JP2014038212A - Program, imaging device and programmable logic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate an adjustment for each product relating to an offset upon offsetting a noise component from an output signal of a hall element, and to appropriately implement the offset of the noise component even when a current position of a shake correction lens coincides with a target position thereof.SOLUTION: By executing a program 241, a microcomputer 23 functions as a current position calculation part 231 and a difference calculation part 233. The current position calculation part 231 calculates a noise component of a position detection signal of a hall element 20 by multiplying a driving voltage acquired from a driving control part 22 by a coefficient k, subtracts the calculated noise component from a position detection signal and calculates a current position of a shake correction lens 10 from the subtraction result.

Description

  The present invention relates to a program executed by a computer used in a shake correction apparatus, an imaging apparatus including a computer that executes the program, a programmable logic device used in the shake correction apparatus, and an imaging apparatus including the programmable logic device. .

  An imaging device is known that includes a shake correction lens including a magnet, a drive unit that drives the shake correction lens, and a Hall element that detects the position of the shake correction lens using a magnetic field generated from the magnet of the shake correction lens (for example, Patent Document 1).

  With the downsizing of the imaging device, the Hall element detects not only the magnetic field generated from the magnet of the shake correction lens but also the magnetic field generated by the drive unit, and the position change of the shake correction lens may not be detected correctly. In Patent Document 1, this noise due to the magnetic field generated by the drive unit is canceled (noise cancellation) using an electronic circuit (magnetic component canceling unit) provided outside the microcomputer.

JP 2010-130860 A

  Position detection using a magnet and a hall element is easily affected by variations in characteristics of the magnet and the hall element and assembly accuracy, and may require fine adjustment for each product. However, with noise cancellation using an electronic circuit (magnetic component canceling unit) provided outside the microcomputer, it is difficult to make adjustments for each product.

  Further, in the invention of Patent Document 1, since an electronic circuit such as a magnetic component canceling unit is operated according to the difference between the target position of the shake correction lens and the current position, the target position and the current position of the shake correction lens are There is a problem in that the magnetic component canceling unit does not function when the values match.

  A program according to the present invention includes a shake correction lens including a magnet that generates a first magnetic field, a drive unit that drives the shake correction lens together with the magnet by generating a second magnetic field using a current flowing according to an input voltage, And a Hall element that detects the position of the shake correction lens by the first magnetic field and outputs a position detection signal, and a shake correction in which a noise signal due to the second magnetic field is superimposed on the position detection signal and output from the Hall element. The computer used in the apparatus multiplies the signal level of the input voltage by a coefficient to estimate the signal level of the noise signal, and the signal level of the noise signal estimated by the noise estimation unit from the output signal of the Hall element. A noise canceling unit that calculates a position detection signal by subtracting, and a difference that calculates a difference between the position of the shake correction lens corresponding to the position detection signal and the target position To function as a detection means.

  According to the present invention, since noise cancellation is performed using a program, adjustment for each product can be easily performed only by adjusting parameters of the program. In addition, since the noise component is canceled based on the drive voltage output to the voice coil, it corresponds to the case where the current position matches the target position.

It is a block block diagram of the imaging device by one embodiment of this invention. 1 is a block configuration diagram of a shake correction apparatus including a computer that executes a program according to an embodiment of the present invention. It is a figure which shows the characteristic of each component of a position detection signal. It is a flowchart regarding the process which the present position calculation part by one embodiment of this invention performs. It is a block diagram regarding the drive control system of the shake correction lens in the imaging device by one embodiment of the present invention. It is a flowchart regarding parameter adjustment for every product. It is a figure for demonstrating the parameter adjustment for every product. It is a figure for demonstrating the parameter adjustment for every product.

  FIG. 1 is a conceptual diagram of an imaging apparatus including an interchangeable lens incorporating a shake correction lens and a camera body. 1 is driven in two directions (x direction and y direction) orthogonal to the optical axis direction, and shakes in the pitching direction and the yawing direction are driven by the shake correction lens 10 incorporated in the interchangeable lens 12. to correct.

  A driving force for driving the shake correction lens 10 in each direction orthogonal to the optical axis direction is supplied from the driving unit 11. Although only one drive unit 11 is illustrated in FIG. 1, a plurality of drive units 11 are actually used for the shake correction lens 10. A voice coil motor (VCM) or the like is used for the drive unit 11.

  FIG. 2 is a block diagram of a shake correction apparatus 100 using the shake correction lens 10 of FIG. This shake correction apparatus 100 is provided in the imaging apparatus 1 of FIG. In the shake correction apparatus 100, the shake correction lens 10 includes a movable portion 10a to which a magnet 10b is attached. A magnetic field generated from the magnet 10 b is detected by the Hall element 20. The hall element 20 converts the detected magnetic field into an electric signal and outputs the electric signal to the microcomputer 23. The electric signal output from the hall element 20 is referred to as a position detection signal. The hall element 20 has an x direction and a y direction, and outputs a position detection signal in the x direction and a position detection signal in the y direction, respectively. The position detection signal is filtered by a low-pass filter (not shown) before being input to the microcomputer 23.

  The magnet 10b constitutes the above-described voice coil motor together with the voice coil 21. That is, the magnet 10b and the voice coil 21 constitute the drive unit 11 in FIG.

  The drive control unit 22 outputs a drive current to the voice coil 21. When a driving current is passed through the voice coil 21 in the magnetic field of the magnet 10b, a driving force is generated in a direction according to the Fleming left-hand rule, and the shake correction lens 10 is driven in that direction.

  When a drive current flows through the voice coil 21, a magnetic field is also generated from the voice coil 21 in a direction in accordance with the right hand rule. Therefore, the Hall element 20 detects not only the magnetic field generated from the magnet 10 b but also the magnetic field generated from the voice coil 21. The magnetic field generated from the voice coil 21 detected by the Hall element 20 becomes a noise component in the position detection signal. In the following description, the position detection signal excluding the noise component is referred to as a lens position component.

  FIG. 3A is a diagram illustrating the relationship between the position of the shake correction lens 10 in the x direction and the signal level of the lens position component of the position detection signal in the x direction. The lens position component of the position detection signal in the x direction has a signal level proportional to the position of the shake correction lens 10 in the x direction. The relationship between the position of the shake correction lens 10 in the y direction and the signal level of the lens position component of the position detection signal in the y direction is the same as in FIG.

  The shake correction lens 10 is urged by a spring (not shown) in the x direction and the y direction, and a neutral position is determined. The restoring force of the spring in the x direction (y direction) varies depending on the position of the shake correction lens 10 in the x direction (y direction). The driving force in the x direction (y direction) due to the driving current passed through the voice coil 21 opposes the restoring force of this spring. That is, in order to position the shake correction lens 10 at a predetermined position in the x direction (y direction), the driving force in the x direction (y direction) balances with the restoring force of the spring in the x direction (y direction) at that position. Need to be in a relationship. Therefore, the driving force in the x direction (y direction) is also proportional to the position of the shake correction lens 10 in the x direction (y direction), and the magnitude of the drive current that flows through the voice coil 21 to generate the driving force is also the shake correction lens 10. Is proportional to the position in the x direction (y direction). Since the strength of the magnetic field generated from the voice coil 21 is proportional to the drive current, the noise component of the position detection signal in the x direction (y direction) is also in the x direction of the shake correction lens 10 as shown in FIG. It is proportional to the position in the (y direction). Furthermore, the drive voltage applied by the drive control unit 22 to cause the drive current to flow through the voice coil 21 is also proportional to the position of the shake correction lens 10 in the x direction (y direction). Therefore, the drive voltage Va applied by the drive control unit 22 proportional to the position of the shake correction lens 10 in the x direction (y direction) and the noise component Vn of the position detection signal in the x direction (y direction) are Vn / The proportional relationship satisfies Va = k (constant).

  The microcomputer 23 in FIG. 2 estimates the noise component included in the position detection signal using the characteristic that the noise component of the position detection signal in the x direction (y direction) is proportional to the drive voltage applied by the drive control unit 22. Thus, the lens position component of the position detection signal is calculated.

  The microcomputer 23 executes a program 241 stored in the storage unit 24 such as a flash memory, and functions as at least a current position calculation unit 231, a target position calculation unit 232, and a difference calculation unit 233. The microcomputer 23 receives position detection signals in the x direction and the y direction from the hall element 20, and information related to the drive voltage from the drive control unit 22 in the x direction and the y direction.

  The current position calculation unit 231 calculates the current position of the shake correction lens in the x direction (y direction) based on the position detection signal input from the Hall element 20 and the information regarding the drive voltage input from the drive control unit 22. To do.

  FIG. 4 is a flowchart relating to processing executed by the current position calculation unit 231. The current position calculation unit 231 receives a position detection signal from the hall element 20 (step S400), and receives a drive voltage from the drive control unit 22 (step S401). The processing order of step S400 and step S401 may be the reverse order of the order shown in FIG. Moreover, the process of step S400 and step S401 may be performed in parallel.

  In step S402, the current position calculation unit 231 calculates the noise component Vn of the position detection signal by multiplying the drive voltage Va input from the Hall element 20 by the coefficient k described above. The noise component Vn of the position detection signal calculated in step S402 is substantially equivalent to the noise component of the actual position detection signal if the coefficient k is adjusted (calibrated) by a method described later.

  Note that the current position calculator 231 calculates the coefficient k for the drive voltage Va input from the Hall element 20, so that the drive voltage applied to the voice coil 21 does not increase k times.

  In step S403, the current position calculation unit 231 calculates the lens position component of the position detection signal by subtracting the noise component Vn calculated in step S402 from the input position detection signal.

  In step S404, the current position calculation unit 231 calculates the current position of the shake correction lens based on the lens position component calculated in step S403. After calculating the current position of the shake correction lens 10 in step S404, the current position calculation unit 231 proceeds to step S400 and repeats the process in FIG.

  A target position calculation unit 232 in FIG. 2 calculates a target position of the shake correction lens 10 for correcting the shake of the imaging apparatus 1 detected by a known shake detection process. The difference calculation unit 233 calculates the difference between the current position of the shake correction lens 10 calculated by the current position calculation unit 231 and the target position of the shake correction lens 10 calculated by the target position calculation unit 232.

  The difference between the current position and the target position of the shake correction lens 10 calculated by the difference calculation unit 233 is output to the drive control unit 22. The drive control unit 22 controls the drive voltage applied to the voice coil 21 based on the input difference. The drive control unit 22 changes the drive voltage by changing the duty ratio. As described above, the drive control unit 22 outputs the drive voltage applied to the voice coil 21 to the microcomputer 23.

  FIG. 5 is a block diagram relating to the drive control system of the shake correction lens 10 of the shake correction apparatus 100. In the block diagram of FIG. 5, the control target 50 corresponds to the shake correction lens 10. The target value of the control target 50 is the target position of the shake correction lens 10. Further, the current value of the control target 50 is the current position of the shake correction lens 10. A block diagram 58 surrounded by a broken line in FIG. 5 represents a position detection signal output from the Hall element 20. In the block diagram 58, both the lens position component and the noise component are represented as a block diagram.

  The difference between the current position and the target position of the shake correction lens 10 is calculated by the difference calculation unit 233 and input to the drive control unit 22 at a summing point 51 in FIG. The drive voltage of the drive control unit 22 is input to a take-off point 52 and branches into a drive system, a noise component system, and a noise cancellation system of the controlled object 50.

  The noise component system represents the noise component of the position detection signal due to the magnetic field generated from the voice coil 21, and a drive voltage amplified k times is added and input to the matching point 53. In addition point 53, the drive voltage amplified k times with respect to the lens position component of control object 50 is added as noise. This position detection signal is filtered by the low-pass filter 54 and input to the addition point 55.

  The noise cancellation system represents the noise component Vn calculated by the current position calculation unit 231 in step S402 in FIG. The drive voltage of the drive control unit 22 at the extraction point 52 is amplified k times in the noise canceling system, filtered by the digital low-pass filter 56 by the microcomputer 23, and input to the addition point 55.

  At the addition point 55, the signal filtered by the digital low-pass filter 56 is subtracted from the signal filtered by the low-pass filter 54 and input to the extraction point 57. At the extraction point 57, the signal subtraction result is converted to the current position of the shake correction lens 10 and fed back to the addition point 51.

  In order to appropriately calculate the lens position component of the position detection signal by subtraction at the addition point 55, the cut-off frequency fc of the digital low-pass filter 56 is adjusted to be the same as the cut-off frequency of the low-pass filter 54. There is a need. Further, it is necessary to appropriately calculate the coefficient k used by the current position calculation unit 231 to calculate the noise component in step S402. These values vary for each product of the imaging apparatus 1 and require adjustment.

  FIG. 6 is a flowchart regarding adjustment of the coefficient k and the cutoff frequency fc. The processing in FIG. 6 is executed by the microcomputer 23 when the imaging apparatus 1 is first activated or when the user gives an initial setting instruction for the imaging apparatus 1.

  In step S601, the microcomputer 23 applies the drive voltage Vd1 having a predetermined duty ratio d1 [%] to the drive control unit 22, and positions the shake correction lens 10 at the end of the movable region 70 as shown in FIG.

In step S602, the microcomputer 23 causes the drive control unit 22 to apply the drive voltage Vd2 having a duty ratio d2 [%] larger than the duty ratio d1. At this time, since the shake correction lens 10 is already positioned at the end of the movable region 70 in step S601, the lens position component of the position detection signal does not change. However, the noise component of the position detection signal changes as the drive current increases. Further, in step S602, the microcomputer 23 monitors a transient phenomenon of the drive voltage accompanying a change in the duty ratio, and measures a time constant τ shown in FIG. The time constant τ is the time until the drive voltage Vd1 reaches (1-1 / e) times the drive voltage Vd2. In other words, the time constant τ is the time until the drive voltage Vd1 reaches the following voltage V3.
V3 = Vd1 + 0.632 × (Vd2−Vd1)

In step S603, based on the duty ratio d1 and drive voltage Vd1 in step S601 and the duty ratio d2 and drive voltage Vd2 in step S602, the coefficient k is calculated by the following equation. The calculated coefficient k is stored in the storage unit 24.
k = (Vd2-Vd1) / (d2-d1)

In step S604, based on the time constant τ measured in step S602, the cutoff frequency fc is calculated by the following equation. The calculated cutoff frequency fc is stored in the storage unit 24.
fc = 1 / (2πτ)

  By doing in this way, adjustment of the coefficient k and the cut-off frequency fc for each product of the imaging apparatus 1 can be performed using a program.

According to the embodiment described above, the following operational effects can be obtained.
The imaging apparatus 1 according to the present invention detects a position of a shake correction lens 10 including a magnet 10b, a drive unit 11 including a magnet 10b and a voice coil 21, and a shake correction lens 10, and outputs a position detection signal. Hall element 20 is provided. Since the Hall element 20 also detects a magnetic field output from the voice coil 21 of the drive unit 11, the position detection signal includes a noise component and a lens position component. The microcomputer 23 of the imaging device 1 functions as the current position calculation unit 231 and the difference calculation unit 233 by executing the program 241 stored in the storage unit 24. The current position calculation unit 231 acquires information on the drive voltage from the drive control unit 22, adjusts the signal level of the drive voltage by k, and adjusts the signal to be substantially equal to the noise component. By subtracting from the output signal of the element, the noise component of the position detection signal is canceled. The current position calculation unit 231 calculates the current position of the shake correction lens 10 based on the lens position component of the position detection signal. The difference calculation unit 233 calculates a difference between the current position of the shake correction lens 10 calculated by the current position calculation unit 231 and the target position calculated by the target position calculation unit 232. Since the noise component of the position detection signal is canceled by the microcomputer 23 that executes the program 241 as described above, adjustment for each product is easy. Specifically, the imaging apparatus 1 can perform adjustment for each product by calculating the coefficient k by the process of FIG. Further, since the noise component is calculated based on the drive voltage output to the voice coil 21, it corresponds to the case where the current position matches the target position.

The embodiment described above can be implemented with the following modifications.
(Modification 1) In the above embodiment, the microcomputer 23 that executes the program 241 calculates the noise component by the voice coil 21 and cancels the noise component from the position detection signal. This method of canceling out the noise component can be applied not only to the noise caused by the voice coil 21, but also to the noise component generated from the shutter and the diaphragm drive unit of the imaging apparatus 1.

(Modification 2) The microcomputer 23 that executes the program 241 may be replaced with a programmable logic device (PLD: Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array).

  The embodiments and modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Further, the embodiments and modifications described above may be combined and executed as long as the features of the invention are not impaired.

DESCRIPTION OF SYMBOLS 1: Imaging device, 10: Shake correction lens, 10b: Magnet, 11: Drive part, 20: Hall element, 21: Voice coil, 22: Drive control part, 23: Microcomputer, 24: Storage part, 100: Shake correction apparatus , 231: Current position calculator, 232: Target position calculator, 233: Difference calculator, 241: Program, k: Coefficient, τ: Time constant

Claims (6)

A shake correction lens including a magnet for generating a first magnetic field;
A drive unit that generates a second magnetic field by a current flowing according to an input voltage and drives the shake correction lens together with the magnet;
A hall element that detects a position of the shake correction lens by the first magnetic field and outputs a position detection signal;
A computer used in a shake correction device in which a noise signal due to the second magnetic field is output from the Hall element in an overlapping manner with the position detection signal;
Noise estimating means for multiplying the signal level of the input voltage by a coefficient to estimate the signal level of the noise signal;
Noise canceling means for calculating the position detection signal by subtracting the signal level of the noise signal estimated by the noise estimation means from the output signal of the Hall element;
A program for functioning as difference calculation means for calculating a difference between a position of the shake correction lens corresponding to the position detection signal and a target position. The program according to claim 1,
The computer is further caused to function as coefficient calculation means for calculating the coefficient based on a change amount of an output signal of the Hall element when the shake correction lens is pressed against the end of the movable range using the drive unit. A program characterized by that. The program according to claim 2,
The output signal of the Hall element is input to the noise canceling means after passing through a low-pass filter having a predetermined cutoff frequency,
Cut-off frequency calculation means for calculating the cut-off frequency based on a transient phenomenon of the output signal of the Hall element when the computer is used to press the shake correction lens to the end of its movable range using the drive unit Let it work as
The noise estimation unit estimates the signal level of the noise signal by multiplying the input voltage by a coefficient and then performing a filtering process of the cutoff frequency calculated by the cutoff frequency calculation unit. A featured program.   An imaging device comprising a computer that executes the program according to claim 1. A shake correction lens including a magnet for generating a first magnetic field;
A drive unit that generates a second magnetic field by a current flowing according to an input voltage and drives the shake correction lens together with the magnet;
A hall element that detects a position of the shake correction lens by the first magnetic field and outputs a position detection signal;
A programmable logic device used in a shake correction device in which a noise signal due to the second magnetic field is output from the Hall element superimposed on the position detection signal,
Noise estimating means for multiplying the signal level of the input voltage by a coefficient to estimate the signal level of the noise signal;
Noise canceling means for calculating the position detection signal by subtracting the signal level of the noise signal estimated by the noise estimation means from the output signal of the Hall element;
A programmable logic device comprising: difference calculation means for calculating a difference between a position of the shake correction lens corresponding to the position detection signal and a target position.   An imaging device comprising the programmable logic device according to claim 5.

Images