JP2007148075A - Lens driving device and lens driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device and a lens driving method with which image change is smoothly performed so that a user does not feel incompatibility and quick zooming operation is performed even when the zooming operation is performed by switching and driving two or more lenses in consecutively taking pictures and taking a still picture. <P>SOLUTION: The lens driving device of a camera module has: a zoom lens; a focus lens; a first driving means and a second driving means for alternately driving the zoom lens and the focus lens; a detection means for detecting a kind of photography; and a control means for varying switching timing in the alternate driving of the zoom lens and the focus lens, based on the result of detection by the detection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device and a lens driving method for driving a plurality of lenses.

  2. Description of the Related Art In recent years, various portable devices such as a mobile phone that incorporates a module having a camera function and can capture moving images and still images have been developed. In these portable devices, since the camera function is used in various situations, it is desired to have a zoom function.

  In a camera module having an optical zoom function capable of shooting moving images and still images, a zoom lens that moves to enlarge a subject during a zoom operation and a focus shift that occurs due to the movement of the zoom lens are corrected. In order to drive the focus lens that moves to the center, there are some that have built-in individual motors.

  Here, in order to smooth the image change in a state where the focus is always on and to realize a quick zoom operation so that the user does not feel uncomfortable at the time of shooting, a control method of simultaneously driving a plurality of motors may be taken. desirable.

  However, some devices that require a large amount of power consumption such as displays, call modules, and multiprocessors must be installed in a limited space, and the size of the battery is limited. For the camera module to be used, space saving and power saving are strongly desired.

In order to solve these problems, for example, in Patent Document 1 and Patent Document 2, two or more motors are alternately switched and driven by time division, and the number of motors operating at the time of zoom operation is always one. Power saving is realized. In addition, since only one power supply circuit for driving the motor is required in the above structure, it is possible to mount in a space-saving manner compared to the case where two or more motors are driven simultaneously.
JP-A-6-138358 JP-A-10-197779

  In Patent Document 1 and Patent Document 2 described above, it is necessary to frequently switch between driving of the zoom lens and driving of the focus lens in order to perform the zoom operation in a focused state where the image change is smooth. If the number of times of switching between the lens drive and the focus lens drive is increased, there is a problem that the zoom operation speed decreases.

  Here, in a lens driving device having different shooting types such as continuous shooting and still image shooting, for example, when performing continuous shooting, a quick zoom operation is particularly required with a smooth image change.

  However, in the conventional example, there is a problem that a difference in required performance is not considered in the case of different shooting types such as continuous shooting and still image shooting.

  The present invention has been made in view of the above-described problems in the prior art, and its purpose is to perform a zoom operation by switching two or more motors to drive two or more lenses. By controlling the switching of each lens drive based on the frame rate or display resolution, the image changes smoothly and does not give the user a sense of incongruity in both continuous shooting and still image shooting. It is an object of the present invention to provide a lens driving device and a lens driving method that can be performed.

  In order to achieve the above object, a lens driving device according to the present invention includes a zoom lens, a focus lens, a first driving unit that drives the zoom lens and the focus lens, and a first driving unit, respectively. And a control unit that changes a switching timing of alternate driving of the zoom lens and the focus lens based on a detection result by the detection unit. To do.

  In the lens driving device of the present invention, the detection means is means for detecting whether the photographing by the camera module is continuous photographing or still image photographing.

  Further, the lens driving device of the present invention detects whether the shooting by the camera module is continuous shooting or still image shooting, and the switching timing in the case of continuous shooting is the switching timing in the case of still image shooting. The switching timing of the alternate driving of the zoom lens and the focus lens is controlled so as to be faster.

  The lens driving device of the present invention is characterized in that the switching timing is controlled so that at least the switching period of the alternate driving of the zoom lens is earlier at the end of driving than at the start of driving.

  The lens driving device of the present invention is characterized in that, in the lens driving device of the camera module, the number of times of alternating driving of the zoom lens and the focus lens is controlled according to the type of photographing.

  Further, the lens driving device of the present invention is characterized in that the switching timing of the alternate driving of the zoom lens and the focus lens is set according to the recording resolution during continuous shooting.

  Further, the lens driving device of the present invention is characterized in that the switching timing of the alternate driving of the zoom lens and the focus lens is set according to the frame rate during continuous shooting.

  The lens driving device according to the present invention is characterized in that, at the time of still image shooting, the switching timing for alternately driving the zoom lens and the focus lens is set according to the resolution of the display unit.

  In addition, the lens driving device of the present invention is characterized in that the switching timing of the alternate driving of the zoom lens and the focus lens is arbitrarily set during still image shooting.

  The lens driving method of the present invention is characterized in that the lens is driven using the lens driving device.

  As is clear from the above, according to the lens driving device and the lens driving method of the present invention, even when zooming is performed by alternately driving two or more motors, continuous shooting and still image shooting are performed. At any time, it is possible to maintain a smooth image change and to perform a quick zoom operation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a block diagram showing main components of a lens driving device according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a control unit that performs camera calculation, sequence control, and the like. The control unit 10 is configured to set a camera mode by operating a shooting mode starting unit 11 provided on an operation panel unit of the camera. A signal is input. Further, the camera is provided with a shooting type setting means 17 for setting a shooting type such as whether the user is shooting continuously or still image depending on the shooting situation, and is set by the shooting type setting means 17. The state is detected by the detection means 12 which photographing type has been selected. The detection means 12 can also be configured to be built in the control unit 10. The control unit 10 is connected to a first control unit 13 and a second control unit 15 that are controlled by an output signal of the control unit 10. The first control means 13 drives the zoom lens 15, and the second control means 14 drives the focus lens 16.

  The control unit 10 includes a storage unit that holds a frame rate and a recording resolution set by the user when continuous shooting is selected. The frame rate and recording resolution can be input from numerical keys in, for example, a mobile phone. Alternatively, the frame rate or the recording resolution prepared in advance in the device can be selected, and this selection information can be held in the storage means.

  Further, the control unit 10 includes a storage unit that holds display resolution information and a zoom speed of an image displayed in real time on the display unit when still image shooting is selected. The display resolution and zoom speed may be set in advance by the device, or may be set by the user.

  First, the photographing mode starting unit 11 is operated to input a signal to the control unit 10. Next, the preset photographing type is detected by the detecting means 12. Subsequently, the first control unit 13 and the second control unit 14 are controlled by signals from the control unit 10 based on the detection result by the detection unit 12 to drive the zoom lens 15 and the focus lens 16, respectively. . Here, the shooting type setting unit 17 may be operated after the shooting mode start unit 11 is operated, or the shooting type setting unit 17 may be built in the shooting mode start unit 11.

  Next, with reference to FIG. 2, a description will be given of a case where photographing is performed using the lens driving device according to the first embodiment of the present invention.

  FIG. 2 is a flowchart showing a lens driving method according to an embodiment of the present invention. The lens driving method according to the present invention will be described below according to the flowchart.

  In the following description, the zoom lens 15 and the focus lens 16 are driven to perform a zoom operation. Here, the zoom lens 15 and the focus lens 16 may be a single lens composed of a single lens or a lens group composed of a plurality of lenses.

  First, at the start of processing, in step S1, whether to select continuous shooting or still image shooting is set by the shooting type setting means 17 in advance.

  Next, the shooting mode is started by operating the shooting mode starting means 11 in step S2.

  Here, the order of step S1 and step S2 can be interchanged. That is, it is also possible to configure so that the shooting type is set after the shooting mode is started.

  Next, the process proceeds to step S3, and the detection type is detected by the detection means 12.

  Examples of shooting types include continuous shooting and still image shooting. During continuous shooting, it is necessary to increase the number of times the zoom lens and the focus lens are switched alternately in order to shoot a smooth image, and it is necessary to focus frequently. In addition, the operating time can be shortened. Required.

  On the other hand, at the time of still image shooting, it is only necessary to be in focus at the time of recording after stopping the zoom operation, and it is not always necessary to focus during the zoom operation. If the camera is not in focus during the zoom operation, an in-focus image will be displayed on the display during the zoom operation, but the focus lens will be driven and focused by the time of recording. Still image shooting is possible.

  With reference to FIG. 3, description will be given of lens driving in each case of continuous shooting and still image shooting.

  FIG. 3 shows an example of the mutual drive switching timing of the zoom lens and the focus lens.

  3A shows the driving state of the zoom lens during continuous shooting, FIG. 3B shows the driving state of the focus lens during continuous shooting, and FIG. 3C shows the zoom lens and focus lens during continuous shooting. The states of mutual drive are shown respectively. The zoom lens and the focus lens are each driven four times during the zoom operation, indicating that the operation ends at time T1.

  Similarly, FIG. 3D is a zoom lens driving state during still image shooting, FIG. 3E is a focus lens driving state during still image shooting, and FIG. 3F is a zoom lens driving during still image shooting. And the state of mutual drive of the focus lens. A time T2 indicates a time at which the zoom operation at the time of still image shooting ends.

  When shooting a still image, it is only necessary to be in focus during recording after the zoom operation is completed, and it is not always necessary to focus during the zoom operation. Good.

  Here, in general, a lens drive motor is composed of a magnet attached to a rotating shaft and an electromagnet fixed, and is magnetized by passing an electric current through the electromagnet, and rotates by attracting the magnet of the rotating shaft. Often, a stepping motor is used. In that case, in order to control the rotation angle with high accuracy, it is necessary to pass a current through the motor coil for a certain period of time when the motor is stopped and when the motor is started to maintain the coil position. Δt in FIG. 3 indicates the time required to hold the positions of the zoom lens and the focus lens.

  During continuous shooting, it is necessary to maintain a clear image during recording. Therefore, it is necessary to increase the number of times of alternate driving of the zoom lens and the focus lens, and a lens holding time Δt is required for each lens switching. Therefore, the time T1 required for zooming in continuous shooting is longer than the time T2 required for zooming in still image shooting with a small number of times of switching between alternate driving of the zoom lens and the focus lens.

  Therefore, by controlling the switching frequency of the alternate lens driving according to the photographing type, it is possible to maintain a smooth image change and perform a quick zoom operation.

  Since the required performance varies depending on the photographing type as described above, the required performance varies depending on the photographing type by detecting the photographing type by the detecting unit 12 and changing the timing of alternately driving the zoom lens and the focus lens based on the detection result. Accordingly, it is possible to drive the lens in accordance with the above, maintain a smooth image change, and perform a quick zoom operation.

  If it is detected in step S3 that continuous shooting is performed by the detection means 12, the process proceeds to step S4, whereas if it is detected that still image shooting is performed, the process proceeds to step S5.

  When the process proceeds to step S4, the frame rate information set by the user is acquired. In continuous shooting, the frame rate indicates the number of renderings per second. For example, when shooting and recording is performed during a zoom operation of 1 second at a frame rate of 15 fps (Frame Per Second), an image of 15 frames is displayed. Will be recorded. Smoother continuous shooting is possible as the frame rate increases. However, since the amount of data necessary for recording increases as the frame rate increases, the user generally sets the frame rate according to the purpose.

  Here, for example, when the frame rate is set to 15 fps, the zoom lens and the focus lens are alternately switched at a speed of 15 times per second, and the recording timing and the in-focus timing are adjusted to match the recording timing. Focusing is possible, and it is possible to obtain a photographing result in the best state.

  Further, in actual shooting, it is not necessary to make the frame rate and the switching frequency of the lens mutual drive the same, and by setting the switching timing of the lens mutual driving according to the frame rate information obtained in step S4 of FIG. Thus, a zoom operation without a sense of incongruity is possible with a minimum number of switching times.

  Therefore, it is possible to drive the lens without waste by setting the switching timing of the alternate driving of the zoom lens and the focus lens according to the frame rate during continuous shooting, realizing a reduction in operating time and real time. And smooth images can be recorded.

  In step S6, recording resolution information set by the user is acquired. In continuous shooting, as with the frame rate, the user generally sets the recording resolution according to the purpose.

  Table 1 is a table showing an example of the recording resolution of the shooting screen at the time of continuous shooting in the lens driving device of the camera module.

表１において、Ａは記録解像度６４０×４８０、Ｂは記録解像度３２０×２４０、Ｃは記録解像度１６０×１２０の場合をそれぞれ示す。また、それぞれ場合の記録解像度を実現するために必要な許容錯乱円径をそれぞれＲａ、Ｒｂ、Ｒｃとすると、一般的にＲｂ＝Ｒａ×２、Ｒｃ＝Ｒａ×４の関係が成り立つ。

In Table 1, A indicates a recording resolution of 640 × 480, B indicates a recording resolution of 320 × 240, and C indicates a recording resolution of 160 × 120. Further, assuming that the permissible circles of confusion necessary for realizing the recording resolution in each case are Ra, Rb, and Rc, respectively, the relationship of Rb = Ra × 2 and Rc = Ra × 4 is generally established.

  From this, the maximum size of the blur that seems to be in focus during the zoom operation is 2 times and 4 times in the case of B and C, respectively, compared to the case of A. That is, the smaller the recording resolution, the larger the allowable amount of blur.

  In other words, in the case of B, even if the blur is doubled compared to the case of A, it can be determined that the focus is in the same way as in the case of A. Even if it is out of focus, it can be determined that the image is in focus as in the case of A.

  FIG. 4 shows an example of switching timing of mutual driving of the zoom lens and the focus lens. 4A is a zoom lens driving state when A in Table 1, FIG. 4B is a focus lens driving state when A is the same, and FIG. 4C is A. This shows the driving state of the zoom lens and the focus lens in this case. This indicates that the zoom lens and the focus lens are driven four times during the zoom operation, and the operation ends at time T3.

  In the case of B in Table 1, since the permissible circle of confusion Rb is twice Ra, the driving state in which the total driving amount of the zoom lens and the focus lens is kept as it is and the number of switching of the mutual driving is halved. Even in the case (shown in FIG. 4D), it is possible to perform a zoom operation in a focused state as in the case of A.

  Similarly, in the case of C in Table 1, since the allowable confusion circle diameter Rc is four times Ra, the total drive amount of the zoom lens and the focus lens is kept as it is, and the number of switching between mutual drive is set to 1/4. Even in the driven state (shown in FIG. 4E), it is possible to perform a zoom operation in a focused state as in the case of A.

  Here, in the case of B and C, the total number of lens operation times is reduced because the number of drive switchings is reduced (respectively T4 and T5), and the time required for the zoom operation is reduced. Is possible.

  Therefore, by setting the switching timing of alternate driving of the zoom lens and focus lens according to the recording resolution during continuous shooting, it is possible to realize a smooth real-time image and a reduction in operating time. it can.

  Next, proceeding to step S7, the lens is driven to perform a zoom operation. Here, based on the frame rate information acquired in step S4 or the recording resolution information acquired in step S6, switching between mutual driving of the zoom lens and the focus lens is performed so that the zoom photographed image recorded in real time during the zoom operation does not feel strange. Set the timing and drive the lens.

  If it is detected in step S3 that still image shooting is performed by the detection means 12, the process proceeds to step S5. When the process proceeds to step S5, display resolution information of an image displayed in real time on the display unit is acquired. If the user arbitrarily sets the zoom speed, the zoom speed information is acquired.

  Here, a case where still image shooting is performed will be described.

  During still image shooting, since shooting and recording are not performed during zoom operation, setting the switching timing of the mutual drive of the zoom lens and focus lens according to the resolution of the display unit makes it easy to zoom without causing discomfort Operation is possible.

  In the case of still image shooting, the resolution of the display unit is largely lower than the recording resolution. For example, even when shooting at a resolution of 640 × 480, the display screen is displayed at a resolution of 160 × 120. There is.

  In such a case, the operator performs the zoom operation while confirming at a display resolution of 160 × 120 appearing on the display screen in real time. Even at the timing (that is, when the number of times of switching is small), it seems that the display unit is sufficiently focused.

  Therefore, by setting the switching timing of the mutual lens driving in accordance with the display resolution information obtained in step S5 in FIG. 2, it is possible to perform a quick zoom operation without a sense of incongruity.

  Here, at the time of still image shooting, it is only necessary to be in focus at the time of recording after the zoom operation is stopped, and it is not always necessary to be in focus during the zoom operation. Therefore, it is possible to arbitrarily set the switching timing of the alternate driving of the zoom lens and the focus lens during still image shooting.

  For example, during zoom operation, only the zoom lens is driven and the focus lens is not operated, or zoom operation is performed by controlling the lens drive so that the drive amount of the focus lens is so small that display resolution cannot be obtained. It can also be set to improve speed.

  In this case, since the operation speed can be arbitrarily set, the zoom speed can be prioritized over the smoothness of the image change.

  Next, proceeding to step S7, the lens is driven to perform a zoom operation. Here, based on the display resolution information of the shooting screen acquired in step S5, the switching timing of the mutual driving of the zoom lens and the focus lens is set so that the zoom image displayed in real time during the zoom operation does not feel strange. .

  In step S5, when the user has set the zoom speed, the switching timing may be set from the zoom speed.

  According to the present invention, even when a zoom operation is performed by switching and driving two or more motors during continuous shooting and still image shooting, the image changes smoothly and quickly so that the user does not feel uncomfortable. A zoom operation can be performed.

  In the present embodiment, the case where the switching timing of the mutual driving of the zoom lens and the focus lens is a constant cycle is shown, but the cycle of the switching timing is earlier at the end of driving than at the start of driving. The switching timing may be controlled.

  As shown in FIG. 5, for example, the switching cycle of the alternate lens driving is shortened stepwise from the start of driving, and the switching timing is set so that the cycle Tc at the end of driving is smaller than the cycle Ta at the start of driving. By controlling the zoom lens, the zoom lens can be driven larger at the start of driving, and an image with the desired zoom magnification can be quickly obtained.On the other hand, the focus lens is driven in a short period near the desired zoom magnification, thereby making the image more detailed. It is possible to focus accurately and to prevent image blurring during shooting more effectively.

  In FIG. 5, the switching cycle of the zoom lens and the focus lens is set so that the driving end time is earlier than the driving start time. However, only the zoom lens switching cycle is set to the driving end time from the driving start time. The same effect can be obtained even if it is set to be faster.

  Also, in this embodiment, for the sake of simplicity, the zoom lens and the focus lens operate in one direction during the zoom operation, and when the zoom lens is moved with the focus lens fixed, it is proportional to the moving distance. The case where the amount of blurring also becomes large is shown.

  The present invention is not limited to the above-described embodiment, and can be implemented in various modes obtained by changing the above-described embodiment without departing from the gist thereof.

  For example, when the amount of blur is not proportional to the moving distance of the zoom lens, or when the moving direction of the focus lens during the zoom operation is not one direction, the driving amount per time of the zoom lens and the focus lens is constant. In other words, a state where the number of times of driving and a driving amount change are generated. Even in such a case, the lens drive amount calculated from the recording resolution, the frame rate, the resolution of the display unit and the lens characteristics and the switching timing of the mutual drive are set in advance, and the above settings are made in step S7 in FIG. By driving the lens based on this, the image change is smooth and a quick zoom operation is possible.

  In the flowchart of FIG. 2, any one or more of steps S4, S5, and S6 can be omitted. Furthermore, the order of step S4 and step S6 may be interchanged. Even in such a case, by driving the lens based on the set switching timing in step S7, the image change is smooth and a quick zoom operation is possible.

  As described above, according to the lens driving device and the lens driving method of the present invention, the user feels uncomfortable even when zooming is performed by switching and driving two or more motors during continuous shooting and still image shooting. The image changes smoothly so that no zooming occurs, and a quick zoom operation can be performed.

  The present invention can be applied to a lens driving device and a lens driving method for a camera module.

It is a block diagram which shows the main structures of the lens drive device which is embodiment of this invention. It is a flowchart which shows the lens drive method which is embodiment of this invention. It is a figure which shows an example of the switching timing of the mutual drive of a zoom lens and a focus lens. It is a figure which shows an example of the switching timing of the mutual drive of a zoom lens and a focus lens. It is a figure which shows an example of the switching timing of the mutual drive of a zoom lens and a focus lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control part 11 Shooting mode start means 12 Detection means 13 1st control means 14 2nd control means 15 Zoom lens 16 Focus lens 17 Shooting type setting means

Claims (10)

In the lens driving device of the camera module,
A zoom lens,
A focus lens,
First driving means and second driving means for driving the zoom lens and the focus lens, respectively;
A detecting means for detecting a photographing type;
A lens driving apparatus comprising: a control unit that changes a switching timing of alternate driving of the zoom lens and the focus lens based on a detection result by the detection unit. In the lens driving device of the camera module,
2. The lens driving device according to claim 1, wherein the detecting means is means for detecting whether the photographing by the camera module is continuous photographing or still image photographing. In the lens driving device of the camera module,
Detecting whether shooting by the camera module is continuous shooting or still image shooting,
3. The switching timing of alternate driving of the zoom lens and the focus lens is controlled so that the switching timing in the case of continuous shooting is earlier than the switching timing in the case of still image shooting. The lens driving device according to any one of the above. In the lens driving device of the camera module,
4. The switching timing is controlled so that at least the switching period of the alternate driving of the zoom lens is earlier at the end of driving than at the start of driving. 5. Lens drive device. In the lens driving device of the camera module,
5. The lens driving device according to claim 1, wherein the number of times of switching the alternate driving of the zoom lens and the focus lens is controlled according to a photographing type. In the lens driving device of the camera module,
6. The lens driving device according to claim 1, wherein the switching timing of the alternate driving of the zoom lens and the focus lens is set according to the recording resolution during continuous shooting. In the lens driving device of the camera module,
7. The lens driving device according to claim 1, wherein a switching timing for alternately driving the zoom lens and the focus lens is set in accordance with a frame rate during continuous shooting. In the lens driving device of the camera module,
8. The lens driving device according to claim 1, wherein the switching timing of the alternate driving of the zoom lens and the focus lens is set according to the resolution of the display unit at the time of still image shooting. In the lens driving device of the camera module,
The lens driving device according to any one of claims 1 to 8, wherein a switching timing for alternately driving the zoom lens and the focus lens is arbitrarily set during still image shooting. A lens driving method comprising driving a lens using the lens driving device according to claim 1.

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