JPH066659A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To obtain the automatic focus device in which focusing is attained even when an object is in existence on both sides of the screen by performing focus control by means of a mount-climbing method where a focus lens is moved up to a position at which a focus evaluation is maximized. CONSTITUTION:A window pulse generating circuit 7 generates a window pulse used to limit focus areas A-C in integration circuits 8-10. The integration circuit 8 integrates a digital video signal in the focus area A, the integration circuit 9 integrates a digital video signal in the focus area B, and the integration circuit 10 integrates a digital video signal in the focus area C, and a focusing evaluation value of each of the focus areas A-C is outputted to a microcomputer 11 at every field. The microcomputer 11 moves a focus lens 1 at the focusing evaluation value in the focus areas A-C to drive the focus lens 1 so as to be in compliance with a peak value of the focus evaluation value to at first detect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus device for a video camera.

[0002]

2. Description of the Related Art Conventionally, as a camera autofocus system, a so-called hill-climbing system is well known in which the position of a focus lens is controlled so that the contrast of a screen is maximized by using a high frequency component of an image pickup signal. FIG. 24 is a block circuit diagram showing the configuration of a conventional autofocus device. In the figure, 1 is a focus lens, 2 is a solid-state image sensor, 3 is a signal processing circuit, 4 is a bandpass filter (hereinafter referred to as "BPF"), 5 is a detection circuit, and 6 is A.
/ D converter, 7 is a window generating circuit, 8 is an integrating circuit, 11 is a microcomputer, 12 is a motor driver, and 13 is a motor.

Next, the operation will be described. The optical image of the subject that has passed through the focus lens 1 is formed on the solid-state image sensor 2. The solid-state image sensor 2 converts an optical image into an electric signal. The electric signal output from the solid-state image sensor 2 is input to the signal processing circuit 3. The signal processing circuit 3 is the solid-state image sensor 2
The electric signal input from the is subjected to signal processing such as CDS and automatic gain control, and output as a video signal.

The bandpass filter 4 extracts a frequency band required for autofocus from the output signal of the signal processing circuit 3 and outputs it to the detection circuit 5. The detection circuit 5 detects the output signal of the bandpass filter 4, and the A / D converter 6
Output to. The A / D converter 6 converts the output signal of the detection circuit 5 into a digital signal. Window generation circuit 7
Defines a screen area (hereinafter referred to as “focus area”) used for autofocus in the above video signal,
Normally, a window pulse whose central area is the focus area is generated. The integration circuit 8 is the window generation circuit 7
Integrate the video signal in the focus area defined by
It is sent to the microcomputer 11 as a focus evaluation value serving as information for hill climbing control. The focus evaluation value exhibits a mountain-shaped characteristic as shown in FIG. 25 as the focus lens 1 moves. The microcomputer 11 drives the motor 13 via the motor driver 12 to move the focus lens 1. When the focus lens 1 moves to pass the mountain top and the focus evaluation value decreases, the microcomputer 11 reverses the moving direction of the focus lens 1,
The focus lens 1 is moved so that the subject in the focus area is focused so that the focus evaluation value is always maximized.

FIG. 26 shows a flowchart 6 of a conventional hill-climbing autofocus control means. Hereinafter, a description will be given according to the flowchart 6 shown in FIG. First, the focus lens 1 is moved to the front side (or the rear side) (step S30). Here, the focus lens position is "front" on the subject side and "rear" on the solid-state imaging device 2 side. It is determined whether or not the focus evaluation value has increased due to the movement of the focus lens 1 (step S31). If the focus evaluation value increases due to the movement of the focus lens, the focus lens is continuously moved until the focus evaluation value decreases, and it is determined whether the focus evaluation value is the peak of the mountain (step S3).
2). When the focus evaluation value is at the peak, it is determined that the focus is in focus, and the movement of the focus lens 1 is stopped.

If the focus evaluation value is lowered by the first movement of the focus lens 1 (step S30), the moving direction of the focus lens 1 is reversed and the focus lens 1 is moved backward (or forward) (step S30). S33).
By moving the focus lens 1 to the rear side,
It is determined whether or not the focus evaluation value has increased (step S3).
4). If the focus evaluation value increases due to the movement of the focus lens 1, the focus lens 1 is continuously moved until the focus evaluation value decreases, and it is determined whether the peak of the focus evaluation value is the peak (step S32). When the peak of the focus evaluation value is at the peak, it is determined that the focus is achieved, and the movement of the focus lens 1 is stopped.

[0007]

Since the conventional autofocus device is constructed as described above, the main subject is not focused unless it is within the focus area at the center of the screen. For example, when the main subject is on both sides of the focus area, the main subject is not focused.

If there is a wire mesh with high contrast in front of the person to be focused or there is wire mesh with high contrast behind the person, the focus evaluation first detected by moving the focus lens. Since the focus is on the peak of the value peak, there is a problem that which focus is to be set cannot be determined depending on the position of the focus lens.

Further, it is difficult to change the focusing condition depending on the subject.

Further, there is a problem that when a subject which is in focus due to the movement of the subject goes out of the focus area, a focusing operation is performed to search for a new object to be focused in the focus area.

Furthermore, once the subject is focused, it is difficult to change the subject to be focused with the video camera fixed. Therefore, if the focus lens is manually switched to change the subject to be focused manually, At the time of this operation, there was a problem that the camera shakes and a stable image cannot be obtained. .

The present invention has been made to solve the above problems, and an object thereof is to obtain an autofocus device capable of focusing even when there are subjects on both sides of the screen.

Another object of the present invention is to obtain an autofocus device capable of focusing on a subject to be focused.

Another object of the present invention is to obtain an autofocus device capable of focusing even when the subject moves.

Still another object of the present invention is to obtain an autofocus device capable of changing the subject to be focused in the focus area.

[0016]

According to a first aspect of the present invention, there is provided an autofocus device, which comprises a focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image pickup device as a focus evaluation value, and a focus evaluation value detecting means. A window generation circuit for setting an area and a focus control means by a hill climbing method for moving the focus lens to a position where the focus evaluation value is maximum are provided.

According to the second aspect of the present invention, the autofocus device detects the high-frequency component level of the video signal obtained from the image pickup element as the focus evaluation value, prioritizes a plurality of focus areas, and performs the focus. It is provided with a focus control means by a hill climbing method for moving the focus lens to a position where the evaluation value is maximum.

According to the third aspect of the present invention, the autofocus device detects the high-frequency component level of the video signal obtained from the image pickup element as the focus evaluation value, and the focus evaluation values of a plurality of focus areas are determined for each field. By comparison, the focus control means by the hill-climbing method for changing the priority of the focus area and moving the focus lens to the position where the focus evaluation value becomes maximum is provided.

According to another aspect of the present invention, there is provided an autofocus device which sets focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image pickup device as a focus evaluation value, and a plurality of focus areas. A window generating circuit, an external switch for changing the priority of the plurality of focus areas, and a focus control means by a hill climbing method for moving the focus lens to a position where the focus evaluation value becomes maximum. .

[0020]

In the autofocus device according to the first aspect of the present invention, the window generating circuit for setting the focus area is provided with a plurality of focus areas, and thus has a plurality of focus evaluation values for each focus area. Therefore, if there is a main subject in any of the focus areas, the subject is focused.

The autofocus device according to the second aspect of the present invention prioritizes the focus area for focusing.

In the autofocus device according to the third aspect of the present invention, the priority of the plurality of focus areas changes according to the change of the focus evaluation value for each field.

In the autofocus device according to the invention of claim 4, the priority of the focus area is changed by the external switch.

[0024]

EXAMPLES Example 1. FIG. 1 is a first embodiment of the invention of claim 1.
It is a block circuit diagram showing. Since 1 to 8 and 11 to 13 are similar to the conventional example, description thereof will be omitted. Reference numeral 9 is an integrating circuit, and 10 is an integrating circuit. The autofocus device configured as described above will be described below.

Until the A / D converter 6 outputs the digitally converted video signal to be used for autofocusing, it is the same as in the conventional example, and the description thereof is omitted. As shown in FIG. 2, the window generation circuit 7 generates window pulses that limit the focus areas (a), (b), and (c) to the integration circuits 8, 9, 10. The integrating circuit 8 integrates the digital video signal in the focus area (a). The integrating circuit 9 integrates the digital video signal in the focus area (b). The integrating circuit 10 has a focus area (C)
The digital video signal of is integrated. Each of the integrating circuits 8, 9 and 10 has its own focus area (a),
The focus evaluation values of (b) and (c) are output to the microcomputer 11 for each field.

FIG. 3 is a diagram showing the relationship between the position of the focus lens 1 when the subject shown in FIG. 2 is projected and the focus evaluation values output from the integrating circuits 8, 9 and 10. Figure 3
FIG. 3B shows the relationship between the focus lens 1 and the focus evaluation value of the focus area shown in FIG.
Shows the relationship between the focus lens 1 and the focus evaluation value of the focus area of (b) shown in FIG. 2, and FIG. 3 (c) shows the focus evaluation of the focus lens 1 and the focus area of (c) shown in FIG. Indicates the relationship with the value. When the subject shown in FIG. 2 is photographed, it is focused at the peak of the focus evaluation value shown in FIG.

FIG. 5 is a diagram showing the relationship between the position of the focus lens 1 when the subject shown in FIG. 4 is projected and the focus evaluation values output from the integrating circuits 8, 9 and 10. Figure 5
4A shows the relationship between the focus lens 1 and the focus evaluation value of the focus area of FIG. 4A, and FIG. 5B shows the focus evaluation value of the focus lens 1 and the area of FIG. 4B. FIG. 5C shows the relationship between the focus lens 1 and FIG.
The relationship between the focus evaluation value and the area (c) is shown. In this case, the focus is achieved at any of the peaks of the focus evaluation values shown in (a) and (b) of FIG.

As described above, the microcomputer 11 moves the focus lens 1 at the focus evaluation values of the focus areas (a), (b), and (c) to detect the peak focus evaluation value at the beginning. The focus lens 1 is moved so as to focus on.

Example 2. Next, a second embodiment of the invention of claim 2 will be described with reference to FIG. 1 and FIGS.

The circuit configuration of the second embodiment is similar to that of FIG.
Since the integration circuits 8, 9, and 10 input the focus evaluation values of the respective focus areas (a), (b), and (c) to the microcomputer 11, the description thereof is omitted because it is the same as that of the first embodiment.

FIG. 7 shows the position of the focus lens 1 and the focus output from the integrating circuits 8, 9 and 10 when a subject with a high frequency component such as a wire net is projected behind the main subject as shown in FIG. It is a figure showing a relation of an evaluation value. Figure 7 (a)
Shows the relationship between the focus lens 1 and the focus evaluation value of the focus area (a) in FIG. 6, and FIG. 7 (b) shows the focus evaluation value of the focus lens 1 and the focus area (b) in FIG. 7 (c) shows the relationship between the focus lens 1 and the focus evaluation value of the focus area (c) in FIG.

In the second embodiment, in a plurality of subjects at different distances from the video camera, the priority of the plurality of focus areas is determined by the distance from the subject. When the subject shown in FIG. 6 is being photographed, if the focus lens 1 is moved backward from the focus lens position a (front end) of FIG. 7, the result is correct in any of FIGS. 8A, 8B, and 8C. Although the focus evaluation value increases, the focus evaluation value of the focus area (b) decreases from the focus lens position b shown in FIG. Further, at the focus lens position c, the focus evaluation values of the respective focus areas (a), (b) and (c) have peaks. However, regarding the focus area (b), the focus lens position a and the focus lens position c
Has a peak value. From the above, it can be seen that there are objects in which the focus lens 1 is in focus at the focus lens position a and objects in which the focus lens 1 is in focus at the focus lens position c, which have different distances from the video camera to the object. The autofocus control means of the second embodiment will be described below.

8 and 9 are flowcharts showing the autofocus control means of the second embodiment. FIG. 8 is a flowchart 1 in the case of focusing on the subject closest to the video camera, and FIG. 9 is an example of the flowchart 2 in the case of focusing on the subject farthest from the video camera.

First, the case of focusing on a subject located at the shortest distance from the video camera will be described with reference to the flow chart 1 in FIG. The microcomputer 11 first moves the focus lens 1 to the front end position (step S1). Next, the focus lens 1 is moved to the rear side, and the integrating circuit 8,
Focus areas (a), (b), (c) from 9 and 10
The focus evaluation value of is input (step S2). The microcomputer 11 has respective focus areas (a),
It is determined whether or not the focus evaluation values of (b) and (c) have increased by moving the focus lens 1 backward (step S3). If the focus evaluation values of all the focus areas increase with the movement of the focus lens 1, the focus lens 1 is continuously moved backward.

By moving the focus lens 1 to the rear side, the focus areas (a), (b), (c)
When any one of the focus evaluation values of (1) is lowered, the focus area where the focus evaluation value is first lowered is given priority (step S4). The autofocus focuses on the subject within the focus area that has been prioritized (step S5).
When the subject shown in FIG. 6 is photographed, the focus area (b) is given priority, and the focus lens position b in FIG.
Focus on.

Next, the case of focusing on a subject at the farthest distance from the video camera will be described with reference to the flowchart 2 of FIG. The microcomputer 11 first moves the focus lens 1 to the front end position (step S6). Next, the focus lens 1 is moved to the rear side (step S7), and the focus evaluation values of the focus areas (a), (b), and (c) are obtained from the integrating circuits 8, 9, and 10 for each field or every several fields. input. The microcomputer 11 determines whether or not the focus evaluation values of the respective focus areas (a), (b) and (c) have increased by moving the focus lens 1 backward (step S8). If the focus evaluation values of all the focus areas increase with the movement of the focus lens 1, the focus lens 1 is continuously moved.

By moving the focus lens 1 to the rear side, the focus areas (a), (b), (c)
When any one of the focus evaluation values of 1 has decreased, it is determined whether or not the focus evaluation values of the focus areas other than the focus areas for which the focus evaluation value has decreased increase with the movement of the focus lens 1 (step S9). ). If the focus evaluation value of any of the focus areas is lowered, the focus lens 1 is focused at the position where the focus evaluation value is lowered (step S12). When the focus evaluation values of other focus areas continue to increase, the focus lens 1 is further moved backward (steps S10 and S11), and the focus area where the focus evaluation values continue to increase until the end is given priority ( Step S13). Autofocus focuses on the subject within the focused focus area (step S
14). When the subject shown in FIG. 6 is photographed, the focus areas (a) and (b) are prioritized, and the object is focused at the focus lens position c in FIG.

In the second embodiment, the microcomputer 11 first moves the focus lens 1 to the front end and then to the rear side. However, after moving the focus lens 1 to the rear end first, the focus lens 1 is moved to the front side. It can also be realized. However,
It goes without saying that the auto-focus control means follows the flowchart shown in FIG. 9 when focusing on the object closest to the video camera and follows the flowchart shown in FIG. 8 when focusing on the object farthest from the video camera.

Further, in the second embodiment, an example of the flowchart in which the focus area is prioritized when the distance from the video camera is the farthest and the distance is the closest is shown. For example, the focus in which the second peak is detected is shown. The priority of the focus area such as focusing on the lens position is not limited to the above distance.

Example 3. Next, another embodiment 3 of the invention of claim 2 will be described with reference to FIGS. 1 and 10 to 13.

The circuit configuration of the third embodiment is similar to that of FIG.
Since the integration circuits 8, 9, and 10 input the focus evaluation values of the respective focus areas (a), (b), and (c) to the microcomputer 11, the description thereof is omitted because it is the same as that of the first embodiment.

FIG. 11 shows the position of the focus lens 1 and the focus evaluation output from the integrating circuits 8, 9 and 10 when a subject with many high frequency components such as a wire net is projected behind the main subject as shown in FIG. It is the figure which showed the relationship of a value. Figure 11
FIG. 11B shows the relationship between the focus lens 1 and the focus evaluation value of the focus area A in FIG.
Shows the relationship between the focus lens 1 and the focus evaluation value of the focus area (C) in FIG. 10, and FIG. 11C shows the relationship between the focus lens 1 and the focus evaluation value of the focus area of FIG. 10C. Show the relationship.

In the third embodiment, the priority of a plurality of focus areas is determined by the area ratio of the object in the image frame being photographed. When the focus lens 1 is moved from the focus lens position a (front end) shown in FIG. 11 to the rear side when the subject shown in FIG. 10 is photographed, the focus areas (a), (b) and (c) shown in FIG. Although the focus evaluation values are both increased, the focus evaluation values of the focus areas (b) and (c) are decreased from the focus lens position b shown in FIG. Further, at the focus lens position c, the focus evaluation values of all the focus areas (a), (b) and (c) have peaks. Therefore, the peak of the focus evaluation value exists in the two focus areas (b) and (c) at the focus lens position a, and the focus area (b) at the focus lens position b.
There are three focus areas, (b) and (c). From the above, it can be seen that, among the subjects being photographed, there are subjects that extend from the focus area (b) to (c) and subjects that extend across the entire focus areas (a), (b), and (c). The autofocus control means of the second embodiment will be described below.

12 and 13 are flowcharts showing the autofocus control means of the second embodiment. Figure 1
2 is a flow chart 3 for focusing on a subject having a small area ratio among the subjects in the focus area, and FIG. 13 is an example of a flow chart 4 for focusing on a subject having a large area ratio among the subjects in the focus area. Is.

First, a case of focusing on a subject having a small area ratio among the subjects within the focus area will be described with reference to the flowchart 3 of FIG. The microcomputer 11 first moves the focus lens 1 to the front end position (step S15). Next, the focus lens 1 is moved to the rear side to move from the integrating circuits 8, 9, 10 to the focus area (a) for each field or every several fields.
The focus evaluation values of (b) and (c) are input (step S1).
6).

Further, the microcomputer 11 moves the focus lens 1 to the rear side, detects the focus lens position of the peak of each focus evaluation value, and the focus area where the focus evaluation value has the peak at that focus lens position. The number is detected (step S17). It is determined whether or not the focus evaluation values of all the focus areas have decreased by moving the focus lens 1 backward (step S18). When the focus evaluation values of all the focus areas have decreased, the microcomputer 11 reverses the moving direction of the focus lens 1, and the focus lens position at which the focus evaluation value reaches a peak has a small number of detected focus areas. The focus lens 1 is moved toward the lens position (step S19). Figure 1
When the subject 0 is photographed, the microcomputer 11 moves the focus lens 1 to the focus lens position b to focus on the person shown in FIG.

Next, a case of focusing on a subject having a large area ratio among the subjects within the focus area will be described with reference to the flowchart 4 of FIG. The microcomputer 11 first moves the focus lens 1 to the front end position (step S20). Next, the focus lens 1 is moved backward (step S21), and focus evaluation values of focus areas (a), (b), and (c) are input from the integrating circuits 8, 9, and 10 for each field or every several fields. To do.

Further, the microcomputer 11 moves the focus lens 1 to the rear side, detects the focus lens position of the peak of each focus evaluation value, and the focus area where the focus evaluation value has the peak at the focus lens position. The number is detected (step S22). It is determined whether or not the focus evaluation values of all the focus areas have decreased by moving the focus lens 1 backward (step S23). When the focus evaluation values of all the focus areas have decreased, the microcomputer 11 reverses the moving direction of the focus lens 1, and at the focus lens position where the focus evaluation value has a peak, the focus having the large number of detected focus areas is detected. The focus lens 1 is moved toward the lens position (step S24). Figure 10
When the subject shown in FIG. 2 is being photographed, the microcomputer 11 sets the focus lens 1 to the focus lens position c.
Then, the wire mesh shown in FIG. 10 is focused.

Example 4. Next, a fourth embodiment of the invention of claim 3 will be described with reference to FIGS. 1 and 14 to 20.

The circuit configuration of the fourth embodiment is similar to that of FIG.
Since the integration circuits 8, 9, and 10 input the focus evaluation values of the respective focus areas (a), (b), and (c) to the microcomputer 11, the description thereof is omitted because it is the same as that of the first embodiment.

FIG. 17 shows the position of the focus lens 1 and FIG.
6 is a diagram showing the relationship between the focus evaluation values of the focus areas (a), (b), and (c) of the subject in FIG. FIG. 18 shows the position of the focus lens 1 and FIG.
Each focus area (a) of the subject in
It is a figure which showed the relationship with (b) and (c) focusing evaluation value.
FIG. 19 shows the position of the focus lens 1 and the focus areas (a), (b) of the subject in FIG.
(C) It is a figure showing the relationship with a focus evaluation value. FIG. 17-
19 (a), (b), and (c) are shown in FIG.
4 to 16 focus areas (a), (b),
It corresponds to (C).

The microcomputer 11 has an integrating circuit 8,
Focus areas (a) from 9 and 10,
The process is the same as that of the first embodiment until the focus evaluation values of (b) and (c) are input for each field or every several fields, and therefore the description is omitted.

FIG. 20 is a flow chart 5 showing the autofocus control means of the fourth embodiment. Hereinafter, a description will be given according to the flowchart 5 in FIG. First, the microcomputer 11 performs a focusing operation according to the flowchart 1 shown in FIG. 8 (step S25). Since the flowchart 1 shown in FIG. 8 is the same as that of the first embodiment, its explanation is omitted.
Once the subject is focused, the microcomputer 11 uses the focus evaluation values of the focus areas (a), (b), and (c) input from the integration circuits 8, 9, and 10 and the focus evaluation values of the previous fields. Are compared to determine whether they are large or small (step S26). And microcomputer 1
1 indicates that if the focus evaluation value of the focused focus area is smaller than the focus evaluation value of the previous field, another focus area having a larger focus evaluation value than the previous field is given priority (step S28). ). The microcomputer 11 moves the focus lens 1 so as to focus on the subject in the focused focus area (step S29). After focusing on the subject in the focused focus area, steps S26 to S29 are repeated.

The focus evaluation value of the focused focus area is smaller than the focus evaluation value of the previous field, and the focus evaluation values of the other focus areas are the focus evaluation values of the previous field. When it is not larger than the value, the microcomputer 11 moves the focus lens 1 so as to focus on the subject in the focus area which was initially focused.

For example, when the subject shown in FIG. 14 is projected, autofocus focuses on the person shown in FIG. 14 at the position of the focus lens position a shown in FIG. Next, FIGS.
As shown in Fig. 6, when the main subject moves to the left,
As shown in FIGS. 7 to 19, the focus evaluation value of the focus area a decreases as the subject moves, and the focus evaluation value of the focus area b increases as the subject moves.
According to the flowchart 5 of FIG. 20, from the state of focusing at the position a of the focus lens shown in FIG.
The focus evaluation values of focus areas (a), (b) and (c) are compared with the focus evaluation values of the previous field. When the focus evaluation value of the focus area (b) becomes smaller than the focus evaluation value of the previous field due to the movement of the main subject, the microcomputer 11 determines that the focus evaluation value of the same focus area of the previous field. The focus area (a) that is larger than the focus evaluation value is given priority, and the focus area (a)
The focus lens 1 is moved so as to focus on the subject inside, and the focus is focused at the position of the focus lens position b.

Example 5. 21 to 23 are views showing a fifth embodiment of the invention of claim 4. FIG. 21 is a block circuit diagram showing the circuit configuration of the fifth embodiment. Since 1 to 13 are the same as those in the first embodiment, the description thereof will be omitted. Reference numeral 14 is an external switch for selecting a subject to be focused. The autofocus device configured as described above will be described below.

Since the operation of auto-focusing until the subject is focused is the same as that of the second embodiment, its explanation is omitted. When the subject shown in FIG. 22 is projected, the focus evaluation value of each focus area is as shown in FIG. FIG. 23
22B is a diagram showing the relationship between the focus lens 1 and the focus evaluation value of the focus area (A) shown in FIG. 22. FIG.
FIG. 23B is a diagram showing the relationship between the focus lens 1 and the focus evaluation value of the focus area (B) shown in FIG. FIG. 23C is a diagram showing the relationship between the focus lens 1 and the focus evaluation value of the focus area (C) shown in FIG.

As described in the second embodiment, it is now assumed that the auto-focus device is designed to focus on the objects at the shortest distance from the video camera with respect to some objects within the photographing area. Focusing is performed at the position of the focus lens position a in b). External switch 14
Outputs the input signal A or the input signal B to the microcomputer 11 by pressing the right or left of the external switch 14. When the input signal A is input to the microcomputer 11, the focus lens 1 is again moved to the arrow D shown in FIG.
After the hill climbing operation is started in the direction of, the focus is focused at the peak of the focused subject detected by the microcomputer 11 next. Therefore, when the input signal A is input to the microcomputer 11 while focusing at the focus lens position a, the focus lens 1 moves rearward and is focused at the focus lens position b. Input signal A again
When is input to the microcomputer 11, it is focused at the position of the focus lens position c similarly to the above. Further, when the input signal B is input to the microcomputer 11, FIG.
A mountain climbing operation is started in the direction of arrow E shown in. In this way, the subject to be focused can be switched by the A and B signals from the external switch 33.

[0059]

As described above, according to the invention of claim 1,
Focusing is possible not only when there is a subject in the center of the shooting region but also when there are subjects on both sides of the shooting region.

Further, according to the second aspect of the present invention, even if there are a plurality of subjects within the photographing area, the focus position does not change depending on the subjects, and the subject to be focused is always focused. Is possible.

According to the third aspect of the present invention, it is possible to focus on the main subject even if the main subject moves within the photographing area.

Further, according to the invention of claim 4, even after the focusing operation is once ended, the subject to be focused is changed with respect to a plurality of subjects within the photographing region so that the photographer can focus. It is possible to focus on the desired subject.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration of an autofocus device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a focus area in a shooting area and a first subject according to the first exemplary embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a focus lens position of a first subject and a focus evaluation value.

FIG. 4 is a diagram illustrating a focus area in a shooting area and a second subject according to the first exemplary embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a focus lens position of a second subject and a focus evaluation value.

FIG. 6 is a diagram showing a focus area in a photographing area and a third subject according to the second embodiment of the invention of claim 2;

FIG. 7 is a characteristic diagram showing a relationship between a focus lens position of a third subject and a focus evaluation value.

FIG. 8 is a diagram showing a flowchart 1 of control of the autofocus device according to the second embodiment.

FIG. 9 is a diagram showing a flowchart 2 of the second embodiment.

FIG. 10 is a diagram showing a focus area in a photographing area and a fourth subject according to the third embodiment of the present invention.

FIG. 11 is a characteristic diagram showing a relationship between a focus lens position of a fourth subject and a focus evaluation value.

FIG. 12 is a diagram showing a flowchart 3 of the third embodiment.

FIG. 13 is a diagram showing a flowchart 4 of control according to the third embodiment.

FIG. 14 is a diagram showing a focus area in a photographing area and a fifth subject according to a fourth embodiment of the invention of claim 3;

FIG. 15 is a diagram showing a focus area in a photographing area and a fifth subject according to the fourth embodiment of the invention of claim 3;

FIG. 16 is a diagram showing a focus area in a photographing area and a fifth object in the fourth embodiment of the present invention.

17 is a characteristic diagram showing a focus lens position and a focus evaluation value in FIG.

18 is a characteristic diagram showing the focus lens position and the focus evaluation value in FIG.

19 is a characteristic diagram showing the focus lens position and the focus evaluation value in FIG.

FIG. 20 is a diagram showing a flowchart 5 of control of the autofocus device according to the fourth embodiment of the present invention.

FIG. 21 is a block circuit diagram showing a configuration of an autofocus device according to a fifth embodiment of the present invention.

FIG. 22 is a diagram illustrating a focus area in a shooting area and a sixth subject according to the fifth embodiment.

FIG. 23 is a characteristic diagram showing a relationship between a focus lens position of a sixth subject and a focus evaluation value.

FIG. 24 is a block circuit diagram showing a configuration of a conventional autofocus device.

FIG. 25 is a characteristic diagram showing a relationship between a focus lens position and a focus evaluation value in so-called hill climbing control of a conventional example.

FIG. 26 is a view showing a flowchart 6 of control of the conventional autofocus device.

[Explanation of symbols]

 1 Focus Lens 2 Solid-State Image Sensor 3 Signal Processing Circuit 4 Band Pass Filter 5 Detection Circuit 6 A / D Converter 7 Window Generation Circuit 8 Integrating Circuit 9 Integrating Circuit 10 Integrating Circuit 11 Microcomputer 12 Motor Driver 13 Motor 14 External Switch

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[Procedure amendment]

[Submission date] August 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

According to a first aspect of the present invention, there is provided an autofocus device, which comprises a focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image pickup device as a focus evaluation value, and a focus evaluation value detecting means. A window generation circuit for setting a plurality of areas and a focus control means by a hill climbing method for moving the focus lens to a position where the focus evaluation value is maximum are provided.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

[Figure 10]

Claims (4)

[Claims] 1. A focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image pickup device as a focus evaluation value, a window generating circuit for setting a plurality of focus areas, and the focus evaluation value. An autofocus device including a focus control unit that uses a hill climbing method to move the focus lens to a position where the maximum. 2. A focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image pickup device as a focus evaluation value, a window generating circuit for setting a plurality of focus areas, and the plurality of focus areas. And a focus control means by a hill climbing method for moving the focus lens to a position where the focus evaluation value is maximized. 3. A focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image sensor as a focus evaluation value, a window generating circuit for setting a plurality of focus areas, and the plurality of focus areas. The focus evaluation means of the hill-climbing method that compares the focus evaluation value of each field for each field and moves the focus lens to a position where the focus evaluation value is maximized by changing the priority of a plurality of focus areas apparatus. 4. A focus evaluation value detecting means for detecting a high frequency component level of a video signal obtained from an image sensor as a focus evaluation value, a window generating circuit for setting a plurality of focus areas, and the plurality of the plurality of window generating circuits. A mountain climbing method that moves the focus lens to the position where the focus evaluation value becomes maximum by changing the priority of the external switch that switches the focus area to be focused among the focus areas and the multiple focus areas selected by this external switch. An autofocus device including a focus control unit according to.