Patent Publication Number: US-2022226180-A1

Title: Cart for Medical Equipment with Built-In Power Supply

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to, and the benefit of, U.S. Provisional Patent Application No. 63/139,603, filed Jan. 20, 2021. The contents of that application are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     Generally speaking, the invention relates to medical equipment, and more particularly, to carts and power supplies suitable for medical equipment. 
     BACKGROUND 
     Many pieces of medical equipment are designed to be used with multiple patients. This is particularly true of expensive electronic diagnostic equipment, like ultrasound probes. While disposable covers and other kinds of disposable barriers are often used to minimize some types of equipment contamination where and when possible, equipment still gets contaminated, especially if it must enter a body cavity in normal use. 
     Procedures for decontaminating equipment vary widely according to the type of equipment and the types of harsh exposure that the equipment can sustain without damage. For example, handheld metal medical and surgical tools are often autoclaved for high temperature sterilization. Medical devices that include plastic components, or other components that cannot withstand high temperatures, are often chemically disinfected or, in some cases, disinfected by exposure to UV light. 
     The TROPHON® 2 disinfection apparatus (Nanosonics Limited, Sydney, Australia) is one example of a disinfection apparatus that is particularly adapted for surface, transvaginal, and transrectal ultrasound probes. Within a generally rectilinear cabinet, the device uses a chemical disinfectant mist driven by ultrasonic vibration to achieve disinfection. 
     Many pieces of medical equipment are portable. Many pieces of decontamination equipment are not. This means that in most cases, contaminated equipment must be brought to the decontamination equipment. This can cause serious inconvenience for medical staff and an impediment to workflow. If the decontamination equipment can be moved, the means for doing so are often imperfect, and do not provide for all of the equipment&#39;s needs. 
     One of those needs is power. When working with many pieces of medical equipment and disinfection equipment, it is desirable to provide a continuous source of power. If a piece of equipment is turned off, it may be necessary to subject it to time-consuming start-up or recalibration procedures. Most pieces of medical equipment are supplied with alternating-current (AC) power from traditional wall outlets. Uninterruptable power supplies (UPS), which use batteries to store energy and circuitry to deliver that energy as high-voltage AC power, are also becoming more common. 
     Most UPS units are ill-suited for sensitive medical equipment. For example, most lower-end UPS units on the market provide a stepped or square-wave AC voltage waveform, instead of the pure sinusoidal waveform provided by the typical power grid. While some equipment can function using square-wave AC, square-wave UPS systems can also cause unreliability and equipment failure. However, there are very few UPS systems that are particularly adapted for medical equipment and can also facilitate equipment portability. 
     BRIEF SUMMARY 
     One aspect of the invention relates to an equipment cart for medical and disinfection equipment. The equipment cart is designed to mount disinfection equipment in a position near the base of the cart and may include structure to fix the disinfection equipment in place. Casters are provided on the underside of the base to allow for movement of the equipment cart. A telescoping support post supports a work surface at a position above the base and disinfection equipment. The work surface may provide a fully-equipped disinfection workstation with a storage drawer and holders for disinfecting wipes, gloves, and pieces of equipment. Various locking mechanisms may be present, e.g., to lock the storage drawer, and to lock the piece of disinfection equipment to the base of the equipment cart. The equipment cart may have an electrical system to supply power to the disinfection equipment and other peripherals. 
     Another aspect of the invention relates to an electrical system for a medical equipment cart. The electrical system routes power from a high-voltage AC power source to the equipment when a high-voltage AC power source is available. The electrical system also includes a battery and battery charging circuit that are charged using the AC power source when it is available. When the AC power source is not available, the electrical system uses power from the battery to generate a pure AC sine wave, which is then stepped up to high voltage. The pure AC sine wave is generated by generating a first voltage signal and a second voltage signal and sending both voltage signals through a comparator. The first and second voltage signals may be, e.g., triangular waves, with the first signal being a higher-frequency “fast” wave and the second signal being a lower-frequency “slow” wave. The output of the comparator is further processed to generate the pure AC sine wave. For example, a half-wave rectifier and a pair of flip-flops may be used to generate the pure AC sine wave from the output of the comparator. 
     Other aspects, features, and advantages of the invention will be set forth in the description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the description, and in which: 
         FIG. 1  is a perspective view of an equipment cart according to one embodiment of the invention; 
         FIG. 2  is an exploded perspective view of the equipment cart of  FIG. 1 ; 
         FIG. 3  is a side elevational view of the equipment cart of  FIG. 1 ; 
         FIG. 4  is a rear elevational view of the equipment cart of  FIG. 1 ; 
         FIG. 5  is a bottom view of the equipment cart of  FIG. 1 ; 
         FIG. 6  is a perspective view of an equipment cart according to another embodiment of the invention; 
         FIG. 7  is a perspective view of the lower portion of an equipment cart according to embodiments of the invention, illustrating a locking mechanism for retaining equipment; and 
         FIGS. 8-1, 8-2, and 8-3  are each a portion of a circuit diagram of a power supply circuit that may be installed on an equipment cart in embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an equipment cart, generally indicated at  10 , according to one embodiment of the invention. In  FIG. 1 , the equipment cart  10  is shown with a piece of disinfection equipment  12  installed. The disinfection equipment  12  of  FIG. 1  has the size and proportions of the TROPHON® 2 device described above, and may be the TROPHON® 2 device described above, although any disinfection equipment  12  may be mounted on the equipment cart  10 . 
     The equipment cart  10  is intended to serve as a mobile disinfection workstation, with a base  14  that includes casters  16  for movement. In the illustrated embodiment, there are four casters  16 , positioned in a rectangular layout supporting the base  14 , although any number of casters  16  may be used, so long as that number of casters  16  provides for a stable, moveable base  14 . The front casters  16  each have a standard frictional braking mechanism, the actuation levers  18  for which can be seen in  FIG. 1 . The braking mechanism allows the equipment cart  10  to be locked into place once a desired location has been reached. In other embodiments, other forms of wheels may be used to make the equipment cart moveable. 
     The base  14  includes a lower shelf  20 , on which the disinfection equipment  12  rests. A single telescoping support post  22  rises from the base  14  to provide support for the other elements of the equipment cart. At its upper extent, a work surface  24  is cantilevered from the support post  22 . A drawer  26  lies under the work surface  24 . 
       FIG. 2  is an exploded perspective view illustrating the equipment cart  10  with the disinfection equipment  12  exploded out, in order to show the details of the lower shelf  20 . The lower shelf  20  may be of any size that is appropriate for the disinfection equipment  12 . 
     One particular advantage of the equipment cart  10  is that by mounting the disinfection equipment on a low shelf, like the lower shelf  20 , the weight of the disinfection equipment  12  is less likely to tip the equipment cart  10 . Low mounting also means that the equipment cart  10  can include a workspace, like the work surface  24 , at the appropriate height for a user. 
     As shown in the view of  FIG. 2 , the lower shelf  20  may have structure on it to secure the disinfection equipment  12 . That structure may vary from embodiment to embodiment. In some cases, the disinfection equipment  12  may be rigidly clamped to the lower shelf  20 , while in other cases, the structure may be limited to depressions or openings into which the feet or lower portions of the disinfection equipment  12  fit. In the illustrated embodiment, a relatively thick plate  28  is secured to the lower shelf  20 . The bracket  28  has openings  30  in which the feet from the disinfection equipment  12  rest, and forms a locking mechanism for the disinfection equipment  12 , as will be described below in more detail. The forward portion of the lower shelf  20  also forms a berm  32  that helps to prevent the disinfection equipment  12  from shifting out of place when the equipment cart  10  is moved. 
     The orientation of the disinfection equipment  12  on the cart, and the manner in which it opens and is used, may affect the arrangement of the equipment cart  10  and its base  14  and lower shelf  20 . In this embodiment, the disinfection equipment  12  has the form of a cabinet with a hinged door  13  that swings open outwardly. Thus, the height of the berm  32  at the front of the base  14  is sufficient to help retain the disinfection equipment  12 , but not so high as to obstruct the movement of the door  32 . 
     With the disinfection equipment  12  exploded away, other details of the equipment cart  10  can be seen in the view of  FIG. 2 . For example, in the illustrated embodiment, the support post  22  has a rectangular cross-sectional shape with a larger width than its depth. In this embodiment, the support post  22  is in two sections, although more sections may be used, depending on the minimum and maximum heights that are to be used. The telescoping mechanism itself may be of any type. For example, a pneumatic height adjustment mechanism may be used. The height adjustment lever  23  for such a mechanism may be positioned just under the work surface  20 , where it can be easily actuated. 
       FIG. 3  is a side elevational view of the equipment cart  10 ,  FIG. 4  is a rear elevational view, and  FIG. 5  is a bottom plan view. As can be seen in these figures, the equipment cart  10  of the illustrated embodiment is configured to be used as a cleaning workstation, above and beyond the presence of the disinfection equipment  12  itself. The rear corners of the work surface  24  have circular openings  34  that open into cylindrical brackets  36 . These openings  34  and brackets  36  are shaped and sized for the cylindrical cannisters common to disinfecting wet wipes. A glove dispenser  35 , sized for a box of gloves, is also provided in the rear portion of the work surface  24 , between the pair of openings and their associated brackets  36 . A probe holder  38  on one side of the work surface  24  is sized to hold a handheld ultrasound probe for cleaning. A set of circular cut-out openings  40  along the opposite side of the work surface  24  are provided to hold equipment, as are hooks  42  on the lateral sides of the work surface  24 . Below the work surface  24 , a small shelf-holder  44  extends from the upper portion of the support post  22 . The shelf-holder  44  may, for example, be used to hold a printer, such as a label printer. 
     Thus, fully equipped, the equipment cart  10  may serve as a workstation that has all necessary equipment to remove gross soil and contamination from a piece of medical equipment before it is placed in the disinfecting equipment. A laptop and printer may be installed on the work surface  24  and the shelf-holder  44  in order to keep disinfection or other related compliance records. 
     This particular configuration of the equipment cart  10  is not the only possible configuration.  FIG. 6 , for example, is a perspective view of another equipment cart, generally indicated at  50 . The equipment cart  50  is generally identical to the equipment cart  10  described above, except for the configuration of its work surface  52 . The work surface  52  of the equipment cart  50  is stepped, such that the rear area  54  of the work surface  52  is raised. 
     Both equipment carts  10 ,  50  include locks and security measures. Chemical disinfection may involve chemicals that are toxic, corrosive, strong oxidizers, or are otherwise hazardous. For example, chemicals like 35% hydrogen peroxide are common. Because of this, it is helpful if the equipment cart  10 ,  50  has some locks. For example, the drawer  26  may be locked, either with a key lock mechanism, or with a proximity locking mechanism, like a radio-frequency identification (RFID) locking mechanism. An RFID locking mechanism uses a low-power radio-frequency transmitter to interrogate a nearby RF element, which may be either powered or unpowered. If the nearby element transmits the correct identifier, the locking mechanism unlocks. 
     In addition to securing peripherals and chemicals within the drawer  26 , locking mechanisms may be present elsewhere as well.  FIG. 7  is a perspective view of the base  14  of the equipment cart  10 ,  50 , with the disinfection equipment  12  shown in phantom lines. As was described above with respect to  FIG. 2 , there is a plate  28  on the lower shelf  20  of the base  14 . That plate  28  engages with the feet  46  of the disinfection equipment  12  and serves as a locking mechanism. More specifically, the openings  30  in the plate  28  have two sections. With respect to the coordinate system of  FIG. 7 , on the right side of each opening  30 , the walls of the opening  30  are straight-sided. On the left side of each opening, the long walls have a section  47  with walls that are canted inward. The inward cant of the left section  47  of the opening  30  matches a cant of the feet  46 , meaning that in the position shown in  FIG. 7 , the disinfection equipment is positively engaged by the plate  28 . In order to release the engagement, it is necessary to slide the plate  28  to the left, so that the feet  46  are no longer engaged by the canted sections  47  of the openings. However, another locking mechanism  48  is mounted within the base  14 , with an upwardly projecting bolt  49  that engages a complementary opening in the plate  28  to lock it in place. When the bolt  49  is in the position shown in  FIG. 7 , the plate  28  cannot be slid rightward to disengage the canted sections  47  from the feet  46  of the disinfection equipment  12 ; thus, the disinfection equipment  12  cannot be lifted from the base  14 . When the locking mechanism  48  is disengaged and the bolt  49  is withdrawn, the plate  28  can be slid rightward, freeing the disinfection equipment. The locking mechanism  48  may be a key-actuated locking mechanism, an RFID locking mechanism, or a locking mechanism that is actuated in some other way. In addition to preventing the unauthorized removal or theft of the disinfection equipment  12  from the equipment cart  10 ,  50 , the plate  28  and its locking mechanism  48  also serve to secure the disinfection equipment  12  during movement of the equipment cart  10 ,  50  and against earthquake and other hazards. 
     The plate  28  and its openings  30  take advantage of an existing cant to the feet  46  of the disinfection equipment  12 . As those of skill in the art will realize, many kinds of cooperating engaging features may be used to lock a structure such as the plate  28  to a piece of disinfection equipment. 
     The equipment carts  10 ,  50  have their own onboard electrical systems. As can be seen in  FIGS. 1-6 , electrical outlets  55  are provided on one side of the support post  22  to supply power to the disinfection equipment  12  and to other peripherals that may be used with the equipment carts  10 ,  50 . The main components of the electrical system are contained in a housing  56  that is mounted on the underside of the lower shelf  20 . The housing  56  is electrically connected to an outlet  58  at the lower rear of the equipment cart  10 ,  50 . The outlet  58  serves as a connector to plug the equipment cart  10 ,  50  into AC mains (i.e., building) power. 
       FIGS. 8-1, 8-2, and 8-3  are circuit diagrams of the main circuit, generally indicated at  100 , of the equipment carts  10 ,  50 , each figure showing a portion of the main circuit  100 . For purposes of description, it may be assumed that the circuit illustrated in  FIGS. 8-1 through 8-3  resides in the housing  56 , although portions of the circuit may reside in other physical locations. 
     The main circuit  100  provides AC power to the electrical outlets  54  with a pure AC sine wave, even when it is not connected to internal power. To do this, it includes both high-voltage portions and low-voltage portions. (While the definition of “high voltage” varies according to the authority one consults, for purposes of this description, the term will refer to voltages over 50V.) Much of the high-voltage portion  102  of the circuit  100  is shown in  FIG. 8-2 . 
     The main circuit  100  illustrated in  FIGS. 8-1 through 8-3  supplies power to the disinfection equipment  12  and the other equipment associated with the equipment cart  10 ,  50  from AC mains power when AC mains power is available, and from a battery when AC mains power is not available. Switching between these two power supplies will consume some short interval of time; thus, the main circuit  100  of  FIGS. 8-1 through 8-3  may not be considered a “full” or “traditional” UPS in some contexts. In other embodiments, a power circuit may supply power entirely through a battery, using AC mains power, when available, to charge the battery. Thus, for purposes of this description, the term “UPS” should be read to include power circuits that switch between a battery and another power source, as well as power circuits that always supply power through a battery, but use another power source, if one is available, to maintain the battery&#39;s charge. 
     In the main circuit  100  of  FIG. 8-2 , switch  51  in  FIG. 8-2  is a high-voltage DPDT breaker that supplies power to the power outlets  54  directly from AC mains power when AC mains power is available. As can be seen from the diagram of the high-voltage portion  102 , the high-voltage portion  102  of this embodiment does not have particular power conditioning components (e.g., filters), although it may be provided with such components in other embodiments. 
     The switch S 1  is connected to a relay U 8 . 1  that connects either to the AC power, indicated as U 2  in  FIG. 8-2 , or to a transformer T 2  connected to the output of the signal generation portion  104  of the circuit  100 . Thus, the relay U 8 . 1  allows the power outlets  54  to be fed either directly by AC power or by battery-driven pure AC sine wave generated by the signal generation portion  104 . 
     Power from the AC power U 2  in  FIG. 8-1  is routed to transformer T 1  in  FIG. 8-3 , which, in this embodiment, is a 32V transformer that steps the power down from 120 VAC to 32 VAC. On the low-voltage side, power from the transformer T 1  is fed to diodes D 2 , D 3 , D 4 , D 6 , which are in a full-bridge rectifier configuration and rectify the 32V AC power into 32V DC. The remainder of the circuit  100  shown in  FIG. 8-3  is a battery charger for the 24V battery V 1  ( FIG. 8-2 ) that supplies power when the circuit  100  is not connected to external AC power. This battery charge portion  106  of the circuit uses an LM358 dual op-amp integrated circuit (IC) U 9 , U 10  as comparators to monitor the voltage of the battery V 1  during charge by sensing high-voltage (i.e., 28.8V) and low-voltage (i.e., 21.6V) conditions. When the voltage has reached the desired charge voltage, indicating that the battery V 1  is fully charged, a voltage applied by the op amp U 10  to the gate of the transistor Q 3  cuts off the charge. 
     As those of skill in the art will realize, a full diagram of the battery charge portion  106  is included in  FIG. 8-3  only for the sake of completeness; any suitable battery charging circuit may be used in embodiments of the invention. 
     As was noted briefly above, when the circuit  100  is not drawing power from AC mains, it draws from the battery V 1  and modulates that power into a pure AC sine wave within the low-voltage signal generation portion  104  of the circuit  100 . The low-voltage pure AC sine wave is then stepped up from low voltage to high voltage by the transformer T 2 . 
     Much of the low-voltage signal generation portion  104  is shown in  FIG. 8-1 , with the remainder in  FIG. 8-2 . Conceptually, the low-voltage signal generation portion  104  achieves its task by generating two waveforms of different characteristics and using those two waveforms as inputs to an op amp configured as a comparator. The output from the op-amp is used to create a series of half-waves, which is sent to a pair of flip-flops that generate the fully alternating sine wave from the half waves. 
     More specifically, the two waveforms of different characteristics are triangular or sawtooth-type waveforms in this embodiment. The first of the two sawtooth-type waveforms is generated by an NE 555 P timer IC U 3 . The connection of the  555  timer IC U 3  with the resistors R 13 , R 14  and capacitor C 12  places the  555  timer IC in an astable configuration, allowing it to act as an oscillator. The voltage across the capacitor C 12  is a triangular or sawtooth waveform in this configuration, and that waveform is sent to the noninverting input of an LM 741 CN op amp U. 
     A broader, “slower” triangular waveform is generated by a CD 4047  multivibrator IC U 1  in astable free-running operating mode. This output is connected to the inverting input of the LM 741 CN op amp U. 
     As was described briefly above, the output from the op amp U is first sent to two diodes D 5 , D 8  in a half-wave rectifier configuration. The output of those diodes is sent to two IRF 3205  flip-flops M 1 , M 2 , shown in  FIG. 8-2 , one set high and one set low, that produce a full sinusoid from the half-wave output of the diodes D 5 , D 8 . That sinusoid, still at low voltage, is stepped-up by the transformer T 2  to high voltage, as was described above. 
     Unless otherwise noted, all electronic components in the circuit  100  are manufactured by, or can be obtained from, Texas Instruments, Inc. (Dallas, Tex., United States). As those of skill in the art will understand, the topology and components shown in  FIGS. 8-1, 8-2, and 8-3  are only one way to implement a UPS with a “pure” sine wave power output. Variations and other approaches are possible. 
     While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.