JP2008065192A - Optical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical equipment that makes both reduction in power consumption and high speed correction of shaking compatible. <P>SOLUTION: A camera 100, having a pair of step motors 2 and 3 that moves the lens 1, includes switches 9 and 11 for changing the operation mode of the camera 100; drivers 4 and 5 for driving the step motors 2 and 3; and a microcomputer 6 for controlling the drivers 4 and 5 so that the drivers 4 and 5 simultaneously apply voltages to the step motors 2 and 3, when the switches 9 and 11 are in a first state; and the drivers 4 and 5 alternately apply voltages to the step motors 2 and 3 by time division, when the switches 9 and 11 are in a second state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generally relates to an optical apparatus, and more particularly to an optical apparatus having a plurality of step motors for driving optical elements. The present invention is suitable for a camera that performs shake correction by a pair of step motors, for example.

In recent years, there has been an increasing demand for digital cameras that can take high-quality images and can be used for a long time. 2. Description of the Related Art A camera shake correction mechanism that optically corrects camera shake in response to a request for high image quality photography is known. The camera shake correction mechanism drives the camera shake correction lens in a direction orthogonal to the optical axis in accordance with a signal from a shake detection unit such as a gyro, for example, and suppresses image shake on the imaging plane. For example, Patent Document 1 proposes that the correction lens is always driven during shake correction. Patent Documents 2 and 3 disclose a method of alternately driving a plurality of motors by time division.
JP-A-5-203895 JP-A-10-197779 JP 10-31593 A

  Although Patent Document 1 can realize high-speed camera shake correction, power consumption by the driving unit is large due to constant driving of the correction lens, and the request for long-time shooting cannot be satisfied. In particular, if the battery is downsized due to the downsizing of the digital camera and the capacity is reduced, the battery is consumed quickly. In addition, the driving means may become a noise source, and driving sound may be recorded during moving image shooting. On the other hand, Patent Documents 2 and 3 drive the correction lens driving means by time-division driving, so that power consumption can be reduced, but high-speed camera shake correction cannot be realized. As a result, Patent Documents 2 and 3 may not be able to capture a high-quality still image, for example.

  The present invention relates to an optical apparatus that achieves both reduction in power consumption and high-speed shake correction.

  An optical apparatus according to one aspect of the present invention is an optical apparatus having a plurality of step motors (for example, a pair of step motors) for moving an optical element (for example, a lens), and switching means for switching the operation of the optical apparatus. Driving means for driving the plurality of stepping motors; and when the switching means is in the first state, the driving means simultaneously applies a voltage to at least two of the plurality of stepping motors, and the switching means is the first And a control unit that controls the driving unit so that the driving unit alternately applies a voltage to the plurality of stepping motors in a time division manner in a second state different from the above state.

  A control method according to another aspect of the present invention includes a step of determining whether or not a state of a switching unit that switches an operation of an optical apparatus having a plurality of step motors that move an optical element is a first state, and the switching Determining whether the means is in a second state different from the first state; and if the switching means determines that the first state is present, at least two of the step motors A step of applying a voltage at the same time; and a step of alternately applying a voltage to the plurality of stepping motors in a time-sharing manner when the switching means determines that the state is the second state.

  According to the present invention, it is possible to provide an optical apparatus that achieves both reduction in power consumption and high-speed shake correction.

  Hereinafter, a digital camera 100 as an example of the optical apparatus of the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of the camera 100. In FIG. 1, reference numeral 1 denotes a shake correction lens, which is fixed so as to be movable in a direction orthogonal to the optical axis. Reference numeral 2 denotes a first step motor, which supports the shake correction lens 1 so as to be drivable in the first direction. Reference numeral 3 denotes a second step motor, which supports the shake correction lens 1 so as to be drivable in the second direction. In the present embodiment, the first direction and the second direction are orthogonal to the yaw direction and the pitch direction, for example.

  Reference numeral 4 denotes a first driver, which drives the first step motor 2 in accordance with a drive pulse output from the microcomputer 6. Reference numeral 5 denotes a second driver, which drives the second step motor 3 in accordance with a drive pulse output from the microcomputer 6. A microcomputer 6 outputs drive pulses to the first driver 4 and the second driver 5 in accordance with shake signals output from the first shake detection means 7 and the second shake detection means 8. Further, it is possible to control the first driver 4 and the second driver 5 so as to switch the applied voltage applied to the first step motor 2 and the second step motor 3. Further, the step motor control method can be changed according to the state of the release switch 9.

  Reference numeral 7 denotes first shake detection means, which outputs the shake of the camera 100 in the first direction to the microcomputer 6 as a shake signal. Reference numeral 8 denotes second shake detection means for outputting the shake of the camera 100 in the second direction to the microcomputer 6 as a shake signal. As the shake detection means 7 and 8, for example, a gyro sensor that detects an angular velocity of touch when the main body of the camera 100 is rotated by shaking can be used. Reference numeral 9 denotes a release switch or a release button. Reference numeral 10 denotes a memory for storing a drive control method described later. Reference numeral 11 denotes a mode switch for switching between the still image shooting mode and the moving image shooting mode. The microcomputer 6 is connected to the switches 9 and 11 and can know the respective states.

  Next, the shake correction operation will be described.

  FIG. 2 is a timing chart when shake correction is performed by the first control method.

CLK1 is a reference clock, T ₁ is the reference clock width when the microcomputer 6 outputs a driving pulse to the first driver 4. X ₁₀ is a driving target position in the first direction of the shake correcting lens 1. X ₁₁ is a drive target position of the first stepper motor 2, dx is the step width. P ₁ is a drive pulse output from the microcomputer 6 to the first driver 4. V ₁ is an applied voltage applied from the first driver 4 to the first stepping motor 2.

CLK2 is the reference clock, T ₂ is the reference clock width when the microcomputer 6 outputs a driving pulse to the second driver 5. X ₂₀ is a driving target position in the second direction of the shake correcting lens 1. X ₂₁ is a drive target position of the second stepper motor 3, dx represents a step width. P ₂ is a drive pulse output from the microcomputer 6 to the second driver 5. V ₂ is an applied voltage applied from the second driver 5 to the second stepping motor 3. W is the sum of the power consumption of the first step motor 2 and the power consumption of the second step motor 3.

The microcomputer 6 uses the shake signals input from the first shake detection means 7 and the second shake detection means 8 to drive target positions X ₁₀ and X of the lens 1 necessary for correcting the shake of the camera 100. ₂₀ is calculated. For example, the microcomputer 6 amplifies the shake signals from the shake detection means 7 and 8 after applying an appropriate filter, and converts the shake amount into a movement amount of the step motors 2 and 3. Then, the microcomputer 6 acquires the drive target positions X ₁₀ and X ₂₀ for each predetermined sampling period, and generates the drive pulses for the step motors 2 and 3 from the obtained movement amounts of the step motors 2 and 3. Specifically, when shake correction is started at t ₀ , the microcomputer 6 cumulatively drives the drive target position X ₁₀ and the first step motor 2 in the first direction of the shake correction lens 1 for each reference clock. Compare positions. Then, the microcomputer 6 updates the drive target position X ₁₁ of the first step motor 2 and outputs the drive pulse P ₁ to the first driver 4. The first driver 4 switches the voltage applied to the first step motor 2 in accordance with the drive pulse P ₁ and rotates the first step motor 2. As a result, the shake correction lens 1 is driven in the first direction to correct the shake. The second step motor 3 can also be shake-corrected by a similar operation.

  At this time, the power consumption W is expressed by the following equation, assuming that the applied voltage to each motor is equal VM and the resistance of each motor is equal RM.

  FIG. 3 is a timing chart when shake correction is performed by the second control method. The description of each symbol and the basic operation is based on the description of the first control method.

Unlike the first control method, the second control method provides a time difference dt between the reference clock CLK1 of the first step motor 2 and the reference clock CLK2 of the second step motor 3. The second control method includes an applied voltage V ₁ applied from the first driver 4 to the first step motor 2 and an applied voltage V ₂ applied from the second driver 5 to the second step motor. Are alternately applied by time division.

In the second control method, there is a limit to shorten the energization time TE of the applied voltage to each step motor from the relationship with the settling time of the step motor, and the reference clock widths T ₁ and T ₂ are the first. It needs to be larger than the control method. As a result, a tracking delay occurs between the drive targets X ₁₁ and X ₂₁ of the step motor relative to the drive targets X ₁₀ and X _{20 of} the shake correction lens 1 as compared with the first control method. Further, the power consumption W is expressed by the following equation, assuming that the applied voltage to each motor is equal VM and the resistance of each motor is equal RM.

  That is, in the second control method, the shake correction speed is reduced as compared with the first control method, but the power consumption can be suppressed to ½.

  FIG. 4 is a timing chart in the case where shake correction is performed in a different embodiment of the second control method. The description of each symbol and the basic operation is based on the description of the second control method.

In this embodiment, the applied voltage V ₁ applied from the first driver 4 to the first step motor 2 and the applied voltage V ₂ applied from the second driver 5 to the second step motor are time-shared. Were applied alternately. Further, when the drive pulses P ₁ and P ₂ are not output, the applied voltages V ₁ and V ₂ to each step motor are not applied. As a result, compared to the second control method described above, it is possible to further reduce power consumption without reducing the shake correction speed.

  Next, the change of the driving method by the release switch 9 will be described. The release switch 9 changes the operation mode of the camera 100 by half-pressing and full-pressing.

  The time required for shake correction at the time of still image shooting is roughly divided into an aiming time and an exposure time. The aiming time is the time for zooming or focusing while looking through the viewfinder or monitor, and the exposure time is the time during which the subject is actually imaged on the imaging surface when the release switch 9 is pressed. In normal shooting, the aiming time is longer than the exposure time, and power saving of the aiming time becomes a problem. In addition, in the exposure time, it is required to perform shake correction with high accuracy and obtain a good image.

  Therefore, in this embodiment, the microcomputer 6 is set so that the time of aiming and the time of exposure are determined according to the state of the release switch 9 and the control method can be switched. That is, the second control method with low power consumption during aiming and the first control method with high shake correction performance during exposure are performed. As a result, while reducing the power consumption of the aiming time, a good image with no shake can be obtained without deteriorating the shake correction performance of the exposure time.

  FIG. 5 is a flowchart for explaining the operation (control method) of the camera 100. Hereinafter, the operation of the camera 100 will be described with reference to FIG.

  When a power switch (not shown) of the camera 100 is turned on and the power of the camera is turned on (step S01), a shutter (not shown) is opened (step S02), and the release switch 9 and the power switch are monitored (step S15). . When the state of the release switch 9 is SW1 ON, the control method of the step motors 2 and 3 is set to the control method 2 (step S04), and the shake correction is turned ON (step S05). This state is a state of shake correction during aiming. Subsequently, the release switch 9 is monitored while performing autofocus (step S06) and exposure setting (step S07) (step S08).

  When the state of the release switch 9 becomes SW2 ON, the microcomputer 6 sets the control method of the step motors 2 and 3 to the control method 1 (step S09), and starts the shake correction operation at the time of exposure. Thus, the image sensor is reset (step S10), the shutter is closed (step S11), and the image is transferred (step S12), thereby completing the exposure operation. When the exposure operation is completed, the shake correction is turned off (step S13), the shutter is opened (step S14), and the release switch 9 and the power switch are again monitored (step S15). When the power switch of the camera 100 is turned off in this state, the power of the camera 100 is turned off (step S16).

  Next, with reference to FIG. 6, an embodiment using the mode switch 11 will be described. Here, FIG. 6 is a flowchart for explaining a control method using the mode switch 11. In the camera 100 capable of switching between the still image shooting mode and the moving image shooting mode, generally, the time required for shake correction for one shooting is longer during moving image shooting, and power saving during moving image shooting becomes a problem. Therefore, in this embodiment, the microcomputer 6 is set so that the control method can be switched by determining whether still image shooting or moving image shooting is performed according to the state of the mode switch 11. That is, the microcomputer 6 determines whether the switch 11 is in the still image shooting mode (step S20), and if so, performs the first control method with high shake correction performance (step S21). On the other hand, if the microcomputer 6 determines that the switch 11 is in the moving image shooting mode (step S22), the microcomputer 6 performs the second control method with low power consumption (step S23). As a result, while reducing the power consumption during moving image shooting, the shake correction performance during still image shooting is not deteriorated, and a good image without shake can be obtained. Of course, it is preferable to further divide the contents of step S21 as shown in FIG.

  According to the present embodiment, in the still image shooting, all the step motors are always energized to realize high quality shooting by high-speed camera shake correction. In this embodiment, in other operations such as aiming and moving image shooting, a plurality of step motors are alternately energized in a time-division manner to reduce camera shake correction, thereby realizing power saving and recording for a long time. The noise is reduced.

  The optical apparatus of the present embodiment may be a lens-integrated camera provided with a step motor, switching means, and control means, or an interchangeable lens attached to the camera. It may be a camera system in which the means and the control means are on the camera side.

It is a schematic block diagram of the digital camera which is one Example of this invention. It is a timing chart of the 1st control method of the camera shown in FIG. 6 is a timing chart of a second control method for the camera shown in FIG. 1. It is a timing chart of the modification of the 2nd control method shown in FIG. It is a flowchart explaining the control method which the camera shown in FIG. 1 performs using a release switch. It is a flowchart explaining the control method which the camera shown in FIG. 1 performs using a mode switch.

Explanation of symbols

1 Lens 6 Microcomputer 2, 3 Stepping motor 4, 5 Driver 9 Release switch 11 Mode switch 100 Camera

Claims (4)

An optical apparatus having a plurality of step motors for moving an optical element,
Switching means for switching the operation of the optical device;
Driving means for driving the step motors;
When the switching means is in the first state, the driving means applies a voltage to at least two of the step motors simultaneously, and the driving means is in a second state different from the first state. An optical apparatus comprising: a control unit that controls the driving unit so as to alternately apply a voltage to the plurality of stepping motors in a time-sharing manner.   The optical apparatus according to claim 1, wherein the switching unit is a release switch for starting a photographing operation, and the first state is a still image photographing state.   2. The switch according to claim 1, wherein the switching means is a switch for switching between moving image shooting and still image shooting, wherein the first state is a still image shooting state and the second state is a moving image shooting state. The optical apparatus described in 1. Determining whether the state of the switching means for switching the operation of the optical apparatus having a plurality of step motors for moving the optical element is the first state;
Determining whether the switching means is in a second state different from the first state;
Applying a voltage simultaneously to at least two of the plurality of step motors when the switching means determines that it is in the first state; and
And a step of alternately applying a voltage to the plurality of stepping motors in a time division manner when the switching unit determines that the second state is established.