JP2011170260A - Imaging apparatus with shake correction function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which can compensate output fluctuation of a magnetic sensor caused by influence of temperature change in the apparatus, and can achieve accurate position detection under any temperature environment, and excels in accuracy of shake correction in terms of constitution of the conventional position detection circuit. <P>SOLUTION: The imaging apparatus with a shake correction function includes: a shake detection sensor; a shake amount calculation means; a shake correction means comprising driving magnets 11 and 12 and driving coils 13 and 14; a displacement detection means comprising position detection magnets 15 and 16 and position detection sensors 17 and 18; a control means suppressing a shake amount; and a holding mechanism 20 fixing an imaging device 19 and releasing the fixing. A position shifted by a fixed distance from a magnetic neutral point of the position detection magnets 15 and 16 is set as a fixing position where the imaging device 19 is fixed, and output from the position detection sensor obtained at the fixing position is acquired as a correction value, then the output from the position detection sensor obtained after starting shake correction is corrected by using the correction value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a blur correction function for correcting camera shake during shooting.

  In recent years, automation of imaging devices such as digital cameras has progressed, and those equipped with automatic exposure and automatic focus adjustment mechanisms have been widely put into practical use. A technology for realizing a shake correction function for correcting the image has been put into practical use.

  The position detection means of an imaging apparatus having a shake correction function is generally composed of a magnet that generates a magnetic force and a magnetic sensor that detects the magnetic force and produces an output proportional to the magnitude of the detected magnetic force. Yes.

  However, since these members have a large characteristic change due to temperature, a technique for mitigating the influence of environmental temperature is desired. On the other hand, a method has been proposed in which a temperature sensor is provided near the magnetic sensor to detect the temperature, and the magnetic sensor output is corrected according to the temperature level (see, for example, Patent Document 1).

  Patent Document 1 describes a technique for monitoring and correcting fluctuations in the ambient temperature of a magnetic sensor by detecting an input value to a Hall element, which is a magnetic sensor, as a position detection device capable of detecting temperature in real time. Has been.

  However, in order to monitor temperature fluctuations, it is necessary to provide a temperature sensor and a means for monitoring the Hall element input value in addition to the position detection means. This increases the number of parts and increases the signal wiring and increases the size of the apparatus. There is a problem of inviting up.

  Therefore, the present invention has been made in view of the above problems, and the influence of the temperature change in the apparatus is not included in the configuration of the conventional position detection circuit without adding a temperature sensor and further a magnetic sensor input value monitor circuit. It is an object of the present invention to provide an imaging apparatus that can compensate for fluctuations in the output of the magnetic sensor caused by the above-described sensor and can accurately detect the position under any temperature environment and has excellent blur correction accuracy.

In order to solve the above problems, an image forming apparatus according to the present invention is as follows.
[1] a blur detection sensor for detecting blur of the photographing apparatus;
A blur amount calculating means for calculating a position blur amount of the image on the image sensor surface from the blur amount of the device obtained from the output of the blur detection sensor;
Blur correction means composed of a drive magnet and a drive coil for moving the position of the image sensor;
A displacement detection means configured to detect a position derived from the magnetic force distribution of the magnet and the relative positional relationship of the sensor, comprising a position detection magnet and a position detection sensor for detecting the position of the image sensor;
Control means for controlling the position of the image sensor by the blur correction unit to suppress the blur amount based on the position blur amount of the image calculated by the blur amount calculation unit;
A holding mechanism that fixes the image sensor when the blur correction is not in operation and releases the fixation so that the image sensor can be moved during the blur correction operation;
The position where the image sensor is shifted by a certain distance in the moving direction from the magnetic neutral point of the position detection magnet is defined as a fixed position where the image sensor is fixed by the holding mechanism, and the output of the position detection sensor obtained at the fixed position is An image pickup apparatus with a shake correction function, which is obtained as a correction value and corrects the output of the position detection sensor obtained after the start of shake correction using the correction value.
[2] In the above [1], the drive current value applied to the position detection sensor when the correction value is acquired is controlled to be higher than a predetermined drive current value at the start of blur correction. It is an imaging device with a blurring correction function of description.
[3] The imaging apparatus with a blur correction function according to any one of [1] to [2], wherein the correction value is acquired only before the first image is captured during continuous shooting. is there.
[4] In the above [1] to [2], during the continuous shooting, the correction value is acquired at a predetermined interval before shooting the first image and when shooting the second and subsequent images. An imaging apparatus with a blur correction function according to any one of the above.

  According to the present invention, it is possible to compensate for fluctuations in the output of the magnetic sensor caused by the influence of the temperature change in the apparatus in the configuration of the conventional position detection circuit without adding a temperature sensor and further a magnetic sensor input value monitor circuit. In addition, it is possible to provide an imaging apparatus that is capable of accurate position detection under any temperature environment and excellent in shake correction accuracy.

As an effect of the present invention, according to the first aspect of the present invention, the position of the image on the image sensor surface is determined from the blur detection sensor for detecting the blur of the photographing apparatus and the blur amount of the apparatus obtained from the output of the blur detection sensor. A shake amount calculating means for calculating a shake amount, a shake correction means comprising a drive magnet and a drive coil for moving the position of the image sensor, a position detection magnet for detecting the position of the image sensor, and Based on a position detection sensor, a displacement detection means for detecting a displacement derived from the magnetic force distribution of the magnet and the relative positional relationship of the sensor, and the blur correction based on the position blur amount of the image calculated by the blur amount calculation means Control means for controlling the position of the image sensor by means to suppress the blur amount, and fixing the image sensor at the time of non-operation of blur correction, and the image sensor at the time of operation of blur correction A holding position that releases the fixation so that the image can be moved, and a position where the image pickup element is shifted from the magnetic neutral point of the position detection magnet by a certain distance in the moving direction is a fixed position where the image pickup element is fixed by the holding mechanism. The position detection sensor output obtained at the fixed position is obtained as a correction value, and the position detection sensor output obtained after the start of shake correction is corrected using the correction value. Therefore, there is no need to newly add a temperature sensor or temperature detection means near the magnetic sensor, and the correction value is taken in under any temperature condition immediately before the start of blur correction, and temperature correction is performed. Since an accurate position detection sensor output can be obtained, it is possible to avoid occurrence of a position detection error and perform highly accurate blur correction.
According to a second aspect of the present invention, in the imaging apparatus with a blur correction function according to the first aspect, the drive current value applied to the position detection sensor when the correction value is acquired is a predetermined drive current value at the start of blur correction. Since the control is performed to increase the gain of the position detection sensor and read the output, the accuracy of the acquired correction value is improved, and high-performance blur correction can be performed.
According to the invention of claim 3, in the imaging device with a blur correction function according to any one of claims 1 and 2, since the correction value is acquired only before shooting the first image during continuous shooting, The risk of missing a photo opportunity during the correction value acquisition can be avoided.
According to the invention of claim 4, in the imaging apparatus with a blur correction function according to any one of claims 1 and 2, a predetermined value is obtained before shooting the first image and when shooting the second and subsequent images during continuous shooting. Since the correction value is acquired at an interval of, it is possible to avoid the risk of missing a photo opportunity, and for example, the correction value can be acquired at a desired interval according to a predicted temperature fluctuation in the apparatus, Extremely high-precision blur correction can be performed. Moreover, failure of image shooting can be reduced.

It is an example of the blur correction means of the imaging device with a blur correction function of the present invention, (A) is an exploded perspective view, (B) is a partially enlarged view. It is explanatory drawing of a position detection sensor output, (A) is a temperature characteristic of a Hall element single-piece | unit, (B) is a temperature characteristic of a magnet, (C) is a graph which shows the temperature characteristic which synthesize | combined these. It is a block diagram of a shake correction control system of an imaging apparatus with a shake correction function of the present invention. It is a figure explaining the control in the imaging device with a blurring correction function of this invention, (A) is a schematic diagram which shows the movement range of FPC, (B) is a graph explaining the magnetic field distribution of a Y direction, (C) is a position. It is a graph which shows the difference in Hall element temperature characteristic by. It is a figure explaining the temperature fluctuation of the output of a Hall element by the fixed position (holding position) of an image sensor in the imaging device with a blurring correction function of the present invention. 4 is a flowchart illustrating control of an imaging apparatus with a blur correction function according to the present invention, in which (A) is a flow of a general zoom magnification apparatus, and (B) is a flow of a high zoom magnification apparatus. It is the schematic of the blur correction control circuit of the imaging device with a blur correction function of this invention. It is a graph which shows a gyro sensor output waveform. It is a graph which shows an angle conversion value. It is a graph which shows the target position of CCD at the time of performing blurring correction. It is a graph which shows the output of a Hall element as CCD position information.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments of the examples shown below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art. Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

1A and 1B show the shake correction means of the image pickup apparatus with a shake correction function of the present invention.
As shown in FIGS. 1A and 1B, a flexible printed circuit board (Flexible Printed Circuits, hereinafter referred to as “FPC”) 22 on which a CCD as an image sensor 19 is mounted is fixed to a Y movable frame 34, The movable frame 34 is supported so as to be movable in the Y direction along the Y guide shaft 32 fixed to the X movable frame 33. The Y movable frame 34 is supported so as to be movable in the X direction along the X guide shaft 31. The fixed frame 21 is fixed to the lens barrel body. As a result, the CCD 19 can move in both the X and Y directions.

Further, the FPC 22 is provided with an X drive coil 13 and a Y drive coil 14, provided at positions facing the X drive magnet 11 and the Y drive magnet 12, respectively, and driven in the X direction and the Y direction.
The positions in the X direction and the Y direction are detected by an X position detection sensor (X Hall element) 17 and a Y position detection sensor (Y Hall element) 18, respectively, and are controlled to predetermined positions by a control circuit.
As the X position detection sensor 17 and the Y position detection sensor 18, a magnetic sensor such as a Hall element or a magnetoresistive element is used, and is fixed to a Y movable frame 34 that moves in the X direction and the Y direction integrally with the FPC. The position of the FPC 22, that is, the position of the CCD 19 can be detected by detecting a change in the magnetic field by the position detection magnet 15 and the Y position detection magnet 16.

A digital camera, which is an image pickup apparatus equipped with a shake correction unit, is provided with a shake detection sensor 24, which detects a lateral (YAW) direction blur and a vertical (PITCH) direction blur of the camera. Based on the blur information obtained from the blur detection sensor 24, the movement of the CCD 19 is controlled so as to cancel the image blur on the CCD 19.
As the shake detection means, a gyro sensor which is an angular velocity sensor is generally used. The gyro sensor detects the angular velocity due to camera shake.

FIG. 3 is a block diagram of a shake correction control system in the imaging apparatus with a shake correction function of the present invention. As shown in FIG. 3, the offset of the output of the gyro sensor 41 from the reference voltage Vref is removed by a high pass filter (HPF) 42. This state is shown in the graph of the gyro sensor output waveform in FIG.
From the angular velocity signal from which the offset has been removed, high-frequency noise is removed by a low-pass filter (LPF) 43, A / D conversion is performed by an A / D converter 44, and taken into the control IC 25.

  The digitized angular velocity signal is integrated and converted into an angle signal, as shown in FIG. 9, multiplied by a coefficient k corresponding to the sensitivity of the gyro sensor 41 and the focal length of the imaging lens, and converted into a position signal. This position signal becomes the target position of the CCD 19 when blur correction is performed. This target position is shown in FIG.

  On the other hand, the signals detected by the Hall elements 17 and 18 as position sensors for detecting the position of the CCD 19 are subjected to A / D conversion by a low-pass filter (LPF) 43, and are taken into the control IC. This signal is the position of the CCD 19 shown in FIG.

  The difference between the target position of the CCD 19 shown in FIG. 11 and the actual position of the CCD 19 is multiplied by a predetermined gain, D / A converted by the D / A converter 45 as a control signal, and the drive coils 13 and 14 through the drive circuit 46. To supply power. In this way, feedback control is performed so that the CCD 19 follows the target position.

  When calculating the control signal, phase lead compensation is performed for the purpose of control stability.

In order to correct the shake amount calculated from the integrated value of the gyro output, the drive coils 13 and 14 are energized so as to shift the position of the CCD 19 in the opposite direction to the shake using the magnetic force of the drive magnets 11 and 12. The amount of CCD position deviation generated by energizing the coil is output from the relationship between the position detection magnets 15 and 16 and the Hall elements 17 and 18 which are position detection sensors.
Control is performed so that the position of the CCD 19 becomes the intended position by feeding back the output from the Hall element (hereinafter referred to as “Hall output”) and controlling the coil energization amount.

  However, since the heat is generated when the CCD 19 and the drive coils 13 and 14 are energized, the Hall elements 17 and 18 and the position detection magnets 15 and 16 arranged in the vicinity are output due to thermal fluctuations as shown in FIG. The characteristics will change.

For example, when the temperature rises by ΔT ° C., a temperature variation ΔVhole of the Hall element alone occurs, ΔVmag corresponding to the temperature variation of the position detecting magnet facing the Hall element is generated, and a variation as a combination of both ΔVh = ΔVhole + ΔVmag (1)
Will occur.

  FIG. 4A is a view as seen from the back of the lens unit 10 and shows an outline of the FPC 22 on which the CCD (imaging device) 19 is mounted and the movable frame area of the FPC 22 among the components constituting the blur correction mechanism. It is taken out. The movable direction of the CCD 19 is the vertical direction (Y direction) and the horizontal direction (X direction), and the moving range is limited by the fixed frame 21 in the vertical and horizontal directions of the movable end. At this time, it is assumed that the movable region is accurately managed according to the dimensions of the parts.

  Further, when the shake correction is not performed, the position of the FPC 22 is fixed (held) by the holding mechanism 20, and when the shake correction is performed, the position is canceled. The fixing (holding) / release operation is configured by a driving source such as a pulse motor or a DC motor, and a driving current is generated by a motor driver 27 that controls the motor.

  4B and 4C are diagrams illustrating an outline of blur correction control of the imaging apparatus with the blur correction function according to the present invention. Although only the Y direction has been described, the X direction is similarly applied.

As shown in FIG. 4B, the position where the FPC 22 is held by the holding mechanism 20 is defined as the origin 0, and the magnetic field zero which is the magnetic neutral point between the position detecting Hall element 18 and the position detecting magnet 16 at this time. The arrangement relationship with the position (Yzo) is shifted in the moving direction in advance.
Here, when the movable range of the CCD 19 is set to ± 1 mm, for example, the shift amount is set to 0.2 mm. This value is a level that can be sufficiently detected even when assembly variations are included.

  With this arrangement, as shown in FIG. 4C, the Hall element output at the magnetic neutral point (magnetic field zero position) becomes a stable output regardless of the environmental temperature, and the temperature is centered on this point. The output at the holding position (fixed position) is Vzo_n at normal temperature, Vzo_h at high temperature, and Vzo_l at low temperature. That is, as shown in FIG. 5, the hall output at the holding position varies depending on the temperature.

  At the position Yzo where the magnetic field is zero, the Hall output does not change even if the temperature fluctuates, and it remains stable with zero output. Therefore, using the characteristic that the gradient changes with this position as a reference, the hole at the holding position is used. The temperature fluctuation can be predicted only by observing the element output.

That is, the positional deviation amount between the position of the magnetic neutral point and the holding position is previously set to “Yzo”.
Further, the hall output “Vzo_n (at room temperature)” held in the holding position is acquired and stored before photographing.
The relationship between the actual hall output Vy obtained during blur correction and the position Y is
Y = Yzo + (Yzo / Vzo_n) × Vy (2)
Can be expressed as
On the other hand, when blur correction is performed in an arbitrary temperature environment, the hall output “Vzo” of the holding position is captured and stored as correction immediately before the start of blur correction, and the known holding position deviation amount Yzo and actually obtained at the time of blur correction. The following formula (3) is applied to the value of the hall output Vy for conversion, and the hall output fluctuation due to temperature is corrected.
Y = Yzo + (Yzo / Vzo) × Vy (3)

Fig. 5 shows the temperature fluctuation of the Hall output at the holding position. If the Hall output value at the holding position deviated from the position of the magnetic neutral point is taken as the correction value, correction at any temperature is possible. It becomes.
After the photographing is completed, the holding mechanism 20 is locked and the FPC 22 is fixed, and it waits for the next photographing.

FIG. 6A shows an example of a flowchart showing the control of the imaging apparatus with a blur correction function of the present invention.
As shown in FIG. 6A, when release 1 is pressed (S101), the hall output Vzo at the holding position is acquired (S102). Next, when the holding mechanism is released (released) (S103) and release 2 is pressed (S104), the acquired Vzo is set as a correction value (S105), and camera shake correction is controlled (S106). After the photographing is finished, the holding mechanism is locked (S107), and the FPC is fixed again and finished.

  When an image pickup apparatus with a blur correction function has a wide movable range, such as a digital camera with a high zoom magnification, for example, it is necessary to have a dynamic range to the movable end when setting the hall element drive current at the time of blur correction. The current of can not flow. When a sufficient S / N ratio cannot be obtained, the drive current value applied to the position detection sensor (Hall element) when acquiring the correction value is set higher than the predetermined drive current value at the start of blur correction. Only at the time of control, that is, when a correction value is acquired, the sensitivity may be improved by increasing the drive current of the Hall element.

Control of the drive current flowing through the Hall element is performed in the Hall element drive circuit shown in FIG.
Assuming that the driving current at the time of blur correction is I, the driving current at the time of obtaining the correction value is I0, and the Hall output value at the holding position is V0, the Hall output is proportional to the driving current. ) And at the time of blur correction, the current value is returned to I.
Vzo = V0 / I0 × I (4)

FIG. 6B shows an example of a flowchart showing the control of the imaging apparatus with a blur correction function in this case.
As shown in FIG. 6B, when release 1 is pressed (S201), the hall element drive current is increased by a predetermined amount to I0 (S202), and the Hall output correction value Vzo is obtained (S203). After obtaining the correction value, the Hall element drive current is returned to the predetermined value I (S204), and then the holding mechanism is released (released) (S205). Next, when release 2 is pressed (S206), the correction value represented by the above equation (4) is set (S207), and camera shake correction is controlled (S208). After the photographing is finished, the holding mechanism is locked (S209), and the FPC is fixed again and finished.

In the case of shooting only one image in shooting using an imaging device, it is considered that there is no problem by taking a correction value immediately before shooting as described above.
On the other hand, in the case of continuous shooting, the holding / releasing operation by the holding mechanism is repeated in order to capture the correction value before each shooting, and as a result, the shooting interval may become long, and there is a risk of missing a photo opportunity. Therefore, the correction value may be captured only immediately before the first image is captured.

  Also, if the temperature fluctuation in the camera is known in advance, the holding mechanism is held / released at the desired shooting interval to obtain the correction value before the correction accuracy is extremely deteriorated due to the influence of the temperature fluctuation. May be.

  The image pickup apparatus with shake correction function of the present invention according to the above-described embodiment has the effect of temperature change in the apparatus in the configuration of the conventional position detection circuit without adding a temperature sensor and further a magnetic sensor input value monitor circuit. Can compensate for fluctuations in the output of the magnetic sensor, enable accurate position detection under any temperature environment, perform highly accurate blur correction, and reduce image shooting failures.

DESCRIPTION OF SYMBOLS 10 Lens unit 11 X drive magnet 12 Y drive magnet 13 X drive coil 14 Y drive coil 15 X position detection magnet 16 Y position detection magnet 17 X position detection sensor 18 Y position detection sensor 19 Imaging element (CCD)
20 Holding Mechanism 21 Fixed Frame 22 FPC (Flexible Printed Circuit Board)
23 Control Board 24 Shake Detection Sensor 25 Control LSI
26 Temperature sensor 27 Driver 28 Holding hole 31 X guide shaft 32 Y guide shaft 33 X movable frame 34 Y movable frame

JP 2006-47054 A

Claims (4)

A blur detection sensor for detecting blur of the photographing device;
A blur amount calculating means for calculating a position blur amount of the image on the image sensor surface from the blur amount of the device obtained from the output of the blur detection sensor;
Blur correction means composed of a drive magnet and a drive coil for moving the position of the image sensor;
A displacement detection means configured to detect a position derived from the magnetic force distribution of the magnet and the relative positional relationship of the sensor, comprising a position detection magnet and a position detection sensor for detecting the position of the image sensor;
Control means for controlling the position of the image sensor by the blur correction unit to suppress the blur amount based on the position blur amount of the image calculated by the blur amount calculation unit;
A holding mechanism that fixes the image sensor when the blur correction is not in operation and releases the fixation so that the image sensor can be moved during the blur correction operation;
The position where the image sensor is shifted by a certain distance in the moving direction from the magnetic neutral point of the position detection magnet is defined as a fixed position where the image sensor is fixed by the holding mechanism, and the output of the position detection sensor obtained at the fixed position is An image pickup apparatus with a blur correction function which is obtained as a correction value and corrects the output of the position detection sensor obtained after the start of blur correction using the correction value.   The blur correction according to claim 1, wherein the drive current value applied to the position detection sensor when the correction value is acquired is controlled to be higher than a predetermined drive current value at the start of blur correction. Imaging device with function.   The imaging apparatus with a blur correction function according to claim 1 or 2, wherein the correction value is acquired only before the first image is shot during continuous shooting.   3. The blur correction function according to claim 1, wherein the correction value is acquired at a predetermined interval before shooting the first image and when shooting the second and subsequent images during continuous shooting. An image pickup device.

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