Photography – With exposure objective focusing means – focusing aid – or... – With amplification control
Reexamination Certificate
2002-12-06
2004-03-23
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
With amplification control
C396S121000
Reexamination Certificate
active
06711350
ABSTRACT:
This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No.
2001-373187
filed Japan on Dec. 6, 2001, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distance measuring apparatus, and particularly to a distance measuring apparatus of, for example, a camera, using passive AF sensors.
2. Description of the Related Art
The distance measurement using passive AF sensors is known as a process of imaging a distance measurement object by, for example, a pair of left and right line sensors and calculating the distance of the distance measurement object from the amount of deviation between left and right sensor images obtained by the left and right line sensors. In the passive method, the possibility that the distance of the distance measurement object is erroneously measured is generally high because it is difficult to detect the amount of deviation between the left and right sensor images by calculation of correlation values or the like if the contrast of the sensor image (of distance measurement object) is low. Furthermore, in this specification, data indicating the luminance of each pixel of the sensor image obtained by line sensors is referred to as sensor data, and the sensor data itself for use in calculation of correlation values and the like for calculating the distance of the distance measurement object, or data with the sensor data subjected to special processing (contrast extraction processing, etc.) is referred to as AF data.
Also, a distance measurement method is known in which the sensor area of a pair of left and right line sensors is divided into a plurality of areas (herein referred to as divided areas), and sensor images (AF data) are compared between the corresponding divided areas of the left and right line sensors, whereby the distance of the distance measurement object is calculated for each divided area. In this way, even if distance measurement objects of different distances exist in the distance measurement area, their distances can be individually detected, and therefore it advantageously possible to select an appropriate distance measurement object and bring the object into focus. Furthermore, in the case where distance measurement objects of different distances have been detected, typically, the nearest distance measurement object is brought into focus.
Sensor data or AF data is generated by, for example, integrating for each cell the signals outputted from each cell of the line sensor, but conventionally, the output signals of each cell are integrated simultaneously for the same period of time in the entire area of the line sensor (or within the distance measurement area of the distance measurement object) to obtain the sensor data (AF data) in the gross even if the distance of the distance measurement object is to be calculated for each divided area. Usually, the period of integration is adjusted according to the luminance of the distance measurement object so that a proper contrast can be obtained, but if the sensor data is obtained in the gross, there are cases where problems occur such that making the contrast proper in some portions makes the contrast improper in other portions, and thus the distance of the distance measurement object can be calculated only in part of divided areas. In particular, if there exists a more luminous distance measurement object (e.g., the sun) that is not a main distance measurement object, there are cases where the contrast of the more luminous distance measurement object is given priority to compromise the contrast the main distance measurement object, and consequently the distance of the main distance measurement object is not calculated even though the distance of the distance measurement object is calculated for each divided area.
SUMMARY OF THE INVENTION
The present invention has been devised in view of these situations, and its object is to provide a distance measuring apparatus enabling proper sensor data (AF data) to be obtained for each divided area for individually calculating the distance of the distance measurement object, thereby reliably performing the distance measurement of a main distance measurement object in the distance measurement using passive AF sensors, and also reducing the distance measurement time and so on.
For achieving the above-described object, the present invention is directed to a distance measuring apparatus, comprising: a sensor data generating device which forms images of light from a distance measurement object on a pair of line sensors constituted by a plurality of light receiving elements, integrates signals obtained from the light receiving elements for each light receiving element to generate a pair of sensor data, and ends the integration when sensor data of selected areas set as the distance measurement area of the each line sensor satisfies predetermined integration end conditions; a sensor data acquiring device which divides the distance measurement area of the each line sensor into a plurality of divided areas, and acquires the sensor data of each divided area from the sensor data generating device; a distance measurement object distance calculating device which individually calculates the distances of the distance measurement object for each divided area according to the sensor data acquired by the sensor data acquiring device; and a distance measurement object distance determining device which determines the distance of the distance measurement object to be employed in focusing control according to the distances of the distance measurement object for each divided area calculated by the distance measurement object distance calculating device, wherein the sensor data acquiring device sets a plurality of the selected areas each constituted by one or more the divided areas in the distance measurement area, causes the sensor data generating device to start the integration for each selected area and performs in succession processing for acquiring the sensor data of the selected area from the sensor data generating device when the integration is ended, and performs processing for dividing and acquiring sensor data to acquire sensor data of each divided area.
According to the present invention, the distance measurement area is divided into a plurality of selected areas, and sensor data is acquired for each selected area, thus making it possible to acquire proper sensor data at every time while the sensor data acquired for each selected area is not influenced by distance measurement objects in other selected areas. For example, even if there exists a distance measurement object of high luminance that is not a main distance measurement object (distance measurement object of which distance is to be measured), the sensor data for the main distance measurement object can be acquired with a proper value (contrast) without being influenced by the distance measurement object of high luminance, and the distance of the main distance measurement object can be measured suitable and reliably.
Preferably, the sensor data acquiring device selectively performs, depending on the luminance of the distance measurement object in the distance measurement area, one of: the processing for dividing and acquiring sensor data; and processing for acquiring sensor data in gross to sets the entire area of the distance measurement area as the selected area to acquire the sensor data of each divided area in the distance measurement area in gross from the sensor data generating device.
According to the present invention, the following advantage is provided. In the case where the distance measurement area is divided into a plurality of selected areas and sensor data is acquired for each selected area, more suitable and reliable distance measurement can be carried out compared to the case where sensor data is acquired in the gross in the distance measurement area, but there is a disadvantage that extra distance measurement time is required for acquiring sensor data for each selected area (note
Mihara Yoshikazu
Yoshida Hideo
Fuji Photo Optical Co., Ltd.
Perkey W. B.
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