Patent Application
20240247953
Embodiments disclosed herein relate in general to position sensing units, and in particular to position sensing in compact digital cameras included in mobile electronic devices.
Many compact digital cameras that are integrated in handheld electronic devices (“devices”) such as smartphones or tablets use actuators such as voice coil motors (VCMs) or stepper motors, e.g. for actuating a camera lens along a trajectory having a particular direction and range (“stroke” or “L”). The actuation is controlled by a position sensing unit, which is typically based on a magnet assembly (“MA”) that moves relative to a magnetic flux measuring device (MFMD) for example a Hall sensor. For stable control, the position sensing unit must support two conditions: a) it must exhibit linear behavior, i.e. its slope S=AB/Ax must be constant along the entire stroke (“linear range”), where AB is the change in magnetic flux density between two points located at a distance Δx from each other. For example, the linear range of the position sensing unit limits the stroke, and b) the slope S=AB/Ax within the linear range must be sufficiently steep, i.e. it must be above a certain threshold, e.g. S>50 mT or S>200 mT.
Novel Telephoto “(Tele”) cameras entering the market have large effective focal lengths (EFL) of e.g. 10 mm-40 mm for large zoom factors and for Macro photography with high object-to-image magnifications of e.g. 1:1-15:1 at object-lens distances (“u”) of 5 cm-15 cm. Focusing such a large EFL camera to a short u as small as 5 cm-15 cm requires large lens strokes significantly exceeding 1 mm.
Using the thin lens equation 1/EFL=1/u+1/v (“v” being the lens-image distance) and a Tele camera having EFL=25 mm as an example, a lens stroke of about 6.3 mm is required to focus to 10 cm (with respect to focus on infinity). Controlling such large lens strokes cannot be supported by position sensing units used at present in the compact camera industry. Further examples that require large strokes of components are, for example, (i) a 2-state zoom camera described in co-owned international patent application PCT/IB2020/051405, (ii) a pop out mechanism that collapses a camera's total track length (TTL) such as described in the co-owned international patent application PCT/IB2020/058697 and (iii) a continuous zoom camera such as described in co-owned U.S. provisional patent application No. 63/119,853 filed 1 Dec. 2020.
There is need for, and it would be beneficial to have a position sensing unit with a compact form factor that allows realizing position sensing with along large strokes L and with sufficiently large slope S.
In some embodiments, the MA has a symmetry axis parallel to the second direction. In some embodiments, the symmetry axis is located at a center of the middle MA domain.
In some embodiments, D is not constant for different positions within stroke L.
In some embodiments, L/Dmin>15. In some embodiments, L/Dmin>20.
In some embodiments, B at x0 is B0 and B at xmax is Bmax, and a slope S=(B0−Bmax)/L is larger than 10 mT/mm. In some embodiments, S is larger than 100 mT/mm. In some embodiments, S is larger than 1000 mT/mm. In some embodiments, S is larger than 2500 mT/mm.
In some embodiments, the magnetic polarization of the left MA domain is directed towards the MFMD.
In some embodiments, the magnetic polarization of the right MA domain is directed away from the MFMD.
In some embodiments, the magnetic polarization of the middle MA domain is directed parallel or anti-parallel to the first direction.
In some embodiments, a position sensing unit as above or below may be included in a voice coil motor (VCM). In some embodiments, the VCM includes four coils. In some embodiments, the VCM is included in smartphone camera.
In some embodiments, the MFMD is a Hall sensor.
In some embodiments, a value of D between the left MA domain and MFMD is D(x0), wherein a value of D between the right MA domain and the MFMD is D(xmax), wherein a value of D between the middle MA domain and the MFMD is D(xmax/2) and wherein D(x0)≤D(xmax/2) and D(xmax)≤D(xmax/2). In some embodiments, a value of D between the middle MA domain and the MFMD is D(xmax/2) and wherein D(x0)=D(xmax)≤D(xmax/2).
In some embodiments, the left, middle and right MA domains are rectangular. In some embodiments, the left and right MA domains are trapezoids, and the middle MA domain is a convex pentagon. In some embodiments, the left and right MA domains are trapezoids, and the middle MA domain is a concave pentagon.
In some embodiments, the MA additionally includes a fourth MA domain and a fifth MA domain having respective magnetic polarizations, wherein the fourth MA domain is located to the left of the left MA domain and wherein the fifth MA domain is located to the right of the right MA domain. In some embodiments, the magnetic polarization of the fourth MA domain is directed away from the MFMD. In some embodiments, the magnetic polarization of the fifth MA domain is directed towards the MFMD.
In some embodiments, L<20 mm. In some embodiments, L<10 mm. In some embodiments, L<7.5 mm. In some embodiments, L<5 mm.
In some embodiments, L/W>0.5. In some embodiments, L/W>0.75.
In some embodiments, L/H>3. In some embodiments, L/H>5.
Non-limiting examples of embodiments disclosed herein are described below with reference to figures attached hereto that are listed following this paragraph. The drawings and descriptions are meant to illuminate and clarify embodiments disclosed herein, and should not be considered limiting in any way. Like elements in different drawings may be indicated like numerals.
MA 202 includes three rectangular permanent magnets 202a, 202b and 202c having respective magnetic polarizations 204a, 204b and 204c. Magnets 202a and 202c are identical in shape and dimensions, but opposite respective magnetizations 204a and 204c. Magnets 202a and 202c are positioned symmetrically with respect to magnet 202b, i.e. both magnets 202a and 202c are (i) located at a same distance d202 from magnet 202b and (ii) are positioned at a same relative y coordinate ΔH with respect to magnet 202b. A center “C” of MA 202 is located at symmetry axis SA 209 of both magnet 202b and MA 202. MA 202 is shaped symmetrically around C with respect to y. MA 202 has a width W202 and a height H202.
Magnets described herein may be made from any material known to be used in the industry, specifically in digital cameras used in mobile electronic devices such as smartphones, for example any Neodymium based material, e.g. N48H, N48SH etc. x0 and xmax may be chosen so that their middle or symmetry point xS=xmax/2 is located at C, or they may be chosen otherwise. That is, the symmetry axis of the stroke with respect to y is located at xS=xmax/2 and may be identical with the SA 209 of MA 202 located at C (such as shown in
The orthogonal distance between any component included in MA 202 and MFMD 206 is marked “D”. “Orthogonal distance” means that it represents only the y-component of a distance between any component included in MA 202 and MFMD 206. Values of D at points x0, C and xmax are marked respectively D(x0), DC and D(xmax). At x0 and xmax, D has a minimal value Dmin.
As an example, D between magnet 202a and MFMD 206 is D(x0) and D between magnet 202b and MFMD 206 is DC, irrespective from the actual relative distance between magnet 202a and 202b respectively and MFMD 206. As to the relative motion of MA 202 and MFMD 206, in general an actual relative distance is composed of a distance component measured along x and a distance component measured along y. It is noted here that D refers to a distance between a magnet and a packaging device that includes a MFMD, and not to the distance the MFMD itself. In general, a MFMD is included in a packaging device having a housing, wherein the MFMD is located at a MFMD-housing distance of about 50 μm-250 μm from the housing. For calculating the distance between a magnet and the MFMD, the MFMD-housing distance must be added to D. Additionally, it is noted that D is not shown in scale.
In all examples shown herein, D(x0) and D(xmax) can be smaller than or equal to D(x) fulfilling D(x0), D(xmax)≤D(x). The closest distance between one of the magnets and the MFMD Dmin=D(x0)=Dmax. That is, D(x0) and D(xmax) are smaller than or equal to all other distances in that range. In position sensing unit 200, D(x0)=D(xmax)<DC and L/Dmin>10. Typically, Dmin≥0.1 mm.
At x0, magnetic polarization 204a is directed substantially towards MFMD 206. At xmax, magnetic polarization 204c is directed substantially away from MFMD 206. At C, magnetic polarization 204b is directed substantially in parallel or anti-parallel to X. Magnets 202a, 202b and 202c define three MA domains, a left, a middle and a right MA domain respectively, wherein the magnet polarizations of each MA domain are different from each other.
Magnetic flux density B is a function of x, i.e. B=B(x). In L, the slope S=(Bmax−B0)/Ax of B is linear. In all following examples, S is given for an ideally linear slope such as 216 (see
As mentioned, graph 207 in
MA 302 causes a magnetic field (not shown). At C, MFMD 306 is located at De away from MA 302. MA 302 moves along a stroke in x direction relative to MFMD 306. The position of MA 302 along x varies from x0 to xmax. x0 and xmax may be chosen so that their middle or symmetry point xS=xmax/2 is located at C, or they may be chosen otherwise. It is noted that D is not shown in scale.
Between x0 and xmax, orthogonal distance D is a function of x, D=D(x). For 300, D(x0)=D(xmax)<DC, D(x0)=D(xmax)=Dmin and L/Dmin>10. Typically, Dmin>0.1 mm. For the purpose of illustrating the definition of D, D is shown at 2 further, arbitrary positions x1 and x2, where D is given by D(x1) and D(x2) respectively. At x0, magnetic polarization 304a is substantially directed towards MFMD 306. At xmax, 304c is substantially directed away from MFMD 306. At C, 304b is directed substantially parallel or anti-parallel to x. Magnets 302a, 302b and 302c define three MA domains, a left, a middle and a right MA domain respectively, wherein the magnet polarizations of each MA domain are different from each other.
B 309 measured by MFMD 306 is shown versus the x position of MA 202 (“B versus x curve”). B is a function of x, i.e. B=B(x). In L, S=(Bmax−B0)/Ax of B is linear. Example values of given in Table 1. Values of S are given at DC. An advantage of MA 302 over MA 202 is that a B versus x curve within L exhibits a higher linearity. That is, the B vs. x curve of MA 302 varies less from an ideal linear shape such as 216 than the B vs. x curve of MA 202.
MA 402 causes a magnetic field (not shown). At C, MFMD 406 is located at DC away from MA 402. MA 402 moves along a stroke in x direction relative to MFMD 406. The position of MA 402 along x varies from x0 to xmax. x0 and xmax may be chosen so that their middle or symmetry point xS=xmax/2 is located at C, or they may be chosen otherwise.
Between x0 to xmax, orthogonal distance D is a function of x, D=D(x). For 400, D(x0)=D(xmax)<DC, D(x0)=D(xmax)=Dmin and L/Dmin>10. Typically, Dmin>0.1 mm. At x0, the magnetic polarization 404a is substantially directed towards MFMD 406. At xmax, 404c is substantially directed away from MFMD 406. At C, 404b is directed substantially parallel or anti-parallel to X. Magnets 402a, 402b and 402c define three MA domains, a left, a middle and a right MA domain respectively, wherein the magnet polarizations of each MA domain are different from each other. It is noted that D is not shown in scale.
B 409 measured by MFMD 406 is shown versus the x position of MA 202. B is a function of x, i.e. B=B(x). In L, S=(Bmax−B0)/AX of B is linear. Example values of position sensing unit 400 are given in Table 2. Values of S are given at DC. An advantage of MA 402 over MA 202 is that a B versus x curve within L exhibits a higher linearity.
MA 502 causes a magnetic field (not shown). At C, MFMD 506 is located at DC away from MA 502. MA 502 moves along a stroke in x direction relative to MFMD 506. The position of MA 502 along x varies from x0 to xmax. x0 and xmax may be chosen so that their middle or symmetry point xS=xmax/2 is located at C, or they may be chosen otherwise.
Between x0 to xmax, orthogonal distance D is a function of x, D=D(x). For 500, D(x0)=D(xmax)<DC, D(x0)=D(xmax)=Dmin and L/Dmin>10. Typically, Dmin≥0.1 mm. At x0, the magnetic polarization 504a is substantially directed towards MFMD 506. At xmax, 504c is substantially directed away from MFMD 506. At C, 504b is directed substantially parallel or anti-parallel to X. 504d is directed substantially anti-parallel to 504a. 504e is directed substantially anti-parallel to 504c. Additionally to the three MA domains defined by magnets 502a, 502b and 502c, in MA 502 there are two additional MA domains defined by magnets 502d and 502e.
B (not shown) is measured by MFMD 506 versus the x position of MA 202. B is a function of x, i.e. B=B(x). In L, S=(Bmax−B0)/AX of B is linear. Example values of given in Table 3. For the values of magnet sub-assembly including magnets 502a, 502b and 502c see magnets 302a, 302b and 302c of Table 1 respectively. Values of S are given at DC.
An advantage of MA 502 over MA 302 is that a B versus x curve has a higher linearity for the same dimensions of magnets 502a, 502b and 502c (which have the same dimensions as magnets 302a, 302b and 302c).
In VCM 510, the magnetic field caused by position sensing unit 500 additionally provides, together with the magnetic field generated by CA 520, the magnetic field configuration which is required for actuating a relative motion between MA 502 and CA 520 as well as MFMD 506. Typically and with respect to a device that includes VCM 510, MFMD 506 and CA 520 are at rest and MA 502 moves. In some examples for lens focusing in devices that include a camera, MA 502 may be fixedly coupled to the camera's lens for actuating the lens with respect to camera's image sensor which is at rest with respect to the device. An advantage of MA 502 over MA 302 is that it allows a faster VCM actuation.
In other embodiments, a VCM like VCM 510 may include position sensing unit 200, 300 or 400.
While this disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. The disclosure is to be understood as not limited by the specific embodiments described herein, but only by the scope of the appended claims.
Unless otherwise stated, the use of the expression “and/or” between the last two members of a list of options for selection indicates that a selection of one or more of the listed options is appropriate and may be made.
It should be understood that where the claims or specification refer to “a” or “an” element, such reference is not to be construed as there being only one of that element.
Furthermore, for the sake of clarity the term “substantially” is used herein to imply the possibility of variations in values within an acceptable range. According to one example, the term “substantially” used herein should be interpreted to imply possible variation of up to 10% over or under any specified value. According to another example, the term “substantially” used herein should be interpreted to imply possible variation of up to 5% over or under any specified value. According to a further example, the term “substantially” used herein should be interpreted to imply possible variation of up to 2.5% over or under any specified value.
All references mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual reference was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.
This application is a continuation from U.S. patent application Ser. No. 17/628,905 filed Jan. 21, 2022 (now allowed), which was a 371 of international patent application PCT/IB2021/056693 filed Jul. 26, 2021, and claims priority from U.S. Provisional Patent Application No. 63/059,200 filed Jul. 31, 2020, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63059200 | Jul 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17628905 | Jan 2022 | US |
| Child | 18591012 | US |
