JP2006201593A - Imaging apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a compact imaging apparatus where the eccentricity and the tilt of a lens are reduced without providing a sliding part. <P>SOLUTION: By arranging 1st and 2nd magnetic bodies 9 and 11 so as to make repulsive force or attractive force act in a direction nearly orthogonal to the moving direction of a holding means 2, play of the holding means 2 and the fitting part 3 of a guide member is put aside without providing the sliding part indispensable in using an elastic member such as a leaf spring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus improved so as to improve stability during movement of an optical member and a control method thereof.

  2. Description of the Related Art Conventionally, in an imaging apparatus, there has been a problem that a subject image is blurred if a lens barrel having a lens movable in the optical axis direction is decentered or falls during movement for zooming or focusing. In particular, in a video camera or a digital camera, since an image during zooming or focusing can be recorded or observed on a monitor, it is desired that the subject image is not blurred.

  In a mechanism that supports a lens movably by a holding frame that holds the lens and a guide bar that fits the holding frame, so-called “backlash” is required for fitting the holding frame and the guide bar. In addition to taking into account changes due to temperature and humidity, the size of this play is designed to be slightly larger so that it does not disappear due to manufacturing errors. In other words, the play is necessary to some extent, and it is impossible to prevent the lens from decentering or falling by reducing the play. For this reason, conventionally, the lens is prevented from falling by increasing the fitting length between the holding frame and the guide bar. Furthermore, if the rattling of the lens cannot be suppressed even if the fitting length is increased, an elastic member such as a leaf spring is fixed to the holding frame and is slid on the inner surface of the lens barrel, and the rattling is performed. There was also a way to get rid of it.

  There is a method using a voice coil motor as means for driving the lens. This is because the wire is passed in a direction perpendicular to the magnetic flux from the magnetic field generator such as a permanent magnet, and the lens is driven using the force generated in the direction indicated by Fleming's left-hand rule according to the current flowing in the wire. Is. In a lens drive system using a voice coil motor, it is necessary to constantly monitor and feed back the lens position. In general, however, it consumes less power and is more responsive than a DC motor or step motor. There is a feature that it is low noise because of the lack of noise, and in recent years, it has been increasingly used in video camera lenses.

JP 2003-295249 A

  However, increasing the fitting length to reduce the tilting of the lens means that the guide bar extends in the optical axis direction, which is disadvantageous for downsizing the lens barrel. Further, since the eccentricity of the lens remains as much as the fitting play regardless of the fitting length, it is difficult to completely eliminate the blur of the subject image. In addition, when the elastic member is used, not only sliding resistance is generated, but also the elastic member is caught by flash or scratches on the inner surface of the lens barrel, which causes the holding frame to be loose. There was also.

  An object of the present invention is to solve the above-described problems, and to provide an image pickup apparatus that is small in size and has less eccentricity and tilting of a lens, and a control method therefor. In particular, an object of the present invention is to realize an imaging apparatus that stably moves with the addition of a minimum number of components and a control method thereof by utilizing components of a voice coil motor that has been increasingly used in lens drive systems in recent years. To do.

  An image pickup apparatus according to the present invention includes an optical member, a holding unit that movably holds the optical member, a driving unit that moves the holding unit together with the optical member, and a first magnetic body held by the holding unit. And a second magnetic body provided without being held by the holding means, separately from the holding means, and at least one of the first magnetic body and the second magnetic body Is a magnetic body that generates a magnetic field, and is configured to exert an attracting force or a repulsive force in a direction substantially perpendicular to the moving direction of the holding means.

  An image pickup apparatus control method according to the present invention includes an optical member, a holding means for holding the optical member movably, and a drive means for moving the holding means together with the optical member. The first magnetic body and the second magnetic body, at least one of which is a magnetic body that generates a magnetic field, are arranged so as to be held by the holding means, and the holding The second magnetic body is arranged separately from the means without being held by the holding means, and the first magnetic body and the second magnetic body are substantially perpendicular to the moving direction of the holding means. The holding means is biased so as to exert an attracting force or a repulsive force in the direction.

  According to the invention described in claims 1 and 5 of the present application, the first and second magnetic bodies are arranged so that the repulsive force or the attractive force acts in a direction substantially orthogonal to the moving direction of the holding means. The looseness of the fitting portion of the guide member of the holding means and the holding means can be offset without providing a sliding portion which is essential when an elastic member such as a leaf spring is used. It can be moved. In addition, this makes it possible to shorten the fitting length between the optical member and the guide member, so that further downsizing of the lens barrel can be realized.

  Further, according to the invention described in claim 2 of the present application, the driving means of the holding means is a voice coil motor, so that the permanent magnet constituting the voice coil motor is a magnetic body that generates a magnetic field that moves the holding means together. Since they can be used together, the holding means can be stably moved without a sliding portion by adding a minimum number of parts.

  Further, according to the invention described in claim 3 of the present application, the generation direction of the rotational force around the guide member due to the gravity of the holding means and the rotational force due to the magnetic material is made the same, so The holding means can be offset without the rotational force of the body canceling out.

  Further, according to the invention described in claim 4 of the present application, the generation direction of the rotational force around the guide member due to the gravity of the holding means and the rotational force due to the magnetic material is reversed, and the rotational force due to the magnetic material is applied to the optical member. By setting the holding means including the rotation force sufficiently larger than the rotational force due to the gravity, the holding means can be offset regardless of the use posture of the imaging apparatus.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing an example of an imaging apparatus according to the present invention.
Here, 101 is a lens that collects an image, 102 is a solid-state imaging device that photoelectrically converts the image into an analog signal that is image data, 103 is an analog signal processing circuit that processes the analog signal, and 104 is an analog signal that is converted into a digital signal. A / D converter for conversion, 105 a digital signal processing circuit for processing a digital signal, 106 a buffer memory for storing the digital signal, 107 a control circuit for controlling the operation of the entire apparatus, 108 for reading from the buffer memory 106 An interface for transferring the digital signal to the outside, 109 is a memory card that is detachable from the interface 108, 110 is a memory bus, and 111 is a holding frame for the lens 101. Here, the holding frame 111 is driven and controlled by the control circuit.

FIG. 2 is a schematic perspective view showing a lens support structure inside the lens barrel constituting the imaging apparatus of the present embodiment.
Here, 1 is a lens to be supported. In the present embodiment, the use of the lens 1 is not limited, and the lens 101 in FIG. 1 may be used for zooming or for focusing, as a matter of course. Furthermore, the present invention may be applied to a flat optical member such as an infrared ray cut filter or an optical low-pass filter instead of a lens.

  Reference numeral 2 denotes a holding frame that holds the lens 1. Reference numeral 3 denotes a fitting portion which is provided on the holding frame 2 and is fitted to a guide shaft 4 which will be described later. Reference numeral 4 denotes a guide shaft that is fitted to the fitting portion 3 and supports the holding frame 2 linearly and rotatably. The guide shaft 4 is fixed to a lens barrel body (not shown). Reference numeral 5 denotes a detent portion which is provided on the holding frame 2 and engages with a detent shaft 6 which will be described later. Reference numeral 6 denotes a non-rotating shaft that is fixed in parallel to the guide shaft 4 with respect to a lens barrel body (not shown) and fits to the anti-rotation portion 5 and serves to stop the rotation of the holding frame 2 around the guide shaft 4. . That is, the holding frame 2 is supported by the guide shaft 4 and the detent shaft 6 so as to be linearly movable.

  A large yoke 7 made of a ferromagnetic material such as iron has a rectangular shape without one of the four sides, and is fixed to the lens barrel body. Similarly, 8 is a small yoke, which has a shape that compensates for one side of the rectangle that the large yoke 7 lacks. Reference numeral 9 denotes a permanent magnet serving as a magnetic field generating unit, which is fixed inside the rectangular shape of the large yoke 7. Reference numeral 10 denotes a coil fixed to the holding frame 2 and having an electric wire wound in an annular shape, and is electrically connected to a controller (not shown) that controls the lens barrel outside the lens barrel body. The coil 10 penetrates one side of the large yoke 7 and is configured to move linearly together with the holding frame 2 in a space between the large yoke 7 and the permanent magnet 9.

  FIG. 3 is a front view of the perspective view of FIG. FIG. 3 shows the posture of the holding frame 2 in the main use posture of the imaging apparatus, and gravity works downward. In the drawings after FIG. 3, the same parts or parts are represented by the same numbers, and are not particularly described unless necessary. 4 is a cross-sectional view taken along the line II of FIG. As shown in FIG. 4, the permanent magnet 9 is magnetized in two poles, and the lines of magnetic force exist in the direction of the arrow p. The large yoke 7 and the small yoke 8 have an effect of suppressing leakage of the magnetic field lines to the outside, and the magnetic field lines of the permanent magnet 9 can be used efficiently.

  Since an electric current can flow through the coil 10 in a direction perpendicular to the magnetic field lines, an electromagnetic force is generated in the direction indicated by the Fleming's left-hand rule. Specifically, in FIG. 4, when a current flows from the front side to the back side in the portion intersecting the magnetic field lines of the coil 10, the number of turns of the coil, the magnitude of the current, The coil generates a force that is calculated by the product of the magnetic flux density and the length at which one electric wire intersects the magnetic field lines. If the direction of the current is reversed, the direction of force generation will also be reversed, and the magnitude of the generated force will change depending on the magnitude of the current, so it is maintained by controlling the magnitude and direction of the current flowing through the coil 10. The frame 2 can be moved along the guide shaft 4.

  Next, the fitting backlash will be described. Fitting play is absolutely necessary for sliding between parts. In the case of an imaging device, it is assumed to be used in various environments, taking into account the expansion and contraction and swelling of parts due to changes in temperature and humidity. Determine the amount of play. Furthermore, factors such as part manufacturing errors must be taken into account. Also in the present embodiment, the fitting portion 3 and the guide shaft 4, and the anti-rotation portion 5 and the anti-rotation shaft 6 each have fitting play. Since the holding frame 2 can move freely by the backlash, if no force is applied to the holding frame 2, the position and posture of the holding frame 2 are indefinite within the range of the fitting backlash.

  In FIG. 4, 11 is a one-sided magnet made of a permanent magnet fixed to the holding frame 2 and magnetized to two poles. The one-sided magnet 11 is magnetized so as to repel each other with the permanent magnet 9, and is always subjected to a downward repulsive force in FIG. 4 regardless of the movement of the holding frame 2. Furthermore, since the repulsive force is generated by a magnet, there is no sliding portion that is essential when an elastic member such as a leaf spring is used, and sliding friction and sliding due to flashing or scratching of the sliding surface do not occur in principle.

  Returning to FIG. 3, the force acting on the holding frame 2 will be described. In the main use posture of the image pickup apparatus, gravity is generated downward in FIG. 3, so that the holding frame 2 is rotated counterclockwise around the guide shaft 4. Furthermore, by applying a downward force by the one-sided magnet 11, a rotational force can be generated more strongly counterclockwise. When the magnet 11 is not provided, the holding frame 2 may be rattled due to vibration from outside the imaging apparatus or vibration when the holding frame 2 is driven. However, by providing the one-sided magnet 11 as in the present embodiment, the rotational force of the holding frame 2 can be strengthened and rattling can be suppressed. In addition, since rattling is suppressed, it is not necessary to suppress the maximum amount of rattling by increasing the mating length, and even if the mating length is shorter than before, stable lens movement without rattling is performed. be able to.

  Note that the magnetizing direction of the one-sided magnet 11 can be reversed, and the holding frame 2 can be one-sided by the attractive force. In this case, since the rotational force is generated in a direction opposite to the direction in which the rotational force is generated by gravity, in order to suppress the play of the holding frame 2, the attracting force by the one-sided magnet 11 is used as the lens 1 and the holding frame 2. It is necessary to make it sufficiently stronger than the total gravity acting on the coil 10. However, with this configuration, the holding frame 2 can be stably moved regardless of the usage posture of the imaging apparatus.

  In the present embodiment, a voice coil motor is used to drive the holding frame 2, but the present invention does not limit the driving method. However, the use of the voice coil motor can realize the offset without the sliding portion proposed by the present invention with the addition of the minimum parts.

(Second Embodiment)
FIG. 5 is a schematic front view showing the support structure of a certain lens inside the lens barrel constituting the imaging apparatus according to the present embodiment. The schematic configuration of the imaging apparatus according to the present embodiment is the same as that shown in FIG.

  In FIG. 5, reference numeral 21 denotes a supported lens. Reference numeral 22 denotes a lens holding frame that holds the lens 21. Reference numeral 23 denotes a fitting portion that is provided on the lens holding frame and is fitted to a guide shaft 24 described later. Reference numeral 24 denotes a guide shaft that is fitted to the fitting portion 23 and supports the holding frame 2 linearly and rotatably. The guide shaft 24 is fixed to a lens barrel body (not shown). Reference numeral 25 denotes a detent portion that is provided on the holding frame 22 and fits with a detent shaft 26 described later. Reference numeral 26 denotes a rotation-preventing shaft that is fixed to the lens barrel body (not shown) in parallel to the guide shaft 24 and fits to the rotation-preventing portion 25, and serves to stop the rotation of the holding frame 22 around the guide shaft 24. . That is, the holding frame 22 is supported by the guide shaft 24 and the detent shaft 26 so as to be linearly movable. FIG. 4 shows the posture of the holding frame 2 in the main use posture of the imaging apparatus, and gravity works downward.

6 is a cross-sectional view taken along the line JJ of FIG.
A yoke 27 made of a ferromagnetic material such as iron is fixed to the lens barrel body. Reference numeral 29 denotes a permanent magnet serving as a magnetic field generator, which is fixed inside the yoke 27. Reference numeral 30 denotes a coil fixed to the holding frame 22 and wound in an annular shape, and is electrically connected to a controller (not shown) that controls the lens barrel outside the lens barrel body. The coil 30 penetrates one side of the yoke 27 and is configured to move linearly together with the holding frame 22 in a space between the yoke 27 and the permanent magnet 29. The permanent magnet 29 is magnetized in two poles, and the lines of magnetic force exist in the direction of the arrow q. The yoke 27 has an effect of suppressing leakage of the magnetic field lines to the outside, and the magnetic field lines of the permanent magnet 29 can be used efficiently.

  Since an electric current can flow through the coil 30 in a direction perpendicular to the magnetic field lines, an electromagnetic force is generated in the direction indicated by the Fleming left-hand rule. If the direction of the current is reversed, the direction of force generation is also reversed, and the magnitude of the generated force changes according to the magnitude of the current. Therefore, the holding frame can be controlled by controlling the magnitude and direction of the current flowing through the coil 30. It is possible to move 22 along the guide shaft 24.

  In FIG. 6, 31 is a ferromagnetic iron piece fixed to the holding frame 22. Since the iron piece 31 receives the attracting force by the permanent magnet 29, it always receives the attracting force downward in FIG. 6 regardless of the position of the holding frame 22. Further, since this attractive force is generated by a magnet, there is no sliding portion that is essential when an elastic member such as a leaf spring is used, and sliding friction and sliding due to flashing and scratches do not occur in principle.

  Returning to FIG. 5, the force acting on the holding frame 22 will be described. Since gravity is generated downward in FIG. 5 in the main use posture of the imaging apparatus, the holding frame 22 generates a rotational force about the guide shaft 24 in the clockwise direction. Furthermore, the downward force by the iron piece 31 is added, and thereby a stronger rotational force can be generated in the clockwise direction. When the iron piece 11 is not present, the holding frame 22 may rattle due to vibration from outside the imaging apparatus or vibration when the holding frame 22 is driven. However, by providing the iron piece 11 as in the present embodiment, the rotational force of the holding frame 22 can be increased and rattling can be suppressed. In addition, since rattling is suppressed, it is not necessary to suppress the maximum amount of rattling by increasing the mating length, and even if the mating length is shorter than before, stable lens movement without rattling is performed. be able to.

  Instead of the iron piece 11, a permanent magnet may be arranged so as to be attracted to the permanent magnet 29. Further, even when the position of the image pickup device is reversed and the gravity direction in FIG. 4 is upward, the counterclockwise rotational force is generated in the holding frame 22 by gravity, but the attracting force of the permanent magnet is reduced to the lens 21. By making it sufficiently stronger than the sum of the gravitational forces acting on the holding frame 22 and the coil 30, the holding frame 22 can be moved stably regardless of the use posture of the imaging apparatus.

It is a block diagram which shows an example of the imaging device by this invention. It is a schematic perspective view which shows the support structure of the lens in the 1st Embodiment of this invention. It is a schematic front view which shows the support structure of the lens in the 1st Embodiment of this invention. It is a schematic sectional drawing which shows the support structure of the lens in the 1st Embodiment of this invention. It is a schematic front view which shows the support structure of the lens in the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the support structure of the lens in the 2nd Embodiment of this invention.

Explanation of symbols

1, 21 Lens 2, 22 Holding frame 3, 23 Fitting portion 4, 24 Guide shaft 5, 25 Anti-rotation portion 6, 26 Anti-rotation shaft 7 Large yoke 8 Small yoke 9, 29 Permanent magnet 10, 30 Coil 11 Magnet 27 Yoke 31 Iron piece

Claims (5)

An optical member;
Holding means for movably holding the optical member;
Drive means for moving the holding means together with the optical member;
A first magnetic body held by the holding means;
A second magnetic body provided separately from the holding means without being held by the holding means,
At least one of the first magnetic body and the second magnetic body is a magnetic body that generates a magnetic field, and exerts an attractive force or a repulsive force in a direction substantially perpendicular to the moving direction of the holding means. An image pickup apparatus configured as described above. The driving means includes
Magnetic field generating means that is the second magnetic body;
The imaging apparatus according to claim 1, further comprising: a coil disposed in the same magnetic field generated by the magnetic field generation unit. The driving means has a shaft that supports the holding means;
The first magnetic body and the second magnetic body are substantially orthogonal to the moving direction of the holding means and in the same direction as the direction of the rotational force around the axis due to gravity in the main use posture of the imaging device. The imaging apparatus according to claim 1, wherein the imaging apparatus is arranged to generate a rotational force by an adsorption force or a repulsive force. The driving means has a shaft that supports the holding means;
The first magnetic body and the second magnetic body are substantially orthogonal to the moving direction of the holding means and in a direction opposite to the direction of the rotational force around the axis due to gravity in the main use posture of the imaging device. The imaging apparatus according to claim 1, wherein the imaging apparatus is arranged to generate a rotational force stronger than a rotational force around the axis due to the gravity by an adsorption force or a repulsive force. An optical member;
Holding means for movably holding the optical member;
And a driving means for moving the holding means together with the optical member.
For the first magnetic body and the second magnetic body, at least one of which is a magnetic body that generates a magnetic field, the first magnetic body is disposed so as to be held by the holding means, and is separate from the holding means. Arranging the second magnetic body on the body without being held by the holding means,
The holding means is biased so that the first magnetic body and the second magnetic body exert an attracting force or a repulsive force in a direction substantially perpendicular to the moving direction of the holding means. Control method for imaging apparatus.

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