JPH0851563A - Image pickup device - Google Patents

Abstract

PURPOSE:To eliminate a fog from being generated by providing a 1st lens group for focus adjustment and a 2nd lens group placed on its optical axis to revise the focal distance and a magnification of the device and moving the 1st lens group with the revision of the mount state of the 2nd lens group thereby restarting all focusing control. CONSTITUTION:An AF microcomputer 115 receives an evaluation value signal from an AF evaluation value processing circuit 117 while vibrating a focus compensation lens 105 very small by wobbling operation to discriminate whether or not an image is fogged. When the image is fogged, the operation of a hill climbing method in the direction of discrimination result is conducted and when a peak of an evaluation value signal is not exceeded, the operation of a hill climbing method continues. When exceeded, the operation is conducted while being restored to the lens 105, and when the peak is reached, whether or not the point reaches the focus is discriminated to conduct wobbling to restart the focusing control. When the mount of the wide attachment lens 122 is changed, the position of the lens 15 is changed to obtain a new focus.

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, and more particularly to automatic focusing control in an image pickup apparatus equipped with a wide attachment lens.

[0002]

2. Description of the Related Art FIG. 4 is a schematic configuration diagram of an inner focus type lens system equipped with a wide attachment lens unit. In FIG. 4, 101 is a fixed first fixed lens group, 102 is a variable magnification lens group for changing the magnification, 103 is a diaphragm, 104 is a fixed second fixed lens group, and 105 is a focus adjustment function and a change function. A lens group (hereinafter referred to as a focus competition lens) that also has a so-called competition function that corrects the movement of the focal plane due to double magnification, 1
Reference numeral 06 is an image sensor (CCD).

Reference numeral 122 denotes a wide attachment lens which is detachable on the same optical axis as the inner focus type lens system, and when this lens is attached, the focal length of the lens system is changed,
The magnification rate changes. As is well known, in the lens system configured as shown in FIG.
Has both a focus adjustment function and a competition function, the position of the focus competition lens 105 for focusing on the imaging surface (image sensor) 106 varies depending on the subject distance even if the focal lengths are the same.

When the subject distance is changed at each focal length when the wide attachment lens 122 is not attached, the position of the focus compensating lens 105 for focusing on the image sensor 106 is continuously plotted. It becomes as shown. Therefore, during the zooming operation, by selecting the locus shown in FIG. 5 according to the subject distance and moving the focus compensating lens 105 according to the selected locus, zooming without blurring is possible.

On the other hand, the wide attachment lens 122
When mounted, the locus shown in FIG. 5 changes as shown in FIG. That is, when the wide attachment lens 122 is attached, the loci corresponding to the respective object distances are all shifted to the close side and the shape of the locus is changed, as compared with when the wide attachment lens 122 is not attached.

Therefore, the wide attachment lens 12
In order to perform zooming without blurring during zooming with the No. 2 mounted, it is necessary to perform zooming control different from that when the wide attachment lens 122 is not mounted. As shown in FIG. 6, on the telephoto side of the focal length 602, the locus diverges outside the focusable area in accordance with the subject distance, so that focusing becomes impossible. For this reason, when the wide attachment lens 122 is attached, it is common to fix the variable power lens group 102 at the wide end position and prohibit the zoom operation.

As a conventional automatic focusing (AF) control method, generally, a high frequency component of a video signal obtained from an image pickup device 106 such as a CCD is extracted, and the high frequency component is A
A so-called hill-climbing method is adopted in which the focus evaluation lens is driven to perform focus adjustment so that the AF evaluation value signal becomes maximum.

[0008]

However, as is apparent from the above description, the wide attachment lens 122 is or is not attached (that is, the attachment state is changed) even when the subject at a certain distance is in focus. As a result, the position of the focus compensating lens 105 for focusing on a subject at the same distance changes, causing blurring.

However, conventionally, A in the blurred state
The F evaluation value signal is fetched, and it is determined whether or not the focus control is restarted based on the AF evaluation value signal, that is, whether or not the focus compensating lens 105 is again moved and controlled, and the focus is corrected. Therefore, it took a long time to reach the focus.

Further, the wide attachment lens 122
Even if the focus direction is judged during AF operation, such as when the camera is greatly out of focus due to wearing, the AF evaluation value signal cannot be sufficiently changed and the blur stops or the focus direction is incorrect. There was also a problem that the decision made increased blurring, and the time to focus was delayed.

The present invention has been made under such a background, and its purpose occurs when the mounting state of the wide attachment lens (lens for changing the focal length and the magnification) is changed. It is to eliminate the blur quickly.

[0012]

In order to achieve the above object, the invention according to claim 1 is a first aspect for performing focus adjustment.
Lens group (corresponding to focus competition lens 105)
And a second lens group capable of freely changing the mounted state of mounted / not mounted on the same optical axis as the first lens group, and changing the focal length and the magnification ratio by changing the mounted state. (Corresponding to the wide attachment lens 122), and the position of the first lens group focused on a specific subject distance is changed by changing the mounting state of the second lens group. A lens system and a sharpness signal corresponding to a focus degree is extracted from a video signal obtained by photoelectrically converting an optical subject image formed via the lens system, and the first lens is extracted based on the sharpness signal. Focus control means (AF) for performing focus control by moving the group
An evaluation value processing circuit 117, an AF microcomputer 115, a driver 120, and a motor 121), and when the mounting state of the second lens group is changed,
A restart means (AF microcomputer 11) for moving the first lens group to restart the focus control by the focus control means.
(Corresponding to 5).

In order to achieve the above object, in the invention according to claim 2, the restarting means in claim 1 has a detecting means for detecting a change in a mounting state of the second lens group, and the detecting means When the change of the mounting state of the second lens group is detected by the means, the first lens group is moved and the focusing control by the focusing control means is restarted.

In order to achieve the above-mentioned object, in the invention according to claim 3, the restarting means in claim 1 is such that when the mounting state of the second lens group is changed, the restarting means is predetermined according to the changed state. The first lens group is moved in the direction to restart the focusing control by the focusing control means.

In order to achieve the above-mentioned object, in the invention according to claim 4, the restarting means in claim 3 moves in the close-up direction when the second lens group is changed from the mounted state to the non-mounted state. When the non-wearing state is changed to the wearing state, the first lens group is moved in the infinite direction and the focusing control by the focusing control means is restarted.

[0016]

According to the first aspect of the present invention, the focus control means extracts a sharpness signal corresponding to the focus degree from a video signal obtained by photoelectrically converting an optical object image formed through the lens system. Then, focusing control is performed by controlling movement of the first lens group based on the sharpness signal, and the restarting unit is configured to change the mounting state of the second lens group when the mounting state of the second lens group is changed. By moving the first lens group and restarting the focusing control by the focusing control means,
The blur that occurs when the mounting state of the lens group is changed is quickly eliminated.

According to a second aspect of the present invention, the restarting means in the first aspect has a detecting means for detecting a change in the mounting state of the second lens group, and the second lens is detected by the detecting means. When a change in the mounting state of the group is detected, the first lens group is moved to restart the focusing control by the focusing control means, whereby the mounting state of the second lens group is changed. Quickly eliminates the blurring that occurs when

According to a third aspect of the present invention, the restarting means according to the first aspect, when the mounting state of the second lens group is changed, the first lens is moved in a predetermined direction according to the changed state. By moving the group and reactivating the focusing control by the focusing control means, the blurring that occurs when the mounting state of the second lens group is changed can be eliminated more swiftly and reliably.

In a fourth aspect of the present invention, the restarting means in the third aspect is in the close-up direction when the second lens group is changed from the mounted state to the non-mounted state, and from the non-mounted state to the mounted state. If changed to the first direction in the infinite direction
By moving the second lens group and restarting the focusing control by the focusing control means, blurring occurring when the mounting state of the second lens group is changed can be eliminated more swiftly and reliably. .

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram of a video integrated camera to which an image pickup apparatus according to an embodiment of the present invention is applied.

In FIG. 1, 101 to 105 are components of the inner focus type lens system described with reference to FIG. 4, 101 is a fixed first fixed lens group, and 102 is a variable magnification changing lens. Double lens group, 103
Is a diaphragm, 104 is a fixed second fixed lens group, 1
Reference numeral 05 denotes a lens group (hereinafter referred to as a focus competition lens) having both a focus adjustment function and a so-called competition function for correcting movement of the focal plane due to zooming.

The image light transmitted through this lens system is
An image is formed on the imaging element 106 and converted into a video signal by photoelectric conversion. Reference numeral 107 is an amplifier or impedance converter, and 108 is a camera signal processing circuit. The video signal processed here is amplified to a prescribed level by an amplifier 109, processed by an LCD display circuit 110, and then used as an electronic viewfinder. The LCD 111 displays a captured image.

On the other hand, the video signal amplified by the amplifier 107 is also output to the aperture control circuit 112 and the AF evaluation value processing circuit 117. In the aperture control circuit 112, the IG driver 113 and the IG meter 114 are used depending on the video signal input level.
Is controlled to control the diaphragm 103 to adjust the light amount.

In the AF evaluation value processing circuit 117, according to the gate signal from the frame generation circuit 116 corresponding to the distance measuring frame,
Only the high frequency component of the video signal within the distance measurement frame is extracted and supplied to the AF microcomputer 115 as an AF evaluation value signal indicating sharpness according to the focus degree. The AF microcomputer 115 uses the AF
The drive control of the lens and the ranging frame control for changing the ranging area are performed according to the focus degree indicated by the evaluation value signal.

Reference numerals 118 and 120 denote drivers for outputting drive energy to a lens drive motor in accordance with drive instructions of the variable magnification lens group 102 and the focus compensation lens 105 output from the AF microcomputer 115, respectively. Reference numerals 119 and 121 denote the variable power lens group 1, respectively.
02, a motor for driving the focus compensation lens 105 in the optical axis direction.

When a stepping motor is used as the lens driving motor, the lens is driven as follows. That is, the AF microcomputer 115 outputs a motor rotation frequency signal corresponding to the lens moving speed and a motor rotation direction signal corresponding to the lens driving direction to the motor drivers 118 and 120. Motor driver 118, 1
Reference numeral 20 sets the phases of the four motor excitation phases to forward rotation or reverse rotation according to the rotation direction signal, and the applied voltage (or current) of the four motor excitation phases according to the rotation frequency signal. By outputting while changing
The rotation direction and rotation frequency of the motor are controlled. As a result, the stepping motors 119 and 121 rotate to drive the lens.

Reference numeral 122 denotes a wide attachment lens, which can be attached to and detached from the optical axis of the lens system by a lens slide mechanism 123, as shown by a broken line in FIG. And the wide attachment lens 1
Whether 22 is attached or not attached,
The detection signal is detected by the lens mounting detection switch 124, and the detection signal is supplied to the AF microcomputer 115.

[First Embodiment] Next, the algorithm of the focusing operation in the first embodiment will be described with reference to the flow chart of FIG.

First, the AF microcomputer 123 fetches the AF evaluation value signal from the AF evaluation value processing circuit 117 while slightly vibrating the focus compensating lens 105 by the wobbling operation (step S1) and blurs the focus at present. It is determined whether or not there is a front focus or a rear focus when there is blur (step S2). As a result, when the object is out of focus and is out of focus, a hill climbing operation in the direction of the determination result by the wobbling operation is executed (step S3). Then, it is determined whether or not the focal point, that is, the apex of the AF evaluation value signal is exceeded (step S
4) If not, go back to step S3 and continue the hill climbing operation.

On the other hand, if it exceeds the apex of the AF evaluation value signal, the focus compensating lens 105 is returned to the apex (step S5), and it is determined whether or not the apex of the AF evaluation value signal has been reached. (Step S6). As a result, if the vertex has not been reached, the process returns to step S5 and the operation of returning to the vertex is continued. On the other hand, when reaching the apex, the subject may change due to panning or the like while performing the operation of returning to the apex of the AF evaluation value signal. Then, in order to restart the focusing control, the process returns to step S1 and the wobbling operation is performed.

If it is determined in step S2 that the lens is in focus as a result of the wobbling operation, the focus compensating lens 105 is stopped and the process proceeds to the restart supervision routine from step S7. That is, first, step S7
At, the AF evaluation value signal level at the time of focusing is stored. Then, based on the detection signal from the lens attachment detection switch 124, it is determined whether or not the attachment state of the wide attachment lens 122 has changed (step S8). Here, the change in the mounted state means whether the wide attachment lens 122 has changed from the non-mounted state to the mounted state or from the mounted state to the non-mounted state.

When the mounting state of the wide attachment lens 122 changes, as described in the section of the conventional example, the position of the focus competition lens 105 which focuses on the subject at a predetermined distance is the wide attachment lens 122.
The focus compensating lens 105 must be restarted to find a new focal point. Therefore, when it is determined in step S8 that the mounting state of the wide attachment lens 122 has changed, the process returns to step S1 to perform the wobbling operation and focus control again.

On the other hand, the wide attachment lens 122
If the mounting state of No. has not changed, the normal restart monitoring process of step S9 is performed. That is, the current AF evaluation value signal level is the A at the time of focusing stored in step S7.
By comparing with the F evaluation value signal level and checking whether or not there is a change (step S9), it is determined whether or not restarting is required (step S10). For example, when the current AF evaluation value signal level fluctuates by a predetermined percentage or more with respect to the stored AF evaluation value signal level at the time of focusing, it is considered that there is a change in the subject due to panning or the like, and “restart” is performed. If the variation is less than the predetermined percentage, it is determined that there is no change in the subject and “no restart” is determined.

If it is determined in step S10 that "the camera will not restart", the focus compensating lens 105 is stopped as it is (step S11), the process returns to step S8, and restart monitoring is performed again. On the other hand, when it is determined to "restart", the process returns to step S1 and the wobbling operation is performed again to perform focusing control. By repeating such an operation, the movement of the focus compensating lens 105 is controlled so that the focus can be constantly maintained.

As described above, when the mounting state of the wide attachment lens 122 is changed, the focus control is forcibly restarted regardless of the restart monitoring based on the AF evaluation value signal, so that the AF process is completed. It is possible to save the time for determining whether to restart the focus control and improve the responsiveness. That is, when it is determined whether to restart the focusing control based on the AF evaluation value signal, after the mounting state of the wide attachment lens 122 is changed, the high frequency component in the changed state is captured and determined. Although it takes a predetermined time to start up, if a restart is forcibly performed when the mounting state of the wide attachment lens 122 changes as described above, at the moment when the mounting state changes, in other words, , A based on the video signal after the mounting state of the wide attachment lens 122 has changed
Rebooting is executed while the F evaluation value signal is being generated, and it is possible to quickly eliminate blurring that occurs when the mounting state changes.

[Second Embodiment] Next, the algorithm of the focusing operation in the second embodiment will be described with reference to the flowchart of FIG. The first embodiment is an example in which when the mounting state of the wide attachment lens 122 is changed, the blurring caused by the change of the mounting state is quickly eliminated by forcibly restarting the mounting state. Is an example in which, by forcibly climbing a mountain in the focusing direction according to a change in the wearing state, it is possible to more quickly and reliably eliminate the blurring that occurs when the wearing state changes.

The AF microcomputer 123 first determines whether or not the mounting state of the wide attachment lens 122 has changed based on the detection signal from the lens mounting detection switch 124 (step S21). As a result, when the wearing state changes, it is determined whether the change is a change from non-wearing (OFF) to wearing (ON) (step S22).

As a result, from non-wearing (OFF) to wearing (O
If it is a change to N), the focus competition lens 105
The moving direction of is set to the closest direction (step S23),
The process proceeds to step S28 described below. On the other hand, if the change is from mounting (ON) to non-mounting (OFF), the moving direction of the focus competition lens 105 is set to an infinite direction (step S24), and the process proceeds to step S28. It should be noted that the setting of the moving direction of the focus competition lens 105 according to the change in the mounting state of the wide attachment lens 122 as described above is performed when the wide attachment lens 122 is mounted, as shown in FIG. This is done in consideration of the fact that the position of the focus compensating lens 105 focused on the distance shifts to the closest direction.

If it is determined in step S21 that the mounting state of the wide attachment lens 122 has not changed, the AF evaluation value processing circuit 1 is caused by slightly vibrating the focus competition lens 105 by the wobbling operation.
The AF evaluation value signal is fetched from 17 (step S2
5) It is determined whether the object is currently in focus or out of focus (whether the object is in front of focus or behind in focus when out of focus) (step S26). As a result, when the object is out of focus and is out of focus, the direction of the determination result of the wobbling operation is set as the moving direction of the focus compensating lens 105 (hill climbing operation direction) (step S27), and step S2.
Proceed to 8.

In step S28, steps S23, 2
The mountain climbing operation in the direction set in 4, or 28 is executed. Then, it is determined whether or not the focal point, that is, the apex of the AF evaluation value signal is exceeded (step S29). If not, the process returns to step S28 to continue the hill climbing operation.

On the other hand, if it exceeds the apex of the AF evaluation value signal, the focus compensating lens 105 is returned to the apex (step S30), and it is determined whether or not the apex of the AF evaluation value signal has been reached. (Step S31).
As a result, if the vertex has not been reached, the process returns to step S5 and the operation of returning to the vertex is continued. On the other hand, when reaching the apex, the subject may change due to panning or the like while performing the operation of returning to the apex of the AF evaluation value signal.
In order to restart the focusing control to determine whether or not it is really the apex, that is, the in-focus point, the process returns to step S21, the mounting state of the wide attachment lens 122 is monitored, and the wobbling operation is performed.

If it is determined in step S26 that the object is in focus as a result of the wobbling operation, the focus compensating lens 105 is stopped, and the process proceeds to the restart supervision routine after step S32. That is, first, in step S32, the AF evaluation value level at the time of focusing is stored. Then, based on the detection signal from the lens mounting detection switch 124, it is determined whether or not the mounting state of the wide attachment lens 122 has changed (step S33).

As a result, when the mounting state changes, the focus compensating lens 10 moves in the direction corresponding to the mounting change.
In order to climb the mountain 5, the process proceeds to step S22. on the other hand,
If the mounting state has not changed, the normal restart monitoring process of step S34 is performed. That is, by checking whether or not the current AF evaluation value signal level has changed in comparison with the AF evaluation value signal level at the time of focusing stored in step S32 (step S34), whether or not restarting should be performed. Is determined (step S35). For example, when the current AF evaluation value signal level fluctuates by a predetermined percentage or more with respect to the stored AF evaluation value signal level at the time of focusing, it is determined that there is a change in the subject due to panning or the like, and “restart” is performed.
If the variation is less than the predetermined percentage, it is determined that there is no change in the subject and “no restart” is determined.

When it is determined in step S35 that "the camera will not be restarted", the focus compensating lens 105 is stopped as it is (step S36), the process returns to step S33, and restart monitoring is performed again. On the other hand, when it is determined that “restart”, the process returns to step S21,
Perform a reboot. By repeating such an operation, the movement of the focus compensating lens 105 is controlled so that the focus can be constantly maintained.

As described above, in the second embodiment, by forcibly climbing the mountain in the focusing direction according to how the wearing condition changes, blurring that occurs when the wearing condition changes can be performed more quickly. become. In particular, when the wobbling operation causes large blurring due to changes in the wearing condition, the AF evaluation value is buried in the noise level, and the focus direction cannot be recognized correctly, causing malfunction and blurring. It is possible to prevent the time taken to reach the end.

[0047]

As described above, according to the image pickup apparatus of the present invention, the first lens group for performing focus adjustment and the mounting / non-mounting on the same optical axis as the first lens group. By changing the mounting state of the second lens group, it is possible to freely change the mounting state of the mounting, and to have at least a second lens group for changing the focal length and the magnifying power by changing the mounting state. A lens system configured to change the position of the first lens group focused on a specific subject distance;
A sharpness signal corresponding to the degree of focus is extracted from a video signal obtained by photoelectrically converting an optical object image formed via the lens system, and movement control of the first lens group is performed based on the sharpness signal. And an in-focus control unit for performing in-focus control by moving the first lens group when the mounting state of the second lens group is changed. Since the restarting means for restarting the focusing control by the control means is provided, the position of the first lens group with respect to the subject at the same distance changes in accordance with the change of the mounting state of the second lens group. It is possible to quickly eliminate the blurring caused by.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a video-integrated camera to which an image pickup apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a focusing control operation in the first embodiment of the present invention.

FIG. 3 is a flowchart showing a focusing control operation in the second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an inner focus type lens system equipped with a wide attachment lens unit.

FIG. 5 is a diagram showing a locus representing a relationship between a zoom lens position for each object distance and a focus competition lens position for focusing in an inner focus type lens system.

FIG. 6 is a diagram showing a locus corresponding to FIG. 5 when a wide attachment lens is attached.

[Explanation of symbols]

Reference numeral 102 ... Variable magnification lens 105 ... Focus competition lens 106 ... Image sensor (CCD) 116 ... Frame generation circuit 115 ... AF microcomputer 117 ... AF evaluation value processing circuit 120 ... Driver (for focus competition lens) 121 ... Motor (for focus competition lens) ) 122 ... Wide attachment lens 123 ... Lens slide mechanism (for wide attachment lens) 124 ... Lens attachment detection switch (for wide attachment lens)

Claims (4)

[Claims] 1. A first lens group for performing focus adjustment, and a mounted state of mounted / not mounted on the same optical axis as the first lens group can be freely changed, and the mounted state can be changed. Position of the first lens group that has at least a second lens group for changing the focal length and the enlargement ratio, and focuses on a specific subject distance by changing the mounting state of the second lens group. A lens system configured to vary
A sharpness signal corresponding to the degree of focus is extracted from a video signal obtained by photoelectrically converting an optical object image formed via the lens system, and movement control of the first lens group is performed based on the sharpness signal. And an in-focus control unit for performing in-focus control by performing the in-focus control by moving the first lens group when the mounting state of the second lens group is changed. An image pickup apparatus comprising: a restarting unit that restarts focusing control by the control unit. 2. The restarting means has a detecting means for detecting a change in the mounting state of the second lens group, and the detecting means detects the change in the mounting state of the second lens group. The image pickup apparatus according to claim 1, wherein the first lens group is moved to restart the focusing control by the focusing control unit. 3. The focusing control means for moving the first lens group in a predetermined direction according to the changed state when the mounting state of the second lens group is changed. The image pickup apparatus according to claim 1, wherein the focus control according to step 1 is restarted. 4. The restarting means moves in the close-up direction when the second lens group is changed from the mounted state to the non-mounted state, and in the infinite direction when the second lens group is changed from the non-mounted state to the mounted state. 4. The focusing control by the focusing control means is restarted by moving the first lens group.
The imaging device described.