U.S. patent number 3,864,823 [Application Number 05/431,802] was granted by the patent office on 1975-02-11 for method of making a buzzer structure.
This patent grant is currently assigned to General Signal Corporation. Invention is credited to Charles Berns.
United States Patent |
3,864,823 |
Berns |
February 11, 1975 |
METHOD OF MAKING A BUZZER STRUCTURE
Abstract
A buzzer structure, of the type comprising a housing having a
coil unit therein and an armature mounted for vibratory movement
adjacent the coil unit, includes an integral portion of the housing
which is bent inwardly into engagement with the coil unit to fix
the spacing between the coil unit and housing, thereby to determine
the dimensions of the gap between the coil unit and armature. The
spacing and gap dimensions are adjusted, after the buzzer elements
are assembled, by energizing the coil unit, applying a force to a
portion of the housing to progressively deform it to displace the
coil unit in engagement therewith, and monitoring the magnitude of
current flow through the coil unit while simultaneously monitoring
the sound output of the buzzer to determine when a proper operating
point has been reached, at which time the progressive deformation
of the housing and displacement of the coil unit is immediately
terminated.
Inventors: |
Berns; Charles (New Milford,
CT) |
Assignee: |
General Signal Corporation
(Rochester, NY)
|
Family
ID: |
23713484 |
Appl.
No.: |
05/431,802 |
Filed: |
January 8, 1974 |
Current U.S.
Class: |
29/602.1; 29/593;
335/96; 335/252; 335/278; 340/396.1; 340/392.3 |
Current CPC
Class: |
G10K
9/22 (20130101); G10K 9/15 (20130101); Y10T
29/49004 (20150115); Y10T 29/4902 (20150115) |
Current International
Class: |
G10K
9/15 (20060101); G10K 9/00 (20060101); G10K
9/22 (20060101); H01f 007/06 () |
Field of
Search: |
;29/602,593,594
;340/400,401,402 ;335/96,252,278 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hall; Carl E.
Attorney, Agent or Firm: Pollock, Philpitt & Vande
Sande
Claims
Having thus described my invention I claim:
1. The method of optimally and permanently adjusting the relative
positions of the elements of a nonoperative buzzer to render said
buzzer operative, said buzzer being of the type comprising a
housing having an energizable electric coil mounted therein and
also having an armature mounted therein for movement adjacent said
coil but initially spaced from said coil by a gap the dimensions of
which are sufficiently large to prevent said armature from being
attracted to said coil if said coil were energized, said method
comprising the steps of energizing said coil, progressively
deforming a portion of said housing adjacent said coil, on a side
of said coil remote from said armature, to cause the deformed
portion of said housing to engage said coil and to displace said
energized coil toward said armature thereby to progressively reduce
the dimensions of said gap, monitoring the operating condition of
said buzzer as said progressive deformation step proceeds, and
terminating said progressive deformation step and the resultant
displacement of said coil when said monitoring step determines that
said buzzer has commenced to operate.
2. The method of claim 1 wherein said energizing step comprises
energizing said coil at a potential less than its rated
potential.
3. The method of claim 1 wherein said progressive deformation step
comprises cutting a pair of spaced slots in a predetermined portion
of said housing to define the deformable portion of said housing
between said slots, and then applying a force between said slots
directed from the exterior toward the interior of said housing to
progressively deform said portion into the interior of said
housing.
4. The method of claim 1 wherein said monitoring step comprises
monitoring the magnitude of current flowing through said energized
coil.
5. The method of claim 1 wherein said monitoring step comprises
monitoring the sonic output of said buzzer.
6. The method of claim 1 wherein said monitoring step comprising
monitoring the magnitude of current flow through said energized
coil to determine when there is a significant reduction in said
magnitude of current flow while simultaneously monitoring the sonic
output of said buzzer to determine when there is a significant
increase in said sonic output.
7. The method of claim 1 wherein said progressive deformation step
includes the step of energizing a motor operative to move a tool in
forcible engagement with said housing portion, the terminating of
said deformation step comprising the step of reversing the polarity
of energization of said motor to reverse the direction of movement
of said tool.
Description
BACKGROUND OF THE INVENTION
Various buzzer structure, adapted to be energized by AC and/or DC,
are in themselves well known. Such buzzer structures typically
comprise a coil unit associated with a vibratory armature mounted
adjacent thereto. In the case of AC operation, the armature may
constitute a permanent magnet adapted to be successively attracted
to and repelled by the changing polarity poles produced in the AC
energized coil unit or, if the armature has a comparatively small
mass, the armature may comprise a strip of magnetic metal mounted
on a spring and adapted to be successively attracted to one end of
the coil unit at a frequency dependent upon the frequency of
energization, e.g., a 60-cycle coil energization causes armature
vibration at 120 cycles per second. In the case of DC operation,
the armature is further associated with a contact pair which
controls the energization circuit of the coil in well known fashion
to successively make and break said energization circuit and
thereby cause vibratory motion of the armature. The present
invention is concerned, in general, with buzzers of these various
different types.
In buzzer assemblies of the general types described above, proper
operation of the buzzer depends, inter alia, on proper positioning
of the coil unit and armature relative to one another, i.e., if the
gap between these elements is too large the armature will not be
attracted to the coil unit when the coil unit is energized. It is
possible, of course, to calculate precisely where the parts should
be positioned relative to one another in dependence upon the
parameters of the coil unit and armature and the operating
conditions which are desired, and to carefully engineer and
assemble the buzzer based upon such calculations. However an
approach of this type, and the resultant precision in manufacture
and assembly which it contemplates, is not economically justifiable
when it is desired to provide a simple, comparatively inexpensive
buzzer assembly; and in this latter case, the usual practice has
been to mount the coil unit and armature in general proximity to
one another within a housing, and then to manually adjust the
positions of these elements relative to one another while observing
the operating state of the buzzer thereby to establish the
operating point of the buzzer. More particularly, it has been the
practice heretofore to provide an adjustable set screw in the
buzzer housing positioned to bear upon a portion of the coil unit
and, with the coil energized but with the gap between the coil unit
and armature too large to cause the armature to be attracted to the
energized coil unit, to turn the set screw thereby to force the
coil unit toward the armature until the gap has been reduced
sufficiently to cause the buzzer to commence its operation, at
which time the set screw is locked into place.
The prior art adjustment technique discussed above has a number of
disadvantages. It requires, of course, the provision of a set screw
and associated tapped hole in the housing which tend to increase
the cost of the buzzer somewhat; and while the cost of these items
is comparatively small, it may become significant in the case of an
extremely inexpensive buzzer construction. In addition, the
adjustment procedure, requiring the turning down of the set screw
and the subsequent locking thereof into place, is comparatively
slow and does not lend itself to an automated procedure. Moreover,
the adjustment may not be as permanent as desired since there is
always the possibility that an improperly locked screw may shake
loose, in which event the dimensions of the gap between the coil
unit and armature can change to render the buzzer inoperative.
The present invention obviates all of these disadvantages of the
prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, the housing of a buzzer
unit of the type described above is modified to eliminate the
tapped hole and associated set screw and, instead, is formed with a
pair of generally parallel, comparatively short slots therein which
define, between the slots, a housing portion which is depressible
or deformable toward the interior of the housing. This deformable
portion of the housing is located adjacent the mounting position of
the coil unit so that, when a force is applied thereto from the
exterior of the housing, the deformable portion is bent into a
substantially V-shaped configuration which protrudes toward the
interior of the housing in engagement with the coil unit to
displace the coil unit. Deformation of the deformable housing
portion thereby performs the adjustment function of the prior art
set screw arrangement described previously, but does so in a far
more economical, efficient, and otherwise generally improved
fashion. Adjustment is accomplished simply by applying a force to
the deformable portion of the housing, thereby to bend said
deformable portion toward the housing interior in progressively
greater increments until the desired buzzer operating point is
achieved, at which time the applied bending force is removed to
leave the coil unit locked at its proper position by the deformed
housing portion in engagement therewith. By this arrangement and
procedure, the set screw and its tapped hole previously employed
are eliminated and the manufacturing cost of the buzzer is
accordingly reduced, proper adjustment is accomplished much more
quickly and the adjustment is far more permanent than in the case
of a set screw.
The improved buzzer arrangement of the present invention lends
itself, moreover, to an automated adjustment procedure. More
particularly, the adjustment can be effected by a selectively
energizable motor which operates, through an appropriate gear box,
to advance a tool which is in engagement with the deformable
portion of the buzzer housing while the operating condition of the
buzzer is monitored. In a preferred embodiment of the invention,
the buzzer coil unit is energized at a voltage which is, for
example, approximately 30 percent below its nominal or rated
voltage, during the adjustment procedure; and the operating
condition of the buzzer is monitored by sensing the magnitude of
current flowing through the coil unit (the magnitude is
comparatively high until the buzzer starts operating, at which time
it drops to a significantly lower value) and while simultaneously
monitoring the sound output of the buzzer (which is initially
silent and which starts to buzz as the adjustment proceeds). The
mechanism employed to effect this monitoring procedure senses the
current and sonic parameters simultaneously, and preferably
includes means for adjusting the thresholds at which the current
drop and sonic output increase are detected; and when the
characteristic changes in both parameters are sensed, a logic
circuit operates to reverse the energization to the motor thereby
to immediately reverse the direction of rotation of the motor to
return the depressing tool to its zero position.
The adjustment procedure is accordingly accomplished simply by
aligning the tool with the depressible housing portion, thereafter
energizing the motor, and permitting the motor to run first in its
forward direction until the proper operating point of the buzzer
has been achieved, at which time the motor drive immediately and
automatically reverses to terminate the adjustment procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing construction, operation, and advantages of the
present invention will become more readily apparent from the
subsequent description and accompanying drawings in which:
FIG. 1 is a top view of a buzzer housing constructed in accordance
with the present invention;
FIG. 2 is a vertical cross sectional view of the buzzer of FIG. 1,
incorporating the adjustment structure of the present
invention;
FIG. 2A depicts a portion of the structure shown in FIG. 2, but
with the prior art set screw adjustment incorporated therein;
and
FIG. 3 is a schematic diagram of an automatic adjustment mechanism
used in conjunction with a buzzer of the type shown in FIG. 2, to
practice the automatic adjustment procedure of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring initially to FIGS. 1 and 2, it will be seen that the
buzzer of the present invention (which, except for the adjustment
feature to be described hereinafter, is a prior art, commercially
available structure) comprises a housing 10 having a cup-shaped
upper portion 10a and an opposing lower closure portion 10b
mechanically joined to one another at 10c and supporting
therebetween, at its periphery, a disc-shaped diaphragm 11 adapted
to produce a sonic output via an opening 10d in the lower closure
portion. The diaphragm 11 is in turn associated with a buzzer
mechanism, disposed within cup-shaped housing portion 10a,
comprising an armature 12 which is mounted adjacent a coil unit 13
adapted to be electrically energized via lead 14 to effect
vibratory motion of armature 12 to cause said armature to
repetitively strike a a stud 15 affixed to the center of diaphragm
11.
Armature 12 takes the form of a strip of magnetic material having
its free end disposed adjacent the core 13a of coil unit 13. The
other end of armature 12 is attached to a spring 16 which is in
turn secured to an L-shaped bracket 17 which is affixed to the
upper side (as viewed in FIGS. 2 and 2A) of coil unit 13. The
entire buzzer unit, which is thus of unitary construction, is
mounted on the base of cup-shaped housing portion 10a by means of a
rivet 18, but with armature 12 and core 13a of coil unit 13 being
electrically isolated from housing 10 by means of an intervening
insulator 19.
Assuming for the moment that the gap between armature 12 and core
13a is of proper size, when coil unit 13 is energized with AC
applied across leads 14, it causes armature 12 to be successively
attracted to core 13a against the force of spring 16, and thus
causes the armature 12 to vibrate between core 13a and stud 15, at
a repetition rate which is twice the applied frequency, i.e., with
60 hz coil energization employed, the buzzer will sound at 120 hz.
Alternatively, the buzzer may be cause to operate with DC
energization by grounding housing 10 thereby to ground diaphragm 11
and its stud 15, by positioning armature 12 to normally engage stud
15, and by applying DC energization to coil 13 through the contact
set provided by stud 15 and armature 12 in accordance with known DC
buzzer techniques.
When the buzzer unit, comprising interconnected coil unit 13 and
its associated armature 12, are initially assembled, it is
conventional in the art to provide a gap between the coil unit and
armature which is too large to permit the buzzer to operate and
thereafter to reduce the size of this gap by an adjustment
procedure, effected after the buzzer has been assembled, which
adjusts the buzzer to its proper operating point. More
particularly, it has been standard practice to mount the buzzer
unit within cup-shaped portion 10a of housing 10 with the upper
side of its coil unit initially being in close proximity to and in
substantially flush engagement with, the interior of the base of
housing portion 10a, and to provide said base with an adjustment
set screw 20 (see FIG. 2A) disposed within a tapped hole in said
base for engagement with the flush mounted buzzer unit at a
position comparatively widely spaced from its mounting rivet 18.
With coil unit 13 energized, e.g., at a voltage approximately 30
percent below nominal or rated voltage, screw 20 is turned down to
cause energized coil 13 to be moved progressively away from the
interior of the base of housing portion 10a about mounting rivet
18, thereby to successively reduce the gap between coil unit 13 and
armature 12; and when the buzzer starts to operate, set screw 20 is
locked into place e.g., by means of a lock nut 21 or by the
application of an appropriate cement compound thereto. This
conventional adjustment procedure requires that the buzzer housing
be provided with a set screw and an associated tapped hole, further
requires the provision of means for locking the set screw at its
adjusted position and involves a comparatively time consuming
manual adjustment procedure, all of which necessarily increase the
cost of the buzzer unit. Yet the resultant adjustment may be less
permanent than desired since there is always the possibility that,
in use, the set screw may work free or become unlocked, causing the
buzzer to go out of adjustment and become inoperative. The present
invention obviates all of these disadvantages of the prior art.
In accordance with the present invention, instead of using a set
screw such as 20, the base of cup-shaped housing portion 10a is
provided with a pair of comparatively short, parallel, spaced slots
25 (see FIG. 1) which define therebetween a deformable housing
portion 26 located at generally the same position in the overall
assembly as was previously associated with set screw 20. The
resultant somewhat weakened portion of the housing is reinforced by
forming the base of cup-shaped portion 10a with outwardly
protruding reinforcing ribs 27 in partially surrounding relation to
deformable portion 26.
Deformable portion 26 is located in comparatively widely spaced
relation to mounting rivet 18 at a position directly adjacent the
coil unit 13. When it is desired to adjust the buzzer to its
operating point a force applied to the deformable housing portion
26, from the exterior of the housing directed toward the interior
of the housing, deforms said portion 26 into the generally V-shaped
configuration shown in FIG. 2, and as this deforming force
continues to be applied, the depth "h" of the V-shaped depression
increases to successively displace coil unit 13 away from the
interior of the base of housing portion 10a thereby to reduce the
gap between coil unit 13 and armature 12. When the depth "h" of the
depression becomes sufficiently large to set the buzzer unit to its
desired operating point, the deforming force is removed from
housing portion 26 to leave the coil unit 13 at its then adjusted
position relative to armature 12 and, without any subsequent
locking procedure, the component parts of the buzzer assembly
remain locked in proper position relative to one another by the
permanently depressed housing portion 26 during subsequent use of
the buzzer mechanism.
The user of a deformable housing portion 26 simplifies the
construction of the housing structure itself, reduces its cost by
eliminating the set screw and associated tapped hole previously
considered necessary, reduces the time needed to adjust the buzzer
to its proper operating point, and produces a more permanent
adjustment. In addition, the modification of the present invention
adapts the entire structure to an automatic adjustment procedure
which has not been possible heretofore. This additional aspect of
the present invention will now be described with reference to FIG.
3.
As shown in FIG. 3, a buzzer 30, constructed as shown in FIGS. 1
and 2, may be located at an adjustment station with its deformable
housing portion 26 underlying a depressing tool 31. Tool 31 may in
turn be moved in translation by a gearing mechanism 32 which is
driven by a reversible motor 33, and motor 33 is in turn energized
through a reversing circuit 34 from a power supply 35 having an
on-off switch 36. The coil leads of buzzer unit 30 are connected to
terminals 37a, 37b which energizes the coil at a potential
approximately 30 percent below nominal or rated voltage from source
38, and which further functions to insert an adjustable current
sensor 39 in series with the buzzer coil.
A sonic sensor 40 is disposed in facing relation to the sound
emitting orifice 10d of the buzzer to determine when buzzer 30
commences producing a sound output. Sonic sensor 40 is preferably
arranged to provide an adjustable threshold, so that it can be set
for an optimum db output corresponding to the optimum adjustment
point of buzzer 30, and adjustment of current sensor 39 similarly
permits sensor 39 to be set to a current level which also
represents an optimum operating condition. The outputs of the
sensor 39 and 40 are coupled as two inputs to an AND gate 41 the
output of which is coupled to reversing circuit 34.
Assuming for the moment that depressing tool 31 is in its "zero"
position, and that the coil of buzzer 30 is energized from source
38, closure of switch 36 energizes motor 33 through reversing
circuit 34 to cause the motor to commence operating in a forward
direction, thereby to move tool 31, via gear box 32, in a direction
toward the interior of the buzzer housing. This in turn causes
deformable housing portion 26 to be depressed by successively
greater amounts, and simultaneously causes displacement of the coil
unit 13 within the buzzer toward the proper operating point of the
buzzer. When the proper operating point has been reached, as
monitored by the optimum db output sensed by sensor 40 and by a
significant reduction in coil current to a desired optimum value as
sensed by sensor 39, the signals simultaneously applied to gate 41
cause the gate output to activate reversing circuit 34 e.g., to
energize a relay in said circuit. This reverses the polarity of
energization of motor 33 and causes it to immediately withdraw
depressing tool 31 toward its zero position. Thus once the
automatic adjustment mechanism of FIG. 3 is set into operation, the
buzzer is progressively adjusted toward its operating point; and
once the optimum point of adjustment is achieved, as monitored by
the current flowing through the buzzer coil and by the sound output
of the buzzer, all further adjustment is immediately terminated and
the system is returned to its starting point.
While I have thus described preferred embodiments of the present
invention, many variations will be apparent to those skilled in the
art. It must therefore be understood that the foregoing description
is intended to be illustrative only and not limitative of the
present invention and all such variations and modifications as are
in accord with the principles described are meant to fall within
the scope of the appended claims.
* * * * *