Music – Instruments – Stringed
Reexamination Certificate
2000-03-06
2001-10-09
Hsich, Shih-Yung (Department: 2837)
Music
Instruments
Stringed
C084S299000, C084S307000
Reexamination Certificate
active
06300550
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention pertains to tremolos, and more particularly to simplified tremolos that replace original equipment.
2. Description of the Prior Art.
It has long been known to equip guitars and other stringed musical instruments with tremolos. The tremolos enable the instrument player to change the tension in the strings when desired and thereby change the tuning of the strings.
Tremolos typically have at least three places at which relative movement of the various components occur. The first is a pivot arrangement at which the entire tremolo pivots relative to the instrument body. A common pivot arrangement is a pair of knife edges on a tremolo bridge that pivot on grooved posts that are embedded in the instrument body. Typical examples of prior knife edge and post designs are shown in U.S. Pat. Nos. 4,549,461 and 5,708,225.
A second place of relative movement between tremolo components is at intonation blocks on the bridge. The intonation blocks are moveable relative to the bridge and the instrument strings to set the effective span of the strings. Once the intonation blocks are locked in place when the tremolo is initially set up, they rarely have to be moved again. Typical prior tremolo intonation blocks can be seen in U.S. Pat. Nos. 5,481,955 and 5,808,216.
A third place of relative movement between tremolo parts is at fine tuners. The fine tuners are designed to change the tension in the instrument strings by small amounts and thereby vary the string tonal qualities. Prior fine tuners are shown in U.S. Pat. Nos. 5,431,079 and 5,460,072.
For various reasons, the prior tremolos are not entirely satisfactory. As one reason, the knife edges of the prior tremolos tend to wear with usage. As they wear, their pivoting action on the instrument posts becomes unreliable and inconsistent. However, replacing the knife edges of prior tremolos is not possible without replacing the entire tremolo. Accordingly, it is a major inconvenience and expense to overcome the problems associated with worn knife edges.
Another deficiency of prior tremolos concerns the fine tuners. In the tremolo of the U.S. Pat. No. 5,431,079 patent, for example, there is a first sharp bend in the strings at their contacts with the fine tuners. There is another sharp bend in the strings at their contact points with the intonation blocks. The two sharp bends tend to weaken the strings, and the strings usually break at one or other of the bends. Further, prior fine tuners were designed with flat ends that contacted the strings. The strings easily and frequently slipped off the ends of the fine tuners as they were being adjusted, and it was a chore to return the strings back into contact with the fine tuners.
Prior tremolos were also infamous for the large number of small and expensive parts associated with the intonation blocks and fine tuners. Assembling the numerous small parts added further to the cost of the tremolos. U.S. Pat. Nos. 5,109,745 and 5,477,765 show large numbers of small parts assembled into an expensive tremolo.
Because of the problems associated with prior tremolos, it is frequently necessary to replace them. However, because of their expense, instrument owners were hesitant to replace unsatisfactory tremolos with new ones, which were prone to the same problems. In the past, different model tremolos were not designed to be interchangeable with one another on an instrument. That is, after a particular tremolo model was installed in an instrument, replacing that tremolo with a different and less expensive model was invariably a difficult and even unworkable task.
Thus, a need exists for a practical way to replace prior tremolos with an improved model.
SUMMARY OF THE INVENTION
In accordance with the present invention, a simplified retrofit tremolo is provided that easily replaces an unsatisfactory existing tremolo on a stringed instrument. This is accomplished by designing the retrofit tremolo to be interchangeable with and superior to the existing tremolo.
The retrofit tremolo combines a string anchoring block, intonation block supports, and a spring plate into one T-shaped bridge. The construction of the retrofit tremolo is thus greatly simplified compared to the tremolos it replaces.
The bridge has front and back ends, opposite sides, and a generally flat bottom surface. The spring plate depends from the bridge bottom surface. The block is adjacent the bridge back end. The intonation block supports are part of a bridge support plate that extends from the block to the bridge front end.
In a guitar, the frets on the neck define aligned arcs of large radius. To match the arcs, the bridge support plate is formed with a series of steps. The steps on the bridge support plate are designed such that the strings passing over the intonation blocks lie along the same arc as the instrument frets.
The strings make a shallow bend between the intonation blocks and pockets on the back end of the bridge block. The pockets receive the ball ends of the strings. The strings pass through respective slits in the block. There is ample clearance between the strings and the bottoms of the block slits. Thumb screws of fine tuners engage tapped holes in the block associated with the respective slits. The ample clearance in the slits under the fine tuners assures that a wide range of pitch change is available by turning the thumb screws. The thickness of the bridge support plate provides the further advantage of furnishing a large bearing area for a tremolo arm.
At the bridge front end near the sides are a pair of knife edges. The knife edges are designed to contact and pivot relative to posts embedded in the instrument.
Further in accordance with the present invention, worn knife edges are removable from the bridge. For that purpose, the knife edges are on inserts that are held tightly by friction in respective recesses at the bridge front end. Although the inserts are held tightly in the bridge, they nevertheless are removable when desired by pulling them with a pliers or similar tool.
It is a feature of the invention that the fine tuners have grooved tips that engage the strings. The tips are rotatable about the longitudinal axes of the thumb screws. The tip grooves prevent the strings from slipping off the ends of the fine tuners when the thumb screws are rotated to change the string pitch. To aid in guiding a string into a tip groove during setup, the free ends of the tips are rounded in planes perpendicular to the grooves.
The spring plate is designed to enable the springs of an original tremolo to be used with the retrofit tremolo. A person merely disconnects the existing springs from the spring plate of the original tremolo. The springs are not removed from the instrument. The springs fit perfectly onto the retrofit tremolo.
To prevent binding or catching of the strings on the intonation blocks, the strings pass over small rollers incorporated into the intonation blocks. In keeping with the purpose of making the retrofit tremolo as simple as possible, the roller of each intonation block is supported by a pin between two side walls of the intonation block. A base on the intonation block is slotted to receive a screw that locks the intonation block to the bridge at a location that sets the desired span of the associated string.
The method and apparatus of the invention, using components that match existing tremolo-related components on a stringed instrument, thus enables a person to retrofit the instrument with a superior but less expensive tremolo. The retrofit tremolo is economical, simple in construction, and very easy to install and set up, even though it contains relatively few components.
Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.
REFERENCES:
patent: 4549460 (1985-10-01), Gressett, Jr. et al.
patent: 5088374 (1992-02-01), Saijo
patent: 5173565 (1992-12-01), Gunn
patent: 5413019 (1995-05-01), Blanda, Jr.
patent: 6015945 (2000-01-01),
Cayen Donald
Hsich Shih-yung
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