JP5526729B2 - Digital camera - Google Patents

Description

  The present invention relates to a digital camera having a camera shake correction function.

In recent years, many digital cameras include a camera shake correction device that reduces image blur due to camera shake, that is, an image stabilization control device. Since digital cameras have many functions in addition to the camera shake correction function, the camera power supply must supply a relatively large current when the camera shake correction device and other functional devices are activated simultaneously. Therefore, there is a problem that the size of the camera power supply device is increased.
In order to avoid this problem, there has been proposed a power supply control device that can restrict power supply to other functional devices when driving a camera shake correction device (see Patent Document 1).

JP 2000-10142 A

However, the power supply control device described in Patent Document 1 described above guarantees the priority of the operation of the camera shake correction device when the camera shake correction device and another function device are operated simultaneously, and supplies power to the other function devices. Therefore, depending on the shooting conditions, there arises a problem that power supply limitation to other functional devices causes a reduction in camera performance.
In particular, in recent digital cameras, the camera shake correction device operates during a still image capturing operation and also operates during the display of a live view image displayed on a monitor device, that is, a camera shake. The frequency at which the correction device and other functional devices operate simultaneously increases, and as a result, the above-described performance degradation becomes a problem that cannot be overlooked.

According to a first aspect of the present invention, there is provided a digital camera for imaging a subject image formed by a photographing optical system having a focus optical system driven by a first drive unit and a zoom optical system driven by a second drive unit. includes a device, a calculation means for calculating a correction amount of the camera shake, the drive motor, based on the correction amount calculated by said calculating means, and the shake correction mechanism for correcting the camera shake by the driving force of the driving motor, the A power supply unit that supplies power to the first drive unit, the second drive unit, and the drive motor; and a power setting unit that sets a power supply amount to the drive motor by the power supply unit , The power setting means sets a power supply amount to the drive motor to a first power supply amount while the first drive unit drives the focus optical system, and the second drive unit sets the zoom to the zoom motor. Optical system During driving, and sets the electric power supplied to the drive motor to the second power supply amount smaller than the first power supply.
According to a second aspect of the present invention, there is provided a digital camera having a photographing optical system having a focus optical system and a zoom optical system, an image pickup device for picking up a subject image formed by the photographing optical system, and a calculating means for calculating a correction amount of camera shake. And a shake correction mechanism that corrects camera shake with the driving force of the drive motor based on the correction amount calculated by the calculation means, and a first drive unit that drives the focus optical system A second drive unit for driving the zoom optical system, power supply means for supplying power to the first drive unit, the second drive unit, and the drive motor, and power supplied to the drive motor Power setting means for setting the power, and the power setting means sets the power supplied to the drive motor to a first power supply amount while the first drive unit is driving the focus optical system. And, during the driving of the second driving unit the zoom optical system, and sets the power supplied to the drive motor to the second power supply amount smaller than the first power supply amount .

  According to the digital camera of the present invention, when the optical adjustment unit adjusts the photographing optical system in the shooting preparation stage, the limiting unit limits the power supplied to the drive motor of the shake correction mechanism. Therefore, even if the performance of the shake correction mechanism is deteriorated, no problem is caused, and the enlargement of the power supply means can be avoided.

It is a block diagram which shows the structure of the digital camera which concerns on embodiment of this invention. It is a flowchart which shows the preparatory operation | movement of a shake correction optical system drive. 6 is a flowchart illustrating an operation for setting a driving condition of a shake correction optical system during zoom driving. 6 is a flowchart illustrating an operation for setting a drive condition of a shake correction optical system during focus drive. It is a flowchart which shows the operation | movement which sets the drive condition of a shake correction optical system at the time of aperture_diaphragm | restriction drive. 6 is a flowchart illustrating an operation for setting a driving condition of a shake correction optical system during shutter driving. FIG. 7A is a graph for explaining the duty ratio of pulse power. FIG. 7A shows a duty ratio of 60%, FIG. 7B shows a duty ratio of 70%, and FIG. 7C shows a duty ratio of 90%.

Hereinafter, a digital camera according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the digital camera 100 includes a zoom optical system 11, a focus optical system 12, a diaphragm 13, a shutter 14, a shake correction optical system 15, a gyro sensor 16, and an image sensor 17. The digital camera 100 also includes a zoom drive unit 21, a focusing drive unit 22, an aperture drive unit 23, a shutter drive unit 24, a shake correction drive unit 25, and a signal processing unit 26. The digital camera 100 further includes a CPU 30, an image signal processing circuit 31, an operation member 32, a storage medium 33, a system memory 34, a display device 35, a strobe device 36, a power conversion unit 40, and a battery 41.

  The zoom optical system 11, the focus optical system 12, the diaphragm 13, and the shake correction optical system 15 are included in the photographing optical system. The zoom optical system 11 is an optical system for changing the focal length of the photographing optical system, and the focus optical system 12 is an optical system for adjusting the focal position of the photographing optical system in accordance with the photographing distance to the subject. The diaphragm 13 is a member for adjusting the amount of incident light of the subject light. The shake correction optical system 15 is an optical system for correcting shake of the subject image on the imaging surface of the image sensor 17, and realizes an anti-vibration effect by driving eccentrically in a direction perpendicular to the optical axis of the subject light. To do.

The zoom optical system 11, the focus optical system 12, the aperture 13, the shutter 14, and the shake correction optical system 15 are respectively provided by a zoom drive unit 21, a focusing drive unit 22, an aperture drive unit 23, a shutter drive unit 24, and a shake correction drive unit 25. Driven. These zoom drive unit 21, focusing drive unit 22, aperture drive unit 23, shutter drive unit 24, and shake correction drive unit 25 each have a motor fed from the power conversion unit 40. In particular, a voice coil motor is used as the motor of the shake correction drive unit 25.
The shutter 14 is normally opened to generate a through image, and is closed at the end of photographing of a still image to finish the exposure of the image sensor 17.

The gyro sensor 16 detects a shake of the photographing optical system and outputs a shake signal (acceleration signal). The signal processing unit 26 calculates an image shake correction amount based on the shake signal.
The image sensor 13 generates an image signal by photoelectrically converting subject light from the photographing optical system.

  The CPU 30 inputs a signal output from each block to detect predetermined information or performs a predetermined calculation and outputs a control signal based on the calculation result to each block. That is, the CPU 30 comprehensively controls operations performed by the digital camera 100 by executing a program stored in the system memory 34.

  The image signal processing circuit 31 is configured as an ASIC, for example, and performs image processing based on an image signal input from the image sensor 17. The image processing includes, for example, contour enhancement, color temperature adjustment (white balance adjustment) processing, and format conversion processing for an image signal.

  The operation member 32 includes a power switch, that is, a power switch, a release switch, a menu switch, a plurality of operation buttons for operating a selection switch for the zoom operation mode and the autofocus operation mode, and the like. As a result, power is turned on, and operation signals corresponding to each operation such as shooting of an object, mode switching, menu selection / decision are sent to the CPU 30.

  The storage medium 33 is, for example, a memory card with a built-in semiconductor memory, and is removably attached to a slot of a memory card interface (not shown). By mounting the storage medium 33, data is written to the storage medium 33 and data is read from the storage medium 33. For example, when the digital camera 100 is set to the shooting mode, the captured image data is stored as an image file in the storage medium 33, and when the playback mode is set, the stored image data is read out. The reproduced image based on the image data can be displayed on the display device 35.

The system memory 34 stores a program to be executed by the CPU 30. The system memory 34 is used as a work memory for the CPU 30.
The display device 35 displays a through image captured by the image sensor 17, that is, a live view image, a reproduced image read from the storage medium 33, and the like.
The strobe device 36 is a device that performs so-called flash photography (strobe photography) by irradiating a subject with flash light.

  The power conversion unit includes a DC / DC converter, and steps up and down the voltage of the battery 41 to various voltages to zoom the drive unit 21, the focusing drive unit 22, the aperture drive unit 23, the shutter drive unit 24, and the shake correction drive. Power is supplied to each part of the digital camera 100 including the part 25.

Here, the relationship among the drive powers of the zoom drive unit 21, the focusing drive unit 22, the aperture drive unit 23, and the shutter drive unit 24 in the present embodiment will be described.
Among the driving power of the zoom driving unit 21, the driving power of the focusing driving unit 22, the driving power of the aperture driving unit 23, and the driving power of the shutter driving unit 24, the driving power of the zoom driving unit 21 is the maximum, and the focusing driving unit 22 , The driving power of the diaphragm driving unit 23 and the driving power of the shutter driving unit 24 are almost the same, and the smallest of these.
Thus, the relationship among the drive power Pz of the zoom drive unit 21, the drive power Pf of the focusing drive unit 22, the drive power Pd of the aperture drive unit 23, and the drive power Ps of the shutter drive unit 24 is as follows. .
Pz>Pf> Pd = Ps

  The voice coil motor of the shake correction driving unit 25 is driven by the pulse driving power from the power conversion unit 40. The power conversion unit 40 supplies pulse drive power having various duty ratios to the voice coil motor of the shake correction drive unit 25.

The duty ratio of the pulse power will be described with reference to FIG. The vertical axis of the graph indicates power, and the horizontal axis indicates time.
The pulse drive energization is performed, for example, by repeating energization on and off of the motor of the shake correction drive unit 25 or energization on and short brake state. When the energization on time is T1, and the energization off or short brake time is T2, energization is repeatedly performed so that T = T1 + T2 is a constant time (T: energization cycle). In the present embodiment, the duty ratio D is defined as D = 100% × T1 / (T1 + T2). 7A shows a duty ratio of 60%, FIG. 7B shows a duty ratio of 70%, and FIG. 7C shows a duty ratio of 90%. Specifically, in the case of a 20 kHz pulse energization and a duty ratio D = 25% energization, of the energization period T = 50 μsec, T1 = 12.5 μsec is the energization on time, and T2 = 37.5 μsec is energization It is time to turn off or short brake.

  The shake correction drive unit 25 can increase the amount of movement of the correction lens of the shake correction optical system 15 when pulse drive power with a high duty ratio is supplied, and can cope with large camera shake correction. When pulse driving power having a low duty ratio is supplied, the movement amount of the correction lens of the shake correction optical system 15 becomes relatively small, so that the effect of shake correction becomes small.

At the time of shooting a still image, the shake correction drive unit 25 must maximize image stabilization performance to reduce image blur. At this time, the power conversion unit 40 causes the shake correction drive unit 25 to be 100%. Supply duty drive power.
Note that the power conversion unit 40 supplies power to the shutter driving unit 24 simultaneously with power supply to the shake correction driving unit 25 when the still image is captured.

Thus, at the time of shooting a still image, so shake correction driver 25 to 100% duty ratio of the driving power P ₁₀₀ driving power Ps to the shutter driving unit 24 at the same time is supplied is supplied, the power converter 40 The total power of (P ₁₀₀ + Ps) is output to the shake correction driving unit 25 and the shutter driving unit 24.

  On the other hand, a through image is displayed in the previous stage of the still image shooting operation, that is, the preparation stage of the shooting operation, and the zooming unit 21 performs the zooming operation by the zoom driving unit 21, the autofocusing operation by the focusing driving unit 22, and the aperture driving unit. A diaphragm control operation by the image stabilization control unit 23 is performed, and an image blur correction operation by the shake correction driving unit 25 is performed in order to reduce image blur of the through image.

Thus, in the preparation stage of the photographing operation, power supply to the shake correction drive unit 25 and power supply to the zoom drive unit 21 or power supply to the shake correction drive unit 25 and power supply to the focusing drive unit 22 are performed at the same time. The drive power Pz of the unit 21 and the drive power Pf of the focusing drive unit 22 are both larger than the drive power Ps of the shutter drive unit 24. Therefore, if the case of supplying the driving power P ₁₀₀ this also shake the preparatory stage of the shooting operation correction driver 25 to 100% duty ratio, the shake correction driving section 25 of the preparatory stage of the shooting operation and the zoom driving unit 21 And the total driving power becomes larger than the total driving power (P ₁₀₀ + Ps) during still image shooting. Similarly, the total driving power of the shake correction driving unit 25 and the focusing driving unit 22 becomes larger than the total driving power (P ₁₀₀ + Ps) at the time of still image shooting.

Therefore, it is possible to avoid such a situation that the total driving power of the shake correction driving unit 25 and other driving units in the preparation stage of the shooting operation becomes larger than the total driving power (P ₁₀₀ + Ps) at the time of still image shooting. Therefore, in the preparatory stage of the photographing operation, when the shake correction drive unit 25 is operated simultaneously with the zoom drive unit 21, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 is limited to 60%, for example. To do. Similarly, when the shake correction drive unit 25 is operated simultaneously with the focusing drive unit 22, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 is limited to, for example, 70%. Further, when the shake correction drive unit 25 is operated simultaneously with the aperture drive unit 23 and when the shake correction drive unit 25 is operated alone, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 is set to 90, for example. %.

An upper limit value with a duty ratio of 90% is referred to as a first upper limit value, an upper limit value with a duty ratio of 70% is referred to as a second upper limit value, and an upper limit value with a duty ratio of 60% is referred to as a third upper limit value.
The duty ratio 70% of the second upper limit value is determined based on the difference between the driving power Pf of the focusing driving unit 22 and the driving power Ps of the shutter driving unit 24.
Similarly, the duty ratio 60% of the third upper limit value is determined based on the difference between the drive power Pz of the zoom drive unit 21 and the drive power Ps of the shutter drive unit 24.

Further, the duty ratio 90% of the first upper limit value is determined as follows.
In other words, the resolution of the through image displayed on the display device 35 is significantly lower than that of the captured still image. For this reason, the duty ratio of the pulse driving power of the shake correction driving unit 25 is limited to 90%, for example. Even in the through image, however, it is hardly possible to visually recognize a decrease in the image stabilization performance. In this way, at the time of displaying a through image, even if the upper limit of the duty ratio is limited to 90% and the power consumption is reduced, the vibration-proof performance in the through image hardly deteriorates.

The drive power Pz of the zoom drive unit 21, the drive power Pf of the focusing drive unit 22, the drive power Pd of the aperture drive unit 23, the drive power Ps of the shutter drive unit 24, etc. Supply to each.
Further, the power conversion unit 40 also supplies pulse drive power of a predetermined duty ratio of the shake correction drive unit 25 according to a command from the CPU 30.

Next, the operation of the digital camera of this embodiment will be described.
In FIG. 2, when the power switch is turned on by operating the operation member 32 in step S101, the CPU 30 sets the duty ratio of the pulse drive power of the shake correction drive unit 25 to the first upper limit value (90%) in step S102. ). Thereafter, in step S103, the CPU 30 executes an initialization operation of the shake correcting optical system 15. This initialization operation is calibration of the position detection signal of the shake correction optical system 15, that is, level adjustment of the position detection signal.

In step S <b> 104, the CPU 30 causes the shake correction drive unit 25 to drive the shake correction optical system 15 with the first upper limit drive power, and performs a shake prevention operation.
In step S105, the CPU 30 sets the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 to the third upper limit (60%), and in step S106, the CPU 30 initializes the imaging optical system barrel. Perform the action. In this lens barrel initialization operation, initialization of the zoom operation by the zoom drive unit 21, initialization of the autofocus operation by the focusing drive unit 22, and the like are sequentially performed.

In step S107, the CPU 30 resets the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 to the first upper limit value (90%). Thereafter, in step S108, the CPU 30 causes the display device 35 to display a through image.
As described above, since the resolution of the through image displayed on the display device 35 is not so high, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 is limited to the first upper limit value (90%). However, the reduction in the image stabilization performance due to the reduction in the amount of camera shake correction does not substantially appear in the through image.

In FIG. 3, when the photographer operates the operation member 32 to turn on the zoom switch, the zoom drive unit 21 starts the zoom operation in step S201. At the same time, the CPU 30 performs pulse drive power of the shake correction drive unit 25 in step S202. Is set to the third upper limit value (60%).
When the third upper limit value is set, the image stabilization performance due to the reduction in camera shake correction amount is considerably reduced, but the through image of the display device 35 has a low resolution and the subject image is enlarged or reduced due to zooming. The photographer cannot see the deterioration of the vibration proof performance or hardly cares about it.
When the zoom operation ends in step S203, in step S204, the CPU 30 sets the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 to the first upper limit value (90%).

In FIG. 4, when the photographer operates the operation member 32 to turn on the autofocus switch, the focusing drive unit 22 starts the autofocus operation in step S301. At the same time, the CPU 30 performs the shake correction drive unit 25 in step S302. The upper limit of the duty ratio of the pulse driving power is set to the second upper limit (70%).
When the second upper limit value is set, the image stabilization performance due to the reduction in the amount of camera shake correction is reduced, but the through image of the display device 35 has a low resolution and the image is blurred before focusing. Cannot see the decrease in the vibration proof performance or hardly care about it.
When the focusing operation is finished in step S303, in step S304, the CPU 30 sets the upper limit of the duty ratio of the pulse driving power of the shake correction driving unit 25 to the first upper limit value (90%).

In FIG. 5, at the same time as the diaphragm drive unit 23 starts driving the diaphragm 13 in step S401, the CPU 30 sets the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 to the first upper limit value (90) in step S402. %). This is because the driving power of the aperture driving unit 23 is substantially the same as the driving power of the shutter driving unit 24.
Even if the diaphragm drive is finished in step S403, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 remains the first upper limit value (90%) in step S404.

In FIG. 6, when the operation member 32 is operated in step S501 to turn on the release switch, in step S502, the CPU 30 sets the upper limit of the duty ratio of the drive power of the correction drive unit 25 to the first upper limit value (90%). Set. Here, the shake correction drive unit 25 may exhibit the maximum anti-vibration performance by feeding the drive power with a duty ratio of 100%.
Thereafter, a still image shooting operation is executed in step S503. In step S504, the shutter driving unit 24 opens and closes the shutter 14, and the exposure of the image sensor 17 is finished. When detecting the end of the shutter closing drive in step S505, the CPU 30 maintains the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 at the first upper limit value (90%) in step S506, Prepare for display of subsequent through images.

According to the digital camera 100 of the above-described embodiment, the through image is displayed on the display device 35 in the preparation stage of the photographing operation, and the resolution of the through image is relatively low. The upper limit of the duty ratio of 25 pulse drive power is limited to the first upper limit value. Further, when the focusing drive unit 22 and the zoom drive unit 21 are driven, the upper limit of the duty ratio of the pulse drive power of the shake correction drive unit 25 is limited to the second upper limit value and the third upper limit value, respectively.
In this way, the pulse drive power of the shake correction drive unit 25 can be limited to suppress an increase in the size of the power conversion unit 40, that is, an increase in mounting area, and to prevent battery consumption.
At this time, since the resolution of the through image is relatively low, the influence of the decrease in the image stabilization performance of the shake correction driving unit 25 is hardly visible. Further, when the through image is focused by the focusing drive unit 22 or the zoom drive unit 21 or when the zooming unit 21 is zoomed, it is impossible to visually recognize a further decrease in the image stabilization performance. Does not appear in the through image.

In this embodiment, the CPU 30 comprehensively controls the digital camera 100. However, the CPU 30 may include a plurality of CPUs, and one of them may control the image stabilization operation. For example, a dedicated CPU for anti-vibration operation control and another CPU for controlling the entire camera may be provided separately.
The present invention is not limited to the embodiment described above as long as the characteristics are not impaired.

11: Zoom optical system 12: Focus optical system 13: Aperture 14: Shutter 15: Shake correction optical system 17: Image sensor 21: Zoom drive unit 22: Focusing drive unit 23: Aperture drive unit 24: Shutter drive unit 25: Shake correction Drive unit 30: CPU
32: Operation member 35: Display device 40: Power conversion unit 41: Battery 100: Digital camera

Claims (5)

An image sensor that captures a subject image formed by a photographing optical system having a focus optical system driven by a first drive unit and a zoom optical system driven by a second drive unit ;
A calculation means for calculating a correction amount of camera shake;
A shake correction mechanism that includes a drive motor and corrects camera shake with the drive force of the drive motor based on the correction amount calculated by the calculation means;
Power supply means for supplying power to the first drive unit, the second drive unit, and the drive motor;
Power setting means for setting a power supply amount to the drive motor by the power supply means ,
The power setting means sets a power supply amount to the drive motor to a first power supply amount while the first drive unit drives the focus optical system, and the second drive unit sets the zoom to the zoom motor. A digital camera characterized in that, during driving of the optical system, the power supply amount to the drive motor is set to a second power supply amount that is smaller than the first power supply amount . A photographing optical system having a focus optical system and a zoom optical system;
An image sensor that captures a subject image formed by the imaging optical system;
A calculation means for calculating a correction amount of camera shake;
A shake correction mechanism that includes a drive motor and corrects camera shake with the drive force of the drive motor based on the correction amount calculated by the calculation means;
A first drive unit for driving the focus optical system;
A second drive unit for driving the zoom optical system;
Power supply means for supplying power to the first drive unit, the second drive unit, and the drive motor;
Power setting means for setting the power supplied to the drive motor,
The power setting means sets the power supplied to the drive motor to a first power supply amount while the first drive unit is driving the focus optical system, and the second drive unit sets the zoom. A digital camera characterized in that, during driving of the optical system, the power supplied to the drive motor is set to a second power supply amount that is smaller than the first power supply amount . The digital camera according to claim 1 or 2,
The drive motor is a voice coil motor;
The photographing optical system has a shake correction optical system,
The digital camera is characterized in that the shake correction mechanism corrects the camera shake by driving the shake correction optical system with a driving force of the voice coil motor. The digital camera according to claim 1 or 2,
The drive motor is a voice coil motor;
The digital camera according to claim 1, wherein the shake correction mechanism corrects the camera shake by driving the imaging device with a driving force of the voice coil motor. The digital camera according to claim 3 or 4,
The digital camera according to claim 1, wherein the power setting unit releases the restriction on power supply to the drive motor during an exposure time in which the image sensor is exposed in the recording image capturing stage.

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