JP2011064889A - Camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce imaging waiting time to the utmost by eliminating excessive calibration operation by a position detection means. <P>SOLUTION: Current ambient temperature T is compared with ambient temperature Ta (stored value) of a camera before shipping. If a temperature difference between them is over a predetermined value ΔT, regular calibration operation is performed. If the temperature difference is within the predetermined value ΔT, whether elapsed time t starting with a predetermined point of time when manufacturing the camera exceeds a predetermined time ta is determined. If the time t exceeds the time ta, the regular calibration operation is performed, and if the time t does not exceed the time ta, simple calibration operation is performed. The simple calibration operation is completed in a shorter time than the regular calibration operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a camera system having an image blur correction function.

  A camera capable of optically correcting image shake caused by camera shake or the like is known. This type of camera has a shake detection unit that detects camera shake and a shake correction lens that is movable in a direction orthogonal to the photographing optical axis, and drives the shake correction lens based on the output of the shake detection unit. Thus, the shake of the image on the imaging plane is corrected. In order to perform highly accurate shake correction, it is necessary to always grasp the accurate position of the correction lens in real time, and for this purpose, a position detection device using a Hall element or the like is provided. However, there may be a gap between the output of the position detection device and the actual correction lens position due to the environment temperature of the camera and changes over time. Is essential. Therefore, there is a camera that can always perform highly accurate shake correction control by performing a calibration operation of the position detection device each time the camera is turned on (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-80547

  The calibration operation of the position detection device is important for improving the accuracy of shake correction control, but excessive calibration operation is not preferable because it only increases the waiting time for photographing. The cited document 1 does not consider this point.

  The present invention relates to a shake correction member that is driven in a direction crossing the imaging optical axis, a position detection unit that detects the position of the shake correction member, a shake detection unit that detects a shake amount of a camera or a lens barrel, and a shake A digital camera system including shake correction control means for performing shake correction control for driving a shake correction member to correct image shake caused by camera or lens barrel shake based on detection results of the detection means and the position detection means Before the shake correction control, a normal calibration operation for adjusting a plurality of predetermined items with respect to the position detecting means and a simple calibration operation for performing only a part of the plurality of adjustments are performed. It is characterized by comprising calibration means for performing any one of the above and calibration control means for determining whether a normal calibration operation or a simple calibration operation is performed according to conditions.

  According to the present invention, it is possible to eliminate the excessive calibration operation of the position detection means and shorten the photographing waiting time as much as possible.

The control block diagram of the digital camera in one Embodiment of this invention. The block diagram which shows the detail of a shake correction mechanism. The figure explaining the drive range of a correction lens. The figure explaining the outline | summary of the calibration operation | movement of a position detection part. The figure which shows the example of a procedure of a full-scale (normal) calibration operation | movement. The figure which shows the example of a procedure of simple calibration operation | movement. The flowchart which shows the procedure of calibration control. The flowchart which shows the other example of a procedure of calibration control. The figure which shows the other example of a procedure of simple calibration operation | movement.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram of a digital camera according to the present embodiment. The camera 1 includes a photographic lens 2, an image sensor 3, a correction lens driving unit 4, a correction lens position detection unit 5, a Yaw direction shake detection element 6, a Pitch direction shake detection element 7, a control unit 8, The actuator drive unit 9, the aperture drive unit 10, the focus drive unit 11, the operation unit 12, the image processing unit 13, the liquid crystal monitor 14, and the temperature sensor 16 are provided.

  The subject luminous flux that has passed through the photographic lens 2 is imaged by the imaging device 3, and the imaging signal is input to the image processing unit 13. The image processing unit 13 includes an image processing circuit, a display circuit, a recording / reproducing circuit, and the like. The image processing circuit performs various processes on the input imaging signal to generate image data. The image data is displayed on a liquid crystal monitor 14 provided on the back of the camera or the like through processing by a display circuit.

  When the shooting mode is set, the above imaging is repeated, and so-called through image display (live view display) is performed in which images based on the obtained image data are sequentially updated and displayed on the liquid crystal monitor 14. The photographer can determine the composition while viewing the live view display. When a release operation is performed, imaging is performed again, and the generated image data is recorded on a recording medium 15 such as a memory card by a recording / reproducing circuit as an image file that can be handled by a computer. In the reproduction mode, the image data recorded on the recording medium 15 can be read out by the recording / reproducing circuit and displayed on the liquid crystal monitor 14 through processing by the image processing circuit and the display circuit.

  The control unit 8 includes a CPU, a memory, and other peripheral circuits. The control unit 8 controls the image processing unit 13 and the actuator driving unit 9 and performs shake correction control described later. The actuator driving unit 9 drives the diaphragm through the diaphragm driving unit 10 and performs focus adjustment (focusing) through the focus driving unit 11. The operation unit 12 includes a power button, a release button, various operation members used for reproduction operation, information input, and the like.

Next, shake correction control in this embodiment will be described.
The photographic lens 2 includes a correction lens 2a for correcting image blur caused by camera shake or the like, and the correction lens 2a is driven in a direction intersecting the optical axis by the correction lens driving unit 4 to thereby detect the imaging element 3 The image formation position of the subject image on is corrected. The correction lens position detection unit 5 detects the position of the correction lens 2a.

FIG. 2 shows a specific configuration example of the correction lens 2a, the correction lens driving unit 4, and the correction lens position detection unit 5.
The correction lens 2a is held by the lens frame 2b and can be moved together with the lens frame 2b in a direction crossing the photographing optical axis. The moving range is mechanically limited by the movable limit frame 2c. The correction lens driving unit 4 includes a voice coil motor (VCM), and includes a driving magnet 4a, a driving magnet yoke 4b, a coil 4c, and a coil yoke 4d. The drive magnet 4a and the drive magnet yoke 4b are integrated and fixed to the movable limit frame 2c, and the coil yoke 4d is also fixed to the movable limit frame 2c. The coil 4c is fixed to the lens frame 2b and is disposed so as to be sandwiched between the driving magnet 4a and the coil yoke 4d. When the coil 4c is energized via the controller 8, the correction lens 2a moves in the direction intersecting the optical axis within the movable limit frame 2c.

  The correction lens position detection unit 5 includes a position detection magnet 5a, a position detection yoke 5b, and a hall element 5c. The position detection magnet 5a and the position detection yoke 5b are integrated and fixed to the lens frame 2b, and the Hall element 5c is fixed to the movable restriction frame 2c. The correction lens position detection unit 5 outputs the output voltage from the Hall element 5c to the control unit 8, and the control unit 8 corrects based on the output voltage value (position detection signal) from the correction lens position detection unit 5. The position of the lens 2a is detected.

  In FIG. 1, a Yaw direction shake detection element 6 is a gyro sensor for detecting yawing of the main body of the camera 1, that is, lateral shake. The pitch direction shake detection element 7 is a gyro sensor for detecting pitching of the main body of the camera 1, that is, vertical direction shake. The Yaw direction shake detection element 6 and the Pitch direction shake detection element 7 output the respective detection results to the control unit 8. Based on the outputs from the Yaw direction shake detection element 6 and the Pitch direction shake detection element 7 and the detection output of the position detection unit 5, the control unit 8 drives and controls the correction lens 2 a so as to cancel the shake.

  FIG. 3 is a diagram showing a driving range of the correction lens 2a. The correction lens 2a is allowed to move within the mechanical drive range surrounded by the drive restriction frame 2c, but in actual shake correction control, a narrower range (soft drive range) AR centered on the center of the mechanical drive range. Driven in. Therefore, the correction lens 2a does not collide with the drive restriction frame 2c during shake correction control.

  Note that this embodiment assumes a camera having a photographic lens fixedly. However, when applied to a camera with interchangeable lenses, the correction lens 2a, the correction lens drive unit 4, and the correction lens position detection unit 5 are used. The shake detection elements 6 and 7 are provided on the interchangeable lens side.

By the way, in a camera that performs such shake correction control, the lens position detector 5 is calibrated before shipping the product in order to enable highly accurate position detection. At the time of the calibration operation, for example, as shown in FIG. 4A, the correction lens 2a is applied to the opposing mechanical limit (movable limit frame) 2c, and the position detection signals in the applied state are V1, V2 (FIG. Adjustments are made so that b)). -L1 and L1 are lens positions when the correction lens 2a is subjected to both mechanical limitations, 51 is an ideal position detection output straight line to be realized by calibration, and 52 is a non-ideal same output straight line before calibration. An example is shown respectively.
4 shows an example of adjustment in the horizontal direction, the same adjustment is performed in the vertical direction.

A specific procedure of the calibration operation is shown in FIG.
First, the correction lens 2a is driven to hit one of the horizontal mechanical limits, and the offset voltage adjustment signal Vh_offset is adjusted so that the position detection signal at that time becomes V1 (first adjustment). Next, the correction lens 2a is placed on the other mechanical limit in the horizontal direction and adjusted so that the position detection signal at that time becomes V2 (second adjustment). The second adjustment is performed by adjusting the Hall element drive current Vhi to adjust the gain, that is, the slope of the output straight line, and adjusting the offset level by adjusting the offset voltage adjustment signal. The adjustment value obtained in each adjustment is stored in a nonvolatile memory. Next, the correction lens 2a is again applied to one mechanical limit, and a soft adjustment is performed (third adjustment). This is a process of storing an error between the position detection signal and V1 when the mechanical restriction is again applied as a correction value. When the shake correction control is actually performed, highly accurate position detection can be performed by using a value obtained by correcting the obtained position detection signal with the correction value.
The same process is performed in the vertical direction.

  By using each of the stored adjustment values, the dynamic range can be used effectively while preventing saturation of the position detection signal, accurate position detection is possible, and high-precision shake correction control can be performed. .

  However, the Hall element 5c constituting the position detection unit 5 is easily affected by temperature, and also has output fluctuation due to secular change. Depending on the situation, highly accurate position detection (shake correction) can be performed even using an adjustment value at the time of shipment. Cannot be expected. Therefore, every time the camera is turned on after shipment, the control unit 8 performs a calibration operation of the position detection unit 5 and performs subsequent shake correction control based on the adjustment value obtained each time.

  However, in the situation where the ambient temperature when using the camera is close to the temperature at the time of calibration before shipment and is not yet affected by the secular change, the full-scale calibration operation as shown in FIG. 5 is unnecessary and simpler. Sufficient position detection accuracy can be obtained by a typical calibration operation. Performing a full-scale calibration operation in such a situation is not preferable because it simply increases the start-up time of the camera (the time from when the power is turned on to when shooting is possible). Therefore, in this embodiment, the calibration operation method is changed according to the situation.

  FIG. 6 shows an example of a simple calibration operation. In this example, the correction lens 2a is driven to be subjected to one mechanical limit in the horizontal direction, the offset voltage adjustment signal Vh_offset is adjusted so that the position detection signal at that time becomes V1, and then the correction lens 2a is moved in the horizontal direction. The other mechanical restriction is applied, and software adjustment is made for V2, and the process ends. Each adjustment value is stored in a memory. The gain (slope) adjustment as shown in FIG. 5 is not performed, and at the time of shake correction control, the offset level adjustment value and the software adjustment value obtained by the calibration operation, and the gain obtained by the calibration operation before shipment. Adjustment values are used.

  In the calibration (adjustment) operation of FIG. 6, since the gain is not adjusted, the resolution of the position detection signal decreases when the gain is low, and conversely, the position detection signal may be saturated when the gain increases. Further, the relationship between the mechanical limit and the soft limit is partially reversed, and the correction lens 2a may collide with the mechanical limit as it is. In such a case, the collision itself can be avoided by narrowing the soft limit more than usual, but if the range is narrowed, deterioration of the shake correction performance is inevitable. However, in the situation where the temperature when using the camera is almost the same as the temperature at the time of calibration before shipment and there is no change over time, even if the gain adjustment value before shipment is used, the above-mentioned decrease in resolution or signal saturation occurs. There is a high possibility that inconvenience such as the collision of the correction lens 2a does not occur. That is, if only simple adjustment as shown in FIG. 6 is performed, there is a high possibility that satisfactory shake correction performance can be obtained without narrowing the drive range of the correction lens 2a. Since the simple calibration operation requires a shorter time than the full-scale calibration operation, the camera start-up time can be shortened accordingly.

Next, with reference to the flowchart of FIG. 7, the proper use of the full-scale calibration operation and the simple calibration operation will be described.
The control unit 8 initializes each unit in accordance with the power-on operation of the camera, and performs calibration processing of the position detection unit 5 shown in FIG. First, in step S1, the output of the temperature sensor 16 is read to obtain the current camera ambient temperature T. In step S2, the current ambient temperature T is compared with the same temperature Ta (memory value) at the time of configuration before shipment, and if the difference exceeds a predetermined value ΔT (for example, 15 degrees), full-scale calibration is performed. It is determined that an operation is necessary, and the process proceeds to step S3. In step S3, a full-scale calibration operation as described in FIG. 5 is performed.

  On the other hand, if the temperature difference is within the predetermined value ΔT, the process proceeds to step S4, and it is determined whether or not the elapsed time t starting from the predetermined time point when the camera is manufactured exceeds the predetermined time ta. This elapsed time t can be obtained using a clock built in the camera. If step S4 is affirmed, it is determined that the deviation of the output of the position detector 5 due to secular change is so large that it cannot be ignored, a full-scale calibration operation is performed in step S5, and then the value of ta is updated in step S6.

  For example, ta is updated by adding a numerical value Δt to the elapsed time t each time the calibration operation is performed at 4 in step S, for example. In view of the fact that the influence due to secular change becomes conspicuous with the passage of time, it is desirable to gradually reduce the added numerical value Δt.

  If step S4 is denied, it is determined that there is no influence due to secular change, and since the difference between the ambient temperatures T and Ta is small, a simple calibration operation as described in FIG. 6 is performed in step S7. After steps S3, S6, and S7, the process returns to the main process (not shown) and photographing is allowed.

FIG. 8 shows a flow in another embodiment, which is different from FIG.
The control unit 8 initializes each unit in accordance with the power-on operation of the camera, and performs calibration processing of the position detection unit 5 shown in FIG. In step S11, it is determined whether the flag is on or off. This flag determines whether or not to perform a full-scale calibration operation to cope with the secular change, and is set to off when the camera is shipped.

  If the flag is off, the process proceeds to step S12, and the camera ambient temperature T is read from the temperature sensor 16 in the same manner as described above, and the ambient temperature T is compared with the same temperature Ta (stored value) at the time of configuration before shipment in step S13. . If the temperature difference exceeds a predetermined value ΔT (for example, 15 degrees), a full-scale calibration operation is performed in step S14, and if it is within the predetermined value ΔT, a simple calibration operation is performed in step S15.

  In step S16, the adjustment value obtained in the calibration operation in step S15 is compared with the adjustment value (stored value) obtained in the calibration operation before shipment. If the difference is less than the predetermined value, the flag is set in step S17. Turn off and return. On the other hand, if the difference between the adjustment values exceeds the predetermined value, the flag is turned on in step S18 and the process returns. That is, when the temperature difference ΔT is within a predetermined value, the adjustment value is greatly different. Therefore, it is determined that a deviation has occurred due to some factor other than temperature (aging), and next time full-scale calibration operation is performed. Turn on the flag to do. When the power is turned on next time, since the flag is on, a full-scale calibration operation is performed unconditionally regardless of the temperature (steps S11 → S14).

  FIG. 9 shows another example of a simple calibration operation. This is simpler than the calibration operation shown in FIG. 6, and the level of the position detection signal is confirmed by applying the correction lens 2a to one mechanical restriction, and then the software adjustment is applied to the other mechanical restriction. To finish. The software adjustment value is stored in the memory as used for shake correction control. In this case, substantially only soft adjustment is performed, and neither gain adjustment nor offset level adjustment is performed. During shake correction control, the gain adjustment value and the offset level adjustment value obtained by the calibration operation before shipment are used. However, in a situation where the temperature at the time of camera use is almost the same as the temperature at the time of calibration before shipment and there is no change over time, the gain adjustment value and offset level adjustment value before shipment are not as high as the calibration operation of FIG. Even if is used, there is a high possibility that satisfactory shake correction performance can be obtained. The simple calibration operation shown in FIG. 9 can be performed in a shorter time than the calibration operation shown in FIG. 6, and the startup time of the camera can be further shortened.

  Which of the calibration operations of FIGS. 6 and 9 is adopted as a simple calibration operation may be determined depending on which of the start-up time and the shake correction performance is important. Alternatively, when performing a simple calibration operation (for example, step S7 in FIG. 7 or step S15 in FIG. 8), the temperature difference (| T−Ta |) exceeds the first predetermined value ΔT1 (<ΔT). If the calibration operation of FIG. 6 is less than ΔT1, the calibration operation of FIG. 9 may be performed.

  For example, when a position detection unit that hardly changes over time is used, the calibration operation may be selectively used only by the temperature difference. For example, when applied to the example of FIG. 7, steps S4 to S6 are deleted, and when step S2 is denied, the flow proceeds to step S7. On the contrary, when a position detection unit in which the temperature difference does not cause a problem is used, the calibration operation may be properly used only by secular change. In this case, steps S2 and S3 are deleted, and the flow proceeds from step S1 to step S4.

  In the above, an example in which the correction lens constituting the photographing optical system is driven to perform image blur correction has been described. However, the present invention can also be applied to a camera that drives an image sensor to perform image blur correction.

DESCRIPTION OF SYMBOLS 1 Camera, 2 Shooting lens, 2a Correction lens, 2b Lens frame, 2c Movable restriction frame, 3 Imaging element, 4 Correction lens drive part, 4a Drive magnet, 4b Drive magnet yoke, 4c coil, 4d Coil yoke, 5 Correction lens position detector 5a
Position detection magnet, 5b Position detection yoke, 5c Hall element, 6 Yaw direction shake detection element, 7 Pitch direction shake detection element, 8 Control section, 9 Actuator drive section, 10 Aperture drive section, 11 Focus drive section, 12 operation Part, 13 image processing part, 14 liquid crystal monitor, 15 recording medium, 16 temperature sensor

Claims (7)

A shake correction member driven in a direction intersecting the imaging optical axis;
Position detecting means for detecting the position of the shake correction member;
Shake detection means for detecting the shake amount of the camera or lens barrel;
And a shake correction control means for performing shake correction control for driving the shake correction member to correct image shake caused by shake of the camera or the lens barrel based on the detection results of the shake detection means and the position detection means. In the digital camera system
Prior to the shake correction control, either a normal calibration operation for adjusting a plurality of predetermined items with respect to the position detecting means or a simple calibration operation for performing only a part of the plurality of items for adjustment. Calibration means for
A camera system comprising calibration control means for determining whether to perform the normal calibration operation or the simple calibration operation according to a condition.   The calibration control means performs the normal calibration operation when an elapsed time from a predetermined time before camera shipment exceeds a predetermined time, and performs the simple calibration operation when the elapsed time does not exceed the predetermined time. The camera system according to claim 1.   The calibration control means performs the normal calibration operation when the difference between the current temperature and the temperature when the calibration operation has been performed in the past exceeds a predetermined value, and the simple calibration operation when the difference does not exceed the predetermined value. The camera system according to claim 1, wherein:   When the difference between the current temperature and the temperature when the calibration operation was performed in the past is less than a predetermined value and the elapsed time from the predetermined time before camera shipment does not exceed the predetermined time, the calibration control means The camera system according to claim 1, wherein the simple calibration operation is performed, and a normal calibration operation is performed in other cases.   The calibration control unit performs the normal calibration operation when it is determined that the output fluctuation due to aging of the position detection unit exceeds a predetermined value, and performs the simple calibration operation when it is determined that the output variation does not exceed the predetermined value. The camera system according to claim 1, wherein the camera system is performed.   The calibration control means includes a calibration result of the normal or simple calibration operation performed in the past and a calibration result of the normal or simple calibration operation performed under the same temperature condition as the past calibration operation. 6. The camera system according to claim 5, wherein when the difference is equal to or greater than a predetermined value, it is determined that output fluctuation due to secular change exceeds a predetermined value.   When the normal calibration operation is performed, the shake correction control unit performs the shake correction control using the adjustment results of the plurality of items obtained by the calibration operation, and performs the simple calibration operation. In the case where the adjustment is performed, the shake correction control is performed using the adjustment results of some adjustment items obtained in the calibration operation and the adjustment results of other adjustment items obtained in the past calibration operation. The camera system according to any one of claims 1 to 6.

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