Patent Publication Number: US-2004045380-A1

Title: Display for process transmitter

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to equipment used to monitor and control industrial processes. More specifically, the present invention relates to displays for transmitters which are used to measure process variables of an industrial process.  
       [0002] Industrial processes are used to monitor and control process fluids such as for manufacturing or refining. Example industrial processes include oil refineries, food manufacturing plants, paper pulp preparation facilities, and many others.  
       [0003] In industrial processes, it is often necessary for an operator to obtain information regarding the operation of the process. Remote units, known as “transmitters,” are coupled to the process and transmit information related to process variables (pressure, temperature, flow rate, etc.) to a control room. The process variables can be viewed or operated upon with equipment in the control room.  
       [0004] In some instances, it is desirable for an operator to view information from a process transmitter directly. Therefore, some process transmitters include displays which are used to directly display the measured process variable or other information related to the transmitter on a face of the transmitter. For example, an operator can use the display to calibrate or configure the process transmitter.  
       [0005] Although process transmitters have many physical configurations, a common design includes a housing having a process coupling side or a process couple face and a cylindrical cavity which houses various transmitter circuitry. The cylindrical housing arranged perpendicular to the process coupling face and is sealed with end caps which screw into each end of the cylinder. When a display is added to such a transmitter, it is typically located near one of the end caps. The end cap can have a clear window such that the display can be viewed externally. The display itself is typically rectangular and is placed squarely on the transmitter housing, i.e., it is oriented such that the long sides of the rectangular display are parallel to a width of the transmitter and the short sides are parallel to a height. Information is then displayed in a standard fashion across the width of the rectangular display, with the displayed characters and symbols aligned with the sides of the display.  
       SUMMARY OF THE INVENTION  
       [0006] A transmitter for use in a process control system for monitoring an industrial process includes a housing having a top and a bottom and a height extending therebetween. A process variable sensor is configured to sense a process variable of the process and provide a process variable output to transmitter circuitry which provides a display output. A parallelogram display is mounted to the housing with sides of the parallelogram display at angles relative to the height of the housing. In another aspect, characters are aligned at an angle with a parallelogram display. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a side plan view of a transmitter including a prior art display.  
     [0008]FIG. 2 is a side plan view of a transmitter including a display in accordance with an example embodiment of the present invention.  
     [0009]FIGS. 3A and 3B are side plan views of the display of the display of FIG. 2 and illustrates the display of different types of information.  
     [0010]FIG. 3C is a front plan view of the display showing segments of the display.  
     [0011]FIG. 4 is an exploded perspective view of a transmitter including the display of FIGS. 3A through 4. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0012] The present invention includes a process control transmitter having a display which is angled relative to a height and a width of a transmitter. This configuration allows additional information to be shown across the display. In one aspect, an angled parallelogram display is configured to display characters or data in a horizontal and/or vertical direction. As the display is angled relative to the transmitter height and width, the horizontal and vertical directions form an angle with sides of the display which is between 0 and 90°. In one specific embodiment, the angle is about 45°. In one aspect, a parallelogram display is provided in which characters on the display are angled relative to sides of the display.  
     [0013]FIG. 1 is a side plan view of a prior art transmitter  10  for use in a process control system for monitoring an industrial process. Transmitter  10  includes a housing  12  which couples to process piping  16  to a process coupling  14 . Housing  12  extends in a height direction H which is a direction away from the process coupling  14 . A width direction is perpendicular to the height direction.  
     [0014] As illustrated in FIG. 1, transmitter  10  includes a display  20 . Display  20  is a rectangular display which is arranged squarely with the height and width directions i.e., the short sides of the rectangle of the display are oriented parallel with the height direction and the long sides of the rectangle are oriented perpendicular to the height direction. Further, the characters on display  20  are also aligned with the sides of the rectangle. Frequently, LCDs (liquid crystal display) are used in which information is conveyed by activating elongate liquid crystal segments. Although displays which use segments are limited in the types of graphics and characters which can be displayed, a display with seven segments can be arranged such that all numbers can be illustrated. Further, a display with fourteen segments can be used to display alphabetical characters in addition to numeral characters. More complex graphics can be displayed using a matrix of dots.  
     [0015]FIG. 2 is a side plan view of a transmitter  40  in accordance with one embodiment of the present invention. Transmitter  40  includes housing  42  and process coupling  44  which couples to process piping  16 . In the arrangement shown in FIG. 2, a parallelogram display, specifically a display  50  is oriented such that sides of the square or rectangular display are at an angle to the height direction of the transmitter. In one embodiment, the rectangle comprises a square and the sides are all at a 45° angle to the height and width directions of transmitter  40 . Further, characters on the display  50  may be arranged at an angle relative to the sides of the display. In this embodiment, the angle of some of the characters relative to the sides of the display  50  are the same as the angle of the sides of the display  50  relative to the height and width directions of the transmitter  40  such that the characters aligned in a direction perpendicular to the height direction. When using a segmented display, many of the segments which are used to form numbers are oriented perpendicular to and parallel with the height direction.  
     [0016] Although the present invention includes a display which is a parallelogram, in one preferred embodiment, both sides of the parallelogram are parallel to thereby form either a rectangle or a square. Although a rectangular (specifically a square) display is shown, in one aspect parallelogram displays can be used.  
     [0017]FIGS. 3A and 3B are front plan views of display  50  showing different types of display information. Display  50  is shown with a graphical display  52  which comprises a bar graph oriented around a top corner  64  of the parallelogram. It is appreciated, that by following the angles of the parallelogram, efficient use is made of the display area. Alphanumeric information  54  is also shown on the display  50 . The alphanumeric information  54  is arranged at an angle relative to sides  56  of the display. In this embodiment, the alphanumeric information is at an angle of 45° to each of the four sides  56  of display  50 . The display  50  has a height H and a width W and the alphanumeric information is aligned parallel with the width W and perpendicular to the height H. The alphanumeric information is formed using elongate display segments, for example, liquid crystal segments. For those liquid crystal segments used to display numerical information, the segments are aligned parallel to either the width or the height of the display  50 . As used herein, a “character axis” is the axis along which characters are aligned, such as parallel to the width or height directions. This configuration allows information to be displayed between two opposed corners  60  and  68  of the parallelogram display. With such a configuration, relatively large alphanumerics or other information can be displayed between the two opposed side corners  60  and  62 . Information can further be shown in a smaller form in a top corner  64  and a bottom corner  66  of the display  50 . It is appreciated that some characters may be parallel to the width of the display while other characters may follow the sides and/or angles of the display (i.e., the bar graph shown in the top corner) or otherwise be arranged at any desired angle to better utilize the display area.  
     [0018]FIG. 3C is a front plan view of display  50  showing various characters and display segments. Display  50  includes a numeric display portion  80  which consists of seven separate seven segment display elements and adjacent periods arranged across opposed corners of display  50 . Also illustrated in FIG. 3C are alphanumeric portions  82  which comprise a row of five and a row of six separate fourteen segment display elements arranged across the width of display  50 . Fixed display elements  84  are also shown in FIG. 3C. In this example, they include the square root sign, a minus sign, the percent sign, and the word “ERROR.” The present invention can include other display configurations and formats. In one embodiment, the present invention is implemented using liquid crystal or light emitting diode elements. However, any display technology can be used. Although display  50  is shown including segments and fixed display elements, the display of the present invention can also comprise individual dots to form a dot matrix or other display techniques. A dot matrix display provides more flexibility in that the dots can be arranged to display any desired character.  
     [0019]FIG. 4 is an exploded view of transmitter  40  showing the various components which are carried inside housing  42 . Housing  42  includes a cylindrical section  90  which is sealed by end cap  92  and  94 . Within cylindrical section  90  is transmitter circuitry  100  and terminal block  102 . Transmitter circuitry  100  is configured to couple to a process variable sensor  104 . Sensor  104  can be located internal to housing  42  or externally. Process variable data from sensor  104  is received by transmitter circuitry  100  and coupled to a two-wire process control loop  110  through a terminal block  102 . Process control loop  110  couples to a control room  112 . Process control loop  110  can be in accordance with any appropriate technique or standard. For example, in one preferred embodiment loop  112  comprises a two wire process control loop which carries a current level of the between 4 milliamps and 20 milliamps. In some embodiments transmitter circuitry  100  including display  50  is completely powered with power received over loop  110 .  
     [0020] Display  50  can be configured to snap into circuitry  100  using tabs  120  which mate with receptacle tabs  122 . An electrical plug on display  50  plugs is received by circuit plug  124 .  
     [0021] The angle design of the display of the present invention allows for increased usability of the glass area of a display, especially the center set of characters which extend across the width of the display. Other techniques can also be used to increase the display area such as using a round display. However, these are more difficult to obtain or fabricate and therefore more expensive. Electrical contacts for coupling to such displays can also be problematic. In the specific embodiment set forth herein, there are about  240  segments to the display which require  42  electrical contacts which are spaced along two sides of the glass used for the display. The use of the rotated display is relatively inexpensive and provides a sufficient number of contacts along the edges for display of the desired information.  
     [0022] Although the display of the present invention is shown with a particular transmitter configuration, the display can be used with other process control instrumentation (including any process device which is located in the field such as control elements) in which it is desirable to display information. The invention efficiently utilizes the space available on the face of the instrumentation. External space for displaying information on a process device is limited. The invention allows additional data to be displayed, or to be displayed in a more readable format, then in typical prior art designs. Although a parallelogram and specifically a square configuration are illustrated, the present invention can be used with other configurations including rectangles. It is further appreciated that the parallelogram display does not require rounded or curved corners (such as in circular displays). Such rounded or curved corners are difficult to manufacture and increase manufacturing costs.  
     [0023] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. The sensor and/or display can be located remotely to the transmitter or transmitter circuitry.