JP3489280B2 - Imaging device and focus display method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus such as a video tape recorder (hereinafter referred to as "camcorder") integrated with a camera, and more particularly to a focus display during manual focus control.

[0002]

2. Description of the Related Art Manual focus control in an image pickup apparatus such as a camcorder is performed by a user operating an operation member for manual focus such as a focus ring or a lever while observing an image of a subject displayed on a viewfinder. It was common to adjust the position of the manual focus operation member so that the subject would not be out of focus.

However, in such a manual focus control method, it is necessary to move the focus lens in a direction opposite to the in-focus position or to move the in-focus position too far and then return it. There was a problem that it took a lot of time. Further, it is difficult to perform accurate focusing with a viewfinder having a low resolution.

Therefore, in order to solve such a problem, at the time of manual focus control, a focus state is judged based on a focus signal for autofocus control and the focus state is displayed on a viewfinder or the like, so that it can be quickly and easily performed. There has been proposed an image pickup apparatus capable of focusing on.

This image pickup device detects a focus signal from a high frequency component of a video signal obtained by picking up an image of a subject, determines a focus state from the focus signal, and displays a predetermined pattern on a viewfinder or the like accordingly. To do.

FIG. 4 shows an example of the relationship between the focus signal level and the focus position in this image pickup apparatus. in this way,
The focus signal has a peak at the in-focus position. Also, FIG.
Shows the relationship between the focus signal tilt and the focus position. When the tilt is positive, the front focus (the focus is in front of the subject), when the tilt is negative, the back focus is (the focus is behind the subject), and the tilt is 0 at the focus position. Becomes

Therefore, the focus lens is slightly moved,
The focus direction (front focus, rear focus) can be known by detecting the change (inclination) of the focus signal. Further, when the level of the focus signal is above a certain level and the inclination of the focus signal is small (below the focus determination level), it can be regarded as the focus. Then, the result of this focus determination is displayed on the viewfinder.

FIG. 6 shows an example of focus display. The user can know the in-focus position by moving the focus ring etc. according to the display direction of the front focus and the rear focus, and the focus position can be known, so move the focus lens in the direction opposite to the focus position, or the focus position. It is not necessary to perform an operation such as returning after overshooting, and as a result, focusing can be performed quickly and easily. Also, even with a low-resolution viewfinder,
High-precision focusing can be performed.

[0009]

It is premised that the above-mentioned image pickup apparatus detects the inclination of the focus signal, and that the level of the focus signal increases as it approaches the in-focus position and decreases as it moves away. However, in practice, the focus signal may fluctuate due to the influence of noise of the focus signal, camera shake of the image pickup apparatus, and the like, so that there are such problems as described in (1) to (3) below.

(1) Display change when the focus ring is stationary When the focus ring is stationary, the focus state should not change originally, but when the focus signal level greatly changes due to camera shake, the focus state changes. It will be judged that there is. As a result, the focus display changes, which makes it difficult for the user to determine the focus state.

(2) The display focus display which is inconsistent with the operation direction of the focus ring indicates in which direction the focus lens should be moved to bring the subject into focus. For example, in the front focus state, the focus state should be obtained by moving the focus lens in the infinite direction, and when the focus lens is further moved in the infinite direction, the focus state should be in the rear focus state.

However, when the level of the focus signal greatly changes due to camera shake or the like, focus determination and focus state display different from the actual focus state may be performed. For example, even if you move the focus lens from the focus position to infinity, it will be displayed as a front focus,
The focus may be displayed even if the focus lens is moved further in the infinite direction from the rear pin display state. In such a case, it is difficult to adjust the focus according to the focus indication.

(3) Limitation on Focus Determination Accuracy Although the focus determination accuracy can be set high by reducing the focus determination level shown in FIG. 5, on the other hand, the display becomes unstable. , I could not set the accuracy too high.

The present invention has been made in view of the above problems, and provides an image pickup apparatus and a focus display method thereof that can easily perform focusing only by following the focus display even if camera shake or the like occurs. The purpose is to

It is another object of the present invention to provide an image pickup apparatus and a focus display method thereof, which can perform stable focus display even if the precision of focus determination is set high.

[0016]

In order to solve the above-mentioned problems, an image pickup apparatus according to the present invention creates a focus signal from a predetermined frequency component of an output signal of an image pickup element to make a focus determination, and as a result, An image pickup apparatus for displaying the focus is provided with means for detecting motion information of the manual focus operation member and means for performing focus display in accordance with the motion information, and the means for performing focus display is the manual focus operation. When it is detected that the member is stationary, the change of the focus display is prohibited. Further, in the image pickup apparatus according to the present invention, the focus signal is generated from a predetermined frequency component of the output signal of the image pickup element to perform the focus determination, and the result of focusing is displayed in the image pickup apparatus. A means for detecting information and a means for performing focus display in accordance with the motion information are provided, and the means for performing focus display prohibits transition of focus display contrary to the moving direction of the manual focus operation member. It is a feature.

In order to solve the above-mentioned problems, a focus display method of an image pickup apparatus performs a focus determination based on a focus signal generated from a predetermined frequency component of an output signal of an image pickup element,
A focus display method of an image pickup apparatus for displaying the result in focus, wherein motion information of a manual focus operation member is detected, focus display is performed in accordance with the motion information, and the manual focus operation member is stationary. When this is detected, the change in focus display is prohibited. Further, the focus display method of the image pickup device is a focus display method of the image pickup device for performing focus determination based on a focus signal created from a predetermined frequency component of the output signal of the image pickup device and displaying the result in focus. It is characterized in that the movement information of the manual focus operation member is detected, the focus display is performed in accordance with the movement information, and the transition of the focus display contrary to the moving direction of the manual focus operation member is prohibited.

[0018]

According to the image pickup apparatus of the present invention, the movement information of the focus ring or the like is detected, and the focus display is performed according to the movement information. For example, changing the focus state when the focus ring is stationary, and changing the focus display in a direction opposite to the focus display transition direction theoretically derived from the moving direction of the focus ring are prohibited.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an image pickup apparatus to which the present invention is applied. An image pickup apparatus to which the present invention is applied includes a focus lens 1 that collects light from a subject (not shown), an iris 2 that adjusts the amount of light that has passed through the focus lens 1, and a subject that has passed through the iris 2. CCD image sensor 3 for converting an image into a video signal, and CCD
A sample / hold and AGC circuit 4 for removing noise and level adjustment of an output video signal of the image sensor 3, an A / D converter 5 for digitizing the output of the sample / hold and AGC circuit 4, and an A / D converter And a camera signal processing unit 6 for performing signal processing such as Y / C separation and gamma correction on the digital output of No. 5.

Further, in the image pickup apparatus to which the present invention is applied, the focus signal for autofocus control is generated from the luminance signal separated in the camera signal processing unit 6 and is sent to the control microcomputer 8 which will be described later. A control microcomputer 8 that controls autofocus and manual focus control operations (details will be described later), a motor drive circuit 9 that drives a motor 10 in response to a motor control signal sent from the control microcomputer 8, and a motor drive circuit. The motor 10 is driven by 9 to move the focus lens 1.

As shown in FIG. 2, the auto-focus detection section 7 includes a high-pass filter (or band-pass filter) 71 that passes the high-frequency component of the luminance signal, and this filter 71.
Rectifying circuit 72 for rectifying the output of the rectifying circuit, a gate circuit 73 for extracting a luminance signal in the ranging frame for autofocus from the output of the rectifying circuit 72, and detecting the output of the gate circuit 73 The detection circuit 74 detects a high frequency component and creates a focus signal.
As the detection circuit 74, an average value detection, a peak value detection, an intermediate detection method between the both are used.

Further, the image pickup apparatus to which the present invention is applied includes a focus ring rotation detector 11 which detects rotation of a focus ring (not shown) during manual focus control and sends it to the control microcomputer 8, and a control microcomputer during manual focus control. And a focus display section 12 that performs focus display according to a focus state display control signal sent from the camera 8.

Next, the operation of the image pickup apparatus shown in FIG. 1 will be described. In FIG. 1, light from a subject (not shown) is condensed by the focus lens 1, adjusted to an appropriate light amount by the iris 2 and imaged on the CCD image pickup device 3.
Then, it is converted into a video signal here, subjected to noise removal and level adjustment in the sample / hold and AGC circuit 4, and then converted into a digital signal by the A / D converter 5. The video signal converted into a digital signal is subjected to camera signal processing such as Y / C separation and gamma correction in the camera signal processing unit 6. The output signal of the camera signal processing unit 6 is sent to a recording / reproducing circuit (not shown) and subjected to predetermined recording / reproducing processing. The luminance signal separated in the camera signal processing unit 6 is sent to the autofocus detection unit 7.

The autofocus detector 7 creates a focus signal from the input luminance signal and sends it to the control microcomputer 8.
The control microcomputer 8 performs different operations during auto focus control and manual focus control.

At the time of autofocus control, the control microcomputer 8 gives a control signal for moving the focus lens 1 to the motor drive circuit 9 in a direction in which the level of the focus signal increases. The motor drive circuit 9 rotates the motor 10 in the direction and speed according to the control signal. As a result, the position of the focus lens 1 is automatically controlled so that the focus signal level reaches its peak.

In the manual focus control, when the user rotates the focus ring for focusing, the focus ring rotation detector 11 detects the rotation of the focus ring, and the control microcomputer 8 sends a motor control signal corresponding to the rotation state. It is given to the motor drive circuit 9.
At this time, the control microcomputer 8 uses the autofocus detection unit 7
The focus state is determined based on the focus signal from and the display control signal is sent to the focus display unit 12. The focus display unit 12 displays the focus, front focus, or rear focus as shown in FIG. 6 according to the display control signal. The user can keep the position of the focus lens 1 within the in-focus range by rotating the focus ring while looking at the display content on the focus display section 12.

FIG. 3 is a flow chart showing an example of the operation of the control microcomputer during the manual focus control. As shown in this figure, the control microcomputer first takes in the rotation signal of the focus ring sent from the focus ring rotation detection unit 11 of FIG. 1 (step S1). Then, it is determined whether or not the focus ring is stationary (step S2), and if it is stationary, the focus display is not changed (step S3). When it is determined in step S2 that the focus ring is not stationary, the rotation direction of the focus ring is determined in the next step S4.

In this embodiment, it is determined whether or not the focus lens is rotating so as to move in the infinite direction. Then, when rotating so as to move in infinite direction, theoretically it should change in the order of front pin → focus → rear pin, so rear pin → focus and focus → front pin display The transition is prohibited (step S5). On the other hand, when it is not rotated so as to move in the infinite direction in step S4, theoretically it should change in the order of rear focus → focus → front focus, so front focus → focus The display transition of focus → back pin is prohibited (step S6).

Here, the steps S1 to S6 form a loop which is repeated at the cycle of the vertical synchronizing signal of the video signal obtained by image pickup.

[0030]

As described in detail above, according to the present invention, since the movement information of the focus ring or the like is referred to and the focus display is performed in accordance with the movement information, the following effects (1) to (3) are obtained. .

(1) The user can easily determine the focus state even if camera shake or the like occurs. (2) Even if camera shake occurs, focusing can be easily performed simply by following the focus display.

(3) Since the focus display is stable even if camera shake or the like occurs, the focus determination level can be reduced,
As a result, the accuracy of the focus determination can be increased.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image pickup apparatus to which the present invention has been applied.

FIG. 2 is a block diagram showing a configuration of an autofocus detection unit in FIG.

FIG. 3 is a flowchart showing an example of the operation of the control microcomputer during manual focus control in the image pickup apparatus to which the present invention is applied.

FIG. 4 is a diagram showing an example of a relationship between a focus signal level and a focus position.

FIG. 5 is a diagram showing an example of a relationship between a focus signal inclination and a focus position.

FIG. 6 is a diagram showing an example of focus display.

[Explanation of symbols]

1 ... Focus lens, 7 ... Auto-focus detection unit,
8 ... Control microcomputer, 10 ... Motor, 11 ... Focus ring rotation detection unit, 12 ... Focus display unit

Claims (4)

(57) [Claims] 1. A means for detecting movement information of a manual focus operation member in an image pickup apparatus for producing a focus signal from a predetermined frequency component of an output signal of an image pickup element, performing focus determination, and displaying the result in focus. And means for performing focus display in accordance with the movement information, and the means for performing focus display prohibits change in focus display when it is detected that the manual focus operation member is stationary. An imaging device characterized by: 2. A means for detecting movement information of a manual focus operating member in an image pickup apparatus for producing a focus signal from a predetermined frequency component of an output signal of an image pickup element, performing focus determination, and displaying the result in focus. And a means for performing focus display in accordance with the motion information, wherein the means for performing focus display prohibits transition of focus display contrary to the moving direction of the manual focus operation member. . 3. A focus display method for an image pickup apparatus, wherein focus determination is performed based on a focus signal created from a predetermined frequency component of an output signal of an image pickup device, and the result is displayed in focus, which is a manual focus operation member. Motion information of
A focus display method for an image pickup apparatus, which performs focus display in accordance with the movement information, and prohibits a change in focus display when it is detected that the manual focus operation member is stationary. 4. A focus display method for an image pickup apparatus, wherein focus determination is performed based on a focus signal generated from a predetermined frequency component of an output signal of an image pickup element, and the result is displayed in focus, which is a manual focus operation member. Motion information of
A focus display method for an image pickup apparatus, comprising: performing focus display in accordance with the motion information, and prohibiting transition of focus display contrary to a moving direction of the manual focus operation member.