Patent US4090131A successfully refreshed from Google Patents.
US4090131A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Moving magnet meter having a closed magnetic circuit rotor
Assignee: Individual
•
Filing: 1976-11-04
•
Granted: 1978-05-16
•
Expires: 1996-11-04
Abstract
Abstract There is disclosed a moving magnet meter of inexpensive construction which has the greater sensitivity, linearity and immunity from extraneous fields of moving coil meters. The rotor consists of a closed magnetic circuit through which a permanent magnet flux flows. The flux intersects the turns of a stationary coil through which the current to be measured flows, part of the closed magnetic circuit rotating within the coil. The strength and area of the permanent magnet flux which intersects the coil is substantially constant throughout an operating angle for the rotor of at least 90°. The return torque for the rotor is derived from a stationary permanent magnet which interacts with the rotor flux and provides a return torque which varies linearly with the rotor angle.
Inventors
- 👤 Joseph A. Mas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:12
CPC Classifications
G; G01; G01R; G01R5/00; G01R5/14; G01R5/16
Claims Analysis
Total Claims: 77
Claim 1
Independent Claim
156 words
A meter movement comprising a stationary coil for conducting a current therethrough; rotor means mounted for rotation relative to said coil, said rotor means constituting a closed magnetic circuit with a working gap and having a first flux-carrying section within said coil, a second flux-carrying section outside said coil in facing relation with said first section, and permanent magnet means mounted on at least one of said first and second sections and shaped to provide a permanent magnet flux for flowing through said first and second sections and said working gap and for intersecting a portion of said coil within said working gap, the permanent magnet flux which intersects said coil portion being substantially constant throughout an operating angle for said rotor means; and means for biasing said rotor means to a zero position and for providing a return torque which increases with the angle through which said rotor means is turned from said zero position.
Claim 2
Dependent Claim
156 words
A meter movement comprising a stationary coil for conducting a current therethrough; rotor means mounted for rotation relative to said coil, said rotor means constituting a closed magnetic circuit with a working gap and having a first flux-carrying section within said coil, a second flux-carrying section outside said coil in facing relation with said first section, and permanent magnet means mounted on at least one of said first and second sections and shaped to provide a permanent magnet flux for flowing through said first and second sections and said working gap and for intersecting a portion of said coil within said working gap, the permanent magnet flux which intersects said coil portion being substantially constant throughout an operating angle for said rotor means; and means for biasing said rotor means to a zero position and for providing a return torque which increases with the angle through which said rotor means is turned from said zero position.
Claim 3
Dependent Claim
89 words
A meter movement in accordance with claim 1 wherein said stationary coil is wound on a bobbin; said first flux-carrying section being disposed within said bobbin and said second flux-carrying section being disposed outside said bobbin; said rotor means including a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying sections; the portion of said coil within said working gap being in a plane substantially perpendicular to the intersecting permanent magnet flux lines.
Claim 4
Dependent Claim
26 words
A meter movement in accordance with claim 2 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 5
Dependent Claim
29 words
A meter movement in accordance with claim 3 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux of said rotor means.
Claim 6
Dependent Claim
30 words
A meter movement in accordance with claim 4 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 7
Dependent Claim
32 words
A meter movement in accordance with claim 5 further including means for adjusting the spacing between said stationary permanent magnet and said rotor means to control the sensitivity of the meter movement.
Claim 8
Dependent Claim
16 words
A meter movement in accordance with claim 6 wherein said operating angle is at least 90°.
Claim 9
Dependent Claim
29 words
A meter movement in accordance with claim 1 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux of said rotor means.
Claim 10
Dependent Claim
30 words
A meter movement in accordance with claim 8 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 11
Dependent Claim
32 words
A meter movement in accordance with claim 9 further including means for adjusting the spacing between said stationary permanent magnet and said rotor means to control the sensitivity of the meter movement.
Claim 12
Dependent Claim
64 words
A meter movement in accordance with claim 1 wherein said permanent magnet means includes at least two permanent magnets of opposite polarities mounted on one of said first and second sections and facing the other of said sections for aiding each other and causing a permanent magnet flux to flow in a closed magnetic circuit/working gap path which includes said first and second sections.
Claim 13
Dependent Claim
96 words
A meter movement in accordance with claim 11 wherein said biasing means includes a stationary permanent magnet mounted in facing relationship with one of said first and second flux-carrying sections, said stationary permanent magnet extending around the axis of said rotor means and having a radial width which varies linearly with angle, said stationary permanent magnet aiding the flux of one of said at least two permanent magnets and opposing the flux of the other such that the return torque applied thereby to said rotor means varies linearly with the angular position of said rotor means.
Claim 14
Dependent Claim
30 words
A meter movement in accordance with claim 12 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 15
Dependent Claim
16 words
A meter movement in accordance with claim 13 wherein said operating angle is at least 90°.
Claim 16
Dependent Claim
16 words
A meter movement in accordance with claim 1 wherein said operating angle is at least 90°.
Claim 17
Dependent Claim
91 words
A meter movement in accordance with claim 1 wherein said first and second flux-carrying sections are soft-iron discs mounted for movement together on a common axis extended through said coil, and said permanent magnet means includes two circumferentially-shaped permanent magnets of opposite polarities mounted on each of said discs, all of said permanent magnets being mounted on the facing sides of said discs and being poled to aid each other and to cause a permanent magnet flux to flow in a closed magnetic circuit/working gap path which includes said soft-iron discs.
Claim 18
Dependent Claim
89 words
A meter movement in accordance with claim 16 wherein said stationary coil is wound on a bobbin; said first flux-carrying section being disposed within said bobbin and said second flux-carrying section being disposed outside said bobbin; said rotor means including a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying sections; the portion of said coil within said working gap being in a plane substantially perpendicular to the intersecting permanent magnet flux lines.
Claim 19
Dependent Claim
26 words
A meter movement in accordance with claim 17 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 20
Dependent Claim
29 words
A meter movement in accordance with claim 16 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux of said rotor means.
Claim 21
Dependent Claim
30 words
A meter movement in accordance with claim 19 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 22
Dependent Claim
32 words
A meter movement in accordance with claim 20 further including means for adjusting the spacing between said stationary permanent magnet and said rotor means to control the sensitivity of the meter movement.
Claim 23
Dependent Claim
16 words
A meter movement in accordance with claim 21 wherein said operating angle is at least 90°.
Claim 24
Dependent Claim
16 words
A meter movement in accordance with claim 16 wherein said operating angle is at least 90°.
Claim 25
Dependent Claim
99 words
A meter movement in accordance with claim 16 wherein said biasing means includes a stationary permanent magnet mounted in facing relationship with one of said first and second flux-carrying sections, said stationary permanent magnet extending around the axis of said rotor means and having a radial width which varies linearly with angle, said stationary permanent magnet aiding the flux of one of the two permanent magnets on said one flux-carrying section and opposing the flux of the other such that the return torque applied thereby to said rotor means varies linearly with the angular position of said rotor means.
Claim 26
Dependent Claim
97 words
A meter movement in accordance with claim 1 wherein said first and second flux-carrying sections are soft-iron cylinders each closed at one end and mounted for movement together on a common axis extended through said coil, and said permanent magnet means includes two circumferentially-shaped permanent magnets of opposite polarities mounted around each of said cylinders, all of said permanent magnets being mounted on the facing surfaces of said cylinders and being poled to aid each other and to cause a permanent magnet flux to flow in a closed magnetic circuit/working gap path which includes said soft-iron cylinders.
Claim 27
Dependent Claim
89 words
A meter movement in accordance with claim 25 wherein said stationary coil is wound on a bobbin; said first flux-carrying section being disposed within said bobbin and said second flux-carrying section being disposed outside said bobbin; said rotor means including a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying sections; the portion of said coil within said working gap being in a plane substantially perpendicular to the intersecting permanent magnet flux lines.
Claim 28
Dependent Claim
26 words
A meter movement in accordance with claim 26 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 29
Dependent Claim
16 words
A meter movement in accordance with claim 25 wherein said operating angle is at least 90°.
Claim 30
Dependent Claim
90 words
A meter movement in accordance with claim 1 wherein said biasing means includes a stationary permanent magnet mounted in facing relationship with one of said first and second flux-carrying sections, said stationary permanent magnet extending around the axis of said rotor means and having a radial width which varies as a function of angle, said stationary permanent magnet reacting with the flux of said rotor means such that the return torque applied thereby to said rotor means varies in a predetermined manner with the angular position of said rotor means.
Claim 31
Dependent Claim
213 words
A moving magnet meter comprising: a stationary coil for carrying a current to be measured, first and second flux-carrying elements, at least one of said elements being magnetized, said first flux-carrying element being mounted within said coil for rotatable movement relative to said coil, said second flux-carrying element being mounted outside said coil for rotatable movement with said first flux-carrying element relative to said coil, a closed magnetic circuit including said first flux-carrying element, a first air gap between said first flux-carrying element and said second flux-carrying element, said second flux-carrying element, and a second air gap between said second flux-carrying element and said first flux-carrying element, a portion of the flux of said magnetized element flowing through said closed magnetic circuit, a first portion of said coil being positioned in said first air gap and a second portion of said coil being positioned in said second air gap, a portion of the flux in said closed magnetic circuit passing through said first and second coil portions in a direction substantially perpendicular to the turns of said coil, and means for biasing said first and second flux-carrying elements to a zero position and for providing a return force which increases with the angle through which said elements are turned from said zero position.
Claim 32
Dependent Claim
213 words
A moving magnet meter comprising: a stationary coil for carrying a current to be measured, first and second flux-carrying elements, at least one of said elements being magnetized, said first flux-carrying element being mounted within said coil for rotatable movement relative to said coil, said second flux-carrying element being mounted outside said coil for rotatable movement with said first flux-carrying element relative to said coil, a closed magnetic circuit including said first flux-carrying element, a first air gap between said first flux-carrying element and said second flux-carrying element, said second flux-carrying element, and a second air gap between said second flux-carrying element and said first flux-carrying element, a portion of the flux of said magnetized element flowing through said closed magnetic circuit, a first portion of said coil being positioned in said first air gap and a second portion of said coil being positioned in said second air gap, a portion of the flux in said closed magnetic circuit passing through said first and second coil portions in a direction substantially perpendicular to the turns of said coil, and means for biasing said first and second flux-carrying elements to a zero position and for providing a return force which increases with the angle through which said elements are turned from said zero position.
Claim 33
Dependent Claim
67 words
A moving magnet meter in accordance with claim 30 wherein said stationary coil is wound on a bobbin; said first flux-carrying element being disposed within said bobbin and said second flux-carrying element being disposed outside said bobbin; and further including a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying elements.
Claim 34
Dependent Claim
30 words
A moving magnet meter in accordance with claim 31 wherein said bobbin is made of conducting material to provide damping for the turning of said first and second flux-carrying elements.
Claim 35
Dependent Claim
32 words
A moving magnet meter in accordance with claim 30 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the flux of at least one of said flux-carrying elements.
Claim 36
Dependent Claim
34 words
A moving magnet meter in accordance with claim 33 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said first and second flux-carrying elements.
Claim 37
Dependent Claim
35 words
A moving magnet meter in accordance with claim 34 further including means for adjusting the spacing between said stationary permanent magnet and said at least one flux-carrying element to control the sensitivity of the meter.
Claim 38
Dependent Claim
38 words
A moving magnet meter in accordance with claim 30 wherein the angle through which said first and second flux-carrying elements turn varies linearly with the current carried by said coil through an operating angle of at least 90°.
Claim 39
Dependent Claim
89 words
A moving magnet meter in accordance with claim 30 wherein said biasing means includes a stationary permanent magnet mounted in facing relationship with one of said first and second flux-carrying elements, said stationary permanent magnet extending around the axis of said elements and having a radial width which varies with angle, said stationary permanent magnet reacting with a portion of the flux in said closed magnetic circuit such that the return force applied thereby to said elements varies in a predetermined manner with the angular position of said elements.
Claim 40
Dependent Claim
30 words
A moving magnet meter in accordance with claim 37 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said elements.
Claim 41
Dependent Claim
188 words
A moving magnet meter comprising: a stationary coil for carrying a current to be measured, first and second magnets, said first magnet being mounted within said coil for rotatable movement relative to said coil, said second magnet being mounted outside said coil for rotatable movement with said first magnet relative to said coil, a magnetic circuit comprising said first magnet, a first air gap between said first magnet and said second magnet, said second magnet, and a second air gap between said second magnet and said first magnet, a portion of the flux of said magnets flowing through said magnetic circuit, a portion of said coil being positioned in said first air gap and a portion of said coil being positioned in said second air gap, a portion of the flux in said magnetic circuit passing through said first and second coil portions in a direction substantially perpendicular to the turns of said coil, and means for biasing said first and second magnets to a zero position and for providing a return force which increases with the angle through which said magnets are turned from said zero position.
Claim 42
Dependent Claim
188 words
A moving magnet meter comprising: a stationary coil for carrying a current to be measured, first and second magnets, said first magnet being mounted within said coil for rotatable movement relative to said coil, said second magnet being mounted outside said coil for rotatable movement with said first magnet relative to said coil, a magnetic circuit comprising said first magnet, a first air gap between said first magnet and said second magnet, said second magnet, and a second air gap between said second magnet and said first magnet, a portion of the flux of said magnets flowing through said magnetic circuit, a portion of said coil being positioned in said first air gap and a portion of said coil being positioned in said second air gap, a portion of the flux in said magnetic circuit passing through said first and second coil portions in a direction substantially perpendicular to the turns of said coil, and means for biasing said first and second magnets to a zero position and for providing a return force which increases with the angle through which said magnets are turned from said zero position.
Claim 43
Dependent Claim
64 words
A moving magnet meter in accordance with claim 39 wherein said stationary coil is wound on a bobbin; said first magnet being disposed within said bobbin and said second magnet being disposed outside said bobbin; and further including a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second magnets.
Claim 44
Dependent Claim
29 words
A moving magnet meter in accordance with claim 40 wherein said bobbin is made of conducting material to provide damping for the turning of said first and second magnets.
Claim 45
Dependent Claim
31 words
A moving magnet meter in accordance with claim 39 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the flux of at least one of said magnets.
Claim 46
Dependent Claim
33 words
A moving magnet meter in accordance with claim 42 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said first and second magnets.
Claim 47
Dependent Claim
34 words
A moving magnet meter in accordance with claim 43 further including means for adjusting the spacing between said stationary permanent magnet and said at least one magnet to control the sensitivity of the meter.
Claim 48
Dependent Claim
37 words
A moving magnet meter in accordance with claim 39 wherein the angle through which said first and second magnets turn varies linearly with the current carried by said coil through an operating angle of at least 90°.
Claim 49
Dependent Claim
90 words
A moving magnet meter in accordance with claim 39 wherein said biasing means includes a stationary permanent magnet mounted in facing relationship with one of said first and second magnets, said stationary permanent magnet extending around the axis of said magnets and having a radial width which varies with angle, said stationary permanent magnet reacting with a portion of the flux of at least one of said magnets such that the return force applied thereby to said elements varies in a predetermined manner with the angular position of said elements.
Claim 50
Dependent Claim
30 words
A moving magnet meter in accordance with claim 46 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said elements.
Claim 51
Dependent Claim
132 words
A cogless meter movement comprising a stationary coil for conducting a current therethrough; rotor means mounted for rotation relative to said coil, said rotor means having a closed magnetic circuit with a working gap and a fixed reluctance independent of rotor displacement for conducting a predetermined constant permanent magnet flux therethrough, said rotor means being mounted such that for any displacement within the operating range the permanent magnet flux in said working gap intersects a portion of said coil, the permanent magnet flux which intersects said coil portion being substantially constant throughout the operating range of said rotor means; and means for biasing said rotor means to a zero position and for providing a return torque which increases with the angle through which said rotor means is turned from said zero position.
Claim 52
Dependent Claim
132 words
A cogless meter movement comprising a stationary coil for conducting a current therethrough; rotor means mounted for rotation relative to said coil, said rotor means having a closed magnetic circuit with a working gap and a fixed reluctance independent of rotor displacement for conducting a predetermined constant permanent magnet flux therethrough, said rotor means being mounted such that for any displacement within the operating range the permanent magnet flux in said working gap intersects a portion of said coil, the permanent magnet flux which intersects said coil portion being substantially constant throughout the operating range of said rotor means; and means for biasing said rotor means to a zero position and for providing a return torque which increases with the angle through which said rotor means is turned from said zero position.
Claim 53
Dependent Claim
97 words
A cogless meter movement in accordance with claim 48 wherein said stationary coil is wound on a bobbin; and said rotor means includes a first flux-carrying section disposed within said bobbin and a second flux-carrying section disposed outside said bobbin and a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying sections; the portion of said coil within the working gap between said first and second flux-carrying sections being in a plane substantially perpendicular to the intersecting permanent magnet flux lines.
Claim 54
Dependent Claim
27 words
A cogless meter movement in accordance with claim 49 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 55
Dependent Claim
30 words
A cogless meter movement in accordance with claim 50 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux of said rotor means.
Claim 56
Dependent Claim
31 words
A cogless meter movement in accordance with claim 51 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 57
Dependent Claim
33 words
A cogless meter movement in accordance with claim 52 further including means for adjusting the spacing between said stationary permanent magnet and said rotor means to control the sensitivity of the meter movement.
Claim 58
Dependent Claim
17 words
A cogless meter movement in accordance with claim 53 wherein said operating range is at least 90°.
Claim 59
Dependent Claim
30 words
A cogless meter movement in accordance with claim 48 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux of said rotor means.
Claim 60
Dependent Claim
31 words
A cogless meter movement in accordance with claim 55 further including means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 61
Dependent Claim
33 words
A cogless meter movement in accordance with claim 56 further including means for adjusting the spacing between said stationary permanent magnet and said rotor means to control the sensitivity of the meter movement.
Claim 62
Dependent Claim
134 words
A cogless meter movement in accordance with claim 48 wherein said stationary coil is wound on a bobbin; and said rotor means includes a first flux-carrying section disposed within said bobbin and a second flux-carrying section disposed outside said bobbin, permanent magnet means mounted on each of said flux-carrying sections facing and aiding each other for causing said permanent magnet flux to flow in a closed magnet circuit/working gap path which includes said first and second flux-carrying sections, and a shaft mounted for rotation relative to said bobbin and passing through said bobbin, said shaft being secured to both of said first and second flux-carrying sections; the portion of said coil within the working gap between said first and second flux-carrying sections being in a plane substantially perpendicular to the intersecting permanent magnet lines.
Claim 63
Dependent Claim
51 words
A cogless meter movement in accordance with claim 58 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux in said rotor means and means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 64
Dependent Claim
17 words
A cogless meter movement in accordance with claim 59 wherein said operating range is at least 90°.
Claim 65
Dependent Claim
25 words
A cogless meter movement in accordance with claim 59 wherein the operation of the movement is linear throughout an operating range of at least 90°.
Claim 66
Dependent Claim
27 words
A cogless meter movement in accordance with claim 61 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 67
Dependent Claim
25 words
A cogless meter movement in accordance with claim 58 wherein the operation of the movement is linear throughout an operating range of at least 90°.
Claim 68
Dependent Claim
27 words
A cogless meter movement in accordance with claim 63 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 69
Dependent Claim
51 words
A cogless meter movement in accordance with claim 48 wherein said biasing means includes a stationary permanent magnet mounted for reacting with the permanent magnet flux in said rotor means and means for adjusting the angular position of said stationary permanent magnet to control the zero position of said rotor means.
Claim 70
Dependent Claim
17 words
A cogless meter movement in accordance with claim 65 wherein said operating range is at least 90°.
Claim 71
Dependent Claim
25 words
A cogless meter movement in accordance with claim 65 wherein the operation of the movement is linear throughout an operating range of at least 90°.
Claim 72
Dependent Claim
27 words
A cogless meter movement in accordance with claim 48 wherein said bobbin is made of conducting material to provide damping for the movement of said rotor means.
Claim 73
Dependent Claim
172 words
A substantially cogless electro-mechanical meter comprising: a stationary coil, a rotatable closed magnetic circuit, said magnetic circuit being mounted for rotation about an axis, said magnetic circuit including: first and second ferro-magnetic members spaced from each other by a working gap, at least one of said ferro-magnetic members having a permanent magnetic portion, the flux of said permanent magnetic portion having a path that is completed through said working gap and the other of said ferro-magnetic members, said coil extending through said working gap, said flux intersecting a portion of said coil within said working gap, the interaction between said flux and any current through said portion of said coil producing a torque tending to rotate said magnetic circuit about said axis, said permanent magnetic portion of said at least one of said ferro-magnetic members including a pole face shaped to provide a substantially constant flux intersecting said portion of said coil throughout a predetermined angle of rotation of said coil, and means for providing a return torque for said magnetic circuit.
Claim 74
Dependent Claim
172 words
A substantially cogless electro-mechanical meter comprising: a stationary coil, a rotatable closed magnetic circuit, said magnetic circuit being mounted for rotation about an axis, said magnetic circuit including: first and second ferro-magnetic members spaced from each other by a working gap, at least one of said ferro-magnetic members having a permanent magnetic portion, the flux of said permanent magnetic portion having a path that is completed through said working gap and the other of said ferro-magnetic members, said coil extending through said working gap, said flux intersecting a portion of said coil within said working gap, the interaction between said flux and any current through said portion of said coil producing a torque tending to rotate said magnetic circuit about said axis, said permanent magnetic portion of said at least one of said ferro-magnetic members including a pole face shaped to provide a substantially constant flux intersecting said portion of said coil throughout a predetermined angle of rotation of said coil, and means for providing a return torque for said magnetic circuit.
Claim 75
Dependent Claim
36 words
The meter of claim 69 wherein said working gap has first and second portions at first and second locations in said magnetic circuit, said coil extending through said first and second portions of said working gap.
Claim 76
Dependent Claim
15 words
The meter of claim 70 wherein said predetermined angle of rotation is at least 90°.
Claim 77
Dependent Claim
15 words
The meter of claim 69 wherein said predetermined angle of rotation is at least 90°.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-05-15 | 1981-11-14 | 1982-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-15 | 1985-11-14 | 1986-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-15 | 1989-11-14 | 1990-05-16 | $7700.00 | Window Closed / Lapsed |