US 6,290,609 · Granted 2001-09-18
The Adjustable Weight Golf Club That Shifts Your Sweet Spot
Imagine a golf club head where you can swap out internal weights like battery compartments to change how the club feels and performs. This patent covers a design that lets golfers fine-tune where the club's center of gravity sits, making it easier to hit solid shots from different spots on the club face.
The plain-English version
What it protects
The claim covers an iron golf club head with removable or adjustable vertical balance weights positioned at specific locations on the rear face — heavier weights near the toe and heel edges, lighter weights in the center. What's protected here is the combination of these interchangeable weights in different configurations that allow a golfer or manufacturer to alter the club's weight distribution, moment of inertia, and center-of-gravity location without redesigning the entire head.
Why it matters
This patent addresses a real problem in golf equipment: most clubs come fixed, but golfers have different swing speeds, skill levels, and preferences. By making the weight system modular and adjustable, the design lets a single club head accommodate multiple playing styles and skill levels, potentially reducing the number of clubs a golfer needs to buy or making one club adaptable as a player improves. It also enlarges the 'sweet spot' — the optimal hitting zone — by positioning the center of gravity deeper in the head.
Real-world use
When a golfer swaps out different weights in their club head at the pro shop before a tournament, they're using the exact engineering this patent locks down — adjusting how the club performs for their particular swing.
Original USPTO abstract
An iron golf club which enables a further fine adjustment of the weight balance, moment of inertia and the like of a head. Four vertical balance weights 11 A, 11 B, 11 C and 11 D are disposed on different positions on a rear face 10 , respectively. The first and fourth vertical balance weights 11 A and 11 D of larger specific gravity are provided on a toe or heel side of the rear face 10 A. In the center of the rear face 10 A are provided the second and third vertical balance weights 11 B and 11 C of smaller specific gravity. Through the combination of the balance weights 11 A, 11 B, 11 C and 11 D of various shapes and specific gravity, the weight balance of the head 1 can be freely adjusted. Also, the position of the center of gravity of the head 1 can be positioned backwards, thus enlarging the sweet area. In addition, as the denser balance weights 11 A and 11 D are provided near the toe 7 or the heel 6 , the toe 7 and heel 6 of the head 1 can be weighted.
Patent details
- Publication number
- US 6,290,609
- Filing date
- 1999-09-20
- Grant date
- 2001-09-18
- Assignee
- K.K. Endo Seisakusho
- Inventor(s)
- TAKEDA HITOSHI
- CPC class
- A63B53/047
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