Patent Publication Number: US-3878753-A

Title: Harpsichord jacks

Description:
United States Patent Benson 1 1 Apr. 22, 1975 [54] HARPSICHORD JACKS 3.512.444 5/1970 Burton 84/258 [76] Inventor: Martin James Benson, 4107 N. FOREIGN PATENTS OR APPLICATIONS Spaulding BerWyn, 60618 763.505 12/1956 United Kingdom 84/258 695.831 8/1953 United Kingdom... 84/258 [221 1972 699.988 11/1953 United Kingdom 84/258 [21] Appl. No.: 245,426  
  Primary ExaminerRichard B. Wilkinson U S Cl 84/258 Assistant liruminer-John F. Gonzales [5]] Int. Cl. Gl0c 1/06 [58] Field of Search 84/258. 320 [57] F Q A harpsichord ack usmg a smgle l1ghtwe1ght part-a 5 References Cited combination spring and p1ectrum-for the plucking of UNITED STATES PATENTS the harpsichord string. Greater reliability is obtained a a 7 than from conventional jacks. The improved jack uti- 11221332 #1335 52325531:f&#39;&#34;&#34;i111iiijijiiiiizai i guiding Pins for smooth&#34; 2.808.754 10/1957 Taylor 84/258 4 2 Claims, 6 Drawing Figures PATENTEDAPRZZIQZS FIG. 5 (PRIOR ART) FIG. 6 I (PRIOR ART) 2:5  
 HARPSICHORD .IACKS DESCRIPTION:  
  The invention relates to improvements in harpsichord jacks. In a harpsichord. the musical tones are produced through the action of harpsichord jacks, which ride up and down on the ends of the keys. and cause the strings to be plucked. Harpsichords have long suffered from various problems. which can be attributed to the poor design of conventional jacks.  
  One of these is lack of repeatability&#34;-repeatability being a measure of the&#39;efficiency with which a harpsichord action can produce the same note twice in succession. For example. if a note can be sounded. then sounded again after a very short interval of time. the harpsichord action is said to possess good repeatability.  
  Another problem is hanging jacks.&#34; or hangers. A hunger is the name given to a jack that does not descend after it has produced a musical note.  
  Another problem of conventional jacks is sloppy guide action.  
  The nature and cause of. and remedy for these defects will be more apparent after the conventional and improved jacks are described in greater detail later in this application.  
  It is an object of the present invention to enhance repeatability ofthe harpsichord action. and to reduce the frequency of hangers. A further object is to provide a jack with a superior guiding system. Yet another object is to provide a jack which can be easily and cheaply manufactured.  
 FIG. I shows a front view of the present invention;  
  FIG. 2 shows a partial back view of the present invention:  
  FIGS. 3 and 4 show different constructions of the combination spring and plectrum of the present invention: and  
  FIGS. 5 and 6 show the construction of a conventional jack.  
 The improved jack operates in the following manner:  
  When key 1 is struck. jack 2 rises. guided at the upper end by pins 3 and 4 riding in upper guide 5. and at the lower end by endpin 6. in jackguide 7. One pin can be used instead of pins 3 and 4. but in that case. it. or the endpin 6. must have a flat side. or a slot. or some such means for preventing the jack turning about its longitudinal axis.  
  On the upstroke of the jack. string 8 is plucked by part 9. and a musical tone is produced. Part 9. a combination spring and plectrum. is the most important feature of the present invention. and is therefore shown in greater detail in FIG. 3.  
  Part 9 consists of a thin strip of flexible material with springlike qualities. such as acetal or nylon. which is bent at an angle of approximately 90. The part is fastened at its lower end to the back of the jack by suitable means. The upper. horizontal portion of part 9 is a plectrum section. The string is actually plucked by the tip of this section. while the back end ofthe section is supported by the body of the jack at point A. shown in FIG. 3. and FIG. 2. The lower. vertical section acts as a spring.  
  After the string is plucked. the jack continues to rise until it hits the bottom of guide 5. Part 10 is a shock absorbing pad of felt or rubber to cushion this collision of jack against upper guide. As an alternative. the upper guide pins can be surrounded by coil springs. for braking action. and for returning the jack more quickly than would gravity alone.  
  When key 1 is released. the jack descends. When the tip of the plectrum section of part 9 strikes the string on the downstroke. the upper section of part 9 is thrown back away from the string; but once clear ofthe string. it is returned to its original position through the action of the spring section. The jack comes to rest on the key. with the damper ll stopping the vibration of the string. 9  
  FIG. 4 shows an alternative construction of part 9, in which the plectrum section is comprised of leather. which material has been extensively used for harpsichord plectra.  
  In general. the improved jack functions in nearly the same manner as a conventional jack. but there are two essential differences. as follows:  
  I. In a conventional jack (see FIG. 5. which is a partial view of a jack typical of the vast majority of jacks in use today). the plectrum. part 12, is set into the top of a tongue. part 13. which pivots on the pivot pin. part 14. On the downstroke of the jack. the end of the plectrum strikes the string. and the top of the tongue is thrown backwards. clear of the string. the tongue pivoting on the pivot pin. After the plectrum clears the string. the tongue is thrown back to its original position by a spring (FIG. 6. part 15). which is fastened to the jack body and pushes against the back of the tongue. 2. A conventional jack is guided at its upper end by the jack body passing through a rectangular guide hole.  
  To return to the causes of hangers and lack of repeatability in conventional jacks. the first of these is the tongue pivot pin. If this is too tight. the tongue will not pivot backwards on the downstroke. and the plectrum will not clear the string. giving us a hanging jack. The improved jack. not having a pivot pin. does not suffer from this ailment.  
  Another source of trouble is the upper guiding system on the conventional jack. .Iack bodies are generally of molded plastic. or wood. and. therefore. dimensional accuracy and stability are far from perfect. The guideholes. being rectangular. are difficult to fabricate with any great degree ofdimensional accuracy. also. The result is that the guide holes are often too tight for the jack. producing hangers. or too loose. which could af fect repeatability. or cause overplucking of the string. The use of upper guide pins. as in the present invention. should eliminate such problems.  
  The tongue spring is a conventional jack can also cause malfunctions. For example. if the spring is too strong. the tongue will not pivot enough on the downstroke of the jack. and the plectrum will not clear the string. and once again a hanger results. However. if the spring is too weak. the tongue may not return all the way to its original. forward position against the jack after the plectrum clears the string. and if the same key is quickly struck again. the plectrum may not even reach the string. and no note is produced. The spring. then. can be neither too strong. nor too weak. and the range of possible spring tensions is rather narrow. as is known by those skilled in the art.  
  The present invention further improves on the conventional jack in that the combination spring and plectrum. being much lighter than the tongue-plectrumspring assembly of the conventional jack. does not require as strong a spring. since the lightweight part will accelerate much faster back into its original position abter clearing the string. Because of this faster acceleration. repeatability is assured. Also. with a weaker spring. the jack is not so likely to get hung up on the plectrum. since since this part will clear the string more easily. Thus. it can be seen that spring tension is not so critical on the improved jack.  
  Another advantage of the present invention. ease of manufacture. should be self-evident.  
  Having thus described the invention. what is claimed as new is:  
  l. A string plucking mechanism for a harpsichord having a frame which supports a keyboard and a plurality of strings. the plucking mechanism comprising a jack having an opening therein and being mounted in the frame. means for guiding the jack for up and down movement in response to the actuation of a key. and plectrum means disposed in said opening for plucking a string. wherein said plectrum means comprises an L- shaped. flexible member having a first leg extending through said opening from the side of the jack nearest the string to the opposite side of the jack. and a second leg extending along the said opposite side of the jack and having a first end attached to said first leg and a second end secured to said opposite side of the jack.  
  2. in a harpsichord jack. uide means comprising a lower guide pin secured to the bottom of said jack and a lower guide having a hole through which the lower guide pin passes. a first and second upper guide pin secured to the top of said jack and an upper guide having two holes one through which passes the first upper guide pin and the other through which passes the second upper guide pin.