difference between a sequence of read-out signals from the two image sensors assigned to the setting sequence, a sequence of read-out signals integrated over said image points, and means in said evaluating circuit for forming an adjusting signal in correspondence to such read-out signals, which is characteristic of the delay set on the occurrence of the integrated read-out signal having the smallest amplitude, and which causes the objective distance to be set to a value assigned to such delay.
In an arrangement for focusing the image of an object onto an image plane, wherein the image is derived over an objective lens system which can be adjusted, with respect to its distance from the image plane, by means of a setting device, and in which two optical devices are provided which are offset from one another transversely to the optical axis and supply two auxiliary images of the object, with a device being provided which analyzes the axiliary images, in the form of electrical signals, and serves to control the setting device, the combination of the analyzing device containing two CTD image sensors which are individually assigned to the auxiliary images, and whose aligned image points are arranged parallel to one another and in direction of mutual displacement of the auxiliary images, the output of one CTD image sensor being connected to a first delay line having a plurality of mutually offset outputs, a series of differential amplifiers respectively having first inputs to which said outputs of said first delay line are connected, and respectively having second inputs operatively connected in common to the output of the other CTD image sensor, an evaluating circuit having respective inputs, each of the outputs of said amplifiers being connected to a corresponding one of said inputs of said evaluating circuit by a rectifier and a serially connected integrator, said evaluating circuit having means for determining the integrator having the smallest output signal and means for producing an adjusting signal which is characteristic of said smallest output signal and causes a setting to an objective distance assigned thereto.
Dependencies are inferred from the claim text.