TW200807018A - Imaging optical system, imaging lens device, and digital apparatus - Google Patents

Abstract

An imaging optical system with a "positive-negative-positive-positive-positive" five-group zoom structure having high optical performance despite its compactness. The imaging optical system has, in order from the object side, a first lens group having positive optical power, fixed in magnification varying operation, and including a reflection member for bending the optical axis at a right angle; a second lens group having negative optical power and movable in the optical axis direction; a third lens group having positive optical power; a fourth lens group having positive optical power and movable in the optical axis direction; and a fifth lens group having positive optical power and movable in the optical axis direction. The relationship between the focal length of the imaging device, the distance on the optical axis, and the focusing distance of the fifth lens group is determined so that the ratio of the amounts of variation in magnification between the fourth lens group and the fifth lens group is optimized.

Description

200807018 (1) EMBODIMENT OF THE INVENTION [Technical Fields of the Invention] The present invention relates to an imaging optical system that constitutes a variator lens system, and an imaging lens device including the imaging optical system, and the imaging lens device Digital machine. [Prior Art]

In recent years, digital cameras such as digital still cameras, digital video cameras, or camera-equipped mobile phones or personal digital assistants (PDAs) have become increasingly popular. The imaging elements mounted on these devices are highly pixelated and high. Functionalization is rapidly progressing. Therefore, in order to sufficiently exhibit the performance of an image pickup element such as high pixel, an imaging optical system in which a subject is imaged on the image pickup element is required to have high optical performance. Specifically, the single focus type is required to be an auto focus type, and the zoom function is also required to replace the digital zoom or to add an optical zoom. On the other hand, it is generally expected to be sophisticated on digital machines for good portability. Therefore, the imaging optical system is also required to be refined. However, if it is attempted to reduce the size and size of the imaging optical system for the sake of precision, it is difficult to maintain good optical performance. Therefore, as a solution for maintaining high optical performance and ingenuity, a crucible having a reflecting surface is inserted into the optical path to bend the optical path to a right angle, thereby miniaturizing the thickness in the optical axis direction (thin meat). The camera optical system is gaining popularity. In such a zigzag type of imaging optical system, Patent Document 4 - 200807018 (2)

The Department of Imaging revealed the imaging optics of the variable power lens system. Japanese Laid-Open Patent Publication No. 2003-202500 discloses a four-group zoom configuration of a lens group in which "positive and negative" optical power is sequentially arranged from the object side, and sequentially arranges "positive and negative positive" optical power. In the five-group variable magnification configuration of the lens group, the first lens group includes a variator lens system for bending the optical axis at a right angle. It is also disclosed in Japanese Laid-Open Patent Publication No. 2004-34771, that the first lens group includes a five-group variable magnification of "positive and negative positive" of the meandering 稜鏡. Japanese Patent Publication No. 2005-33 8 1 43 discloses that the first lens group includes five groups of times of "positive and negative positive" of a meandering yoke having a refractive index of 1.9 or more, and is changed. When the time is doubled, the variator lens that moves the second, fourth, and fifth lens groups is used. As is generally known, in order to achieve miniaturization of the variator lens system, it is effective to increase the power of each lens group constituting the variator lens system. However, when the ratio of the variable magnification of each lens group is to be maintained, and the power of each lens group is increased to reduce the total length of the variator lens system, the aberration variation at the time of zooming increases with the reduction. It is difficult to obtain good optical performance in the entire field of zooming. In the four-group zoom structure of "positive and negative positive" disclosed in Japanese Laid-Open Patent Publication No. 2003-202500, it is intended to increase the amount of magnification that each lens group is subjected to, thereby achieving a variable power lens system. In the miniaturization of the full length, it is difficult to correct the aberration variation caused by the magnification change. Therefore, the miniaturization of the variator lens system has a limit. On the other hand, if the five-group variable magnification configuration of "positive and negative positive" disclosed in the above three patent documents is reduced, the magnification load of each lens group can be reduced, so that the magnification change can be suppressed. -5- 200807018 (3) Aberration changes. However, in the above-mentioned three patent documents, it is not necessary to specifically describe the measures necessary for suppressing an increase in aberration variation caused by miniaturization of the entire length of any variator lens system. In other words, in the five-group variator lens system in which "three positive and negative positive" are disclosed in the above-mentioned three documents, H is not optimized due to the variable magnification of each lens group at the time of magnification change. When the total length of the variator lens is shortened, the power fluctuation of each lens group increases, and the aberration variation of φ at the time of magnification becomes larger. Therefore, it is impossible to obtain good performance across the entire zooming field, and its ingenuity has limits. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging optical system, an imaging lens device, and a digital device equipped with the imaging lens device which are compact and have high optical performance.

An imaging optical system according to one aspect of the present invention is an imaging optical system which is formed by a plurality of lens groups and which can be multiplied by changing a lens group interval, and is characterized in that: a lens group having positive optical power, fixed at magnification, and including a reflecting member that bends an optical axis into a substantially right angle; and a second lens group having negative optical power in the optical axis direction Moving; and a third lens group having positive optical power; and a fourth lens group having positive optical power movable in the optical axis direction; and a fifth lens group 'having positive optical power' Moving in the direction of the optical axis; the conditional expressions (1) and (2) below are satisfied. 15&lt; (TL*ft)/( | dl2t-dl2w | *fw)&lt; 45 · · · (1) -6 - (2) 200807018 (4) 0.45&lt; (β 5t*fw)/(/3 5w * ft) < 0.9 · · · where fw is the side of the entire imaging optical system at the wide-angle end: the focal length dl2w of the entire imaging optical system at the telephoto end: the wide-angle end is from the surface of the first lens group to the image surface side. The distance dl2t on the optical axis from the surface of the Ί of the lens in the second lens group: the surface of the lens at the telephoto end from the surface of the first lens group φ to the image surface side, to the surface of the lens in the second lens group The distance TL on the optical axis until the most object side of the imaging optical system, the distance on the optical axis / 3 5w: the imaging magnification of the 5-lens group when the subject distance is infinity / 3 5t: imaging magnification of the 5-lens group when the subject distance is infinity. The imaging lens device according to another aspect of the present invention, ν has an imaging optical system of the upper sS, and converts the optical image into an electrical image element; The imaging optical system is assembled so that an optical image of the subject can be formed on the front light receiving surface. According to still another aspect of the present invention, the digital camera includes: an upper imaging lens device; and a control unit that causes at least a still image and a moving image of the subject to be formed on the front surface. The object, the features and the advantages of the present invention are characterized by the fact that the most object side of the lens on the most object side of the lens of the I-distance lens is calculated from the most object side of the lens to the telephoto end of the wide-angle end. The characteristics of the imaging element are as follows, with the lens device being photographed in detail, the details of 200807018 (5) and the drawing surface are more clearly understood. [Embodiment] Hereinafter, embodiments of the present invention will be described based on the drawings. In addition, the following explanations and terms used in the chart are defined as follows. (a) The refractive index is a refractive index for the wavelength of the d line (587.56 nm).

(b) The Abbe number is such that the refractive indices of the d-line, the F-line (48 6.1 3 nm), and the C-line (656.28 nm) are nd, nF, and nC, respectively, and when the Abbe number is vd, vd = ( Nd-l)/(nF-nC) corresponds to the Abbe number vd obtained by the definition. (c) The expression of the surface shape is expressed based on the paraxial curvature. (d) Regarding the lens, when the expression "concave", "convex" or "crescent" is used, these descriptions are regarded as representing the shape of the lens near the optical axis (near the center of the lens) (based on paraxial curvature) Expression). &lt;Description of Configuration of Imaging Optical System&gt; [Fig. 1] An optical path diagram (optical path diagram at the wide-angle end) of a configuration example of the imaging optical system 10 according to the present invention. The imaging optical system 10 is a meandering optical system in which the optical path is bent at a substantially right angle and the optical image of the subject is formed on the light receiving surface (image surface) of the imaging element 15 , and the first arrangement is performed from the object side. The lens group Gr1 to the fifth lens group Gr5 are optical systems of the five groups of "positive and negative positive and positive" of 200807018 (6) times. Further, the aperture 1 0 is disposed between the second lens group Gr2 and the third lens group Gr3, and the imaging element 1 9 that converts the optical image into an electrical signal is disposed on the image side, and then the fifth lens group Gr5 and A low-pass filter 18 is disposed between the image pickup elements 19. Further, the configuration of the optical system shown in Fig. 1 has the same configuration as that of the first embodiment to be described later.

The first lens group Gr1 is a negative meniscus lens 11 that is disposed on the most object side and is recessed toward the image side, and a double convex positive lens 12, and is disposed between the lenses 1 1 and 1 2 . It is made of 1 1; it has positive optical power as a whole, and is fixed at the time of zooming. Hereinafter, the second lens group Gr2 which is formed by one double concave negative lens 14 and moves at the time of magnification change, and the third lens fixed by the positive meniscus lens 15 which is convex toward the object side and which is fixed at the time of magnification change The lens group Gr3 is formed by the cemented lens 16 of the double convex positive lens 161 and the double concave negative lens 162, and has a positive optical power as a whole, and a fourth lens group Gr4 that moves at the time of magnification change; The fifth lens group Gr5 which is formed by the convex positive lens and moves at the time of magnification change is sequentially arranged from the object side along the optical axis AX. In addition, when the imaging optical system 10 is zoomed from the wide-angle end to the telephoto end, the interval between the first lens group Gr1 and the second lens group Gr2 is widened, and the third lens group Gr3 and the fourth lens group Gr4 are The interval between the fourth lens group Gr4 and the fifth lens group Gr5 is widened, and the interval between the fifth lens group Gr5 and the imaging element 19 is narrowed. The crucible 13 contained in the group Grl has a right angle 稜鏡 on one side of the reflecting surface 1 3 c which bends the light into a slightly right angle. Therefore, along the optical axis AX shown in Fig. 1, the -9-200807018 (7) subject light incident from the incident surface 1 3 a of the 稜鏡1 3 is bent by the reflecting surface 13c to a slightly right angle, from The exit surface 13b is emitted and guided linearly toward the image side. Then, the subject light is transmitted through the low-pass filter 18 to the light receiving surface of the image sensor 19 at an appropriate zoom ratio, and the optical image of the subject light is photographed by the image sensor 19. .

The imaging optical system 1 is housed in, for example, a mobile phone or a digital camera (which will be described later with reference to Fig. 2). By using the imaging optical system 1 〇 which bends the optical path at a substantially right angle to the first lens group Gr 1 on the most object side, there is an imaging optical system which is more retracted than the previous lens group. The thickness in the optical axis direction can be made thinner. Further, the member for forming the reflecting surface which bends the optical path to a slightly right angle is not limited to the internal reflection type 稜鏡1 shown in FIG. 1, and may be a surface reflection 稜鏡, an internal reflection plane mirror, or a surface reflection plane mirror. Wait. However, when the internal reflection 采用 is used, since the subject light passes through the enamel medium, the interplanar spacing through the cymbal varies with the refractive index of the medium, which is a more common air separation. Shorter conversion surface spacing. Therefore, since a more compact space can be used to achieve an optically equivalent structure, it is preferable to use an internal reflection as a reflecting surface forming member. Further, either the incident surface 13a or the exit surface 13b of the crucible 13 or the both surfaces of the incident surface 13a and the exit surface 13b may be provided with optical power. The plane of the incident surface 13a and/or the exit surface 13b of the crucible 13 is optically powered, and the imaging optical system 1 of the present embodiment can be configured with a small number of components, as described above from the object side. 10- 10° 200807018 (8) A variable-magnification lens system consisting of five groups of magnifications of positive and negative positive and positive. In the past, a four-group zooming configuration in which the right and left sides of the lens group which is the closest to the object side of the zigzag variator lens that bends the optical axis to a slightly right angle has been proposed. In the case of the four-group magnification of "positive and negative", the first lens group and the second lens group have strong negative synthesis power at the wide-angle end, and the third lens group and the fourth lens group have Strong positive synthesis power, overall, the power configuration is reverse focus type. On the other hand, in the distal end state, the interval between the first lens group and the second lens group is widened to enhance the convergence of the first lens group, and the interval between the third lens group and the fourth lens group is widened. In order to weaken the combined power of the second lens group to the fourth lens group, the power arrangement of the entire lens is a telephoto type. According to this configuration, at the wide-angle end, the angle between the off-axis beam and the optical axis of the first lens group can be reduced, and the lens aperture can be reduced in size. At the telephoto end, the total length of the lens can be shortened. On the other hand, in the four-group zoom configuration of "positive and negative", the second lens group is the only group having negative power, so that the Petzval sum can be made suitable, so the second part must be made. The lens group has a strong negative optical power. Further, in the four-group variable magnification configuration of "positive and negative correction", an aperture aperture is disposed adjacent to the third lens group number or the fourth lens group. Therefore, at the time of zooming, the incident high angle of the off-axis light beam incident on the second lens group hardly changes, and the incident angle largely changes. Therefore, under the four-group zoom configuration of "positive and negative", the aberration variation occurring in the second lens group at the time of zooming is large. In order to correct the aberration variation well, it is necessary to make the amount of movement of the second lens group due to the magnification become an appropriate flaw. -11 - 200807018 (9)

Incidentally, in the variator lens system, a method of increasing the optical power of each lens group is known as a technique for purifying the full length thereof. In the four-group zooming configuration of "positive and negative", the fourth lens group is obtained by keeping the amount of movement of the second lens group in an appropriate state and increasing the optical power of each lens group to reduce the overall length. The amount of magnification that is burdened will become larger. As a result, the aberration variation caused by the magnification is increased. Therefore, it is difficult to obtain good optical performance for all of the cross-over zooming fields, and there is a limit to achieving full-length miniaturization while maintaining good optical performance. On the other hand, in the five-group zoom configuration of "positive and negative positive", the fourth lens group having the most image side of the four-group magnification of "positive and negative positive" is divided into two positive lens groups. Composition. Further, by changing the air gap formed between the two divided positive lens groups (fourth and fifth lens groups) at the time of zooming, the zooming operation can be performed. In other words, in the five-group zoom configuration of "positive and negative positive", it is possible to share the variable magnification burden with the two lens groups on the divided image side while keeping the amount of movement of the second lens group at an appropriate level. . From the above, it can be seen that when the five-group variable magnification configuration of "positive and negative positive" is used, the power of each lens group is increased in order to achieve the full-length compactness as compared with the four-group variable magnification configuration of "positive and negative positive". At the time, the aberration variation caused by the magnification can be well suppressed. Therefore, it is advantageous to miniaturize the entire length of the imaging optical system 10 . In the imaging optical system 10 configured as described above, the relationship between the following conditional expressions (1) and (2) is employed. 15&lt;(TL*ft)/( | dl2t-dl2w | *fw)&lt; 45 · · · (1) 200807018 (10) 0.45&lt; (β' 5t*fw)/(/3 5w*ft)&lt; 0.9 · · · (2) where fw : the focal length of the entire imaging optical system at the wide-angle end ft: the focal length of the entire imaging optical system at the telephoto end d 1 2 w · the most image of the lens from the first lens group at the wide-angle end The distance on the optical axis from the side of the most object side of the lens in the second lens group from the side of the side

Dl2t : distance TL 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: imaging optical system The distance from the most object side to the image plane, the distance on the optical axis / 3 5w : the imaging magnification of the 5th lens group at the wide-angle end when the subject distance is infinity / 3 5t: the subject distance The imaging magnification of the 5th lens group at the telephoto end in infinity, in addition, the ^" in the equation represents the multiplication. The following are the same. In addition, by satisfying the conditional expression (1) and the conditional expression (2), it is possible to cross the load ratio of the first lens group Gr1 to the fifth lens group Gr5 constituting the imaging optical system 1〇. The zooming field maintains good performance throughout the world while achieving a more compact imaging optics 10. The conditional expression (1) defines the moving distance of the second lens group when the lens position state changes from the wide-angle end state to the distal end state. By satisfying the conditional expression (1), the aberration variation of the second lens group Gr2 can be satisfactorily corrected. When the upper limit of the conditional expression (1) is exceeded, the movement of the second lens group Gr2 is 200807018. (11) The distance is too small, and the tendency to reduce the magnification of the second lens group Gr2 becomes remarkable. In the five-group zoom configuration of "positive and positive positive", the second lens group Gr2 is the only negative lens group. Therefore, when the moving distance of the second lens group Gr2 is small, the variable load of the other lens groups becomes different. Big. Therefore, the moving distances of the fourth lens group Gr4 and the fifth lens group Gr5 belonging to the moving lens group are increased, and it is difficult to make the full length fine. On the other hand, when the lower limit of the conditional expression (1) is exceeded, the moving distance of the second lens group Gr2 is increased. Therefore, the tendency of the entire length of the imaging optical system 10 to become large becomes remarkable. In addition, the variation of the aberration caused by the magnification change becomes large, and the difficulty of correcting the aberration variation by the lens of the other lens group increases. Therefore, it is difficult to achieve good optical performance in all of the zooming fields of the imaging optical system 10 .

The conditional expression (2) is a condition that is specified in the range defined by the conditional expression (1) in order to have good optical performance across the entire zooming field. In other words, it is a condition that the ratio of the magnification of the fourth lens group Gr4 and the fifth lens group Gr5 is optimized, and the five-group magnification configuration of "positive and negative positive" is actively increased. By increasing the variation of the aberration of the fourth lens group Gr4 which is generated when the total length is reduced, the aberration variation of the fifth lens group Gr5 can be improved, and the aberration variation at the time of magnification can be well corrected. It also achieves full-length miniaturization and high optical performance. When the upper limit of the conditional expression (2) is exceeded, the amount of magnification of the fifth lens group Gr5 is increased. Therefore, the tendency of the aberration variation on the fifth lens group Gr5 to become large becomes remarkable. Further, at the time of zooming, the incident angle of the off-axis light beam on the image plane is increased, and the decrease in the peripheral light is remarkable. On the other hand, if it is lower than the conditional formula (2) -14-

When the lower limit of 200807018 (12) is smaller, the amount of magnification of the fifth lens group Gr5 is smaller, and the variation of the aberration when the magnification of the fourth lens group Gr4 is sufficiently corrected is affected by the conditional expression (2). More detailed instructions. In the magnification change, in order to satisfactorily suppress the variation of the aberration caused by the zooming from the wide-angle end to the telephoto end, the number of lenses whose beam passing height changes when the lens group moves from the wide-angle end to the telephoto end, In the field defined by the heavy-duty type (2), in the fifth lens group Gr5 of the fourth lens group, the height of the beam passing through the off-axis beam is changed, and the wide-angle end is The lens group Gr4 corrects the off-axis aberration, and at the telephoto end, the beam can be corrected by the fifth lens group Gr5. Therefore, even if the aberration of each lens group is large and the aberration variation due to the magnification is increased due to downsizing, the aberration correction function of the mirror group Gr4 and the fifth lens group Gr5 is divided. In order to correct the aberrations well. When the lower limit of the conditional expression (2) is exceeded, the amount of movement of the fifth lens group Gr5 is reduced when the magnification is increased from the wide-angle end. Therefore, the change in the position of the fifth lens group Gr5 outside the axis is reduced. Therefore, it is difficult to obtain the off-axis aberration occurring at the distal end, and good performance cannot be obtained. On the other hand, if the upper limit of the conditional expression (2) is exceeded, the change of the off-axis light beam through the fourth lens group Gr4 is reduced when the magnification is changed from the far end to the far end, and the off-axis aberration occurring at the wide angle end is suppressed. There is no good optical performance. Further, in the five-group zoom configuration of "positive and negative positive", as shown, the aperture 10 1 is generally adjacent to the third lens group Gr3 and is therefore difficult to set. The lens system is off-axis and off-axis. Article Gr4 and Hua. The off-axis light force with the beam will change to the fourth, and the far-end beam pass will be difficult to suppress at the optical wide-angle end position, Figure 1, or -15-200807018 (13)

It is provided adjacent to the fourth lens group Gr4. Therefore, when zooming from the wide-angle end to the telephoto end, the fourth lens group Gr4 moves toward the object side, and the exit pupil moves toward the image surface side, and the incident angle when the off-axis principal ray is incident on the image plane becomes large. Generally, when the incident angle of the light to the pixel is larger, the incident angle of the light incident on the pixel is smaller, and the illuminance at the peripheral portion of the image surface is lowered (the peripheral light is lowered). . By moving the fifth lens group Gr5 toward the image plane side when zooming from the wide-angle end to the telephoto end, the angle between the off-axis beam and the optical axis can be reduced, thereby suppressing the image surface periphery caused by the magnification change. The illumination of the department is reduced. When the conditional expression (2) is satisfied, when the fourth lens group Gr4 moves toward the object side when the fourth lens group Gr4 is moved, the movement of the fifth lens group Gr5 to the image side can suppress the change of the incident angle with respect to the pixel, thereby preventing the change. The illuminance on the peripheral portion of the pixel due to zooming is reduced. It is preferable that the relationship of the conditional expression (1) above is satisfied by the conditional expression of the following condition (1)' from the viewpoint of the more refined imaging optical system 10. 20&lt;(TL*ft)/( | dl2t-dl2w | *fw)&lt; 40 · · · (1) In particular, it is more desirable to satisfy the following condition (1). 25&lt; (TL*ft)/( | dl2t-dl2w | *fw)&lt; 40 · · · (1), Similarly, standing on the condition of the above-mentioned recording optical system 1 更加 more precise The relationship of the formula (2) is preferably a conditional expression satisfying the following (2)'. 0.5&lt; (/3 5t*fw)/(^ 5w*ft)&lt; 0.8 * · · (2)5 In particular, it is more desirable to satisfy the conditional expression of (2)" below. 0.6&lt; (β 5t *fw)/(yS 5w*ft)&lt;0.75 · · · (2)' • 16-200807018 (14) The second lens group Gr2 may be composed of a plurality of lenses, but as illustrated in Fig. 1, It is preferable that one negative lens 14 is formed. In this case, it is preferable that one surface or both surfaces of the negative lens 14 are aspherical surfaces. The number of lenses of each lens group is reduced as much as possible, which is directly involved in the imaging optical system. The total length of the cymbal is shortened. By forming the second lens group Gr2 in one piece, the imaging optical system 10 can be made fine. Further, the second lens group Gr2 is a lens that is moved when the magnification is changed, so that the driving can be reduced. By the way, in the five-group zoom structure of "positive and negative positive", in order to reduce the load of the second lens group Gi: 2, the second lens 14 is used to form the second one. In the case of the lens group Gr2, high optical performance can also be maintained. It is preferable that one negative lens 14 of the second lens group Gr2 is satisfied, and the conditional expressions (3) and (4) below are satisfied. 1.45 &lt; Nd2 &lt;1.8 ---(3) 45 &lt; y 2 &lt; 75 ---(4)

Here, Nd2: refractive index of the negative lens 14 on the d line ^ 2: If the Abbe number of the negative lens 14 exceeds the upper limit of the conditional expression (3), it is difficult to keep the Petzval and the appropriate enthalpy. In the imaging optical system, the second lens group Gr2 is the only group having a negative power. Therefore, if the upper limit of the conditional expression (3) is exceeded, the negative Petz's edge of the second lens group Gr2 becomes small. It is difficult to fully correct the positive Petzval of other lens groups. Therefore, the image curvature is remarkable, and good optical performance cannot be obtained. Further, if the upper limit of the conditional expression (4) is exceeded, it is difficult to correct the chromatic aberration. On the other hand, if it is lower than the lower limit of the conditional expressions (3) and (4), the molded lens material -17-200807018 (15) which is excellent in general efficiencies does not exist under the current conditions, so the negative lens 14 Manufacturing is difficult. With regard to the conditional expressions (3) and (4) above, from the viewpoint of improving the suppression effect of the field curvature and improving the correction performance of the chromatic aberration, the conditional expressions (3)' and (4) below are satisfied. "It is better. 1. 5 &lt; Nd2 &lt; 1.75 · · · (3), 50 &lt; y 2 &lt; 60 · · · (4),

Regarding 稜鏡1 3 described in the above, it is preferable to satisfy the conditional expression (5) below.

Nd &gt; 1.85 · (5) where Nd: the refractive index of the prism 13 on the d-line can be improved by using 稜鏡1 3 having a refractive index satisfying the range of the conditional expression (5). 3 brings the expectation of the precision of the imaging optical system 10 . If the refractive index of 稜鏡13 is lower than the range of conditional expression (5), not only is the lack of precision required, especially in the shortest focal length state, the inclination of the chief ray in the crucible becomes large, so it approximates The total reflection condition makes the light amount loss large, which is not preferable. In addition, from the viewpoint of the elaboration of the imaging optical system, it is more preferable to satisfy the conditional expression (5) below.

Nd &gt; 1.9 · (5) The third lens group Gr3 may be constituted by a plurality of lenses, but as illustrated in Fig. 1, one positive lens (positive meniscus lens 15) is configured as a comparison good. In this case, it is preferable to satisfy the conditional expression (6) below. N3d>1.7 · · · (6) where N3 d : refractive index of the positive meniscus lens 15 on the d line -18- 200807018 (16) The camera can be imaged by forming the third lens group Gr3' with one piece The optical system 10 is compact. When the range of the conditional expression (6) is lower than the range of the conditional expression (6), the curvature of the positive meniscus lens 15 is increased, so that the aberration variation at the time of magnification is increased. Therefore, it is difficult to obtain good optical performance across the entire zooming field. * In addition, it is more desirable to satisfy N3 d which satisfies conditional expression (6) ' below, from the viewpoint of further reducing the fluctuation of the preceding aberration and improving the optical performance. N3 d &gt; 1.75 · · · (6) 9 ^ It is preferable that the lens group that moves when refocusing in the imaging optical system 10 is the fifth lens group Gr5. Since the fifth lens group Gr5 has a positive power, it can be focused from infinity to a close object by sending 'to the object side'. At this time, under the same subject distance, the amount of delivery at the wide-angle end is small, and at the telephoto end, the amount of delivery is large. In the five-group variable magnification configuration of "positive and positive positive", the distance between the fourth lens group Gr4 and the fifth lens group Gr5 increases monotonously from the wide-angle end to the telephoto end. Therefore, at the telephoto end, Focusing can be performed without increasing the overall length. In the imaging optical system 1A shown in Fig. 1, it is preferable that one positive lens (double convex positive lens 12) is disposed on the image surface side of the cymbal 13 in the first lens group Gr1. Thereby, the chromatic aberration generated on the lens 11 can be satisfactorily corrected. At this time, the double convex positive lens 12 is preferably formed such that the aspherical shape which is weaker toward the periphery of the positive refractive power is preferable. Further, in the imaging optical system 1A shown in FIG. 1, the lens group (the first lens group Gr1) including the 稜鏡1 3 is fixed as a lens group for performing the magnification change operation (the second, third, and fifth transmissions). The groups Gr2, Gr3, and Gr5) are preferably provided between the 稜鏡1 3 and the imaging element 119. In the case of a configuration in which the lens group of -19-200807018 (17) containing 稜鏡1 3 is moved, the drive system becomes complicated and the optical axis deviation occurs. Further, in general, the variable power optical system tends to have a longer overall length of the lens, but the application of the present invention has the advantage that the overall length can be shortened.

Further, in the imaging optical system 1 ,, the reflection surface 1 3 c of the 稜鏡 13 is formed by a plane in view of the ease of manufacture of the 稜鏡 13 and other lenses, and the imaging optical system 10 is a whole system. Coaxial system configuration is ideal. If the reflecting surface 13c is a curved surface, since the whole becomes an eccentric optical system, asymmetric distortion or field curvature occurs, which is used to correct it, and other optical surfaces become special surfaces that must use an asymmetrical shape. Therefore, it is not ideal to improve the manufacturing difficulty, increase the difficulty in the evaluation and adjustment during assembly, and increase the manufacturing cost. Further, instead of the optical aperture 1 〇 1, the imaging optical system 1 改 can be replaced with a mechanical shutter having a function of shielding the imaging element 19. For example, when the CCD (charge coupled device) method is used as the image pickup element 19, the mechanical shutter can effectively prevent light leakage. A conventionally known cam mechanism or stepping motor can be used as a driving source for driving each lens group, diaphragm, shutter, or the like provided in the imaging optical system 10. In addition, when the amount of movement is small or the weight of the driving group is light, "If an ultra-small piezoelectric brake is used, the volume of the driving portion or the power consumption can be suppressed, and each group can be independently driven. The camera lens device of the system 10 is further refined. As illustrated in Fig. 1, between the fifth lens group Gr5 and the image sensor 19, a low-pass filter 18 is preferably present. Low-pass filter -20- 200807018 (18)

The mirror 18 has an optical unit of a parallel flat plate for adjusting the spatial frequency characteristics of the imaging optical system 1 , and solving the cutoff frequency of the color turbulence generated on the imaging element 19. As the low-pass filter 18, for example, a birefringent type low-pass filter in which a crystal axis is a birefringent material adjusted in a predetermined direction or a wavelength plate in which a polarizing surface is changed can be applied, or A phase type low-pass filter or the like that realizes a necessary optical cutoff frequency characteristic by a diffraction effect. In addition, the low-pass filter 18 is not necessarily required, and instead, an infrared cut filter that reduces the noise contained in the image signal of the image sensor 19 can be used instead. Even if an infrared reflective coating is applied to the surface of the optical low-pass filter 18, the two filter functions can be realized with one filter. The imaging element 197 is optically converted into image signals of R, G, and 成份 components in accordance with the amount of light of the image of the subject imaged by the imaging optical system 10, and is subjected to image processing circuits of the predetermined image processing circuit. Output. For example, as the imaging element 19, R (red), G (green), and B (blue) can be used on the surface of each CCD in which a CCD (Charge Coupled Device) is a two-dimensional area sensor. The color filter is attached to the western checkerboard pattern, which constitutes a single-plate color area sensor called Bayer. In addition to such a CCD image sensor, a CMOS image sensor, a VMIS image sensor, or the like can be used. Next, the material and manufacturing method of the cymbal and the lens (optical member) constituting the imaging optical system 1A will be described. The material of these optical members is not particularly limited, and any glass material or resin (plastic) material can be used as long as it has an optical component having a predetermined light transmittance or refractive index. However, if a plastic material is used, it is lighter and can be mass-produced by injection molding, etc., therefore -21 - 200807018 (19) Compared with the case of glass material, the cost or imaging optical system is suppressed. The lightweight aspect of 10 is advantageous.

Here, when the optical member is made of a plastic material, various optical plastic materials such as polycarbonate or PMMA can be used as the plastic material. Among them, it is preferable to select a plastic material having a water absorption rate of 〇 1 以下 or less. If the plastic material has a moisture absorption effect in combination with moisture in the air, and such moisture absorption occurs, even if a crucible or the like is formed according to the design, the optical characteristics such as the refractive index change due to moisture absorption. Therefore, by using a plastic material having a water absorption ratio of 0.01% or less, an imaging optical system 10 which is not affected by moisture absorption can be constructed. As such a plastic material, for example, ΖΕΟΝΈΧ (trade name of Sakamoto Co., Ltd.) can be used. By the way, the refractive index of the plastic material changes greatly when the temperature changes. Therefore, if the 稜鏡 and the lens constituting the imaging optical system 10 are all formed of plastic lenses, the imaging optical system 1 is changed when the ambient temperature changes. The position of the image point of the cockroach will have doubts about the change. In an image pickup unit in which the specification of the positional change of the image point cannot be ignored, a lens formed of a glass material (for example, a glass mold lens) and a plastic lens are mixed, and a plurality of ridges and a lens are subjected to refractive power distribution. The problem of temperature characteristics can be alleviated by making the image position change at the time of temperature change a certain degree of cancellation. Alternatively, it is preferable to constitute an optical member by using a plastic composite member having a small change in refractive index when the temperature changes. As such a plastic composite member, for example, a composite member in which fine particles of cerium oxide (Nb205) of 30 nm or less are dispersed in a resin material such as polyacrylate can be used by dispersing and mixing inorganic fine particles in a plastic material. Made into parts. Therefore, the refractive index change can hardly occur by using the temperature dependence of the plastic material and the inorganic fine particles as described above in -22-200807018 (20), and the imaging optical system 10 can be completely integrated with the image point when the temperature changes. The positional variation is suppressed to be small. Here, the temperature change of the refractive index will be described in detail. The temperature change A of the refractive index is expressed by the Lawrence Lorenz formula, and the refractive index η is differentiated by the temperature t, and can be expressed as the following formula (7).

(«2+2)(«2-1) 6» (-3α)+

Among them, α: linear expansion coefficient, and [R]: molecular refractive resin material, generally the contribution to the second term in the above formula (7) is smaller than the first term, and can be almost ignored. For example, in the case of a PMMA resin, the coefficient of linear expansion α is 7xl (T5, and if it is substituted into the above formula, it is Α = -1·2χ1 (Γ4[ /°C], which is roughly the same as the measured 値. In other words, the temperature change A of the refractive index of -1·2χ1 (Γ4[厂C] is lower, and the absolute pressure is less than 8xl (T5[ /°C], which is ideal; especially the absolute 値 is not full 6x1 (Γ5 [ / ° C] is more desirable. The temperature change A (= dn / dT) of the refractive index of the plastic material which may be applied in this embodiment is shown in Table 1. [Table 1] Plastic material A (approximate値) 〖1 〇-5/t ] Polyolefin -11 Polycarbonate-14 - 'The temperature of the refractive index of the inorganic material that may be applied in this embodiment -23- 200807018 (21) Degree change A (== Dn/dT), the symbol of the plastic material is opposite. Show it in Table 2 〇 [Table 2] ___ Inorganic material _ Α (approximate 値) n (T5 / ° C ] -- 1.4 ALON 11.11 __ 1 0 _ Diamond 1.0 Calcium Carbonate 0.7 Potassium Titanium Phosphate 1.2 Magnesium Aluminate 0.9 - Magnesium Oxide 1. 9 Quartz 1.2 Cerium Oxide 0.9 Oxidation 乙 B 0.8 ___ Tin Oxide 4.9

&lt;Description of Digital Apparatus in which an Imaging Optical System Is Mounted&gt; Next, a digital apparatus in which the imaging optical system 10 described above is incorporated will be described. Fig. 2 is a view showing an embodiment of a digital camera according to the present invention, which is an external configuration of a digital camera 20. In addition, in the present invention, the digital device includes, in addition to the pre-recorded digital camera, a mobile phone with a camera, a video camera, a digital video unit, a personal digital assistant (PDA), a personal computer, a portable computer, Or peripheral machines (mouse, scanner, printer, etc.). Fig. 2(a) is a front view of the digital camera 20, Fig. 2(b) is a rear view, and Fig. 2(c) is a top view. Digital camera 20 series is thin rectangular -24- 200807018 (22)

The main switch 21 is provided with a mode switch 22 for switching an operation mode such as still picture shooting or movie shooting, and a shutter button 23 for starting or stopping the image capturing operation. The flash unit 24 is disposed on the front side. The subject light is taken into the lens 窓 25 of the window; on the back side, various operation buttons 26 including a cross key, a variable magnification bar 27 for performing a magnification change operation, and a display unit 28 formed by a liquid crystal monitor (LCD) are provided. On the variable magnification bar 27, a "T" character indicating a far distance and a "w" character indicating a wide angle are printed, and each zoom operation can be instructed by pressing each print position. Then, inside the main body of the digital camera 20, an imaging lens device 29 and an imaging element 19 which are constituted by a zigzag variator lens system as shown in Fig. 1 are mounted. That is, the image pickup lens unit 29 is vertically assembled into the 'lens 窓 25 and coincides with the incident surface 1 3 a of the 稜鏡 13 shown in Fig. 1 . The image pickup lens unit 209 is integrally assembled when the length of the image pickup lens unit 9 is not changed, that is, the lens barrel that does not protrude from the main body, and the image pickup element 19 is integrally formed on the image side. The thinning of the digital camera 20 can be achieved by the image pickup lens unit 2 9 having such an optical path zigzag type. Fig. 3 is a block diagram showing the function of the electrical function of the digital camera 20. The digital camera 20 includes an imaging unit 30, a video generation unit 31, a video data buffer 3, a video processing unit 33, a drive unit 34, a control unit 35, a memory unit 36, and an interface. Department 3 consists of. The imaging unit 30' is provided with an imaging lens device 29 and an imaging element 19. The light from the subject is imaged on the light receiving surface of the image sensor 19 by the imaging optical system 1 and becomes an optical image of the subject η. -25- 200807018 (23) The imaging element 19 is an electrical signal that converts the optical image of the subject imaged by the imaging optical system 10 into color components of R (red), G (green), and B (blue). The image signal is output to the image generating unit 31 in the form of image signals of R, G, and B colors. The imaging element 197 controls the imaging of either the still picture or the animation or the reading of the output signals of the pixels in the imaging element 19 (horizontal synchronization, vertical synchronization, transmission) under the control of the control unit 35. ) The camera action.

The image generating unit 3 1 performs an amplification process, a digital conversion process, and the like on the analog output signal from the image sensor 19, and also performs appropriate black level determination, r correction, and white balance adjustment (WB adjustment) for the entire image. ), image correction such as contour correction and stain correction, and image data of each pixel is generated from the image signal. The image data generated by the image generating unit 31 is output to the video data buffer 32. The video data buffer 32 is used as a memory for the video data to be described later by the video processing unit 33, for example, by RAM ( R and 〇m Access Memory). The image processing unit 33 is a circuit for performing image processing such as resolution conversion on the image data of the image data buffer 32. Further, the image processing unit 33 may correct the aberration that cannot be corrected on the imaging optical system 10 as needed. The drive unit 34 drives the complex lens group of the imaging optical system 1 by the control signal output from the control unit 35 to perform the desired zoom and focus ’. The control unit 35 is configured by, for example, a microprocessor, and controls the imaging unit 30, the video generation unit 31, and the video data buffer 3, and the image processing -26 - 200807018 (24) part 3 3 The operation of each part of the portion 36 and the face portion 37. In other words, the control unit 35 can control the imaging of at least one of the still picture shooting and the moving picture of the subject, which is executed by the imaging unit 30. The δ 忆 部 3 6 ′ is a memory circuit for recalling image data generated by still picture photography or moving book photography of a subject, and is configured by, for example, H ROM (Read Only Memory) or RAM. That is, the memory unit 3 6 has a function as a memory for still painting and animation. The interface between the interface unit 3, 7' and the external device for transmitting and receiving video data is, for example, an interface based on specifications such as USB or IEEE 1 3 94.

The imaging operation of the digital camera 20 configured as described above will be described. When taking a still picture, first, the mode switching switch 22 is selected to activate the still picture mode. When the still picture shooting mode is activated, the control unit 35 controls the shooting of the still picture by the imaging unit 30. Thereby, the optical image is periodically imaged on the light receiving surface of the image sensor 19 and converted into image signals of R, G, and B color components, and then output to the image generating unit 31. The image signal is temporarily stored in the image data buffer 32, and is subjected to image processing by the image processing unit 33, and then transmitted to the display memory (not shown), and displayed on the display unit 28. Instantly display the subject image. When the shutter button 23 is pressed in this state, a still image can be obtained. That is, the image data is stored in the memory portion 36 as a memory of the still image. Further, when the movie shooting is performed, the mode switching switch 22 is selected to activate the movie shooting mode. Thereby, the control unit 35 controls the imaging unit 30 to perform imaging of the animation. At this time, the -27-200807018 (25) subject image is immediately displayed on the display unit 28, and the shutter image is started by pressing the shutter button 23. The frame image signal of the captured animation is temporarily stored in the image data buffer 32, and is subjected to image processing by the image processing unit 33, and then transmitted to the display memory and imported to the display unit. 28. Here, the animation photography ends by pressing the shutter button 23 again. The captured moving image is stored in the memory unit 36 as the memory for animation. φ &lt;Description of a more specific embodiment of the imaging optical system&gt; Hereinafter, the imaging optical system 1 shown in Fig. 1 is formed, that is, the imaging lens device 29 mounted on the digital camera 20 shown in Fig. 2 The specific configuration of the imaging optical system 1 〇 will be described with reference to the drawings. [Example 1]

Fig. 4 is a cross-sectional view (an optical path diagram at the wide-angle end) in which the optical axis (AX) is longitudinally sectioned, showing the configuration of the imaging optical system 10A of the first embodiment. In Fig. 4 (and Figs. 5 to 9), the traveling path (optical path) of light incident from the object side is also schematically illustrated, and the center line of the optical path is the optical axis (AX). Further, Fig. 5 is a configuration in which the 稜鏡 (PR) in Fig. 4 is replaced with an imaging optical system 10A in which a lens (LP) having a slightly equivalent function is used. Further, in the following embodiments 2 to 5, only the linear light path diagram corresponding to this Fig. 5 is shown, and the twisted optical path diagram is omitted. The imaging optical system 10A of the first embodiment has a first lens (L1) and a cymbal formed by a negative meniscus lens recessed toward the image side in order from the object side on the optical path. PR/LP), a second lens group 280-200807018 (26) (L2) made of a double convex positive lens, and a first lens group (Grl) having positive optical power as a whole, which is formed by a double concave negative lens The second lens group (Gr2) composed of the third lens (L3), the aperture (ST), and the fourth lens (L4) formed by the positive meniscus lens protruding toward the object side a third lens group (Gir3), a fifth lens (L5) made of a biconvex positive lens, and a cemented lens of a sixth lens (L6) formed by a double concave negative lens, and having a positive optical power as a whole The fourth lens group (Gr4) and the fifth lens group (Gr5) including the seventh lens (L7) formed of the double convex positive lens are configured. Then, on the image side of the fifth lens group (Gi: 5), the imaging element (SR) is disposed via the parallel plane plate (PL). The parallel plane plate (PL) corresponds to low optical efficiency. Through-filter, infrared cut-off filter, cover glass of camera elements, etc. In the imaging optical system i〇A, the incident light is bent into a prism (PR) to be slightly 90 degrees, and is introduced into the imaging element (sR). Further, the direction in which the arrow A is not shown in the drawing is in the thickness direction (front surface and rear direction) of the digital camera 20 shown in FIG. 2.

Here, the first lens group (Grl) and the third lens group (Gr3) are fixed, and the second lens group (Gr2), the fourth lens group (Gr4), and the fifth lens group (Gr5) are changing. When it is doubled, it will move in the direction of arrow B of FIG. The moving state '' of these lens groups when zooming from the wide-angle end (W) to the telephoto end (T) is as shown by arrows ml to m5 in Fig. 5 . In the arrows ml to m5, the dotted arrow indicates fixation, and the solid arrow indicates movement. The first lens group (Grl) and the third lens group (Gr3)' are fixed as indicated by the dotted arrows ml and m3, and are fixed at the time of magnification change. The second lens group (Gr2) moves toward the image side as indicated by the solid arrow m2; the fourth lens group -29-200807018 (27)

(Gr4) linearly moves toward the object side as indicated by the solid arrow m4, and the fifth lens group (Gr 5) moves toward the image side as indicated by the solid arrow m5. However, the following embodiments are also included, and the moving direction or amount of movement of these lens groups changes depending on the optical power of the lens group, the lens configuration, and the like. As a result, when the imaging optical system 10 A is zoomed from the wide-angle end (W) to the telephoto end (T), the interval between the first lens group (Grl) and the first lens group (Grl) is widened. The interval between the third lens group (Gr3) and the fourth lens group (Gr4) is narrowed, and the interval 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 in a narrower interval from the image pickup device 19. Further, the number ri (i=i, 2, 3, · · ·) shown in Fig. 5 is the i-th lens surface when the number is from the object side, and the ri is marked with * to indicate that the surface is non- Spherical. Further, the lens surface on the cemented lens constituting the fourth lens group (Gr4) is not only the two surfaces of the cemented lens as the lens surface but also the joint surface as one surface. With this configuration, the light incident from the object side (subject light) of FIG. 4 is incident on the incident surface of the 稜鏡 (PR) via the first lens (L1), and is curved at the reflection surface to be slightly 9 After being reflected at 0 degrees, it is emitted from the exit surface. Then, the second lens (L2), the third lens (L3), the optical stop (ST), and the fourth lens (L4) to the seventh lens (L7) are sequentially passed through the parallel plane plate (PL). An optical image is formed on the light receiving surface of the image sensor (SR). Then, in the imaging element (SR), the pre-recorded optical image is converted into an electrical signal. The electrical signal is subjected to digital image processing or image compression processing as required, and is digitally imaged and recorded in the memory unit 36 of the digital camera 20 of FIG. 2, for example, -30-200807018 (28) Transfer to other digital machines. The imaging optical system 10A of the first embodiment is shown in Tables 3 and 4. Further, the conditional expressions of the above-described conditional expressions (1 to 15° of the imaging optical system 10A described in Example 1 or the structural data lines 1) to (6) of the respective lenses by wire or wireless are applied to the number of executions, Post-release table

-31 - 200807018 (29) [Table 3]

Lens surface curvature radius 1 axis upper space (mm) refractive index Abbe number (mm) WMT r1 * OO 0.600 1.8467 23,82 r2 7.000 r3 CO 1.093 - r4 OO 4-744 1.9229 16.83 0.200 r5 * 3.983 1.579 1.7170 52.93 • r6 -39.658 0.35 K91 2.48 γ7 * -11.844 0.600 1.6184 57.79 r8 2.730 2· 73 1.17 0.60 γ9 (aperture) OO 0. 200 ΓΙΟ 5.413 0.766 1.8467 23.82 γ11 15.968 4.45 2.52 1.50 r!2* 4.485 1.884 1.7545 51.57 • r13 -5; 063 0.600 1.7741 24.77 r14 5.103 0.60 3.39 6.73 r15* 12.212 1/823 1-5305 55.72 r16* -6.322 3.78 2.92 0.60 rlT OO 0. 500 1-5187 64.00 r18 OO 0.500 r19 (image surface) OO -32 - 200807018 (30 [Table 4] Lens surface conic coefficient aspheric coefficient A Β CD Μ 0 9-263E-04 -4.306Ε-05 U151E-06 -L006E-08 r5 0 -2.108E-03 -4,966Ε-05 -2.607Ε- 06 - 2·Π5Ε-07 r7 0 4.S59E-03 -2.926Ε-04 -5.340Ε-05 1.136Ε-05 r12 0 -2.005E-03 9.60ΖΕ-05 -2.214Ε-05 1.406Ε-06 r15 0 5·733E-04 Κ580Ε-04 -2.441Ε-05 1.681Ε-06 r 16 0 2.067Ε-03 2.770Ε-04 -4,847Ε-05 2.969Ε-06

As shown in Table 3, the number of each lens surface from the left, the radius of curvature of each lens surface (unit: mm), the wide-angle end (W), the intermediate point (M), and the telephoto end (T) are infinity. The interval between the lens faces on the optical axis in the in-focus state (the space above the axis) (in mm), the refractive index of each lens, and the Abbe number. The space above the axis and the empty space of T indicate the same as the left W block. Here, the number ri (i = 1, 2, 3, · · ·) of each lens surface is the i-th lens surface from the object side as shown in Fig. 5, and the surface number marked with * after ri It represents an aspherical surface (a refractive optical surface of an aspherical shape or a surface having an equivalent refractive effect to an aspherical surface). Further, on both sides of the optical aperture (ST) and the parallel plane plate (PL), and the respective faces of the light receiving surface of the image pickup element (SR) are flat, the radius of curvature of these faces is 00. In this way, the same is true for the optical path diagram (Figs. 6 to 9) in the other embodiments to be described later, and the meaning of the symbols in the drawings is basically the same as that of Fig. 5. It's just that 'not exactly the same thing. For example, as shown in the figures, the lens faces closest to the object side are all labeled with the same symbol "1"' but this does not mean that their curvature etc. are implemented across The aspherical shape of the optical surface is a rectangular coordinate system in which the surface vertex is the origin, and the direction from the object-33·200807018 (31) to the imaging element direction is the positive direction of the z-axis. X, y, z), defined as follows (8). _ch^_ 1+SQRT (Bu (1+ 涵+Ah4 +Bh6 +Ch8 +Dh10 +Eh12 +Fh14 +Gh16 +Hh18+Jh20 · ••(8)

Where z: the position of the height h, the displacement in the z-axis direction (surface vertex reference) h : the height in the vertical direction for the z-axis (h2 = x2+ y2) c : the paraxial curvature (=1 / radius of curvature A, B, C, D, E, F, G, H, J: 4, 6, 8, 10, 12, 14, 16, 18, 20 aspheric coefficients k: cone coefficient from above ( As can be seen from the equation 8), the radius of curvature of the aspherical lens shown in Table 3 is 値 near the apex of the face of the lens. The above-described lens arrangement and configuration of the imaging optical system 10A according to the first embodiment are spherical aberration (LONGITUDINAL SPHERICAL ABERRATION), astigmatism (ASTIGMATISM), and distortion (DISTORTION) in an infinity focus state. , is shown in order from the left side of FIG. In the figure, the upper section indicates the wide-angle end (W), the middle section indicates the intermediate point (M), and the lower section indicates the aberration of the telephoto end (T). Further, the horizontal axis of the spherical aberration and the astigmatism represents the deviation of the focus position in mm units, and the horizontal axis of the distortion aberration is the ratio of the total amount to the total -34-200807018 (32) (%) To represent. Although the vertical axis of the spherical aberration is represented by 値 which is normalized and incident, the vertical axis of astigmatism and distortion is expressed by the height (image height, unit mm) of the image.

In the figure of spherical aberration, red (wavelength 656.27 nm) is indicated by a slight lock line, yellow (ie, d line; wavelength 5 8 7.5 6 nm) is indicated by a solid line, and then blue is indicated by a broken line (wavelength 43). 5.8 3 nm), using three kinds of photo-differences with different wavelengths. Further, in the astigmatism diagram, the broken line (T) indicates that the tangential (warp) image plane is shifted by the optical axis (AX) direction from the paraxial image plane (horizontal axis, unit mm). The solid line (S) expresses the radial image plane by the amount of shift (horizontal axis, unit: mm) in the optical axis (AX) direction from the paraxial image plane. Further, the graph of astigmatism and distortion is a result when the upper yellow line (d line) is used. As can be seen from FIG. 10, the imaging optical system 10A of the first embodiment is a spherical aberration, an astigmatism, and a distortion image regardless of the wide-angle end (W), the intermediate point (M), and the telephoto end (T). The difference is sufficiently suppressed to exhibit excellent optical characteristics. Further, the focal lengths f (mm) and F 时 at the wide-angle end (W), the intermediate point (M), and the telephoto end (T) in the first embodiment are shown in Tables 13 and 14 which will be disclosed later. As is apparent from these tables, in the present invention, a bright optical system can be realized. [Embodiment 2] Fig. 6 is a cross-sectional view showing the configuration of the imaging optical system 10B according to the second embodiment, which is a longitudinal section of the optical axis (AX). The imaging optical system 10B of the second embodiment has a first lens formed by a negative meniscus lens recessed toward the image side -35-200807018 (33) in order from the object side on the optical path. (L1), 稜鏡 (LP), a second lens group (L2) composed of a double convex positive lens and having a positive optical power, a first lens group (Grl), and a double concave negative lens 3 lens (L3) consisting of a second lens group (Gr2), a stop (ST), and a fourth lens (L4) formed by a positive meniscus lens protruding toward the object side. ♦ The third lens group (Gr3), the fifth lens (L5) formed by the double convex positive lens, and the cemented lens of the sixth lens (L6) formed by the double concave negative lens, and having positive optical power as a whole The fourth lens group (Gr4) and the fifth lens group (G r 5 ) composed of one piece of the seventh lens (L 7 ) formed by the double convex positive lens are configured. Then, on the image side of the fifth lens group (Gr 5), an imaging element (SR) is disposed via a parallel plane plate (PL). The configuration of the lens group is substantially the same as that of the first embodiment, and the movement state of each lens group when the width is changed from the wide-angle end (W) to the telephoto end (T) (arrows m 1 to m 5 in Fig. 6) Also shown is the same as in the first embodiment.

In the imaging optical system 1 〇B of the second embodiment, the structural data of each lens is shown in Tables 5 and 6. -36- 200807018 (34) [Table 5] Lens surface curvature radius Axis spacing (mm) Refractive index Abbe number (mm) WMT rl * CO 0.600 1.8070 25.95 r2 6.640 1.113 r3 OO 4.737 2.1400 24.00 γ4 oo 0.200 γ5 * 3.894 1.827 1.6299 58.10 r6 -15.515 0.31 1,94 2,58 γ7 Ben-10:429 0.600 1.5891 SI.24 r8 2.675 2.88 1.24 0.60 γ9 (aperture) &lt;x&gt; 0.000 ΠΟ 4. 570 0.600 2.1400 24,00 rll 7.456 3 · 71 2.19 1.50 r12 * 3· 584 1.889 L 7433 43.84 r13 -4·321 Ο.δΟΟ 1.7847 19.47 r14 3.806 0.71 2· 28 5-63 rl5 this 14.945 2.022 1.5305 55.72 rl6 * -4.919 3.31 2,66 0.60 rl7 oo 0.500 1.5187 64.00 r18 oo 0.500 r19 (image surface) oo -37- 200807018 (35) [Table 6] Lens surface conic coefficient aspherical number of grandchildren ABCD Γ1 0 9J52E-04 -6.157E-05 2.185E-06 -3.587E-08 R5 0 -2.649E-03 -5.426E-05 -3.213E-06 -3. 207E-07 r7 0 5.71SE-03 -3.461E-04 -7.386E-05 1.507E-05 Π2 0 -3.342E-03 1.262E-04 -3.307E-05 1.581E-06 rl5 0 7.539E-04 1.700E-07 -1.16ΪΕ-05 4.981E-07 r16 0 3.13 4E-03 2.961E-05 -1.968E-05 8.892E-07 [Embodiment 3]

Fig. 7 is a cross-sectional view showing the configuration of the imaging optical system 10C according to the third embodiment, which is a longitudinal section of the optical axis (AX). The imaging optical system 10 C of the third embodiment sequentially has a first lens (L1) and a cymbal formed by a negative meniscus lens recessed toward the image side from the object side on the optical path. (LP), a first lens group (Grl) composed of a second lens (L2) made of a biconvex positive lens and having positive optical power as a whole, and a third lens (L3) formed by a double concave negative lens 1 A third lens group (Gr2) composed of a sheet, a stop (ST), and a third lens group (Gr3) composed of a fourth lens (L4) formed by a positive meniscus lens protruding toward the object side (Gr3) a fourth lens group (Gr4) formed of a fifth lens (L5) formed by a double convex positive lens and a sixth lens (L6) formed by a double concave negative lens and having a positive optical power as a whole, And a fifth lens group (Gr5) composed of a seventh lens (L7) formed of a double convex positive lens. Then, on the image side of the fifth lens group (Gr5), an imaging element (SR) is disposed via a parallel plane plate (PL). The configuration of the lens group is substantially the same as that of the first embodiment, and the movement state of each lens group when the magnification is changed from the wide-angle end (W) to the telephoto end (T) (arrows m 1 to m 5 in Fig. 7) In the imaging optical system 10C of the third embodiment, the structural data of each lens is shown in Tables 7 and 8. [Table 7]

Lens surface curvature radius Axis spacing (mm) Refractive index Abbe number (mm) WMT rl ♦ OO 0.600 1.8467 23.82 r2 6.996 1.267 γ3 OO 5.271 1.9229 16.83 γ4 OO 0.200 r5 * 6.217 1.804 1.7583 50.91 r6 -19.687 0.32 3.26 4.12 γ7* -11.559 0-600 1.4875 70.44 γ8 3.268 4· 40 ]·46 0.60 r9 (aperture) OO 0.000 r10 4,612 0.600 1.8467 23.82 γΙΙ 8,772 3· 62 1,81 1.20 γ12* 3.315 1.661 1.7554 51·42 Π3 -6.152 0.600 1.8241 24.09 Γ 3 3 3 3 3 3 3 3 3 3 3 3 3 200807018 [Table 8] Lens surface conic coefficient aspheric coefficient A Β CD rl 0 2.694E-04 -1.673Ε-05 6·003Ε-07 -9, 349Ε-09 r5 0 -S.982E-04 -1.6Ι6Ε-06 -4.825Ε-07 5.267Ε-09 r7 0 3·624Ε - 03 -3.716Ε-04 3.395Ε-05 -1.452Ε-06 Π2 0 -2-956Ε-03 5· 778Ε-05 -2.499Ε-05 Κ138Ε- 07 Π5 0 -2·2 卯Ε- 04 2.481Ε-04 - 3·292Ε-05 1.841Ε-06 Π6 0 2.700 Ε-03 2.879Ε-04 -5.662Ε-05 3.182Ε-06

[Embodiment 4] Fig. 8 is a cross-sectional view showing the configuration of the imaging optical system 10D according to the fourth embodiment, which is a longitudinal section of the optical axis (AX). The imaging optical system 10D of the fourth embodiment has a first lens (L1) and a cymbal formed by a negative meniscus lens recessed toward the image side in order from the object side on the optical path. (LP), a first lens group (Grl) composed of a second lens (L2) made of a biconvex positive lens and having positive optical power as a whole, and a third lens (L3) 1 made of a double concave negative lens The third lens group (Gr2) composed of a sheet, the aperture (ST), and the third lens group (Gr3) formed of one sheet of the fourth lens (L4) formed by the positive meniscus lens protruding toward the object side a fourth lens group (Gr4) formed of a fifth lens (L5) formed by a double convex positive lens and a sixth lens (L6) formed by a double concave negative lens, and having a positive optical power as a whole, and The fifth lens group (Gr5) composed of a seventh lens (L7) formed of a double convex positive lens is configured. Then, 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 group is substantially the same as that of the first embodiment, and the movement state of each lens group when the width is changed from the wide-angle end (W) to the telephoto end (T) (the arrows ml to m5 in Fig. 8 are shown). ) ' is also the same as the example-40-200807018 (38) 1. In the imaging optical system 10D of the fourth embodiment, the structural data of each lens is shown in Table 9 and Table 10.

-41 - 200807018 (39) [Table 9] Lens surface curvature radius Axis spacing (mm) Refractive index Abbe number (mm) WMT rl * oo 0.600 1.84666 23.82 r2 5.926 . Prepare r3 oo 1.305 4.829 1.9229 16.83 γ4 oo 0. 200 r5丰4.340 1.572 1.7572 51.11 • r6 -26.516 0.30 2.10 2.95 rT * -21.293 0.600 1.7492 51.75 r&amp; 2.840 2.95 1,15 0.30 r9 (aperture) oo 0.000 rlO 5· 133 0.400 1.8467 23.82 rll 14·103 6.06 3.36 1· 50 rI2* 4.676 2.358 1.7S45 51.57 • rV3 -5.726 0· 600 1.8467 23.82 r14 fi.936 0.70 3· 58 8.39 r!5 * 13.754 1.843 1.5305 55.72 r16* A 6.192 3.97 3.79 0.84 r17 00 0.500 1.5187 64. GO r18 oo 0.517 rl9 (image surface) oo -42- 200807018 (40) [Table 10] Lens surface aspheric coefficient conic coefficient ABCD Π 0 1.192E-03 _6,217E-05 2.250Ε-06 - 3.34SE-08 r5 0 -1.873 E-03 -2.668E-05 -2.410Ε-06 -3· 75 旺-08 r7 0 3.567E-03 Η·381Ε-04 -M30E-05 1.593E-05 Π2 0 -1.590E-03 5.122Ε-05 -7. 212卜0S 2.215E-07 Π5 0 - 9, dirty -04 -4J47E - 05 -2. 054E-06 -5.764E-07 r16 0 1.127E-03 -8.472Ε-07 -9.863E-06 -6.386E-08 [Example 5]

Fig. 9 is a cross-sectional view showing the configuration of the imaging optical system 10E according to the fifth embodiment, which is a longitudinal section of the optical axis (AX). The imaging optical system 10 E of the fourth embodiment has a first lens (L1) and a cymbal formed by a negative meniscus lens recessed toward the image side in order from the object side on the optical path. (LP), a first lens group (Grl) composed of a second lens (L2) made of a biconvex positive lens and having positive optical power as a whole, and a third lens (L3) 1 made of a double concave negative lens A third lens group (Gr2) composed of a sheet, a stop (ST), and a third lens group (Gr3) composed of a fourth lens (L4) formed by a positive meniscus lens protruding toward the object side (Gr3) a fourth lens group (Gr4) formed of a fifth lens (L5) formed by a double convex positive lens and a sixth lens (L6) formed by a double concave negative lens and having a positive optical power as a whole, And a fifth lens group (Gr5) composed of a seventh lens (L7) formed of a double convex positive lens. Then, on the image side of the fifth lens group (Gr5), an imaging element (SR) is disposed via a parallel plane plate (PL). The configuration of the lens group is substantially the same as that of the previous embodiment i, and the movement state of each lens group when zooming from the wide-angle end (W) to the telephoto end (T) (arrows ηι 1 to m 5 in Fig. 9) Also shown is the same as in the first embodiment. -43-200807018 (41) In the imaging optical system 10E of the fifth embodiment, the structural data of each lens is shown in Tables 1 and 12. [Table 11] Lens surface curvature radius Axis spacing (mm) Refractive index Abbe number (mm) WMT r1 * oo * η 7.222 0.600 1,8467 23.82 L368 r3 CO 5.634 1.9229 16.83 r4 oo 0.200 • r5 this 7.772 1.891 1.7859 46 · 78 r6 -19.736 0.30 3· 51 5.10 r7 * -15.464 0.600 1.4875 70.44 r8 3.845 5· 40 2.19 0.60 r9 (aperture) oo 0.000 rlO 4.595 0.600 1.9229 16.83 rll 7· 995 2.66 0.30 • r!2* 3.652 1.650 K7765 48.08 - Π3 -2.884 0.600 1.7560 25.13 r14 2· 883 1.47 3· 15 5,35 r15 this 8.661 2.007 1.5305 55,72 r16 * -6.134 2.12 1.90 0.60 r17 oo 0.500 1.5187 64.00 r18 oo 0,517 rl9 (image surface) oo -44 - 200807018 (42) [Table 12] Lens surface aspheric coefficient aspheric coefficient ABCD Π 0 1. 602E-05 -7.964E-06 2.6.83E-07 -2.S77E-09 r5 0 -3.142E-04 -4.955E- 07 -1.581E-07 1.108E-09 r7 0 2.303E-03 -L 990E - 04 1.879E-05 -9. 596E - 07 Π2 0 -3.270E-03 2·279E-04 -9.133E-05 8.26TE -06 r!5 0 -U005E-03 2.945E-04 -2.807E-05 1.456E-06 r 16 0 2.437E-03 1.495E-04 -2.900E-05 L 829E-06

The spherical aberration, astigmatism, and distortion aberration of the imaging optical systems 10B to 10E of the second to fifth embodiments based on the above-described lens arrangement and configuration are from the left side of FIGS. 11 to 14. In order. These imaging optical systems 10B to 10E are also substantially suppressed in terms of spherical aberration, astigmatism, and distortion at any of the wide-angle end (W), the intermediate point (M), and the telephoto end (T). Excellent optical properties. Further, the focal lengths (units mm) and F 时 at the wide-angle end (W), the intermediate point (M), and the telephoto end (T) of the zigzag optical systems 10B to 10E of the second to fifth embodiments are shown in Table 1, respectively. 3 and Table 1 4. As is apparent from these tables, a bright optical system can be realized in the same manner as in the first embodiment. [Table 13] Focal length f (mm) W Μ 实施 Example 1 4. 30 7' 70 11. 83 Example 2 4. 30 7. 74 11· 83 Example 3 3. 80 7. 60 10.64 Example 4 3 60 7. 20 13. 50 Example 5 3. 60 6. 48 9. 90 -45- 200807018 % (43) [Table 14] Confirm W Μ 实 Real! 11 4. 00 4. 54 5. 83 Example 2 4. 00 4. 47 5. 62 Example 3 4. 00 4. 47 5. 25 Example 4 4, 00 4, 66 6, 66 Love 5 4 , 00 4. 34 5. 08

In addition, the conditional expressions (1) to (6) above are shown in Table 15 when the imaging optical systems 10B to 10E described in the second to fifth embodiments are applied.

[Table 15] Example 1 Example 2 Example 3 Implementation of handle 4 Example 5 Conditional formula (1) 34. 87 31, 64 20. 26 41. 46 m ίο Conditional formula (2) 0. 74 0. 72 0. 61 0. 53 0. 52 Conditional formula (3) 1. 61 1. 58 1· 49 1·75 1. 59 Conditional formula (4) 57. 79 61· 24 70. 44 51. 70 59. 70 Conditional formula (5) 1. 92 2. 14 1. 92 1. 92 1. 92 Conditional formula (6) 1. 85 2. 14 1. 85 1. 85 1. 92 Zoom ratio 2. 75 2. 75 2. 80 3. 75 2. 75 Then, With respect to the conditional expression (2), the results of the above-described Examples 1 to 5 and the examples described in the above-mentioned Patent Documents 1 to 3 are shown in Table 16. In Table 1, the telephoto ratio is defined as [full length] / [focal length at the wide-angle end]. The smaller the telescope ratio, the more elaborate the camera optics. The imaging optical systems of Patent Documents 1 to 3 are outside the range of the conditional expression (2), and it is known that the telephoto ratio is large. That is, if the conditional expression (2) cannot be satisfied, the optical system is larger. -46- 200807018 (44) [Table 16] Conditional Formula/Approximate Range = 0.45 to 0.9 Telemetry Ratio Example 1 0. 74 6· 3 Example 2 0·72 6. 1 Example 3 0·61 7.2 Example 4 0. 53 8· 1 Example 5 0. 52 r 7· 8 Example 3 of Patent Document 1 0, 40 10. 1 Example 1 of Patent Document 2 0. 26 13. 8 实施 Example of Patent Document 2 6 0· 19 16. 1 Example 7 of Patent Document 2 0. 14 19. 9 Example 8 of Patent Document 2 0. 13 21, 2 Example 4 of Document 3 0·40 9. 8

As described above, the imaging optical systems i〇A to 1E of the above-described first to fifth embodiments are in the five-group variable magnification configuration in which the positive and negative positive and positive are sequentially from the object side. 1) ~ (6), so in addition to the full length is more compact, but also has excellent optical performance. Further, in the above specific embodiment, the invention mainly comprises the following constitution. An imaging optical system according to one aspect of the present invention is an imaging optical system which is formed by a plurality of lens groups and which can be multiplied by changing a lens group interval, and is characterized in that: a lens group having positive optical power, fixed at magnification, and including a reflecting member that bends an optical axis into a slightly right angle; and a second lens group having negative optical power in the optical axis direction Moving; and the third lens group 'having positive power; and the fourth lens group having positive optical power 'movable in the optical axis direction; and the fifth lens group having positive optical power' It can be moved in the direction of -47-200807018 (45) optical axis; it satisfies the following conditional formulas (1) and (2). 15&lt; (TL*ft)/( | dl2t-dl2w | *fw)&lt; 45 · · · (1) 〇.45&lt; (β 5t*fw)/(/3 5w*ft)&lt; 0.9 --- (2)

Wherein 'fw: the focal length of the entire imaging optical system at the wide-angle end ft: the focal length dl2w of the entire imaging optical system at the telephoto end: the wide-angle end from the most image-facing side of the lens in the first lens group, to the second lens group The distance dl2t on the optical axis from the most object side surface of the lens: from the most image side surface of the lens in the first lens group at the telephoto end, to the lens in the second lens group The distance TL on the optical axis from the surface on the object side: the distance from the most object side of the imaging optical system to the image plane, the distance yS5w on the optical axis: the wide-angle end when the subject distance is infinity Imaging magnification of the fifth lens group / 3 5t: The imaging magnification of the fifth lens group at the telephoto end when the subject distance is infinity is based on this configuration, and the imaging optical system as the variator lens system is from the object side. It consists of five lens groups that are "positive and positive". As will be described in detail later, the "magnification of positive and negative" five-group variator lens system is larger than the four-group form of "positive and negative", even in order to improve the overall length of the lens group. The aberration variation caused by the 'variation of power' can still be well suppressed. Therefore, it is advantageous in miniaturizing the entire length of the imaging optical system. -48 - 200807018 (46) By satisfying conditional expression (1) and conditional expression (2), it is possible to maintain a variable magnification ratio of each lens group constituting the variator lens system. The entire domain maintains good performance while achieving miniaturization.

In the conditional expression (1), when the lens position state is changed from the wide-angle end state to the telephoto end state, the second lens group can be satisfactorily corrected by satisfying the conditional expression (1) by satisfying the conditional expression (1). The aberration of the group changes. When the upper limit of the conditional expression (1) is exceeded, the moving distance of the second lens group is too small, and the tendency to reduce the magnification of the second lens group becomes remarkable. In the five-group zoom configuration of "positive and negative positive", since the second lens group is the only negative lens group, when the moving distance of the second lens group is small, the magnification load of the other lens groups is increased. Therefore, the moving distance between the fourth lens group and the fifth lens group belonging to the moving lens group is increased, and it is difficult to make the full length fine. On the other hand, if the lower limit of the conditional expression (1) is exceeded, the second Since the moving distance of the lens group is increased, the tendency of the total length of the imaging optical system 10 to become large becomes remarkable. In addition, the variation of the aberration caused by the magnification change becomes large. The difficulty in correcting the aberration variation by the lens of the other lens group increases. Therefore, it is difficult to obtain good optical performance across the entire zooming field. Conditional formula (2) is within the range specified by conditional formula (1), so that it can be well spanned across the entire zooming field. The optical condition is specified by @condition. In the five-group variable magnification configuration of "positive and negative positive" proposed so far, the ratio of the magnification ratio shared by the fourth lens group and the fifth lens group is not optimized. Therefore, when the power of each lens group is increased and the power of each lens group is increased, the aberration variation on the fourth lens group is increased, and the correction cannot be sufficiently performed, so that the full length is not refined and the intended purpose cannot be achieved. Question -49- 200807018 (47) Question.

In the present invention, the variable magnification of the fifth lens group is actively increased in the five-group variable magnification configuration of "positive and negative positive", thereby suppressing the fourth generation of the entire length of the miniaturization. The increase in the aberration variation of the lens group makes it possible to correct the aberration variation at the time of magnification change, and at the same time, it is possible to simultaneously achieve full-length miniaturization and high optical performance. When the upper limit of the conditional expression (2) is exceeded, the amount of magnification of the fifth lens group is increased. Therefore, the tendency of the aberration variation on the fifth lens group to become large becomes remarkable. Further, at the time of zooming, the incident angle of the off-axis beam to the image plane changes, and the reduction of the peripheral light is remarkable. On the other hand, when the lower limit of the conditional expression (2) is exceeded, the amount of magnification of the fifth lens group is reduced. Therefore, it is difficult to sufficiently correct the variation of the aberration when the fourth lens group is zoomed. In the more precise viewpoint of the imaging optical system 1 ,, the relationship of the conditional expression (1) above is preferable to satisfy the conditional expression of the following (1)'. 20&lt;(TL*ft)/( | dl2t-dl2w | *fw)&lt; 40 · · · (1), in particular, it is more desirable to satisfy the conditional expression of (1) below. 25&lt; (TL*ft)/ (1 dl2t-dl2w | *fw) &lt; 40 · · · (1) In the same way, the relationship of the above conditional expression (2) is satisfied by the viewpoint of the more precise imaging optical system. The conditional formula of ' is preferred. 0.5&lt; (/3 5t*fw)/(yS 5w*ft)&lt; 0.8 · · · (2)' In particular, it is more desirable to satisfy the conditional expression of (2) below. 0.6&lt; (β 5t *fw)/(/3 5w*ft)&lt;0.75 · · · (2)" -50- 200807018 (48) In the above composition, the second lens group is formed by one negative ^ 13⁄4, The lens system has at least one aspherical surface, and it is preferable to satisfy the following conditional expressions (3) and (4). 1.45 &lt; Nd2 &lt; 1.8 · · · (4 5 &lt; v 2 &lt; 15 · · · · (4) where N d 2 : the refractive index of the negative lens on the d line v 2 : the negative lens Number of shells

Reducing the number of lenses of each lens group as much as possible is a direct shortening of the total length of the optical system. By forming the second lens group in one piece, the imaging optical system can be made compact. It also reduces the burden of driving the drive unit of the table 2 group at the time of zooming. By the way, in the five-group zoom configuration of "positive and positive positive", in order to reduce the magnification load of the second lens group, even when the second lens group is constituted by one negative lens, the height can be maintained high. Optical performance. If the upper limit of the conditional expression (3) is exceeded, it is difficult to keep the Petzval and the appropriate lanthanum. By the way, in the imaging optical system according to the present invention, the second lens group is the only group having a negative power. Therefore, if the upper limit of the conditional expression (3) is exceeded, the negative lens of the second lens group is negative. It will become smaller, and it is difficult to fully correct the positive Petz Law of other lens groups. Therefore, the image curvature is remarkable, and good optical performance cannot be obtained. Further, when the upper limit of the conditional expression (4) is exceeded, it is difficult to correct the chromatic aberration. On the other hand, if the lower limit of the conditional expressions (3) and (4) is exceeded, the molded lens material which is excellent in general efficiencies does not exist under the current conditions, so that it is difficult to manufacture. With regard to the conditional expressions (3) and (4) above, the viewpoint of improving the suppression of field curvature and improving the correction performance of chromatic aberration is full-51 - 200807018 (49) (3) ', (4)' is preferred. 1.5 &lt;Nd2&lt; 1.75 · · · (3)9 50&lt;〉2&lt;60 · · · (4)9 In the above composition, the pre-reflective part is made of rib It is preferable that the enthalpy is satisfied by the following conditional expression (5).

Nd &gt; 1.85 .--(5) where N d : the refractive index of the 稜鏡 on the d line

By using 稜鏡' having a refractive index satisfying the range of the conditional expression (5), it is possible to improve the expectation of the compaction of the imaging optical system by the enamel. If the refractive index of ruthenium is lower than the range of conditional expression (5), not only is the lack of expectation of precision, especially in the shortest focal length state, the inclination of the chief ray in the crucible becomes large, so it will approximate The reflection condition makes the light amount loss large, which is not preferable. In addition, from the viewpoint of improving the precision of the imaging optical system 10, it is more preferable to satisfy the Nd of the conditional expression (5)' below.

Nd &gt; 1.9 · · · (5)5 In the above configuration, the third lens group is composed of one positive lens, and the conditional expression (6) below is preferable. N3d&gt; 1.7 --- (6) where N3 d : the refractive index on the d line of the positive lens is obtained by constituting the third lens group in one piece, whereby the imaging optical system can be made fine. When the range of the conditional expression (6) is less than the range of the conditional expression (6), the curvature of the positive lens constituting the third lens group is increased, so that the aberration variation at the time of magnification is increased. Therefore, it is difficult to achieve good performance across the entire zoom field. In addition, from the viewpoint of further reducing the fluctuation of the preceding aberration and improving the optical performance, it is more preferable to satisfy N 3 d of the conditional expression (6)' below. N3d&gt; 1.75 · (6) In the above description, the optical component is made of a resin material, and the optical component is a resin obtained by dispersing inorganic particles having a maximum length of 3 Å or less in a resin material. The optical component formed by the material is more reasonable

On the other hand, if fine particles are mixed in a transparent resin material, light scattering occurs and the transmittance is lowered. Therefore, it is difficult to use it as an optical material. However, by making the size of the microparticles smaller than the wavelength of the penetrating beam, the scattering does not substantially occur. Although the resin material lowers the refractive index as the temperature rises, the inorganic fine particles increase in refractive index as the temperature rises. Thus, the refractive index change hardly changes by utilizing their temperature dependence to cancel each other out. Specifically, by dispersing inorganic particles having a maximum length of 30 nm or less in a resin material as a base material, a resin material having an extremely low temperature dependence of the refractive index can be obtained. For example, by dispersing fine particles of cerium oxide (Nb20 5) in the acrylate, the change in refractive index due to temperature change can be made small. Therefore, as the optical member (the lens or the prism constituting each lens group) used in the present invention, the resin material in which the inorganic particles are dispersed is used, and the entire system of the imaging optical system according to the present invention can be used in the environment. The change in the position of the image point caused by the temperature change is suppressed to be small. In the above description, it is preferable that the fifth lens group is moved while focusing. -53- 200807018 (51) Since the 5th lens group has positive power, it can be focused from infinity to close objects by sending it to the object side. At this time, under the same subject distance, the amount of delivery is small at the wide-angle end. At the telephoto end, the amount of delivery is large. In the five-group variable magnification configuration of "positive and negative positive" according to the present invention, when the magnification is changed from the wide-angle end to the telephoto end, since the interval between the fourth lens group and the fifth lens group is monotonously increased, it is at the telephoto end. Also, focus can be performed without increasing the overall length.

An imaging lens device according to another aspect of the present invention includes the imaging optical system described above and an imaging element that converts an optical image into an electrical signal; and the pre-recording optical system is assembled so that the imaging element can be pre-recorded An optical image of the subject is formed on the light receiving surface. According to this configuration, for example, an image pickup lens device that can be mounted on a compact digital camera or a mobile information terminal and has excellent optical performance can be provided. According to still another aspect of the present invention, a digital device includes: an image pickup lens device; and a control unit configured to form at least one of a still image and an animation image of a subject on the front image pickup lens device Photography was carried out. According to this configuration, it is possible to realize a compact and high-definition digital camera such as a compact digital camera or a mobile information terminal. According to the present invention having the above configuration, when the power of each lens group is increased in order to improve the overall length, it is also possible to adopt a positive or negative correction capable of suppressing the aberration variation caused by the magnification change. The five groups of positive change constitutes. Further, it is configured such that the ratio of the magnification ratio of each lens group is taken to be appropriate. Therefore, it is possible to provide an optical lens that achieves excellent optical performance and has excellent optical performance across the entire zooming field. -54 - (52) 200807018 Series, an imaging lens device, and a digital device equipped with the imaging lens device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the configuration of an imaging optical system according to an embodiment of the present invention.

Fig. 2 is a view showing the external configuration of a digital camera according to an embodiment of the digital device according to the present invention, wherein (a) is a front view of a coefficient camera, (b) is a rear view, and (c) is a top view. [Fig. 3] A schematic diagram of the function of the electrical function of the digital camera. Fig. 4 is a cross-sectional view showing the configuration of the imaging optical system of the first embodiment, which is a longitudinal section of the optical axis. Fig. 5 is a view showing a configuration of an imaging optical system of the first embodiment, in which a 稜鏡 portion is developed into a straight line optical path diagram. Fig. 6 is a view showing the configuration of the imaging optical system of the second embodiment, in which a 稜鏡 portion is developed into a straight line optical path diagram. Fig. 7 is a view showing the configuration of the imaging optical system of the third embodiment, in which a 稜鏡 portion is developed into a straight line optical path diagram. Fig. 8 is a view showing a configuration of an imaging optical system of a fourth embodiment. A straight line optical path diagram in which a 稜鏡 portion is developed into a straight line. Fig. 9 is a view showing a configuration of an imaging optical system of a fifth embodiment. A straight line optical path diagram in which a 稜鏡 portion is developed into a straight line. Fig. 1 is a diagram showing aberrations of spherical aberration, astigmatism, and distortion of the imaging optical system of the first embodiment. -55-200807018 (53) Fig. u is a diagram showing aberrations of spherical aberration, astigmatism, and distortion of the imaging optical system of the second embodiment. Fig. 1 is an aberration diagram of spherical aberration, astigmatism, and distortion of the imaging optical system of the third embodiment. [Fig. 13] Aberration diagram of spherical aberration, non-point image difference, and distortion of the imaging optical system of the fourth embodiment. Fig. 14 is a diagram showing aberrations of spherical aberration, non-point image winning, and distortion of the imaging optical system of the fifth embodiment. [Main component symbol description]

1 〇: Camera optical system ' 1 1 ·• Negative meniscus lens, 1 2 ·•Doubly convex positive lens, 13 :稜鏡, 1 3 a : Incidence surface, 1 3 b ··Outflow surface, 13 C :Reflection Face, 14: double concave negative lens, 15: positive meniscus lens, 16: bonding lens, 161: double convex positive lens, 162: double concave negative lens, 17: double convex positive lens, 18: low pass filter , 1 9 : camera unit, 01: aperture, 20: digital camera, 21: main switch, 22: mode switch, 23: shutter button, 24: flash, 25: viewfinder, 26: various operation buttons, 27: Zoom bar, 2 8 : display unit, 2 9 · image pickup lens device, 30 · image pickup unit, 3 1 : image generation unit, 32: image data buffer, 33: image processing unit, 34: drive unit, 35: control unit, 36: memory unit, 37: dielectric surface, Grl: first lens group ' Gr2 : second lens group, Gr3 : third lens group, Gr4 : fourth lens group, Gr5 : fifth lens group, L1 to L7: 1st lens to 7th lens, PR: 稜鏡, PL: parallel plane plate, AX: optical axis, ST: aperture, SR: imaging element. -56-

Claims (1)

200807018 (1) X. Patent application scope 1. An imaging optical system is an imaging optical system that is formed by a complex lens group and can be multiplied by changing the lens group interval, and is characterized by 'from the object side. The sequence includes: a second lens group having a positive optical power 'fixed at the time of magnification, and a reflection member that bends the optical axis to a slightly right angle; and a second lens group having a negative optical power' In the direction of the optical axis Moving; and a third lens group having positive optical power; and a fourth lens group having positive optical power movable in the optical axis direction; and a fifth lens group having positive optical power, Moving in the direction of the optical axis; and satisfying the following conditional expressions (1), (2): 1 5 &lt; (TL * ft) / ( | d 1 21-d 1 2 w 丨 * fw) &lt; 4 5 · (1) 0.45&lt;(β 5t*fw)/(/3 5w*ft)&lt; 0.9 · · · (2) where fw: the focal length of the entire imaging optical system at the wide-angle end ft: the entire imaging optical system at the telephoto end The focal length d 1 2 w is the 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 TL 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: imaging optical system The surface of the most object side is calculated as -57-200807018 (2), the distance on the optical axis / 3 5w: the fifth end of the wide-angle end when the subject distance is infinity Groups in imaging magnification / 3 5t ·· subject distance, the imaging magnification of the fifth lens group at infinity at the telephoto end. 2. The imaging optical system according to the first aspect of the patent application, wherein the conditional expressions (1)' and (2)' below are satisfied: 2 0&lt; (TL*ft)/( | dl2t-dl2w | *fw)&lt; 40 · · · (1)5 0.5&lt; (β 5t*fw)/(^ 5w*ft)&lt; 0.8 · · · (2)'. 3. The imaging optical system according to the first aspect of the patent application, wherein the following conditional formula (1) ", (2)" is satisfied: 25 &lt; (TL*ft) / ( | dl2t-dl2w | *fw &lt; 40 · · · (1)" 〇^6&lt;(β 5t*fw)/(/3 5w*ft)&lt;0.75 · · · (2)". 4. The imaging optical system according to the second aspect of the invention, wherein the second lens group is formed by one negative lens; and the negative lens has at least one surface aspherical surface, and satisfies the following conditional expression (3) ), (4): 1.45 &lt; Nd2 &lt;1.8 ---(3) 45 &lt; v 2&lt; IS ---(4) where Nd2: the refractive index of the negative lens on the d line v 2 : Abbe number of the negative lens. 5. The imaging optical system according to claim 3, wherein the second lens group is formed by one negative lens; and the negative lens has at least one surface aspherical surface, and satisfies the following condition -58- 200807018 (3) Formula (3)', (4)': 1.5 &lt; Nd2 &lt; 1.75 · · · (3), 5 0&lt;y2&lt;60 · · .(4),. 6. The imaging optical system according to claim 1, wherein the second lens group is formed by one negative lens; and the negative lens has at least one surface aspherical surface and satisfies the following conditional expression (3) ), (4): 1.45 &lt; Nd2 &lt;1.8 · · · (3) 4 5 &lt; 2 &lt; 7 5 · · *(4). 7. The imaging optical system according to claim 1, wherein the second lens group is formed by one negative lens; and the negative lens has at least one surface aspherical surface and satisfies the conditional expression below (3) ) ', (4)' : 1 .5 &lt; Nd2 &lt; 1.75 · · · (3), 50 &lt; v 2 &lt; 60 · · · (4),. 8. The imaging optical system according to item 6 of the patent application scope, wherein the pre-reflecting member is made of ruthenium, and the lanthanum system satisfies the following conditional expression (5): Nd &gt; 1.85 --- (5) , Nd : The refractive index of the 稜鏡 on the d line. 9. The imaging optical system according to claim 7, wherein the front reflective member is formed of a prism, and the 稜鏡 system satisfies the following conditional expression (5): Nd &gt; 1.9 · · · (5), . -59- (4) 200807018 l 〇 · As in the patent image range, the image-based optical system contained in the gS of the first item, in which the pre-reflective part is made of 稜鏡, the 稜鏡 system satisfies the following conditional expression (5): Nd &gt; 1.85 ..-(5)° 11. As in the first part of the patent application, in the first part of the film, the first part of the camera is 'the front part of the reflection part is made of 稜鏡 '' )' : Nd&gt; 1.9 · · · (5)’. 1 2 . The imaging optical system described in the first paragraph of the patent application, wherein the third lens group is formed by one positive lens and satisfies the following conditional expression (6): N3d&gt; 1.7 ---( 6) where N3 d : the refractive index of the positive lens on the d line. 1 3 . The imaging optical system described in the first aspect of the patent application, wherein the third lens group is formed by one positive lens and satisfies the following conditional expression (6)': N3 d &gt; 1.75 · · (6)'. The imaging optical system according to the first aspect of the invention, wherein the third lens group is formed by one positive lens and satisfies the following conditional expression (6): N3d &gt; 1.7 · · · ( 6). The imaging optical system according to the first aspect of the invention, wherein the optical component formed by the resin material is contained; the optical component of the pre-recorded optical component is dispersed in the resin material for a maximum length of -60 - 200807018 (5) An optical @piece formed from a resin material made of inorganic particles of 30 nm or less. 16. The imaging optical system according to the first aspect of the patent application, wherein the fifth lens group is moved while focusing. An imaging lens device comprising: an imaging optical system described in the first application of the patent application; and an imaging device that converts an optical image into an electrical signal; The pre-recording optical system is assembled so that an optical image of a subject can be formed on the light-receiving surface of the image sensor. The image pickup lens device according to claim 17, wherein the reflection member included in the pre-recording optical system is made of 稜鏡, and the 稜鏡 system satisfies the following conditional expression (5), and The fifth lens group is moved while focusing; Nd &gt; 1.85 · · (5). A digital apparatus comprising: an imaging lens device according to claim 17; and a control unit ??? at least one of a still image and an animated image in which a subject is formed on a front imaging lens device; The photography of the person was carried out.