Photography – With exposure objective focusing means – focusing aid – or... – Reliability of focus/distance signal
Reexamination Certificate
2003-08-11
2004-07-13
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Reliability of focus/distance signal
C396S125000, C348S345000
Reexamination Certificate
active
06763187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera apparatus with an auto focusing function, which includes a plurality of auto focusing devices and which is capable of carrying out a high speed and a high accuracy focusing by using an optimum auto focusing device corresponding to a photographing mode.
2. Description of the Prior Art
Conventionally, a camera apparatus such as a still camera or a video camera or the like is provided with an auto focusing (hereinafter, referred to as AF) function for adjusting a focusing of an image of a subject automatically. A contrast type AF function (hereinafter, referred to as contrast AF) is often used in an electronic camera device such as a digital camera.
The contrast AF moves a focus lens of a camera and evaluates with sampling a contrast (including a sharpness of the image) of the image of the subject obtained by a CCD or the like in every movement of the focus lens of the camera through the focus lens sequentially at real time, and stops the movement of the focus lens by judging that a position in which an evaluated value becomes maximum is a focusing position.
The contrast AF requires a long time to focus, but, has an advantage that a focusing accuracy is high.
The evaluated value is generally created by an output of a high frequency transmission filter of a CCD output signal or the like, and it takes more time to focus as a number of sampling increases. For example, the number of sampling increases as a focusing distance of a photographic optical system becomes longer, a range of a photographing distance becomes wider or setting a frequency of the sampling higher to raise the focusing accuracy, thereby a time required for the focusing also becomes longer.
Also, a ranging type AF function (so-called an outside light AF) is often used for a silver salt camera or the like. The outside light AF carries out a distance measuring to the subject by projecting an infrared ray or a supersonic wave or the like to the subject and moves the focus lens to the focusing position corresponding to the measured distance.
Although a focusing accuracy of the camera inferiors to the focusing accuracy compared with the contrast type AF, the ranging type AF function has an advantage that a focusing speed is high and is adapted to photograph a dynamic subject.
As described above, those AF functions each have a different advantage. In this connection, Japanese Patent Laid Open No. 2001-255456 describes an AF device which has both of two kinds of AF functions and which is capable of switching so as to select either AF function selectively corresponding to a photographing condition or a condition of the subject.
According to the Japanese Patent Laid Open No. 2001-256456, it is constituted that the contrast type AF function can be used when carrying out the photographing which the focusing accuracy is required, and the outside light AF function can be used when carrying out the photographing with a mode (dynamic subject mode, continuous photographing mode) corresponding to “scene that a time-lag is undesirable” such as photographing the dynamic subject or photographing the subject that is moving fast continuously.
However, in the AF device disclosed in the Japanese Patent Laid Open No. 2001-255456, a photographer has to select either of the two kind of AF functions beforehand. Therefore, there is a case of losing a timing for the photographing when the contrast type AF function which takes long time to focus while the focusing accuracy is high is previously selected and suddenly a necessity of photographing the “scene that the time-lag is undesirable” such as photographing the subject that moving fast is occurred.
In recent, there has been proposed an AF device that either of AF functions is automatically selected by an operation of a shutter release button. According to such AF device, the contrast type AF function is selected, if the shutter release button is half-pressed and then is pressed slowly, and the outside light AF function is selected if the shutter release button is pressed at once without being half-pressed. The contrast type AF function can be used when carrying out the photographing that the high focusing accuracy is required such as a portrait photograph or the like by pressing-in the shutter release button slowly, and the outside light AF function can be used when carrying out the photographing that the timing for the photographing is necessary such as photographing the dynamic subject as the subject by pressing-in the shutter release button at once.
However, depending on the photographing condition, there is a case that the focusing accuracy is desired to prioritize rather than a focusing time regardless of the operation of the shutter release button.
For example, a self-timer photographing carries out the photographing after a certain waiting time is lapsed after pressing the shutter release button, accordingly, there is no necessity of considering the timing for the photographing. The high focusing speed is not required since there is the waiting time for the photographing to be started after the shutter release button is pressed, and therefore it is appropriate to carry out the photographing by prioritizing the focusing accuracy.
In such case, there has been a problem in the above AF device that the enough focusing accuracy cannot be obtained since the outside light AF which the focusing time is prioritized is to be selected if the photographer presses-in the shutter release button at once.
On the contrary, even when it is appropriate that the focusing time prioritizes rather than the focusing accuracy, there has been also a problem of losing the timing for the photographing since the contrast type AF unction is selected depending on the photographer's operation so it takes time to be focused.
SUMMARY OF THE INVENTION
The present invention has been made in view of the aforementioned circumstances and it is, therefore, an object of the present invention to provide a camera apparatus with an auto focusing function for preventing a failure of photographing by selecting an AF function that is suitable for a photographing condition automatically even though an operation selecting the AF function that not suitable for the photographic condition is carried out in a photographing mode corresponding to the photographing condition.
To accomplish the aforementioned object, according to a camera apparatus with an auto focusing function in the first aspect of the present invention, it comprises a ranging type auto focusing device for carrying out a focusing by measuring a distance to a subject and moving a focus lens to a focusing position corresponding to the measured distance; a contrast type auto focusing device for carrying out the focusing by moving the focus lens while evaluating a contrast of an image of the subject obtained through the focus lens and judging a focusing position based on tho evaluated contrast together with stopping the focus lens at the judged focusing position.
The apparatus is capable of selecting either the ranging type auto focusing device or the contrast type auto focusing device to carry out the focusing based on a command for an operation of a photographer.
The apparatus has also a photographing mode to carry out the focusing by the contrast type auto focusing device even when the command for the operation to select the focusing by the ranging type auto focusing device is carried out by the photographer.
According to a camera apparatus with an auto focusing function in the second aspect of the present invention, it comprises a ranging type auto focusing device for carrying out a focusing by measuring a distance to a subject and moving a focus lens to a focusing position corresponding to the measured distance; a contrast type auto focusing device for carrying out the focusing by moving the focus lens while evaluating a contrast of an image of the subject obtained through the focus lens and judging a focusing position based on the evaluated contrast together with stoppin
Perkey W. B.
Ricoh & Company, Ltd.
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