The invention relates generally to chairs, and in particular, to a task chair having position-adjustable support arms.
Task chairs are familiar items of furniture commonly used in an office or other occupational environment by persons while working in a seated position. Traditionally, producing a task chair suitable for a broad spectrum of individuals is a difficult endeavor. A primary reason for this difficulty encountered by task chair manufacturers is that users of task chairs vary greatly in their body shape, relative physical size and proportions.
To enhance comfort, manufacturers create task chairs characterized by a high degree of adjustability so that the task chair can be conformed to the body shape, physical size, and proportions of a seated chair user. Most task chairs incorporate manual adjustment features that allow the seated chair user to adjust the shape or movement characteristics of the chair components to a desired configuration. In particular, most task chairs have support arms with rests or pads upon which a person seated in the chair may support or prop their forearms. Seated chair users may need to adjust the position of the pads to customize them after initial assembly of the task chair.
The support arms are adjustable with at least one degree of freedom, such as a vertical height adjustment, for altering the position of the rests relative to the chair seat. In addition, the width between the arm pads may be adjusted by changing the relative position of the two support arms. Traditionally, separate adjustment knobs located on each arm have controlled these two basic movements. As a result, four individual adjustment knobs are required.
Adjustment knobs are prone to snagging power cables and/or vacuum lines attached to medical equipment in use by a user seated in the task chair, which may damage the equipment, the cables and/or the lines or may simply result in an unintentional disconnection. In addition, power cables and vacuum lines may wind about the adjustment knobs during use so that the length is effectively reduced. The likelihood for a seated user to experience such difficulties increases with an increase in the number of adjustment knobs.
What is needed, therefore, is a task chair that addresses these and other deficiencies of conventional task chairs.
In an embodiment of the present invention, a task chair includes a seat plate, a spine projecting upward from the seat plate, a carriage mounted for movement relative to the spine, and a pair of spaced-apart support arms supported by the carriage. The support arms flank the seat plate and are separated vertically from the seat plate. The task chair further includes first and second adjustment mechanisms coupled with the carriage and an adjustment element operatively coupled with the first and second adjustment mechanisms. The first adjustment mechanism is operative for moving the carriage relative to the spine to move the support arms up and down relative to the seat plate. The second adjustment mechanism is operative for moving the support arms laterally relative to the seat plate. The adjustment element is adapted to independently operate the first and the second adjustment mechanisms.
In another embodiment of the present invention, a task chair includes a support pedestal with a seat plate, a spine projecting upwardly from the seat plate, and a pair of spaced-apart support arms supported by the spine. The support arms flank the seat plate in a plane separated vertically from the seat plate. Each of the support arms includes a first arm portion coupled with the spine, a second arm portion, and a pivot joint rotatably coupling the first and second arm portions. The pivot joint allows the second arm portion to be inclined relative to the corresponding first arm portion for adjusting the inclination of the second arm portion relative to the seat plate.
In yet another embodiment of the present invention, a task chair includes a seat plate, a spine projecting upwardly from the seat plate, and a pair of spaced-apart support arms supported by the spine. The support arms, which flank the seat plate, are separated vertically from the seat plate. The task chair further includes a pair of pad slides each carrying an arm pad, and a pair of adjustment mechanisms each coupling a corresponding one of the pad slides with a corresponding one of the support arms. Each of the adjustment mechanisms has a first member mounted to the corresponding one of the support arms for movement in a first direction in a plane, and a second member mounted for rotation to the first member about an axis of rotation normal to the plane. The second member carries the corresponding one of the pad slides so that the pad slide rotates simultaneously with the second member.
The task chair includes a clean appearance achieved by replacing the traditional multiple arm pad adjustment knobs with a single adjustment arm pad adjustment knob. In addition, the clean appearance is promoted by locating the single adjustment knob at the rear of the task chair. A user seated in the task chair of the invention may easily manipulate medical equipment without concerns about power cables and/or vacuum lines snagging or winding about traditional adjustment knobs. The design of the task chair of the present invention is simplified as two directions of travel or degrees of freedom of the arm pads are adjusted by a single knob. The task chair further includes a system that allows the arm pads to be translated with at least one degree of linear freedom and rotated relative to the support arms to which they are attached. The task chair of the present invention is adaptable to a wide range of work place requirements while maintaining ergonomically correct comfort for a seated user. The task chair can adjust the support arms to accommodate a wide range of body shapes, physical sizes, and proportions of a seated chair user.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.
References herein to terms such as “vertical”, “horizontal”, etc. are made by way of example, and not by way of limitation, to establish a frame of reference. Terms, such as “anterior”, “posterior”, “on”, “above”, “below”, “under”, “upper”, “lower”, “over”, “beneath”, “right”, “left”, “rear”, and “front” are defined with respect to a person seated in the task chair. It is understood various other frames of reference may be employed for purposed of describing the task chair without departing from the spirit and scope of the invention.
With reference to
A plurality of legs 32 extends radially outward at a shallow angle from a base of vertical support pedestal 30 to define a rigid and stable chair support. Each leg 32 is fitted with a castor 34 so that the chair 10 can be rolled on the castors 34 about the work space environment. Flat floor pads, however, could replace the castors 34. Located within the vertical support pedestal 30 is a height-adjustable mechanism (not shown), such as a pneumatic cylinder, actuated by an actuation lever 36 for telescopically extending a center post relative to a center hub. A seated individual can operate actuation lever 36 for varying the length of the vertical support pedestal 30 and, hence, raising and lowering the height of the seat plate 26 and seat cushion 16 above the floor. A back frame (not shown), to which the back cushion 22 and lumbar pad 24 are attached, is carried vertically as the height of the seat plate 26 is changed.
Support arm 19 includes two arm portions 19a, 19b that are joined by an angled corner portion 19c. Similarly, support arm 21 includes two arm portions 21a, 21b that are also joined by an angled corner portion 21c. The angled corners 19c, 21c serve to reduce the space occupied by the support arms 19, 21. Arm portions 19a, 21a flank the seat plate 26 and are transversely spaced apart generally in an overlying plane spaced above the seat plate 26.
With reference to
The adjustment knob 38 is bi-directionally rotatable about a central axis 40, as indicated by double-headed arrow 28, and is inwardly/outwardly (e.g., anteriorly/posteriorly) movable in an axial direction parallel to the central axis 40. Turning the knob 38 in one angular sense or direction (e.g., clockwise as viewed from the posterior of task chair 10) raises the height of both of the support arms 19, 21 relative to the seat plate 26 and, hence, the height of the arm pads 18, 20 relative to the seat plate 26. Turning knob 38 in the opposite angular sense or direction (e.g., counterclockwise as viewed from the posterior of task chair 10) lowers the height of the support arms 19, 21 and associated arm pads 18, 20 relative to the seat cushion 16. The vertical adjustability of the support arms 19, 21 is indicated by double-headed arrows 31 on
The adjustment knob 38 is normally biased in an anterior direction so that varying the vertical position or height of the support arms 19, 21 relative to the seat plate 26 is the default mode of operation. However, the adjustment knob 38 is movable in an outward (i.e., posterior) direction along central axis 40 for engaging the components of the dual-axis arm adjustment system that adjust the separation between the support arm portions 19a, 21a. If the adjustment knob 38 is moved posteriorly and rotated, rotation in one angular direction or sense (e.g., clockwise) widens the distance between the support arm portions 19a, 21a, and rotation in the opposite angular direction or sense (e.g., counterclockwise) narrows the distance between support arm portions 19a, 21a, as indicated by double-headed arrows 33 in
With reference to
The yoke assembly 44 includes a bevel pinion 46, a bevel gear 48, a bevel yoke 50, a pair of yoke pins 51, 52, a support bracket 53, a yoke support 54, a knob shaft 56, and a pair of biasing members 57, 58 illustrated as coil compression springs. The bevel pinion 46 and bevel gear 48 operate as driven and driver gears, respectively, so that rotation of bevel gear 48 drives rotation of bevel pinion 46. Each of the biasing members 57, 58 is captured in a compressed condition between a head of one of the yoke pins 51, 52 and a centering recess defined in a side surface of yoke support 54. A threaded tip of each of the yoke pins 51, 52 is engaged with a corresponding one of a pair of threaded bolt holes defined in the bevel yoke 50. The support bracket 53 is joined with the H-shaped yoke support 54 by registering clearance openings defined in projecting arms of support bracket 53 with threaded openings defined on the top and bottom of each of the parallel side legs of the yoke support 54 and securing the support bracket 53 to the yoke support 54 with conventional fasteners.
Adjustment knob 38 is physically coupled with an exposed end 56a of knob shaft 56 to define an adjustment element for the dual-axis arm adjustment system. Bevel gear 48 and bevel yoke 50 are retained at an opposite end of the knob shaft 56 from the adjustment knob 38 by a pair of retaining clips 47, 49 engaged in corresponding circumferential grooves defined in knob shaft 56. A flat 64 on knob shaft 56 contacts a corresponding flat (not shown) defined inside the D-shaped hub opening of bevel gear 48, which operates as a key and keyway that constrain bevel gear 48 and knob shaft 56 to rotate with a common angular velocity. Gear teeth on the bevel gear 48 are meshed with gear teeth on the bevel pinion 46 when the adjustment knob 38 is in its normal position.
The adjustment knob 38 is biased in an anterior direction by the compressed biasing members 57, 58, which operate to maintain the adjustment knob 38 in its normal position unless a posterior-directed force sufficient to overcome the spring bias of biasing members 57, 58 is deliberately applied to the adjustment knob 38. A manual rotational force transferred from the adjustment knob 38 to the bevel gear 48 by rotation of the knob shaft 56, with the posterior-directed force applied, causes bevel gear 48 to drive rotation of bevel pinion 46. The biasing members 57, 58 may be replaced by other conventional spring biasing constructions. For example, a single coil spring may be positioned in a slot 67 defined in rear arm housing 75 with a coaxial relationship about the knob shaft 56 and compressed between coupling 76 and a portion of rear arm housing 75.
A closed-ended vertical slot 60 (
The yoke pins 51, 52, which pass through corresponding clearance holes defined in the yoke support 54, thread into the bevel yoke 50 for trapping the biasing members 57, 58 on the posterior face of the yoke support 54. The spring force applied by the biasing members 57, 58 resiliently biases the bevel gear 48 into mesh with the bevel pinion 46. The bevel yoke 50 supports the posterior end of the knob shaft 56 via the yoke pins 51, 52, and yoke support 54. The bevel yoke 50 also furnishes a bearing surface for the posterior face of the bevel gear 48. The bevel yoke 50 maintains its radial alignment with the yoke support 54 via the yoke pins 51, 52 and axially on the knob shaft 56. The posterior end of the knob shaft 56 rotates freely within a circular central opening 66 of the bevel yoke 50, which is coaxial with the D-shaped opening in the hub of the bevel gear 48. Hence, the position of bevel yoke 50 remains fixed relative to the knob shaft 56 as the knob shaft 56 rotates.
The support arms 19, 21 and respective arm pads 18, 20 are raised and lowered, along with yoke assembly 44, relative to the seat plate 26. As the yoke assembly 44 moves vertically, the back support member 12 moves relative to the spine 42 because the yoke assembly 44 and back support member 12 are both secured with the rear housing 73. The spine 42 is positioned partially in, or inset within, a vertical channel 41 defined in the back support member 12. Recessing the spine 42 in the vertical channel 41 allows the overall footprint of the task chair 10 to be minimized.
With reference to
Posterior movement of knob shaft 56 moves the depressions and projections of coupling 68 into a meshed mechanically-coupled driving engagement with the depressions and projections of coupling 71. When the couplings 68, 71 are meshed and locked, the relative separation between arm portions 19a, 21a of support arms 19, 21, respectively, is adjustable by rotation of the knob shaft 56. The lateral adjustment of the relative separation between arm portions 19a, 21a adjusts the distance between the arm pads 18, 20 (e.g., wider apart or closer together).
The posterior movement of the adjustment knob 38 and knob shaft 56 also moves bevel gear 48 in a posterior direction, which disengages bevel gear 48 from bevel pinion 46. As a result, the yoke assembly 44 and the height of the arm pads 18, 20 is undisturbed by rotation of the adjustment knob 38 when the adjustment knob 38 is displaced posteriorly. In other words, the yoke assembly 44 is uncoupled mechanically from rotation of the adjustment knob 38 and knob shaft 56 and, as a result, the height adjustment of the support arms 19, 21. The posterior movement of the adjustment knob 38 also further compresses the biasing members 57, 58 to provide a spring return when the axial force is removed from the adjustment knob 38. Contact between the bevel gear 48 and bevel pinion 46 acts as a stop for the spring return as the knob shaft 56 moves axially after the axial force is removed from the adjustment knob 38.
Arm portions 19b, 21b are positioned side-by-side inside assembled arm housings 73, 75. An arm rack 72 is fastened with conventional fasteners inside a recess of a closed contoured slot 77 (
When the adjustment knob 38 is maintained in the withdrawn posterior state and manually rotated, arm drive gear 70 concurrently moves arm racks 72, 74 in opposite directions as the meshed engagement between the arm racks 72, 74 and the arm drive gear 70 converts rotation of adjustment knob 38 into linear motion. The anti-parallel relative movement of arm portions 19b, 21b causes the arm portions 19a, 21a of support arms 19, 21 and, hence, arm pads 18, 20, to spread apart or move closer together depending on the direction of rotation. The depressions and projections of racks 72, 74 have the same pitch so that rotation of arm drive gear 70 simultaneously moves the arm portions 19b, 21b over equal linear distances and, consequently, changes the distance between arm portions 19a, 21a symmetrically relative to the seat plate 26.
The support arm portions 19a, 21a may be positioned in any one of a continuum of width states between maximum and minimum widths by applying an axial force against the spring bias of biasing members 57, 59 to activate the width-adjustment mechanism and then rotating the adjustment knob 38 in one direction or the other. When viewed from the posterior or rear of the task chair 10 and in one embodiment of the invention, a clockwise rotation of the adjustment knob 38, with knob 38 withdrawn axially in the posterior direction advances, the support arm portions 19a, 21a laterally away from each other, which widens the distance between the arm pads 18, 20. Counterclockwise rotation of the adjustment knob 38 moves the support arm portions 19a, 21a closer together, which narrows the separation between the arm pads 18, 20.
Arm drive gear 70 is secured to the D-shaped end 64 of knob shaft 56 by a D-shaped hub opening such that arm engagement gear 70 rotates with the same angular velocity as knob shaft 56. The knob shaft 56 projects through a clearance hub opening in a coupling 76, which is secured to knob shaft 56 between a retaining clip 78 and a collar 80 projecting radially outward from the knob shaft 56. The arm drive gear 70 is held in position by surface contact with the front and rear arm housings 73, 75, which keeps gear 70 centered and in a position suitable for engaging arm racks 72, 74. Posterior movement of knob shaft 56 moves the depressions and projections of coupling 68 into a meshed mechanically-coupled driving engagement with the depressions and projections of coupling 71, which couples the knob shaft 56 with arm drive gear 70.
When the knob shaft 56 is moved posteriorly by a pull force directed in a posterior direction, the depressions and projections of couplings 68 and 71 are engaged. When the posterior force is removed from the adjustment knob 38, the knob shaft 56 retracts in an anterior direction under the influence of the spring bias applied by the biasing members 57, 58. Couplings 68 and 71 are disengaged so that rotation of the knob shaft 56 does not rotate the arm drive gear 70. In the retracted position shown in
As a result, the width adjustment is independent of the height adjustment. The height-adjustment mechanism provided by yoke assembly 44 (
As best shown in
The front arm housing 73 is secured with conventional fasteners 86 (
The rear arm housing 75 also has an interior contour on an anterior surface (not shown but similar to the interior contour of the front arm housing visible in
Spine mount 14 pivotally joins the spine 42 to the seat plate 26, which serves as an anchor for the entire dual-axis arm system and connects it to the adjustable seat plate 26. The spine 42 and back assembly 13 may also be tilted forward and rearward relative to the seat plate 26 and fixed in position by a locking mechanism (not shown). The arm housing 75 includes flanges 87, 88 positioned on opposite sides of spine 42. The back support member 12 of back assembly 13 is secured with arm housing 75 with conventional fasteners 89 positioned with bushings in slotted openings defined in flanges 87, 88. The back assembly 13 travels vertically along with the support arms 19, 21 when the height of support arms 19, 21 is changed. When the fasteners 89 are loosened, the back assembly 13 is vertically movable over the extent of the slotted openings in flanges 87, 88, which permits the back assembly 13 to be moved vertically without changing the height of the support arms 19, 21. The spine 42 rides within the vertical channel 41 when the back support member 12 is moved up and down relative to the stationary seat plate 26 and arms 19, 21.
The adjustable slide attachment permits the lumbar pad 24 to be positioned relative to the support arms 19, 21 to accommodate different anatomies. For example, a tall male would have more distance from his lumbar relative to his arms at rest at his side, forearms parallel to the ground (or his lumbar relative to his elbows), than would a female with a smaller frame. This requires that the lumbar pad 24, which is attached to the back support member 12, be independently movable relative to the support arms 19, 21.
In addition to the dual-axis arm adjustment system described above, the task chair 10 further includes an arm pivot system and a multi-positional arm pad system that cooperate with the dual-axis arm adjustment system to create an effective support system that can be mounted to many existing available seat plates 26 for use with multiple different varieties of task chairs 10.
With reference to
Pivot joint 96 includes a pair of couplings 98, 100 each having circumferentially-arranged and confronting depressions and projections that are meshed. Coupling 100 is secured with the arm portion 19a of support arm 19 by conventional fasteners 99. Similarly, conventional fasteners 90 secure coupling 98 with arm extension 94. When the couplings 98, 100 are interrelated to mutually engage their confronting depression and projections, the inclination of the arm extension 94 is locked relative to the arm portion 19a and seat plate 26.
A lock knob 102 includes a threaded stud 103 that has a threaded engagement with an internally-threaded stub (not shown) of a pivot cover 104. This threaded engagement pivotally attaches arm extension 94 to the arm portion 19a. Lock knob 102 is adapted to be tightened to positively lock and secure the arm extension 94 against angular movement relative to the arm portion 19a by applying a clamping force that meshes the confronting projections of couplings 98, 100. This defines a latched condition in which the inclination of the arm extension 94 is fixed relative to arm portion 19a and the depressions and projections of couplings 98, 100 cannot slip relative to each other. The magnitude of the clamping force will vary depending, among other variables, on the user's adjustment of the lock knob 102.
When the lock knob 102 is loosened, the depressions and projections on couplings 98, 100 slip relative to each other when a rotational force effective to pivot arm extension 94 relative to the stationary arm portion 19a is applied to arm extension 94. In this unlatched condition, the arm extension 94 is rotatable relative to the arm portion 19a for adjusting the inclination of the arm extension 94. The pitch of the depressions and projections of couplings 98, 100 defines the angular increment over which the inclination may be changed.
A biasing member 106 applies a resilient bias that maintains pressure within the pivot joint 96, which aids the arm pivot adjustment process by keeping the couplings 98, 100 enmeshed and under pressure, so that the arm extension 94 does not lower when the lock knob 102 is loosened by an amount sufficient to permit slipping. Pressed into place on the inside of the arm extension 94 is a pivot limit pin 108 that projects into a curved slot 110 defined in arm extension 94. The arc length of the curved slot 100 limits the inclination range of the arm extension 94.
The arm pivot system permits a seated user to incline each of the arm pads 18, 20 individually to compensate for tilting of the back frame relative to the seat plate 26. The ability to change the inclination of the arm extensions 94, 95 permits the arm pads 18, 20 to remain in position with respect to a fixed plane, such as a work surface or the floor, after the back assembly 13 is tilted. Because the dual-axis arm system is affixed to the spine 42 and anchored to the seat plate 26 by spine mount 14, any adjustment of the tilt angle of the back frame will therefore tilt or adjust the pitch of the support arms 19, 21. If it is necessary to keep the arm pads 18, 20 parallel to the floor after adjusting the back frame angle, the inclination of the arm extensions 94, 95 may be readjusted to accomplish this. Of course, the arm pads 18, 20 may be inclined relative to the floor or the work surface while maintaining the angular orientation of the seat plate 26 fixed.
With reference to
Coupling mechanism 118 moves as an assembly relative to the arm extension 94 for adjusting the position of the arm pad 18 relative to the back cushion 22. The coupling mechanism 118 includes a mounting block or pivot plate 120 secured with conventional fasteners 121 to the arm extension 94 by a bearing block 122. The pivot plate 120 straddles the arm extension 94. The bearing block 122 rides within, and is guided by, a raceway or slot 124 defined near the free end of the arm extension 94. The length of the slot 124 determines the range of the linear travel of the coupling mechanism 118 and, hence, the range of motion of the supported arm pad 18 in the posterior/anterior direction. Attached with a conventional fastener 125 to the pivot plate 120 is a lock lever 126 that exerts pressure on an inside surface of the arm extension 94 when rotated into a locked position inline with the arm extension 94. The lock lever 126 incorporates a cam 128 that jams the travel of the arm extension 94 between the cam 128 and the pivot plate 120.
The coupling mechanism 118 further includes a pad slide 130 to which the pad 18 is mounted in a conventional manner, a lock knob lever 131, a lock knob 132 located beneath the pivot plate 120, a mounting bolt 134, and a friction or pressure plate 136, which collectively provide the lateral and rotational adjustments of the arm pad 18. The pressure plate 136 is positioned between the pivot plate 120 and the pad slide 130. Opposite side edges 135, 137 of the pressure plate 136 travel in confronting slots 138, 139 defined on the underside of the pad slide 130. The engagement between the side edges 135, 137 of pressure plate 136 and portions of the pivot plate 120 surrounding slots 138, 139 guides, regulates and locks rotation and sliding of the pad slide 130.
The pad slide 130 is rotatable about a pivot point defined by the mounting bolt 134 coupling the pressure plate 136 with the pivot plate 120. The lock knob bolt 131 projects downwardly through a curved slot 140 defined in the pressure plate 136. A threaded stud 142 on the lock knob lever 131 is engaged with an internally threaded hub of the lock knob 132. Contact between the shank of the threaded stud 142 and the opposite closed ends of curved slot 140 define rotation limits for the pad slide 130. The curvature of the curved slot 140 also defines the range of possible rotation angles for the pad 18. The pad slide 130 and the pressure plate 136 collectively rotate about the mounting bolt 134 within the defined rotation limits.
The lock knob 132, when tightened, applies a clamping force to the lock knob lever 131 that pulls the pad slide 130 and the pressure plate 136 toward the pivot plate 120. The clamping force applied by the lock knob 132 secures and locks all of the moving parts in a fashion that simultaneously inhibits lateral sliding and rotation of the arm pad 18. The magnitude of the clamping force will vary depending on the user's adjustment of the lock knob 132.
In use and with reference to
The pad slide 130 may also be rotated about an axis defined by mounting bolt 134 relative to the pivot plate 120. The rotational orientation of pad slide 130 is adjustable when lock knob 132 is loosened and is locked by the clamping force applied by the tightened lock knob 132. The coupling mechanism 118 may also be translated along the length of slot 124. A clamping force applied by the cam 128 of lock lever 126 is used to lock the position of the coupling mechanism 118 after this positional adjustment.
With reference to
While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants' general inventive concept. The scope of the invention itself should only be defined by the appended claims.
This application claims the benefit of U.S. Provisional Application No. 60/520,859 filed on Nov. 18, 2003, and the disclosure of which is hereby incorporated by reference herein in its entirety.
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1 321 193 | Jun 1973 | GB |
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Number | Date | Country | |
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20050104435 A1 | May 2005 | US |
Number | Date | Country | |
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60520859 | Nov 2003 | US |