WO2007145194A1 - Système optique de formation d'image, dispositif de lentille de formation d'image et appareil numérique - Google Patents

Système optique de formation d'image, dispositif de lentille de formation d'image et appareil numérique Download PDF

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Publication number
WO2007145194A1
WO2007145194A1 PCT/JP2007/061783 JP2007061783W WO2007145194A1 WO 2007145194 A1 WO2007145194 A1 WO 2007145194A1 JP 2007061783 W JP2007061783 W JP 2007061783W WO 2007145194 A1 WO2007145194 A1 WO 2007145194A1
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WIPO (PCT)
Prior art keywords
lens
lens group
optical system
positive
imaging
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PCT/JP2007/061783
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English (en)
Japanese (ja)
Inventor
Keiko Yamada
Kenji Konno
Original Assignee
Konica Minolta Opto, Inc.
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Publication date
Application filed by Konica Minolta Opto, Inc. filed Critical Konica Minolta Opto, Inc.
Priority to JP2008521203A priority Critical patent/JP5062173B2/ja
Publication of WO2007145194A1 publication Critical patent/WO2007145194A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/145—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only
    • G02B15/1451—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive
    • G02B15/145129—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive arranged +-+++
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/04—Prisms

Definitions

  • Imaging optical system imaging lens device, and digital device
  • the present invention relates to an imaging optical system that constitutes a zoom lens system, an imaging lens device including the imaging optical system, and a digital device equipped with the imaging lens device.
  • Patent Documents 1 to 3 disclose an imaging optical system of a zoom lens system.
  • Patent Document 1 a four-group zoom configuration in which lenses having optical power of “positive / negative / positive / positive” are arranged in order from the object side, and a lens group having optical power of “positive / negative / positive / positive” are arranged.
  • a zoom lens system is disclosed in which a first lens group includes a prism for bending the optical axis at a right angle.
  • Patent Document 2 also discloses a “positive / negative / positive / positive” 5-group zoom configuration in which the first lens group includes a bending prism.
  • Patent Document 3 discloses that the first lens group has a bending pre-refractive index of 1.9 or more.
  • a zoom lens system is disclosed that has a positive, negative, positive, positive five-group zoom configuration that moves the second, fourth, and fifth lens groups during zooming! RU
  • Patent Documents 1 to 3 specifically describe sufficient measures for suppressing an increase in aberration fluctuation that occurs when the entire length of the zoom lens system is reduced. Absent. That is, in the “positive / negative / positive / positive” 5-group zoom lens system disclosed in Patent Documents 1 to 3, the zooming load during zooming of each lens group is optimized. When the overall length of the zoom lens system is shortened, the aberration fluctuation during zooming increases as the power of each lens group increases. For this reason, good performance cannot be obtained over the entire zoom range, and its compactness is limited.
  • Patent Document 1 Japanese Patent Laid-Open No. 2003-202500
  • Patent Document 2 JP-A-2004-347712
  • Patent Document 3 Japanese Patent Laid-Open No. 2005-338143
  • An object of the present invention has been made in view of the above circumstances, and provides an imaging optical system, an imaging lens device, and a digital device equipped with the imaging lens device that are compact and have high optical performance. There is.
  • An imaging optical system includes a plurality of lens groups, and changes the interval between the lens groups.
  • An imaging optical system capable of zooming in order, having a positive optical power in order from the object side, fixed at the time of zooming, and a reflecting member that bends the optical axis at a substantially right angle
  • a first lens group that includes negative optical power
  • a second lens group that is movable in the optical axis direction
  • a third lens group that has positive optical power
  • a positive optical power and a positive optical power.
  • a fourth lens group movable in the optical axis direction and a fifth lens group having positive optical power and movable in the optical axis direction.
  • dl2w Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the wide-angle end
  • dl2t Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the telephoto end
  • An imaging lens device includes the imaging optical system described above and imaging that converts an optical image into an electrical signal. And the imaging optical system is assembled on the light receiving surface of the imaging element so as to form an optical image of a subject.
  • a digital device includes the above-described imaging lens device, and a control unit that causes the imaging lens device to perform at least one of photographing a still image and a moving image. It is characterized by comprising.
  • FIG. 1 is a diagram schematically showing a configuration of an imaging optical system according to an embodiment of the present invention.
  • FIG. 2 shows an external configuration of a digital camera showing an embodiment of a digital device according to the present invention.
  • FIG. 2A is a front view of a digital camera
  • FIG. 2B is a rear view
  • FIG. 2C is a top view.
  • FIG. 3 is a functional block diagram schematically showing an electrical functional configuration of a digital camera.
  • FIG. 4 is a cross-sectional view of the configuration of the imaging optical system of Example 1 with the optical axis cut longitudinally.
  • FIG. 5 is a linear optical path diagram showing the configuration of the imaging optical system of Example 1 with the prism portion developed in a straight line.
  • FIG. 6 is a straight optical path diagram showing the configuration of the imaging optical system of Example 2 with the prism portion developed in a straight line.
  • FIG. 7 is a linear optical path diagram showing the configuration of the imaging optical system of Example 3 with the prism portion developed in a straight line.
  • FIG. 8 is a linear optical path diagram showing the configuration of the imaging optical system of Example 4 with the prism portion developed in a straight line.
  • FIG. 9 is a straight optical path diagram showing the configuration of the imaging optical system of Example 5 with the prism portion developed in a straight line.
  • FIG. 10 is an aberration diagram showing spherical aberration, astigmatism, and distortion of the imaging optical system of Example 1.
  • FIG. 11 is an aberration diagram showing spherical aberration, astigmatism, and distortion of the imaging optical system of Example 2.
  • FIG. 12 is an aberration diagram showing spherical aberration, astigmatism, and distortion of the imaging optical system of Example 3.
  • FIG. 13 is an aberration diagram showing spherical aberration, astigmatism, and distortion of the imaging optical system of Example 4.
  • FIG. 14 is an aberration diagram showing spherical aberration, astigmatism, and distortion of the imaging optical system of Example 5.
  • the refractive index is the refractive index with respect to the wavelength of the d-line (587.56 nm).
  • Abbe number is nd, nF, nC and Abbe number is vd for d-line, F-line (486.13nm) and C-line (656.28nm), respectively.
  • FIG. 1 is an optical path diagram (optical path diagram at the wide angle end) showing a configuration example of the imaging optical system 10 according to the present invention.
  • the imaging optical system 10 is a bending optical system that forms an optical image of a subject on the light receiving surface (image surface) of the imaging element 19 after bending the optical path at a substantially right angle.
  • This is an optical system having a “positive / negative positive / positive” 5-group zoom configuration in which the lens group Grl to the fifth lens group Gr5 are sequentially arranged.
  • a diaphragm 101 is disposed between the second lens group Gr2 and the third lens group Gr3, an image sensor 19 for converting an optical image into an electrical signal is disposed on the image side, and a fifth lens.
  • a low-pass filter 18 is disposed between the group Gr5 and the image sensor 19.
  • the configuration of the optical system shown in FIG. 1 is the same as that of Example 1 described later.
  • the first lens group Grl includes a negative meniscus lens 11 that is disposed closest to the object side and is concave on the image side, a biconvex positive lens 12, and a prism 11 that is disposed between the lenses 11 and 12. It has a positive optical power as a whole and is fixed at the time of zooming.
  • the following is the second lens group Gr2 consisting of one biconcave negative lens 14 and moving during zooming, and the third lens group Gr3 consisting of a single positive meniscus lens 15 convex toward the object side and fixed during zooming.
  • It consists of a cemented lens 16 consisting of a biconvex positive lens 161 and a biconcave negative lens 162, and has a positive optical power as a whole, and a fourth lens group Gr4 that moves during zooming, and one biconvex positive lens force.
  • Fifth lens group that moves at the time of magnification Gr5 force The object-side force is also arranged sequentially along the optical axis AX.
  • the imaging optical system 10 has a larger distance between the first lens group Grl and the second lens group Gr2 during zooming from the wide-angle end to the telephoto end, and the third lens group Gr3 and the fourth lens group Gr4.
  • the distance between the fourth lens group Gr4 and the fifth lens group Gr5 is widened, and the distance between the fifth lens group Gr5 and the image sensor 19 is increased.
  • This is an optical system that performs a variable magnification operation.
  • the prism 13 included in the first lens group Grl is a right-angle prism having a reflecting surface 13c that bends the light beam substantially at a right angle. Accordingly, the subject light incident from the incident surface 13a of the prism 13 along the optical axis AX shown in FIG. 1 is bent at a substantially right angle by the reflecting surface 13c, is emitted from the output surface 13b, and is directed toward the image side. Guided linearly. Then, the subject light is guided to the light receiving surface of the image pickup device 19 through the mouth-pass filter 18 at an appropriate zoom ratio, and an optical image of the subject is picked up by the image pickup device 19.
  • the imaging optical system 10 to be covered is accommodated in a main body of a mobile phone or a digital camera, for example (described later with reference to FIG. 2).
  • the imaging optical system 10 that includes the prism 13 that bends the optical path at a substantially right angle in the first lens group Grl closest to the object side, the optical axis direction can be improved as compared with the imaging optical system of the conventional retractable structure.
  • the thickness can be reduced.
  • the member that forms the reflection surface that bends the optical path at a substantially right angle is not limited to the internal reflection type prism 13 shown in FIG. 1, but includes a surface reflection prism, an internal reflection plane mirror, a surface reflection plane mirror, and the like. Can be used. However, when the internal reflection prism is used, the subject light passes through the prism medium, so the surface interval when passing through the prism is shorter than the normal air interval depending on the refractive index of the medium. It becomes the conversion surface interval. For this reason, since an optically equivalent configuration can be achieved in a more compact space, it is desirable to employ an internal reflecting prism as the reflecting surface forming member.
  • any power of the incident surface 13a or the exit surface 13b of the prism 13 or both surfaces of the entrance surface 13a and the exit surface 13b may have optical power. Since the entrance surface 13a and the Z or exit surface 13b surface of the prism 13 have optical power, the imaging optical system 10 can be configured with a smaller number of parts.
  • the imaging optical system 10 of the present embodiment is a zoom lens system having a five-group zoom configuration of “positive / negative / positive / positive / positive” in order from the object side as described above.
  • a “positive / negative positive / positive” four-group zoom configuration that includes a prism in the lens group closest to the object side has been proposed.
  • the first lens group and the second lens group have strong negative combined power
  • the third lens group and the fourth lens group are strong!
  • Has positive composite power and the power arrangement as a whole becomes a retrofocus type .
  • the distance between the first lens group and the second lens group is widened to increase the convergence of the first lens group
  • the distance between the third lens group and the fourth lens group is widened to increase the second lens group.
  • the combined power of the fourth lens group from the lens group is weakened, and the power arrangement of the entire lens becomes a telephoto type.
  • the angle formed by the off-axis light beam passing through the first lens unit and the optical axis is reduced to reduce the lens diameter, while at the telephoto end, the overall length of the lens is shortened. Can be achieved.
  • the second lens group is the only group having negative power
  • the second lens group is used in order to set the Petzval sum to an appropriate value. It is necessary to provide strong negative optical power.
  • an aperture stop is generally disposed adjacent to the third lens group or the fourth lens group. Therefore, at the time of zooming, the incident height of off-axis rays incident on the second lens group does not change much, and the incident angle changes greatly. For this reason, in the “positive / negative positive / positive” four-group zoom configuration, the variation in aberration generated in the second lens group during zooming increases. In order to correct this aberration variation satisfactorily, the amount of movement of the second lens unit accompanying zooming needs to be an appropriate value.
  • the optical power of each lens group is increased as a method for reducing the overall length of the zoom lens system.
  • the amount of optical power of each lens unit is increased to reduce the overall length while keeping the amount of movement of the second lens unit appropriate,
  • the amount of magnification that the group carries increases.
  • aberration fluctuations accompanying zooming increase. Therefore, it becomes difficult to obtain good optical performance over the entire zoom region, and there is a limit to achieving full size miniaturization while maintaining good optical performance.
  • the fourth lens group closest to the image side of the “positive / negative / positive / positive” four-group zoom configuration is divided into two positive lens groups.
  • the zooming operation is performed by changing the air gap formed between the two divided positive lens groups (fourth and fifth lens groups) during zooming.
  • the magnification shift burden is shared by the two lens groups on the divided image side while keeping the movement amount of the second lens group at an appropriate value. Can do.
  • the imaging optical system 10 configured as described above satisfies the following conditional expressions (1) and (2).
  • dl2w Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the wide-angle end
  • dl2t Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the telephoto end.
  • conditional expression (1) and conditional expression (2) the ratio of the zoom ratio of the first lens group Grl to the fifth lens group Gr5 constituting the imaging optical system 10 is appropriate. Value, and the imaging optical system 10 in which further miniaturization is achieved while maintaining good performance over the entire zoom range is realized.
  • Conditional expression (1) defines the moving distance of the second lens group when the lens position changes from the wide-angle end state to the telephoto end state.
  • conditional expression (1) it is possible to satisfactorily correct aberration fluctuations in the second lens group Gr2. If the upper limit of conditional expression (1) is exceeded, the moving distance force S of the second lens group Gr2 will become smaller, and the tendency for the variable magnification burden of the second lens group Gr2 to decrease will become significant.
  • the second lens group Gr2 is the only negative lens group, so if the moving distance of the second lens group Gr2 is small, the variable magnification burden of the other lens groups Becomes larger.
  • the fourth lens group Gr4 which is a moving lens group
  • the moving distance of the fifth lens group Gr5 increases, making it difficult to make the entire length compact.
  • the movement distance of the second lens group Gr2 increases, so that the total length of the imaging optical system 10 tends to be significant.
  • aberration fluctuations accompanying zooming increase, and the difficulty of correcting aberration fluctuations by lenses in other lens groups increases. For this reason, it is difficult to obtain good optical performance over the entire zoom region of the imaging optical system 10.
  • Conditional expression (2) defines a condition for providing good optical performance over the entire zoom region within the range defined by conditional expression (1). In other words, it is for optimizing the ratio of the zooming amount that the fourth lens group Gr4 and the fifth lens group Gr5 carry.
  • the fifth lens group Gr5 By actively increasing the amount of magnification that the lens carries, the increase in aberration variation of the fourth lens group Gr4 that occurs when the overall length is reduced can be suppressed, and aberration variation at the time of magnification can be corrected well. It is possible to achieve both the miniaturization of the overall length and high optical performance.
  • the upper limit of conditional expression (2) If the upper limit of conditional expression (2) is exceeded, the amount of zooming handled by the fifth lens group Gr5 increases, so the tendency for aberration fluctuations in the fifth lens group Gr5 to increase becomes significant. In addition, during zooming, the decrease in the ambient light becomes obvious with a large change in the incident angle of the off-axis rays with respect to the image plane. On the other hand, if the lower limit of conditional expression (2) is not reached, the amount of zooming handled by the fifth lens group Gr5 becomes small, and it becomes difficult to sufficiently correct aberration fluctuations during zooming of the fourth lens group Gr4.
  • conditional expression (2) The significance of the conditional expression (2) will be described in more detail.
  • the off-axis rays pass when the lens unit moves from the wide-angle end to the telephoto end in order to satisfactorily suppress fluctuations in off-axis aberrations due to zooming to the telephoto end. It is important to increase the number of lenses whose height changes.
  • the height at which off-axis rays pass in the fourth lens group Gr4 and the fifth lens group Gr5 changes during zooming.
  • the fourth lens group Gr4 can correct off-axis light aberration at the wide-angle end
  • the fifth lens group Gr5 can correct off-axis light at the telephoto end.
  • the aperture 101 is a lens installed adjacent to the third lens group Gr3 or the fourth lens group Gr4. Generally, it is installed adjacent to. Therefore, at the time of zooming from the wide-angle end to the telephoto end, as the fourth lens group Gr4 moves toward the object side, the exit pupil moves toward the image plane side, and the incident when the off-axis chief ray enters the image plane. The angle increases.
  • the image sensor 19 installed on the image plane has a lower light intensity incident on the light receiving element in the pixel when the incident angle of the light beam on the pixel is larger, so the illuminance at the periphery of the image plane is reduced (peripheral Light drop).
  • the angle at which the off-axis ray forms the optical axis can be reduced. It is possible to suppress the decrease.
  • conditional expression (2) when the fourth lens group Gr4 moves to the object side during zooming, the fifth lens group Gr5 can move to the image side, thereby suppressing the change in the incident angle with respect to the pixel. Therefore, it is possible to prevent a decrease in illuminance at the periphery of the image due to zooming.
  • conditional expression (1) satisfies the following conditional expression (1) ′.
  • conditional expression (2) satisfies the following conditional expression (2) ′.
  • the second lens group Gr2 may be composed of a plurality of lenses, but is desirably composed of a single negative lens 14 as illustrated in FIG. In this case, it is desirable that one or both surfaces of the negative lens 14 be aspherical. Reducing the number of lenses in each lens group as much as possible directly leads to shortening the overall length of the imaging optical system 10.
  • the imaging optical system 10 can be made compact.
  • the second lens group Gr2 is a moving lens that is moved during zooming, but it is possible to reduce the burden on the driving unit that drives the second lens group Gr2.
  • the zooming load of the second lens group Gr2 is small, so even if the second lens group Gr2 is configured with one negative lens 14, high optical performance can be achieved. It is possible to maintain performance.
  • Nd2 Refractive index of negative lens 14 at d-line
  • V 2 Abbe number of negative lens 14
  • Nd Refractive index of prism 13 at d-line
  • the degree of contribution of the prism 13 to the compactness of the imaging optical system 10 can be increased. If the refractive index of the prism 13 is below the range of the conditional expression (5), the contribution to the compactness must be small, and the tilt angle of the chief ray in the prism becomes large, especially in the shortest focal length state. Since the total reflection conditions are approached, the loss of light quantity is undesirably increased. Furthermore, it is desirable that the viewpoint power for further compactness of the imaging optical system 10 is Nd that satisfies the following conditional expression (5) ′.
  • the third lens group Gr3 may be composed of a plurality of lenses, but as illustrated in FIG. 1, it is composed of a single positive lens (positive meniscus lens 15). Is desirable. In this case, it is desirable to satisfy the following conditional expression (6).
  • N3d Refractive index at d-line of positive-mass lens 15
  • the imaging optical system 10 can be made compact. Further, if the value falls below the range of conditional expression (6), the curvature of the positive meniscus lens 15 becomes strong, and the aberration fluctuation during zooming becomes large. This makes it difficult to obtain good performance over the entire zoom area. From the viewpoint of further reducing the aberration variation and further improving the optical performance, it is desirable that N3d satisfies the following conditional expression (6) ′.
  • the lens group moved during focusing is the fifth lens group Gr5. Since the fifth lens group Gr5 has a positive power, the infinite force can be focused to a short-distance object point by extending it toward the object side. At this time, at the same subject distance, the amount of extension is small at the wide-angle end, and the amount is extended at the telephoto end. The amount will increase. In the 5-group zoom configuration of “positive / negative / positive / positive”, the distance between the fourth lens group Gr4 and the fifth lens group Gr5 increases monotonously when zooming from the wide-angle end to the telephoto end. Focusing can be performed without increasing the overall length.
  • the imaging optical system 10 shown in FIG. 1 it is desirable to dispose one positive lens (biconvex positive lens 12) on the image plane side of the prism 13 in the first lens group Grl. Thereby, the chromatic aberration generated in the lens 11 can be corrected satisfactorily.
  • the biconvex positive lens 12 is formed with an aspherical shape in which the positive refractive power becomes weaker toward the periphery.
  • a lens group including the prism 13 (first lens group Grl) is fixed, and a lens group (second, third, and fifth lenses) that performs a zoom operation.
  • the groups Gr2, Gr3, Gr5) are provided between the prism 13 and the image sensor 19. If the lens group including the prism 13 is moved, the drive system becomes complicated and the optical axis may be shifted. Further, in general, the zoom optical system has a tendency that the total length of the lens tends to be long. There is also an advantage that the total length can be shortened by applying the present invention.
  • the reflecting surface 13c of the prism 13 is a flat surface from the viewpoint of ease of manufacturing the prism 13 and other lenses, and the entire imaging optical system 10 has a coaxial system configuration. It is desirable that If the reflecting surface 13c is a curved surface, the optical system will be decentered as a whole, so asymmetric distortion and field curvature will occur and other optical surfaces will also use special surfaces with asymmetric shapes to correct them. Need to be done. For this reason, if the manufacturing difficulty level is increased, it is not desirable because the difficulty level is increased for the evaluation and adjustment at the time of installation, and the manufacturing cost is increased.
  • a mechanical shutter having a function of shielding light from the imaging element 19 may be disposed instead of the optical aperture 101.
  • a powerful mechanical shutter is effective in preventing smearing when a CCD (Charge Coupled Device) type image sensor 19 is used, for example.
  • a driving source for driving each lens group diaphragm, shutter, etc. provided in the imaging optical system 10
  • a conventionally known cam mechanism or stepping motor can be used. Also move If the amount is small or the weight of the drive group is light, if an ultra-small piezoelectric actuator is used, each group can be driven independently while suppressing an increase in volume and power consumption of the drive unit. This is possible, and further compactness of the imaging lens device including the imaging optical system 10 can be achieved.
  • a low-pass filter 18 is interposed between the fifth lens group Gr5 and the image sensor 19.
  • the low-pass filter 18 is a parallel plate-like optical component having a specific cutoff frequency for adjusting the spatial frequency characteristics of the imaging optical system 10 and eliminating color moire generated in the imaging device 19.
  • Examples of the low-pass filter 18 include a birefringent low-pass filter formed by laminating a birefringent material whose crystal axis is adjusted in a predetermined direction, a wave plate that changes the polarization plane, and the like, and a required optical filter.
  • a phase-type low-pass filter or the like that realizes a good cutoff frequency characteristic by a diffraction effect can be applied.
  • the low-pass filter 18 does not necessarily have to be provided, but an infrared cut filter that reduces noise included in the image signal of the image sensor 19 may be used. Further, the surface of the optical low-pass filter 18 may be provided with an infrared reflection coating, and both filter functions may be realized by one.
  • the image sensor 19 photoelectrically converts the image signals of R, G, and B components to output to a predetermined image processing circuit in accordance with the light amount of the optical image of the subject imaged by the imaging optical system 10. It is a thing.
  • R (red), G (green), and B (blue) color filters are in a checkered pattern on the surface of each CCD of an area sensor in which a CCD (Charge Coupled Device) is two-dimensionally arranged. It is possible to use a single plate type color area sensor that is attached in the shape of a so-called V-shaped loose type.
  • CCD image sensors CMOS image sensors, VMIS image sensors, and the like can also be used.
  • the material of these optical members is not particularly limited as long as it is an optical member having a predetermined light transmittance and refractive index, and various glass materials and resin (plastic) materials can be used. However, if a plastic material is used, it is lightweight and can be mass-produced with an injection mold, etc., so that it is possible to reduce costs and reduce the weight of the imaging optical system 10 compared to the case of manufacturing with a glass material. Advantageous in terms of is there.
  • the optical member is made of a plastic material
  • various optical plastic materials such as polycarbonate and PMMA can be used as the plastic material.
  • plastic materials have a moisture absorption effect that combines with moisture in the air. If such moisture absorption occurs, optical properties such as refractive index may change due to moisture absorption even if prisms are manufactured as designed. is there. Therefore, by using a plastic material having a water absorption rate of 0.01% or less, the imaging optical system 10 that is not affected by moisture absorption can be constructed.
  • ZEONEX trade name of Nippon Zeon Co., Ltd.
  • the plastic material has a large refractive index change when the temperature changes! Therefore, if all the prisms and lenses constituting the imaging optical system 10 are made of plastic lenses, when the ambient temperature changes, There is a concern that the image point position of the imaging optical system 10 may fluctuate.
  • a lens for example, a glass mold lens
  • a plurality of prisms and The problem of temperature characteristics can be alleviated by using a refractive power distribution that cancels out some fluctuations in image point position during temperature changes between lenses.
  • the optical member is made of a plastic composite member.
  • a plastic composite member for example, a composite material in which fine particles of niobium oxide (Nb 2 O) of 30 nanometers or less are dispersed in a resin material such as acrylic.
  • a member formed by dispersing and blending inorganic fine particles in a plastic material, such as a composite member, can be used.
  • the temperature dependence of the plastic material and the inorganic fine particles can be used to prevent the refractive index from changing substantially, as described above, and the image point position fluctuation during the temperature change of the entire imaging optical system 10 can be reduced. It can be kept small.
  • the temperature change A of the refractive index is expressed by the following equation (7) by differentiating the refractive index n with respect to the temperature t based on the equation of the one-lentz / Lorentz equation.
  • Inorganic material A (approximate value) [ ⁇ 0— S Z ° C]
  • FIG. 2 is an external configuration diagram of a digital camera 20 showing an embodiment of a digital device according to the present invention.
  • a camera-equipped mobile phone in addition to the digital camera, a camera-equipped mobile phone, a video camera, a digital video unit, a personal digital assistant (PDA), a personal computer, a mobile computer, or these Including peripheral equipment (mouse, scanner, printer, etc.).
  • PDA personal digital assistant
  • FIG. 2 (a) is a front view of the digital camera 20
  • FIG. 2 (b) is a rear view
  • FIG. 2 (c) is a top view.
  • the digital camera 20 has a thin rectangular shape, and has a main switch 21 on its upper surface, a mode switching switch 22 for switching an operation mode such as still image shooting or movie shooting, and for starting or stopping the imaging operation.
  • Shutter button 23 is arranged, a flash 24 and a lens window 25 serving as a subject light intake window are arranged on the front side, various operation buttons 26 including a cross key on the back side, and a zoom lever 27 for performing a zooming operation 27
  • a display unit 28 having a power of a liquid crystal monitor (LCD) and the like.
  • the zoom lever 27 is printed with “T” for telephoto and “W” for wide-angle, and when each print position is pressed, each zooming operation is instructed. ! /
  • This imaging lens device 29 is a lens barrel whose length does not vary even during zooming or focusing drive, that is, does not protrude to the outside of the body force of the main body, and the imaging element 19 is provided on the image plane side. -It is physically assembled.
  • FIG. 3 is a functional block diagram schematically showing the electrical functional configuration of the digital camera 20.
  • the digital camera 20 includes an imaging unit 30, an image generation unit 31, an image data buffer 32, an image processing unit 33, a drive unit 34, a control unit 35, a storage unit 36, and an iZF unit 37.
  • the imaging unit 30 includes an imaging lens device 29 and an imaging element 19.
  • the light beam from the subject is imaged on the light receiving surface of the image sensor 19 by the imaging optical system 10 and becomes an optical image of the subject.
  • the image sensor 19 converts the optical image of the subject imaged by the imaging optical system 10 into electrical signals (image signals) of R (red), G (green), and B (blue) color components.
  • B is output to the image generator 31 as an image signal of each color.
  • the image sensor 19 is a still image! / ⁇ is a moving image! /, Or one of the images is captured by the control unit 35, or the output signal of each pixel in the image sensor 19 is read (horizontal synchronization, vertical synchronization,
  • the imaging operation such as (transfer) is controlled.
  • the image generation unit 31 performs amplification processing, digital conversion processing, and the like on the analog output signal from the imaging device 19, and determines an appropriate black level for the entire image, ⁇ correction, and white balance. Image data of each pixel is generated from the image signal by performing known image processing such as adjustment (WB adjustment), contour correction, and color unevenness correction. The image data generated by the image generation unit 31 is output to the image data notifier 32.
  • the image data buffer 32 is a memory that temporarily stores image data and is used as a work area for performing processing described later on the image data by the image processing unit 33.
  • the image processing unit 33 is a circuit that performs image processing such as resolution conversion on the image data in the image data buffer 32. Further, the image processing unit 33 can be configured to correct aberrations that could not be corrected by the imaging optical system 10 as necessary.
  • the drive unit 34 starts from the control unit 35. The plurality of lens groups of the imaging optical system 10 are driven so as to perform desired zooming and focusing by the output control signal.
  • the control unit 35 is configured to include, for example, a microprocessor, and performs operations of the imaging unit 30, the image generation unit 31, the image data buffer 32, the image processing unit 33, the storage unit 36, and the IZF unit 37. Control. That is, the control unit 35 controls the imaging unit 30 to execute at least one of still image shooting and moving image shooting of a subject.
  • the storage unit 36 is a storage circuit that stores image data generated by still image shooting or moving image shooting of a subject, and includes, for example, a ROM (Read Only Memory) and a RAM. That is, the storage unit 36 functions as a memory for still images and moving images.
  • the IZF unit 37 is an interface that transmits / receives image data to / from an external device.
  • the IZF unit 37 is an interface that conforms to standards such as USB and IEEE1394.
  • An imaging operation of the digital camera 20 configured as described above will be described.
  • the control unit 35 controls the imaging unit 30 to take a still image.
  • an optical image is periodically and repeatedly formed on the light receiving surface of the image sensor 19, converted into image signals of R, G, and B color components, and then output to the image generator 31.
  • the image signal is temporarily stored in the image data buffer 32, subjected to image processing by the image processing unit 33, transferred to a display memory (not shown), and the subject image is displayed on the live view display 28. Is done.
  • a still image can be obtained. That is, the image data is stored in the storage unit 36 as a still image memory.
  • the mode switching switch 22 is selected to activate the moving image shooting mode.
  • the control unit 35 controls the imaging unit 30 to capture a moving image.
  • the subject image is displayed in live view on the display unit 28, and when the shutter button 23 is pressed, moving image shooting is started.
  • the frame image signal of the captured moving image is temporarily stored in the image data buffer 32, subjected to image processing by the image processing unit 33, transferred to the display memory, and guided to the display unit 28. If you press the shutter button 23 again, movie shooting will end.
  • the captured video is used as a memory for movies. All the storage units 36 are guided and stored.
  • FIG. 4 is a cross-sectional view (optical path diagram at the wide-angle end) taken along the optical axis (AX), showing the configuration of the imaging optical system 10A of the first embodiment.
  • FIG. 4 (and FIGS. 5 to 9) also shows an outline of the path (optical path) along which the light incident from the object side travels, and the center line of the optical path is the optical axis (AX).
  • FIG. 5 is a diagram showing a configuration of the imaging optical system 10A in which the prism (PR) in FIG. 4 is replaced with a lens (LP) having a function substantially equivalent to the prism.
  • LP lens
  • the imaging optical system 10A of Example 1 is composed of a first lens (L1) composed of a negative meniscus lens concave on the image side, a prism (PRZLP), and a biconvex positive lens in order from the object side on the optical path.
  • L1 a first lens
  • PRZLP prism
  • biconvex positive lens a biconvex positive lens
  • the first lens group (Grl) that consists of the second lens (L2) and has positive optical power as a whole, and the second lens group that consists of one third lens (L3) consisting of a biconcave negative lens ( Gr2), stop (ST), fourth lens (L4) consisting of a positive meniscus lens convex on the object side, third lens group (Gr3) consisting of a single lens, and fifth lens (L5 consisting of a biconvex positive lens) ) And a sixth lens (L6) composed of a biconcave negative lens, and a fourth lens group (Gr4) having a positive optical power as a whole, and a seventh lens composed of a biconvex positive lens ( L7) It has a fifth lens group (Gr5) consisting of one lens.
  • L3 consisting of a biconcave negative lens ( Gr2), stop (ST)
  • fourth lens (L4) consisting of a positive meniscus lens convex on the object side
  • third lens group (Gr3) consisting of
  • An image sensor (SR) is disposed on the image side of the fifth lens group (Gr5) via a plane parallel plate (PL).
  • the plane parallel plate (PL) corresponds to an optical low-pass filter, an infrared cut filter, a cover glass of an image sensor, or the like.
  • This imaging optical system 10A is a system in which incident light is bent at approximately 90 degrees by a prism (PR) and guided to an imaging element (SR). Note that the direction of arrow A in the figure corresponds to the thickness direction (front-rear direction) of the digital camera 20 shown in FIG.
  • the first lens group (Grl) and the third lens group (Gr3) are fixed, and the second lens group The group (Gr2), the fourth lens group (Gr4), and the fifth lens group (Gr5) move in the direction of arrow B in FIG.
  • the movement of these lens groups during zooming from the wide-angle end (W) to the telephoto end (T) is indicated by arrows ml to m5 in Fig. 5.
  • arrows ml to m5 In the arrows ml to m5, dotted arrows indicate fixed and solid arrows indicate movement.
  • the first lens group (Grl) and the third lens group (Gr3) are fixed at the time of zooming as indicated by dotted arrows ml and m3.
  • the second lens group (Gr2) is moved in the direction approaching the image side as indicated by the solid arrow m2
  • the fourth lens group (Gr4) is linearly moved in the direction approaching the object side as indicated by the solid arrow m4.
  • the fifth lens group (Gr5) is moved in the direction approaching the image side as indicated by the solid arrow m5.
  • the direction and amount of movement of these lens groups may vary depending on the optical power of the lens group, the lens configuration, and the like.
  • the imaging optical system 10A has a larger distance between the first lens group (Grl) and the second lens group (Gr2) when the wide-angle end (W) force is also changed to the telephoto end (T). While the distance between the lens group (Gr3) and the fourth lens group (Gr4) is narrow, the distance between the fourth lens group (Gr4) and the fifth lens group (Gr5) is widened, and the fifth lens group (Gr5) The zooming operation is performed so that the distance between the image sensor 19 and the image sensor 19 becomes narrower.
  • the light beam incident from the object side (subject side) in FIG. 4 enters the incident surface of the prism (PR) via the first lens (L 1), After being bent and reflected at approximately 90 degrees on the reflecting surface, it is emitted from the emitting surface. Then, the second lens (L2), the third lens (L3), the optical aperture (ST), the fourth lens (L4) to the seventh lens (L7) passed in order, and then passed through the parallel plane plate (PL). Thereafter, an optical image is formed on the light receiving surface of the image sensor (SR).
  • the optical image is converted into an electrical signal.
  • This electrical signal is subjected to predetermined digital image processing, image compression processing, etc. as necessary, and is recorded as a digital video signal in the storage unit 36 of the digital camera 20 as shown in FIG. 2, or by wire or wirelessly. Transmitted to other digital devices.
  • Tables 3 and 4 show construction data of each lens in the imaging optical system 10A according to Example 1.
  • Table 15 below shows respective numerical values when the conditional expressions (1) to (6) described above are applied to the imaging optical system 10A according to Example 1.
  • Table 3 shows, in order from the left, the number of each lens surface, the radius of curvature of each lens surface (unit: mm), wide angle end (W), intermediate point (M), and telephoto end (T).
  • M T blank in the top axis spacing indicates that it is the same as the value in the left W column.
  • the number ri (i l, 2, 3,...) Of each lens surface is the i-th lens surface counted from the object side as shown in FIG.
  • the surface thus formed is an aspherical surface (aspherical refractive optical surface or a surface having a refractive action equivalent to an aspherical surface). Since both surfaces of the optical diaphragm (ST) and the plane parallel plate (PL) and the light receiving surface of the image sensor (SR) are flat surfaces, their radii of curvature are ⁇ .
  • Such treatment is the same in the optical path diagrams (FIGS. 6 to 9) of other embodiments described later, and the meaning of the reference numerals in the drawings is basically the same as in FIG. However, it does not mean that they are exactly the same.
  • the lens surface closest to the object side is given the same symbol (rl).
  • the aspherical shape of the optical surface is as follows using a local orthogonal coordinate system (X, y, z) in which the vertex at the surface is the origin and the direction toward the object force image sensor is the positive direction of the z axis ( 8) Define with equation. 4 + Gh16
  • Spherical aberration LONGITUDINAL SPHERICAL ABERRATION
  • astigmatism ASTIGMATISM
  • distortion aberration of the imaging optical system 10A in Example 1 in the infinite focus state under the lens arrangement and configuration as described above is shown in order from the left side of Fig.10.
  • the upper graph shows aberrations at the wide-angle end (W)
  • the middle graph shows aberrations at the midpoint (M)
  • the lower graph at the telephoto end (T).
  • the horizontal axis of spherical aberration and astigmatism represents the displacement of the focal position in mm
  • the horizontal axis of distortion aberration represents the amount of distortion as a percentage (%) of the total.
  • the vertical axis of spherical aberration shows the force astigmatism and distortion shown by the standard value of the incident height
  • the vertical axis of distortion shows the image height (image height, unit mm).
  • the diagram of spherical aberration shows red (wavelength 656.27nm) as a dashed line, yellow (so-called d-line; wavelength 587.56nm) as a solid line, and blue (wavelength 435.83nm) as a dashed line
  • red wavelength 656.27nm
  • d-line wavelength 587.56nm
  • blue wavelength 435.83nm
  • T the broken line
  • T represents the tangential (meridional) image plane in terms of the deviation (horizontal axis, unit mm) in the optical axis (AX) direction from the paraxial image plane.
  • the solid line (S) represents the sagittal (radial) image plane in terms of the amount of deviation (horizontal axis, unit mm) in the optical axis (AX) direction from the paraxial image plane. Further, the graphs of astigmatism and distortion are the results when the yellow line (d line) is used.
  • the imaging optical system 10A of Example 1 has a wide-angle end (W) and an intermediate point.
  • Example 2 In both (M) and the telephoto end (T), spherical aberration, astigmatism, and distortion are sufficiently suppressed, and excellent optical characteristics are exhibited.
  • the focal lengths f (mm) and F values at the wide angle end (W), the midpoint (M), and the telephoto end (T) in Example 1 are shown in Table 13 and Table 14 below, respectively. From these tables, it is clear that a bright optical system can be realized!
  • Example 2
  • FIG. 6 is a cross-sectional view of the configuration of the imaging optical system 10B according to the second embodiment, taken along the optical axis (AX).
  • the imaging optical system 10B of Example 2 includes, in order from the object side on the optical path, a first lens (L1) including a negative meniscus lens concave on the image side, a prism (LP), and a biconvex positive lens.
  • An image sensor (SR) is disposed on the image side of the fifth lens group (Gr5) via a parallel plane plate (PL).
  • the configuration of the lens groups is substantially the same as in Example 1 above, and the movement of each lens group during zooming from the wide-angle end (W) to the telephoto end (T) (see arrows m 1 to m in FIG. 6).
  • m5) is the same as in Example 1.
  • Tables 5 and 6 show construction data of each lens in the imaging optical system 10B according to Example 2.
  • FIG. 7 is a cross-sectional view of the configuration of the imaging optical system IOC according to the third embodiment, taken along the optical axis (AX).
  • the imaging optical system 10C of Example 3 includes, in order from the object side on the optical path, a first lens (L1) composed of a negative meniscus lens concave on the image side, a prism (LP), and a biconvex positive lens.
  • Second lens (L2) consisting of a first lens group (G rl) having a positive optical power as a whole and a third lens (L3) consisting of a biconcave negative lens Group (Gr2), Aperture (ST), Fourth lens (L4) consisting of a positive meniscus lens convex on the object side Third lens group (Gr3) consisting of a single lens, Fifth lens consisting of a biconvex positive lens (L5) and a sixth lens (L6) consisting of a biconcave negative lens, a fourth lens group (Gr4) with positive optical power as a whole, and a seventh lens consisting of a biconvex positive lens
  • the lens (L7) has a fifth lens group (Gr5) composed of one lens.
  • An image sensor (SR) is disposed on the image side of the fifth lens group (Gr5) via a parallel plane plate (PL).
  • the configuration of the lens groups is substantially the same as in Example 1 above, and the movement of each lens group during zooming from the wide-angle end (W) to the telephoto end (T) (see arrows m 1 to m5) is the same as in Example 1.
  • Table 7 and Table 8 show construction data of each lens in the imaging optical system 10C according to Example 3.
  • FIG. 8 is a cross-sectional view of the configuration of the imaging optical system 10D according to Example 4, with the optical axis (AX) cut vertically.
  • the imaging optical system 10D of Example 4 includes, in order from the object side on the optical path, a first lens (L1) composed of a negative meniscus lens concave on the image side, a prism (LP), and a biconvex positive lens.
  • the third lens group (Gr3) is the cemented lens force of the fifth lens (L5) consisting of a biconvex positive lens and the sixth lens (L6) consisting of a biconcave negative lens, and has a positive optical power as a whole.
  • the fifth lens group (Gr5) is composed of a lens group (Gr4) and a seventh lens (L7) composed of a biconvex positive lens.
  • An image sensor (SR) is disposed on the image side of the fifth lens group (Gr5) via a plane parallel plate (PL).
  • the configuration of the lens groups is substantially the same as in Example 1 above, and the movement of each lens group during zooming to the wide-angle end (W) force telephoto end (T) (arrow m 1 m5 in Fig. 8). Is also the same as in Example 1.
  • Table 9 and Table 10 show construction data of each lens in the imaging optical system 10D according to Example 4.
  • FIG. 9 is a cross-sectional view of the configuration of the imaging optical system 10E according to Example 5 with the optical axis (AX) cut longitudinally.
  • the imaging optical system 10E of Example 4 includes, in order from the object side on the optical path, a first lens (L1) including a negative meniscus lens concave on the image side, a prism (LP), and a biconvex positive lens.
  • An image sensor (SR) is arranged on the image side of the fifth lens group (Gr5) via a parallel plane plate (PL).
  • the configuration of the lens groups is substantially the same as in Example 1 above, and the movement of each lens group during zooming from the wide-angle end (W) to the telephoto end (T) (see arrows m 1 to m5) is the same as in Example 1.
  • Tables 11 and 12 show construction data of each lens in the imaging optical system 10E according to Example 5.
  • Tables 13 and 14 show the focal length (unit: mm) and F value at (M) and telephoto end (T), respectively. From these tables, it can be seen that a bright optical system was realized as in Example 1.
  • Table 15 shows numerical values when the conditional expressions (1) to (6) are applied to the imaging optical systems 10B to: LOE according to Examples 2 to 5, respectively.
  • Table 1 shows a comparison between Examples 1 to 5 and Examples described in Patent Documents 1 to 3 described above.
  • the telephoto ratio is defined as [total length] ⁇ [focal length at wide angle end]. It can be said that the smaller the telephoto ratio, the more compact the imaging optical system.
  • the imaging optical systems of Patent Documents 1 to 3 are all out of the range of the conditional expression (2), and it can be seen that the telephoto ratio is increasing. That is, if the conditional expression (2) is not satisfied! /, The optical system is large! /.
  • the imaging optical systems 10A of Examples 1 to 5 described above since it satisfies the above conditional expressions (1) to (6) in the five-group zoom configuration of “positive / negative / positive / positive / positive”, it has excellent optical performance while being compact in overall length. .
  • An imaging optical system is an imaging optical system that includes a plurality of lens groups and is capable of zooming by changing the interval between the lens groups, in order from the object side.
  • a first lens unit that has a positive optical power, is fixed at the time of zooming, and includes a reflecting member that bends the optical axis at a substantially right angle, and has a negative optical power and moves in the optical axis direction.
  • a second lens group that is possible, a third lens group that has positive optical power, a fourth lens group that has positive optical power and is movable in the optical axis direction, and has positive optical power.
  • a fifth lens group movable in the optical axis direction, and satisfying the following conditional expressions (1) and (2).
  • dl2w Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the wide-angle end
  • dl2t Distance on the optical axis from the most image side surface of the lens in the first lens group to the most object side surface of the lens in the second lens group at the telephoto end.
  • the imaging optical system power as a zoom lens system Five lenses of “positive / negative / positive / positive” in order from the object side It is composed of groups.
  • the zoom lens system with the “positive / negative / positive / positive” 5-group configuration has a larger power for each lens group in order to make the overall length more compact than the “positive / negative / positive / positive” 4-group type. Even in this case, it is possible to satisfactorily suppress aberration fluctuations associated with zooming. This is advantageous in reducing the overall length of the imaging optical system. [0120] Further, by satisfying the conditional expressions (1) and (2), the ratio of the zoom ratio of each lens unit constituting the zoom lens system becomes an appropriate value, which is favorable over the entire zoom range. Further miniaturization can be achieved while maintaining performance.
  • Conditional expression (1) defines the moving distance of the second lens group when the lens position changes from the wide-angle end state to the telephoto end state, and satisfies the conditional expression (1) As a result, the aberration variation of the second lens group can be corrected satisfactorily. If the upper limit of conditional expression (1) is exceeded, the moving distance force S of the second lens group will become smaller, and the tendency to reduce the zooming load of the second lens group will become prominent. In the positive / negative / positive / positive five-group zoom configuration, the second lens group is the only negative lens group, so if the moving distance of the second lens group is small, the magnification burden on the other lens groups is large. Become.
  • the moving distance of the fourth lens group and the fifth lens group which are moving lens groups, increases, and it is difficult to make the overall length compact.
  • the lower limit of conditional expression (1) is not reached, the moving distance of the second lens group becomes large, and the total length of the imaging optical system tends to become large.
  • aberration fluctuations associated with zooming increase, and the difficulty of correcting aberration fluctuations with lenses in other lens groups increases. This makes it difficult to obtain good optical performance over the entire zoom area.
  • Conditional expression (2) defines conditions for providing good optical performance over the entire zoom region within the range defined by conditional expression (1).
  • the ratio of the zooming amount that the fourth lens group and the fifth lens group carry is not optimized. For this reason, when the power of each lens group is increased in order to achieve a compactness of the total length, the aberration variation in the fourth lens group increases and sufficient correction cannot be performed. There was a problem that Compactie could not be achieved as intended.
  • conditional expression (1) satisfies the following conditional expression (1) '.
  • conditional expression (2) satisfies the following conditional expression (2) ′.
  • the second lens group includes one negative lens, and the negative lens has at least one aspheric surface and satisfies the following conditional expressions (3) and (4).
  • Nd2 refractive index of the negative lens at the d-line
  • V 2 Abbe number of the above negative lens
  • the second lens group is the only group having negative power
  • the upper limit of conditional expression (3) is exceeded, the negative Petzval value of the second lens group
  • the force S decreases, and it becomes difficult to sufficiently correct the positive Petzval value in the other lens groups. For this reason, field curvature becomes remarkable, and good optical performance cannot be obtained.
  • the upper limit of conditional expression (4) is exceeded, it will be difficult to correct chromatic aberration.
  • the lower limit of conditional expressions (3) and (4) is not reached, there is currently no mold lens material with excellent versatility, which makes it difficult to manufacture.
  • conditional expressions (3) and (4) the viewpoint power to enhance the effect of suppressing the curvature of field and improve the correction performance of chromatic aberration is the following conditional expressions (3) 'and (4)'. It is desirable to satisfy.
  • the reflecting member has a prism force, and the prism satisfies the following conditional expression (5).
  • Nd Refractive index at d-line of the prism
  • the degree of contribution of the prism to the compactness of the imaging optical system can be increased. If the refractive index of the prism is less than the range of the conditional expression (5), if the contribution to the compactness becomes poor, it is not force, but the inclination angle of the principal ray in the prism becomes large, especially in the shortest focal length state. Therefore, it is not preferable because the light loss is increased because it approaches the total reflection condition.
  • Nd satisfy the following conditional expression (5) 'U.
  • the third lens group includes one positive lens and satisfies the following conditional expression (6).
  • N3d Refractive index of d-line of the positive lens
  • the imaging optical system can be made compact. If the range of conditional expression (6) is exceeded, the curvature of the positive lens constituting the third lens group will be Becomes stronger, so that aberration fluctuations during zooming increase. For this reason, it is difficult to obtain good performance over the entire zoom area.
  • N3d satisfies the following conditional expression (6) '.
  • an optical member made of a resin material is included, and the optical member is molded using a resin material formed by dispersing inorganic particles having a maximum length of 30 nanometers or less in a resin material. Desirable to be an optical member.
  • the rate change can be reduced. Therefore, the use of a resin material in which such inorganic particles are dispersed as an optical member (lenses and prisms constituting each lens group) used in the present invention allows the entire imaging optical system according to the present invention to be used.
  • the image point position variation due to environmental temperature changes can be suppressed by / J.
  • the fifth lens group Since the fifth lens group has positive power, it can be focused from infinity to a short-distance object point by extending it toward the object side. At this time, at the same subject distance, the amount of extension is small at the wide angle end, and the amount of extension is large at the telephoto end.
  • the distance between the fourth lens unit and the fifth lens unit increases monotonously during zooming from the wide-angle end to the telephoto end. Also increase the total length Focusing can be carried out without causing it to occur.
  • An imaging lens device includes the imaging optical system described above and an imaging element that converts an optical image into an electrical signal, and the imaging optical system includes a light receiving surface of the imaging element.
  • An optical image of the subject is assembled on the top so that it can be formed. According to this configuration, it is possible to provide a compact imaging lens device having excellent optical performance that can be mounted on, for example, a small digital camera or a portable information terminal.
  • a digital device includes the above-described imaging lens device and a control unit that causes the imaging lens device to perform at least one of photographing a still image and a moving image of a subject. It is characterized by doing. According to this configuration, a compact and highly precise digital device such as a small digital camera or a portable information terminal can be realized.
  • the present invention having the above-described configuration, it is possible to satisfactorily suppress aberration fluctuations associated with zoom even when the power of each lens group is increased in order to achieve a full length compactness.
  • a 5-group zoom configuration of “positive / negative / positive / positive” is adopted. Furthermore, it is configured so that the ratio of the zoom ratio burden of each lens group becomes an appropriate value. Accordingly, it is possible to provide an imaging optical system, an imaging lens apparatus, and a digital device equipped with the imaging lens apparatus having good optical performance over the entire zoom range while achieving a compact length.

Abstract

La présente invention concerne un système optique de formation d'image avec une structure de zoom à cinq groupes 'positif-négatif-positif-positif-positif' offrant des prestations optiques élevées en dépit de sa compacité. Le système optique de formation d'image comporte, dans l'ordre à partir du côté objet, un premier groupe de lentilles de puissance optique positive, fixe lors de l'opération de variation du grossissement, et incluant un élément de réflexion pour fléchir l'axe optique à un angle droit ; un deuxième groupe de lentilles de puissance optique négative et mobile dans la direction de l'axe optique ; un troisième groupe de lentilles de puissance optique positive ; un quatrième groupe de lentilles de puissance optique positive et mobile dans la direction de l'axe optique ; et un cinquième groupe de lentilles de puissance optique positive et mobile dans la direction de l'axe optique. La relation entre la focale du dispositif de formation d'image, la distance sur l'axe optique et la distance de focalisation du cinquième groupe de lentilles est déterminée de manière à ce que le rapport des degrés de variation de grossissement entre le quatrième groupe de lentilles et le cinquième groupe de lentilles soit optimisé.
PCT/JP2007/061783 2006-06-14 2007-06-12 Système optique de formation d'image, dispositif de lentille de formation d'image et appareil numérique WO2007145194A1 (fr)

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TWI663419B (zh) * 2016-05-16 2019-06-21 大陸商信泰光學（深圳）有限公司 成像鏡頭（十三）
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TWI704387B (zh) * 2020-03-05 2020-09-11 信泰光學（深圳）有限公司 成像鏡頭（四十四）

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