JP2007094046A - Photographing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately control a fluidizing operation in accordance with a photographing mode when driving and controlling a correction optical member by reducing the frictional force by utilizing a fluidizing method, and to appropriately set shake correction characteristics in every photographing mode. <P>SOLUTION: Regarding the photographing apparatus with a shake correction function, including the correction optical member for compensating the shake, a shake detecting means for detecting the shake, a control means for adding/subtracting the specified amount of signal to/from a shake detection signal obtained by the shake detecting means in every specified cycle, and a shake correcting means for compensating the shake by driving the correction optical member by a driving means on the basis of the shake detection signal and the specified amount of the signal and displacing the optical axis of a photographing optical member, the photographing apparatus also includes a photographing mode selecting means for switching a moving image photographing mode and a still image photographing mode, and a control changing means for changing the specified amount in accordance with the selected photographing mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photographing apparatus capable of photographing both a still image and a moving image, and more particularly to a photographing apparatus with a so-called shake correction function.

  In recent years, there are many cameras that can shoot both still images and moving images, such as video cameras that can shoot still images and digital still cameras that can shoot moving images. In the future, it is conceivable that a single-lens reflex camera (or a single-lens reflex camera system) can also shoot moving images. Among these cameras, those having a so-called shake correction function for compensating (or correcting) shake are also known.

Here, a system for preventing camera shake in a single-lens reflex camera will be briefly described.
The camera shake at the time of shooting is usually 1 to 12 Hz as a frequency. Further, the vibration of the camera due to the shutter operation is usually in the range of ~ Hz. The camera shake correction function is capable of taking a photograph with no image blur even when the camera shakes due to such camera shake and shutter operation at the time of shutter release. As a basic idea for this purpose, it is necessary to detect the camera vibration due to the above-mentioned camera shake and displace the correction lens in accordance with the detected value. Therefore, in order to achieve that it is possible to take a photograph that does not cause image shake even if camera shake occurs, first, camera vibration is detected accurately, and second, light caused by camera shake due to camera shake and shutter operation. It is necessary to compensate for the axial displacement.

  The camera vibration is detected by a vibration detection means for detecting angular acceleration, angular velocity, angular displacement, etc. and a camera shake detection means for outputting the angular displacement by processing the output signal of the sensor electrically or mechanically. It can be done by mounting. Then, based on this detection information, a correction optical device that decenters the photographing optical axis is driven to suppress image blur.

  The example of FIG. 4 is a diagram of a system that suppresses image blur caused by the camera vertical shake 81p and the camera horizontal shake 81y in the direction of the arrow 81 shown in the figure. It is. In the figure, reference numeral 82 denotes a lens barrel, 83p and 83y denote shake detection means for detecting camera vertical shake vibration and camera horizontal shake vibration, respectively, and 84p and 84y indicate the respective vibration detection directions. Reference numeral 85 denotes a correction optical device, 86p and 86y denote coils for applying thrust to the correction optical device 85, and 87p and 87y denote position detection elements for detecting the position of the correction optical device 85. The correction optical device 85 is provided with a position control loop, and is driven with the outputs of the shake detection means 83p and 83y as target values to ensure stability on the image plane 88.

In the system for preventing camera shake in a single-lens reflex camera, as described above, it is necessary to cope with camera vibration due to shutter operation in addition to camera shake, so the mechanism for compensating the optical axis displacement described above requires high frequency response characteristics. Become. In order to improve the frequency characteristics of the mechanism for compensating for the optical axis displacement, it is necessary to reduce the friction on the contact surface of the correction optical device 85 described above. As a specific method for reducing this friction, Patent Document 1 discloses an example using a method called fluidizing. This fluidizing method applies the phenomenon that the dynamic friction force is smaller than the static friction force. By vibrating the part where the friction force is generated, the friction state is changed from static friction to dynamic friction. This is a reduction method. The greater the vibration amplitude and the higher the vibration frequency, the greater the effect of reducing the frictional force. If this method is applied to an image blur correction apparatus, the frictional force can be reduced and high frequency response characteristics can be obtained.
JP 2002-162661 A

By the way, when the above fluidizing method is used, minute vibrations are generated and sound is generated accordingly. When a single-lens reflex camera can shoot a moving image, the sound is recorded simultaneously with the shooting. When the above fluidizing method is used, a sound is generated, and this sound is recorded.
It is an object of the present invention to solve the above-mentioned problems in a technology for controlling driving by reducing frictional force using a fluidizing method for driving an optical element (correction lens or the like) for vibration isolation. To do. Specifically, in the case where still image shooting and moving image shooting are performed, an imaging device capable of performing an appropriate shake correction operation in each shooting by appropriately controlling the fluidizing operation. Is an issue.

  An imaging apparatus for solving the above-described problems includes a correction optical member for compensating (or correcting) a shake, and a shake detection unit that detects the shake. In addition, control means is provided for adding or subtracting a predetermined amount of signal for every predetermined period to the shake detection signal obtained by the shake detection means. Further, the image forming apparatus includes a shake correction unit that drives the correction optical member by a driving unit based on the shake detection signal and the predetermined amount of signal to displace the optical axis of the photographing optical member to compensate the shake. Furthermore, it has a photographing mode selecting means for switching between the moving picture photographing mode and the still image photographing mode, and a control changing means for changing the predetermined amount according to the photographing mode selection state.

  According to the present invention, when the correction optical member is driven and controlled by reducing the frictional force by using the fluidizing method, the fluidizing of the fluidizing fluid is changed according to the shooting mode (moving image shooting mode, still image shooting mode). Control the operation appropriately. Thereby, it is possible to obtain an appropriate shake correction operation characteristic in accordance with each photographing mode.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the illustrated examples.
FIG. 1 is a block diagram showing the configuration of a single-lens reflex camera according to the first embodiment of the present invention. This figure assumes that the image blur correction function is applied to an interchangeable lens of a single-lens reflex camera. An example of performing optimal fluidizing according to the shooting mode is shown.

  In FIG. 1, reference numeral 1 denotes a lens MPU, which controls the lens side by communication with the camera MPU 13. Reference numeral 2 denotes a shake sensor that detects a shake. The signal is cut, amplified, and noise-removed by the HPF / amplifier / LPF circuit 3 and input to the A / D conversion terminal of the lens MPU 1 as a shake signal. The Reference numeral 4 denotes a lens position detector that detects the position of the correction lens. The signal detected here is subjected to processing such as filtering by the signal processing circuit 5 and is applied to the A / D conversion input terminal of the lens MPU 1 as a position detection signal. Entered. The two shake signals and the position detection signal are subjected to feedback calculation by the lens MPU 1 and output as a correction lens drive signal via the coil driver 6, thereby performing image blur correction by the correction lens. . When image blur correction is not performed, the lens MPU 1 locks the correction lens via the motor driver 7, and when image blur correction is performed, the lens MPU 1 is unlocked (unlocked) via the motor driver 7. Note that the configuration is not directly related to the present invention, and therefore will be omitted.

In addition to the above-described image blur correction control, the lens MPU1 drives the focus lens and stops the aperture through motor drivers 9 and 10 based on the output of the position detector 8 that performs zoom / focus zone detection. Driving.
11 (ISSW) is an operation selection switch for performing image blur correction (Image Stabilizer), and 12 (A / MSW) is a switch for selecting auto focus or manual focus.
The lens MPU 1 performs camera / lens communication with the camera MPU 13, confirms the status (focal length, switch state, etc.) of the camera / lens, and transmits driving commands such as focus and aperture.

  Reference numeral 14 denotes a release switch, which is generally a two-stage stroke switch. The switch SW1 (not shown) is turned on by the first stroke of the release switch 14, and the release switch SW2 (not shown) is turned on by the second stroke. Reference numeral 15 denotes a shooting mode selection switch. For example, in the still image shooting mode, the focus lens is driven and the diaphragm is driven when SW1 = ON of the release switch 14, and a still image is recorded when SW2 = ON. In the moving image shooting mode, moving images are recorded with SW2 = ON.

Next, the operation of the main part of the lens MPU1 will be described with reference to the flowchart of FIG.
When the interchangeable lens is attached to the camera, serial communication is performed from the camera to the lens, and the lens MPU1 starts the operation from step # 1 in FIG.
First, in step # 1, initial settings for lens control and image blur correction control are performed. In the next step # 2, the states of the IS switch 11 and the A / M switch 12 are detected, and the position of the zoom / focus is detected via the position detector 8.
In the subsequent step # 3, it is determined whether or not there is a focus drive request communication from the camera. If there is a focus drive request, the process proceeds to step # 4, where the drive amount of the focus lens is commanded from the camera, and focus drive control is performed via the motor driver 9 accordingly. If there is no focus drive request in step # 3, the process proceeds to step # 5.

  In step # 5, the correction lens is locked and unlocked and the image blur correction start flag IS_START is set via the motor driver 7 in accordance with the communication from the camera and the state of the IS switch 11. Then, in the next step # 6, it is determined whether or not a command for stopping all driving (stopping all driving of the actuators in the lens) is received from the camera. If no operation is performed on the camera side, the full drive stop command is transmitted from the camera after a while. When this command is received, the process proceeds to step # 7, and full drive stop control is performed. In this all drive stop control, the drive of all actuators is stopped and the microcomputer is put into a sleep (stop) state. In addition, power supply to the image blur correction device (comprising a correction lens or the like) is also stopped.

Thereafter, when any operation is performed on the camera side, the camera MPU 13 communicates with the lens, and the lens MPU 1 cancels the sleep state by this communication.
During these operations, if there is a request for serial communication interruption or image blur correction control interruption due to communication from the camera, such interruption processing is performed.
In the serial communication interrupt processing, communication data is decoded, and lens processing such as aperture driving is performed according to the decoding result. Then, by decoding the communication data, it is possible to determine the ON state of the switch SW1, the ON state of the switch SW2, the shooting mode, the camera model, and the like.

  Further, the image blur correction interrupt is a timer interrupt that occurs every fixed period (for example, 500 μsec). Since the pitch direction (vertical direction) control and the yaw direction (lateral direction) control are alternately performed, the sampling period in one direction in this case is 1 msec. In addition, since there are many portions in which the control method is the same in both directions, only one system of the program is created. Even if the control method (calculation coefficient etc.) is the same, the result of the calculation is naturally different data in the pitch direction and the yaw direction. Therefore, the calculation is performed by setting a reference address for each of the pitch and yaw, specifying data such as calculation results as indirect addresses in the RAM, and switching the reference address between pitch control and yaw control.

When an image blur correction interruption occurs during the main operation of the camera, the lens MPU 1 starts control of image blur correction from step # 11 in FIG. Fluidizing control is performed in this image blur correction interrupt.
In FIG. 3, the lens MPU 1 first A / D converts the output of the angular velocity sensor which is the shake sensor 2 in step # 11. In the next step # 12, the state of the image blur correction start flag IS_START is checked. If the image blur correction start flag IS_START is cleared, the process proceeds to step # 13. Since image blur correction is not performed here, high pass and integral calculation are initialized. Then, the process proceeds to step # 24.

  On the other hand, if the image blur correction start flag IS_START is set in step # 12, the process proceeds to step # 14, and a high-pass filter operation is performed to operate the image blur correction. At this time, the time constant is switched for 2 to 3 seconds from the start of the image blur correction, and the rising image shake is also reduced. Then, in the next step # 15, integral calculation is performed. This result is angular displacement data θ. When panning is performed, the integration cutoff frequency is switched according to the deflection angular displacement.

  In the next step # 16, the decentering amount (sensitivity) of the correction lens with respect to the shake angle displacement changes depending on the zoom / focus position. Specifically, the zoom and focus positions are each divided into several zones, and the average optical image stabilization sensitivity (deg / mm) in each zone is read from the table data. Based on the read optical image stabilization sensitivity and the angular displacement data θ, it is converted into correction lens drive data. The calculation result is stored in a RAM area set by SFTDRV in the lens MPU1.

In the next step # 17, a fluidizing level (HFLVL) is set according to the shooting mode. When the amount of shake on the film surface by fluidizing is D, the focal length is f, and the optical image stabilization sensitivity is B,
D∝f × B × (HFLVL)
The relationship is established. That is, the shake amount D is proportional to “f × B × (HFLVL)”. Accordingly, if it is determined how much D is to be suppressed, the fluidizing level (HFLVL) can be set according to the focal length f and the optical image stabilization sensitivity B.

  For example, as in step # 16 above, the fluidizing level (HFLVL) corresponding to each zoom / focus position divided into several zones may be set by reading from the table data. Table data is provided for each photographing mode. When the shooting mode is the still image shooting mode, the optimum fluidizing level (HFLVL) derived from the focal length f and the optical image stabilization sensitivity B is calculated based on the shake amount D that does not affect the shooting result. Set to table data for shooting mode. When the shooting mode is the movie shooting mode, the optimum fluidizing level (HFLVL) derived from the focal length f and the optical image stabilization sensitivity B is calculated based on the shake amount D corresponding to the allowable sound level. Set to table data for shooting mode. As a result, in the case of the same focal length f and the same optical image stabilization sensitivity B, the moving image shooting mode fluidizing level is smaller than the still image shooting mode fluidizing level.

  In the next step # 18, it is determined whether or not the fluidizing set period has been reached. In order to perform fluidizing at a constant cycle, for example, if this interrupt is 500 μsec, the number of interrupts is counted, and when the count value reaches the set cycle value, the timing of fluidizing is determined. Can be set. If the fluidizing setting period has not been reached, the process proceeds to step # 19. Since the fluidizing timing has not been reached, the count value of the number of interruptions is incremented by one. Then, the process proceeds to step # 22. If the fluidizing setting period has been reached, the process proceeds to step # 20 to clear the fluidizing timing setting count value. In the next step # 21, the fluidizing control flag (HFFLG) is inverted, and the process proceeds to step # 22.

When the process proceeds to step # 22, the state of HFFLG is determined here. If HFFLG = 0, the process immediately proceeds to step # 24. On the other hand, if HFFLG = 1, the process proceeds to step # 23, HFLVL is added to SFTDRV, and the result is set as image blur correction drive data SFTDRV, and the process proceeds to step # 24.
In steps # 18 to # 23, since HFLVL is alternately added to SFTDRV (added / not added) at regular intervals, a signal with a constant cycle is superimposed on SFTDRV. In other words, fluidizing is performed at a certain period.

  In the next step # 24, the output of the lens position detector 4 (signal processing circuit 5) for detecting the position of the correction lens is A / D converted, and the A / D conversion result is set by SFTPST in the lens MPU1. Store in RAM area. Then, in the next step # 25, feedback calculation (SFTDRV-SFTPST) is performed, and in the subsequent step # 26, the loop gain is multiplied by the calculation result in step # 25. Then, in the next step # 27, a phase compensation calculation is performed in order to obtain a stable control system. Finally, in step # 28, the result in step # 27 is output to the microcomputer port as a PWM, and the interrupt is terminated. To do. The output is input to the coil driver 6, the correction lens is driven by the moving magnet, and the image blur is corrected.

In steps # 18 to # 23, the fluidizing level (HFLVL) is added (added / not added) to SFTDRV at regular intervals. However, the same effect can be obtained by alternately performing (subtracting / not subtracting) the fluidizing level (HFLVL).
As described above, in step # 17, the level of fluidizing is changed according to the shooting mode, so that an appropriate shake correction operation characteristic can be obtained according to each shooting mode.

In the above-described embodiment, the example in which the image blur prevention control is performed by digital control is shown, but analog control may be performed.
In addition, the image blur correction device is incorporated in the interchangeable lens. However, the image blur correction device may not be in the interchangeable lens but may be in the form of an accessory that enters the conversion lens attached in front of the interchangeable lens. .
In the above description, an example is shown in which an angular velocity sensor is used as the shake detection means. However, the shake detection means is any device that can detect shake, such as an angular acceleration sensor, an acceleration sensor, a speed sensor, an angular displacement sensor, a displacement sensor, and a method for detecting image shake itself. Also good.
In the above embodiment, the addition and subtraction of the fluidizing level (HFLVL) and the switching based on the photographing mode are performed by the lens MPU1, but these may be performed by the camera MPU13. Further, the IS switch 11 and the A / M switch 12 may be provided not on the interchangeable lens side but on the camera body side (side where the camera MPU 13 is disposed).

1 is a block diagram illustrating a configuration of a single-lens reflex camera with an image blur correction function according to an embodiment of the present invention. FIG. It is a flowchart which shows the main operation | movement of lens MPU in FIG. 2 is a flowchart showing an image blur correction control operation of a lens MPU in FIG. 1. It is a block diagram which shows an example of the image stabilization system of the conventional image blur correction apparatus.

Explanation of symbols

1: Lens MPU
2: shake sensor 4: position sensor 6: shake correction drive driver 15: shooting mode selection switch

Claims (4)

A correction optical member for correcting shake, a shake detection means for detecting the shake, and a control means for adding or subtracting a predetermined amount of signal to the shake detection signal obtained by the shake detection means for each predetermined period; In imaging, the image sensor includes: a shake correction unit that drives the correction optical member by a driving unit based on the shake detection signal and the predetermined amount of signal, and displaces an optical axis of the imaging optical member to compensate the shake. ,
An imaging apparatus comprising: a shooting mode selection unit that switches between a moving image shooting mode and a still image shooting mode; and a control change unit that changes the predetermined amount according to a shooting mode selection state.   2. The photographing apparatus according to claim 1, wherein the predetermined amount of the signal to be added or subtracted is smaller in value when the moving image shooting mode is selected than when the still image shooting mode is selected.   3. The camera main body and an interchangeable lens that can be attached to and detached from the camera main body, and at least the correction optical member and a part of the image shake correcting means are provided in the interchangeable lens. The imaging device described in 1.   The interchangeable lens according to claim 3.

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