JP2016200674A - Lens control device and lens control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an appropriate angle of view control according to a photographing situation. A lens control device includes an operating member for moving a variable power lens, a detecting means for detecting an operating speed of the operating member, and a variable power lens based on an operating speed of the operating member based on a predetermined correlation characteristic. Calculation means for calculating the target moving speed, setting means for setting a predetermined correlation characteristic, and determination means for determining the shooting state based on information on the subject detected from the image. When the determination unit determines that the predetermined shooting state is set, the setting unit sets a predetermined correlation characteristic different from the case where it is determined that the predetermined shooting state is not set. [Selection] Figure 7

Description

  The present invention relates to a lens control device that detects an operation for moving a lens and controls driving of the lens.

  Conventionally, a technique for determining a moving amount of a lens such as a zoom lens system based on an operating amount of an operating member (for example, a ring operating member provided concentrically with respect to a lens optical axis) is known. Normally, during still image shooting, it is required to quickly move the zoom lens with a good response to the operation amount of the operation member so that the angle of view desired by the photographer is immediately obtained. On the other hand, at the time of moving image shooting, if a change in the angle of view that is too steep with respect to the operation amount of the operation member occurs, an unsightly captured image may be obtained. Thus, the drive control required for the zoom lens may vary depending on the scene.

  Japanese Patent Application Laid-Open No. 2004-133830 discloses switching zoom response characteristics with respect to an operation of a zoom ring in accordance with a shooting situation. For example, in the recording state, by changing the moving speed of the zoom lens in accordance with the rotation speed of the zoom ring, an effective zooming effect that matches the human sense can be obtained.

  Here, the operation of the ring operation member and the movement of the zoom lens will be described. FIG. 8 is a diagram showing a configuration example of zoom control by operation of the ring operation member. The operation ring encoder 20 detects the operation amount of the ring member, and the ring speed detection unit 23 detects the operation speed. Based on the output of the ring speed detection unit 23, the zoom target speed setting unit 9 sets the target speed of the zoom lens. Here, in order to change the correlation characteristic between the ring speed and the zoom target speed in the zoom target speed setting unit 9, a digital low-pass filter (LPF) processing unit 9a is provided. By applying digital LPF processing to the output of the ring speed detection unit 23 and using it for calculation of the zoom target speed in the zoom target speed calculation unit 9b, a sharp change in ring operation can be suppressed. Then, the zoom control unit 11a controls the zoom lens to change the angle of view of the camera so that the target speed set by the zoom target speed setting unit 9 is obtained.

  FIG. 9 shows an example of the relationship between the ring operation amount and the zoom angle of view change. In the output 901 of the operation ring encoder 20 provided on the ring operation member, the section in which the signal is switched between High / Low indicates that the ring operation member is operated, and the period of the signal is the ring operation member's cycle. The ring operation speed is shown. The ring operation speed 902 indicates the output of the ring speed detection unit 23. Since the ring operation speed 902 is subjected to LPF processing by the LPF processing unit 9a, the zoom target speed 913 changes smoothly when the zoom starts or stops, and fine speed changes due to ring operation variations are also smoothed. . A smooth change in the angle of view 914 is realized by driving the zoom lens using the zoom target speed.

JP 10-39192 A

  However, controlling the angle of view to be moderate may cause a problem of the angle of view when zooming is stopped. In FIG. 9, the output of the operation ring encoder 20 is stopped at the timing 915, and it can be seen that the photographer has stopped operating the ring. Since the operation ring has stopped, the ring operation speed 902 also becomes zero at timing 916 (corresponding to timing 915). On the other hand, since LPF processing is performed in order to suppress a steep zoom speed change, even if the ring operation speed 902 becomes zero at the timing 916, the zoom target speed 913 at that time does not become zero and gradually decreases. (917). Along with this, the change in the angle of view gradually becomes gentle, and finally the zoom lens stops at the position of the angle of view 918.

  Here, since the photographer stops the ring operation at the timing 915, it is estimated that the photographer tried to stop the zoom lens at an angle of view close to the angle of view 919 displayed at that time. However, since the actual stop angle of view is the angle of view 918, an angle of view difference 920 occurs. For this reason, for example, when performing a zoom-in operation by capturing a moving subject within the angle of view, the subject is framed out due to a change in the angle of view from when the photographer stops the ring operation until the zoom lens actually stops. There is a risk of it.

  In view of the above-described problems, an object of the present invention is to enable appropriate angle-of-view control according to a shooting situation.

  In order to achieve the above object, the present invention provides an operation member for moving a zoom lens, detection means for detecting an operation speed of the operation member, and operation of the operation member based on a predetermined correlation characteristic. A calculating unit that calculates a target moving speed of the zoom lens from a speed; a setting unit that sets the predetermined correlation characteristic; and a determining unit that determines a shooting state based on information on a subject detected from an image. In the lens control device, when the determination unit determines that the predetermined shooting state is set, the setting unit sets the predetermined correlation characteristic different from the case where it is determined that the predetermined shooting state is not set It is characterized by that.

  According to the present invention, it is possible to appropriately control the angle of view according to the shooting situation.

The figure which shows the structure of the digital camera which concerns on this embodiment. The figure which shows the structure of the zoom control by ring operation in this embodiment. The figure which shows the relationship between the ring operation amount in this embodiment, and zoom angle of view change. The figure which shows an example of the mode of a view angle change in this embodiment The figure explaining the setting of the cut-off frequency A flowchart showing zoom drive control processing Flow chart showing low-pass filter processing The figure which shows the conventional composition of zoom control by ring operation The figure which shows the relationship between the amount of ring operations corresponding to the structure of FIG. 8, and zoom angle of view change The figure explaining the subject which arises by the conventional composition

  Hereinafter, embodiments of the present invention will be described in detail. The embodiment described below is an example as means for realizing the present invention, and the present invention is not limited to the embodiment.

  FIG. 1 shows a configuration example of a digital camera 1 as an example of an image pickup apparatus including a zoom control device according to the present embodiment. The lens barrel 10 holds therein a lens group such as a zoom lens (magnification lens) 10a and a focus lens 10b. The zoom lens 10a is driven and controlled by the lens control unit 11, and optically changes the angle of view (zoom optical magnification, focal length). The focus lens 10b is driven and controlled by the lens control unit 11 to adjust the focus. The lens control unit 11 includes a zoom control unit 11a that controls driving of the zoom lens 10a and a focus control unit 11b that controls driving of the focus lens 10b. The driving amount and driving speed of the zoom lens 10 a are calculated by the system controller 8 and the zoom target speed setting unit 9. Note that the focus lens 10b and the focus control unit 11b are not essential components of the present invention.

  The image sensor 12 receives light that has passed through the lens barrel 10, converts an optical image into an electrical signal, and outputs an image signal. The timing of the image sensor 12 is controlled by the imaging control block 13. The image processing circuit 14 performs predetermined pixel interpolation processing and color conversion processing on the imaging signal output from the imaging device 12. The image data processed by the image processing circuit 14 is temporarily stored in the buffer memory 17, and the memory control unit 15 stores and deletes the image data in the buffer memory 17. The subject detection unit 16 extracts a subject from the image data stored in the buffer memory, acquires information such as the size and position of the subject, and calculates their temporal change amount. The image display unit 7 displays captured images, various menus, guides, and the like. The storage memory 18 finally stores the image data.

  The system controller 8 controls the entire digital camera 1. The power button 2, the release button 3, and the menu operation button 4 are operation means for inputting various operation instructions of the system controller 8. The operation means is composed of one or a plurality of combinations such as a switch, a dial, and a touch panel. By operating the power button 2, a signal serving as a trigger for turning on / off the power supply to the digital camera 1 is output. By operating the release button 3, a trigger signal for operating a shutter for recording a still image and a trigger signal for starting and stopping moving image recording are output. The menu operation button 4 is used for various settings of the camera. A ring-shaped operation member (hereinafter referred to as a ring operation member or operation ring) 6 is provided concentrically with the optical axis of a photographing optical system configured using a lens group, and can be rotated by a photographer's operation. .

  The operation ring encoder 20 outputs an operation amount of the ring operation member 6. In the ring operation amount detection unit 21, based on the output of the operation ring encoder 20, the rotation angle of the ring operation member 6 is detected by the ring angle detection unit 22, and the rotation speed of the ring operation member 6 is detected by the ring speed detection unit 23. To do.

  FIG. 2 shows a configuration example of zoom control by operating the ring operation member 6 in the present embodiment. In FIG. 2, a cutoff frequency setting unit 9c for setting a cutoff frequency of the LPF processing unit 9a is provided in the example of FIG. The cut-off frequency is determined based on subject information such as the position and size of the subject output by the subject detection unit 16 and the amount of temporal change thereof.

  Here, a scene where the above-described problem is assumed to be generated will be described with reference to FIG. FIG. 10 is a diagram for explaining a problem that may occur due to the angle-of-view difference 920 described with reference to FIG. In FIG. 10, while the zoom lens 10a is moved from the wide-angle side to the telephoto side to zoom in on the subject, the captured images 1001a to 1001e in each frame and the subjects 1002a to 1002 reflected in each image in time series. e is shown.

  First, as shown in the photographed image 1001a, it is assumed that the photographer intentionally operates the ring operation member 6 to start the zoom operation in a state where the subject 1002a is shown small relative to the angle of view. As the zoom lens 10a moves to the telephoto side, the subject gradually increases with respect to the angle of view. The photographer stops the operation of the ring operation member 6 at a timing 1004 when the subject becomes a desired size with respect to the angle of view. At this time, in the case of the processing described with reference to FIG. 9, the zoom target speed is gradually reduced, so that the zoom lens 10a does not stop immediately. As a result, the angle of view at the timing 1005 at which the zoom lens 10a finally stops deviates from the angle of view at the timing 1004 at which the operation of the ring operation member 6 is stopped. Therefore, in the captured image 1001e at the timing 1005, the subject 1002e may protrude from the angle of view, and the angle of view may be over.

  In the present embodiment, the following processing is performed for the above problem. FIG. 3 shows an example of the relationship between the ring operation amount and the zoom angle change in the present embodiment. In FIG. 3, as in FIG. 9, the output 301 of the operation ring encoder 20 for detecting the operation amount of the ring operation member 6, the change in the ring operation speed 302 and the zoom target speed 303 at that time, and the angle of view 304 at that time. Shows changes. Also here, it is assumed that the ring operation by the photographer is stopped at the timing 305 and the ring operation speed 302 becomes zero.

  In the present embodiment, after the photographer stops the ring operation, the subject information is acquired from the subject detection unit 16, and the cutoff frequency of the LPF processing unit 9a is changed based on the information. Although details of the change of the cut-off frequency will be described later, in FIG. 3, the cut-off frequency is changed at the timing 306, thereby increasing the attenuation rate of the zoom target speed 303. As a result, the change in the angle of view 304 converges faster than in the example of FIG. 9, and the angle of view 308 that finally stops is also close to the angle of view 307 when the ring operation is finished.

  With reference to FIG. 4, how the angle of view changes in FIG. 3 will be described in detail. In FIG. 4, as in FIG. 10, while the zoom lens 10 a is moved from the wide-angle side to the telephoto side to zoom in on the subject, the captured images 401 a to e of each frame and each Subjects 402a to e appearing in the image are shown.

  Similarly to FIG. 10, as shown in the photographed image 401 a, the photographer intentionally operates the ring operation member 6 to perform a zoom operation at a timing 403 in a state where the subject 402 a appears small with respect to the angle of view. Suppose you start it. In FIG. 4, when the photographer stops the operation of the ring operation member 6 at the timing 404, the cutoff frequency of the LPF is changed based on the subject information acquired from the subject detection unit 16, and the ring speed, the zoom target speed, Correlation characteristics of are changed.

  FIG. 5 is a diagram for explaining the cutoff frequency change at that time, and shows the captured image 401d of FIG. At this time, the position and size of the subject 402d are indicated by a frame 406. In addition, a determination area 407 is set in a predetermined area in the captured image. The determination area 407 is an area used by the cut-off frequency setting unit 9c for determination to change the cut-off frequency, and the cut-off frequency is determined based on the relationship between the determination area 407 and the subject position.

  For example, when the frame 406 of the subject is within (included in) the determination area 407 while the ring operation member 6 is stopped, the cut-off frequency is set low so that the zoom target speed and the angle of view change smoothly. Set to the first value. On the other hand, when the subject frame 406 deviates from the determination area 407 (outside the predetermined area), the cutoff frequency is set to a second value higher than the first value. By setting the cut-off frequency high, the responsiveness of the zoom target speed and the zoom field angle change with respect to the ring operation speed increases, and the field angle change stops earlier (405). As a result, even if the subject is likely to exceed the angle of view, such as performing a zoom-in operation on a moving subject, the subject 402e can be contained within the angle of view as in the captured image 401e.

  The determination condition for setting the cutoff frequency to the second value may be a case where at least a part of the subject frame 406 is out of the determination area 407, or a predetermined ratio of the subject frame 406. It is good also as a case where the above deviated from the determination area 407. In the example of FIG. 5, the frame 406 is set for the whole body area of the person subject. However, for example, the frame 406 may be set for the face area of the person subject or set for a subject other than the person. May be. Further, a configuration may be adopted in which the photographer can change the setting of the subject frame 406 from a menu screen or the like. Alternatively, without setting the frame 406, it may be determined whether the image area determined to be the subject area has deviated from the determination area 407.

  Further, although the method for determining the cutoff frequency based on the relationship between the determination area 407 and the subject position has been described above, the cutoff frequency may be determined based on the size of the subject. In this case, for example, a method of increasing the cutoff frequency when the size of the subject in the image is larger than a predetermined size can be considered.

  Next, a processing flow in the present embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart showing the flow of zoom drive control.

  First, in step S601, the ring speed detection unit 23 detects the ring operation speed of the ring operation member 6. An LPF process, which will be described later, is performed on the detected ring operation speed in step S602. In step S603, the ring operation speed subjected to the LPF process is converted into a zoom speed value.

  In step S604, the zoom target speed calculation unit 9b sets a zoom target speed (target movement speed) based on the zoom speed value. The zoom target speed set here is the final target speed in driving the zoom lens in step S609.

  In step S605, the zoom target speed setting unit 9 (system controller 8) determines whether or not the zoom target speed set in step S604 is a drivable speed. Specifically, it is determined whether or not the set zoom target speed is smaller than the lowest drivable speed. This is because the speed limit that can be driven on the low speed side is determined depending on the actuator that drives the zoom lens 10a. If the zoom target speed is equal to or higher than the drivable minimum speed, the process proceeds to step S609, and the zoom control unit 11a drives and controls the zoom lens 10a based on the zoom target speed set in step S604.

  On the other hand, when the zoom target speed is smaller than the lowest drivable speed, in step S606, the system controller 8 determines whether or not the ring operation member 6 is being operated. If the ring operation is being performed, the process proceeds to step S607, and the zoom target speed setting unit 9 sets the zoom target speed to the lowest drivable speed. In this case, in step S609, the zoom lens 10a is driven and controlled by the zoom control unit 11a based on the zoom target speed set in step S607. On the other hand, if the ring operation is stopped, the process proceeds to step S608, and the system controller controls the zoom control unit 11a to stop the zoom lens 10a.

  Next, the LPF process performed in step S602 will be described. FIG. 7 is a flowchart showing the flow of LPF processing. In the LPF process, first, in steps S701 to S709, a cutoff frequency is set according to the photographing state, and the LPF process is performed in step S710 based on the set cutoff frequency.

  First, in step S701, the system controller 8 determines the set shooting mode. In the case of the still image mode, the process proceeds to step S709, and in the case of the moving image mode (mode for recording a moving image), the process proceeds to step S702.

  In the case of the still image mode, the quick movement of the zoom lens that follows the movement of the ring operation member 6 is required. Therefore, in step S709, the cutoff frequency setting unit 9c sets the cutoff frequency of the LPF to “high”. In this case, the LPF process may not be performed.

  On the other hand, when the process proceeds to step S702, the system controller 8 determines whether or not the ring operation member 6 is being operated. As described above, in the moving image mode, a sharp change in the angle of view is disliked, so the cut-off frequency is set lower than in the still image mode (step S709). When the ring operation is being performed, the process proceeds to step S707, and the cutoff frequency setting unit 9c sets the cutoff frequency of the LPF to “low”. Thereby, the ring speed value used for calculation of the target speed is smoothly changed.

  On the other hand, when the ring operation is stopped, the process proceeds to step S703, and the system controller 8 acquires subject information from the subject detection unit 16. Here, information including at least one of the position and size of the subject is acquired, and information about the amount of time change is also acquired. Information about the time change amount may be calculated by the system controller 8.

  In step S704, the system controller 8 detects the change speed of the angle of view based on the current zoom speed and focal length. In step S705, the system controller 8 sets a determination area 407 used for determination of the cutoff frequency based on the subject information acquired in step S703 and the angle of view change speed detected in step S704. For example, the determination area 407 is set smaller than usual when the movement of the subject is fast or when the angle of view change speed is large. This is because the cut-off frequency is changed at a timing earlier than usual under conditions where the angle of view of the subject is likely to exceed. As a result, the risk of the subject's field angle being exceeded can be further reduced. The speed of the subject corresponds to one or both of the moving speed in the screen (time change amount of the subject position) and the moving speed in the distance direction (time change amount of the subject size). .

  As described above, in FIG. 7, the method of setting the determination area 407 based on both the subject information and the angle of view change speed has been described. Even if the determination area 407 is set based only on the subject information, the effect of preventing the angle of view from being exceeded can be obtained, so that the object of the present invention can be achieved. It is possible to effectively prevent the angle of view from being exceeded. In addition to the angle of view change speed, the determination area 407 may be set by determining other conditions that are likely to cause a frame-out, such as when the camera shake amount is large.

  Further, the determination area 407 may be set based on the zoom speed (actuator driving speed or moving speed of the zoom lens 10a) without calculating the angle of view change speed in step S704. In this case, based on both the zoom speed and the focal length, for example, even when the zoom speed is the same, the determination area 407 may be set smaller in the case of the telephoto side.

  In step S706, the system controller 8 determines whether the subject is within the determination area 407 set in step S705. The determination method here is the same as the method described above with reference to FIG. If the subject area is outside the determination area 407, the process proceeds to step S708. If the subject area is within the determination area 407, the process proceeds to step S707. In step S708, the cutoff frequency setting unit 9c sets the cutoff frequency of the LPF to “medium”, which is higher than that in step S707. By setting the cut-off frequency higher than normal, the zoom angle of view can be converged earlier, so that the subject can be prevented from exceeding the angle of view contrary to the photographer's intention. . Note that the cutoff frequency set in step S708 is lower than the cutoff frequency set in step S709.

  If the cut-off frequency is set in any of steps S707, S708, and S709, the process proceeds to step S710. In step S710, based on the set cutoff frequency, the LPF processing unit 9a performs digital low-pass filter processing, and the processing ends.

  In the present embodiment, the technique of changing the LPF and its cutoff frequency is used as a technique for changing the correlation characteristics between the operation speed of the ring operating member 6 and the zoom target speed, but the present invention is not limited to this technique. For example, a method of formulating correlation characteristics and changing coefficients thereof, or a method of preparing a plurality of correlation tables and switching them may be used.

  As described above, in the present embodiment, processing for increasing the response of the zoom target speed to the operation amount of the ring operation member is performed if the subject is likely to have an angle of view over. As a result, even when the zoom lens is controlled so as to smoothly change the angle of view, the responsiveness of the change in the angle of view can be enhanced under conditions where the subject is likely to exceed the angle of view. Appropriate angle of view control can be realized.

  As mentioned above, although this invention was explained in full detail based on the suitable embodiment, this invention is not limited to specific embodiment, Various forms of the range which does not deviate from the summary of this invention are also included in this invention. .

DESCRIPTION OF SYMBOLS 1 Digital camera 6 Ring operation member 8 System controller 9 Zoom target speed setting part 10a Zoom lens 11a Zoom control part 20 Operation ring encoder 21 Ring operation amount detection part

Claims (15)

An operation member for moving the zoom lens;
Detecting means for detecting an operation speed of the operation member;
A calculating means for calculating a target moving speed of the zoom lens from an operating speed of the operating member based on a predetermined correlation characteristic;
Setting means for setting the predetermined correlation characteristic;
A determination means for determining a shooting state based on information of a subject detected from an image;
When the determination unit determines that the predetermined shooting state is set, the setting unit sets the predetermined correlation characteristic different from the case where it is determined that the predetermined shooting state is not set. apparatus.   The lens control device according to claim 1, wherein the predetermined shooting state is a state in which the subject is more likely to deviate from the angle of view as compared to a case where the predetermined shooting state is not set.   The setting means, when it is determined that the predetermined photographing state is determined, compared with a case where it is determined that the predetermined photographing state is not satisfied, the target movement of the zoom lens with respect to the operation speed of the operation member The lens control apparatus according to claim 1, wherein the predetermined correlation characteristic is set so that responsiveness of a change in speed is increased. A low-pass filter to which the value of the operation speed of the operation member detected by the detection means is input;
4. The lens control device according to claim 1, wherein the setting unit sets a cutoff frequency of the low-pass filter as the predetermined correlation characteristic. 5.   The setting unit sets the cut-off frequency to a first value when it is not determined that the predetermined shooting state is set, and the cut-off when it is determined that the predetermined shooting state is set. The lens control device according to claim 4, wherein the frequency is set to a second value higher than the first value.   The determination unit sets a predetermined area within an angle of view, and determines that the predetermined shooting state is set when at least a part of a subject is detected outside the predetermined area. Item 6. The lens control device according to any one of Items 1 to 5.   The lens control device according to claim 1, wherein the determination unit changes a size of the predetermined area according to a speed of a subject.   8. The determination unit according to claim 7, wherein when the speed of the subject is a second speed higher than the first speed, the predetermined area is set larger than the case of the first speed. The lens control device described in 1.   7. The determination unit changes the size of the predetermined region in accordance with a driving speed of the zoom lens or a change speed of an angle of view based on the driving speed of the zoom lens. The lens control device according to any one of 1 to 8.   The determination unit determines the predetermined area when the driving speed of the zoom lens or the change speed of the angle of view is a fourth speed higher than the third speed, compared to the third speed. The lens control device according to claim 9, wherein the lens control device is set large.   The lens control according to any one of claims 1 to 10, wherein the determination unit determines whether or not the predetermined photographing state is set when the operation of the operation member is stopped. apparatus.   In the mode for capturing a still image, the setting means is more responsive to the change in the target moving speed of the variable power lens with respect to the operation speed of the operation member than in the mode for capturing a moving image. The lens control apparatus according to claim 1, wherein the predetermined correlation characteristic is set as described above.   13. The lens control device according to claim 12, wherein the determination unit determines whether or not the predetermined shooting state is set in a mode for shooting the still image.   14. The lens control device according to claim 1, wherein the operation member is a ring-shaped member provided concentrically with respect to an optical axis of the zoom lens. A detection step for detecting an operation speed of the operation member for moving the zoom lens;
A calculation step of calculating a target moving speed of the zoom lens from an operating speed of the operating member based on a predetermined correlation characteristic;
A setting step for setting the predetermined correlation characteristic;
A determination step of determining a shooting state based on information on a subject detected from an image;
When the determination step determines that the predetermined shooting state is set, the setting step sets the predetermined correlation characteristic different from the case where the predetermined shooting state is not determined. Method.

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