Interconnection system for a biological waveform simulator device

An interconnection system for an electronic biological waveform simulator device utilized for testing the operability of a biological waveform sensing machine such as a vectorcardiogram machine. The system includes a housing with a major surface and a circuit board within the housing containing electrical circuitry for generating output signals simulating a biological waveform. A plate affixed to the major surface of the housing includes an undercut slot adapted to receive a disc-shaped electrode commonly used with the sensing machine. A connector disposed in the slot electrically connects the electrode, when engaged in the slot, with the circuitry. Preferably, the system includes a second connector projecting from an upper surface of the plate for receiving jacks utilized with disposable electrodes. In the preferred embodiment, the first and second connectors are electrically connected together so as to provide alternate signal paths for the simulated waveform from the electrical circuitry.

CROSS REFERENCE TO RELATED APPLICATION 
This application is related to copending application, U.S. Ser. No. 93,085, 
entitled "Vectorcardiogram Simulator", filed concurrently herewith and 
having the same assignee as the present invention. 
BACKGROUND OF THE INVENTION 
This invention relates to biological waveform simulator devices. More 
particularly, it involves an interconnection system for such devices. 
Various biological waveform simulators have been introduced into the 
marketplace for testing the operability of medical devices such as 
electrocardiogram and blood pressure monitors. Examples of such devices 
are disclosed and claimed in copending U.S. patent application Ser. No. 
882,357, entitled "Complex Analog Signal Generator", filed Mar. 1, 1978, 
(now U.S. Pat. No. 4,204,261) and U.S. patent application Ser. No. 
938,430, entitled "Electrocardiographic and Blood Pressure Waveform 
Simulator Device", filed Aug. 31, 1978, (now U.S. Pat. No. 4,205,386). 
These patents are hereby incorporated by reference. 
These simulator devices have provided extremely satisfactory results and 
have enjoyed increasing popularity in the industry. In general, these 
devices generate substantially the same type of waveforms that would 
normally be supplied by a live patient or at least of sufficient quality 
to ascertain whether the sensing machine will work properly under normal 
operating conditions. The present invention is particularly concerned with 
an interconnection system such that the same cables and/or electrodes 
which are utilized for monitoring a live patient can also be plugged 
directly into the simulator device without further modification. This 
invention finds particular utility with Frank-type electrodes utilized in 
vectorcardiography. 
SUMMARY OF THE INVENTION 
The advantages and features of the present invention are accomplished by 
way of an interconnection system for a simulator device which includes a 
housing having a major surface. A circuit board within the housing 
contains electrical circuitry for generating an output signal simulating a 
biological waveform. A plate affixed to the major surface of the housing 
includes an undercut slot adapted to receive a disc-shaped electrode from 
the sensing machine. First connector means disposed in the slot 
electrically connect the electrode, when engaged in the slot, with the 
circuitry. Thus, the same electrode that is used in normal patient 
monitoring use may be removably inserted into the slot to couple the 
simulated waveforms to the sensing machine for testing its operability. 
According to another feature of this invention the interconnection system 
includes second connector means projecting from the plate. The second 
connector means may be alternately used for coupling jacks utilized with 
disposable electrodes into the simulator. The first and second connectors 
are electrically connected together as to provide alternate signal paths 
for the output signal from the electrical circuitry. 
Preferably, the plate is made of a transparent material such that an 
indicator card may be sandwiched between the housing and the plate for 
providing labels for the first and second connectors.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, the simulator device 10 of the present invention 
is shown as it would be utilized in typical use with a vectorcardiogram 
machine 12. Vectorcardiogram machines are well known in the art. 
Vectorcardiography is the art of analyzing the electrical activity within 
the heart by obtaining electrocardiograms along three axes at right angles 
to one another and displaying any two of these ECG's as a vector display 
on an X--Y oscilloscope. Vectorcardiogram machine 12 may be such as the 
one manufactured by Instruments for Cardiac Research Inc. of Syracuse, 
N.Y. 
Vectorcardiogram machines generally utilize one of two types of electrodes, 
the disc electrodes 26 which are shown in FIGS. 1 and 2 or the snap type 
disposable electrodes 14 shown in FIG. 4. The disposable electrodes 14 
generally include a flexible electrically conductive pad 16. Pad 16 is 
electrically connected to the VCG machine 12 by way of a connector 18 
having a male portion 20 which engages a corresponding female receptacle 
22 in jack 24. 
As shown in FIGS. 1-2, the disc-shaped electrodes 26, which are not 
disposable, include a bell shaped cover 28 with an upper dome and lower 
lip portions 30 and mouth portions 32. This disc-shaped electrode includes 
a circular electrically conductive contact 34 within the confines of mouth 
32. VCG machine 12 generally includes eight such electrodes 26 which 
correspond to RA, LA, C, E, M, LL, H, and RL inputs to a Frank attenuation 
and compensation network within the VCG machine 12. 
Simulator device 10 includes a generally rectangular housing 38 having an 
upper major flat surface 40. A printed circuit board 42 is mounted within 
housing 38 in a conventional manner. Circuit board 42 includes electrical 
circuitry schematically designated by the box 44 for generating an output 
signal simulating a biological waveform. The details of circuitry 44 are 
not particularly important to the present invention but it may take the 
form as disclosed in the above-incorporated by referenced applications or 
as that disclosed in copending U.S. patent application Ser. No. 93,085, 
entitled "Vectorcardiogram Simulator" by Schultz, Jr. et al, concurrently 
filed herewith and assigned to the same assignee as the present invention. 
Face plate 46 is affixed to major surface 40 of housing 38. Preferably, 
plate 46 is made of a transparent plastic material. Plate 46 includes a 
plurality of undercut slots 48 spaced about its periphery. In the 
preferred embodiment, there are eight such slots which are specifically 
adapted to receive the disc shaped electrodes 26. Slots 48 each include a 
U-shaped bottom portion 50 which is open ended towards the periphery of 
plate 46. A generally conforming peripheral ledge 52 extends radially 
inwardly and is spaced from the bottom portion 50 a sufficient distance to 
permit the lip portion 30 of electrode 26 to be interposed between bottom 
portion 50 and the lower surface of ledge 52. 
Each slot 48 includes a resilient connector 54 which projects upwardly 
beyond slot bottom portion 50 as can be seen most clearly in FIG. 2. 
Preferably, connector 54 includes an outer sleeve 56 containing a spring 
(not shown) in lower portions thereof which provides upward bias to piston 
58. Sleeve 56 includes a flange about its upper surface for mounting onto 
surface 40 of housing 38. Piston 58 terminates in a rounded head 60. By 
inspection of FIG. 2, it can be seen that the rounded head of connector 54 
permits the mouth 32 of electrode 26 to glide over head 60 while 
temporarily depressing it until electrode 26 is fully engaged in slot 48. 
When so engaged, the upward resiliency of piston 58 presses against 
electrode contact 34, with the ledge 52 abutting against lip portion 30 to 
thereby sandwich the electrode 26 in slot 48 so that good electrical 
connection is made. 
According to another feature of this invention, device 10 includes a second 
set of connectors 62. Connectors 62 take the form of a threaded shaft 64, 
a transverse collar 66, and a ball male projection 68 for engaging female 
portion 22 of disposable electrode jack 24. Shaft 64 passes through 
openings in circuit board 42 and is secured thereto by way of nut 70. 
There is one such connector 62 for each of the connectors 54. Connectors 
54 and 62 are electrically connected together so as to provide alternate 
signal paths for the output signal from the electrical circuitry 44. The 
sleeves 56 of connectors 54 pass through cutaway portions in the periphery 
of circuit board 42. The bottom portion of sleeves 56 are coupled by way 
of wires 72 in a ribbon cable to a dual in line package (DIP) male header 
or connector block 74. In FIG. 2, connector block 74 is shown disengaged 
with a female connector block 76. When engaged, connector blocks 74 and 76 
provide an interconnection system by which electrical output signals from 
electrical circuitry 44 are coupled to connectors 54, the electrical 
circuitry 44 being connected to female receptacles (not shown) in female 
connector block 76. Each of these receptacles or terminals are 
electrically connected to corresponding pairs of connectors 54 and 62. The 
electrical path to connectors 54 is by way of pins 78 in connector block 
74 and through their respective wires 72 in the cable. The receptacles are 
coupled to connectors 62 by way of conductors 80 on the printed circuit 
board 42 which make electrical connections to shaft 64 by way of nut 70. 
Therefore, according to one aspect of this invention, the interconnection 
system provides a means by which either disposable electrode jacks 24 or 
disc-shaped electrodes 26 may be utilized. 
A card 82 contains illustrations and printing for labeling each pair of 
connectors 54 and 62. Since each pair provides an alternate connection for 
VCG machine 12, only one label for each pair is provided. In the 
particular example shown in FIG. 1, connectors 62 are disposed directly 
inboard of their corresponding disc electrode receiving slots 48. Card 82 
contains appropriate Frank lead system electrode designations. Beginning 
from the lower most pair of connectors shown in FIG. 1 and moving 
clockwise, they are labeled C, RL, RA, M, H, E, LA, and LL, respectively. 
From the foregoing specification, it can now be realized that the present 
invention provides a unique method of providing reliable electrical 
contact to disc electrodes which are normally utilized in a 
vectorcardiogram machine. Thus, the simulator device 10 can be plugged in 
directly without modifying the sensing cables utilized in 
vectorcardiography. Moreover, it is a feature of this invention that 
provision is made for accepting disposable electrode jacks as well as disc 
electrodes. Accordingly, the simulator device becomes universally adapted 
to test the operability of a variety of different types of machines. It 
should be noted that while this invention finds particular utility in 
connection with a vectorcardiogram machine, it may be utilized for a wide 
variety of different biological waveform sensing machines utilizing an 
equally wide variety of disc-type electrodes. 
Therefore, while this invention has been described in connected with 
particular examples thereof, no limitation is intended thereby except as 
defined in the appended claims.