Abstract:
A position indicator display system for an elevator. The elevator position indicator has a segmented display capable of producing alpha-numeric characters. The segmented display operates in a predetermined power range that may or may not match the operational voltage used by the rest of the elevator&#39;s systems. Within the elevator position indicator, a display driver is coupled to the segmented display. The display driver receives a location signal from the systems controller of the elevator. The display driver arranges the location signal to drive the segmented display and produce an alpha-numeric character indicative of the location signal. Since the elevator&#39;s operational voltage may differ from that of the elevator position indicator, a power conditioning circuit is provided. The power conditioning circuit selectively alters the power of the location signal so that the location signal falls within the operational power range of the segmented display.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the design of position indicator displays for elevators. More particularly, the present invention relates to the circuitry used to drive a segmented display in the applications of an elevator position indicator. 
     2. Description of the Prior Art 
     Elevator position indicator displays are the displays that inform a person of the floor location of a particular elevator car at a particular moment in time. Elevator position indicator displays are commonly located in the lobby of buildings and within the actual cars of the elevator. The elevator position indicator display in the lobby of a building informs people in the lobby of the position and direction of the elevator car. In this manner they can gauge how long the wait will be before the elevator reaches the lobby. The elevator position indicator display within the elevator car informs a person of the floor level of the elevator so they know when to disembark the elevator car. 
     There are many different types of elevator position indicator displays, and there are no standards for their design. Additionally, different elevator systems operate at different supply voltages. Many elevator systems operate with twenty four volt power supplies. Other elevator systems are powered by one hundred and twenty volt power supplies. To further complicate matters, some elevator systems operate with alternating current, while others operate with direct current. 
     In addition to the wide range of power requirements used by various elevator systems, there is an equally large variety of position indicator displays in use. Although many of these position indicator displays use a segmented display to create alpha-numeric characters, the display drive circuits used to drive the segmented displays vary widely. The prior art of display diver circuits are exemplified by U.S. Pat. No. 5,644,326 to Lauzon, entitled, Display Device With Electrically Interconnected Display Elements; U.S. Pat. No. 5,703,607 to Tai, entitled Drive Circuit For Displaying Seven Segment Decimal Digit; U.S. Pat. No. 5,969,628 to Andre, entitled, Display Device For A 7-Segment Font; and U.S. Pat. No. 3,146,436 to Crow, entitled, Arabic Numeral Display Having Binary Code Conversion Matrix. Due to the complex designs of many display drive circuits, many displays are expensive to manufacture and complicated to repair. 
     Since elevators systems have different power requirements and vary in design, it is often difficult to repair or replace the elevator position indicator display used within that system. A need therefore exists in the art for a low cost versatile elevator position indicator display that can be retroactively added to most any elevator, regardless of the power specification used by that elevator. A need also exists for a simplified elevator position indicator display that uses a minimal amount of wiring and is easily maintained and repaired. These needs are met by the present invention as it is described and claimed below. 
     SUMMARY OF THE INVENTION 
     The present invention is a position indicator display system for an elevator. The elevator position indicator has a segmented display capable of producing alpha-numeric characters. The segmented display operates in a predetermined power range that may or may not match the operational voltage used by the rest of the elevator&#39;s systems. Within the elevator position indicator, a display driver is coupled to the segmented display. The display driver receives a location signal from the systems controller of the elevator. The display driver arranges the location signal to drive the segmented display and produce an alpha-numeric character indicative of the location signal. Since the elevator&#39;s operational voltage may differ from that of the elevator position indicator, a power conditioning circuit is provided. The power conditioning circuit selectively alters the power of the location signal so that the location signal falls within the operational power range of the segmented display. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference is made to the following description of an exemplary embodiment thereof, considered in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a schematic of an elevator system having an elevator position indicator; 
     FIG. 2 is a schematic of a seven segment display; 
     FIG. 3 is a schematic of a sixteen segment display; 
     FIG. 4 is a schematic of an elevator position indicator that utilizes twelve possible location signals; 
     FIG. 5 is a schematic of an elevator position indicator that utilizes three possible location signals; and 
     FIG. 6 is a schematic of a segment of display drive circuit that uses connector ports that receive voltage steering devices. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the present invention device can be adapted to drive segmented displays in a variety of application, the present invention device is particularly well suited to drive segmented displays that are part of an elevator position indicator. Accordingly, in order to present the best mode contemplated for the present invention device, the device will be described embodied as part of an elevator position indicator. 
     Referring to FIG. 1, there is shown a schematic of an overall elevator system  11  as it relates to the elevator&#39;s systems controller  16  and the elevator position indicator. The elevator position indicator contains a digital segmented display  12  which is comprised of either seven separate segments or sixteen separate segments. The segmented display  12  itself can be either a back-lit liquid crystal display or a light emitting diode array, as is typical for segmented displays. 
     The elevator system  11  detects the position of the elevator car using various elevator sensors  14  that are positioned in the elevator shaft. The sensors read the position of the elevator car to the elevator systems controller  16 . The elevator systems controller  16  sends signals to the elevator position indicator  10  so that the segmented display  12  will show the floor location of the elevator car using an alpha-numeric character. 
     A seven segment display is all that is required if the floor locations of the elevator include a lobby and numerically numbered floors. The sixteen segment display is required if alphabetic characters such as “G” for garage or “M” for mezzanine are to be displayed. 
     The overall elevator system  11  operates at some operational voltage and current type. The present invention position indicator  10  provides a display that can function at multiple operational voltages and current types. As such, the elevator position indicator  10  can be added to a variety of existing elevator systems. 
     Referring to FIG. 2, a schematic is shown for the seven segment display  12 . The seven segment display  12  has seven segments. The seven segments are labeled with the labels a, b, c, d, e, f and g, respectively. Each segment of the display is either an LED or an energizable segment of an LCD, depending upon the type of display used. To create the number “1”, segments b and c are energized. To create the number “2”, segments a, b, d, e and g are energized. Other letters and numbers can be created by referring to the following table, where the x&#39;s indicate the segments that are energized. 
     
       
         
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                   
                 Segment 
               
             
          
           
               
                   
                 Number 
                 a 
                 b 
                 c 
                 d 
                 e 
                 f 
                 g 
               
               
                   
                   
               
               
                   
                 1: 
                   
                 X 
                 X 
                   
                   
                   
                   
               
               
                   
                 2: 
                 X 
                 X 
                   
                 X 
                 X 
                   
                 X 
               
               
                   
                 3: 
                 X 
                 X 
                 X 
                 X 
                   
                   
                 X 
               
               
                   
                 4: 
                   
                 X 
                 X 
                   
                   
                 X 
                 X 
               
               
                   
                 5: 
                 X 
                   
                 X 
                 X 
                   
                 X 
                 X 
               
               
                   
                 6: 
                 X 
                   
                 X 
                 X 
                 X 
                 X 
                 X 
               
               
                   
                 7: 
                 X 
                 X 
                 X 
               
               
                   
                 8: 
                 X 
                 X 
                 X 
                 X 
                 X 
                 X 
                 X 
               
               
                   
                 9: 
                 X 
                 X 
                 X 
                 X 
                   
                 X 
                 X 
               
               
                   
                 0: 
                 X 
                 X 
                 X 
                 X 
                 X 
                 X 
               
               
                   
                 L: 
                   
                   
                   
                 X 
                 X 
                 X 
               
               
                   
                 P: 
                 X 
                 X 
                   
                   
                 X 
                 X 
                 X 
               
               
                   
                   
               
             
          
         
       
     
     Referring to FIG. 3, a schematic is shown for the sixteen segment display  15 . The sixteen segment display  15  has sixteen segments. The sixteen segments are labeled with the labels a, b, c, d, e, f, g, h, i, j, k, l, m, n, o and p, respectively. Such a sixteen segment display  15  is capable of producing any alpha-numeric character. For example, to produce the letter “M”, segments c, d, h, g, i and k are energized. To produce the letter “G” segments a, b, d, e, f, g, h, and p are energized. 
     The sixteen segment display  15  can be used. However, for the sake of simplicity, it will be assumed that the seven segment display of FIG. 2 is being used in the remaining description of the present invention. 
     Referring now to FIG. 4, a wiring schematic is shown that illustrates the major components of the elevator position indicator. The elevator position indicator preferably includes a rectifying circuit  20  that receives either AC or DC signals from the systems controller  16  of the overall elevator system. The rectifying circuit  20  converts the signals into direct current in a manner which will later be explained with reference to FIG.  5 . If the signals received from the systems controller  16  of the overall elevator system are already using direct current, the rectifying circuit  20  need not be present. 
     The signals produced by the elevator systems controller are position signals that indicate the position of an elevator car in the elevator system. After location signals from the elevator&#39;s system controller are rectified, the location signals pass into a display drive circuit  22 . The purpose of the display drive circuit  22  is to drive the segmented display  12  and ensure that the segmented display  12  displays the proper alpha-numeric character as instructed by the received location signal. 
     The display drive circuit  22  contains seven vertical lines  24  which correspond to the seven segments of the segmented display  12 . Also shown in FIG. 4 are twelve horizontal lines  26  that correspond to the twelve possible display commands that can be produced by the elevator&#39;s system controller  16 . The display commands are the numerals “0” through “9” and the letters “P” and “L” as is listed above in Table 1. 
     Disposed between the various vertical lines  24  and horizontal lines  26  of the drive circuit  22  are diodes  28  that control the direction of current flow. In FIG. 4, it can be seen that the horizontal line for the received location signal for the number “1” is coupled with diodes to vertical line “b” and vertical line “c”. This shows that to produce the number “1” the “b” and “c” segments (FIG. 2) in the seven segment display  12  are to be lit. As such, it will be understood that the drive circuit  22  of FIG. 4 corresponds to Table 1 with regard to what segments of the seven segment display  12  are to be energized to produce different alpha-numeric characters. 
     After the drive circuit  22  directs the various location signals to the proper pathways, as represented by the vertical lines  24 , the location signals pass through a power conditioning circuit  30 . The power conditioning circuit. 30  ensures that the current of the location signals is not above the capacity of the segmented display  12 . The details of the power conditioning circuit  30  will later be described with reference to FIG.  5 . 
     Lastly, the location signals are received by the segmented display  12 . Depending upon which of the twelve possible location signals are received, the segmented display will produce one of the twelve alpha-numeric characters listed in Table 1. 
     The wiring schematic shown in FIG. 4 would be used on an elevator operating in a building having a parking garage, a lobby and ten floors. This would provide the twelve possible command signals listed in Table 1. However, the system can be used for elevator systems having any other number of floors. 
     Referring to FIG. 5, the present invention system is configured for an elevator that services only three floors. The elevator has three levels represented by “L” for the lobby, “2” for the second floor and “3” for the third floor. As such, the systems controller of the elevator produces one of three location signals depending upon the position of the elevator car. Those three signals are “L”, “2” and “3”. A control wire  50  is, provided for each of the possible location signals. 
     If the location signal produced by the systems controller of the elevator is a direct current signal, then the signal need not be rectified. However, if the position signals are in alternating current, the signals must be rectified. In FIG. 5, an exemplary embodiment of a rectifying scheme is shown. In the embodiment of FIG. 5, a full wave bridge rectifier  52  is provided along each control wire  50 . The full wave bridge rectifiers  52  rectify the A/C location signals. In circuit design, there are many circuits that perform the same function as a full wave bridge rectifier, and such circuits can be substituted for the full wave bridge rectifiers shown. 
     The output voltages of each of the full wave bridge rectifiers  52  lead to the display driver  22 . Previously in FIG. 4, a display driver was shown that was capable of producing twelve alpha-numeric characters. In FIG. 5, the display driver  22  is capable of producing only three alpha-numeric characters because the elevator system only has three floor levels. In FIG. 5, the first row of the display driver is configured to produce the letter “L” on a seven segment display  12 . The second row of the display driver is configured to produce the number “2” on a seven segment display  12 . Lastly, the third row of the display driver  22  is configured to produce the number “3” on a seven segment display  12 . 
     The display driver.  22  has seven outputs so as to drive a seven segmented display  12 . The outputs of the display driver lead into a power conditioning circuit  30 . In the shown embodiment, the power conditioning circuit utilizes a zener diode  32 , a plurality of resistors  34  and dip switches  36  in series with each of display driver outputs. The zener diodes are illustrated within the a seven segmented display  12  but should be considered part of the power conditioning circuit  30 . The dip switches  36  change which of the resistors  34  are in series with the outputs of the display driver  22 . The resistors  34  have different resistance values. As such, by using the dip switches  36 , a resistor can be selected that reduces the voltage of the display signals into the operational range of the seven segment display  12 . Consequently, by altering the dip switch settings, the system can be altered to operate within a wide range of supply voltages. 
     The outputs of the power conditioning circuit  30  lead into the seven segment display  12 . The seven segment display  12  produces an “L”, “2” or “3” depending upon the location signal received by from the elevator&#39;s systems controller. 
     In the schematics shown in FIG.  4  and FIG. 5, it appears that the various diodes  28  in the display drive circuit  22  are hard wired to the vertical lines  24  (FIG. 4) and horizontal lines  26  (FIG.  4 ). This need not be the case in all applications. Referring now to FIG. 6, a segment of a display drive circuit  22  is shown having vertical lines  24  and horizontal lines  26 . Each and every horizontal line  26  is interconnected to each and every vertical line  24  through use of a junction line  60 . A diode plug connector  62  is disposed within each junction line  60 . The diode plug connectors  62  are sized to selectively receive and retain a diode  28 . When no diode is present in a diode plug connector  62 , no current flows through the junction line  60  that supports that diode plug connector. However, when a diode  28  is present within the diode plug  60 , current flows through both the junction line  60  and that diode  28 . 
     As such, it will be understood that by selectively placing different diodes.  28  into different diode plug connectors, a technician can customize the display driver circuit to produce a wide variety of different alpha-numeric characters in response to different incoming signals from the elevator&#39;s systems controller  16  (FIG.  4 ). 
     The present invention elevator position indicator can be used in a wide range of voltages and in applications with either alternating current or direct current. The elevator position indicator uses commonly available parts. As such, the elevator position indicator can be manufactured very inexpensively and can be readily repaired. 
     It will be understood that the specifics of the elevator position indicator described above illustrates only exemplary embodiments of the present invention. A person skilled in the art can therefore make numerous alterations and modifications to the shown embodiment utilizing functionally equivalent components and circuit layouts to those shown and described. All such modifications are intended to be included within the scope of the present invention as defined by the appended claims.