JP2007017706A - Camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera module capable of restraining the resonant vibration of an actuator by appropriately setting a signal for driving the actuator. <P>SOLUTION: The camera module is equipped with: an imaging device 2; a lens 1 having an optical axis nearly perpendicular to the light receiving surface of the imaging device; the actuator 4 changing the relative positions of the lens and the imaging device; a command generating means 12 generating an operation command signal for the actuator; an actuator driving means 5 driving the actuator based on the operation command signal; and a damping filter part 14 having notch characteristic to damp a specified frequency component and damping the specified frequency component of the operation command signal and outputting it to the actuator driving part. The frequency component damped by the damping filter is set near the resonant frequency of the actuator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a camera module having a movable part.

A number of camera modules having movable parts have been proposed in order to realize autofocus, optical zoom, camera shake correction, or pixel shifting functions. As an actuator for moving the movable portion, for example, a stepping motor is used (see, for example, Patent Document 1), or the winding portion 14, the leaf spring 15 and the permanent magnet 16 as shown in FIG. There is an electromagnetic actuator that controls the amount of displacement by passing an electric current through. Furthermore, there are piezoelectric actuators, polymer actuators, electrostatic actuators or shape memory alloys, and in recent years, there are also small actuators in which these actuators are created using MEMS technology.
Japanese Patent Laid-Open No. 6-153592

  When a stepping motor is used as an actuator, the feed amount driven in one step of the motor must be set below the minimum pitch determined by the positioning accuracy. When performing high-precision positioning, the stepping motor will step out. If the pulse rate is set so as not to occur, the drive time becomes longer as the displacement increases, and the speed cannot be increased.

  On the other hand, when an electromagnetic actuator, a piezoelectric actuator, a polymer actuator, an electrostatic actuator, or a shape memory alloy actuator as shown in FIG. 2 is used, the actuator is further used depending on the resolution of the voltage output stage or when feedback control is performed. Positioning accuracy is determined by the position detection resolution, and high-precision positioning is possible. However, when the actuator is moved at a high speed, resonance vibration is generated by the spring element of the actuator as shown in FIG. 4, so that it takes time for the vibration to be attenuated to a permissible level or less and cannot be driven at high speed. 4A shows a waveform indicating the displacement x of the actuator, and FIG. 4B shows a waveform of the stepped voltage V applied to the actuator at this time.

  In other words, the actuator of a camera module with a moving part cannot realize positioning control that achieves both high speed and high accuracy, and cannot increase the speed of autofocus, optical zoom, camera shake correction, pixel shift function, etc. There's a problem.

  The present invention has been made to solve the conventional problems, and it is an object of the present invention to provide a camera module that can suppress resonance vibration of an actuator by appropriately setting a signal for driving the actuator. And

  In order to solve the above problem, a first camera module of the present invention includes an imaging device, a lens having an optical axis substantially perpendicular to a light receiving surface of the imaging device, and a relative position of the lens and the imaging device is changed. An actuator for generating an operation command signal for the actuator, an actuator driving unit for driving the actuator based on the operation command signal, and a notch characteristic for attenuating a specific frequency component, and the operation command signal And a damping filter unit that attenuates the specific frequency component and outputs the damping frequency component to the actuator driving unit, and the frequency component to be attenuated by the damping filter unit is set in the vicinity of the resonance frequency of the actuator. And

  The second camera module of the present invention includes a lens having an optical axis substantially perpendicular to a light receiving surface of the image sensor, an actuator for changing a relative position of the lens and the image sensor, and an operation command signal for the actuator. Command generating means for generating the actuator and actuator driving means for driving the actuator based on the operation command signal, and the operation command signal has a duration of a thrust applied to the actuator during the movement of the actuator. It is set to be an integral multiple of the period of vibration.

  ADVANTAGE OF THE INVENTION According to this invention, the camera module which can suppress the resonance vibration of an actuator can be provided by setting the signal which drives an actuator appropriately.

  According to the first and second camera modules of the present invention, when the relative position of the lens and the image sensor is changed, resonance vibration can be suppressed, and high speed and high accuracy of the actuator can be realized. That is, autofocus, optical zoom, camera shake correction, pixel shifting functions, and the like can be speeded up and increased in accuracy.

  In the first camera module of the present invention, the vibration suppression filter unit may include a low-pass filter. With this configuration, it is possible to reduce the fluctuation of the signal during the transient response of the command signal output from the vibration suppression filter unit. Therefore, it is possible to easily deal with restrictions such as the operating sound of the actuator.

  The damping filter unit may have a transfer function having an attenuation term, and a zero of the transfer function of the damping filter unit and a pole of the transfer function of the lens and the actuator may coincide with each other. . With this configuration, resonance vibration can be suppressed. In theory, if the transfer function zero of the damping filter unit and the pole of the transfer function of the actuator are completely matched, it is theoretically possible to eliminate the resonance vibration completely, but it is not necessary to match completely, and there is a zero near the pole. If there is, resonance vibration can be suppressed.

  Further, the vibration suppression filter unit compensates for misalignment so that the arrival point of the imaging element or the lens of the command signal to be output matches the arrival point of the imaging element or the lens of the operation command signal at a predetermined timing. It can also be configured to have means. With this configuration, it is possible to eliminate the positioning error due to the error of the vibration suppression filter unit.

  The damping filter unit may be configured by connecting a plurality of filters having different notch characteristics in series corresponding to a plurality of resonance frequencies of the actuator. With this configuration, resonance vibration can be suppressed for an actuator having a plurality of resonance frequencies.

  Further, the vibration suppression filter unit determines the arrival point of the imaging element or the lens of the command signal to be output at a predetermined timing with respect to each filter, and the arrival point of the imaging element or the lens of the operation command signal. It is also possible to employ a configuration having a position deviation compensating means for matching with the above.

  The damping filter unit may include a parameter setting unit that detects a resonance frequency of the actuator and determines a characteristic of the damping filter unit based on the detected resonance frequency. With this configuration, it is possible to cope with a resonance frequency shift caused by individual differences in actuators during mass production.

  In the second camera module of the present invention, the operation command signal input to the actuator driving unit by the command generating unit is the duration of the thrust when the actuator generates vibrations having a plurality of different frequencies. It is also possible to adopt a configuration in which the signal is an integral multiple of the period of all resonance vibrations to be suppressed.

  Further, it may be configured to further include parameter setting means for detecting the period of the resonance vibration of the actuator and determining the duration based on the detected period of the resonance vibration.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The camera module according to Embodiment 1 of the present invention uses a specific frequency component from a drive signal of an actuator to detect mechanical resonance vibration that occurs when a lens is moved at high speed by an actuator during autofocus (hereinafter abbreviated as AF). It suppresses by using the damping filter part to reduce.

  First, the overall configuration of the camera module according to Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration example of the camera module according to the present embodiment. Reference numeral 1 denotes a lens. Reference numeral 2 denotes an image pickup device constituted by a CCD or a CMOS image sensor that captures an image projected from the lens 1. An image sensor driving unit 3 receives the drive signal from the arithmetic circuit 6 and drives the image sensor 2. Reference numeral 4 denotes an actuator that changes the relative position between the lens 1 and the image sensor 2, and reference numeral 5 denotes an actuator driving unit (actuator driving means) that receives the command signal from the arithmetic circuit 6 and drives the actuator 4. The arithmetic circuit 6 is constituted by a DSP or a microcomputer, receives image data from the image sensor 2, gives a drive signal to the image sensor drive unit 3, and gives a command signal to the actuator drive unit 5 to control the entire camera module.

  The arithmetic circuit 6 includes an input / output unit 7 that performs external input / output control, a system control circuit 8 that controls the entire arithmetic circuit 6, an image processing unit 9 that processes image data, and an input from the image sensor 2. A signal input unit 10 that performs control, an AF calculation unit 11 that determines the position of the lens 1, a lens position command generation unit 12 (command generation unit) that generates a signal for controlling the position of the lens 1, and the signal And a vibration suppression filter unit 13 for filtering.

  The input / output unit 7 is connected to the system control unit 8 and is an interface for controlling input / output for command input from an external device, alarm output in the camera module, display of captured images, and storage of image data. is there. The system control unit 8 inputs signals to the image sensor 3 and the AF calculation unit 11, converts signals from the signal input unit 10 into image data, and controls the entire calculation circuit 6. The image processing unit 9 receives image data to be processed from the system control unit 8 and performs processing such as edge enhancement processing on the image data. The signal input unit 10 is an input device that takes in a signal from the image sensor 2 into the arithmetic circuit 6.

  The AF calculation unit 11 determines the position of the lens 1 that optimizes the focus state of the captured image. Based on the calculation result of the AF calculation unit 11, the lens position command creation unit 12 obtains a movement stroke in which the actuator 4 moves the lens 1 from the current position, and creates an operation command signal for moving the lens 1 along the movement stroke. And input to the vibration suppression filter unit 13. The damping filter unit 13 inputs a command signal from which the resonance frequency component of the actuator 4 is removed to the actuator driving unit 5 with respect to the operation command signal in order to suppress vibration generated when the lens 1 is moved by the actuator 4. .

  Next, the overall operation of the camera module according to the present embodiment will be described. The AF calculation unit 11 obtains a shift between the focus position and the lens 1 position, and inputs the focus adjustment signal to the lens position command creation unit 12. The lens position command creation unit 12 creates an operation command signal for moving the lens 1 based on the focus adjustment signal, and inputs the operation command signal to the vibration suppression filter unit 13. The damping filter unit 13 performs a filtering process on the operation command signal and inputs the filtered operation command signal to the actuator driving unit 5. The actuator driving unit 5 drives the actuator 4 to move the lens 1.

  Next, specific configurations and operating characteristics of the lens 1, the image sensor 2, and the actuator 4 will be described with reference to FIGS. FIG. 2 is a cross-sectional view illustrating a configuration example of the lens 1, the image sensor 2, and the actuator 4. The winding portion 14 is constituted by a winding capable of passing a current, a winding holder, and the like, and is fixed to the lens 1. The permanent magnet 16 is connected to the lens barrel 17, and the leaf spring 15 connects the winding portion 14 and the permanent magnet 16. By bending the leaf spring 15, the relative position of the winding portion 14 and the permanent magnet 16 can be made variable. The imaging element fixing substrate 18 is fixed to the lens barrel 17, and the imaging element 2 is fixed on the imaging element fixing substrate 18. As described above, the relative position between the lens 1 and the image sensor 2 is variable by the actuator 4 including the winding portion 14, the leaf spring 15, and the permanent magnet 16.

  In this actuator 4, the magnetic field formed by the current flowing through the winding portion 14 and the magnetic field formed by the permanent magnet 16 act to generate thrust, and the lens 1 and the winding portion 14 are moved in the left-right direction in FIG. 2. . At this time, when the leaf spring 15 is bent, a force (reaction force) corresponding to the relative position of the winding portion 14 and the permanent magnet 16 is generated in the direction opposite to the thrust. The actuator 4 stops at a position where the resultant force of the thrust and reaction force becomes zero (static characteristics). Therefore, the relative position between the lens 1 and the image sensor 2 can be controlled by controlling the voltage or current applied to the winding portion 14 of the actuator 4, thereby realizing the AF function.

  In order to obtain the dynamic characteristics of the actuator 4, FIG. 3 is a simplified mathematical model of FIG. This mathematical model has a configuration in which an object 19 having a mass m is joined by a spring 20 having a spring constant k and a damper 21 having a viscous friction coefficient D, and the x-axis is taken to the right in FIG. The mass m is substantially obtained from the masses of the lens 1 and the winding portion 14. The spring constant k can be obtained from the spring constant of the leaf spring 15. The viscous friction coefficient D can be obtained from the characteristics of the leaf spring 15 and the like.

The transfer function G1 (s) of the actuator 4 based on this mathematical model (including the lens 1; the same applies hereinafter)
G1 (s) = 1 / ((1 / ω _n ² ) · s ² + 2 · (D _n / ω _n ) · s + 1) (Expression 1)
It is expressed as Here, ω _n is the natural angular frequency of the actuator 4, ω _n = (k / m) ^1/2 , D _n is the damping coefficient of the actuator 4, and D _n = 1/2 · (D / (M · k) ^1/2 ).

FIG. 4A is a diagram showing the step response of the transfer function G1 (s), and FIG. 4B is a diagram showing the input (voltage applied to the winding section 14). Actuator 4, given a voltage V ₀ to the stepwise winding of the winding portion 14, moves from the reference position x0, residual vibration due to the influence of the leaf spring 15 around the equilibrium position x1 (hereinafter, referred to as resonant vibrations ). That is, the damping coefficient D _n of the actuator 4 is smaller than 1. Therefore, the image pickup device 2 waits for image capture until the amplitude of the resonance vibration is attenuated below the allowable value, which hinders speeding up of the AF function. In particular, in a camera module used in a portable device, the resonance vibration has a low frequency because the leaf spring 15 in FIG. 2 is thinned due to the demand for low power consumption and thinning, and the spring constant k becomes small. As a result, it is increasingly difficult to drive the actuator 4 at high speed.

  Next, the vibration suppression filter unit 13 will be described. The damping filter unit 13 is actually composed of a digital filter, but will be described as an analog filter for convenience of explanation. 5A and 5B are diagrams showing the frequency characteristics of the damping filter unit 13, where FIG. 5A shows the input / output gain and FIG. 5B shows the phase. As shown to (a), the damping filter part 13 has a notch characteristic in a specific frequency. Here, the notch characteristic refers to a characteristic that sharply and greatly reduces the input / output gain with respect to a specific frequency and frequencies in the vicinity thereof.

  By setting the specific frequency indicating the notch characteristic to the resonance frequency of the actuator 4 or a frequency in the vicinity thereof, the resonance frequency component is removed from the operation command signal created by the lens position command creation unit 12 or greatly reduced. Thereby, as shown in FIG. 6, the actuator 4 can be moved to the target position at high speed in a state where the resonance vibration is small. That is, the time for which the amplitude of the resonance vibration is attenuated to the allowable value or less is shortened, and the AF function can be speeded up.

  Next, a specific realization method for matching the notch characteristics to the resonance frequency of the actuator 4 will be described using (Expression 2) and (Expression 3). (Expression 2) shows a transfer function G2 (s) of the vibration suppression filter unit 13 using the Laplace operator s.

G2 (s) = ((1 / ω _r ² ) · s ² +1) / ((1 / ω _f ² ) · s ² + 2 · (D _f / ω _f ) · s + 1) (Expression 2)

Here, ω _r is a set angular frequency, ω _f is a filter angular frequency, and D _f is a filter attenuation constant. The transfer function G2 (s) in the frequency response G2 (j [omega]), omega is next gain 0 in the case of setting angular frequency omega _r, are designed to molecules is a second order filter. Here, j is an imaginary unit. That is, in the transfer function G2 (s), the numerator removes the frequency component of the set angular frequency ω _r , in other words, the frequency ω _r / (2π) to suppress the resonance vibration of the actuator 4, and the denominator is the damping filter unit 13. It is designed to suppress steep fluctuations in the output value.

FIG. 7A shows an operation command signal that is an output of the lens position command generation unit 12, and FIGS. 7B and 7C show a command signal that is an output of the vibration suppression filter unit 13 at this time. . FIG. 7B shows a case where ω _f of the transfer function G2 (s) is high, and FIG. 7C shows a case where ω _f is low. When the filter angular frequency ω _f is lowered, the maximum value of the output of the damping filter unit 13 can be reduced. Therefore, as shown in (Equation 2), by setting ω _f of the transfer function G2 (s) of the damping filter unit 13 to be low, a low-pass filter is included. By changing ω _f , it becomes easy to adjust the maximum value of the output of the damping filter unit 13 according to the upper limit of the output voltage range or the restrictions such as the operation sound when the actuator 4 moves.

The filter attenuation constant D _f is set to a value of 1 or more so that the gain does not become 1 or more in the entire frequency region when the numerator of the transfer function G2 (s) is 1, that is, resonance vibration does not occur. It is desirable to set. Further, in order to quickly move the lens 1 to the designated position, it is more desirable that the filter attenuation constant D _f is close to 1.

  Next, as shown in (Expression 3), a transfer function G3 (s) of the damping filter unit 13 in which an attenuation term (first order term of the Laplace operator s) is inserted into the numerator of (Expression 2) is shown.

G3 (s) = ((1 / ω r 2) · s 2 +2 · (D r / ω r) · s + 1) / ((1 / ω f 2) · s 2 +2 · (D f / ω f) · s + 1) (Formula 3)

Here, _Dr is a set attenuation constant. FIG. 8 is a diagram illustrating the displacement x of the actuator 4 by step input when the parameters are appropriately set when the transfer function of the damping filter unit 13 is G3 (s). The output of the lens position command creating unit 12 input to the damping filter unit 13 is the same as that in FIG. 7A, and the attenuation term 2 · (D _r / ω _r ) · is added to the numerator of the transfer function G3 (s). It can be seen that the resonance vibration can be completely removed by inserting s. At this time, the command signal from the damping filter unit 13 is almost the same as that in FIG. Note that the scales of the vertical and horizontal axes in FIG. 8 are the same as the response waveforms in FIGS. 4 and 6. In addition, the scales of the vertical axis and the horizontal axis of each of FIGS. 7A, 7B, and 7C are the same, and in order to make the output waveform of the damping filter unit 13 easier to see, FIG. The display is larger than 8.

Next, with respect to the transfer function G2 (s), the principle that resonance vibration can be completely removed by inserting a damping term into the numerator of the transfer function G3 (s) will be described with reference to the polar plane of FIG. explain. FIG. 9 is a polar plane in which the horizontal axis is the real axis and the vertical axis is the imaginary axis, ◯ indicates the zero of the transfer function of the damping filter unit 13, and × indicates the pole of the transfer function in the model of the actuator 4. The transfer function G1 of the actuator 4 (s), from 1> _{D n,}
G1 (s) = 1 / ((1 / ω _n ² ) · s ² + 2 · (D _n / ω _n ) · s + 1)
_{= 1 / (s + (D} n · ω n + (1-D n 2) -1/2 ω n j)) · (s + (D n · ω n - (1-D n 2) -1/2 ω _n j)
Thus, the poles are obtained as -D _n · ω _n + (1-D _n ² ) ^1/2 · ω _n j, -D _n · ω _n- (1-D _n ² ) ^1/2 · ω _n j It is done. Therefore, as shown in FIG. 9, the poles (resonance poles) exist symmetrically with the real axis in the left half plane on the polar plane. Here, by moving this pole on the real axis or performing pole-zero cancellation by the zero point as shown in FIG. 9, the resonance vibration can be theoretically completely eliminated.

In the present invention, a zero point is provided in the transfer function of the damping filter unit 13, and pole-zero cancellation is performed by making it coincide with the pole of the transfer function of the actuator 4, so that the resonance vibration is theoretically completely removed. Even if the zero point does not completely coincide with the pole, if it is arranged in the vicinity thereof, a great vibration suppressing effect is produced. Case without the molecule to attenuation term of (formula 3), the zero point that is (Formula 2) In the transfer function G2 (s), varying the set angular frequency omega _r moves on the imaginary axis. Therefore, when the imaginary part of the zero point and the imaginary part of the pole in the transfer function of the actuator 4 are the same, the distance between the zero point and the pole is the shortest, and the vibration caused by the pole is greatly reduced (FIG. 6 response waveform). However, unless this pole is on the imaginary axis, pole-zero cancellation cannot be performed, and the resonance vibration cannot be completely removed. By inserting the attenuation term 2 · (D _r / ω _r ) · s as in (Expression 3) and appropriately setting D _r and ω _r , the damping filter unit 13 can be set to an arbitrary point on the polar plane. A zero can be placed in Therefore, by making the zero point coincide with the pole as shown in FIG. 9, complete vibration removal by pole-zero cancellation can be performed as in the response waveform shown in FIG.

  Next, the position shift compensation function of the vibration suppression filter unit 13 will be described. The damping filter unit 13 is a digital filter having an input / output relationship obtained from (Expression 2) or (Expression 3) by performing bilinear transformation or the like. The relational expression of the input / output of the damping filter unit 13 which is a digital filter can be expressed as shown in (Expression 4) by using the bilinear transformation.

y (n) = K1 * z (n) + K2 * z (n-1) + K3 * z (n-2) + K4 * y (n-1) + K5 * y (n-2) (Formula 4)
Here, z is an input value of the damping filter unit 13, and y is an output value. The subscript n indicates the current time in the time series, n-1 indicates the time immediately before the current time series, and n-2 indicates the time two times before the current time series. The coefficients K1, K2, K3, K4, and K5 are parameters that determine the characteristics of the vibration suppression filter unit 13 in (Equation 4), and are set angular frequency ω _r , set attenuation constant D _r , filter angular frequency ω _f , and filter attenuation. Using the constant D _f and the sampling period T _s ,
K1 = (4 / (ω _r ² · T _s ² ) + 4 · D _r / (ω _r · T _s ) +1) / K 0
K2 = (− 8 / (ω _r ² · T _s ² ) +2) / K0
_{K3 = (4 / (ω r} 2 · T s 2) -4 · D r / (ω r · T s) +1) / K0
K4 = (8 / (ω _f ² · T _s ² ) −2) / K0
K5 = (− 4 / (ω _f ² · T _s ² ) + 4 · D _f / (ω _f · T _s ) −1) / K 0
K0 = 4 / (ω _f ² · T _s ² ) + 4 · D _f / (ω _f · T _s ) +1
Can be expressed as

  When the digital filter of the damping filter unit 13 is created in this way, the actuator 4 of the signal input to the damping filter unit 13 arrives due to problems in the principle of the IIR filter, rounding error, etc. There is a case where the power position and the output signal are different from each other. In order to avoid this displacement, the lens position command generator 12 (position displacement compensation means), as shown in FIG. 10, starts the operation time point A (or operation command) of the operation command signal input to the damping filter unit 13. The arrival position of the output signal of the damping filter unit 13 is matched with the arrival position of the input signal at a time point B1 after a predetermined time T from the signal end time). In addition, the dotted line of FIG. 10 has shown the input waveform of the damping filter part 13, and the continuous line has shown the output waveform.

  Alternatively, as shown in FIG. 11, the output arrival position of the vibration suppression filter unit 13 may be matched with the input arrival position at a point B2 when the output of the vibration suppression filter unit 13 enters a predetermined range indicated by a dotted line. . At this time, if the input and output values are suddenly matched at the time point B2, vibration may occur. Therefore, it is better to match them step by step.

Next, parameter setting of the vibration suppression filter unit 13 will be described. If the difference between the set angular frequency omega _r of the resonant angular frequency and the damping filter portion 13 of the actuator 4 is large, the resonance vibration of the actuator 4 is increased. When the camera module is mass-produced, the resonance frequency of the actuator 4 may be different due to individual differences. Therefore, it is necessary to measure the resonance frequency for each individual and set the parameters of the damping filter unit 13 based on the result. There is a case. By setting parameters for each camera module, it is possible to position the lens with high accuracy at high speed without any resonance vibration at all, and to realize an AF function with high accuracy at high speed.

  FIG. 12 is a block diagram illustrating a configuration for setting parameters of the vibration suppression filter unit 13. The command creation unit 22 outputs a command signal that easily excites resonance vibration of the actuator 4 such as a step command. A signal is input from the command creating unit 22 to the actuator driving unit 5, and the actuator driving unit 5 moves the lens 1 via the actuator 4. The detection unit 23 includes a displacement sensor that observes the displacement of the lens 1 or the actuator 4 or the vicinity thereof, or a sensor that observes the current or voltage of the winding of the actuator 4. The frequency calculation unit 24 (parameter setting unit) is connected to the detection unit 23 and the vibration suppression filter unit 13 and calculates a resonance frequency based on a signal from the detection unit 23.

  The actuator 4 and the lens 1 are vibrated by the signal created by the command creation unit 22. The detection unit 23 detects the vibration of the lens 1 or the actuator 4. The frequency calculation unit 24 calculates the resonance frequency based on the signal from the detection unit 23.

  As a method of calculating the resonance frequency of the frequency calculation unit 24, a vibration component is extracted from a signal including the vibration component input from the detection unit 23 using a bandpass filter or the like, and the resonance frequency is calculated from an interval at which the waveform value is zero-crossed. , A method for detecting a peak value of vibration of a signal including a vibration component input from the detection unit 23, a method for determining a resonance frequency from a time interval of the peak value, and a signal including a vibration component input from the detection unit 23 For example, there is a method of performing a Fourier transform and obtaining a resonance frequency from the result.

The damping filter unit 13 sets the set angular frequency omega _r multiplied by 2π to the resonance frequency calculated by the frequency calculating unit 24. When the set damping constant _Dr is also set, the set damping constant is set according to the attenuation of the peak value of the resonance vibration detected from the detection unit 23 or according to the calculated value of the resonance frequency component by the Fourier transform described above. _Obtain and set _Dr. Also, If the filter angle wavenumber omega _f set in accordance with the set angular frequency omega _r set by the above, the table defining the correspondence between the set angular frequency omega _r and the filter angular frequency omega _f or set angular frequency omega _The filter angular frequency ω _f is obtained and set using a relational expression between _r and the filter angular frequency ω _f . As described above, the parameters of the vibration suppression filter unit 13 are set.

  The detection unit 23 and the frequency calculation unit 24 may be built in the camera module or may be configured as separate devices.

  In the camera module according to the present embodiment, mechanical resonance vibration generated when the lens 1 is moved at high speed by the actuator 4 during AF, and the resonance frequency component of the actuator 4 from the command signal input to the actuator driving unit 5 is used. The vibration suppression filter unit 13 to be reduced or removed is inserted to greatly suppress or eliminate. Therefore, the lens 1 can be positioned at high speed and with high accuracy, and a high speed and high accuracy AF function can be realized. Further, even during mass production in which individual variations occur, by measuring the resonance frequency and setting parameters for each individual, a high-speed and highly accurate AF function can be realized for all individuals.

  The actuator driving unit 5 may perform open loop control or closed loop control when driving the actuator 4 in response to a command signal from the vibration suppression filter unit 13.

  In addition, when the actuator driving unit 5 is configured by closed loop control, vibration due to the design of the closed loop system may occur. However, according to the present embodiment, this vibration can be suppressed by the same principle and the same parameter setting method as the above-described resonance vibration.

  Further, the image sensor driving unit 3 and the actuator driving unit 5 may be included in the arithmetic circuit 6.

Further, when there are a plurality of resonance frequencies of the actuator 4, the same effect can be obtained by adopting a configuration in which the damping filter unit 13 has a transfer function obtained by combining a plurality of the above-described (Equation 2) or (Equation 3) in series. be able to. FIG. 13 shows a block configuration of the vibration suppression filter unit 13 at this time. The block 1 in FIG. 13 suppresses the resonance vibration at the angular frequency ω _r1 , and the block 2 suppresses the resonance vibration at the angular frequency ω _r2 . Similarly, for other blocks, an angular frequency to be suppressed for each block is set.

  The positional deviation compensation at this time is performed after the elapse of the predetermined time T as described above or when the output of each block enters the predetermined range. At this time, it is possible to reduce the amount of displacement at the time of misalignment compensation by performing the misalignment compensation for each block of FIG. 13 instead of the input and output of the vibration suppression filter unit 13, and a rapid command due to misalignment compensation It becomes easy to avoid the occurrence of vibration due to the fluctuation of the signal (voltage value).

  FIG. 14 is a block diagram of a camera module that performs optical zoom. The difference is that the AF calculation unit 11 of the camera module according to the present embodiment is replaced with an optical zoom calculation unit 25, and other configurations are the same. The optical zoom calculator 25 determines an optimal lens position based on a command from the user.

  In the present embodiment, the high speed and high accuracy of the AF function has been described. With respect to the optical zoom function, the relative position between the lens 1 and the image sensor 2 can be determined with high speed and high accuracy in the configuration of FIG. Are the same. Therefore, by replacing the AF calculation unit 11 of the camera module according to the present embodiment with the optical zoom calculation unit 25, a high-speed and high-precision optical zoom function can be realized. Further, even during mass production where individual variation occurs, a high-speed and high-precision optical zoom function can be realized for all individuals by measuring the resonance frequency and setting parameters as in the AF function.

  FIG. 15 is a block diagram of a camera module having an optical camera shake correction function. The other difference is that the AF calculation unit 11 of the camera module according to the present embodiment is replaced with a camera shake correction calculation unit 26. The camera shake correction calculation unit 26 determines the optimum lens 1 position based on acceleration information from a gyro sensor or the like, or acceleration information calculated from a captured image taken at different times. In the AF function and the optical zoom function, the lens 1 moves in a direction perpendicular to the imaging surface of the image sensor, but in the case of camera shake correction, the lens 1 moves in a direction parallel to the imaging surface of the image sensor. However, the point which suppresses resonance vibration is the same.

  The camera shake correction calculation unit 26 receives acceleration information related to camera shake from a gyro sensor or the like, and generates a signal for performing camera shake correction. As in the AF function, the lens position creation unit 12 creates a signal indicating the reference position of the lens 1, the vibration suppression filter unit 13 suppresses the resonance angular frequency, and the actuator 4 moves the lens 1 to correct camera shake. To do.

  Even during mass production in which individual variations occur, a high-precision optical camera shake correction function can be realized for all individuals by measuring the resonance frequency and setting parameters as in the AF function.

  FIG. 16 is a block diagram of a camera module having a pixel shifting function. The difference is that the AF calculation unit 11 of the camera module according to the present embodiment is replaced with a pixel shift calculation unit 27, and other configurations are the same. The pixel shift calculation unit 27 determines an optimal lens position based on image capturing timing information of the image sensor 2 and the like. By positioning the lens 1 at high speed and with high accuracy, a high-speed and high-precision pixel shifting function can be realized. Also in this case, the lens 1 moves in a direction parallel to the imaging surface of the imaging device. Further, even during mass production in which individual variation occurs, a high-speed and high-accuracy pixel shifting function can be realized for all individuals by measuring the resonance frequency and setting parameters as in the camera shake correction function.

  The configuration of the actuator 4 is not limited to the voice coil motor as shown in FIG. 2, but other mechanical actuators such as electromagnetic actuators, electrostatic actuators, piezoelectric actuators, polymer actuators, and shape memory alloys generate mechanical resonance vibrations. It can be applied to all types of actuators.

  For functions such as the camera shake correction function and the pixel shifting function, the actuator 4 includes a plurality of actuators. Even in this case, the vibration suppression filter unit 13 can be configured to remove the resonance frequency of each actuator 4 to suppress the resonance vibration.

  In the camera module of the present embodiment, the lens 1 is moved by the actuator 4, but the image sensor 2 is moved instead of the lens 1 to change the relative position of the lens 1 and the image sensor 2. You can also

(Embodiment 2)
In the camera module according to Embodiment 2 of the present invention, the mechanical resonance vibration generated when the lens is moved at high speed by the actuator during AF, and the thrust duration applied to the actuator during movement is made an integral multiple of the period of the resonance vibration. It suppresses by doing.

  FIG. 17 is a block diagram illustrating a configuration example of the camera module according to the present embodiment. Reference numeral 206 denotes an arithmetic circuit having a DSP, a microcomputer, and the like. Reference numeral 212 denotes a lens position command generating unit (command generating means) that generates an operation command signal for controlling the position of the lens 1. Other configurations of the camera module according to the present embodiment are the same as those of the first embodiment except that the vibration suppression filter unit 13 is not provided. Based on the displacement amount of the actuator 4 input from the AF calculation unit 11, the lens position command generation unit 212 outputs an operation command signal for moving the actuator 4 to the actuator drive unit 5 as shown in FIG. 18.

  In the present embodiment, as in the first embodiment, a case where the actuator 4 is realized by the electromagnetic actuator shown in FIG. 2 will be described as an example. Particularly in camera modules used in portable devices, the resonance frequency becomes lower due to the reduction in the thickness of the leaf spring 15 due to the demand for low power consumption and thinning. Driving has become difficult.

  FIG. 18 is a diagram illustrating a drive signal input to the actuator 4. The horizontal axis represents time, and the vertical axis represents the position of the actuator 4 or a voltage value corresponding to the position. The lens position command creating unit 212 sets the time for the actuator 4 to change from the position C to the position D (thrust continuation time Ta when the actuator moves) to an integer multiple of the resonance vibration period Tv of the actuator 4.

  FIG. 19 is a diagram showing the position x of the actuator 4, (a) is a response when the thrust duration Ta when the actuator 4 is moved is an integral multiple of the vibration period Tv, and (b) is a response when the actuator 4 is moved. The response when the thrust duration time Ta is not an integral multiple of the vibration period Tv is shown. FIG. 19A and FIG. 19B are the same scale on the horizontal axis and the vertical axis. Therefore, it can be seen that the resonance vibration is greatly reduced when the thrust continuation time Ta during the movement of the actuator 4 is an integral multiple of the vibration period Tv.

  Next, a method for setting Ta when there are a plurality of resonance frequencies of the actuator 4 will be described. For example, when the actuator 4 has two resonance frequencies and the vibration periods are Tv1 and Tv2, respectively, the thrust continuation time Ta when the actuator 4 is moved is an integral multiple of both the vibration period Tv1 and the vibration period Tv2. Set. As a numerical example, when the vibration period Tv1 is 10 ms and the vibration period Tv2 is 15 ms, if the thrust continuation time Ta is 30 ms, it becomes an integral multiple of both Tv1 and Tv2, so the vibration periods Tv1 and Tv2 Both vibrations can be suppressed. Even when there are three or more resonance frequencies, it is possible to suppress all resonance vibrations to be suppressed by setting the thrust continuation time Ta to be an integral multiple of all the vibration periods to be suppressed.

  Next, parameter setting of the lens position command creation unit 212 will be described. When the deviation between the vibration cycle Tv and the thrust duration time Ta of the actuator 4 created by the lens position command creation unit 212 is large, the vibration of the actuator 4 becomes large. When the camera module is mass-produced, the resonance frequency of the actuator 4 may be different due to individual differences. Therefore, the period of resonance vibration is measured for each individual, and the thrust duration time Ta that is a parameter of the lens position command creation unit 212 is set. As a result, it is possible to perform high-speed and high-accuracy lens positioning with no or small resonance vibration and high-speed and high-accuracy AF function for all individuals.

  FIG. 20 is a block diagram showing a configuration for setting the parameters of the lens position command creation unit 212. In contrast to the parameter setting method shown in FIG. 12 of the first embodiment, the frequency calculation unit 24 and the vibration suppression filter unit 13 are changed to a period calculation unit 224 and a lens position command creation unit 212. Other configurations are the same as those in FIG. The period calculation unit 224 calculates the period of resonance vibration based on the signal from the detection unit 23.

  As a method of calculating the period of resonance vibration in the period calculation unit 224, a vibration component is extracted from a signal including a vibration component input from the detection unit 23 using a bandpass filter or the like, and the waveform value is based on an interval at which zero crossing occurs. A method for obtaining the period of resonance vibration, a method for detecting the peak value of resonance vibration of a signal including a vibration component input from the detection unit 23, and a method for obtaining the period of resonance vibration based on the time interval of the peak value. There is a method of performing Fourier transform on a signal including an input resonance vibration component and obtaining a resonance vibration period from the result. The lens position command creation unit 212 sets the thrust continuation time Ta when the actuator 4 moves based on the resonance vibration period calculated by the period calculation unit 224. The detection unit 23 and the cycle calculation unit 224 may be built in the camera module or may be configured as separate devices.

  As a parameter setting method, first, the command creation unit 22 outputs a command signal that easily excites resonance vibration to the actuator 4 to cause the actuator 4 to resonate.

  Next, the detection unit 23 detects the vibration and sends the detected signal to the period calculation unit 224. The period calculation unit 224 obtains the period of resonance vibration from the detected signal. The lens position command creation unit 212 sets the thrust continuation time Ta of the actuator 4 based on the resonance vibration cycle calculated by the cycle calculation unit 224. In this way, the parameter setting of the lens position command creation unit 212 is performed.

  With the configuration as described above, the camera module according to Embodiment 2 of the present invention resonates the mechanical resonance vibration generated when the lens 1 is moved at high speed by the actuator 4 during AF, and the duration of the thrust applied to the actuator 4 is resonated. Suppressing by making it an integral multiple of the period of vibration. Accordingly, high-speed and high-precision lens positioning is possible, and a high-speed and high-precision AF function can be realized. Further, even during mass production where individual variation occurs, it is possible to realize a high-speed and high-precision AF function for all individuals by measuring the period of resonance vibration and setting parameters.

  The actuator drive unit 5 may use either open loop control or closed loop control when driving the actuator 4 in response to a command signal from the lens position command creation unit 212.

  Further, the image sensor driving unit 3 and the actuator driving unit 5 may be included in the arithmetic circuit 206.

  In the present embodiment, the high speed and high accuracy of the AF function and the parameter setting at the time of mass production are described. However, the present invention is not limited to the AF function.

  FIG. 21 is a block diagram of a camera module having an optical zoom function. In contrast to the camera module in FIG. 17, the AF calculation unit 11 is changed to an optical zoom calculation unit 25. The optical zoom calculator 25 determines an optimal lens position based on a command from the user. With this configuration, a high-speed and high-precision optical zoom function can be realized by positioning the relative position between the lens 1 and the image sensor 2 with high speed and high accuracy. Also, in mass production where individual variation occurs, a high-speed and high-precision optical zoom function can be realized for all individuals by measuring the resonance period and setting parameters as in the AF function.

  FIG. 22 is a block diagram of a camera module having an optical camera shake correction function. In contrast to the camera module in FIG. 17, the AF calculation unit 11 is changed to a camera shake correction calculation unit 26. The camera shake correction calculation unit 26 determines an optimum lens position based on acceleration information from a gyro sensor or the like, acceleration information calculated from captured images taken at different times, and the like. In the AF function and the optical zoom function, the lens 1 moves in a direction perpendicular to the imaging surface of the image sensor 2. In this case, the lens 1 moves in a direction parallel to the imaging surface of the image sensor 2. However, the same effect can be obtained by performing the same control as in the case of moving in the vertical direction. Even during mass production in which individual variations occur, as in the AF function, a highly accurate optical image stabilization function can be realized for all individuals by measuring the period of resonance vibration and setting parameters.

  FIG. 23 is a block diagram of a camera module having a pixel shifting function. In contrast to the camera module in FIG. 17, the AF calculation unit 11 is changed to a pixel shift calculation unit 27. The pixel shift calculation unit 27 determines the optimum position of the lens 1 based on the image capturing timing information of the image sensor 2 and the like. With this configuration, even with respect to a pixel shifting function for the purpose of increasing the number of pixels in a captured image, it is possible to realize a high-speed and high-accuracy pixel shifting function by positioning the lens 1 at high speed and high accuracy. it can. Even in the case of the pixel shifting function, the lens 1 moves in the direction parallel to the imaging surface of the imaging device, but can be controlled in the same way as in the case of the optical camera shake correction function. Even during mass production where individual variation occurs, a high-speed and high-accuracy pixel shifting function can be realized for all individuals by measuring the period of resonance vibration and setting parameters as in the AF function.

  In addition, the configuration of the actuator 4 generates mechanical resonance vibration not only by the voice coil motor as shown in FIG. 2, but also by other electromagnetic actuators, electrostatic actuators, piezoelectric actuators, polymer actuators, shape memory alloys, etc. It can be applied to all types of actuators.

  Further, the actuator 4 may be composed of a plurality of actuators depending on the function.

  Here, FIG. 24 shows an example in which the actuator 4 is configured by an electromagnetic actuator of a different type from that in FIG. The same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 28 denotes a motor that generates rotational torque in the rotational direction with the x axis as a rotational axis, 29 is a ball screw that has grooves and converts the rotational torque of the motor 28 into thrust in the x direction, and 30 is a guide. Reference numeral 31 denotes a holder that fixes the lens 1 and slides the guide 30 in the x direction. Reference numeral 32 denotes a holder that fixes the lens 1 and receives thrust in the x direction from the ball screw 29. The rotational torque of the motor 28 is converted into thrust in the x-axis direction of the holder 32, and the lens 1 fixed to the holder 32 is displaced in the x-axis direction. The guide 30 and the holder 31 are configured for the purpose of keeping the optical axis and the imaging surface of the imaging element 2 perpendicular to each other even when the lens 1 is displaced.

  FIG. 25 is a diagram illustrating the displacement of the lens 1 during autofocus, and FIG. 26 is a diagram illustrating the torque associated with the lens 1 at that time. In the actuator of this configuration, when the lens 1 is displaced from E to F as shown in FIG. 25 in the x-axis direction, acceleration thrust and deceleration thrust are required as shown in FIG. In this case, if the thrust continuation time (acceleration) Ta1 and the thrust continuation time (deceleration) Ta2 of FIG.

  In FIGS. 17, 21, 22, and 23, the lens 1 is driven by the actuator 4, but it goes without saying that the image sensor 2 may be driven instead of the lens 1.

  The present invention is a camera module that suppresses resonance vibration of an actuator and can change the relative position of a lens and a light receiving element at high speed and high accuracy. It can be used in the field of cameras that require high-speed positioning using the camera.

1 is a block diagram showing a configuration of a camera module according to Embodiment 1 of the present invention. Sectional drawing which shows the structure of the actuator and lens of the camera module which concern on Embodiment 1 and 2 of this invention. The figure which shows the model which simplified the actuator and lens of the camera module which concerns on Embodiment 1 of this invention. The figure which shows (a) step response and (b) step input by the mathematical model of the actuator and lens of a camera module same as the above. The figure which shows the (a) frequency characteristic of the damping filter part of a camera module same as the above, and the example of (b) phase characteristic. The figure which shows the response of the actuator of the camera module same as above The figure which shows the operation command signal input into the (a) damping filter part of a camera module same as the above, and the command signal output from (b) (c) damping filter part. The figure which shows the response of the actuator of the camera module same as above The figure for demonstrating the vibration suppression principle of a camera module same as the above Explanatory drawing of the positional deviation compensation function of the camera module Explanatory drawing of the positional deviation compensation function of the camera module The block diagram which shows the configuration which performs the parameter setting of the same camera module The block diagram which shows the vibration suppression filter part which suppresses the some resonance frequency of a camera module same as the above. The block diagram which shows the structure which has an optical zoom function of a camera module same as the above. The block diagram which shows the structure which has the camera-shake correction function of a camera module same as the above. The block diagram which shows the structure which has a pixel shift function of a camera module same as the above The block diagram which shows the structure of the camera module which concerns on Embodiment 2 of this invention. The figure which shows the movement process of the actuator which the lens position command creation part of a camera module same as the above creates (A) When the thrust duration of the camera module is set to a constant multiple of the resonance period of the actuator, (b) a diagram showing the response of the lens position when it is not a constant multiple The block diagram which shows the configuration which performs the parameter setting of the same camera module Block diagram showing the configuration of the optical zoom function of the camera module The block diagram which shows the constitution of the camera shake correction function of the same camera module Block diagram showing the configuration of the pixel shifting function of the camera module Configuration diagram showing the configuration of the actuator and lens of the camera module The figure which shows the displacement of the lens 1 at the time of autofocus of a camera module same as the above. The figure which shows the thrust with respect to the actuator at the time of autofocus of a camera module same as the above

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Image pick-up element 3 Image pick-up element drive part 4 Actuator 5 Actuator drive part 6,206 Arithmetic circuit 7 Input / output part 8 System control part 9 Image processing part 10 Signal input part 11 AF arithmetic part 12, 212 Lens position command creation part 13 Damping filter section 14 Winding section 15 Plate spring 16 Permanent magnet 17 Lens barrel 18 Imaging element fixed substrate 19 Mass 20 Spring 21 Damper 22 Command creation section 23 Detection section 24 Frequency calculation section 25 Optical zoom calculation section 26 Camera shake correction calculation section 27 Pixel shift calculation unit 28 Motor 29 Ball screw 30 Guide 31, 32 Holder 224 Period calculation unit

Claims (10)

An image sensor;
A lens having an optical axis substantially perpendicular to the light receiving surface of the image sensor;
An actuator for changing a relative position of the lens and the imaging device;
Command creating means for creating an operation command signal of the actuator;
Actuator driving means for driving the actuator based on the operation command signal;
A notch characteristic for attenuating a specific frequency component, and a damping filter unit that attenuates the specific frequency component of the operation command signal and outputs the attenuated specific frequency component to the actuator drive unit,
The camera module according to claim 1, wherein a frequency component to be attenuated by the vibration suppression filter unit is set in the vicinity of a resonance frequency of the actuator.   The camera module according to claim 1, wherein the vibration suppression filter unit includes a low-pass filter.   3. The camera according to claim 1, wherein the damping filter unit has an attenuation term in a transfer function, and a zero of the transfer function of the damping filter unit matches a pole of the transfer function of the lens and the actuator. module.   The vibration suppression filter unit includes a positional deviation compensation unit that matches the arrival point of the imaging element or the lens of the command signal to be output with the arrival point of the imaging element or the lens of the operation command signal at a predetermined timing. The camera module according to any one of claims 1 to 3.   The camera module according to any one of claims 1 to 3, wherein the vibration suppression filter unit is configured by connecting a plurality of filters having different notch characteristics corresponding to a plurality of resonance frequencies of the actuator in series. .   The damping filter unit matches the arrival point of the image sensor or the lens of the command signal to be output at a predetermined timing with respect to each filter with the arrival point of the image sensor or the lens of the operation command signal. The camera module according to claim 5, further comprising a misalignment compensation unit.   The said damping filter part has a parameter setting means which detects the resonant frequency of the said actuator, and determines the characteristic of the said damping filter based on the detected said resonant frequency. The camera module. An image sensor;
A lens having an optical axis substantially perpendicular to the light receiving surface of the image sensor;
An actuator for changing a relative position of the lens and the imaging device;
Command creating means for creating an operation command signal of the actuator;
Actuator driving means for driving the actuator based on the operation command signal,
The camera module according to claim 1, wherein the operation command signal is set such that a duration of a thrust applied to the actuator when the actuator moves is an integral multiple of a period of resonance vibration of the actuator.   The operation command signal input to the actuator driving unit by the command generating unit is an integer with respect to the period of all the resonance vibrations that the duration of the thrust suppresses when the actuator generates vibrations having a plurality of different frequencies. The camera module according to claim 8, wherein the signal is a doubled signal.   10. The camera module according to claim 8, further comprising parameter setting means for detecting a period of resonance vibration of the actuator and determining the duration based on the detected period of resonance vibration.

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