WO2016108092A1 - Module téléobjectif miniature et appareil de prise de vues utilisant un tel module - Google Patents

Module téléobjectif miniature et appareil de prise de vues utilisant un tel module Download PDF

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Publication number
WO2016108092A1
WO2016108092A1 PCT/IB2015/050043 IB2015050043W WO2016108092A1 WO 2016108092 A1 WO2016108092 A1 WO 2016108092A1 IB 2015050043 W IB2015050043 W IB 2015050043W WO 2016108092 A1 WO2016108092 A1 WO 2016108092A1
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WIPO (PCT)
Prior art keywords
lens
telephoto
telephoto lens
ttl
camera
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Application number
PCT/IB2015/050043
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English (en)
Inventor
Michael Dror
Ephraim Goldenberg
Gal Shabtay
Original Assignee
Corephotonics Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corephotonics Ltd. filed Critical Corephotonics Ltd.
Priority to PCT/IB2015/050043 priority Critical patent/WO2016108092A1/fr
Publication of WO2016108092A1 publication Critical patent/WO2016108092A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
    • G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
    • G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses

Definitions

  • the present invention is generally in the field of imaging techniques, and relates to a camera and mobile electronic devices utilizing such a camera.
  • Digital camera modules are currently being incorporated into a variety of portable electronic devices. Such devices include for example mobile phones (e.g. smartphones), personal data assistants (PDAs), computers, and so forth. Digital camera modules for use in portable devices have to meet certain requirements such as good quality imaging, small footprint, as well as low weight.
  • a multi-aperture imaging system comprises a first camera with a first sensor that captures a first image and a second camera with a second sensor that captures a second image.
  • the two cameras have either identical or different FOVs.
  • Either image may be chosen to be a primary or an auxiliary image, based on a zoom factor.
  • An output image with a point of view determined by the primary image is obtained by registering the auxiliary image to the primary image.
  • the technique described in W014199338 relates to a dual-aperture zoom digital camera operable in both still and video modes.
  • the camera includes Wide and Tele imaging sections with respective lens/sensor combinations and image signal processors and a camera controller operatively coupled to the Wide and Tele imaging sections.
  • the controller is configured to combine in still mode at least some of the Wide and Tele image data to provide a fused output image from a particular point of view, and to provide, without fusion, continuous zoom video mode output images, each output image having a given output resolution.
  • the video mode output images are provided with a smooth transition when switching between a lower zoom factor (ZF) value and a higher ZF value or vice versa. At the lower ZF the output resolution is determined by the Wide sensor, while at the higher ZF value the output resolution is determined by the Tele sensor.
  • ZF zoom factor
  • the requirements for the camera modules for use in such devices are related to the size, weight and image quality of the camera. Moreover, these requirements become more essential when the camera module is to be installed within the portable device, unlike other external camera units attachable to the portable device.
  • the dimensions of the camera optics should be as small as possible in order to be suitable to operate with commonly used detectors and to fit the thickness of the device in which the camera is installed (preferably without protruding from the device's casing), while the trend in such devices is to reduce the thickness as much as possible.
  • TTLs total track lengths
  • the TTL is typically defined as the maximal distance between the object-side surface of the lens module and an image plane IP defined by such a lens module (where the sensing surface of a camera detector is placed).
  • the TTL is larger than the effective focal length (EFL) of the lens module, which is equal to the distance between the effective principal plane of the lens and its focal plane (which substantially coincides with image plane IP).
  • the lens (or lens module) has front and rear principal planes, which have the property that a ray emerging from the lens appears to have crossed the rear principal plane at the same distance from the axis that that ray appeared to cross the front principal plane, as viewed from the front of the lens. This means that the lens can be treated as if all of the refraction occurred at the principal planes.
  • the principal planes are crucial in defining the optical properties of the system, since it is the distance of the object and image from the front and rear principal planes that determine the magnification of the system.
  • the principal points are the points where the principal planes cross the optical axis.
  • the Wide and Tele lenses would have TTLs of about 4.55mm and 9.1mm, respectively. This will result in undesirably long camera modules for use in such a smartphone device.
  • Fig. 1A schematically illustrating that part of incoming light incident on the "higher” lens does not reach the "shorter” lens.
  • a distance between the Tele and Wide lens modules should be as small as possible to meet the overlapping/common FOVs as well as footprint requirements for the camera unit in a portable device.
  • Standard OIS compensates for camera tilt ("CT") by a parallel-to-the image sensor (exemplarily in the X-Y plane) lens movement ("LMV"). Camera tilt causes image blur.
  • LMV camera tilt
  • a telephoto lens for both a single-aperture or multi-aperture (dual) camera unit, the use of a telephoto lens would be advantageous, as such a telephoto lens provides reduced TTL while enabling to maintain the relatively high EFL required for the Tele lens, i.e. for telephoto lens TTL ⁇ EFL.
  • the dimensions of conventional lenses in which the telephoto condition is satisfied do not allow them to be used as integral lenses fully embedded in a thin portable device.
  • the telephoto lens module in order to be used as an integral lens in a modern portable device, has to satisfy the telephoto condition (i.e. TTL ⁇ EFL) while the lens module is to be as short as possible (along the optical path of light passing through it) allowing it to be fully fitted within the portable device casing.
  • a miniature telephoto lens module which is designed with the desired dimensions to enable its integration within a portable device.
  • the miniature telephoto lens module (or telephoto lens unit) is designed to be completely integrated within the casing of a conventional Smartphone, i.e. without protruding therefrom.
  • the disclosed telephoto lens module has a total track lens (TTL) smaller than an effective focal lens (EFL) thereof, and is configured such that its dimension along the optical axis is desirably small, i.e. about 4- 15mm or less (e.g. suitable to be fitted in a portable device having a casing as small as 4mm).
  • the telephoto lens unit comprises multiple lens elements made of at least two different polymer materials having different Abbe numbers.
  • the multiple lens elements comprise a first group of at least three lens elements being a telephoto lens assembly, and a second group of at least two lens elements being a field lens assembly.
  • the first group of lens elements comprises, in order from the object plane to the image plane along an optical axis of the telephoto lens unit: a first lens having positive optical power and a pair of second and third lenses having together negative optical power such that said telephoto lens assembly provides a telephoto optical effect of said telephoto lens unit and wherein said second and third lenses are each made of one of said at least two different polymer materials having a different Abbe number, for reducing chromatic aberrations of said telephoto lens.
  • the second group of lens elements is configured to correct field curvature of said telephoto lens assembly, and said field lens module comprises two or more of said lens elements made of the different polymer materials respectively having different Abbe numbers, and configured to compensate for residual chromatic aberrations of said telephoto lens assembly dispersed during light passage through an effective gap located between the telephoto and field lens assemblies.
  • the effective gap is larger than 1/5 of the TTL of the telephoto lens unit, thereby allowing sufficient field separation for reducing chromatic aberration.
  • an optical lens unit comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a thickness d2 on an optical axis and separated from the first lens element by a first air gap, a third lens element with negative refractive power and separated from the second lens element by a second air gap, a fourth lens element having a positive refractive power and separated from the third lens element by an effective third air gap, and a fifth lens element having negative refractive power, separated from the fourth lens element by an effective fourth air gap, the fifth lens element having a thickness d 5 on the optical axis.
  • An optical lens unit may further include a stop, positioned before the first lens element, a glass window disposed between the image-side surface of the fifth lens element and an image sensor with an image plane on which an image of the object is formed.
  • Each lens element has two surfaces, each surface having a respective diameter.
  • the largest diameter among all lens elements is defined as an "optical diameter" of the lens assembly.
  • TTL is defined as the distance on an optical axis between the object-side surface of the first lens element and an image plane where the image sensor is placed.
  • EFL has its regular meaning, as mentioned above.
  • TTL is smaller than the EFL, i.e. the TTL/EFL ratio is smaller than 1.0.
  • the TTL/EFL ratio is smaller than 0.9.
  • the TTL/EFL ratio is about 0.85.
  • the lens assembly has an F number F# ⁇ 3.2.
  • the focal length of the first lens element fl is smaller than TTL/2
  • the first, third and fifth lens elements have each an Abbe number ("Vd") greater than 50
  • the second and fourth lens elements have each an Abbe number smaller than 30
  • the first air gap is smaller than d ⁇ JI
  • the effective third air gap is greater than TTL/5
  • the effective fourth air gap is smaller than 1.5d 5 TTL/50.
  • the surfaces of the lens elements may be aspheric.
  • the first lens element with positive refractive power allows the TTL of the lens unit to be favorably reduced.
  • the combined design of the first, second and third lens elements plus the relative short distances between them enable a long EFL and a short TTL.
  • the ratio TTL/EFL ⁇ 1.0 and minimal chromatic aberration are obtained by fulfilling the relationship 1.2xlf3l > If2l > 1.5xfl, where "f ' indicates the lens element effective focal length and the numerals 1, 2, 3, 4, 5 indicate the lens element number.
  • the relatively large effective gap between the third and the fourth lens elements plus the combined design of the fourth and fifth lens elements assist in bringing all fields' focal points to the image plane. Also, because the fourth and fifth lens elements have different dispersions and have respectively positive and negative power, they help in minimizing chromatic aberration.
  • the telephoto lens module disclosed herein may be advantageously adapted to be incorporated in a mobile phone camera that uses a typical 1/4' or 1/3' image sensor.
  • the TTL of the telephoto lens module to be competitive with known mobile phone cameras with 1/4' image sensors, it would be advantageous for the TTL of the telephoto lens module to be smaller than 5.5 mm and the largest lens diameter to be smaller than 4 mm.
  • the TTL of the telephoto lens module to be smaller than 6.5 mm and the largest lens diameter to be smaller than 5 mm.
  • an optical lens unit configured to provide an image on an entire area of a 1/4" image sensor, the lens unit comprising five lens elements and having a TTL smaller than 5.5 mm, an EFL larger than 5.9 mm, and an optical diameter smaller than
  • an optical lens unit operative to provide an image on an entire area of a 1/3" image sensor, the lens unit comprising five lens elements and having a TTL smaller than 6.2 mm, an EFL larger than 6.8 mm, and an optical diameter smaller than
  • lens elements made of polymer material such as plastic. While lenses made of polymer material are advantageous for reducing the price tag of the telephoto lens module as well as its weight, there are very few polymer materials which are suitable for this purpose. This is different to glass lenses which can be made of a variety of different glass materials, each characterized by a different Abbe number. The scarcity in polymer materials presents a challenge when designing lenses for a telephoto lens module. This challenge is at least partly due to the limitation in possible combinations of different lenses with different Abbe numbers which can be used for the purpose of correcting field curvature and compensating for chromatic aberrations.
  • a mobile electronic device comprising an internal camera integrated inside a housing of the electronic device, said camera comprising at least one camera unit including a telephoto lens unit which is made of at least two polymer materials.
  • the mobile electronic device can optionally comprise one or more of features (i) to (x) below, in any desired combination or permutation:
  • the telephoto lens has a total track lens (TTL) not exceeding 15mm.
  • the telephoto lens unit comprises multiple lens elements made of at least two different polymer materials having different Abbe numbers, the multiple lens elements comprise a first group of at least three lens elements configured to form a telephoto lens assembly, and a second group of at least two lens elements configured to form a field lens assembly, wherein the field lens assembly is spaced from the telephoto lens assembly by a predetermined effective gap.
  • said at least two different polymer materials comprise at least one plastic material with the Abbe number larger than 50, and at least one plastic material with the Abbe number smaller than 30.
  • the first group of lens elements comprises, in order from an object plane to an image plane along an optical axis of the telephoto lens unit: a first lens having positive optical power and a pair of second and third lenses having together negative optical power such that said telephoto lens assembly provides telephoto optical effect of said telephoto lens unit, and said second and third lenses are each made of one of said at least two different polymer materials having a different Abbe number, for reducing chromatic aberrations of said telephoto lens; and
  • the second group of lens elements is configured to correct field curvature of said telephoto lens assembly, and comprises two or more of said lens elements made of the different polymer materials respectively having different Abbe numbers, and configured to compensate for residual chromatic aberrations of said telephoto lens assembly dispersed during light passage through said effective gap between the telephoto and field lens assemblies.
  • first, third and fifth lens elements have each an Abbe number greater than 50, and the second and fourth lens elements have each an Abbe number smaller than 30.
  • the telephoto lens unit has a TTL smaller than 5.5 mm, an effective focal length (EFL) larger than 5.9 mm, and an optical diameter smaller than 4 mm, thereby enabling to provide an image on an entire area of a 1/4" image sensor.
  • ETL effective focal length
  • the telephoto lens unit has a TTL smaller than 6.2 mm, an effective focal length (EFL) larger than 6.8 mm, and an optical diameter smaller than 5 mm, thereby enabling to provide an image on an entire area of a 1/3" image sensor.
  • ETL effective focal length
  • a camera unit configured for integrating in a mobile electronic device, the camera unit comprising a telephoto lens unit which is made of at least two polymer materials.
  • the camera unit according to this aspect of the presently disclosed subject matter can optionally comprise one or more of features (i) to (x) below, in any desired combination or permutation:
  • the telephoto lens has a total track lens (TTL) not exceeding 15mm.
  • the telephoto lens unit comprises multiple lens elements made of at least two different polymer materials having different Abbe numbers, the multiple lens elements comprise a first group of at least three lens elements configured to form a telephoto lens assembly, and a second group of at least two lens elements configured to form a field lens assembly, wherein the field lens assembly is spaced from the telephoto lens assembly by a predetermined effective gap.
  • said at least two different polymer materials comprise at least one plastic material with the Abbe number larger than 50, and at least one plastic material with the Abbe number smaller than 30.
  • the first group of lens elements comprises, in order from an object plane to an image plane along an optical axis of the telephoto lens unit: a first lens having positive optical power and a pair of second and third lenses having together negative optical power such that said telephoto lens assembly provides telephoto optical effect of said telephoto lens unit, and said second and third lenses are each made of one of said at least two different polymer materials having a different Abbe number, for reducing chromatic aberrations of said telephoto lens; and
  • the second group of lens elements is configured to correct field curvature of said telephoto lens assembly, and comprises two or more of said lens elements made of the different polymer materials respectively having different Abbe numbers, and configured to compensate for residual chromatic aberrations of said telephoto lens assembly dispersed during light passage through said effective gap between the telephoto and field lens assemblies.
  • the first, third and fifth lens elements have each an Abbe number greater than 50
  • the second and fourth lens elements have each an Abbe number smaller than 30.
  • the telephoto lens unit has a TTL smaller than 5.5 mm, an effective focal length (EFL) larger than 5.9 mm, and an optical diameter smaller than 4 mm, thereby enabling to provide an image on an entire area of a 1/4" image sensor.
  • ETL effective focal length
  • the telephoto lens unit has a TTL smaller than 6.2 mm, an effective focal length (EFL) larger than 6.8 mm, and an optical diameter smaller than 5 mm, thereby enabling to provide an image on an entire area of a 1/3" image sensor.
  • ETL effective focal length
  • a telephoto lens unit configured for use in an internal camera of a mobile electronic device, the telephoto lens being made of at least two polymer materials and having a total track lens (TTL) less than 10mm.
  • TTL total track lens
  • a telephoto lens unit having a total track lens (TTL) smaller than an effective focal lens (EFL) thereof, wherein: the telephoto lens unit comprises multiple lens elements made of at least two different polymer materials having different Abbe numbers, said multiple lens elements defining:
  • a telephoto lens assembly comprising at least three of said lens elements comprising, in order from an object plane to an image plane along an optical axis of the telephoto lens unit: a first lens having positive optical power and a pair of second and third lenses having together negative optical power such that said telephoto lens assembly provides telephoto optical effect of said telephoto lens unit and wherein said second and third lenses are each made of one of said at least two different polymer materials having a different Abbe number, for reducing chromatic aberrations of said telephoto lens; and a field lens assembly spaced from the telephoto lens assembly along said optical axis by an effective gap being equal or larger than 1/5 of the TTL of the telephoto lens unit and configured for correcting field curvature of said telephoto lens assembly, and wherein said field lens module comprises two or more of said lens elements made of the different polymer materials respectively having different Abbe numbers, and configured to compensate for residual chromatic aberrations of said telephoto lens assembly dispersed during light passage through said effective gap between the tele
  • Fig. 1A is a schematic illustration demonstrating shadowing and light- blocking problems caused by height differences between Wide and Tele cameras in a dual-aperture camera;
  • Fig. IB is a schematic illustration of a mobile phone device (constituting a portable electronic device) utilizing a camera unit as disclosed herein which is fully integrated inside the smartphone device;
  • Fig. 1C is a schematic illustration of a telephoto lens unit according to the presently disclosed subject matter
  • Fig. 2A is a schematic illustration of a specific configuration of the telephoto lens unit, according to a first example of the presently disclosed subject matter
  • FIG. 2B shows a graph plotting the modulus of the optical transfer function (MTF) vs. focus shift of the entire optical lens unit of Fig. 2A for various fields;
  • FIG. 2C shows a graph plotting the distortion vs. field angle (+Y direction) for the lens unit of Fig. 2A;
  • FIG. 3A is a schematic illustration of another possible configuration of the telephoto lens unit, according to a first example of the presently disclosed subject matter
  • FIG. 3B shows a graph plotting the MTF vs. focus shift of the entire optical lens assembly for various fields in the lens unit of Fig. 3B, according to the second example of the presently disclosed subject matter;
  • FIG. 3C shows a graph plotting the distortion +Y in percent for the lens unit of Fig. 3A;
  • FIG. 4A is a schematic illustration of a specific configuration of the telephoto lens unit, according to a first example of the presently disclosed subject matter
  • FIG. 4B shows a graph plotting the MTF vs. focus shift of the entire optical lens system for various fields in the lens unit of Fig. 4A;
  • FIG. 4C shows a graph plotting the distortion +Y in percent for the lens unit of Fig. 4A;
  • FIG. 5 is a schematic illustration showing the concept of an effective air gap between adjacent lenses in an optical lens unit, according to the presently disclosed subject matter
  • FIG. 6A is a schematic illustration, in perspective cross section, of an example of a dual-aperture zoom camera, with each camera on a separate printed circuit board (PCB), according to the presently disclosed subject matter;
  • PCB printed circuit board
  • FIG. 6B is a schematic illustration, in perspective cross section, of another example of a dual-aperture zoom camera, with each camera on a separate PCB, according to the presently disclosed subject matter;
  • FIG. 7 is a schematic illustration, in perspective cross section, of yet another example of a dual- aperture zoom camera, where both cameras are mounted on a single PCB, according to the presently disclosed subject matter;
  • FIG. 8 is a schematic illustration of an example of a dual-aperture zoom camera that includes an OIS mechanism, according to the presently disclosed subject matter; and FIG. 9 shows schematically a functional block diagram of the camera example of FIG. 8, according to the presently disclosed subject matter.
  • the present invention includes novel configuration of a lens unit in a portable camera, advantageously applicable in a portable electronic device.
  • a portable electronic device 10 is constituted by a mobile phone device (e.g. smartphone).
  • the mobile device is typically a few millimeters thick, e.g. 4mm- 15mm.
  • any modern electronic device equipped with a camera 15 and suitable to be implemented in any such device. This is so since any modern electronic device of the kind specified (i.e. a device including an integral camera unit) is to be as slim as possible, as light as possible, and is to acquire pictures with as good quality as possible.
  • any modern electronic device of the kind specified i.e. a device including an integral camera unit
  • the presently disclosed subject matter includes a novel mobile electronic device 10 which includes an integrated camera unit 15 which is mounted inside the device casing 14.
  • the camera 15 includes at least one telephoto lens unit (not shown here) which is made of polymer materials.
  • the telephoto lens unit is configured such that its total track lens (TTL) is less than 15mm and even less than 10mm, e.g. less than 6mm or even less than 4mm.
  • TTL total track lens
  • the telephoto lens unit 20 is composed of multiple lens elements made of different polymer materials, i.e. materials having different Abbe numbers.
  • the multiple lens elements are configured and arranged to define a telephoto lens assembly 22A and a field lens assembly 22B arranged along an optical axis OA with a predetermined effective gap G between them (as will be described more specifically further below).
  • the telephoto lens assembly 22A is configured to provide the telephoto optical effect of the telephoto lens unit 20.
  • the field lens assembly 22B spaced from the telephoto lens assembly 22A by the predetermined effective gap G is configured for correcting field curvature of the telephoto lens assembly 22A and to compensate for residual chromatic aberrations of the telephoto lens assembly dispersed during light passage through the effective gap G.
  • the telephoto lens unit 20 is characterized by a total track lens (TTL) and an effective focal lens (EFL) such that TTL ⁇ EFL.
  • TTL total track lens
  • ETL effective focal lens
  • the effective gap G between assemblies 22A and 22B is selected to be larger than TTL/5 of the telephoto lens unit 22A, thereby enabling correction of field curvature of telephoto lens assembly 22A by the field lens assembly 22B.
  • the telephoto lens assembly 22A includes three lens elements (generally three or more) LI, L2, L3 (which are shown here schematically and not to scale), where lens LI has positive optical power and lenses L2 and L3 have together negative optical power.
  • Lenses L2 and L3 are made of the first polymer material having a first Abbe number selected for reducing chromatic aberrations of the telephoto lens assembly 22A.
  • the field lens assembly 22B includes two (or more) lens elements L4 and L5 which are made of different polymer materials respectively having different Abbe numbers. These lenses are configured to compensate for residual chromatic aberrations of the telephoto lens assembly 22A dispersed during light passage through the effective gap G between the 22A and 22B.
  • Lenses LI - L5 can be made for example of two plastic materials, one having an Abbe number greater than 50 and the other - smaller than 30.
  • Lenses LI, L3 and L5 are made of plastic with an Abbe number greater than 50
  • lenses L2 and L4 are made of plastic having an Abbe number smaller than 30.
  • the shape (convex or concave) of a lens element surface is defined as viewed from the respective side (i.e. from an object side or from an image side).
  • FIG. 2A shows a schematic illustration of an optical lens unit 100, according to a first example of the presently disclosed subject matter.
  • FIG. 2B shows the MTF vs. focus shift of the entire optical lens unit for various fields in the lens unit configuration 100.
  • FIG. 2C shows the distortion +Y in percent vs. field.
  • lens unit 100 includes, in order from an object side to an image side, a first plastic lens element 102 (also referred to as "LI”) with positive refractive power having a convex object-side surface 102a and a convex or concave image-side surface 102b; a second plastic lens element 104 (also referred to as "L2”) with negative refractive power and having a meniscus convex object-side surface 104a, with an image side surface marked 104b; a third plastic lens element 106 (also referred to as "L3”) with negative refractive power having a concave object-side surface 106a with an inflection point and a concave image-side surface 106b.
  • a first plastic lens element 102 also referred to as "LI”
  • L2 second plastic lens element 104
  • L3 third plastic lens element 106
  • lens unit 100 Further provided in lens unit 100 is a fourth plastic lens element 108 (also referred to as "L4") with positive refractive power having a positive meniscus, with a concave object-side surface marked 108a and an image-side surface marked 108b; and a fifth plastic lens element 110 (also referred to as "L5") with negative refractive power having a negative meniscus, with a concave object- side surface marked 110a and an image-side surface marked 110b. These two lenses define together the field lens assembly (22B in Fig. 1C).
  • the optical lens unit 100 may further optionally include a stop element 101.
  • the telephoto lens unit 100 defines an image plane 114 in which image sensor(s) is/are located, which is not shown here. Also, as exemplified in the figure, an optional glass window 112 is disposed between the image-side surface 110b of fifth lens element 110 and the image plane 114.
  • the first distance - 0.466 mm is measured from the stop to surface 102a
  • the distance LI 1 from surface 102a to surface 102b i.e. the thickness of first lens element 102
  • the air gap L12 between surfaces 102b and 104a is 0.020 mm
  • the distance L21 between surfaces 104a and 104b i.e. thickness d2 of second lens element 104) is 0.246 mm
  • the lens elements in Tables 1 and 2 (as well as in Tables 3-6) are designed to provide an image on an entire 1/3" sensor having dimensions of approximately 4.7 x. 3.52 mm.
  • the optical diameter in all of these lens assemblies is the diameter of the second surface of the fifth lens element. Comment Radius R Distances Nd/Vd Diameter
  • the Abbe number of the first, third and fifth lens element is 57.095.
  • the first air gap between lens elements 102 and 104 has a thickness (0.020 mm) which is less than a tenth of thickness d2 (0.246 mm).
  • the Abbe number of the second and fourth lens elements is 23.91.
  • an effective third air gap G (see below with reference to Table 9) between lens elements 106 and 108 (i.e. the telephoto and field lens assemblies) is greater than TTL/5.
  • an effective fourth air gap (see below with reference to Table 9) between lens elements 108 and 110 is smaller than TTL/50.
  • fl also fulfills the condition fl ⁇ TTL/2, as 2.645 ⁇ 2.952.
  • FIG. 3A shows a schematic illustration of an optical lens unit 200, according to another example of the presently disclosed subject matter.
  • FIG. 3B shows the MTF vs. focus shift of the entire optical lens system for various fields in embodiment 200.
  • FIG. 3C shows the distortion +Y in percent vs. field.
  • lens unit 200 comprises, in order from an object side to an image side: an optional stop 201; a telephoto lens assembly including a first plastic lens element 202 with positive refractive power having a convex object-side surface 202a and a convex or concave image-side surface 202b, a second plastic lens element 204 with negative refractive power, having a meniscus convex object-side surface 204a, with an image side surface marked 204b, and a third plastic lens element 206 with negative refractive power having a concave object-side surface 206a with an inflection point and a concave image-side surface 206b; and a field lens assembly including a fourth plastic lens element 208 with positive refractive power having a positive meniscus, with a concave object-side surface marked 208a and an image-side surface marked 208b, and a fifth plastic lens element 210 with negative refractive power having a negative meniscus, with a con
  • lens unit 200 all lens element surfaces are aspheric. Detailed optical data is given in Table 3, and the aspheric surface data is given in Table 4, wherein the markings and units are the same as in, respectively, Tables 1 and 2. The equation of the aspheric surface profiles is the same as for lens unit 100 described above.
  • the ratio TTL/EFL 0.843.
  • the Abbe number of the first, third and fifth lens elements is 56.18.
  • the first air gap between lens elements 202 and 204 has a thickness (0.129 mm) which is about half the thickness d2 (0.251 mm).
  • the Abbe number of the second lens element is 20.65 and of the fourth lens element is 23.35.
  • the effective third air gap G between lens elements 206 and 208 is greater than TTL/5.
  • the effective fourth air gap between lens elements 208 and 210 is smaller than TTL/50.
  • fl also fulfills the condition fl ⁇ TTL/2, as 2.851 ⁇ 2.950.
  • FIG. 4A shows a schematic illustration of an optical lens unit 300, according to yet a further example of the presently disclosed subject matter.
  • FIG. 4B shows the MTF vs. focus shift of the entire optical lens system for various fields in embodiment 300.
  • FIG. 4C shows the distortion +Y in percent vs. field.
  • Lens unit 300 comprises, in order from an object side to an image side, an optional stop 301; a telephoto lens assembly including a first plastic lens element 302 with positive refractive power having a convex object-side surface 302a and a convex or concave image-side surface 302b, a second plastic lens element 204 with negative refractive power, having a meniscus convex object-side surface 304a, with an image side surface marked 304b, a third plastic lens element 306 with negative refractive power having a concave object-side surface 306a with an inflection point and a concave image-side surface 306b; and a field lens assembly including a fourth plastic lens element 308 with positive refractive power having a positive meniscus, with a concave object-side surface marked 308a and an image-side surface marked 308b, and a fifth plastic lens element 310 with negative refractive power having a negative meniscus, with a concave object-side surface marked 310a and an
  • lens unit 300 all lens element surfaces are aspheric.
  • Detailed optical data is given in Table 5, and the aspheric surface data is given in Table 6, wherein the markings and units are the same as in, respectively, Tables 1 and 2.
  • the equation of the aspheric surface profiles is the same as for lens units 100 and 200.
  • the ratio TTL/EFL 0.863.
  • the Abbe number of the first lens element is 63.1, and of the third and fifth lens elements is 57.09.
  • the first air gap between lens elements 302 and 304 has a thickness (0.029 mm) which is about l/10 th the thickness d2 (0.254 mm).
  • the Abbe number of the second and fourth lens elements is 23.91.
  • the effective third air gap G between lens elements 306 and 308 is greater than TTL/5.
  • the effective fourth air gap between lens elements 308 and 310 is smaller than TTL/50.
  • fl also fulfills the condition fl ⁇ TTL/2, as 2.687 ⁇ 2.952.
  • Tables 7 and 8 provide respectively detailed optical data and aspheric surface data for a fourth embodiment of an optical lens system disclosed herein.
  • the markings and units are the same as in, respectively, Tables 1 and 2.
  • the equation of the aspheric surface profiles is the same as for lens systems 100, 200 and 300.
  • the lens elements in Tables 7 and 8 are designed to provide an image on an entire 1/4" sensor having dimensions of approximately 3.66 x 2.75mm.
  • fl also fulfills the condition fl ⁇ TTL/2, as 2.298 ⁇ 2.64.
  • the first three lens elements achieve essentially a telephoto effect for all fields (angles of object orientation relative to the optical axis), i.e. achieve a strong concentration (by LI) followed by partial collimation (mainly by L2 but also by L3).
  • the fact that all fields need to have essentially the same telephoto effect leads to relatively small distances (small air gaps) between the three lens elements, e.g. especially between LI and L2 (air gap 1).
  • L4 and L5 are mainly field lens elements for reducing field curvature, i.e. their main effect is to cause the focal point for all fields (where the object distance is approximately infinity) to reside on the sensor plane. To achieve this, it is advantageous that for every field, the corresponding rays hit L4 and L5 at different locations, thus enabling separate adjustment for every field ("field separation").
  • the inventors have found that the desired fields' separation is obtainable in a lens unit design characterized by an "effective air gap" G between lenses L3 and L4 (between the telephoto and field lens assemblies, where a larger G leads to larger separation between the fields).
  • FIG. 5 illustrates the concept of the effective air gap between the two adjacent lens elements.
  • an "air gap per field" D rn is defined as the length of the n" 1 field's chief ray along the respective chief ray between adjacent lens elements.
  • each pair of adjacent lens elements e.g. between L3 and L4 and between L4 and L5:
  • the effective air gap between adjacent lens elements reflects an average effective distance between the two surfaces bounding the air gap between the two adjacent lens elements.
  • ray 9 hits the end pixel on the image sensor diagonal.
  • Table 9 shows data on TTL, D Leff -3, D Leff -4, and ratios between the TTL and the effective air gaps for each of lens units 100, 200 and 300 above .
  • D Leff -3 and D Leff -4 were calculated using 9 chief rays, as shown in FIG. 4.
  • a compact optical design requires that the diameter of L5 be as small as possible while providing the required performance. Since the lens and camera footprint is determined by L5 diameter, a small effective air gap, D Leff -4, between lenses L4 and L5 is advantageous in that it allows a small diameter of lens L5 without degrading the optical performance. Effective air gap D Leff -4 is a better indicator of the L5 diameter than the commonly used air gap along the optical axis between L4 and L5. An adequately small L5 diameter may exemplarily be achieved if the effective air gap between the field lenses L4 and L5 is D Leff -4 ⁇ TTL/50.
  • an effective air gap D Leff can be calculated in principle using any combination of two or more chief rays (for example ray 1 and ray 9 in FIG. 4).
  • the "quality" of D Leff calculation improves while considering an increased number of chief rays.
  • the miniature telephoto lens units described above with reference to Figs. 1C and 2 to 5 are designed with a TTL shorter than EFL. Accordingly, due to shorter TTL, such lens units have a smaller field of view, as compared to standard mobile phone lens units. Therefore, it would be particularly useful to use such a telephoto lens unit as a Tele sub-camera lens unit in a dual aperture zoom camera.
  • a dual aperture zoom camera is described in the above-mentioned W014199338 of the same assignee as the present application.
  • the problem discussed above posed by a difference in the TTL/EFL ratios of the conventional Tele and Wide lenses may be solved through use of a standard lens for the Wide camera (TTLw /EFLw > 1.1, typically 1.3) and of a special Telephoto lens design for the Tele camera (TTL T /EFL T ⁇ 1, e.g. 0.87), where the telephoto lens unit is configured as described above, providing the miniature telephoto lens unit.
  • the height difference between the telephoto lens unit and the Wide lens unit is also reduced to approximately 1.65mm, thus reducing shadowing and light blocking problems.
  • TTL T /TTL W is in the range 1.0-1.25.
  • EFL W may be in the range 2.5-6mm and EFL T may be in the range 5- 12mm.
  • FIG. 6A shows schematically in perspective cross section an example of a dual-aperture zoom camera device 600.
  • Camera device 600 includes two camera unit 602 and 604. It should be understood that the two camera units may be associated with common or separate detectors (pixel matrix and their associated read out circuits). Thus, the two camera units are actually different in their optics, i.e. in the imaging channels defined by the wide and telephoto lens units.
  • Each camera unit may be mounted on a separate PCB (respectively 605a and 605b) including the read out circuit, and includes a lens unit (respectively 606 and 608), and an image sensor including a pixel matrix (respectively 614 and 616), and an actuator (respectively 610 and 612) associated with a focusing mechanism.
  • the two PCBs lie in the same plane. It should be understood that in the embodiment where the readout circuits of the two imaging channels are in the same plane, a common PCB can be used, as will be described further below.
  • the two camera units are connected by a case 618.
  • camera 602 includes a Wide lens unit and camera 604 includes a Telephoto lens unit, the TTL T of the lens unit defining the respective camera height H.
  • the Wide and Telephoto lens units provide respectively main and auxiliary optical/imaging paths, enabling to use the main image for interpreting the auxiliary image data.
  • FIG. 6B shows schematically, in perspective cross, another example of a dual- aperture zoom camera 600' utilizing the principles of the invention.
  • Camera 600' is generally similar to the above-described camera 600, and the common components are shown in the figure in a self-explanatory manner and thus are not indicated by reference numbers.
  • the camera unit 602 e.g. a Wide lens camera
  • camera unit 604 e.g. a Telephoto lens camera
  • the two PCBs lie in different planes. This enables the object side principal planes of the Wide and Telephoto lens units to be close one to the other, thus reducing the dependency of magnification factor in the two units on the object distance.
  • FIG. 7 shows schematically, in perspective cross section, yet another example of a dual-aperture zoom camera 700.
  • Camera 700 is similar to cameras 600 and 600' in that it includes two camera units 702 and 704 with respective lens units 706 and 708, respective actuators 710 and 712 and respective image sensors 714 and 716.
  • the two camera units 702 and 704 are mounted on a single (common) PCB 705.
  • the mounting on a single PCB and the minimizing of a distance "d" between the two camera units minimizes and may even completely avoid camera movement (e.g. associated with mishaps such as drop impact).
  • the dimensions of camera 700 may be in the same range as those of cameras 600 and 600'.
  • the footprint W x L and the weight of camera 700 are smaller than that of cameras 600 and 600'. Mishaps such as drop impact may cause a relative movement between the two cameras after system calibration, changing the pixel matching between the Tele and Wide images and thus preventing fast reliable fusion of the Tele and Wide images. Therefore, such effects should preferably be eliminated.
  • Standard OIS compensates for camera tilt ("CT"), i.e., image blur, by a parallel-to-the image sensor (exemplarily in the X-Y plane) lens movement ("LMV").
  • CT camera tilt
  • LMV lens movement
  • CT is in radians and EFL is in mm.
  • both lenses cannot move together and achieve optimal tilt compensation for both of the respective camera units. More specifically, since the tilt is the same for both camera units, a movement that will compensate for the tilt for the Wide camera unit will be insufficient to compensate for the tilt for the Telephoto camera unit, and vice versa.
  • OIS actuators for the two camera units respectively can achieve simultaneous tilt compensation for both of them, but the entire system would be complex and costly, which is undesirable for portable electronic devices.
  • FIG. 8 shows an example of a dual-aperture zoom camera 800 (similar to the above-described camera 700) that includes two camera units 802 and 804 mounted either on a single PCB 805 (as shown in this example) or on separate PCBs.
  • Each camera unit includes a lens unit (respectively 806 and 808), an actuator (respectively 810 and 812) and an image sensor (respectively 814 and 816).
  • the two actuators are rigidly mounted on a rigid base 818 that is flexibly connected to the PCB (or PCBs) through flexible elements 820.
  • Base 818 is movable by an OIS mechanism (not shown) controlled by an OIS controller 902 (shown in FIG. 9).
  • the OIS controller 902 is coupled to, and receives camera tilt information from a tilt sensor (e.g. a gyroscope) 904 (FIG. 9). More details of an example of an OIS procedure as disclosed herein are given below with reference to FIG. 9.
  • the two camera units are separated by a small distance "d", e.g. lmm. This small distance between camera units also reduces the perspective effect enabling smoother zoom transition between the camera units.
  • the two image sensors 814 and 816 may be mounted on separate PCBs that are rigidly connected, thereby enabling adaptation of an OIS mechanism to other system configurations, for example those described above with reference to FIGS. 6 A and 6B.
  • a magnetic shield plate may be used, e.g. as described in co-owned US patent application No. 14/365,718 titled “Magnetic shielding between voice coil motors in a dual-aperture camera", which is incorporated herein by reference in its entirety. Such a magnetic shield plate may be inserted in the gap (with width d) between the Wide and Tele camera units.
  • the dimensions of camera 800 may be in the same range as those of cameras 600, 600' and 700.
  • FIG. 9 exemplifies the camera operation, utilizing a tilt sensor 904 which dynamically measures the camera tilt (which is the same for both the Wide and Tele camera units).
  • an OIS controller 902 electronic circuit including hardware/software components
  • the LMV is for example in the X-Y plane.
  • the OIS controller 902 is configured to provide a LMV equal to CT*EFLZF, where "EFL ZF " is chosen according to the user-defined zoom factor, ZF.
  • EFL ZF EFL W
  • LMV CT*EFL W
  • EFL ZF EFL W
  • LMV CT* EFL T
  • EFL ZF EFL T
  • CT* EFL T CT* EFL T
  • the present invention provides a novel approach for configuring a camera device suitable for use in portable electronic devices, in particular smart phones.
  • the present invention solves various problems associated with the requirements for physical parameters of such devices (weight, size), high image quality and zooming effects.

Abstract

La présente invention concerne un appareil de prise de vues destiné à être intégré dans un dispositif électronique mobile ainsi qu'un dispositif électronique mobile, ledit appareil de prise de vues comprenant au moins une unité téléobjectif qui est constituée d'au moins deux matériaux polymères et présente un rapport TTL/EFL inférieur à 1.
PCT/IB2015/050043 2015-01-03 2015-01-03 Module téléobjectif miniature et appareil de prise de vues utilisant un tel module WO2016108092A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3848968A (en) * 1972-12-26 1974-11-19 Polaroid Corp Compact eight element zoom lens with optical compensation
US20030164895A1 (en) * 2001-11-16 2003-09-04 Jarkko Viinikanoja Mobile termanal device having camera system
US20110205635A1 (en) * 2010-02-23 2011-08-25 Largan Precision Co., Ltd. Zoom lens assembly
US20120147193A1 (en) * 2010-12-09 2012-06-14 Apple Inc Back Panel for a Portable Electronic Device with Different Camera Lens Options
WO2013085107A1 (fr) * 2011-12-07 2013-06-13 Song Ji-Hyeon Lentille pour caméra de dispositif de communication mobile personnel et de dispositif électronique
WO2014199338A2 (fr) * 2013-06-13 2014-12-18 Corephotonics Ltd. Appareil photographique numérique à zoom à double ouverture

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3848968A (en) * 1972-12-26 1974-11-19 Polaroid Corp Compact eight element zoom lens with optical compensation
US20030164895A1 (en) * 2001-11-16 2003-09-04 Jarkko Viinikanoja Mobile termanal device having camera system
US20110205635A1 (en) * 2010-02-23 2011-08-25 Largan Precision Co., Ltd. Zoom lens assembly
US20120147193A1 (en) * 2010-12-09 2012-06-14 Apple Inc Back Panel for a Portable Electronic Device with Different Camera Lens Options
WO2013085107A1 (fr) * 2011-12-07 2013-06-13 Song Ji-Hyeon Lentille pour caméra de dispositif de communication mobile personnel et de dispositif électronique
WO2014199338A2 (fr) * 2013-06-13 2014-12-18 Corephotonics Ltd. Appareil photographique numérique à zoom à double ouverture

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