Improvements in Pianofortes.
Year: 1896

page_text: Date of Application, 15th May, 1896
LL
Sch 1907
Accented 10th Apr
1897
PROVISIONAL SPECIFICATION.
Improvements in Pianofortes.
I, HERBERT JOHN BRINSMEAD of 7, Fellows Road, South Hampstead
London N.W., Pianoforte Manufacturer, do hereby declare the nature of this
invention to be as follows:-
My invention relates to improvements in the sounding boards and actions of
pianofortes and it has for its object, as regards the sound-board, to produce a tone of
more equal quality, greater volume, and sonorousness and, as regards the action, to
avoid inequality of weight of the touch in the case of what are known as under
damper actions.
The first part of the invention relates to the transverse bars applied to the back or
underside of the sound-board and consists in substituting for the ordinary bars which
are of solid rectangular section, longitudinally grooved or channelled bars, the bars
baving two or more webs separated by intermediate grooves. By reason of their
sectional form and the disposition of the material the improved bars are more efficient
and cover the area of the sounding board more equally than ordinary bars without
increasing the weight or encumbering the sounding board which is consequently
capable of vibrating more freely and of producing a tone of greater volume and
sonority.
The second part of the invention relates to under-damper actions wherein the
weight or resistance of the dampers is removed from the keys when the dampers are
raised by the forte pedal, the result of removing this resistance being consequently
to lighten the touch which is therefore rendered unequal in weight as the pedal is
raised and lowered. To obviate this irregularity in the weight of the touch I
provide what may be termed an artificial resistance to compensate for the removal of
that of the dampers and which is thrown into action when the dampers are raised
by the pedal. This resistance is applied by springs carrying clothed blocks which
by the movement of the forte pedal in lifting the dampers are brought into position
to oppose to the key action a resistance equal to that of the dampers. The springs
are preferably mounted on a rail adapted to be thrown into acting position by the
forte pedal stick and the clothed blocks carried by the springs are thereby brought
into the path of the action levers or of any other suitable part of the action.
Dated this 15th day of May 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
Improvements in Pianofortes.
Hampstead,
1, HERBERT JOHN BRINSMEAD of 7, Fellows Road, South
Pianoforte Manufacturer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
My invention relates first to an improvement in the sounding board of a pianoforte

page_text: having for object to produce a tone of more equal quality, greater volume, and
sonorousness, the improvement being applicable both to the horizontal and also to the
upright form of instrument.
The invention relates secondly to an improvement in the action of an upright
pianoforte having for object to avoid inequality of weight of the touch in the case of
what is known as an under damper action.
The invention is illustrated in the accompanying drawings forming part of this
specification wherein
Figure 1 is an underside view of the sounding board of a horizontal pianoforte and
Figures 2, 3, 4, are cross-sections of different forms of bars the last mentioned
figures being drawn full size.
Figure 5 is an end elevation of an under damper check action for an upright
pianoforte provided with touch-compensating springs which are shewn in operative
position in Figure 6.
The first part of the invention illustrated in Figures 1, 2, 3, 4, relates to the
transverse bars A applied to the underside or back of the sound-board B and the
improvement consists in substituting for the ordinary bars which are of solid
rectangular section bars of longitudinally grooved or cbannelled form such as shewn
in cross section in Figures 2, 3, 4, the bars having two or more webs & separated by
an intermediate groove or grooves c. By reason of their sectional form and the
disposition of the material the improved bars are lighter and more efficient since
being broader than solid bars of the same weight and stiffness they will be closer
together and will therefore cover the area of the sounding board more equally than
the same number of ordinary bars without increasing the weight or encumbering
the sounding board which is consequently capable of vibrating more freely and of
producing a tone of greater volume and sonority. Furthermore the greater breadth
of the surface b' which is glued to the sound-board not only ensures a better glueing
but enables the glued joint to more effectually withstand the effect of warm and
moist climates. As will be observed the precise sectional form of the bar is
susceptible of modification and the webs b may be either parallel sided with
intermediate rectangular grooves or they may be V-shaped, the essential feature
being breadth of the surface b¹ combined with lightness and greater depth and
relative narrowness of the individual webs, which compensate by their depth for the
removal of the material at the groove or grooves c. The bars are planed or moulded
out of the solid by preference and sufficient thickness is left at the base to ensure
the distribution of the transverse stiffness due to the webs over the whole breadth of
the bar.
The second part of the invention relates to what are known as under-damper check
actions wherein the resistance due to the damper spring is removed from the key
when the dampers are raised off the strings by the depression of the forte pedal, the
result of removing this resistance being to lighten the touch which is therefore
rendered lighter and heavier as the pedal is depressed and raised. To obviate this
irregularity in the weight of the touch I provide what may be termed an artificial
resistance to compensate for the removal of that of the dampers, which resistance is
thrown into action by the depression of the pedal. This resistance is applied by
springs d (one for each key) carrying clothed blocks d' which by the moveinent of
the forte pedal in lifting the dampers are brought into position to oppose to the key
action a resistance equal to that previously opposed by the damper. The springs d
are preferably fixed by their heel ends to a rail D carried by arms mounted on fixed
centres e suitably supported at intervals the rail D being raised by a lug f on the
forte pedal stick F when the pedal is depressed so as to bring the blocks d' carried
by the springs d into position to oppose the depression of the rear ends of the action
levers G, as shewn in Figure 6, and so compensate for the diminished resistance
due to the lower ends of the damper levers 1 being moved out of range of the arms g
of the action levers when by the litting of the pedal stick F the rod H carried by
a bell crank lever and passing in front of the lower ends of all the damper levers 1
is caused to move the damper levers out of range of the arms g.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Constructing the bars of pianoforte sounding boards of grooved or channelled
or equivalent section with a broad glueing face and narrow webs substantially as and
for the purpose specified.
2. The combination, with an under damper upright action of touch compensation
springs substantially as described adapted to be brought into position to oppose the
key action when the resistance of the damper springs is removed as specified."
Dated this 15th day of February 1897.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.