US 3295092 A
Abstract available in
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Description (OCR text may contain errors)
Dec. 27, 1966 D. B. NEWMAN ETAL 3,295,092
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC RS 2 Sheets-Sheet Dec- 27, 1966 D. B. NEWMAN ETAL 3,295,092
COAXIAL PATCHBAY SYSTEM FOR ELECTRONIC COMPUTERS Filed Jan. 3l, 1964 2 Sheets-Sheet 2 @rates @l fine 3,295,092 COAXIAL PATCHBAY SYSTEM FR ELECTRONIC CMPUTERS Donald B. Newman, Long Branch, and Robert N. Griggs,
Brick Township, cean County, NJ., assignors to Computer Products Incorporated, Manasquan, NJ., a corporation of New .Iersey Filed Jan. 31, 1964, Ser. No. 341,680 Claims. (Cl. 339-18) This invention relates to electronic computers, and more particularly to the patchbay or programming systems of such computers.
The present invention applies to both analog and digital computers. However, for the sake of convenience, analog computers will be referred to in describing the invention.
An electronic analog computer includes a large number of computing elements, most of which are operational ampliers. In use, these computing elements must be interconnected according to a definite scheme depending upon the problem to which the computer is to be applied. The scheme of interconnections is referred to as the program of the computer, and the task of making the interconnections is called programming These connections between the computing elements must, of course, be made with absolute accuracy, and the interconnections must be of a temporary nature so that the computer can be reprogrammed as often as necessary to handle different problems.
Usually, the programming of electronic computers is accomplished by means of a patchbay or patchboard system located at the front of the computer. Such a system includes a patchbay comprising a plate, permanently mounted in the computer, having a plurality of electrical contact terminals projecting forwardly from it. These terminals are arranged in close proximity to one another in mutually insulated relationship, and are connected at their rearward ends to the computing elements of the computer. A problem board or patch panel is removably mounted in front of the patchbay. The patch panel is a plate having a large number of holes in it, each hole being Ialigned with one of the contact terminals projecting from the patchbay. Thus, a contact terminal inserted into one of the holes in the patch panel makes electrical contact with the corresponding terminal of the patchbay.
The interconnections between the computing elements are made by means of patchcords Each patchcord comprises la flexible electrical conductor having male contact terminals at both ends. These terminals are adapted to be accommodated by the holes in the patch panel in such a way that when they are inserted into the holes from the front face of the patch panel, they project from the rear face of the patch panel a distance sufficient to engage the forwardly projecting contacts of the patchbay. Therefore, when both terminals of a patchcord are operatively positioned within two holes in the patch panel, the patchcord serves to electrically interconnect the computing elements connected to the patchbay terminals engaged by the patchcord terminals.
In its operative position, the patch pane-l is parallel to and spaced a short distance in front of the patchbay. The patchbay contacts project into this space, and selected j contacts are engaged by the male patchcord terminals projecting into the space from the rear face of the patch panel. Although the patchbay contacts are insulated from one another, the portions of these contacts which extend into the space between the bay and patch panel are separated from each other by air only. Consequently, it has been found that during the operation of the computer there is an undesirable coupling effect between adjacent pairs of patchbay contacts. The term coupling effect as used herein refers to the circumstance that two adjacent patchbay contacts tends to take on the characteristics of the electrodes of a capacitor, with the air between them acting as the dielectric. Hence, when voltages are applied to these adjacent contacts, the voltage on one affects the Voltage on the other in the same way that the potential on one plate of a capacitor affects the potential on the other. The capacitive coupling effect on any patchbay contact tends to distort the output of the amplifier associated with that contact and hence adverse-ly affect the accuracy of the computer. l
The operational amplifiers of an analog computer operate over a working frequency range seldom exceeding a few hundred cycles per second. However, considerations of stability and dynamic error reduction require amplifier frequency response up to one megacycle. As is well known, the reactance of a capacitor depends upon the frequency of the voltage applied to it, the reactance increasing with increasing frequency. Therefore, the capacitive coupling effect mentioned above is not unduly disturbing during low frequency operation of the computer, but at high frequencies, it seriously affects the results produced by the computer.
It is, therefore, an object of the present invention to improve the accuracy of electronic computers operating at relatively high frequencies by eliminating the capacitive coupling elect between adjacent patchbay contacts.
Another potential source of inaccuracies in the output of electronic computers is the leakage of current between the contacts of the patchbay or those in the patch panel. Even though the patchbay contacts or the terminals in the patch panel Iare insulated from one another, since no material is a perfect insulator some small current leakage between contacts can occur. In the patchbay, such leakage between contacts is avoided without difficulty by employing a me-tal plate to carry the bay contacts. Thus, any current which may leak through the insulators separating the contacts from the metal plate is immediately conducted through the plate to ground, rather than to one of the other contacts. The problem of leakage between terminals in the patch panel can also be vavoided by fabricating the patch panel of metal. However, this presents an additional problem.
Usually, the programming operation is accomplished while the patch panel is removed from the computer. In other words, it is while the patch panel is out of its operative position on the computer that the terminals of the patchcords are inserted into the holes in the patch panel according to the particular programming scheme required to solve the particular problem presented. After the programming is completed, the patch panel is placed in its operative position so that the patchcord terminals engage their corresponding patchbay contacts. Nevertheless, it is often necessary to relocate one or more patchcord terminals after the patch panel has been operatively positioned. It will be appreciated that when one terminal of a patchcord is removed from the hole of the patch panel which it occupied, while the other terminal remains electrically connected to a patchbay Contact, it is almost impossible to insert it into another hole of the patch panel without touching the patch panel. Consequently, if the patch panel is made of metal, the voltage on the terminal of the patchcord being manipulated will be shortcircuited to ground.
Attempts have been made to overcome this shortcoming of metal patch panels by fabricating patch panels of an insulator material such as a suitable plastic. However, non-metallic patch panels present the problem mentioned above, viz., permitting leakage of current between terminals in the patch panel.
It is, therefore, another object of the present invention to improve the performance of electronic computers by providing a patchcord whose terminals are prevented from touching the patch panel during assembly of the patchcord with the patch panel thereby permitting a metallic patch panel to be employed without danger of shortcircuiting a voltage which may be present on the patchcord terminal.
It is a further object of the invention to eliminate the capacitive coupling effect between adjacent contacts in the space between the patchbay and patch panel by providing complete electrostatic shielding between adjacent contacts.
It is still another object of the invention to provide patchcords having female terminals, cooperable with male contacts within the patch panel, having outer insulation to prevent-contact between the terminall and the patch panel.
It is a general object of the invention to provide a patchbay system which is truly coaxial in nature.
These objects are achieved according to the present invention by providing within each hole in the patch panel a male contact element. The front end of this element is adapted to cooperate with the female terminals on the patchcords, and its rearward end is adapted to engage one of the patchbay contacts. Most important, each pair of engaged patchbay and patch panel contacts is completely surrounded by a metal sleeve for the entire distance between the patch panel and patchbay in order to electrostatically shield each pair of contacts from adjacent contacts. In addition, in order to insure good contact between each pair of patchbay and patch panel contacts, the patchbay contacts are advantageously spring biased toward the patch panel.
Other objects and advantages of the invention will be apparent from the following description in which reference is made to the accompanying drawings.
In the drawings:
FIG. l is a fragmentary perspective View, partially in section, of a patchbay system according to the present invention;
FIG. 2 is a fragmentary perspective view, partially in section, of the patchbay system;
FIG. 3 is a fragmentary perspective view, showing parts, partially in section, of the coaxial cable according to the present invention; and
FIG. 4 is a perspective view showing parts, partially broken away, of the patchcord according to the present invention.
The coaxial patchbay system chosen to illustrate the present invention comprises generally a patchbay 10, a patch panel 11, and a plurality of patchcords such as the patchcord 12. In the present example, the patchbay includes two metal plates permanently secured together in face-to-face relationship. For convenience, these plates will be referred to as the back plate 13 and the intermediate plate 14. Back plate 13 is provided with an arrangement of holes 15, and tted snugly within each hole is` a metallic tube 16. The tube is provided with longitudinal slots 17, to render it yieldable in a radial direction, and with annular ridges 1S. The tube is so sized that the outside diameter of the ridges 18 is slightly larger than the diameter of the holes 15 so that each tube ts tightly in its respective hole. At its rearward end, the tube 16 is formed with an enlargement 21 which limits the movement of the tube into the hole 15. Behind the enlargement 21 is a reduced portion 22 which ts closely around the `coaxial cable 23 with which it is associated, but it is slidable on the cable. In fact, the entire member 16, 21, 22 is slidable along the cable 23. The reason for this will be explained below.
Y The rearward end of the coaxial cable 23 is connected to one of the computing elements of the computer. The computing elements themselves, and the way in which they are connected to the cables 23 are well known and form no part of this invention; hence they are not illustrated. At its forward end, the cable 23 is permanently connected to a metallic female contact terminal or receptacle 24 (see FIG. 2) located within the tube 16. In FIG. 2, the receptacle is shown separate from the cable 23 and tube 16, for the sake of clarity. With reference to FIG. 3, there is shown surrounding the central conductor of the cable a layer of insulation 27, which in turn is surrounded by the outer conductor 30 of the cable. This outer conductor may be a metallic braided tube and is connected to ground whereby it serves t-o electrostatically shield the central conductor 25. Around the outer conductor 30 is another layer of insulation 31. A short tube 32 of insulation material surrounds the connection lbetween conductor 25 and receptacle 24.
The receptacle 24 is provided with longitudinal-slots 28 to render it yieldable outwardly when a male formation is inserted into it. This yieldability insures a tight t between the receptacle and the male formation, and also produces a wiping action between the male formation and the receptacle, which cleans them as they are assembled thus insuring good electrical contact between them. Surrounding the receptacle 24 is a bushing 33 of insulation material serving to insulate the receptacle from the metal back plate 13. The bushing 33 is permanently. associated with the receptacle 24, by means of the cooperation between the reduced region 34 around the receptacle and the inwardly projecting annular lip 35 formed at the rearward end of the bushing. At its forward end, the bushing 33 is formed with a collar 36 having an outside diameter larger than the diameter of the holes 15. The collar 36 prevents the bushing 33 and hence the receptacle 24 from sliding rearwardly through the hole 15. The outside diameter of the body of the bushing 33 is smaller than the diameter of the holes 15 in order to provide an annular space, clearly visible in FIG. 2, for accommodating the tube 16. It should be explained that in assembling the parts just described, the part comprising tube 16, enlargement 21, and portion 22 is rst slipped over the forward end of the coaxial cable 23 Then the cable is pushed through a hole 15 until its forward end projects forwardly of the front face of the plate 13. At this stage, a solder connection is made between the end 25 of the cable and the receptacle 24. The cable and receptacle are then pushed rearwardly until the collar 36 of the bushing 33 abuts the front face of the plate 13, and finally the part 16, 21, 22 is slipped forwardly along the cable and the tube 16 is pushed into the hole 15 until the enlargement 21 abuts the rear face of the plate 13.
The intermediate plate 14 of the patchbay is provided with a large number of holes 39 equal to the number of holes in the back plate 13, and arranged in locations corresponding to the arrangement of holes 15 in the back. plate. Snugly, but removably, fitted within each hole 39 is an insulator bushing 40 having a metal barrel 41 permanently mounted within it. A collar 38 formed on the forward end of bushing 40 limits the rearward movement of the bushing into the hole 39. The rearward end 42 of the barrel is provided with a pin-shaped male formation adapted to plug into, and thereby make electrical contact with the receptacle 24. For this reason, the
end 42 extends rearwardly past the end of the bushing 40.
The forward portion of the barrel 41 is hollow and slidably accommodates within it a metal plunger 43 having a contact head 44. A compression spring 45, within the barrel behind the plunger, urges the plunger in a forward direction. The bushing 40, barrel 41, plunger 43, and spring 45 comprise a unitary cartridge which may be removed from its respective hole 39, and replaced by another similar cartridge if desired, without disturbing the permanent connection between the receptacle 24 and cable 23.
The patch panel 11, which is removable from the computer, is shown in its -operative position in FIG. l. Like plates 13 and 14, panel 11 is a metal plate having a large number of holes 46 arranged in a pattern corresponding to the pattern of holes in the other two plates. As a consequence, when the patch panel 11 is operatively positioned, corresponding holes in the panel, intermediate plate, and back plate will be in alignment.
The rearward portion 47 of each hole 46 is counterbored to enlarge its diameter, and the forward portion of a cylindrical metal holder 50 is press fitted into, but removable from, the counterbored portion 47 of each hole. A bushing 51 of insulation material is held snugly within the holder 50, as may be seen clearly in FIG. 2, and a metal contact element 52 is permanently arranged wtihin the bushing 51. Each contact element 52 terminates at its rearward end in an enlarged contact head 53, adapted to engage the head 44 of plunger 43, and at its forward end in a pin-shaped male formation 54. Due to the positioning of the holder 50 in the rearward portion 47 of the hole 46, the male formation 54 at the forward end of the contact element 52 is deeply recessed within the hole. When the patch panel is placed in its operative position, which is to the right of the position shown in FIG. 2, it will be appreciated that the face of each contact head 53 engages the face of its respective contact head 44 and thereby pushes the respective plunger 43 rearwardly against the action of spring 45. The relatively large contact faces coupled with the yieldability of one of the faces insures good electrical contact between each pair of contacts 52 and 43.
Snugly fitted around each holder 50 is a metal sleeve 55. The forward end edge of each sleeve engages the rear face of the patch panel 11, and the length of the sleeve is such that when the patch panel is in its operative position the rearward end edge of the sleeve 55 engages the front face of the intermediate plate 14. For this purpose, the inside diameter of the sleeve is made large enough to accommodate the collar 38 of the bushing 40. It will be seen, therefore, that each pair of contacts 52, 43 between the patch panel and the intermediate plate of the patchbay is completely surrounded by its own metal shield thus completely electrostatically shielding the contacts from every other pair of contacts 52, 43.
The patchcords 12 of the present invention, as illustrated in FIG. 4 each comprise a short length of coaxial cable 56 having a special termination at each end. The termination includes a metallic female contact terminal or receptacle 57 permanently connected, as by soldering, to the central conductor 60 of the cable 56. The receptacle is adapted to receive, and thereby make electrical contact with, the male formation 54 of contact element 52. The receptacle 57 is provided with longitudinal slots 58 to render it yieldable outwardly when its slips -over the male formation 54. Surrounding the receptacle 57 is an insulator tube 61 which extends outwardly a little beyond the end of the receptacle so that the latter is slightly recessed within the insulator. A short plastic tube 62 surrounds the connection between the conductor 60 and receptacle 57, and a washer 63 of insulation material surrounds the tube 62. Surrounding the insulators 61 and 63 is a metallic member similar to the member 16, 21, 22 associated with the back plate 13. This member includes a tube 64 provided with longitudinal slots 65 to render it yieldable, and with annular ridges 66. The tube 64 is so sized that the Ioutside diameter of the ridges 66 is slightly larger than the diameter of the holes 46 so that each tube fits tightly in any one of the holes 46 of the patch panel. At its inner end, the tube 64 is formed with an enlargement 67 which limits the movement of the tube into the hole 46. However, the tube 64 is permitted to move far enough into the hole 46 t-o permit the receptacle 57 to slip over the male formation 54. Behind the enlargement 67 is a' reduced portion 70 which is permanently connected, as by soldering, to the outer braided conductor or shield 71 of the cable 56. A plastic jacket 72 surrounds the connection between the portion 70 and shield 71.
To program the computer, the patch panel 11 is rcmoved from its position at the front of the computer, and the terminations at both ends of each patchcord 12 are inserted into selected holes 46 in the patch panel as `shown in FIG. l. Although only one patchcord is shown in FIG. l, it is understood that many such cords are employed to establish a program. The receptacle 57 of each termination makes electrical contact with the contact element 52 within its respective hole; consequently, each patchcord electrically interconnects two of these contact elements. When the programming has been completed, the patch panel 11 is placed in its operative position wherein each contact element 52 engages one of the spring backed contacts 43. The contacts 43 are in turn electrically connected to the receptacles 24 in the back plate 13, each of the receptacles being connected through the cables 23 to one of the computing elements of the computer. It will be seen therefore, that each patchcord 12 serves to electrically interconnect two computing elements of the computer.
Most important, the output of each computing element as it is transmitted through its respective engaged pair of contacts 52, 43 will -be unaffected by the output of any other computing element since each pair of contacts 52, 43 is electrostatically shielded from the other pairs of contacts, in the space between the patch panel 11 and the patchbay, by one of the sleeve 55. All of the sleeves, of course, are at ground potential due to their contact with the patch panel 11 and plate 14. In addition, the rearward portion of each receptacle 24 and its connection to the central conductor of the cable 23 is electrostatically shielded from the other receptacles 24 by the member 16, 21, 22, which is at ground potential due to the contact between the tube 16 and the back plate 13. Similarly, the portion of the central conductor 60 of each patchcord which extends out of the recess 46 and is not surrounded by the braided shield 71 is shielded from the other similar portions of the other patchcords by the member 64, 67, 70, which is at ground potential due to the contact between tube 64 and patch panel 11. The remaining portions of the coaxial cables 23 and 56 have their central conductors shielded by the braided outer conductors 30 and 71, respectively. Consequently, it will be seen that the present invention provides a truly coaxial patchbay system in which there is no opportunity for the signals being carried by the central conductors to interfere with one another. Thus, the results produced by a computer incorporating the present invention are considerably more accurate than those produced by computers employing conventional patc-hbay systems, particularly when the computing elements are operating at relatively high frequencies.
Occasionally, after the patch panel 11 is in its operative position, it becomes necessary to relocate one or more of the patchcord terminations yfrom one hole 46 to another. By Virtue of the special terminations on the present patchcords, including the receptacle 57 recessed within the insulator 61, and t-he contacts 52 deeply recessed within each hole 46, it is impossible for the computer operator to touch the patch panel with the receptacle 57 and equally impossible to touch the contact 52 with the tube 64. Thus, there is no danger whatsoever of inadvertently s-hort-circuiting the voltage from any computing element to ground while relocating patchcord terminations after the patch panel is in its operative position.
It is a noteworthy feature of the invention that all the faces of contact heads 44 are completely exposed and therefore may readily be cleaned when the patch panel 11 is out of its operative position. Furthermore, as mentioned above, the entire cartridge including the bushing 40 may readily be removed and replaced when necessary, and similarly the entire assembly comprising the holder 50, bushing 51, and contact 52 may readily be removed and Ireplaced, when desired, as a field repair.
In addition to the patchcord 12, a patch plug 73 is illustrated in FIG. 1. The patch plug is similar in construction to the patchcord in that it comprises a coaxial cable 74 having terminations at each end identical to the terminations described above in connection with the patchcord 12. However, in the case of the patch plug 73 a single jacket 75 encloses both terminations. Consequently, the shields 76 of these terminations, and the receptacles within them, are rigidly held in parallel spaced-apart relation. In the present example, the terminals are so arranged that the shields 76 tit into two adjacent holes 46 in the patch panel. The patch plug therefore serves as a convenience during program-ming when the contacts |52 in two adjacent holes 46 are to be interconnected.
The invention has been shown and described in preferred form only, and by way of example, and many variations may be made in the invention which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are included in the appended claims.
What is claimed is:
1. In an electronic computer, a patchbay comprising a metal plate and a plurality of mutually insulated contacts insulated from said plate and projecting forwardly from said plate, said contacts being connected at their rearward ends to the computing elements of the computer, a patch panel in front of said patchbay and spaced from the latter, contacts within said patch panel engaging the contacts projecting from said patchbay, and a plurality of metal shields extending the entire distance between said panel and bay and surrounding each of said engaged pairs `of contacts in `order to completely shield said pairs of contacts from one another.
2. In an electronic computer, the elements defined in claim 1 wherein said patch panel is a metal plate.
3. In an electronic computer, a pat-chbay having a plurality of contacts projecting forwardly from it, a patch panel having front and rear faces, a plurality of holes in said panel extending between said faces, a metallic contact within ea-ch of said holes, the rearward end of each of said contacts being adapted to engage one of the contacts projecting from said patchbay when said patch panel is arranged in its operative position in front of said patchbay, a bushing of insulation material surrounding each of said contacts, and a tubular metal sleeve concentrically arranged with respect to each of said cont-acts and bushing extending rearwardly from the rear face of said patch panel, said sleeve being long enough to engage the front rface of said patchbay when said patch panel is arranged in its operative position, whereby each pair of engaged contacts will be completely shielded from every other pair.
4. In an electronic computer, the elements defined in claim 3 wherein said contacts projecting from said patchbay are yieldably biased toward said patch panel.
5. In an electronic computer, the elements dened in claim 4 wherein each of the contacts projecting from said patc'hbay has a fliat relatively vertical front face, and each of the contacts in said patch panel has a fiat relatively vertical rearward end to insure good electrical contact between each pair of engaged contacts.
6. In an electronic com-puter, the elements defined in claim 3 wherein said patch panel is a metal plate and the forward ends of said contacts within said patch panel have a male formation, and including a patchcord, each end of said patchcord being provided with a female contact element adapted -to be inserted into the holes in said patch panel and velectrically engage the contacts therein.
7. 'In an electronic computer, the elements defined in claim 6 including a bushing of insulation material surrounding each of said female contacts and extending outwardly at least as far as the leading edge of said contact to prevent said contact from accidentally engaging said metal patch panel when the contact is being inserted into one of said holes.
8. .In an electronic computer, the elements delined in claim 7 wherein said patchcord includes a coaxial cable having a central conductor and a tubular outer conductor concentric with and insulated from said central conductor, said central conductor Ibeing electrically connected to said female contacts at the ends ofl said patchcord, and a metal tubular shield electrically connected to said outer conductor surrounding the connection between said central conductor and each of said female contacts, said shield having a portion adapted to engage said metal patch panel when said female contact is inserted into one of said holes.
9. In an electronic computer, a patchbay comprising:
back and front metal plates arranged in adjacent parallel planes, a plurality of electric contact terminals mounted within said rear plate in insulated relation thereto, electrical conductors connecting said terminals to the computing elements of the computer, a plurality of apertures in said front plate, each of said apertures being aligned with one of the terminals in said back plate, a cartrid-ge snugly itted into each of said apertures, each cartridge including an outer bushing of insulating material, a rearwardly projecting metal terminal stationary with respect to said bushing, said metal terminal being cooperable with one of the terminals in said back plate, a forwardly projecting contact plunger slidable with respect to said lbushing along the axis of the latter, and resilient means urging said plunger forwardly; and
a patch panel carrying a plurality of contact elements in locations corresponding to the locations of said cartridges, the rearward ends of said contact elements engaging said plungers and moving them rearwardly against the action of said resilient means when said patch panel is placed in its operative position in front of the patchbay.
10. lIn an electronic computer, the elements dened in claim 9 wherein said bushings are removably mounted in said apertures whereby said cartridges may be removed and replaced without disturbing the connection between the terminals in said back plate and said electrical conductors.
References Cited by the Examiner UNITED STATES PATENTS 2,804,601 8/ 1957 Harthman et al. 339-143 FOREIGN PATENTS 87,754 3/ 1922 Austria.
EDWARD C. ALLEN, Primary Examiner. PATRICK AA. CLIFFORD, Examiner.