JP2002277726A - Automatic focusing device and camera equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic focusing device which can be surely focused even on a consecutively moving subject in a short time, and a camera equipped with the automatic focusing device. SOLUTION: This automatic focusing device for automatically adjusting a focus by dividing a scanning range to two areas, that is, a 1st area and a 2nd area and moving a lens is equipped with a selection means 46 selecting either the 1st area or the 2nd area as the moving area of the lens. When a still picture is taken ordinarily, the focus is adjusted by moving the lens in the area selected by the selection means. In a specified operation mode, the focus is adjusted by moving the lens in all the areas including the 1st area and the 2nd area regardless of the selection of the selection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the operation of an automatic focusing device (AF).

[0002]

2. Description of the Related Art An ordinary camera is equipped with an automatic focus adjustment device (AF) so that the focus is automatically adjusted according to the movement of a subject. However, if the lens movement becomes longer, it takes time (for example, up to 2
Seconds) and miss a photo opportunity. Therefore, usually, a mode for photographing a subject farther than, for example, 60 cm (hereinafter, referred to as a “normal mode”)
Is set with However, in the normal mode, a close-up mode (hereinafter, referred to as a “macro mode”) is prepared because the focus becomes out of focus when an attempt is made to photograph a nearby subject (for example, a subject located at a position of 10 cm). In normal shooting, when shooting in normal mode, and when shooting close-ups, shooting in macro mode moves the lens within that range, shortening the time required for focus adjustment, and There is no risk of missing a chance.

A camera has been reported that can reduce the time required for an autofocus operation and can perform appropriate photographing (Japanese Patent Laid-Open No. 2000-147368). In this camera, when either the macro mode for close-up shooting or the normal mode for normal distance shooting is selected, if the focus cannot be adjusted in the selected mode,
The focus lens is scanned by moving the focus lens in the movement range corresponding to another shooting mode, and the focus position is detected. If the detected focus position is not in the range corresponding to the selected shooting mode, shooting is performed. Change mode. In this case, when there are two modes, a normal mode and a macro mode, a scan is performed with priority given to a preset area (hereinafter, referred to as a “set area”). Therefore, it takes time to scan an area other than the setting area. This example will be described with reference to FIG. In FIG. 5, consider the case where the current setting is the macro mode. Then, the lens is positioned at the point A in FIG. 5 (●).
It is assumed that Here, when point B is the position of the subject, ideally, focusing can be performed by scanning in the direction of arrow (3). However, conventionally, first, scanning is performed in the direction of the arrow (1) in the macro area. And the close distance (1
Scanning is performed up to 0 cm), and when a peak value cannot be detected, scanning is performed in the direction of arrow (2) to reach point B. In this method, since the scanning is performed beyond the region, the focal position can be adjusted, but it takes time to move in the direction of arrow (1) and in the direction of arrow (2). . Therefore, in this conventional technique, when there is a peak outside the set area, the scan takes time.

[0004]

As described above, in an automatic focus adjustment device (AF) that selectively divides a distance measurement range into two, although the distance measurement time can be shortened, it extends over two regions. There is a problem that a moving subject becomes out of focus.

If the focusing area is divided into two and there is no focus position in the selected area, the non-selection area is also scanned to find the focus position, and the focus position is found in the non-selection area. For example, there is a method of using a non-selected area as a selected area, but there is a problem that it takes time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic focus adjusting device capable of quickly and reliably focusing even on a continuously moving subject, and a camera provided with the automatic focus adjusting device. I do.

[0007]

According to the present invention, the following means have been taken in order to solve the above-mentioned problems.

An automatic focus adjustment apparatus according to the present invention divides a scan range into two areas, a first area and a second area, and automatically adjusts focus by moving a lens. And selecting means for selecting any one of the first area and the second area as a moving area of the lens, wherein the area selected by the selecting means at the time of capturing a normal still image The lens moves inside to adjust the focus, and in a predetermined operation mode, the lens moves and focuses on the entire area including the first area and the second area regardless of the selection of the selecting means. The adjustment is performed. In this automatic focus adjustment device,
It is preferable that the predetermined operation is any one of a full-time AF operation, a moving image AF operation, and a through image display operation.

Further, a camera according to the present invention is provided with the above-mentioned automatic focus adjusting device.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an electronic camera according to the present invention. In FIG. 1, an optical image of a subject that has passed through a lens group 11 including a zoom lens 11a, an aperture 11b, and a focus lens 11c is converted into an electric signal by a CCD 12, and is converted into an analog image signal by an imaging circuit 13. The analog image signal is converted into a digital image signal (hereinafter, also referred to as “image information”) by the A / D converter 14 and is temporarily stored in the volatile built-in memory 25. The built-in memory 25 has a high speed, for example, an SDRAM (Synchronous Dy).
natural Random Access Memor
y), and is also used as a work area for image processing described later.

The image processing circuit 21 performs processing such as conversion of color information of image information temporarily stored in the built-in memory 25 and conversion of the number of pixels. The image information that has been subjected to various image processes in the image processing circuit 21 is, for example, JPEG-compressed by the compression / expansion unit 22 and recorded in the removable memory 20 such as a smart media.

When displaying a photographed image, the image information after the image processing is transmitted to the LCD driver 31 via the LCD driver 31.
The image is displayed on the image display LCD 30.

When displaying an image recorded in the detachable memory 20, the image information read from the detachable memory 20 is decompressed by the compression / decompression unit 22. For example, predetermined image processing is performed by the image processing circuit 21. After that, the image is displayed on the image display LCD 30 in the same manner as in the shooting.

The main CPU 40 reads a basic control program of the electronic camera from a nonvolatile memory 41 such as a flash memory and controls the entire electronic camera.

The sub CPU 45 receives an input from an operation unit 46 (including a release button, a cross key, and the like, not shown) and performs control according to the input. Also, sub C
The PU 45 controls a power supply unit (not shown) to manage the power supply of the entire electronic camera. Further, the sub CPU 45
The drive of the lens group 11 is controlled via a lens drive circuit 15.

The sub CPU 45 further controls a driving circuit 47 such as a lens to drive the zoom lens 11a, the aperture 11b, and the focus lens 11c, respectively.
Specifically, the zoom lens 11a enlarges a subject by a zoom lever (not shown). The aperture 11b adjusts the F value by changing the size of the opening in accordance with the output from an AE circuit (not shown) or the setting with the cross key. The focus lens 11c moves in the direction of the arrow to adjust the focus. Here, as described above, since it takes time for the focus lens to move the entire moving distance, the moving distance of the focus lens is divided into two, and the shooting mode is assigned to each area, and the time required for the focus adjustment is reduced. Shortened. FIG. 2 is a flowchart showing the flow of the operation of the focus lens 11c according to the shooting mode. When the shooting mode is set, it is determined whether the mode is the normal mode or the macro mode (step A1). If the mode is the macro mode in step A1, the mode is shifted to the macro mode (step A2), and the focus lens is moved to the macro initial position (step A).
3). Then, AF is performed in the macro area (step A).
4). If the mode is the normal mode in step A1, the mode is shifted to the normal mode (step A2), and the focus lens is moved to the normal area initial position (step A3). Then, AF is performed in the normal area (step A4). FIG. 3 is a flowchart showing the flow of the AF operation according to the present invention. According to FIG. 3, first, in performing the AF operation, it is determined whether or not the operation mode is a mode such as moving image shooting (step B1). When the operation mode is the still image shooting, the target to be shot is determined, so that the focusing operation is performed in the selected area of the normal area or the macro area (step B2). In step B1, when photographing a moving image or the like, if an attempt is made to execute the AF operation in the selected area,
As described above, there is a possibility that focusing takes a long time. In this case, control is performed so that the AF operation is performed in all the regions regardless of the selected region (step B).
3).

In FIG. 3, the mode for capturing a moving image or the like is a mode for basically capturing or displaying a continuous image (however, does not include reproduction of a moving image from a recording medium). Refers to a mode in which the AF operation is continuously performed. Specifically, a full-time AF operation, a moving image AF
This refers to either an operation or a through image display operation. In this specification, the “through image display operation” refers to an operation of displaying a subject image captured by the CCD 12 on an image display LCD (liquid crystal monitor) in real time.

The algorithm for executing the AF operation in step B3 in FIG. 3 will be described with reference to FIG. FIG. 4 is a diagram for explaining the algorithm. In FIG. 4, for example, the subject is (1) → (2)
Consider the case of moving in the order of → (3) → (4). Here, the movement from (3) to (4) is such that the area spans from the normal area to the macro area. In this case, as long as the subject does not suddenly change its traveling direction, the distance between the subject and the camera can be predicted. Therefore, in the present invention, the movement from (3) to (4) is (1) → By predicting the distance between the camera and the subject in (4) based on the movement result of (2) → (3) (or only (2) → (3)),
Focusing is performed in the direction (4) beyond the setting area without scanning the entire area in the normal mode area which is the setting area. As described above, it is effective to predict the position by predicting the next operation from one or two or more operations before the current time of the subject, but the present invention is also applicable when such prediction is not performed. It is valid. For example, in FIG. 4, when the subject moves from the vicinity of the boundary value, it is assumed that the subject is present at the current position (3), for example, as described above. In FIG. 4, it is assumed that the position (3) is in the normal mode area but is adjacent to the macro area. At this time, it is assumed that the subject has moved to the position (4). In this case, in the related art, first, since the position of the subject is determined in the normal mode, the operation is performed such that the macro area is scanned after the scan is performed so that the position of the subject is in the direction of ∞. Therefore, a time for scanning in the normal mode and a time for scanning in the macro mode are required. On the other hand, in the present invention, the data on both sides of the position (3) (for example,
Since the position of the subject (4) is obtained from the range (a or both sides thereof in the figure), without performing unnecessary scanning,
Focusing can be done in a short time. Therefore, according to the present invention, accurate focusing can be performed in a short time even when focusing is performed beyond the set area. The present invention is not limited to the above embodiment of the present invention. For example, in the above embodiment, an example in which the present invention is applied to an electronic camera has been described.
It is applicable to all cameras with F function.
The present invention can be applied to other optical devices as the F device. In addition, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0019]

As described above, according to the present invention, it is possible to prevent the focus from being out of focus even when the AF operation is continuously performed when the macro mode is set at the time of photographing.

In a mode in which the AF operation is continuously performed, such as a full-time AF operation, a moving image AF operation, and a through image display operation, basically, A
There is little requirement for high-speed F, but rather continuous followability of AF is required for a moving subject, so that focusing by gradual lens movement is sufficient. Therefore, in such an operation mode, even if the entire area is scanned, there is no problem in the operation, and even when the subject moves out of the set first or second area, the focus adjustment can be performed. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic camera.

FIG. 2 is a flowchart illustrating control of a focus lens in a shooting mode.

FIG. 3 is a flowchart showing a flow of an AF operation based on an operation mode.

FIG. 4 is a diagram for explaining an algorithm of an AF operation according to the present invention.

FIG. 5 is a diagram showing a conventional scanning method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Lens group 11a ... Zoom lens 11b ... Aperture 11c ... Focus lens 12 ... CCD 13 ... Imaging circuit 14 ... A / D converter 15 ... Lens etc. drive circuit 20 ... Removable memory 21 ... Image processing circuit 22 ... Compression / expansion unit 25 ... Built-in memory 30 ... LCD for image display 31 ... LCD driver 40 ... Main CPU 41 ... Non-volatile memory 45 ... Sub CPU 46 ... Operation unit 47 ... Drive circuit for lens etc.

Claims (3)

[Claims] 1. An automatic focus adjustment device that divides a scan range into two areas, a first area and a second area, and automatically adjusts a focus by moving a lens. The first region and the second region
A selection unit for selecting any one of the regions, during normal still image shooting, the lens moves within the region selected by the selection unit to perform focus adjustment, and in a predetermined operation mode, An automatic focus adjustment device, wherein the focus is adjusted by moving the lens over an entire area including the first area and the second area regardless of the selection of the selection unit. 2. The automatic focusing apparatus according to claim 1, wherein the predetermined operation is a full-time AF operation, a moving image AF operation,
An automatic focus adjustment device, which is one of an operation and a through image display operation. 3. A camera comprising the automatic focus adjustment device according to claim 1.