JP2010237250A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an imaging apparatus that obtains high optical performance in various states in which an imaging optical system is used, by satisfactorily adjusting each lens group under various conditions of the imaging optical system. <P>SOLUTION: The imaging apparatus includes: the imaging optical system having a movable lens group and an eccentric lens group which can be eccentrically driven with respect to an optical axis; a drive control means for controlling the detection of the position of the movable lens group and its drive; and a control means for controlling the drive of the movable lens group and eccentric lens group. In the imaging apparatus, the control means corrects image quality by eccentrically driving the eccentric lens group relative to the optical axis on the basis of positional information of the movable lens group obtained by the drive control means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and is suitable for an imaging apparatus such as a video camera, a digital camera, and a TV camera having an optical correction unit that corrects image quality.

  In recent years, an image pickup element used in an image pickup apparatus such as a video camera or a digital camera has been increased in the number of pixels, and accordingly, an image quality of an obtained image has been improved. In addition, an imaging optical system used therefor is required to have high performance corresponding to high image quality and a small assembly error of each lens group. In order to obtain an image pickup apparatus with little assembling error of each lens group, it is not always sufficient to improve the member accuracy of each lens group constituting them. For this reason, there is known a lens barrel having an optical member assembling adjustment means that adjusts an error of each lens group after assembling so as to prevent image deterioration due to variations in each lens group and between lens groups. (Patent Document 1).

JP-A-9-329737

  In general, in the adjustment of the optical member (lens group), each optical member is fixed and held on the lens barrel using a UV adhesive after the adjustment. In the adjustment at this time, the adjustment is performed under a fixed condition of the optical system, for example, a fixed focal length, a focus position, and an aperture value. Therefore, a good image can be obtained under these conditions. However, when the imaging optical system is a zoom lens, the degree of influence on each aberration with respect to decentering, which is one of the assembly errors of each lens group, varies under setting conditions such as a zoom position, a focus position, and an aperture value. For this reason, even if the adjustment is appropriate under one condition, the aberration canceling conditions and ratios of the lens groups differ under other conditions, which are not necessarily sufficient under other conditions.

  In the zoom lens, adjustment is performed by canceling out aberrations with the lens unit that affects the resolving power at the wide angle (wide-angle end) due to parallel decentering of the afocal fixed lens unit. Then, it is assumed that the adjustment is performed using the cancellation of aberration with the lens group that affects the image plane (one-sided blur) at the telephoto (telephoto end). In this case, there may be a difference in the best eccentric position of the adjustment lens group between the wide and tele zoom positions. For this reason, it is difficult to obtain a high-quality image under conditions other than the fixed adjustment, for example, over the entire zoom range.

  In addition, when the optical system is a multi-stage collapsible lens barrel, the decentering state of each lens group also changes depending on the posture of the lens unit such as upward, downward, vertical position, and horizontal position. For this reason, it is difficult to obtain high image quality at each posture position. In addition to the above, in the case of an image-capturing apparatus in which a lens can be exchanged, the mounting position for each camera, the focus position due to a flange back position error, and the like differ. For this reason, it becomes difficult to obtain a high-quality image only by adjusting the interchangeable lens alone.

  An object of the present invention is to provide an imaging apparatus in which each lens group is well adjusted under various conditions of the imaging optical system, and high optical performance is obtained in various usage states of the imaging optical system.

  An imaging apparatus according to the present invention includes an imaging optical system having a movable lens group and an eccentric lens group that can be driven eccentrically with respect to the optical axis, drive control means for controlling detection and driving of the position of the movable lens group, In the imaging apparatus having the movable lens group and a control unit that drives and controls the decentered lens group, the control unit determines the position of the decentered lens group from the position information of the movable lens group obtained by the drive control unit as an optical axis. The image quality is corrected by driving eccentrically.

  In addition, the imaging apparatus of the present invention is an imaging apparatus including an imaging optical system, and the imaging apparatus is biased with respect to an optical axis of the imaging optical system and attitude detection means for detecting the attitude state of the imaging apparatus. A decentered lens group that can be driven by a core, a storage means that stores in advance the amount of decentering of the decentered lens group based on the amount of the posture state, And a control unit that drives and controls the decentered lens group using the stored data.

  In addition, the imaging apparatus of the present invention includes a camera main body and factor data relating to image quality performance of the camera body, and factors relating to image quality performance of the interchangeable lens in an imaging apparatus having an interchangeable lens detachable from the camera main body. It is characterized by having a control means for adjusting the position of the decentered lens group constituting a part of the imaging optical system of the interchangeable lens using data.

  According to the present invention, it is possible to obtain an image pickup apparatus in which each lens group is well adjusted under various conditions of the image pickup optical system, and high optical performance can be obtained in various use states of the image pickup optical system.

1 is a block diagram of an image pickup apparatus showing the movement of each lens group in Embodiment 1 of the present invention. Explanatory drawing showing the influence degree to the aberration of each lens group in each embodiment of the present invention Block diagram of each lens group state and imaging device in Embodiment 2 of the present invention Block diagram of each lens group state and imaging apparatus in Embodiment 3 of the present invention

  For reference, the imaging device of the present invention is described below with reference numerals of members to be described later. An imaging optical system that constitutes a part of the imaging apparatus of the present invention includes a movable lens group 12 and an eccentric lens group 13 that can be driven eccentrically with respect to the optical axis 02. The control means 16 for driving and controlling the movable lens group 12 and the eccentric lens group 13 causes the eccentric lens group 13 to be eccentrically driven with respect to the optical axis 02 from the position information of the movable lens group 12 obtained by the drive control means 15. The image quality has been corrected. For example, image quality degradation is improved.

[Example 1]
FIG. 1 is a block diagram showing the movement of each lens group of the zoom lens (imaging optical system) according to Example 1 of the present invention. 1A shows the zoom position 1, and FIG. 1B shows the zoom position 2. For example, the zoom position 1 indicates wide (wide angle end), and the zoom position 2 indicates a tele state (telephoto end).

  Reference numeral 01 denotes an image sensor on which image information is formed. 02 indicates the optical axis of the zoom lens. Here, the optical axis is generally a central line concept of an optical system, and is a line passing through the centers of curvature of a plurality of lens surfaces. In an actual optical system, there is an individual eccentricity of the lens, so this is an imaginary concept. For example, it may be an imaging center line that does not cause a shift of the zoom center during zooming (depends on the eccentricity of the variator). Further, it may be the principal ray of the F-number light beam from the screen center of the image sensor (depending on the eccentricity of the stop). In addition, the center lines of the light beams incident on the four peripheral portions on the image sensor are balanced (depending on the eccentricity of the cut portions of the upper and lower light beams). Here, for convenience of explanation, it is assumed that the optical axis is an image plane center line that is a straight line perpendicular to the screen center of the image sensor 01.

  The lens barrel 101 is detachably attached to the camera body 102 (replaceable). Reference numeral 11 denotes a first front lens group (first group) which is attached to the lens barrel 101 without eccentricity. Reference numeral 12 denotes a two-group variator lens group (two groups, a movable lens group). In the drawing, as an example, the two-group variator lens group is attached with the eccentricity parallel to the upper direction. Reference numeral 15 denotes drive control means for performing drive control in the optical axis direction and position detection in the optical axis direction of the second group 12. Reference numeral 13 denotes a three-group afocal lens group (three groups, an eccentric lens group). Reference numeral 18 denotes drive control means for performing drive control and position detection of the third group 13. The third group 13 is controlled by the drive control means 18 so as to be finely movable in order to correct aberrations in the parallel eccentric direction. This is realized by a mechanical actuator mechanism such as a shift image stabilizing mechanism in order to reduce image blur and image quality degradation.

  Reference numeral 14 denotes a fourth group, which performs a focusing action. The 4th group 14 has shown the case where it decenters in the downward direction as an example in drawing. Reference numeral 17 denotes drive control means for performing drive control and position detection of the fourth group 14. Reference numeral 16 denotes a control circuit section (control means) for driving and controlling the lens groups 12, 13, and 14, and includes storage means for correction positions of the third group 13 based on position information of the second group 12 or the fourth group 14. Reference numeral 20 denotes an image processing means, which determines the cut-out position of image information obtained from the image sensor 01 corresponding to the change in the center position of the screen that occurs when the movable lens group 12 moves or the center position of the light beam incident on the periphery of the screen. It is changing.

  At the zoom position 1 (wide-angle end) in FIG. 1A, the influence of aberration generated by the rear focus lens group (fourth group) 14 is large. For example, the influence on the resolution at the center of the screen is large. Therefore, the drive control means 17 detects the parallel eccentricity (downward in the figure) of the fourth group 14. Then, from the position detection information of the fourth group 17 by the drive control means 17, the control circuit 16 follows the correction information stored in the storage means relating to the third group 13 in advance, and the third group 13 is parallel to the lower direction in the same manner as the fourth group 14. The drive control means 18 is controlled so as to perform eccentric drive control. As a result, the aberration caused by the parallel decentering of the fourth group 14 is canceled.

  At the zoom position 2 (telephoto end) in FIG. 1B, the influence of aberration generated by the variator lens group (second group) 14 is large. For example, the influence on the fall of the image plane is great. Therefore, the drive control means 15 detects the parallel eccentricity (upward direction in the figure) of the second group 12. Then, from the position detection information of the second group 12 by the drive control means 15, the control circuit 16 follows the correction information stored in advance in the storage means related to the third group 13, and the third group 13 is moved upward as in the second group 12. The drive control means 18 is controlled so as to perform parallel eccentric drive control. Thereby, the aberration generated by the parallel decentering of the second group 12 is canceled.

  Next, the influence degree with respect to the aberration of each lens group regarding the parallel eccentricity of each lens group of the present embodiment will be described. 2A and 2B are graphs showing the degree of influence of each lens group on the aberration. 2A corresponds to the zoom position of FIG. 1A, FIG. 2B corresponds to the zoom position 2 of FIG. 1B, and each lens group is decentered in the same direction. The degree of influence on the aberration is shown. This graph is shown as an example, and differs depending on the type of the imaging optical system. The upward and downward directions of the graph indicate that aberrations are canceled out each other, and the height of the graph indicates the value of the degree of influence on the aberration.

  In FIG. 2, 21 a and 21 b represent the first group 11, 22 a and 22 b represent the second group 12, 23 a and 23 b represent the third group 13, 24 a and 24 b represent the aberration influence degree of the fourth group 14, respectively. The amount of vertical movement in the graph indicates the value of the degree of influence on the aberration when the specified amount of the lens group is decentered. The vertical direction indicates the direction in which the aberration occurs. This shows that the aberration can be canceled by the amount.

  2A, from the decentering amount of the fourth group 14 and its aberration influence level 24a, the third group 13 is adjusted in the same direction as the fourth group 14 and the value of the aberration influence level 23a in order to correct the aberration generation amount. The aberration amount can be canceled and corrected by calculating the decentering amount of the third group 13. Similarly, from the graph of FIG. 2B, at the zoom position 2, the aberration influence degree 22b of the second group 12 has a large influence, and a large aberration is generated.

From FIG. 1B, the second group 12 and the fourth group 14 are eccentric with respect to the optical axis 02 in the opposite direction. Thus, it can be seen that the degree of influence 24b of the eccentricity of the fourth group 14 on the aberration and the degree of aberration influence 24b of the eccentricity of the second group 12 on the aberration work in a direction to cancel each other. Therefore, the third group 13 shown in FIG. 1B is decentered so as to correct the remaining aberrations of the aberrations canceled out by the second group 12 and the fourth group 14. In this embodiment, the third group 13 is controlled to be eccentrically driven in the same direction as the second group 12 and less than the eccentric amount of the second group 12. According to this, aberration can be canceled.
Here, although the aberration influence of the first group is large, since the first front lens group (first group) is attached to the lens barrel 101 without decentering as described above, no aberration occurs.

  The actual drive control amount of the third group 13 is optically measured at a plurality of zoom positions using a collimator or a camera image. Then, the third group 13 is driven to check the image, and the driving position of the third group 13 at the time when it enters a problem-free range (standard value or the like) is stored in the storage means in the control circuit 16 together with the zoom position. In actual use, the drive positions of the third group 13 with respect to the zoom position from the drive control means 15 are called from the storage means in the control circuit 16. By performing interpolation processing and driving control between a plurality of zoom positions, it is possible to obtain high image quality with aberrations corrected over a wide zoom range.

  Although an example has been described above, the same applies to the case where the aberration varies depending on the focus position. For example, even when the amount of aberration changes depending on the aperture value, aberration correction can be performed by performing correction control in advance in the storage unit in the control circuit (control unit) 16 based on information on each condition. In addition, the actual amount of eccentricity correction is an HD imaging lens using a 1/3 inch imaging device. The correction amount is usually a small amount of about 50 μm or less driven with an accuracy of several μm. However, the present embodiment is not limited to this.

[Example 2]
A second embodiment of the present invention will be described. The second embodiment is an embodiment in which the image pickup optical system (image pickup lens) is decentered depending on the use posture of the camera and the image quality is prevented from being deteriorated when the image quality is affected. FIG. 3 is a principal block diagram of an optical apparatus (imaging apparatus) using a retractable photographing lens. FIG. 3 shows a state in which a part of the lens group of the photographing lens is tilted downward and forward at the time of photographing due to gravity. In a retractable photographic lens, in many cases, a lens barrel portion of a lens group is fitted into three grooves of a cam ring by three cam pins.

  Each lens group may be driven by the rotation of the cam ring, and there may be a play of several tens of microns between the groove of the cam ring and the cam pin for manufacturing reasons. Therefore, when the retractable structure is adopted for downsizing the photographing lens, a cam pin is disposed at the rear end (image side end) of the movable lens barrel. For this reason, even in a horizontal state, the movable lens barrel may be tilted forward and downward due to the influence of gravity. Therefore, even if the aberration correction lens is adjusted in the horizontal position and then bonded and fixed, the movable lens barrel tilts in a different direction by 90 degrees when shooting at the vertical position. It may not be said.

  In FIG. 3, reference numeral 31 denotes a first group barrel which holds a first group lens group (first group, movable lens group) 31a. 31b indicates the optical axis of the first group 31a. Reference numeral 32 denotes a second group barrel, which holds a second group lens group (two groups, an eccentric lens group) 32a. Reference numeral 32b denotes the optical axis of the second group 32a. The second group lens group 32a is movable in a surface direction perpendicular to the optical axis 32b of the second group 32a. A drive control unit 32d performs driving and position detection, and corrects the aberration by driving and controlling the position of the second group 32a so as to correct the aberration caused by the change in the posture of the camera. Reference numeral 33 denotes a camera body fixing unit, which includes a focus lens group (third group) 33 a and an image sensor unit 34. The position of the focus lens group 33a is detected and controlled by the drive control means 33c. A zoom drive motor 36 rotates the cam ring. Reference numeral 37 denotes a zoom position detector that detects the position of the second group 32a on the optical axis. Reference numeral 35 denotes a control circuit (control means) that controls the entire lens system, and drives and controls the second group 32a for correction using a plurality of information including information from the posture detection means 38.

  Here, the plurality of information includes, for example, information from the zoom position detection unit 37, focus position information from the drive control unit 33c, and aperture information from the aperture value detection unit 32d. In addition, the correction amount calculated from the correction reference value stored in advance in the storage means in the control circuit 35 is the drive correction amount for the aberration correcting eccentric lens 32a. Based on these pieces of information, correction drive control of the eccentric lens 32a for aberration correction is performed. The postures that can be detected by the posture detection means 38 are not only the upward and downward of the lens barrel, but also the detection of the vertical position and lateral position of the camera or the posture / tilt in each direction. For the eccentricity adjustment, at least one of a correction method using parallel eccentricity and inclination eccentricity can be applied. The correction of image quality performance is to correct one or more aberrations or wavefront aberrations among the aberrations belonging to Seidel's five aberrations.

  The same applies to other embodiments. The correction reference value in which the drive correction amount of the decentering lens 32a for aberration correction is stored in advance is a numerical value obtained by measurement or design at the time of shipment from the factory. Multiple conditions are stored for each state, and the conditions between them are obtained by interpolation processing. In the present embodiment, the control unit 35 drives and controls the decentered lens group using data stored in the storage unit in advance based on the amount of the posture state obtained by the posture detection unit that detects the posture state of the imaging apparatus. ing. This reduces image quality degradation when using a retractable lens barrel.

[Example 3]
A third embodiment of the present invention will be described. In this embodiment, aberration variations caused by both of them are corrected when an interchangeable lens is detachably attached to the camera body. FIG. 4 is a principal block diagram of the interchangeable lens system according to the third embodiment. Reference numeral 41 denotes an interchangeable lens unit that has an aberration correction eccentric lens group 41a inside. Reference numeral 42 denotes storage means for storing a state relating to the performance of the interchangeable lens unit 41. Reference numeral 45 denotes a camera body having an image sensor section 43. The camera main body 45 is provided with storage means 46 for storing information relating to the imaging performance of the imaging unit of the camera.

  When the interchangeable lens unit 41 is attached to the camera body 45 in the above-described form, communication is performed through the contact of the mount, and information from the storage unit 42 is input to the control system block (control unit) 47 of the camera body unit 45. Is done. Similarly, information on the camera body 45 side is input to the control system block 47 from the storage means 46 of the camera body 45. The control system block 47 returns communication to the interchangeable lens unit 41 side based on information on both the interchangeable lens unit 41 side and the camera body 45 side, and inputs a drive command relating to the movement of the decentered lens group 41a to the drive control unit 48. To do. The drive control means 48 performs parallel eccentric drive of the lens group 41a based on the signal at this time, and corrects aberrations that occur when the interchangeable lens is replaced.

  As described above, in this embodiment, the control system block (control means) 47 uses a factor data related to the image quality performance of the camera main body 46 and a factor data related to the image quality performance of the interchangeable lens 41 to configure a part of the imaging optical system in the interchangeable lens. The position of the decentering lens group 41a to be configured is adjusted. As a result, image quality deterioration due to both factor data when various interchangeable lenses are attached to the camera body 45 is reduced. Moreover, in the embodiment of the present proposal, an example in which the image sensor is fixed has been shown. However, even when the imaging element is movable in the optical axis direction like other movable lens groups, it corresponds to the eccentric amount for each position. This can be applied by performing decentration correction by the decentering lens group.

11: 1 group, 12: 2 group, 13: 3 group, 14: 4 group, 16: control circuit (control means), 15 · 17 · 18 · 48 · 32d · 33c: drive control means, 31: 1 group mirror Cylinder, 32: 2 group lens barrel, 33/102: camera body, 34: imaging device unit, 35/47: control circuit (control means), 36: zoom drive unit, 37: zoom position information detection unit, 38: posture Detection means, 101: lens barrel

Claims (5)

An imaging optical system having a movable lens group and an eccentric lens group that can be driven eccentrically with respect to the optical axis, drive control means for controlling detection and driving of the position of the movable lens group, the movable lens group and the polarization And an image pickup apparatus having a control unit that drives and controls the core lens group. The control unit causes the eccentric lens group to be decentered with respect to the optical axis based on position information of the movable lens group obtained by the drive control unit. An image pickup apparatus for correcting image quality. The image pickup apparatus includes an image pickup element on which image information is formed, and the image pickup element corresponding to a change in a screen center position or a center position of a light beam incident on a peripheral portion of the screen that occurs when the movable lens group moves. 2. The image pickup apparatus according to claim 1, further comprising image processing means for changing a cutout position of image information obtained from the image data. An image pickup apparatus including an image pickup optical system, the image pickup apparatus detecting an attitude state of the image pickup apparatus, an eccentric lens group that can be eccentrically driven with respect to the optical axis of the image pickup optical system, Using the storage means that stores in advance the amount by which the decentering lens group is eccentric based on the amount of the posture state, and the data stored in the storage means based on the signal from the posture detection means, the eccentricity An image pickup apparatus comprising: a control unit that drives and controls the lens group. In an imaging apparatus having a camera body and an interchangeable lens that can be attached to and detached from the camera body, the imaging data of the interchangeable lens using factor data relating to image quality performance of the camera body and factor data relating to image quality performance of the interchangeable lens An image pickup apparatus comprising: control means for adjusting a position of an eccentric lens group constituting a part of the system. The control means decenters the decentered lens group to correct one or more aberrations among Seidel's five aberrations of the imaging optical system, or corrects wavefront aberration. Item 5. The imaging device according to any one of Items 1 to 4.