Abstract:
A connector is provided for preventing damage to contacts between components of an electrical system which is particularly useful when electrical energy is stored in at least one of the components. The connector includes a mechanically operated latching member for activating and deactivating an electrical interface between the components. In one embodiment, a sensor determines when the connector is being disconnected from one of the components and provides a signal used by one of the components for disabling a power source providing the energy. In another embodiment, the sensor derived disconnect signal controls dissipating the stored energy away from the contacts between the components before the contacts are physically disengaged.

Description:
FIELD OF THE INVENTION 
     This invention relates to connectors used to interface components of electrically-based systems, such as, for example, imaging systems having image-acquiring and image-displaying components. A preferred application of the present invention relates to ultrasound systems. 
     BACKGROUND OF THE INVENTION 
     Ultrasound systems generally have an ultrasonic transducer component disposed in a probe (the probe generally comprising a scanhead attached to a cable), and an imaging system component in communication with the transducer. Typically, a number of different types of probes can be used with a given imaging system, depending on the environment of the body part sought to be imaged. For example, in imaging a fetus in the abdomen, a probe having a relatively large scanhead is used to obtain a wide field of view; while in imaging the heart viewed from the esophagus, a probe having a very small scanhead is desirable, to minimize discomfort to the patient. However, the same imaging system can be used for either probe. Therefore, a connector is provided at the end of the probe cable such that different probes can be used with the imaging system, depending on the desired ultrasound application. In a similar manner, various peripherals can be plugged into and out of all manner of imaging systems, computer systems, and the like. 
     If a power source such as a transmitter is pulsing and/or if there is stored electrical energy in a system when a connector between components is disengaged (such as, for example, when one probe in an ultrasound diagnostic system is being replaced with another), there is the potential for an electric arc to cross the contacts between the connector and the connected component of the system (the imaging system, in the ultrasound context). Such an arc can cause serious damage to the system contacts and/or the contacts of the connected component. 
     Therefore, a need exists for a connector that can protect a system, and particularly an imaging system and/or its transducer components such as found in ultrasound applications, from the potentially adverse effects of removing a peripheral from the rest of the system before transmitters are disabled and/or stored electrical energy has dissipated. 
     A previous method for preventing contact damage is used in ultrasonic imaging systems from Hewlett Packard (Palo Alto, Calif.) (HP Models 1000, 2000 &amp; 2500), substantially as shown in FIG. 9. This method uses a first latching mechanism which engages the connection contacts and a second latching mechanism which enables the transmitter circuits only after both latching mechanisms are engaged. Thus, a mechanical arrangement is used such that the probe cannot be disengaged from the imaging system before the second latching mechanism is disengaged and the transmitters disabled. 
     SUMMARY OF THE INVENTION 
     The current invention represents an improvement over HP&#39;s method because the connector latching mechanism conveys information about its state to the system, eliminating any need for a second latching mechanism. 
     Accordingly, one object of the invention is to provide a connector that will prevent an arc from damaging contacts between the connector and the connected system components without requiring the operator to perform any additional tasks. 
     Another object is to provide an ultrasound system in which various probes can be interchangeably connected to an imaging system, without risk of arcing upon disengagement of the probes. 
     In accordance with the above objects and those that will be mentioned and will become apparent below, the invention comprises a connector for preventing damage to contacts between components of an electrical system when electrical energy is provided by a power source disposed within a first component of the system and directed by circuitry to a second component of the system. The connector comprises a mechanically operated latching means for activating and deactivating an electrical interface between the first and second components. The latching means has an engaged mode and a disengaged mode. Sensor means is coupled to the latching means, for sensing the mode of the latching means. The connector also comprises means, coupled to the sensor means, for conveying information revealing the mode of the latching means to at least one of the components of the system, which component in turn comprises means for disabling the power source upon receipt of the information revealing disengagement of the latching means. 
     According to another aspect of the invention, a connector is provided, having a mechanically operated latch for activating and deactivating an electrical interface between components of an electrical system. A sensor, coupled to the latch, reveals the position of the latch to an arc protection circuit in one of the components. The arc protection circuit causes the transmitters to be shut off and/or dissipation of stored energy away from the contacts, before the contacts can be physically separated. 
     According to another aspect of the invention, an ultrasound system is provided for obtaining diagnostic information from the interior of a body. The ultrasound system comprises a scanhead having a transmitter pulser and an ultrasonic transducer for propagating ultrasonic beams into the body and receiving ultrasonic echoes therefrom; an imaging system for displaying information received from the ultrasonic echoes; and a connector for providing an electrical interface between the transducer and the imaging system. The connector comprises latching means, for activating the interface; sensor means, for sensing whether the latching means is engaged or disengaged; and means, coupled to the sensor means, for conveying information revealing the status of the latching means to the electrical interface and/or the imaging system. Means are provided in the electrical interface and/or the imaging system for shutting off the transmitter pulser and/or dissipating stored energy when the latching means is disengaged. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the objects and advantages of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings in which like parts are given like reference numerals in the various figures, and wherein: 
     FIG. 1A is a side cross sectional view of the connector of a preferred embodiment of the invention, with FIG. 1B showing the detail. 
     FIG. 2 is a detail view, corresponding to that shown in FIG. 1B, of a second embodiment of the connector of the invention. 
     FIG. 3 is a detail view, corresponding to that shown in FIG. 1B, of a third embodiment of the connector of the invention. 
     FIG. 4 is a detail view, corresponding to that shown in FIG. 1B, of a fourth embodiment of the connector of the invention. 
     FIG. 5 is a schematic diagram of a preferred embodiment of the ultrasound system of the invention. 
     FIG. 6 is schematic diagram illustrating an alternative embodiment of the ultrasound system of the invention. 
     FIG. 7 is a side cross-sectional and bottom view of an alternative embodiment of the sensor and key of the present invention. 
     FIGS. 8A and 8B are two-view drawings of two possible embodiments of the connector, illustrating the contact actuation means. 
     FIG. 9 is an illustration of HP&#39;s two-latch method for preventing contact damage. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings, FIG. 1 shows a connector 10 having a housing 12. Axially through the housing 12 extends actuator shaft 14, with handle 15 of shaft 14 disposed outside the connector housing 12, such that the shaft 14 can be manually rotated. An opaque shutter 16 is affixed to the base of the shaft 14, such that when the handle 15 of the shaft is rotated, the shutter 16 rotates with the shaft 14. An optical sensor 18 is seated in the housing 12. In a particularly preferred embodiment, the optical sensor 18 comprises a light emitting diode 20 and a phototransistor 22, which together define an optical path 24. When the handle 15 and shaft 14 are rotated fully clockwise from the operator&#39;s point of view, the shutter 16 blocks the optical path 24 and the actuator shaft 14 is in a fully latched position; this position is referred to as the engaged mode. When the handle 15 and shaft 14 are rotated counter-clockwise, the shutter 16 moves out of the way of the optical path 24, and the actuator shaft 14 is in a disengaged mode. 
     FIG. 5 is a simplified schematic of the circuitry in an ultrasound system showing one of many imaging channels. A typical ultrasound system will have, for example, 128 such channels: one for each transducer element 37 in the scanhead 38. Each element 37 in scanhead 38 is attached to a cable 39, which is in turn connected to connector 10. Connector 10 is connected and disconnected to imaging system 50 at contacts 42 and 44 and other similar contacts. 
     In a preferred embodiment, when the actuator shaft 14 is within about 10 degrees of full engagement, the shutter 16 blocks the optical path 24 of the LED 20 and phototransistor 22 (collectively, &#34;the sensor 18&#34;), and the sensor 18 sends a &#34;connector engaged&#34; signal on line 48 to transmitter circuitry 40, as shown in FIG. 5. When the actuator shaft 14 is rotated away from full engagement, the shutter 16 pulls out of the sensor&#39;s optical path 24 and the signal sent to transmitter circuitry 40 on line 48 changes to &#34;connector disengaged.&#34; The sensor 18 is powered through an additional contact 43. 
     The &#34;connector disengaged&#34; signal is sent before physical engagement of contacts 42 and 44 (and other similar contacts) between the connector 10 and the imaging system 50 can be broken. The actuator shaft 14 and connector 10 are configured such that the actuator shaft 14 must be further rotated in the counterclockwise direction to break physical engagement of contacts 42 and 44. This feature can be provided by a mechanical slot 6 (on the imaging system board) and actuator pin 8 (on the actuator shaft 14) arrangement, preventing mechanical disengagement of the contacts between the imaging system 50 and the connector 10 (as shown in FIG. 1 ), or by other means known in the art. Therefore, a time interval is provided between the approximately 10 degree rotation at which the &#34;connector disengaged&#34; signal is sent, and the further rotation of the actuator shaft 14 (preferably about 110 degrees) physically required by the slot 6 and pin 8 arrangement (or other conventional means) to break physical engagement of contacts 42 and 44. During this time interval, means can be provided for disabling the transmitters and dissipating stored energy, such as from inductor 52, so that it does not arc across the contacts 42 and 44 by the time the rotation is complete and the connector 10 can be physically removed from the imaging system 50. At a minimum, the time interval should be at least about 5 milliseconds to make sure the transmitters are shut off; but preferably, at least about ten milliseconds. 
     Two ways of obtaining the delay are shown in FIGS. 8A and B, respectively. 
     FIG. 8A shows a pin 100 and ramp 102 arrangement, wherein rotation of the actuator shaft 14 causes the connector 12 to be drawn toward the system board 50 compressing the contacts 104. The contacts are designed to be compliant so an electrical connection is established over at least about 50% of the rotation range of the actuator shaft, providing a delay between the operator&#39;s initial counter-clockwise rotation of the shaft and separation of the contacts. 
     FIG. 8B shows an alternate arrangement, wherein rotation of the actuator shaft 14 rotates a cam 106 which in turn pushes groups of moving contacts 108 housed in contact shells away from the center of the connector causing them to establish an electrical connection with stationary contacts 114 in the system connector 112. The actuated contacts 108 displace with sufficient compliance that they provide a delay as described above. The displacement can be by bending flexible contacts as shown in FIG. 8B, or, alternatively, by compressing a spring loaded structure (not shown). Any arrangement utilizing compliant contacts and an actuator with extra travel beyond that required for electrical connection will provide the required delay. 
     In the illustrated embodiment of FIG. 5, the transmitter circuit 40 comprises a pulser 46, and a transmitter amplifier represented here as an ideal amplifier 47 and an output resistor 54. The signal from the sensor 18 causes transmitter pulser 46 to be shut down, e.g., by deasserting an enabling logic input at line 48, and thereby causes the dissipation of stored energy of inductor 52 through the transmitter amplifier output impedance 54. As an alternative embodiment, a simple electronic switch can be inserted between pulser 46 and amplifier 47, instead of the logic input at line 48. By the time actuator shaft 14 has been fully rotated, beyond the &#34;disengaged&#34; position to a position from which the connector can be physically removed from the imaging system circuitry 50 contacts 42 and 44, enough time will have lapsed to shut down the transmitters and permit dissipation of the stored energy. In the preferred embodiment, it has been found that manual rotation of the shaft 14 from 10 to 110 degrees typically provides a time delay of at least 10 milliseconds. The time required for dissipation is generally under a millisecond, but it takes about 5 milliseconds to shut down the transmitter circuits 40, which are continuing to send more energy into the inductors. To provide a longer time delay and a larger margin of safety, the actuator mechanism can be configured such that more rotation is needed, e.g., 120, 180, or even 350 degrees, to physically break the contacts between the connector 10 and the imaging system 50. The actuator mechanism can be, for example, as represented by a pin and ramp arrangement 100, 102 in FIG. 8A; or a cam and block arrangement arrangement 106, 110 in FIG. 8B; or a slot and pin arrangement as represented by 6, 8 in FIG. 1A. In FIG. 8A, the pin 100 can equivalently be replaced by a roller. All of these actuator mechanisms can be used in conjunction with a ZIF connector as described above, or alternatively, with a conventional connector. 
     To practice a preferred embodiment of the invention, the ultrasound operator fully engages the connector 10 to activate the electrical interface between the probe 55 and the imaging system 50 by rotating the handle 15 of actuator shaft 14 in a clockwise direction, substantially as far as it will go, to place the latching means in the engaged position or mode. To remove probe 55, the operator rotates the handle 15 in the opposite direction. During the earliest portion of the rotation, the latch is disengaged, at which time the sensor sends a signal to imaging system circuitry 40. (In alternative embodiments, the signal can be sent to transducer circuitry or connector circuitry). Upon receipt of the &#34;connector disengaged&#34; signal, the imaging system circuitry 50 in the preferred embodiment (or transducer or connector circuitry in alternative embodiments) causes the transmitters 46 to be shut down and/or causes energy stored in the system to be dissipated away from the contacts 42, 44 before the contacts can be physically disengaged from each other. In the preferred embodiment, the stored energy is in tuning inductors 52 within the connector 10; however, in alternative embodiments the inductors 52 are placed in the scanhead 38. 
     In a preferred embodiment of the invention, the means for turning off the transmitters and dissipating stored energy utilizes the same imaging system circuitry used to control the temperature of the probe 55 (see FIG. 6). Current FDA regulations for diagnostic ultrasound require that the probe temperature not exceed 41 degrees Celsius. In a preferred embodiment, the temperature of the probe face is monitored by temperature sensor circuitry 53 in the scanhead. When the temperature in the scanhead reaches a certain threshold, a signal is sent from the temperature sensor circuitry 53 to the imaging system 50, whereupon the control signal on line 48 shuts down the transmitter 46, allowing the probe to cool down. 
     In the preferred embodiment, an array of 128 transducer elements 37 is used, made of a piezoelectric material known as PZT (lead zirconate titanate), obtained as P/N 3203 HD from Motorola. The cable 39 consists of 132, 38-gauge, served wire-shield coaxial channels, and can be obtained from W. L. Gore in Phoenix, Ariz. as P/N 02-07202, or from Precision Interconnect in Portland, Oreg. as P/N 171041800. The connector 10 can be, for example, an ITT/Cannon DL156 zero insertion force (ZIF) connector, or a micro-coax ZIF Interposer connector that can be obtained from AMP in Harrisburg, Pa. The stored energy dissipated away from the contacts 42, 44 in the preferred embodiments is accumulated in an array of 128 tuning inductors 52 (one per channel) in the connector 10. The inductors 52 are preferably surface mount inductors, obtained from Dale Electronics, Inc. in Yankton, S. Dak., or American Precision Industries in East Aurora, N.Y. There is an array of 128 transmitter circuits (one per channel) in the imaging system, which are built from readily available discrete and integrated electronic components, as known in the art. 
     Other types of sensors 18 can be used within the spirit and scope of this invention, as illustrated in FIGS. 2-4. For example, in FIG. 2, a reflection-type optical sensor is shown, having a reflective tab 26 instead of an opaque shutter attached to the actuator shaft 14. In FIG. 3, a magnetic sensor 30 is used in conjunction with a permanent magnet 31 mounted on the actuator shaft 14. Alternative sensors are a Hall-effect sensor, and a magnetic reed switch. The latter has the advantage of not requiring external power for its operation. In yet another embodiment, shown in FIG. 4, a mechanical spring-loaded switch 36 is used, actuated by a cam structure attached to the actuator shaft 14, having a shaft-mounted cam 32 and a push rod 34 extending therefrom. 
     The alternate embodiment shown in FIG. 6 is useful in systems that cannot be fitted with an additional connection for conveying the state of the connector latch to the imaging system. Also, this embodiment uses a passive actuation shaft sensor that does not require power from the imaging system. Contacts 51 for connecting a thermal sensor or sensors 53 to the imaging system and contacts 55 for conveying probe identification information to the imaging system are already available in the equipment. In this embodiment the actuator shaft position is sensed by a magnetic switch 30 or a mechanical switch 36 as shown in FIGS. 3 and 4 respectively. In either case the switch comprises two poles 59 and 60 which interrupt the temperature sensor and probe identification signals, respectively, upon actuator disengagement of at least 10 degrees. Circuits 56, 57 and 58 interpret this change of state as a complete probe disengagement, and shut down the transmitter pulser 46 as described in the discussion of FIG. 5. Circuit 56, in a preferred embodiment, is an analog circuit that measures the temperature at thermal sensor 53 and reports excessive temperature to logic circuit 58. Logic circuit 57 detects presence of and identity (type) of probe. Logic circuit 58 controls the pulser enabling signal 48 in a binary manner. 
     In other embodiments, the sensor is mounted integrally with the imaging system instead of inside the connector housing, as shown, for example, in FIG. 7. In still other embodiments, the actuator can be a lever, hinged, for example, on a horizontal axis, rather than a rotating shaft oriented on a vertical axis relative to the system board. Many such changes and permutations will be apparent to one skilled in the art, and within the scope and spirit of the instant invention. 
     Any other electrical or electronic system consisting of a host system and at least one peripheral attached by way of separable electrical connectors can be equipped with some variant of the contact-protecting connector described above. Systems which include energy-storing devices such as capacitors or inductors will benefit most from this type of treatment. 
     For example, in computers with interchangeable circuit boards it is sometimes useful to be able to remove or insert boards while the system is operating. Normally, this causes damage to the board and system contacts, but with a properly-designed connector actuator and sensor such damage can be prevented. Similarly, peripherals like monitors and disk drives could also be &#34;hot-plugged.&#34; 
     Appliances such as space heaters and kitchen mixers that draw large currents from their wall outlet power sources could be fitted with an actuated power connector to prevent current from flowing until the connector contacts are fully engaged, thereby preventing contact damage. 
     It will be apparent to one of ordinary skill in the art that many changes to the foregoing configurations described as the presently preferred embodiments can be made within the scope and spirit of the invention. For example, the inductors (or capacitors or other energy storage devices) need not be in the connector, but can be placed in the scanhead. Similarly, the energy dissipating circuitry can be placed in the connector rather than in the imaging system, e.g., by placing an electronic switch and resistor in series across the tuning inductor. All manner of configurations are within the scope of this invention so long as they do not interfere with the normal operation of the ultrasound (or other imaging or multicomponent) system, while providing the function of shutting off a functioning power source and/or diverting and dissipating stored energy away from the contacts to avoid the risk of contact damage from arcing. Accordingly, the scope of this invention is not to be construed in light of the detailed description, which is meant to be illustrative and not limiting; but is intended to be construed in accordance with the following claims, and all legal equivalents thereto.