JP5326681B2 - LENS DRIVE DEVICE AND IMAGING DEVICE - Google Patents

Description

  The present invention relates to a lens driving device including a shape memory alloy actuator that moves when the lens is deformed by supplying heat, and an imaging device including the lens driving device.

  Conventionally, as a lens driving device having a shape memory alloy actuator, by supplying electric power to the actuator, the actuator generates heat and contracts to move the lens in a predetermined direction, and the actuator naturally dissipates and extends the lens. A lens driving device configured to move the lens in the opposite direction is known.

  And an imaging device provided with such a lens driving device controls the position of the lens by a resistance value corresponding to the deformation amount of the actuator, that is, a resistance value that descends by contraction and rises by extension (for example, Patent Document 1).

Specifically, when the imaging device places the lens at a predetermined position, the voltage is applied to cause the actuator to generate heat or to stop applying the voltage so as to obtain a resistance value corresponding to the predetermined position of the lens. To let the actuator naturally dissipate heat. Then, the imaging device recognizes that the lens is positioned at a predetermined position when the resistance value of the actuator becomes a predetermined value (predetermined resistance value) corresponding to the predetermined position of the lens.
JP 2007-217114 A

  Here, in such an imaging apparatus, in order to set the resistance value of the actuator to a predetermined value, when the resistance value is larger than the predetermined value, a voltage is applied to the actuator, and when the resistance value is smaller than the predetermined value, Stop applying voltage to the actuator. Then, by repeatedly applying a voltage to the actuator or stopping the actuator, the resistance value of the actuator gradually converges to a predetermined value.

  Thus, even if the resistance value of the actuator can be maintained substantially constant, it is practically difficult to maintain it completely constant. In other words, it is difficult to completely fix the lens position microscopically (strictly or microscopically) in the imaging apparatus. Therefore, when it is recognized that the lens is positioned at a predetermined position when the resistance value of the actuator is not yet stable, that is, when the position of the lens is not microscopically stable, it is obtained via the lens. Data is unstable or unreliable.

  Therefore, in view of such circumstances, it is an object of the present invention to provide a lens driving device and an imaging device that can obtain stable and reliable data through a lens.

The lens driving device according to the present invention includes a lens, an actuator of a shape memory alloy that is deformed by supplying heat and moves the lens, and a resistance value of the actuator that is changed by deformation of the actuator. A detecting means for outputting a detection signal when detecting that the resistance value of the actuator is maintained in a predetermined range for a predetermined time. Features.

  According to the lens driving device of the present invention, it can be detected that the resistance value of the actuator is maintained within a predetermined range. Accordingly, it can be recognized that the lens is positioned at a predetermined position in a state where the resistance value of the actuator is stable, that is, in a state where the position of the lens is microscopically stable.

  An imaging device according to the present invention is an imaging device including the lens driving device described above and an imaging element that receives light through the lens, and the lens is configured to be movable in a region corresponding to a focus region. The control means moves the lens stepwise from a position corresponding to the first field in order to acquire imaging data for each field provided in the focus area, and also uses the acquired imaging data to The target position where the lens is finally positioned is calculated, and the lens is positioned at the target position.

  According to the imaging apparatus of the present invention, the lens that can move in the area corresponding to the focus area is moved stepwise from the position corresponding to the first field among the fields provided in the focus area. Thereby, imaging data can be acquired for each field, a target position where the lens is finally positioned can be calculated from the acquired imaging data, and the lens can be positioned at the target position.

  Therefore, for example, whether each imaging data is acquired in a state where the lens position is microscopically stable, or whether each imaging data is acquired in a state where the lens position is microscopically stable. Judgment can be made.

  In the imaging device according to the present invention, the detection unit detects that the resistance value of the actuator is maintained within a predetermined range during the time when the control unit has acquired the imaging data of the predetermined field. When the detection signal is output, the control means moves the lens to a position corresponding to the next field, and when the detection signal is not output. The imaging data of the predetermined field may be acquired again.

  According to the imaging apparatus having such a configuration, a detection signal is output when it is detected that the resistance value of the actuator is maintained within a predetermined range during the time when the control unit acquires the imaging data of the predetermined field. . When a detection signal is output, it is determined that each image data has been acquired in a state where the lens position is microscopically stable, and the lens is moved to a position corresponding to the next field, while the detection is performed. If no signal is output, it is determined that each image data has been acquired in a state where the position of the lens is not microscopically stable, and image data of a predetermined field is acquired again.

  In the imaging device according to the present invention, the detection means maintains the resistance value of the actuator within a predetermined range so as to notify that the lens is located at a position corresponding to the first field. When this is detected, a detection signal may be output, and the control means may acquire imaging data in the first field after the detection signal is output.

  According to the imaging apparatus having such a configuration, when it is detected that the resistance value of the actuator is maintained within a predetermined range, the detection unit outputs a detection signal, so that the lens is positioned at a position corresponding to the first field. Notify that you are located. Then, after the detection signal is output, the control means acquires the imaging data of the first field, so that the first position is microscopically stable at the position corresponding to the first field. Field imaging data can be acquired.

  Further, in the imaging apparatus according to the present invention, the detection means maintains the resistance value of the actuator within each predetermined range so as to notify that the lens is located at a position corresponding to each field. When detecting this, each detection signal may be output, and the control means may acquire imaging data in each field after the detection signal is output.

  According to the imaging apparatus having such a configuration, when detecting that the resistance value of the actuator is maintained within a predetermined range, the detection unit outputs a detection signal, so that the lens is positioned at a position corresponding to each field. Notify that Then, after the detection signal is output, the control means acquires the imaging data of each field, so the imaging data of each field is acquired in a state where the position of the lens is microscopically stable at the position corresponding to each field. can do.

  In the imaging device according to the present invention, the detection unit detects that the resistance value of the actuator is maintained within a predetermined range in order to notify that the lens is located at the target position. When the detection signal is output, the control means may acquire the imaging data after the detection signal is output.

  According to the imaging apparatus having such a configuration, the detection means outputs a detection signal when detecting that the resistance value of the actuator is maintained within a predetermined range, so that the lens is positioned at the target position. Notice. Then, after the detection signal is output, the control means acquires the imaging data of the target position, so that the imaging data of the target position can be acquired in a state where the lens position is microscopically stable at the target position.

  As described above, according to the lens driving device and the imaging device according to the present invention, it can be recognized that the lens is positioned at a predetermined position while the position of the lens is microscopically stable. Thus, it is possible to obtain an excellent effect that data having stability and reliability can be obtained.

  Hereinafter, an embodiment of a lens driving device and an imaging device according to the present invention will be described with reference to FIGS. Note that the case where the lens driving device according to the present embodiment is employed in an imaging device will be described.

  As shown in FIG. 1, the imaging apparatus according to the present embodiment includes a lens driving device 1, and the lens driving device 1 includes lenses 2, 2 and lenses 2, 2 to be accommodated in the optical axis direction (A in FIG. 1). A lens barrel 3 that can move in the direction of a double-headed arrow, and a shape memory alloy (SMA) that deforms by supplying heat (for example, voltage (power, current)) and moves the lenses 2 and 2 through the lens barrel 3. ) Actuator 4. In addition, you may provide an external heater etc. separately as a means to supply calorie | heat amount.

  The imaging device includes an imaging element 5 that receives light through the lenses 2 and 2, a casing 6 that houses the lens barrel 3, and a substrate 7 on which the imaging element 5 is mounted and fixed to the casing 6. Prepare. The imaging device also includes a display device 8 that outputs and displays imaging data received by the imaging element 5 on a screen.

  The lens driving device 1 detects that the resistance value of the actuator 4 is maintained within a predetermined range, and the control means 9 that controls the positions of the lenses 2 and 2 based on the resistance value of the actuator 4 that changes due to the deformation of the actuator 4. And detecting means 10 for performing.

  The lenses 2 and 2 are integrated with the lens barrel 3 and configured to be movable in a region corresponding to a focus region in the imaging apparatus (hereinafter also referred to as “moving region”). In the present embodiment, two lenses 2 and 2 are provided. However, the present invention is not limited to such a case, and one or three or more lenses may be provided.

  The lens barrel 3 is formed in a cylindrical shape, and is arranged so that the axis coincides with the optical axis. Further, the lens barrel 3 includes a guided portion (not shown or numbered) guided by a guide portion (not shown or numbered) provided in the housing 6 in order to move stably in the optical axis direction. .

  The actuator 4 is configured in a V shape (in FIG. 1, two sides of the V shape are overlapped). The actuator 4 is fixed to the lens barrel 3 and the housing 6 respectively. When a voltage is applied, the actuator 4 is deformed (expanded / contracted) in the direction of the optical axis (direction of arrow B in FIG. 1) as a whole. As a result, the distance between the lens barrel 2 and the housing 5 is adjusted to move the lenses 2 and 2.

  Specifically, the actuator 4 generates heat and contracts when a voltage is applied, thereby moving the lenses 2 and 2 in a predetermined direction, and naturally radiates and extends the lenses 2 and 2 with the predetermined direction. Configured to move in the opposite direction. More specifically, the actuator 4 separates the lenses 2 and 2 and the image sensor 5 by contracting, while bringing the lenses 2 and 2 and the image sensor 5 close to each other by extending.

  The control means 9 controls the position of the lenses 2 and 2 by controlling the deformation amount of the actuator 4 while monitoring the resistance value of the actuator 4 corresponding to the deformation amount of the actuator 4. Then, in order to acquire the imaging data for each field provided in the focus area, the lenses 2 and 2 are moved stepwise from the position corresponding to the first field, and the lenses 2 and 2 are moved from the acquired imaging data. The target position to be finally positioned is calculated, and the lenses 2 and 2 are positioned at the target position.

  At this time, the control means 9 performs control so that the direction in which the lenses 2 and 2 are moved stepwise from the position corresponding to the first field is the direction in which the lenses 2 and 2 are moved as the actuator 4 contracts. . The control means 9 controls the amount of power supplied by modulating the voltage applied to the actuator 4 by pulse control (PWM control), that is, the time (pulse width) for applying a predetermined voltage value. ing.

  The detection means 10 outputs a detection signal when it is detected that the resistance value of the actuator 4 is maintained within a predetermined range for a predetermined time.

  The configuration of the imaging apparatus according to the present embodiment is as described above. Next, a method for controlling the imaging apparatus according to the present embodiment will be described. Specifically, a lens control method in the autofocus function of the imaging apparatus will be described with reference to FIGS.

First, as shown in FIG. 2, the control means 9 gradually moves the lenses 2 and 2 that can move in the moving region (C region in FIG. 2) from the position P ₀₁ corresponding to the first field ( Hereinafter, before the “first scan”), the lenses 2 and 2 are controlled to be positioned at a predetermined position (hereinafter also referred to as “standby position”, which is set to P ₀₅ in the present embodiment). .

  Here, before the first scan, the imaging apparatus is in an initial mode (for example, a state in which the power is turned on for a camera or a state in a camera mode for a mobile phone) or a standby mode (a camera or a mobile phone). In the state of waiting for the shutter to be operated).

When the image pickup apparatus is in an image pickup mode (a state in which the shutter is operated in the camera or the mobile phone), the control unit 9 stops applying the voltage to the actuator 4 and the actuator 4 is naturally dissipated to extend. moves the lens 2,2 from the standby position _{P 05} to position _{P 01} corresponding to the first field. The display device 8, lens 2, 2 are fixed to output display image data acquired up at the standby position P ₀₅ moves to a position P ₀₁ corresponding to the first field from the standby position P ₀₅ .

Here, the positioning of the lens will be described in detail with reference to FIGS. In FIGS. 3 and 4, the lens position corresponding to the nth field is denoted as _Pn, and the resistance value of the actuator corresponding to the nth field is _denoted as Rn.

First, as shown in FIG. 3, when the lens moves in the direction from the position P ₁₀ toward the position P ₀₁ , the actuator 4 extends (the lenses 2 and 2 approach the image sensor 5), whereby the actuator 4 When the lens moves in the direction from the position P ₀₁ to the position P ₁₀ , the actuator 4 is contracted (the lenses 2 and 2 are separated from the image sensor 5), so that the actuator 4 The resistance value decreases.

  As shown in FIG. 4, the control means 9 determines that the resistance value of the actuator 4 is within a predetermined range (hereinafter also referred to as “maintenance range”, D range in FIG. 4). When deviating from a range narrower than the predetermined range (hereinafter also referred to as “control range”, E range in FIG. 4), the voltage application signal is output or the voltage application signal being output is stopped.

  Specifically, when the resistance value of the actuator 4 deviates from the control range E, the control means 9 outputs a voltage application signal, while the resistance value of the actuator 4 deviates from the control range E to a smaller one. In this case, the control means 9 stops outputting the voltage application signal, so that the resistance value of the actuator 4 is maintained within the maintenance range D.

For example, in FIG. 4, in T _a, the resistance value of the actuator 4 is larger than the control range E, a voltage is applied to the actuator 4. Thereafter, the T _b, the resistance value of the actuator 4 is smaller than the control range E, the application of the voltage to the actuator 4 is stopped, Thereafter, the T _c, the resistance value of the actuator 4 is greater than the control range E Therefore, it is repeatedly controlled whether to apply a voltage, such as applying a voltage to the actuator 4 again.

  Here, the image pickup data received by the image pickup device 5 is periodically acquired by the control means 9 for a fixed time (F time in FIG. 4). In addition, the detection means 10 outputs a position maintenance signal when the resistance value of the actuator 4 is within the maintenance range D.

For example, in FIG. 4, since the resistance value of the actuator 4 is within the maintenance range D at _Td , a position maintenance signal is output. Thereafter, the T _e, the resistance value of the actuator 4 is smaller than the sustain range D, the position maintaining signal is not output, Thereafter, the T _f, the resistance value of the actuator 4 is the maintenance range D, the position The maintenance signal is output again.

  When the control means 9 continuously outputs the position maintenance signal at the time F when the imaging data of the predetermined field is acquired, that is, the resistance value of the actuator 4 is maintained within the predetermined range. In the case of detection, the detection means 10 outputs a detection signal. Thereby, when the detection signal is output, the control means 9 moves the lenses 2 and 2 to a position corresponding to the next field. On the other hand, when the detection signal is not output, the control means 9 again performs the predetermined field. Image data is acquired.

More specifically, since the position maintaining signal is not continuously output during the time F during which the control unit 9 acquires the imaging data during the times T _{1 to} T ₂ , the control unit 9 performs the first operation. Even when the acquisition of the imaging data of the field is completed, the detection means 10 does not output a detection signal. Thereby, the control means 9 acquires the imaging data of the first field again.

In time T _{2 to} T ₃ , since the position maintaining signal is continuously output at time F when the control unit 9 acquires the imaging data, when the control unit 9 completes the acquisition of the imaging data. The detection means 10 outputs a detection signal. Thereby, the control means 9 applies a voltage to the actuator 4 to move the lenses 2 and 2 in order to acquire the imaging data of the next second field.

Returning to FIG. 2, the control means 9 moves the lenses 2 and 2 stepwise to positions P ₀₂ , P ₀₃ ,... Corresponding to each field (in this embodiment, 10 fields are provided). The imaging data is acquired for each field provided in the focus area. At this time, the control means 9 calculates only the imaging data in a predetermined range from the two-dimensional data of the imaging data acquired for each field, and records the value obtained by this calculation as the focus evaluation value.

  And the control means 9 calculates the area | region (henceforth a "target area | region") containing the target position among each field from the acquired image data of each field. At this time, the control means 9 determines the area corresponding to the field where the focus evaluation value is maximized as the target area.

  For example, in FIG. 2, the focus evaluation value from the second field to the sixth field is higher than the focus evaluation value of the previous field, and the focus evaluation value of the seventh field is the focus evaluation value of the sixth field. Therefore, when the focus evaluation value of the seventh field is recorded, the area between the sixth and seventh fields is determined as the target area. That is, the first scan is finished without acquiring image data of all fields.

Next, as shown in FIG. 5, the control means 7 subdivides the target region (G region in FIG. 5) into a plurality of small fields (in this embodiment, nine adjacent pairs of fields). In order to acquire imaging data every time, the lenses 2 and 2 are moved stepwise from the position P ₀₆₀ (= P ₀₆ ) corresponding to the first small field (hereinafter also referred to as “second scan”). Say).

  At this time, the control means 9 performs control so that the direction in which the lenses 2 and 2 are moved stepwise from the position corresponding to the first small field is the direction in which the lenses 2 and 2 are moved as the actuator 4 contracts. To do.

Note that the control unit 9 has already acquired the imaging data for the first small field, and thus omits acquiring the imaging data, but considering the hysteresis, the lenses 2 and 2 are connected to the first small field. After returning to the position P ₀₆₀ corresponding to the small field, the position is moved to the position P ₀₆₁ corresponding to the second small field. And the control means 9 calculates the position corresponding to the small field with the maximum focus evaluation value as the target position from the acquired imaging data of each small field.

For example, in FIG. 5, the focus evaluation value from the second small field (lens position P ₀₆₁ ) to the sixth field (lens position P ₀₆₅ ) is higher than the focus evaluation value of the previous small field, Since it is determined that the focus evaluation value of the small field (lens position P ₀₆₆ ) is lower than the focus evaluation value of the sixth small field, the focus evaluation value of the seventh small field is recorded in the sixth small field. The corresponding position P ₀₆₅ is determined as the target position. That is, the second scan is terminated without acquiring all the small field image data.

  Thereafter, the control means 7 positions the lenses 2 and 2 at the target position. At this time, in consideration of hysteresis, the control means 7 moves the lenses 2 and 2 stepwise in the second scan (the lenses 2 and 2 are moved stepwise from the position corresponding to the first small field). The lens 2 is moved to the target position while moving the lens 2 in the same direction as the moving direction.

  When it is detected that the resistance value of the actuator 4 is maintained within the predetermined range, the detection means 10 outputs a detection signal to notify that the lenses 2 and 2 are located at the target position. The means 7 acquires imaging data after the detection signal is output.

  As described above, since the lens driving device 1 and the imaging device according to the present embodiment can detect that the resistance value of the actuator 4 is maintained within the predetermined range, the state in which the resistance value 4 of the actuator is stable, that is, It can be recognized that the lenses 2 and 2 are positioned at predetermined positions while the positions of the lenses 2 and 2 are microscopically stable. Therefore, there is an excellent effect that stable and reliable data can be obtained through the lenses 2 and 2.

  It should be noted that the lens driving device and the imaging device according to the present invention are not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

  For example, in the image pickup apparatus according to the present invention, the detection means 10 detects the resistance value of the actuator 4 to notify that the lenses 2 and 2 are located at positions corresponding to the respective fields (particularly the first field). May be output when each of them is maintained within each predetermined range, and the control means 9 may acquire the imaging data in each field after each detection signal is output. Such a configuration may be employed instead of the configuration according to the above-described embodiment, that is, the configuration in which data in the same field is acquired again when a detection signal is not output, or may be employed in combination. The detection signal may be determined by communication ACK (acknowledgment).

  In the imaging apparatus according to the above-described embodiment, the control unit 9 determines that the direction of the second scan (the direction in which the lenses 2 and 2 are moved stepwise from the position corresponding to the first small field) Although the case where control is performed so that the lenses 2 and 2 are moved in the contraction direction has been described, the present invention is not limited to this case, and the direction in which the lenses 2 and 2 are moved when the actuator 4 extends as shown in FIG. It is also possible to control so that

  INDUSTRIAL APPLICABILITY The lens driving device and the imaging device according to the present invention have an effect that stable and reliable data can be obtained via a lens, and can be used in electronic devices (imaging devices) such as digital cameras and digital videos. Useful.

1 is an overall schematic diagram illustrating an imaging apparatus according to an embodiment of the present invention. Correlation diagram between time and lens position of the imaging apparatus according to the embodiment In the imaging apparatus according to the embodiment, (a) is a correlation diagram between time and lens position, and (b) is a correlation diagram between time and actuator resistance. In the imaging apparatus according to the embodiment, (a) is a correlation diagram between time and the resistance value of the actuator, and (b) is a correlation diagram between time and various signals. Correlation diagram between time and lens position of the imaging apparatus according to the embodiment Correlation diagram between time and lens position of imaging apparatus according to another embodiment of the present invention

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Lens 3 Lens barrel 4 Actuator 5 Image sensor 6 Case 7 Board | substrate 8 Display apparatus 9 Control means 10 Detection means

Claims (6)

A lens, a shape memory alloy actuator that is deformed by the supply of heat and moves the lens, and a control unit that controls the position of the lens based on a resistance value of the actuator that changes due to the deformation of the actuator. A lens driving apparatus comprising: a detecting means for outputting a detection signal when detecting that the resistance value of the actuator is maintained in a predetermined range for a predetermined time . An imaging device comprising: the lens driving device according to claim 1; and an imaging device that receives light through the lens, wherein the lens is configured to be movable in a region corresponding to a focus region, and the control unit includes: In order to acquire imaging data for each field provided in the focus area, the lens is moved stepwise from a position corresponding to the first field, and the lens is finally positioned from the acquired imaging data. An image pickup apparatus that calculates a target position and positions the lens at the target position. The detection means outputs a detection signal when detecting that the resistance value of the actuator is maintained within a predetermined range during the time when the control means has acquired imaging data of a predetermined field, When the detection signal is output, the control unit moves the lens to a position corresponding to the next field. When the detection signal is not output, the control unit again captures the imaging data of the predetermined field. The imaging device according to claim 2 to acquire. The detection means outputs a detection signal when it is detected that the resistance value of the actuator is maintained within a predetermined range in order to notify that the lens is located at a position corresponding to the first field. The imaging apparatus according to claim 2, wherein the control unit acquires imaging data in the first field after the detection signal is output. The detection means outputs each detection signal when detecting that the resistance value of the actuator is maintained within each predetermined range in order to notify that the lens is located at a position corresponding to each field. And the said control means is an imaging device of any one of Claims 2-4 which acquire the imaging data in each field, after each said detection signal is output. The detection means outputs a detection signal when it is detected that the resistance value of the actuator is maintained within a predetermined range so as to notify that the lens is located at the target position, and the control means The imaging device according to claim 2, wherein imaging data is acquired after the detection signal is output.

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