Plug-in circuit cartridge with electrostatic charge protection

A plug-in cartridge designed to mate with an external system via a connector having a plurality of external mating receptacles, and one or more external actuator pins, for engaging the cartridge. The cartridge encloses a printed circuit board with terminals arranged to receive an electrical circuit (e.g., an integrated circuit) susceptible to damage by excessive electrostatic charge. The circuit board includes a plurality of metallic contact areas conductively connected to respective terminals, extending external to the cartridge, and configured to engage the mating receptacles of the connector. The cartridge also includes a protection device comprising a plurality of conductive fingers formed from a common conductive element. The device is arranged such that, when the cartridge and connector are disengaged, the fingers contact associated ones of the contact areas whereby the contact areas and therefore the circuit terminals are connected in common (i.e., shorted) to preclude circuit damage due to electrostatic charge. When the cartridge is mated to the connector, the actuator pins contact the device to lift the fingers off the contact areas, thereby permitting the electrical circuit to operate in expected fashion.

This invention concerns a plug-in cartridge enclosing an electrical circuit 
such as may be used for programming the operation of an electrical system 
with which it is designed to operate. More specifically, the invention 
relates to such a cartridge including means for preventing circuit damage 
due to excessive electrostatic charge when being handled. 
A cartridge of this type can be used, for example, in so-called "video 
games" apparatus. As is known, such apparatus is operatively associated 
with a visual display device such as kinescope of a television receiver, 
and includes a manually operated control unit for use by one or more 
operators, or "players" . A control unit of this type is programmed to 
operate according to one or more "game" formats. One-piece cartridges 
containing electrical control circuitry and designed to plug into the 
control unit are a convenient means by which the control unit can be 
programmed to respond to various game formats as selected by the operator. 
The programming cartridge and the control unit often include integrated 
circuit devices (e.g., CMOS devices) which can be damaged by excessive 
electrostatic charge, particularly when the cartridge is being connected 
and disconnected from the control unit. 
It is therefore desirable to protect the circuit devices within the 
cartridge from electrostatic charge when the cartridge is being 
disconnected from the control unit. It is also desirable to protect the 
circuit devices within both the cartridge and the control unit when the 
cartridge is being connected to the control unit. 
Cartridge apparatus according to the present invention includes a rigid 
member having means for mounting thereon an electrical circuit susceptible 
to damage from excessive electrostatic charge. A plurality of conductive 
contact areas associated with the mounting means is disposed along an edge 
of the rigid member. Also included is a charge protection device 
comprising a plurality of conductive elements formed from a common 
conductive member having a contact region. The rigid member with the 
electrical circuit and the protection device are enclosed and secured by a 
housing assembly. The housing assembly is configured to define an aperture 
through which the contact areas are externally exposed. The housing 
assembly also defines a receptacle configured to receive an external 
actuator device, when present. The conductive elements engage the contact 
areas in the absence of the actuator device. The contact region of the 
protection device is conductively engaged by the actuator device when 
received by the receptacle, to thereby cause the conductive elements to 
disengage from the contact areas.

In FIG. 1, a cartridge 10 fabricated of plastic or similar material 
encloses a printed circuit board 12 having a plurality of exposed 
elongated conductive contacts 13 disposed thereon. Each of these contacts 
is connected to a corresponding circuit terminal (i.e., of an integrated 
circuit) which is arranged on board 12 internal to cartridge 10. A 
protection device 15 fabricated from a single piece of metallic spring 
material (e.g., stainless steel) is mounted on circuit board 12 within 
cartridge 10. A portion of protection device 15 consists of a plurality of 
elongated conductive fingers 18 corresponding to the number of contacts 
13. 
A connector 20 includes a plurality of terminals 24 corresponding to the 
number of contacts 13 of cartridge 10. Each terminal has an associated 
mating receptacle (not shown) on the opposite side of connector 20 (i.e., 
facing contacts 13) for receiving the corresponding contact of cartridge 
10 when the cartridge and connector are mated. Connector 20 also includes 
a pair of metallic actuator pins 22a and 22b for engaging a portion of 
protection device 15 within cartridge 10, when the cartridge 10 and 
connector 20 are mated via receptacles 28a and 28b, as will be discussed. 
The actuator pins contact a metallized area 30, which in this case serves 
as an area of ground potential when connector 20 is mounted on a suitable 
control unit (not shown). Pins 22a and 22b also assist to align connector 
20 and cartridge 10 when being mated. 
When connector 20 is mounted on a suitable control unit, terminals 24 of 
connector 20 are coupled to appropriate circuits within the control unit. 
These circuits are designed to cooperate with the circuits contained 
within cartridge 10 to allow the control unit, and any associated 
apparatus, to operate in desired fashion. The circuits within the control 
unit can also be of a type susceptible of damage due to excessive 
electrostatic charge. 
When, as shown in FIG. 1, cartridge 10 is not connected to connector 20, 
fingers 18 of protection device 15 conductively engage associated contacts 
13 of circuit board 12, thereby connecting together (i.e., shorting) these 
contacts and the associated terminals of the (integrated) circuit on board 
12 in a manner which serves to protect the circuit from potential damage 
due to excessive electrostatic charge. 
The internal arrangement of cartridge 10 is better seen from the exploded 
view of FIG. 2. 
In FIG. 2, circuit board 12 is mounted within a lower half 10b of cartridge 
10, which also includes an upper half 10a. The circuit board contains a 
conductive metallized pattern 32 disposed thereon for conductively 
coupling each of contacts 13 with associated circuit terminals 35, which 
in this case are arranged to receive the external terminals of an 
integrated circuit device. 
Upper and lower halves 10a and 10b comprise a housing assembly, or 
cartridge. When these halves are mated together, receptacles 28a and 28b 
(see FIG. 1) are defined, and an aperture is defined through which the 
edge of board 12 with contact areas 13 is exposed externally. The assembly 
is secured by four screws 43a-43d arranged as shown. With these screws in 
place, protection device 15 is secured to the lower cartridge half 10b via 
screws 43a and 43b and associated spacers 45a and 45b, and an end remote 
from the end containing fingers 18. Portions 48a and 48b of device 15 
respectively contact conductive pads 49a and 49b of board 12 when the 
housing assembly is secured. 
Protection device 15 including the plurality of fingers 18 is arranged 
above circuit board 12 such that each of fingers 18 is arranged above 
associated contact areas 13. Device 15 also includes a protuberant region 
40 extending in a direction to contact actuator pins 22a and 22b of 
connector 20 when cartridge 10 and connector 20 are mated. Device 15 is 
resilient and biased so that fingers 18 contact associated contact areas 
13 when the housing assembly is secured, but so that fingers 18 can be 
disengaged from contact areas 13 when a sufficient force is applied to 
protuberance 40 in an upward direction (i.e., away from contact areas 13). 
This force is applied via actuator pins 22a and 22b (See FIG. 1). 
Region 40 is shown as extending along the length of device 15. However, 
region 40 may also comprise dimpled regions situated and extending in a 
direction so as to engage pins 22a and 22b when connector 20 and cartridge 
10 are mated. Top and side profile views of protection device 15 are shown 
in FIGS. 4a and 4b, respectively. 
During the initial phase of mating cartridge 10 with connector 20, initial 
contact is made between protuberant region 40 of device 15 and the beveled 
tips of actuator pins 22a and 22b. Conductive pins 22a and 22b contact 
conductive area 30 of connector 20, and therefore contact the electrical 
ground on the control unit on which connector 20 mounts. Therefore device 
15 with fingers 18, and consequently contact areas 13 and terminals 35, 
also contact the electrical ground. This action equalizes the 
electrostatic potential between board 12 and the control unit in a manner 
which prevents the circuits within the control unit and cartridge 10 from 
being damaged by excessive electrostatic charge. 
Device 15 and pins 22a and 22b are configured such that as cartridge 10 is 
inserted further into connector 20, pins 22a and 22b further engage region 
40 of device 15 such that the portion of device 15 including fingers 18 
and region 40 are forced in an upward direction, away from contact areas 
13 of board 12. Fingers 18 of device 15 are therefore lifted off contact 
areas 13 of board 12, thereby permitting the circuit within cartridge 10 
to operate in desired fashion. During the next and final phase of 
insertion, contacts 13 of cartridge 10 connect with the associated 
receptacles and terminals 24 of connector 20, whereby the circuits within 
cartridge 10 and the control unit are coupled together. FIG. 3 illustrates 
a cut-away side view of a portion of cartridge 10 and connector 20 when 
mated, showing fingers 18 raised above the associated contact areas of 
board 12. 
The reverse sequence of that described above automatically occurs when 
cartridge 10 is withdrawn from connector 20. In this instance, circuit 
terminals 35 remain protected (i.e., shorted) as discussed above.