[Illegible]
`
`Certification Request
`
`Jan. 23, 2020
`
`To: JPO Commissioner
`
`1. Case Indication
`
`2. Requestor
`
`JP 2009-202205
`
`Postal Code
`Address or Residence
`
`101-0063
`2-105 Kanda Awaji-chō, Chiyoda-ku, Tokyo
`Waterras Annex 1205
`
`Name or Title
`
`Tarō Yaguchi
`
`3. Name of Document to Be Certified
`
`Unexamined Patent Application Publication (JP 2011-55246 A)
`
`Please certify that this is identical to what is given as the name of the document to be certified.
`
`I certify that this is identical to the name of the document to be certified.
`
`Feb. 4, 2020
`
`JPO Commissioner:
`
`[Seal of JPO
`Commissioner]
`
`[Akira Matsunaga]
`
`2020 Application Certificate No. 600023
`
`APPL-1010 / Page 1 of 30
`Apple v. Corephotonics
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`JP 2011-55246 A 2011.3.17
`
`(19) Japan Patent Office (JP)
`
`(12) Unexamined Patent Application Publication (A)
`(11) Patent Application Publication No.
`
`(2006.01)
`(2006.01)
`
`FI
`H04N
`G03B
`
`JP 2011-55246
`(P2011-55246A)
`(43) Publication Date: Mar. 17, Heisei 23 (2011.3.17)
`Theme Code (Ref.)
`
`5/225 Z
`19/07
`
`2H054
`5C122
`
`(11 Pages Total)
`
`(51) Int. Cl.
`H04N
`G03B
`
`5/225
`19/07
`
`
`
`(21) Filing No.
`
`(22) Filing Date
`
`No. of Claims: 5 OL
`Examination Request: Not Made
`JP 2009-202205 (P2009-
`(71) Applicant
`000005821
`202205)
`Panasonic Corp.
`Sep. 2, Heisei 21 (2009.9.2)
`1006 Kadoma, Kadoma-shi, Osaka
`100109667
`Hiroki Naitō, Patent Attorney
`100109151
`Daisukue Nagano, Patent Attorney
`100120156
`Kentarō Fujii, Patent Attorney
`Hitomaro Tōgō
`c/o Panasonic Mobile
`Communications Co. Ltd.
`600 Saedo-chō, Tsuzuki-ku,
`Yokohama-shi, Kanagawa-ken
`2H054 BB06 BB07
`5C122 DA09 EA54 FA18 FB03
`FB11 FC01 FE03 FH07
`FH18 FK12
`
`(74) Agent
`
`(74) Agent
`
`(74) Agent
`
`(72) Inventor
`
`F Terms (Ref.)
`
`(54) [Title] Telephoto Imaging Device
`
`(57) [Abstract]
`[Problem] A conventional imaging device with a telephoto
`zoom function using an optical zoom lens needs, for
`example, a motor for moving a lens system and is therefore
`difficult to apply in a thin mobile terminal device.
`Moreover, a conventional telephoto zoom function that
`switches between images of an imaging device having a
`plurality of focal lengths according to a designated
`magnification has a problem where an enlarged image at a
`close distance is blurred.
`[Solution] By having an imaging module having a wide-
`angle lens, an imaging module having a telephoto lens, and
`a measurement means for measuring a distance to a
`subject and compositing a wide-angle image and a
`telephoto image according to the distance of the subject, a
`mobile terminal device that is thin and has a telephoto
`imaging device with a telephoto magnification of a wide
`dynamic range can be realized.
`[Selected FIG.] FIG. 1
`
`
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`APPL-1010 / Page 2 of 30
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`(2)
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`JP 2001-55246 A 2011.3.17
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`[Claims]
`[Claim 1]
`An imaging device or a mobile terminal device including the imaging device, comprising: a first imaging
`module having a wide-angle lens system, a first imaging element, and an autofocusing means; a second
`imaging module that has an optical axis parallel to the first imaging module and is made of a telephoto lens
`system focused in the distance and a second imaging element; an image control means; a display device; and a
`keying means; wherein
`the image control means, when a setting magnification X set by a user via the keying means is less than a
`predetermined magnification A, cuts out an image corresponding to the setting magnification X from a
`photographic image of the first imaging element and displays this enlarged on the display device;
`further comprised is a photography-distance estimation means for estimating a photography distance Y
`between a photography subject and the mobile terminal device;
`the image control means, when the photography distance Y is greater than a predetermined distance B and
`the setting magnification X is the predetermined magnification A or greater, generates a composite image
`where a photographic image of the second imaging element is pasted in a substantially central portion of the
`photographic image of the first imaging element and composited therewith and afterward cuts out an image
`corresponding to the setting magnification X from the composite image and displays this enlarged on the
`display device; and
`when the photography distance Y is the predetermined distance B or less, an image corresponding to the
`setting magnification X is cut out from the photographic image of the first imaging element and displayed
`enlarged on the display device.
`[Claim 2]
`The imaging device or the mobile terminal device including the imaging device of claim 1, wherein the
`photography distance Y between the photography subject and the mobile terminal device is estimated from
`an output signal of the autofocusing means or a control signal controlling the autofocusing means.
`[Claim 3]
`The imaging device or the mobile terminal device including the imaging device of claim 1, wherein a
`relationship between a pixel density N1 of the first imaging element, a pixel density N2 of the second imaging
`element, and a telephoto magnification C of the second imaging element relative to the first imaging element
`satisfies the following condition:
`N1 < N2 ∙ C2 [Claim 4]
`The imaging device or the mobile terminal device including the imaging device of claim 3, wherein a size of
`the second imaging element is smaller than the first imaging element.
`[Claim 5]
`The imaging device or the mobile terminal device including the imaging device of claim 1, further comprising:
`one or more mirrors or prisms that change an optical path of the telephoto lens system of the second image
`module by 90 degrees.
`
`[Detailed Description of Invention]
`[Technical Field]
`[0001]
`The present invention relates to a mobile phone or mobile terminal device that includes an imaging device.
`[Background Art]
`[0002]
`
`Digital cameras and imaging devices (cameras) of mobile terminal devices such as mobile phones are
`becoming more highly functional, and there is also a rising demand for a telephoto zoom function.
`Conventional imaging devices with telephoto zooming have an optical zoom lens having a multi-group lens
`system made of a plurality of lenses and an imaging element (CCD) and can change a magnification by
`mechanically moving a relative position of the lens system using a motor or the like. Because a multi-group
`lens has a large size in an optical-axis direction, among methods proposed for shortening its length include
`utilizing a prism (for example, patent literature 1).
`Furthermore, by switching between or compositing images of a plurality of optical systems and a plurality of
`imaging elements joined to these optical systems, a wide dynamic range of enlargement magnification from
`wide-angle to telephoto can be realized (for example, patent literatures 2, 3).
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`JP 2001-55246 A 2011.3.17
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`Furthermore, because an auto-adjusting optical zoom lens needs motor driving and the like, it is
`difficult to reduce in size. As such, there is a method of realizing a small camera with telephoto zooming by
`combining a camera having a plurality of focal lengths and electronic (digital) zooming (for example, patent
`literature 4).
`[Citation List]
`[Patent Literature]
`[0003]
`[Patent Literature 1] JP 3570253 B2
`[Patent Literature 2] JP 4068869 B2
`[Patent Literature 3] JP 2005-101874 A
`[Patent Literature 4] JP H2-179078 A
`[Summary of Invention]
`[Problem to be Solved by Invention]
`[0004]
`
`To realize a telephoto function, a lens with a long focal length or a telephoto lens system is necessary,
`and a distance of a certain extent is necessary between a lens on an outermost side and an imaging element.
`[0005]
`
`10
`
`Meanwhile, to realize a wide angle, a lens diameter relative to a distance between the imaging
`element and a lens in an endmost portion needs to be increased using a lens of a short focal length.
`[0006]
`
`20
`
`A conventional optical zoom lens is a structure that lines up a plurality of lens systems—two to four
`groups—vertically to realize the above telephoto and wide-angle by one optical system; a length of a camera
`in an optical-axis direction and a horizontal width of the camera are large, making size reduction difficult.
`Application is particularly difficult in mobile terminal devices, which require thinness.
`[0007]
`
`Patent literatures 2, 3, 4 above realize a zoom function by using a plurality of imaging modules made
`of a plurality of lenses with different focal lengths—that is, lenses of different fixed magnifications. Images of
`the imaging modules are switched between according to each magnification set by a user.
`[0008]
`
`For example, in a configuration of two modules of an imaging module with a wide-angle lens and an
`imaging module with a telephoto lens, when a subject is at a short distance, an image of the imaging module
`of the wide-angle lens, which has a short focal length, is switched to, and when the subject is at a long
`distance, an image of the imaging module with the telephoto lens is switched to. Small changes in
`magnification are realized by electronic zooming, which changes a cutout region from a photographic image.
`This renders a multi-group lens and motor necessary for optical zooming unnecessary.
`[0009]
`
`However, a zooming method with the two imaging modules of the fixed magnifications above has the
`following problems.
`[0010]
`
`Each imaging module needs a focus adjustment function for focusing the lens on a range of subjects,
`from a subject at a close distance to a subject at a long distance. While small in comparison to a lens
`movement amount necessary to change a magnification in optical zooming, focus adjustment needs to move
`the focus lens by a motor, an actuator, or the like, which becomes a factor in increasing a size of an optical
`lens system.
`[0011]
`
`Note that when there is no focus adjustment function, two or more imaging modules adjusted to
`focus on subjects at different distances need to be used. Images of many imaging modules need to be switched
`between in small increments according to the distance to the subject, making size reduction difficult.
`Moreover, an image becomes blurry when there is no imaging module that matches the distance to the
`subject.
`[0012]
`
`Telephoto imaging modules with a long focal length are often designed so an image quality improves
`when the subject is far as opposed to near. That is, a telephoto imaging module with a long focal length is less
`sharp at close distances compared to a wide-angle imaging module whose focal length is short.
`[0013]
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`JP 2001-55246 A 2011.3.17
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`10
`
`Therefore, when the user sets a high magnification, a switch is made from the wide-angle imaging
`module to the telephoto imaging module. However, at this time, if the subject is close, the image quality
`degrades due to the image being from the telephoto imaging module.
`[0014]
`
`In particular, making a magnification of the telephoto lens too large degrades the close-distance
`image even more. As such, the telephoto imaging module needs to have a small telephoto magnification so
`even if the subject is at a close distance, focus adjustment is performed so the image quality is not degraded.
`Because of this, a zoom function with a large telephoto magnification cannot be realized.
`[0015]
`
`Furthermore, increasing the magnification of the telephoto lens lengthens the telephoto imaging
`module and increases a movement amount of the focal length, thereby prohibiting size reduction. Therefore,
`the telephoto magnification cannot be increased.
`[0016]
`
`When the subject is at a close distance, a change in the distance from the subject causes a change in
`center positions of the image of the wide-angle imaging module and the image of the telephoto imaging
`module. As such, as described in patent literature 3 for example, center-position correction according to the
`distance is necessary.
`[Solution to Problem]
`[0017]
`
`20
`
`[0018]
`
`Next, means for solving the above problem is described.
`
`A mobile terminal device of the present invention is an imaging device, having: a first imaging
`module having a wide-angle lens system, a first imaging element, and an autofocusing means; a second
`imaging module that has an optical axis parallel to the first imaging module and is made of a telephoto lens
`system focused in the distance and a second imaging element; an image control means; a display device; and a
`keying means; wherein when a setting magnification X set by a user via the keying means is less than a
`predetermined magnification A, an image corresponding to the setting magnification X is cut out from a
`photographic image of the first imaging element and displayed enlarged on the display device; further had is
`a photography-distance estimation means for estimating a photography distance Y between a photography
`subject and the mobile terminal device; when the photography distance Y is greater than a predetermined
`distance B and the setting magnification X is greater than the predetermined magnification A, a composite
`image where a photographic image of the second imaging element is pasted in a substantially central portion
`of the photographic image of the first imaging element and composited therewith is generated, and afterward,
`an image corresponding to the setting magnification X is cut out from the composite image and displayed
`enlarged on the display device; and when the photography distance Y is the predetermined distance B or less,
`an image corresponding to the setting magnification X is cut out from the photographic image of the first
`imaging element and displayed enlarged on the display device.
`[0019]
`
`Furthermore, in the mobile terminal device of the present invention, the photography distance Y
`between the photography subject and the mobile terminal device is estimated from an output signal of the
`autofocusing means or a control signal controlling the autofocusing means.
`[Advantageous Effects of Invention]
`[0020]
`
`According to the present invention, an imaging device for a mobile terminal device that is thin and
`has a large telephoto magnification can be realized without the need for an optical zoom lens or a focus
`adjustment function of a telephoto lens.
`[Brief Description of Drawings]
`[0021]
`[FIG. 1] A block configuration view of a mobile terminal device of embodiment 1 of the present invention.
`[FIG. 2] A structural view of a first imaging module of embodiment 1 of the present invention.
`[FIG. 3] A structural view of a second imaging module of embodiment 1 of the present invention.
`[FIG. 4] A sectional view of an imaging device of the mobile terminal device of embodiment 1 of the present
`invention.
`[FIG. 5] A diagram illustrating an enlarged-image generation method of embodiment 1 of the present
`invention.
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`JP 2001-55246 A 2011.3.17
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`[FIG. 6] A diagram illustrating the enlarged-image generation method of embodiment 1 of the present
`invention.
`[FIG. 7] A diagram illustrating positional relationships between the imaging modules of embodiment 1 of the
`present invention and a subject.
`[Description of Embodiments]
`[0022]
`
`An embodiment of the present invention is described below using the drawings.
`(Embodiment 1)
`FIG. 1 is a block configuration view of a mobile terminal device of the present invention.
`
`10
`
`[0023]
`
`A first imaging module 1 is an imaging module for a wide-angle image and is made of a wide-angle
`lens system 7, a first imaging element 8 such as a CCD camera, and an autofocus adjustment (autofocusing)
`means 9.
`[0024]
`
`The wide-angle lens system 7 has a constant focal length—that is, it is a fixed-magnification lens
`system. Because it lacks a variable-power function—that is, a zoom function—it has fewer lenses compared
`to an optical zoom lens and is small. The autofocus adjustment means 9 enables photography of an image of a
`subject that is, for example, several tens of centimeters to several meters away. The autofocus adjustment
`means 9 has a structure of moving a focus lens in the wide-angle lens system in an optical-axis direction and
`performs focus adjustment of image formation onto the first imaging element 8 according to the distance to
`the subject. As a method of changing a distance between the focus lens and the first imaging element 8, for
`example, an actuator using a piezo element that changes a movement amount in response to an applied
`voltage can be utilized.
`[0025]
`
`FIG. 2 illustrates one example of a structure of the first imaging module, which includes a wide-angle
`lens. The distance between the focus lens (wide-angle lens) and the first imaging element 8 can be adjusted
`by changing a thickness of an actuator 13 fixed to the first imaging element.
`[0026]
`
`20
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`30
`
`A second imaging module 2 is an imaging module for a telephoto image and is made of a telephoto
`lens system 10 and a second imaging element 11 such as a CCD camera.
`[0027]
`
`40
`
`The telephoto lens system 10 is a fixed-magnification lens system with a higher magnification than
`the above wide-angle lens, an enlarging magnification thereof being constant, and has no zoom function.
`[0028]
`
`FIG. 3 is one example of the telephoto lens system and is constituted by two lenses 15 with different
`focal lengths. A size in the optical-axis direction is greater than the wide-angle lens system. However,
`compared to a conventional telephoto lens system made of a multi-group lens including a zoom function, it
`has a low lens count and is small.
`[0029]
`
`As in FIG. 3, by inserting a mirror 16 or a prism near a lens 15, an optical axis can be changed by 90
`degrees.
`[0030]
`
`Furthermore, because the telephoto imaging module 2 only photographs a subject at a far distance—
`for example, several tens of meters or more—there is no need to finely adjust a distance between the
`telephoto lens system and the second imaging element 11, rendering a focus adjustment function for image
`formation from the telephoto lens system onto the imaging element unnecessary. Therefore, an actuator for
`focus adjustment is unnecessary, which is suited for size reduction.
`[0031]
`
`50
`
`Image data from the first imaging module 1 and the second imaging module 2 are input to an image
`control means 4.
`[0032]
`
`A measurement means 3 is a means for measuring an imaging distance (defined as Y) between the
`mobile terminal device and the subject. It estimates the distance (Y) as follows from, for example, an actuator
`control voltage of the autofocus adjustment means 9 of the first imaging module 1.
`[0033]
`
`
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`APPL-1010 / Page 6 of 30
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`(6)
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`JP 2001-55246 A 2011.3.17
`
`An actuator control voltage after autofocusing is a signal related to the distance between the focus
`lens and the imaging element. Therefore, the distance between the focus lens and the imaging element can be
`estimated from this control voltage. Moreover, because there is a relationship of the distance to the subject
`being farther the closer the distance between the focus lens and the imaging element is, an approximate
`distance (Y) to the subject can be estimated from the actuator control voltage.
`[0034]
`
`The measurement information (Y) is input to the image control means 4. Note that as described
`below, the measurement information (Y) is utilized as determination material for image control and does not
`need to be an accurate distance.
`[0035]
`
`The above measurement means is a method of estimating the distance Y from the autofocus
`adjustment means, but, for example, a measurement means for measuring the distance to the subject using
`ultrasonic waves or infrared light may be used instead. However, in this situation, a component for
`measurement (such as an ultrasonic-wave generation means or a detection means) needs to be newly added.
`[0036]
`
`A user sets a setting magnification (defined as X) of the image of the subject to be photographed via a
`keying means 6, and this setting magnification X is input to the image control means 4.
`[0037]
`
`The image control means 4 performs image processing based on the image from the first imaging
`module 1, the image from the second imaging module 2, the measurement information (Y), and the setting
`magnification (X) and afterwards performs display on a display device 5.
`[0038]
`
`(1) and (2) in FIG. 4 illustrate sectional schematic views of when the first imaging module 1 and the
`second imaging module 2 are incorporated in a mobile terminal device 17. Optical axes of the first imaging
`module 1 and the second imaging module 2 are parallel, and these modules are disposed so a distance
`between the optical axes is as close as possible.
`[0039]
`
`As illustrated in FIG. 4, a size of an optical system of the first imaging module in the optical-axis
`direction and a size of an optical system of the second imaging module in a direction perpendicular to the
`optical axis are smaller compared to a conventional lens with an optical zoom function. As such, mounting in a
`mobile terminal device that is thinner than conventional devices is possible.
`[0040]
`
`The second imaging module in (1) in FIG. 4 has a structure that inserts the mirror or prism
`immediately before an endmost lens in the telephoto optical system to change an optical path by 90 degrees.
`This enables an optical axis of the camera to be set in a direction perpendicular to a thin housing surface of
`the mobile terminal device. Note that the mirror may be in any position as long as it is on the optical axis of
`the telephoto optical system.
`[0041]
`
`Meanwhile, the second imaging module in (2) in FIG. 4 does not have a mirror and can set an optical
`axis of the camera in a direction parallel to the thin housing surface of the mobile terminal device.
`[0042]
`
`Next, an image processing method in the image control means 4 is described in detail.
`
`[0043]
`
`[0044]
`
`(1) to (4) in FIG. 5 illustrate an enlarged-image generation method at each magnification.
`
`Note that FIG. 5 supposes that the imaging distance (Y) between the mobile terminal device and the
`subject is long, at several tens of meters or more. That is, a predetermined distance B is defined as a length of
`several tens of meters, and a situation is supposed where the imaging distance Y is greater than B.
`[0045]
`
`20 indicates the wide-angle image from the first imaging module, and 21 indicates the telephoto
`image from the second imaging module.
`[0046]
`
`(1) in FIG. 5 is an image at a minimum magnification X = 1. Displayed is an entirety of the image from
`the first imaging module 1 after autofocus adjustment.
`[0047]
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`JP 2001-55246 A 2011.3.17
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`(2) in FIG. 5 is an enlarged image when the setting magnification X is about 1.5. So-called digital
`zooming is performed by cutting out an image of a predetermined size centered around an image center of
`the first imaging module and displaying this enlarged. When the setting magnification X is small, at, for
`example, about 1 to 4×, the enlarged image is displayed by digitally zooming in on the wide-angle image 20.
`[0048]
`
`(3) in FIG. 5 is an enlarged image when the setting magnification X is about 4×. It has the telephoto
`image 20 composited in a substantially center position of the digitally zoomed image cut out from the wide-
`angle image 20. Here, a magnification (C) of the telephoto lens of the second imaging module is made to be
`about 5×.
`[0049]
`
`A determination criterion of when to composite the wide-angle image and the telephoto image is
`made to be when the setting magnification X is greater than a specific predetermined magnification A and the
`imaging distance Y is greater than the predetermined length B.
`[0050]
`
`Note that the predetermined magnification A is made to be a magnification at which an image quality
`of the cutout image of the wide-angle image becomes poorer than an image quality of the telephoto image. In
`the above, for example, A is made to be about 4×. Note that when the telephoto magnification C is greater than
`5×, the value of A needs to be increased further. This magnification A can be determined experimentally from
`the magnification C of the telephoto image and the difference in image quality between the telephoto image
`and the wide-angle image. Note that because image quality depends on a performance of a lens system that is
`used and the like, theoretically strict derivation is difficult.
`[0051]
`
`In the above description, A = about 4 and C = about 5, but both A and C may be greater values.
`
`[0052]
`
`As illustrated in FIG. 4, the first imaging module and the second imaging module are close to each
`other (several mm to several tens of mm) and have parallel optical axes. As such, when the imaging distance
`(Y) to the subject is long (several tens of m), center positions of the wide-angle image 17 and the telephoto
`image are substantially equal. Therefore, a function of correcting the center positions of the wide-angle image
`and the telephoto image as in patent literature 3 is unnecessary.
`[0053]
`
`Next, (1) to (4) in FIG. 6 illustrate the enlarged-image generation method in the image control means
`4 when supposed is a situation where the imaging distance (Y) between the mobile terminal device and the
`subject is several tens of meters or less—that is, where the imaging distance Y is the predetermined distance
`B or less.
`[0054]
`
`The setting magnifications in (1) to (4) in FIG. 6 substantially correspond to (1) to (4) in FIG. 5. In
`FIG. 5, at the high magnifications (3) and (4), the telephoto image is composited. In contrast, in FIG. 6, the
`telephoto image is not composited, and the enlarged images are generated entirely from cutout images
`(digital zooms) of the wide-angle image 20.
`[0055]
`
`Next, a reason why the telephoto image is not composited when the imaging distance Y is B or less is
`described.
`[0056]
`
`FIG. 7 illustrates positional relationships between the imaging modules of the mobile terminal device
`and the subject.
`[0057]
`
`The second imaging module performs focus adjustment so the subject is in focus when the imaging
`distance to the subject is long. As such, when the imaging distance to the subject is short ((A) in the diagram),
`it is thought that a telephoto image 23 is blurry.
`[0058]
`
`Therefore, at the close distance (A), a cutout image 22 of the wide-angle image has a more favorable
`image quality than the telephoto image 23.
`[0059]
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`JP 2001-55246 A 2011.3.17
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`Therefore, it is favorable to use the cutout image (digitally zoomed image) of the wide-angle image,
`without compositing the telephoto image in telephoto at a close distance. This is the reason why the telephoto
`image is not composited when the imaging distance Y is B or less.
`[0060]
`
`The above enlarged-image generation method of the image control means 4 is summarized below.
`
`[0061]
`
`When the setting magnification X < A, a digitally zoomed image of the wide-angle image according to
`the setting magnification X is generated.
`[0062]
`
`When the setting magnification X ≥ A and the imaging distance Y ≤ B, a digitally zoomed image of the
`wide-angle image according to the setting magnification X is generated.
`[0063]
`
`When the setting magnification X ≥ A and the imaging distance Y > B, a digitally zoomed image of the
`pasted image according to the setting magnification X is generated from a pasted image where the telephoto
`image is pasted in a center portion of the wide-angle image.
`[0064]
`
`In this manner, because a conventional imaging device made of a wide-angle imaging module and a
`telephoto imaging module simply switches between a wide-angle image and a telephoto image according to
`the setting magnification X alone, a high-magnification image at a close distance is poor. However, the
`imaging device of the present invention described above can suppress degradation of a high-magnification
`image at a close distance.
`[0065]
`
`Furthermore, to suppress degradation of a high-magnification image at a close distance, a
`conventional imaging element needs a focus adjustment function in the telephoto imaging module. As such,
`an actuator or the like is necessary, which causes a size increase, and it is difficult to increase a dynamic range
`of magnification of the telephoto imaging module.
`[0066]
`
`Note that the predetermined distance B is made to be an approximate imaging distance at which the
`image quality of the cutout image 22 of the wide-angle image becomes poorer than the image quality of the
`telephoto image 23. For example, in the above example, it is favorable to make B several tens of meters. When
`the telephoto magnification C increases, the value of B also needs to increase. Note that this magnification B
`can be determined experimentally from the magnification C of the telephoto image and the difference in
`image quality between the telephoto image and the wide-angle image. Note that because image quality
`depends on a performance of a lens system that is used and the like, theoretically strict derivation is difficult.
`[0067]
`
`Next, image qualities of the enlarged image 22 of the wide-angle image 20 and the telephoto image
`21 at the long distance (B) in FIG. 7 are compared.
`[0068]
`
`A pixel density of the first imaging element is defined as N1, and a pixel density of the second imaging
`element is defined as N2. A pixel density of the image 22 that enlarges the wide-angle image 20 by the
`telephoto magnification C is N1/C2.
`[0069]
`
`Therefore, when N1/C2 < N2 is satisfied, a pixel density of the telephoto image 21 is greater than the
`enlarged image 22 of the wide-angle image 20 (the image quality is improved). As such, compositing or
`switching to the telephoto image becomes effective. Conversely, if N1/C2 < N2, there is no reason for a second
`imaging module to exist.
`[0070]
`
`When the telephoto magnification C is greater than 1, the inequality N1/N2 < C2 is established even if
`N2 is small. Therefore, the pixel density N2 of the second imaging element can be made smaller than N1
`without degrading the image quality of the telephoto image 21, which can reduce a price of the second
`imaging module.
`[0071]
`
`Furthermore, a ratio between a total pixel count of the first imaging element and a total pixel count of
`the second imaging element is N1×C2:N2. As such, when the telephoto magnification C is sufficiently greater
`than 1, supposing that N1 ≒ N2, the pixel count of the second imaging element can be up to about 1/C2 times
`
`10
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`50
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`APPL-1010 / Page 9 of 30
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`JP 2001-55246 A 2011.3.17
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`less than the pixel count of the first imaging element. Therefore, by making a size of the second imaging
`element very small compared to the first imaging element, the price of the second imaging module can be
`reduced.
`[0072]
`
`As above, a thin mobile terminal device including an imaging device having a telephoto zoom
`function can be realized by a structure that combines a first imaging module and a second imaging module
`and by image enlargement and compositing methods.
`[Industrial Applicability]
`[0073]
`
`The present invention is useful as a thin mobile terminal device with a built-in telephoto camera of a
`high magnification and can be used as various electronic instruments such as a mobile phone, a mobile game,
`a mobile TV, and a PDA.
`[Reference Signs List]
`[0074]
`
`1
`2
`3
`4
`5
`6
`7
`8
`9
`10
`11
`12
`13
`14
`15
`16
`17
`18
`19
`20
`21
`22
`23
`24
`
`First imaging module
`Second imaging module
`Measurement means
`Image control means
`Display device
`Keying means
`Wide-angle lens system
`First imaging element
`Autofocus adjustment means
`Telephoto lens system
`Second imaging element
`Wide-angle lens
`Actuator
`Distance between wide-angle lens and second imaging element
`Lens
`Mirror
`Mobile terminal device housing
`Optical axis of first imaging module
`Optical axis of second imaging module
`Wide-angle image
`Telephoto image
`Cutout image of wide-angle image
`Telephoto image at close distance
`Imaging distance Y
`
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`20
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`30
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`APPL-1010 / Page 10 of 30
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`[FIG. 1]
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`JP 2001-55246 A 2011.3.17
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`APPL-1010 / Page 11 of 30
`
`

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`[FIG. 2]
`[FIG. 2]
`
`(11)
`(11)
`
`JP 2001-55246 A 2