This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-156553, filed Jun. 3, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a distance measuring apparatus.
There are two kinds of distance measuring apparatus, that is an active mode distance measuring apparatus projecting distance measuring light onto an object and measuring distance by means of reflected signal light thereof, and a passive mode distance measuring apparatus using image patterns of an object. However, in the active mode there is a disadvantage of having a weakness to low-reflective or distant objects, and in the passive mode there is a disadvantage of not being capable of precisely measuring the distance in a dark scene where image patterns can not be obtained easily or the distance to soft and monotonous objects.
Therefore, in Jpn. Pat. Appln. KOKAI Publication No. 55-35399, Jpn. Pat. Appln. KOKAI Publication No. 7-167646 or the like, methods of measuring a distance corresponding to the surroundings of an object by using said two modes in combination are disclosed.
As described above, cameras being capable of bringing an object into focus precisely even in a scene hard to deal with only by one mode by changing an active mode over to a passive mode or vice versa have been conventionally proposed, and there are also examples of commercial production.
However, conventional distance measuring apparatus only combine two modes, or when the distance to an object can not be measured precisely by one mode, they only change one mode over to the other mode and measure the distance to said object. And it has not been discussed sufficiently to which part of the picture the distance should be measured.
Further, so-called multi-point distance measurable cameras being capable of measuring the distances to many points of a picture have increased in number, but such cameras take more time and show a higher probability of failed distance measurement as the distance measuring points increase in number.
Therefore, the object of the present invention is to provide a distance measuring apparatus being capable of bringing an object into focus fast and precisely.
In order to attain the object, according to the first aspect of the present invention, a multi-point distance measuring apparatus of a camera having a plurality of distance measuring points comprises:
a light source projecting distance measuring light onto an object;
a sensor array detecting an image pattern of each distance measuring point in the picture; and
a control circuit determining whether distance measuring light should be projected or not from the light source onto the each distance measuring point, based upon the output signals of the sensor array.
Further, according to the second aspect of the present invention, a multi-point distance measuring apparatus being capable of measuring distances to a plurality of points in the picture comprises:
a light source projecting light onto an object;
a first judging means judging whether the measurements of the distances to the plurality of points using the images of an object are possible or not;
a second judging means judging whether the measurements of the distances to the plurality of points involving light projection from the light source are possible or not; and
a control circuit making the distance measurement data of the points ineffective with respect to which distance measurement and light projection have been decided to be impossible by the first judging means and the second judging means respectively.
Further, according to the third aspect of the present invention, a multi-point distance measuring apparatus being capable of measuring distances to a plurality of blocks comprises:
a light source projecting light onto an object;
two line sensors receiving divided two images respectively in order to measure the distance to the object; and
a control circuit selectively changing over between passive distance measuring mode measuring distance based upon the image patterns outputted from the two line sensors and active distance measuring mode measuring distance, based upon the receiving position of reflected light from the object onto which light is projected by the light source on the line sensors,
wherein the control circuit changes over between the passive distance measuring mode and the active distance measuring mode per block, based upon the shape of the image patterns obtained by the line sensors.
Further, according to the fourth aspect of the present invention, a multi-point distance measuring apparatus of a camera comprises:
a sensor array detecting image data in the picture;
an integrating means integrating the output of the sensor array;
a deciding means deciding the relation of the image patterns obtained by the sensor array and the position of the image patterns in the picture;
a judging means judging a most suitable position for the main object among a plurality of predetermined points in the picture, based upon the change of image patterns corresponding to the plurality of points; and
a determining means determining the sensor area used for measuring distance according to the result of the judgment by the judging means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.