Abstract:
An electrical test instrument includes an improved operator interface capable of including the following features: (i) a pause/prompt feature enable prompts to be displayed during a pause, in order to facilitate operator reconfiguration of the instrument during testing; (ii) an autocalibration alert function to alert the operator that the instrument requires calibration; (iii) a security function that enables the operator to select from among a plurality of security level options; and (iv) a more flexible menu structure that enables set-up of additional tests performed by plug-in test instrument modules.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrical test equipment, and in particular to an electrical safety compliance test instrument having an improved operator interface. 
     The electrical safety compliance test instrument of the invention includes a number of improvements designed to simplifying set-up and testing procedures, in order to reduce the risk of operator error and to ensure accurate test results. The improvements utilize a softkey controlled display screen capable of displaying a complete safety test instruction set or set of test parameters, and/or a complete set of test results, to provide the following interactive display functions or features: 
     a pause/prompt function that causes prompts to be displayed during a pause, in order to facilitate operator reconfiguration of the equipment during testing; 
     an autocalibration alert function that alerts the operator when the instrument is due for scheduled calibration; and 
     a security function that enables the operator to select from among a plurality of security level options 
     a more flexible menu structure that enables set-up of additional tests performed by plug-in test instrument modules. 
     2. Description of Related Art 
     Electrical safety compliance test equipment has become increasingly sophisticated or complex, both to meet the requirements of different agencies responsible for safety compliance testing, and also because of the availability of improved microprocessor based controllers which enable a single tester to perform multiple tests based on pre-programmed instruction sets. As a result, demands on the operator of the equipment have also increased. In order to perform the multiple tests that might be required for a particular product, the operator must not only correctly program all of the numerous test parameters for each of multiple steps, but also must, during testing, correctly connect and then reconfigure the connections between the test equipment and the device undergoing the tests. Often, the same equipment is used to test different types of products, each requiring different sets of tests or testing procedures, or to test products for shipment to different countries with varying test requirements. Because many of the tests are performed at voltages in excess of 1000 volts, incorrect connections can present a serious safety hazard to the operator or bystanders, while improper test set-up or interpretation of the test results can result in the shipment of defective products and hazards to consumers. 
     An example of the trend toward greater test instrument sophistication is the multiple function dielectric withstand tester described in U.S. Pat. No. 6,054,865, assigned to Associated Research, Inc. of Lake Bluff, Ill., which is capable of performing at least five different types of tests. The tests, which include high voltage AC and DC dielectric withstand tests, insulation resistance tests, AC ground bond tests, and DC continuity tests, all require different connections between the tester and the device under test, and therefore a highly skilled operator. In addition, the Associated Research multiple function dielectric withstand tester has the capability of being linked to additional safety testers of different types, further complicating test set-up and interpretation. 
     Another example of a tester capable of performing different types of tests with multiple test configurations is the line leakage tester disclosed in U.S. Pat. No. 6,011,398, also assigned to Associated Research, Inc. This tester has the capability of running multiple tests to simulate different potential hazards that might be faced by a user of the product being tested, and like the Associated Research multiple function dielectric withstand tester, also includes external link capabilities. 
     To simplify test set-up and minimize risk of operator error, both of the Associated Research testers provide an integrated menu-driven user interface for setting-up multiple pre-programmed test sequences. For example, the operator interface of the electrical safety compliance test instrument illustrated in FIG. 1, which is identical to the instrument illustrated U.S. Pat. No. 6,054,865, includes a keypad  1  made up of a plurality of pre-assigned function keys  2  and a numeric keypad  3 , various LED indicators  4 , 5  and an LCD display screen  6  capable of displaying interactive menus through which test parameters such as voltage and current levels, test duration, and ramping times, may be preprogrammed or set for each of the types of tests that the instrument is capable of carrying out, as well as an on/off switch  7 , start button  8 , reset button  9 . Also included on the front panel of the illustrated multifunction dielectric withstand test instrument are respective high voltage, current and return jacks  10 , 11 , 12 . 
     By providing integrated, menu driven operator interfaces, the test instruments described in the Associated Research patents, including the test instrument illustrated in FIG. 1, reduce the chance of operator error and thereby offer significant safety and convenience advantages over conventional non-interactive instrument displays. Nevertheless, the operator interfaces of the two testers, as well as those of other safety compliance test instruments, still place relatively high demands on the operators, with consequent hazards to both the operator and end-users of the product being tested. 
     In order to eliminate any possible source of operator error, it has been proposed in U.S. Pat. No. 5,861,882 to completely automate the process of test configuration, using software-based switches to switch between multiple test instruments and an icon based interactive test set-up and control display. While this approach has the advantage of ease-of-use, the icon based control is designed to be implemented on a central computer linked to separate test instruments and is not suitable for implementation through a display integrated into the front panel of a single instrument, the separate test instruments being connected via a common bus to the central computer and via a single pre-configured interface to the device under test. The configuration of the interface to the device under test is not specifically described in U.S. Pat. No. 5,861,882, but rather is presumed to be constant, with no provision for automatic switching or re-connection of test probes, or for programming of individual test instruments to cooperate with the main control program and accept the appropriate test commands. To the contrary, as explained in the abstract of U.S. Pat. No. 5,861,882, the test instrument of this patent seeks to dynamically reconfigure the test set up for different tests without hand rewiring or loading of other test programs, thereby both increasing the complexity of the system and in practice greatly limiting the number of different types of tests that can be performed with a particular instrument. This lack of provision for reconfiguration of instrument to device under test connections makes the system described in this patent impractical for many safety compliance testing applications. 
     Unlike the operator interface described in U.S. Pat. No. 5,861,882, which is designed to control separate test instruments connected by a common bus to a pre-configured connection to the device under test, the present invention concerns an operator interface integrated into a single multiple function test instrument. In the context of single instrument operator interfaces, it is of course known to provide displays that provide multiple lines of text as well as graphics, but none of these single-instrument displays address the above-described concerns related to electrical safety compliance testing. 
     An example of a prior text/graphic display capable of displaying large amounts of information is the medical diagnostic instrument display disclosed in U.S. Pat. No. 5,056,059. While the display screen disclosed in this patent could be included in a multiple function safety compliance test instrument, however, the software that controls the display is not suitable for use in a safety compliance tester because of the limited number of probe configurations and types of tests that can be controlled by the instrument, and the higher level of training required to operate the instrument. 
     Another type of instrument with an operator interface that utilizes a sophisticated text/graphics display is the communications line test device disclosed in U.S. Pat. No. 5,808,920. The test device disclosed in U.S. Pat. No. 5,808,920 is arranged to enable input and interpretation of digital communications protocols, however, and therefore does not require the multiple test lead configurations or high voltages of safety compliance test instruments. 
     Also of interest by way of background are voltage-current multimeter displays, such as the one disclosed in U.S. Pat. No. 6,064,372, which eliminates the need for multiple buttons by including a touch screen, and oscilloscope displays, such as the one described in U.S. Pat. No. 5,321,420, which is of particular interest because it includes a softkey control rather than a scrolling or purely graphical display. While multimeters and oscilloscopes both perform numerous types of electrical tests, however, neither utilizes pre-programmed test sequences of the type included in the above-described safety compliance testers, and thus the operator interfaces used in such electrical testers are not suitable for use in safety compliance testers. 
     Those skilled in the art will appreciate that the displays disclosed in the above-mentioned patents are both more sophisticated than those of conventional safety compliance testers, and yet are not suitable for use in such testers because of the lack of provision for pre-programmed test set-ups, and other features unique to safety compliance testing. The present invention, on the other hand, occupies a middle ground between the multiple instrument graphical user interface described in U.S. Pat. No. 5,861,882 and the scrolling displays integrated into the Associated Research test instruments disclosed in U.S. Pat. Nos. 6,054,865 and 6,011,398, or the test instrument disclosed in U.S. Pat. No. 5,101,160, which like the displays described in the Associated Research patents, includes a scrolling test mode alphanumeric display (col. 7, lines 7-12) and a code key lockout feature (col. 7, lines 47-50). In particular, without requiring a separate computer and graphical user interface as in U.S. Pat. No. 5,861,882, the present invention address problems unique to electrical safety testing that cannot be addressed by the limited displays of conventional instruments, including the following: 
     Because of the limited size of the conventional safety compliance test instrument display screen, only one step or set of parameters can be presented at one time, making it difficult and relatively time consuming to input and verify an entire test setup, and to read the results of a test. 
     Although a number of currently available testers provide for pre-programming of multiple test set-ups, it is still necessary to manually reconfigure connections to the device under test, during which improper connections can occur. 
     Improper test results and possible hazards to the operator can result from failure to calibrate the instrument regularly. 
     While prior safety compliance test instruments include lockout features for preventing unauthorized use of the instrument, the conventional lock-out arrangements lack the flexibility to permit access to selected test set-ups but not others, or to limit changes to certain parameters or features. 
     In summary, despite the importance of electrical safety compliance testing and the availability, in other contexts of suitable displays, no safety compliance instrument to date has addressed such concerns as the need to provide operator prompts that ensure proper manual reconfiguration by the operator of test set-ups during testing, timely calibration of the instrument, or the ability to select from among a plurality of security level options. What is needed is an operator interface including a display suitable for integration into a safety compliance test instrument that provides clear instructions on carrying out a test, including instructions on reconfiguration of the connections to the device under test, as necessary, and that ensures that the instrument is properly calibrated and ensures access only to operators qualified to perform particular tests greatly enhances the safety of the testers. 
     SUMMARY OF THE INVENTION 
     It is a accordingly a first objective of the invention to provide a safety compliance test instrument having an improved operator interface that minimizes risk of operator error during set-up and running of multiple tests, and of errors in reading or interpreting test results. 
     It is a second objective of the invention to provide a safety compliance test instrument having an improved display enabling verification at a glance of entire test sequences, sets of test parameters, and test results. 
     It is a third objective of the invention to provide a safety compliance test instrument having an improved display that minimizes risk of operator error by providing prompts during pauses for operator reconfiguration, instructions on re-positioning or change of test leads, and on interconnection of multiple test instruments of different types. 
     It is a fourth objective of the invention to provide a safety compliance test instrument that reduces risks associated with miscalibration by providing a warning that scheduled calibration is required. 
     It is a fifth objective of the invention to provide a test instrument with enhanced security features, including the ability to allow an operator to not only select a password to access system set ups, but also to enable restriction of users to partial recall of test set ups or only the test and reset functions, allowing better control and monitoring of tests and test results. 
     It is a sixth objective of the invention to provide a test instrument having a more flexible menu structure that enables set-up of additional tests performed by plug-in test instrument modules 
     These objectives of the invention are achieved, in accordance with the principles of a preferred embodiment of the invention, by providing a safety compliance test instrument with a large display, soft key controls, a pause/prompt feature that enables display of instructions for re-configuring or changing test leads during pauses between tests, a calibration warning feature that warns the operator a predetermined time before calibration of the test instrument is required, and an enhanced security feature that enables input and display multiple lockout levels. 
     The pause/prompt, calibration warning, and enhanced security features of the preferred embodiment of the invention are each preferably accessed through softkey-controlled submenus that permit entry, respectively, of messages to be displayed during pauses in execution of control programs, a calibration alert toggle setting and number of days before calibration that the alert is to appear, and a security activation toggle setting, password entry, and security level toggle setting. 
     In a particularly preferred embodiment of the invention, the test instrument is a multifunction safety compliance tester of the type disclosed in U.S. Pat. No. 6,054,865, which is capable of performing insulation resistance and ground circuit tests as well as high voltage AC and DC dielectric withstand or hipot tests, and which is further arranged to receive plug-in test instrument modules that permit additional tests to be performed by the safety compliance instrument, the menu structure permitted by the preferred display enabling set-up of the additional tests performed by the plug-in test instrument modules through a single integrated menu-driven control input. 
     Although a particular type of safety compliance test instrument is described in detail herein, those skilled in the art will appreciate that the principles of the preferred embodiment of the invention may be applied to line leakage testers, run testers, and a variety of other test instruments capable of running multiple pre-programmed test sequences requiring multiple test lead configurations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation of the multifunction safety compliance tester described in U.S. Pat. No. 6,054,865. 
     FIG. 2 is a front elevation of the safety compliance test instrument and improved operator interface of the preferred embodiment of the invention. 
     FIG. 3 is a block diagram illustrating principal components of the multifunction safety compliance test instrument illustrated in FIG.  3 . 
     FIG. 4 is a block diagram illustrating a menu hierarchy for the display controller of the preferred embodiment of the invention. 
     FIGS. 5,  6 ,  7 ( a )- 7 ( f ), and  8 ( a )- 8 ( b ) are illustrations of various menus and submenus referred to in the block diagram of FIG.  4 . 
     FIG. 9 is a flowchart illustrating a method of implementing the safety compliance instrument operator interface of the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 illustrates the front panel of a safety compliance instrument having an improved operator interface arranged, according to the principles of a preferred embodiment of the invention, to include a display screen  20  capable of enabling operator control of such features as a calibration alert function, an improved security function, and a “prompt feature.” These features are accessed through softkey-controlled pages or sub-menus that appear on the screen  20  of the safety compliance test instrument, the illustrated safety compliance test instrument operator interface including six softkeys  1 - 6 , a standard numeric keypad  7  including up, down, left, and right cursor control keys  8 , an “enter” or “input” key  9 , and an “exit” key  10 . 
     The test instrument illustrated in FIG. 2 is a type of safety compliance tester known as a “hipot” or dielectric withstand tester, which applies a high DC or AC voltage to a product and monitors for leakage currents in order to test whether insulation in the product can withstand the voltage. As a result, the front panel of the illustrated test instrument includes, in addition to the operator interface, on/off, test, and reset switches  11 , 12 , 13  and high voltage, current, and return jacks  14 , 15 , 16 . As a result of the improved display screen, the illustrated test instrument does not require any LED indicators corresponding to LEDs  104  shown in FIG. 1, but the interface does include LED indicators  17  which are used to show the progress of an optional scanning function. 
     Aside from the improved operator interface, the safety compliance test instrument illustrated in FIG. 2 is identical to the test instrument described in U.S. Pat. No. 6,054,865, herein incorporated by reference. Because the test circuitry is essentially the same as that described in U.S. Pat. No. 6,054,865, and because the present invention relates to an operator interface or display system and not to particular test circuitry, the test circuitry is not described in detail herein. Instead, the operator interface of the invention should not be limited to a particular safety compliance test instrument, but rather may be applied to a wide variety of safety compliance test instruments utilizing numerous different hardware configuration. Nevertheless, FIG. 3 shows that the circuitry of the preferred test instrument may include a main controller  21  corresponding generally to the controller described in the U.S. Pat. No. 6,054,865, test circuitry  22  made up of power conditioning, rectifier, amplifier, and protection circuits as necessary to enable the desired tests to be performed on device under test  23 , and an interface  24  for establishing a connection to a plug-in test instrument module  25 . Test module  25  may include a line leakage test module, a run test module, and/or a matrix scanner. In addition, the preferred test instrument may include a keypad control board  26  and a display screen controller  27 . The screen controller  27  may be in the form of a separate microprocessor connected to the main controller  21  and to the keypad control board  26 , or it may be integrated into the main controller and possibly share a microprocessor. 
     Those skilled in the art will appreciate that numerous display control microprocessors are currently available for controlling the display and carrying out the desired display functions, as described in more detail below, and that the invention should not be limited to a particular circuit configuration or microprocessor arrangement. 
     Unlike the multiple function high voltage test instrument illustrated in FIG.  1  and described in the U.S. Pat. No. 6,054,865, the multiple function test instrument of the preferred embodiment of the invention includes an enlarged screen capable of displaying multiple lines of text and, optionally, graphical elements. Although the illustrated display screen is a 320×240 monographic liquid crystal display (LCD), the display screen  20  may alternatively be in the form of a color liquid crystal display, cathode ray tube (CRT), or any other display screen capable of displaying the menus and submenus described below, while the softkeys  1 - 6  are assigned to a memory location or register whose function depends on the menu displayed on the screen, as will be described in more detail below. Operation of softkeys is well-known in connection with displays other than those used in electrical safety compliance test instruments or equipment, as described, for example, in U.S. Pat. No. 5,321,420, herein incorporated by reference. 
     FIG. 4 is a flowchart of the various menus and submenus used to implement the enhanced operator interface of the preferred embodiment of the invention, with details of the menus and submenus being illustrated in FIGS. 5,  6 ,  7 ( a )- 7 ( f ) and  8 ( a )- 8 ( b ). The main menu  30 , as illustrated in FIG. 5, utilizes softkeys  2 - 4  to enable access respective submenus  31 - 33  for enabling, respectively, setup or programming of system or instrument parameters, setup of individual tests, and running of individual tests. The security and calibration features are accessed through the setup system submenu  31 , illustrated in FIG. 5, while the pause/prompt feature is accessed through the setup tests submenu, illustrated in FIG.  6 . 
     Selection of the “setup system” submenu  31 , as illustrated in FIG. 5, presents the operator with five options, selected through softkeys  1 - 5 , including time and date entry, instrument identification, general parameters of the system such as alarm volume, display screen contrast, optional scanner selection, selection of a “smart” ground fault interruption (GFI) feature and the option of connecting the return jack  16  to ground. Those skilled in the art will of course appreciate that other options and features may also be accessed from this submenu, as well as from the submenus described below, and that on the other hand any of the functions or features illustrated in FIG. 5 may also be omitted or replaced depending on the requirements of the instrument in which the preferred operator interface is installed. 
     In the preferred embodiment of the invention, the calibration alert feature is accessed through an “instrument ID” submenu  34  which displays the model and serial numbers of the instrument, and a calibration due date. By means of this submenu, the operator is respectively presented with the option of toggling the calibration alert function between “off” and “on” using softkey  3 , of inputting the number of days before the calibration due date to issue a warning using softkey  4  and the numeric keypad, and of entering a GPIB address using softkey  6  and the numeric keypad if an GPIB interface card has been installed. When the calibration alert function is toggled to on, the display will present a warning that the calibration due date is approaching a selected number of days before the actual due date, in order to ensure that the instrument is kept properly calibrated both for reasons of safety and also to ensure accurate test results. 
     The password protection feature is implemented using the security submenu  35  of the setup system menu  31 . In this submenu, softkey  1  is used as a toggle to activate the feature, softkey  2  enables entry of a password using either the numeric keypad or a letter selection menu (described below in connection with the pause/prompt feature), and softkey  3  toggles a file recall function which provides the option of allowing the system to be set up to afford a user access to full setup, partial recall of test setups, or to prevent access to the menu display functions, leaving only the TEST and RESET functions accessible through buttons  13  and  12 . Preferably, the display will present a lockout status message so that users will immediately know that they have attempted to access a restricted mode. 
     The prompt feature is accessed using the setup tests menu  32 , shown in FIG. 6, which includes a listing of tests that have already been pre-programmed and that may be selected using the cursor control keys  8 . The setup tests menu includes an “add” option (softkey  1 ), which invokes a modified setup tests menu  32 ′ that lists tests that have not already been set up (in the illustrated example, the new tests are an AC ground bond test and a DC continuity test), and an “edit” option (softkey  2 ). Selection of the “add” option and a new test to be added, or selection of the “edit” option, calls up one of submenus  36 - 42 , one of which is shown in FIG.  6  and the remainder in FIGS.  7 ( a )- 7 ( f ) depending on the position of the cursor in the setup tests submenu  32  or the add tests version  32 ′ of the set up tests submenu. Also included in the setup tests menu  32  is a delete option, activated by softkey  3 , the aforementioned “prompt” function, activated by softkey  4 , which calls up a prompt submenu  45  also shown in FIG. 6, a file function which enables naming and saving of setup test files using an appropriate files submenu (not shown), and a fail stop option toggle for the test indicated by the current cursor position. 
     The setup tests submenus for the individual tests all include parameter inputs appropriate for the individual tests that the instrument is equipped or configured to perform. In the case of the AC withstand test menu illustrated in FIG. 6, the parameters that many be input using cursor keys  8  include the test voltage, upper and lower current limits, ramp-up, dwell, and ramp down times, and so forth, while softkeys  1 - 4  and  6  toggle various additional options, including frequency and a default settings option. All of the individual parameters and features of the respective setup test submenus illustrated in FIGS.  6  and  7 ( a )- 7 ( e ), including respective setup test submenus  36 , 37  for AC and DC dielectric withstand tests, submenu  38  for setting up an insulation resistance test, submenu  39  for setting up a DC continuity test, submenu  40  for setting up a ground bond test, and submenu  41  for setting up a line leakage test performed by a plug-in test instrument module, are described in detail in U.S. Pat. Nos. 6,054,865 and 6,011,398, and will be familiar to those skilled in the art, or at least to owners of commercially available Associated Research multiple function safety compliance instruments. The submenu  42  illustrated in FIGS.  7 ( f ) is for an optional run test capability, and includes high and low voltage and current settings, dwell and delay time settings, high and low leakage current limit settings, high and low power limit settings, and high and low power factor limit settings. 
     The “prompt” menu  45 , which is displayed upon pressing of softkey  4  during display of the setup tests menu  32 , includes a display of alphabetic characters that may be selected, together with numbers on the numeric keypad  7 , to form a message using cursor keys  8  and respective select and delete softkeys  1  and  2 . The message is displayed during a pause following the test indicated by the cursor position in setup tests submenu  32 , and therefore may include reminders and instructions concerning activities to be carried out by the operator during the pause, include instructions on connections to the device under test, or messages concerning safety or interpretation of test results. 
     The final submenu called up from the main menu  30  is the perform tests submenu  33 , which enables test files to be selected using the cursor keys  8 , files to be loaded using softkey  1 , single step and fail stop options to be selected using softkeys  2  and  3 , and results to be called up for a previously run test using softkey  4 . Upon completion of a test, the results for a particular test many be displayed on a window or portion  33 ′ of the perform tests submenu display screen. When the “results” option is selected, a display of all of the results of a complete test run can be displayed on a single screen (not shown), additional details of fewer than all of the tests may be displayed, or the results of just a single test may be displayed. 
     FIG. 9 illustrates a method of presenting the submenus corresponding to the calibration, security, and pause/prompt features of the preferred embodiment of the invention. Following display of the main menu  30  (step  40 ), the display controller waits for a softkey to be pressed (step  41 ). If softkey  2  is determined to be pressed (step  42 ), then the setup system menu is displayed (step  43 ). If softkey  2  is then determined to be pressed (steps  44  and  45 ), the instrument ID menu is displayed (step  46 ), after which if softkey  3  is determined to be pressed (steps  47  and  48 ), the calibration alert function is toggled to on (step  49 ), while if softkey  4  is determined to be pressed (step  50 ), the controller waits for a numeric input of the days-to-warn function (step  51 ). On the other hand, if softkey  5  is determined to be pressed while displaying the setup system menu (step  52 ), the security menu is displayed (step  53 ), and if respective softkeys  1 ,  2 , or  3  are determined to be pressed (steps  55 - 57 ), the security feature is toggled (step  58 ), the controller enables entry of a password (step  59 ), or the file recall function is set (step  60 ). Finally, if softkey  3  is pressed while the main menu is being displayed (step  61 , the setup tests menu is displayed (step  62 ), and if softkey  4  is pressed from the setup tests menu (steps  63  and  64 , the prompt menu is displayed (step  65 ), after which the display controller enables entry of the prompt message (step  66 ). 
     It will of course be appreciated by those skilled in the art that the steps illustrated in FIG. 9 are not exclusive, and that the functions and features of the preferred embodiment of the invention may be carried out in different orders using variations of the menus and submenus illustrated in FIGS. 5,  6 ,  7 ( a )- 7 ( f ), and  8 ( a )- 8 ( b ), that functions and features may be added or deleted, and that details of the functions and features described above may be varied depending on the nature of the safety compliance tests to be carried out by the safety compliance instrument to which the operator interface of the invention is applied. 
     As a result, although a preferred embodiment of the invention in sufficient detail to enable those skilled in the art to make and use the invention, it will nevertheless be appreciated that numerous variations and modifications of the illustrated safety compliance instrument and operator interface therefor may be made without departing from the spirit of the invention. As a result, it is intended that the invention not be limited by the above description or accompanying drawings, but rather that the invention be defined solely in accordance with the appended claims.