US 5,184,828 · Granted 1993-02-09
The Three-Layer Golf Ball That Changed the Game
Imagine a golf ball like a jawbreaker candy — hard shell on the outside, squishy center, and a special middle layer that controls exactly how bouncy it is. This patent describes how to engineer each layer with precise hardness levels so the ball travels farther and spins just right.
The plain-English version
What it protects
The claim covers a golf ball made from three solid pieces (not wound string): an inner core 23-35 mm wide, an outer layer surrounding it, and a protective cover. What makes it protected is the specific hardness recipe — the core gets progressively harder toward its edge, peaks at the boundary between core and outer layer, then softens again. The exact hardness ranges at each depth are what competitors can't copy without infringing.
Why it matters
Golf ball design is a precision sport. Before three-piece solid designs became standard, most balls used tightly wound rubber thread, which was harder to control and manufacture consistently. This patent represents the shift toward engineered, layered cores that let manufacturers dial in exactly how far a ball will fly and how much it will spin — a huge competitive advantage in a sport where milliseconds and inches matter.
Real-world use
When you hit a golf ball off the tee, the compression and spring-back you feel comes from this layered hardness structure working together to store and release energy efficiently.
Original USPTO abstract
A non-wound three-piece golf ball which comprises an inner core, an outer layer and a cover, the inner core having a diameter of 23-35 mm and a hardness (Shore D) of 30-62, the outer layer having a diameter of 36-41 mm and a hardness (Shore D) of 30-56, the golf ball having a hardness (Shore D) 46-62 at the outer site in the inner core, which is 11.5-17.5 mm apart from the center of the ball. The golf ball has a maximum hardness (Shore D) in the range of 46-62 at the outer site of the inner core which is located at the interface between the inner core 1 and the outer layer 2 of the golf ball and the hardness then decreases both inwardly and outwardly.
Patent details
- Publication number
- US 5,184,828
- Filing date
- 1991-05-14
- Grant date
- 1993-02-09
- Assignee
- Ilya Co. Ltd.
- Inventor(s)
- KIM; MOON K., HWANG; IN H.
- CPC class
- A63B37/0003
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