JP2006243204A - Lens drive device, imaging apparatus, lens drive method and recording medium on which this method is recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive device capable of performing an operation by supplying the smallest amount of power that is required, without increasing time needed for lens groups to move. <P>SOLUTION: The lens drive device independently and simultaneously controls a current value for a first stepping motor 9 and a current value for a second stepping motor 13 in accordance with the direction of a zooming operation performed by the first drive lens group 3 and the second drive lens group 4. The operation is performed by supplying the smallest amount of power that is required, in accordance with the state of the zooming operation without increasing time needed for the lens groups to move. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens driving device, an imaging device, a lens driving method, and a recording medium on which the method is recorded for driving a first lens group and a second lens group, and in particular, a zoom function and a focus. It is suitable for application to a lens group that performs the matching function.

  For example, digital still cameras and the like are equipped with an autofocus function for automatically focusing and a zoom function for changing the magnification. Mobile phone cameras have also been equipped with autofocus and zoom functions. Such a camera is provided with a zoom lens for changing the magnification and a focus lens for focusing. Since it is necessary to reduce the size of a small camera or a mobile phone camera including a lens driving device, a structure in which a zoom lens and a focus lens are driven by separate motors (stepping motors) is employed.

  When using the zoom function, the zoom lens and the focus lens are moved simultaneously, and the focus lens is moved at a predetermined position to perform focusing at a predetermined magnification. The zoom lens and the focus lens are simultaneously driven by power (electric power) capable of obtaining a sufficient torque necessary for movement in order to perform a zoom operation in a short time. In order to save power consumption when moving the lens of the zoom function when the power supply voltage is lowered, it is known to drive two motors independently (see, for example, Patent Document 1 and Patent Document 2). ).

  When using a zoom function and a camera that has an autofocus function and simultaneously driving the zoom lens and focus lens with different stepping motors using the zoom function, the torque required to move the stepping motors of the two lens groups during zooming Therefore, there is a limit in saving power consumption.

As disclosed in Patent Document 1, when current consumption is suppressed, the simultaneous driving of the lens groups is stopped, and the driving motor for the front lens group and the driving motor for the rear lens group are independently driven. Power consumption. However, since the two lens groups are moved independently, there is a problem that the zoom operation takes time.
JP-A-6-324245 JP 2004-144945 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens driving device that can operate by turning on a power source to the minimum necessary without increasing the movement time of the lens group. . Moreover, it aims at providing the imaging device provided with this lens drive device.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a lens driving method capable of operating by operating a power source as much as possible without lengthening the movement time of the lens group. . It is another object of the present invention to provide a recording medium on which this lens driving method is recorded.

  In order to achieve the above object, a first aspect of the present invention includes a first lens group that moves in the optical axis direction by a first driving unit to perform a first operation, and includes: A second lens group having the same optical axis and moving in the optical axis direction by the second driving means to perform an operation of correcting at least a relative position with respect to the first lens group; A lens driving device comprising control means for independently and simultaneously controlling the driving force of the first driving means and the driving force of the second driving means in accordance with the movement state of the lens group and the second lens group It is in.

  In the first aspect of the present invention, the driving force of the first driving means and the driving force of the second driving means are independently and simultaneously controlled according to the movement state of the first lens group and the second lens group. Therefore, the operation can be performed by turning on the power source as much as possible without lengthening the movement time of the lens group according to the movement state.

  In order to achieve the above object, the second aspect of the present invention includes a first lens group that moves in the optical axis direction by a first drive motor to perform a zoom operation, and is identical to the first lens group. A first lens group having a second lens group having an optical axis and moving in the optical axis direction by a second drive motor to correct at least a focal plane at a predetermined zoom position by the first lens group; And a lens driving device comprising control means for independently controlling the power of the first drive motor and the power of the second drive motor in accordance with the movement state of the second lens group.

  In the second aspect of the present invention, the power of the first drive motor and the power of the second drive motor are independently and simultaneously controlled according to the movement status of the first lens group and the second lens group. The operation can be performed by turning on the power source as much as possible without lengthening the movement time of the lens group according to the movement situation.

  According to a third aspect of the present invention, in the second aspect, the control means sets the power of the first drive motor that drives the first lens group to a sufficient power necessary for the movement during the zoom operation. In addition, the lens driving apparatus is provided with a function of setting the power of the second drive motor that drives the second lens group to the minimum power required for movement.

  In the third aspect, the operation can be performed with the power source of the second drive motor as the minimum power necessary for movement and the power source being input to the minimum necessary.

  According to a fourth aspect of the present invention, in the second aspect, during the zoom operation, the control means sets the power of the driving motor of the lens group on the front side in the movement direction to a sufficient power necessary for movement, and after the movement direction. The lens driving device is provided with a function of setting the power of the drive motor on the side to the minimum power required for movement.

  In the fourth aspect of the present invention, the operation can be performed by turning on the power source to the minimum necessary with the electric power of the drive motor on the rear side in the movement direction as the minimum electric power necessary for the movement.

  According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the drive motor is a stepping motor, and the power necessary for moving the lens group is derived from the relationship between the drive required torque and the drive frequency. The lens driving device is characterized in that.

  In the fifth aspect, the operation can be performed by turning on the power source to the minimum necessary amount by the electric power derived from the relationship between the required driving torque and the driving frequency.

  In order to achieve the above object, a sixth aspect of the present invention resides in an imaging apparatus including the lens driving device according to any one of the first to fifth aspects.

  According to the sixth aspect of the present invention, the imaging apparatus includes a lens driving device that can operate with a power source as much as possible without lengthening the movement time of the lens group.

  In order to achieve the above object, the seventh aspect of the present invention provides a moving direction during zooming of the first lens group that performs a zoom operation and the second lens group that corrects the focal plane at least at a predetermined zoom position. The required driving force corresponding to the above is obtained, and at the time of zooming, the first lens group is moved with a sufficient driving force necessary for movement, and the second lens group is moved with a minimum driving force necessary for movement. The lens driving method is characterized.

  In the seventh aspect of the present invention, during zooming, the second lens group is moved with the minimum driving force necessary for movement, and the power source is turned on to the minimum necessary without increasing the movement time of the lens group. Can be operated.

  The eighth aspect of the present invention for achieving the above object is the movement direction during zooming of the first lens group that performs the zoom operation and the second lens group that corrects the focal plane at least at a predetermined zoom position. When zooming, the front lens group in the moving direction is moved with sufficient driving force necessary for movement, and the rear lens group in the moving direction is moved with the minimum driving force necessary for moving. The lens driving method is characterized by moving the lens.

  In the eighth aspect of the present invention, at the time of zooming, the lens group on the rear side in the movement direction is moved with the minimum driving force necessary for movement, and the power source is minimized without increasing the movement time of the lens group. Can be operated.

  In order to achieve the above object, a ninth aspect of the present invention is a recording of a program or data for causing a lens driving method of the seventh or eighth aspect to be executed by a computer, which is processed by the computer. The present invention resides in a recording medium on which a lens driving method is recorded.

  According to the ninth aspect of the present invention, it is possible to provide a recording medium on which a lens driving method capable of performing an operation by turning on a power source as much as possible without lengthening the moving time of the lens group.

  The lens driving device of the present invention can be operated with the power source being turned on to the minimum necessary without lengthening the movement time of the lens group.

  The imaging device according to the present invention can be an imaging device provided with a lens driving device that can operate with a power source as much as possible without lengthening the movement time of the lens group.

  The lens driving method of the present invention can be operated with the power source being turned on to the minimum necessary without lengthening the movement time of the lens group.

  The recording medium of the present invention can be a recording medium on which is recorded a lens driving method capable of operating with a power source as much as possible without lengthening the movement time of the lens group.

  FIG. 1 is a schematic block diagram of a lens driving device according to an embodiment of the present invention, FIG. 2 is a relationship between torque and frequency, FIG. 3 is a flow of zoom operation, and FIGS. FIG. 8 to FIG. 11 show the state of the lens group during the zoom operation toward the low magnification side.

  The lens driving device of the present invention is used in an imaging device such as a digital still camera or a mobile phone camera.

  A schematic configuration of the lens driving device will be described with reference to FIG.

  As shown in the figure, between the first fixed lens group 1 on the subject side and the second fixed lens group 2 on the image sensor side, a focusing operation is performed with the first drive lens group 3 that performs a zoom operation. A second drive lens group 4 is provided. The first drive lens group 3 is supported by the first lens frame 5, and the second drive lens group 4 is supported by the second lens frame 6.

  The first lens frame 5 is screwed into the first feed screw 7, and can be reciprocated in the direction along the optical axis X by the rotation of the first feed screw 7. The first feed screw 7 is driven by a first stepping motor 9 which is a first drive motor via a first speed reduction means 8. The second lens frame 6 is screwed into the second feed screw 11, and can be reciprocated in the direction along the optical axis X by the rotation of the second feed screw 11. The second feed screw 11 is driven by a second stepping motor 13, which is a second drive motor, via a second speed reduction means 12.

  The first stepping motor 9 and the second stepping motor 13 are driven at a predetermined frequency according to commands from the drivers 15 and 16, respectively, and the drivers 15 and 16 are operated according to commands from the CPU 17. The CPU 17 is connected to a ROM 18 and a RAM 19. On the other hand, driving current switching circuits 21 and 22 are connected to the drivers 15 and 16, respectively. The drivers 15 and 16 stop driving and drive the current at a low current with respect to the first stepping motor 9 and the second stepping motor 13. Different commands from high current drive at high current are output independently.

  For this reason, the zoom operation can be performed with the minimum power required and the minimum power required. As an example, the total stroke of the lens group is 7 mm, the moving distance of one pulse of the stepping motor is 10 μm, the feeding speed is 500 PPS, and the moving time of the full stroke is about 1.4 seconds.

  In the lens driving device configured as described above, during the zoom operation, the first stepping motor 9 and the second stepping motor 13 are simultaneously driven to move the first driving lens group 3 and the second driving lens group 4 to a predetermined magnification position. Then, only the second stepping motor 13 is driven at a predetermined magnification position to move the second driving lens group 4 to perform focusing. When moving to the specified magnification, the stepping motor on the front side in the moving direction is driven with a current (a value obtained by adding a large margin) necessary for moving, and the stepping motor on the rear side in the moving direction is moved. Drive with current (minimum margin value) which is the minimum power required. The second stepping motor 13 is driven with a current having a value obtained by adding a large margin value during focusing.

  During the zoom operation, the first stepping motor 9 for zoom operation is driven with a current having a large margin value, and the second stepping motor 13 for focusing is driven with a current having a small margin value, regardless of the moving direction. It is also possible. In this case, when the second drive lens group 4 is on the front side in the movement direction (low-magnification side zoom), means for preventing the lens frame from being buffered is taken.

  Further, the first drive lens group 3 and the second drive lens group 4 are supported by one lens frame, and the second drive lens group 4 is relative to the first drive lens group 3 in the lens frame. The first driving lens group 3 and the second driving lens group 4 are zoomed simultaneously by moving one lens frame by the first stepping motor 9, and the second stepping motor 13 at a predetermined position. The second driving lens group 4 may be moved relatively to perform a focusing operation. In this case, for example, the first stepping motor 9 is always driven with a current having a large margin value, and the second stepping motor 13 is always driven with a current having a small margin value.

As shown in FIG. 2, the current value (mA) of the relationship between the frequency (PPS) of the stepping motor and the torque (× 10 ⁻⁴ N · m) is previously mapped and stored. For example, when the torque required for driving is 0.3 (× 10 ⁻⁴ N · m), the frequency is 100 (mA) and the frequency is 1200 (PPS), and the current value obtained by adding a small margin to the required current value is 110 (mA), and a current value obtained by adding a large margin value to the required current value is 140 (mA).

  The operation of the lens driving device described above will be specifically described with reference to FIGS. 4 to 7 show the state of the lens group during zooming to the high magnification side, FIG. 4 shows the state at the start of movement, FIG. 5 shows the state during the movement, FIG. 6 shows the state at the end of movement, and FIG. Indicates the state during focusing. 8 to 11 show the state of the lens group during zooming to the low magnification side, FIG. 8 shows the state at the start of movement, FIG. 9 shows the state during the movement, FIG. 10 shows the state at the end of movement, FIG. 11 shows a state during focusing.

  As shown in FIG. 3, it is determined whether or not zooming is started in step S1, and if it is determined that zooming is started, the current value necessary for obtaining the driving torque of the first driving lens group 3 in step S2. Is set to I1, and a current value necessary for obtaining the driving torque of the second driving lens group 4 is set to I2.

  If the zoom direction is determined in step S3 and it is determined that the zoom is on the high magnification side, then in step S4, the current value I1 required to obtain the drive torque of the first drive lens group 3 is large. Is a current value I1, and a value obtained by adding a small margin to the current value I2 required to obtain the driving torque of the second drive lens group 4 is referred to as a current value I2.

  For example, in the case shown in FIG. 2 described above, when the current value for obtaining the torque necessary for driving is 100 (mA), the current value I1 is set to 140 (mA) and the current value I2 is set to 110 (mA). .

  After setting the current values I1 and I2 in step S4, in step S5, the first stepping motor 9 is driven with the current value I1 (high current drive), and the second stepping motor 13 is driven with the current value I2 (low). Current drive), the first drive lens group 3 and the second drive lens group 4 are moved to a state in which the zoom operation to the high magnification side is performed (see FIGS. 4 and 5). In step S6, it is determined whether or not zooming has ended. If zooming has not ended, the processing in step S5 is repeated. If it is determined in step S6 that the zoom has been completed, the first stepping motor 9 and the second stepping motor 13 are stopped (see FIG. 6).

  Next, a value obtained by adding a large margin value to the current value I2 necessary for obtaining the driving torque of the second driving lens group 4 in step S7 is defined as a current value I2. In step S8, the second stepping motor 13 is driven at a current value I2 (high current drive), the second drive lens group 4 is moved, and a focus correction operation (focusing operation) is performed (see FIG. 7). The process ends.

  The above is the flow of processing during the zoom operation to the high magnification side.

  On the other hand, if it is determined in step S3 that the zoom direction is on the low magnification side, in step S9, a small margin value is added to the current value I1 required to obtain the driving torque of the first driving lens group 3. The value is the current value I1, and the current value I2 is a value obtained by adding a large margin value to the current value I2 required to obtain the drive torque of the second drive lens group 4.

  After setting the current values I1 and I2 in step S9, in step S10, the first stepping motor 9 is driven with the current value I1 (low current driving), and the second stepping motor 13 is driven with the current value I2 (high). Current drive), the first drive lens group 3 and the second drive lens group 4 are moved to a state in which the zoom operation to the low magnification side is performed (see FIGS. 8 and 9). In step S11, it is determined whether or not zooming has ended. If zooming has not ended, the processing in step S10 is repeated. If it is determined in step S11 that the zoom has been completed, the first stepping motor 9 and the second stepping motor 13 are stopped (see FIG. 10).

  If it is determined in step S11 that zooming has been completed, a value obtained by adding a large margin value to the current value I2 necessary for obtaining the drive torque of the second drive lens group 4 in step S12 is defined as a current value I2. In step S13, the second stepping motor 13 is driven at a current value I2 (high current drive), the second drive lens group 4 is moved, and a focus correction operation (focusing operation) is performed (see FIG. 11). The process ends.

  Although the example in which the second stepping motor 13 is driven by the high current drive in the focus correction operation is shown, the focus correction operation can also be performed by the low current drive. It is also possible to perform the focus correction operation by moving both the first drive lens group 3 and the second drive lens group 4.

  A program to be executed by a computer is assembled to control the above-described processing, and program data and the like are recorded on a recording medium so that the processing by the computer is possible.

  Accordingly, since the current value of the first stepping motor 9 and the current value of the second stepping motor 13 are independently and simultaneously controlled according to the direction of the zoom operation of the first drive lens group 3 and the second drive lens group 4. Depending on the state of the zoom operation, the operation can be performed with the minimum power applied without increasing the movement time of the lens group. For this reason, it becomes possible to reduce power consumption, without extending operating time. Since the current of the stepping motor of the lens group on the front side in the movement direction is set to a sufficient current necessary for movement, and the current of the stepping motor on the rear side in the movement direction is set to the minimum current required for movement, the lens frames No buffering or the like occurs.

  Incidentally, as the first operation and the operation for correcting the relative position with respect to the first drive lens group 3 in the first operation, the zoom lens origin return operation and the positioning of the focus adjustment lens with respect to the zoom lens after the origin return. It is also possible to apply to the operation.

  INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field of a recording medium on which a lens driving device, an imaging device, a lens driving method, and a method for driving the first lens group and the second lens group are recorded. it can.

1 is a schematic block configuration diagram of a lens driving device according to an embodiment of the present invention. It is a graph showing the relationship between a torque and a frequency. It is a flowchart of a zoom operation. It is a state explanatory view of the lens group at the time of zoom operation to the high magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the high magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the high magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the high magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the low magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the low magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the low magnification side. It is a state explanatory view of the lens group at the time of zoom operation to the low magnification side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st fixed lens group 2 2nd fixed lens group 3 1st drive lens group 4 2nd drive lens group 5 1st lens frame 6 2nd lens frame 7 1st feed screw 8 1st deceleration means 9 1st 1 stepping motor 11 second feed screw 12 second reduction means 13 second stepping motor 15, 16 driver 17 CPU
18 ROM
19 RAM

Claims (9)

  The first lens unit includes a first lens group that moves in the optical axis direction by the first driving unit and performs a first operation, and has the same optical axis as the first lens unit, and the optical axis direction by the second driving unit. And a second lens group that performs an operation of correcting at least a relative position with the first lens group, and the first lens group and the second lens group are moved in accordance with the movement status of the first lens group and the second lens group. A lens driving device comprising control means for simultaneously and independently controlling the driving force of the driving means and the driving force of the second driving means.   A first lens group that moves in the optical axis direction by the first drive motor to perform a zoom operation and has the same optical axis as the first lens group and moves in the optical axis direction by the second drive motor And a second lens group for correcting the focal plane at a predetermined zoom position by at least the first lens group, and the first driving according to the movement state of the first lens group and the second lens group. A lens driving device comprising control means for simultaneously and independently controlling the power of the motor and the power of the second drive motor.   According to a second aspect of the present invention, the control means sets the power of the first drive motor that drives the first lens group to a sufficient power necessary for movement and drives the second lens group during the zoom operation. A lens driving device having a function of setting the power of a second driving motor to be a minimum power required for movement.   3. The control unit according to claim 2, wherein the power of the driving motor for the lens group on the front side in the movement direction is set to a sufficient power necessary for movement and the power of the driving motor on the rear side in the movement direction is required for movement during the zoom operation A lens driving device characterized by having a function of generating a minimum electric power.   5. The lens driving device according to claim 2, wherein the driving motor is a stepping motor, and the electric power necessary for moving the lens group is derived from the relationship between the driving required torque and the driving frequency.   An imaging apparatus comprising the lens driving device according to claim 1.   The required driving force corresponding to the moving direction during zooming of the first lens group that performs the zoom operation and the second lens group that corrects the focal plane at least at a predetermined zoom position is obtained. A lens driving method comprising: moving a group with a sufficient driving force necessary for movement, and moving the second lens group with a minimum driving force necessary for movement.   The required driving force corresponding to the moving direction during zooming of the first lens group that performs the zoom operation and the second lens group that corrects the focal plane at least at a predetermined zoom position is obtained. The lens group is moved with a sufficient driving force necessary for the movement, and the lens group on the rear side in the movement direction is moved with the minimum driving force necessary for the movement.   9. A recording medium on which a lens driving method according to claim 7 or 8 is recorded. The recording medium stores a program or data for causing a computer to execute the lens driving method and can be processed by a computer. .

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