TEST METERS

Abstract: The present invention relates to a test meter (10) for testing an electrical circuit or component for one or a plurality of parameters. The test meter (10) comprises a microprocessor (500) programmed to receive signals from the remote (502) and local (504) switches generating a test format selection signal, sending the test format selection signal to the meter circuit (510) causing the meter (10) to operate in the selected format. A visual display (530) and/or speech synthesizer (540) will respectively display and/or audibly report the test results in the selected format.

Description: TEST METERS Field Of The Invention This application is a Continuation in Part of U.S. Serial No. 07/053,385 filed May 22, 1987 by MILTON BERNARD HOLLANDER and WILLIAM EARL Mc INLEY entitled TEST METERS. The present invention relates to test meters, parti¬ cularly of the type employed for testing an electrical circuit or component for one or a plurality of para¬ meters, e.g., multimeters; and provides improvements in meters of this type which greatly enhance their con¬ venience and their efficiency of use. Multimeters are well known in electronics, re¬ search, and trouble-shooting contexts for testing, typi¬ cally voltage, current and resistance with a single instrument. Often, meters of this type will further have temperature-sensing capability. These meters almost universally have a visual display for reporting test results and one or more switches on the meter for selecting the test parameter and scale range desired. Hand-held probes are typically employed for contacting a work piece at suitable test points. Unfortunately, where it is necessary to run a variety of tests, it is often inconvenient to set the probes down, change switch positions, and again place the probes in contact with the desired test points. It is also inconvenient at times for the operator to change his direction of view from the test points to the visual display. While meters with voice reporting are know, the reporting format will in many circum¬ stances detract from its apparent appeal. It would be advantageous to have a test meter which would overcome at least one of the noted disadvantages by enabling switching between a plurality of test or report formats without moving test probes from test points and/or enabling variations in the format of an audible report. Background Art In U.S. Patent 4,563,770, Lemelson and Grund dis¬ close an electrical measuring instrument, such as a multimeter, which enables the results of a measurement to be displayed visually as well as by synthesized speech. The meter includes an electrical circuit for the analyzing signals generated in making measurements to assure that no speech report is produced until the signals have stabilized. A foot-operated, normally- open switch permits the operator to trigger the opera¬ tion of the speech synthesizer when it is desired to generate audible synthetic speech, and also provides the operator with a means for repeating the most recent measurement in the event the operator did not properly hear the previous speech indication of the measurement. While an object of the invention is to enable blind per¬ sons to more easily employ the meter due to its speech report, the meter does not solve some of the more trou¬ blesome problems with meters with conventional visual displays, much less with speech reporting systems. Regardless of the means employed for reporting, be it visual or audible, test meters have the nearly uni¬ versal problem that the operator's hands and vision must usually give attention to the area of the test points. Often it is desired to switch among a plurality of test or report formats; however, there is no provision for such by the device of Le elson and Grund. For example, where the operator has both hands busy on a complex electrical workpiece and wishes to test resistance followed by voltage and then current, he must remove his test probes from the locale of the test points, manually reset the meter, and again find the test points. In U.S. Patent 4,604,569, Tedd and Kennedy describe a multimeter having two slide switches on the meter to control test format and an audible alarm to warn of incompatible settings to control test format. Each of the switches is set by the operator to control a dif¬ ferent measurement function. Where the operator makes a selection of two incompatible setting, a buzzer sounds. While this feature is advantageous, it re¬ quires manual setting of the switches and permits the incompatible settings to be made. It would be more desirable to have a meter which could be set from a remote location, e.g., at the location where the opera¬ tor is using his hands to perform the test of the cir¬ cuitry, and preferably to include circuitry which would not permit the incompatible test format to be selected and would audibly advise the operator of such by spoken word. In U.S. Patent 4,633,221, Bradshaw and Evans des¬ cribe a multimeter including a dual slope analog-to- digital converter having automatic short cycle range determination. The converter adjusts the time period of the signal integrate phase to accommodate different ranges of input signals. Range selection is achieved automatically and rapidly without the need for display¬ ing an out of range reading. While this appears to enhance the utility of typical autoranging meters, it would be desirable to have a meter which, preferably would permit selecting a desired test formal without the operator removing his hands or attention from his workpiece. It would be further desirable to have a meter of this type which would let the operator know in plain English or other language of choice, which test format, in terms of parameters and scale had been selected. Enabling a meter to report results as synthesized speech " is not a full answer to the problems with con¬ venience and efficiency of use. Simply verbalizing reports adds a drawback that, in many cases, much of the information is repetitive and need not be reported. For example, where a long series of tests of one para¬ meter is called for, it is not necessary to report that parameter in all instances and to report all decimal points placements. Often a format, which enabled once reporting the parameter being tested followed by a series of significant digit reports for each test point would not only be adequate, but be desired. And, under the circumstances of the present invention, where re¬ mote selection of test format, is available, it would be advantageous to enable an audible report of the test format selected. Disclosure Of The Invention It is a principal object of the present invention to provide a meter capable of testing at least one physical parameter and audibly reporting test information in a plurality of selectable formats. It is another principal object of the present inven¬ tion to provide a test meter having means for select¬ ing, from a position remote from the meter, between a plurality of test and/or report formats. It is a further object of the present invention to provide a test meter having at least one test probe which includes means for selecting among a plurality of test and/or report formats. It is another object of the present invention to provide a meter capable of testing at least one physi¬ cal parameter and reporting test information as syn¬ thesized speech in a plurality of selectable formats and which can be conveniently adapted to different languages. It is a more specific object of the present inven¬ tion to provide an electrical test meter capable of testing voltage, current, resistance and preferable temperature, and reporting test information, including test parameter, scale of values of sensed parameters, as synthesized speech in a plurality of selectable formats and further including means for selecting, from a point remote from the meter, between a plurality of test and/or report formats. It is a further object of the present invention to provide an electrical test meter capable of testing vol¬ tage, current and resistance and reporting test infor¬ mation such as test parameter, scale or sensed values. as synthesized speech in a plurality of selectable formats and further including at least one test probe which includes means for selecting from a plurality of test and/or report formats. These and other objects are accomplished according to the invention which provides several improvements. These improvements can be employed separately or in combination to enhance the convenience and efficiency of using a test meter in a variety of practical situations. According to one aspect of the invention, a test mete is provided which has a plurality of selectable test and/or report formats and comprises: selector means, operable responsive to a remote stimulus, for causing the meter to operate in a desired test and/or report format; means for contacting a test point and communicating a test signal to said meter, said signal being indicative of a value of a parameter at said test point; and means responsive to said signal for report¬ ing said value. The remote stimulus can be provided by means of, for example, electromagnetic radiation, a sonic signal or an electrical contact or proximity switch. Preferably, the means for contacting a test point comprises a contact probe configured for being held and positioned at a desired test point by hand and includes an electrical switch which is operable by hand while the probe is held in the locale of the test point. Most preferably, the probe will include two switch means operable by hand, one switch being coupled to said selector means to control test format and the other being coupled to said selector means to control report format. Desirably, the meter will include a visual display for reporting test results, and means for audible reporting test information comprising: means for storing a plurality of selectable report formats; a speech synthesizer; a microprocessor pro¬ grammed to direct a selected report format to be uti¬ lized by the speech synthesizer; and an amplifier and speaker to report test information as speech in the selected report format. According to another embodiment, the invention pro¬ vides a test meter capable of reporting test results as speech in any one of a plurality of selectable report formats, which comprises: means for receiving a test signal, and generating a meter output indicative of a measured value of a parameter, and directing said meter output to a microprocessor; means for storing a plura¬ lity of selectable report formats and directing a selec¬ ted one to said microprocessor; selector means for caus¬ ing a particular report format to be directed to said microprocessor; a speech synthesizer; and a micro¬ processor programmed to receive said meter output and cause the speech synthesizer to audible report test results in a selected format. As in the other embodi¬ ment, preferably the test meter will also include a visual display for reporting test results, and the selector means will be operable responsive to a remote stimulus. Preferably, the means for receiving test signals comprises a contact probe configured for being held and positioned by hand and includes an electrical switch which is operable by hand while said probe is held ' in contact with a desired test point. Most pre¬ ferably, two switches will be located on the probe and operable by hand, one switch being dedicated to control test format and the other being dedicated to control report format. According to one preferred embodiment of the inven¬ tion, the two principal aspects are combined to provide a multimeter which provides even further improved effi¬ ciencies and use of operation due to the enhanced abi¬ lity of the operator to interact with the meter with a minimum of required distractions. The multimeter ac¬ cording to this aspect of the invention comprises: selector means including a microprocessor, operably responsive to a remote stimulus as well as switching means on the meter, for causing the meter to operate in desired test and report formats; probe means for receiv¬ ing a test signal; an autoranging multimeter circuit capable of generating a meter output responsive to said test signal and indicative of a measured value of a parameter, and directing said meter output to a micro¬ processor; means for storing a plurality of selectable report formats and directing a selected one to said microprocessor; selector means for causing a particular report format to be directed to said microprocessor; a speech synthesizer; and a microprocessor programmed to receive said meter output and cause the speech synthe¬ sizer to audible report test results in a selected for¬ mat. According to still another embodiment in accordance with the invention a speaking multimeter is provided in which a main microprocessor controls its operation in¬ cluding automatic ranging, responding to probe inputs and servicing a display. A replaceable speech module is employed having a speech chip and a second micro¬ processor connected between the main processor and the speech chip. The main processor delivers meter data to the second microprocessor. This responds by sending command signals to the speech chip to cause it to speak the displayed meter data according to language rules programmed in the second processor. In this manner. the meter design can remain the same no matter where in the world it may be used while the speech module is altered to speak the local language. Brief Description Of Drawings The invention will be better understood and its ad¬ vantages will be more apparent from the following de¬ tailed description of Best Modes Of The Invention, es¬ pecially when read in light of accompanying drawings, wherein: Figure 1 is a perspective view showing the outward appearance of a multimeter according to the present invention; Figure 2 shows the detail of a female connector on the front panel of the multimeter for a specialized contact probe of the present invention; Figure 3 shows, in perspective, the detail of a male connector for mating a specialized contact probe of the invention with a meter by means of a female connector as shown in Figure 2; Figure 4 is a perspective view of a preferred em¬ bodiment of the invention showing a speaker at the rear of a multimeter; Figure 5 shows, schematically and partially in sec¬ tion, a foreshortened view of a specialized contact probe of the invention; and Figure 6 is a block diagram showing the arrangement of circuit components for a preferred embodiment of the invention. Figure 7 is a perspective view of another "speak¬ ing" test meter in accordance with the invention; Figure 8 is a rear end view of the meter of Figure 7; Figure 9 is a right side view in elevation of the meter of Figure 7; Figure 10 is a left side view in elevation of the meter of Figure 7; Figure 11 is a block diagram view of the electrical circuitry used in the test meter of Figure 7; Figure 12 is a flow chart of the operation of the main processor in the test meter of Figure 7; Figure 13 is a general flow chart of the operation of one speech module used in a test meter of this inven¬ tion; Figure 14 is a more detailed view for a flow chart for the speech module used in a test meter of this invention; Figure 15 is a listing of all data transferred from a main processor to a speech module used in the test meter of this invention; Figure 16 is a listing of words stored in digital format within a speech chip used in the test meter of this invention; Figure 17 is a more detailed flow chart of steps used in operating a speech module used in a test meter of the invention; and Figures 18-21 are flow charts used to speak measure¬ ments using respectively different radix routines. Best Mode Of The Invention The improvements provided by the invention can be employed in meters for testing one or a plurality of physical parameters. The meters can employ one or a plurality of contact probes or other sensors. The prac¬ tical significance of the advantages are, however, most easily appreciated in test meters having a plurality test or report formats which employ at least two con¬ tact probes. Accordingly, for ease in describing the invention, the various improvements will be explained in the context of an electronic multimeter capable of testing voltage, current and resistance. The meter shown in Figure 1 is a held-held meter of this type, and additionally has the capability of measuring tem¬ perature. The meter 10 shown in Figure 1, includes a housing 12 and is operable with two hand-held contact probes 14 and 16. Contact probe 14 is desirably the "cold" probe and will be contacted with the negative or ground test point, while probe 16 is desirably the "hot" probe and will be contacted with the positive test point. The term "test point" is used simply to identify any point on a circuit or component it is desired to test. Reference to Figure 5 shows probe 16 foreshortened and partially cut away to reveal the detail of construc¬ tion. Shaft 18 is constructed of a suitable plastic material and has a metallic contact 20 mounted at its front end. Contact 20 is adapted for electrical con¬ nection to the meter by means of conductor 22 and has a hollow interior which holds another sensor such as ther¬ mocouple 26, which can be of any suitable type and con¬ struction. Leads 28 and 30 extend from the thermo¬ couple 26 for connection to the meter. The probe 16 is also shown to include two switches 32 and 40 at least one of which, preferably 32, is located so as to be operable by hand, while the contact probe 16 is held in the locale of a test point. In the embodiment shown, these switches 32, 40 can provide a stimulus to selector means from a point re¬ mote from the meter itself to cause the meter to oper¬ ate in a desired test and/or report format. The selec¬ tor means, which preferably comprises a microprocessor programmed to direct meter operation in response to re¬ mote stimuli and switch means on the meter will be described in detail below. While the device is shown as providing remote stimu¬ lus by means of electrical contact switches on the probe, other remote stimuli can be employed, including: proximity switches; electromegnetic stimuli such as radio waves, heat, light, (visible, ultraviolet, and infrared) can actuate switching devices responsive to them; sonic stimuli such as voice, clickers, whistles, or other stimuli (audible and inaudible) can actuate switching devices responsive thereto; and other sources of remote stimuli capable of transmitting a switching signal, e.g., remote telephones can provide stimuli and receive reports. Switch 32 is shown here as a button-type, normally- open contact switch having contacts 34 and 36 electri¬ cally connected to leads 38 and 39 which enable connec¬ tion to the meter. Switch 40 is shown also as a nor¬ mally-open contact switch, including contacts electri¬ cally connected to leads 46 and 48 which enable connec¬ tion to the meter. Preferably, of these switches, 32 is coupled to the selector means to control test format and the other, e.g. 40, is similarly coupled to control report format. In the preferred embodiment, the switches will be operable without setting the probe down. For example, switch 32 can be located for ease of operation by the index finger and switch 40 for operation by the thumb. Control of test and/or report format by the opera¬ tor at the point of test, remote from the location of the meter, is extremely advantageous. The term "test format" is defined to mean a testing routine which requires a combination of variables including identifi¬ cation of the parameter to be tested, the scale to be used, and any other function defining a test procedure which is required by the meter circuitry to accurately measure and report test results. The term "report format" is defined as a routine for reporting a com¬ bination of variables including identification of the parameter being tested, the scale range, any warnings or special procedures to be followed, the frequency of reporting, the number of significant figures reported and the sequence of reporting these and other variables which are significant to yield a clear and concise re¬ port with sufficient detail under the circumstances. As will be described later, means, typically ROM chips, are provided to store a plurality of different report formats which can be accessed by the selector means in response to remote stimulus or on-meter switch¬ ing means. Upon command from the selector means, the desired test and/or report formats are directed to a microprocessor to cause the meter to function in the desired test and/or report format. As will be des¬ cribed later, reporting can be by a visual display, or by an audible signal such as synthesized speech via speaker 15 shown in Figure 4, or a combination of these. However, the visual display, such as LCD shown as 13 in Figure 1, will most typically be controlled to operate in a standard format, which, for example, indi¬ cates the parameter being measured, the range scale, whether AC or DC current is involved, and the full complement of digits capable of display. Referring now to Figures 2 and 3, a preferred com¬ bination of female and male connectors for utilization with contact probe 16 shown in Figure 5 is shown. Male connector 100 has male member 122 for electrically con¬ necting the probe 20 to the meter via mating with the female connector 200 at plug receptacle 222. Male mem¬ bers 128 and 130 are preferably sized as conventional thermocouple male connectors and electrically connect the thermocouple 26 to slots 228 and 230 on female connector 200. Similarly, male members 238 and 239 electrically connect the test format selector switch to the meter. And, male members 146 and 148 mate with female members 246 and 248 to electrically connect the report format selector switch to the meter. Sleeve 150 has key 152 to assure proper alignment of the male plug 100 into female receptacle 200 by mating with hole 250 having keyway 252. Receptacle 254 can receive a stan¬ dard male probe plug for high amperage tests. It is an advantage of the particular female connec¬ tor 200 shown that it can be employed with specialized male connector 100 or can receive a conventional thermo¬ couple male connector if this is desired, say where a specialized thermocouple is required, and it can also receive a standard test probe male connector where this is desired. By operating the remote test mode selector switch, the selector means is stepped through a predetermined sequence of test formats; for example, first AC or DC, then ohms, then amps, then voltage and then tempera¬ ture. Where, as in the preferred embodiment of the invention, the meter is of the autoranging type, there will be no need to select range of scale manually. How¬ ever, the microprocessor of the selector means can be programmed to step through various scale ranges by, say giving two switching pulses in rapid succession. Manual on-meter electronic test format selector switches are also provided for any of the same test for¬ mats controlled by selector switch 32 as well as for different test formats, as is desired. The test format switch panel 300 on the meter in Figure 1 is preferably a membrane panel enabling electronic switching without more complex and costly mechanical switches. Panel 300 shows eight test formats on switch pressure points. These enable testing for amperage on the 20 milliamp (20 ma) , and 200 milliamp (200 ma) and 10 amp (10a) scales, ohms (.Ω ) , voltage (V) , temperature in degrees Celsius ( β C), either AC or DC (£5) , or for circuit con- tinuity ( ► ( ) . it will be possible of course to pro¬ gram for selection of any other desired test formats. It is desirable to display the test format selected on the visual display 13, and also to supply this infor¬ mation for selection as required by various audible reports formats. In addition to the panel 300, button-type switches 302, 304 306 and 308 are provided for various meter control functions. Switch 302 can, for example, be a power switch; 304 can lock the visual display on any current display; 306 can lock the meter on a particular report format; and 308 can lock the meter on a particu¬ lar report format; and 308 can lock the meter on a par¬ ticular test format. Panel 400 is similar in construction to panel 300 and is shown to provide eight selector switches for selecting the desired report format. As shown, there is a memory switch (M) which causes any sequence of test reports to be stored, to the capacity of the memory, on a first-in-first-out basis, for alter review and recording. The meter will, when in the delta for¬ mat ( Δ ) report any change in test format selected by the operator or directed by the autoranging meter. In the timed report format (T) , a test reading can be re¬ peated, say every five seconds, to test for drift or other change in magnitude; in the single report format (S) , the meter will delay a fixed amount of time, say 1 or 2 seconds, for the test reading to stabilize and then give a single report, without repeating it. Alter¬ natively, in the single report format, the test signal can be tested electronically to assure its stability prior to giving the single report. The remaining switches (1), (2), (3), and (4) on report format selec¬ tion panel 400 enable selecting the number of signifi¬ cant digits for the report. Any of the formats can also provide caution and override messages to the opera¬ tor where damage to the meter or circuit may be possi¬ ble or where an incompatible series of instructions was given as to test format and the microprocessor has caused override of the instructions. It is also desired to include a suitable interface such as a telephone jack and/or a RS 232 port for en¬ abling receiving test and report format instructions and transmitting test results or warnings. For exam¬ ple, a telephone call can be initiated by the meter where an ongoing test with fixed probes senses a pre¬ determined desired or undesired value or condition. The report can be made by speech with the remote opera¬ tors having the ability to give further instructions. Also the test information can be continuously or periodically transmitted to a computer for storage and/or analysis. Reference is now made to Figure 6 which shows a block diagram representing the interrelations of basic circuit components for a preferred form of the inven¬ tion. Centrally located in Figure 6 is a microproces¬ sor 500 which is programmed preferably: to receive signals from test format switching means including re¬ mote 502 and local 504 (on the meter housing) switches generate a test format selection signal, and send the test format selection signal to a meter circuit 510 to cause the meter to operate in the selected format (the meter will preferably include internal test format switching circuitry 506 to select the appropriate ana¬ log input from test probes or other input device on instructions from the microprocessor) ; to receive a meter output signal indicative of a measured value of a parameter and generate a report signal according to a selected report format; to receive signals from report format switching means, both remote 508 and local 509, generate a report format selection signal, and send the format selection signal to means 520 which store a plurality of report formats to cause the selected re¬ port format to be directed to the microprocessor; to receive the selected report format and generate a re¬ port signal according to the selected report format; and to generate a signal indicative of the desired report and send that signal to a visual display 530 and/or a speech synthesizer 540 to audibly report the test results as synthesized speech in the selected re¬ port format. A microprocessor, such as an NEC 7503 can be employed. Suitable as the speech synthesizer is a 7759 avail¬ able from NEC. Preferably, replaceable ROM chips, such as an NEC 23C100, will be employed to enable the speech synthesizer to operate in any of a number of desired languages. The speech synthesizer will receive a sig¬ nal indicative of the desired report and transmit it to the speech synthesizer which in combination with an amplifier 542 and speaker 544 will audibly report test results and other desired test information in the selec¬ ted report format and the desired language. The term "speaker" is meant in its generic sense and includes all electroacoustical transducers effective for report¬ ing audible speech and includes such devices and ear¬ phones and the like. If desired, a simple on-off switch can be operated on the meter or-remotely to turn the speaker on and off as desired. The various report formats are burned into means 520 which can comprise ROM chips as above or those on board the processor as above. Figures 7 through 10 show another form for a speak¬ ing test meter 550 in accordance with the invention. Meter 550 has a generally rectangular crossection hous¬ ing 552 formed with a first portion 554 containing a speaker 556 (see Figure 11) behind a slotted segment 558. Another portion 560 includes controls provided in the form of a rotary function selector 562 connected to the pole of a multiple position switch inside housing 552. The function selector 562 enables the generation of unique function signals by which meter 550 can mea¬ sure temperature, millivolts, volts, ohms, milliampers and amperes. For these functions, probes such as 14 and 16 of Figure 1 are inserted into probe connectors 564.1-564.3. Temperature is measured with one or several thermocouple probes that are connected to tem¬ perature receptacles 566.1 and 566.2 at the rear of housing 552. A pivoting handle 553 is provided. Meter 550 has an auto-ranging capability. In the various function settings of function selec¬ tor 562 different operating modes are provided with mode selection switches 570.1 thorough 570.5 located above, a digital, four decimal digit display 572. The mode switches 570 provide, by respective repeated actua¬ tions, an AC or DC mode with switch 570.1; a tempera¬ ture selection with switch 570.4 using a single thermo¬ couple Tl or T2, or the difference T1-T2 between them; a centigrade or Fahrenheit temperature scale selector with switch 570.5; a continual speech pattern, or one that operates on command only or one that operates at selected intervals by switch 570.3 and a display round¬ off selector 570.2 with which one can limit the display to the right of the decimal or radix point. As ex¬ plained below, the displayed digits are the ones that are spoken. Selection of anyone mode with any one switch can be done with repeated actuations that cycle through all the modes controlled by the switch. A speech request signal generating switch 571 is provided to stimulate a speaking of a value at the meter. A commonly available multimeter chip is employed such as the Max 133 made by the Maxim Corporation. In the embodiment of Figures 7-10, the test meter's speaking capability is made particularly suitable for adaptation to different languages. This is done by in¬ corporating, as shown in Figure 11, in addition to a main microprocessor 590, a replaceable speech module 592. The speech module 592 includes a slave micropro¬ cessor 594 and a speech chip 596. The speech chip stores the digital samples of various words that need to be spoken in order to enunciate the meter functions, modes and parameter values through speaker 556. The speech chip is a standard device, such as the NEC 7554 and responds to the control signals from the slave microprocessor 594. The latter in turn operates to translate the meter data to be pronounced into signals that then can cause the speech chip to pronounce the meter data in the proper way. Hence, processor 594, being a replaceable device with chip 596, can be programmed with the rules of the specific language to be spoken while the test meter with its main processor 590 can remain the same. This simplifies the test meter 550 while still accommodating the various language complexities that are encountered. Communication between the main processor 590 and the speech module 592 is obtained along a serial port 598 with the aid of control lines and a busy or ready control line 600. Data is transferred from the main processor 590 in a fixed serial train of bit pulses whenever the meter 550 requires a spoken format. The operation of main processor 590 is generally set forth in the steps illustrated in Figure 12. Vari¬ ous automatic operations are performed, some of which are well-known. Thus, at 602 various flags, registers and memory locations are reset or set to initial values. At 604 various selected meter functions and modes are stored and the occurrence of a new selection by the operator is noted by setting an appropriate flag. The display settings are identified at 606 along with a suitable round-off number that corresponds to how many digits are to be displayed. Ordinarily, test meter 550 can display parameter values in four digits. For example, in a lower scale, one digit can be on the left of the decimal point and three on the right. In measuring and speaking of a parameter, however, the operator may only be interested in two of the digits, namely, the one to the left and the one to the right of the decimal point and hearing the meter speak all four digits can be both bothersome and unnecessary. In the meter of this invention, therefore, the operator can select a display of desired digits by producing a round-off signal with mode switch 170.2. Actuation of this switch successively, cycles the display through a showing of one, two, or three digits to the right of the decimal point, depending upon the scale. The main microprocessor 590 identifies this round-off number at step 606. At 608 the parameter of interest is measured and its value stored and displayed. A test is then made at 610 whether a spoken format of the parameter measure¬ ment is required only upon command as selected with mode switch 570.3, such command is generated when the probe switch 32 or switch 571 is actuated, see Figures 5 and 11. If so, the presence for such command is tested for at 612. In the absence of a command, a return is made to step 604. If a command is present or if a speech request arises because the regular interval between such re¬ quests, as selected by mode switch 570.3, has termi¬ nated as tested at 614, then a speech routine is en¬ tered at 616. Meter data is transferred at 618 to the speech module 592 and a return is made to step 604. The slave microprocessor 594 of Figure 11 is pro¬ grammed with a read only memory to respond when re¬ quests are made for a speech command. The processor 594 operates as illustrated in Figure 13, starting at step 620 with various program start up routines includ¬ ing resets, flag setting, etc. At 622 a test is made whether a request for speaking has been received from the main processor 590. If not, the slave processor continues in this waiting mode. If so, however, data from the main processor 590 including the most recent measurements are transferred at 624 into slave proces¬ sor memory 626. The data transferred consists of the information as set forth at 630 in Figure 15 and is transferred in serial format into memory 626 in Figure 11. In response the slave microprocessor 594 sends a busy signal on line 600 (see Figure 11) and commences at 640 in Figure 13 with a resetting and initializing of the speech chip 596. At 642 the new function flag received from proces¬ sor 596 is checked for whether the operator had selec¬ ted a new function or a new mode. If so, the current function is identified at 646 and the speech chip in¬ structed to audibly speak the function at 648. At 650, the current mode is identified and its spoken format occurs at 652. A return is then made at 654 to await the next speech request at 622. In this manner, an operator can cause a change in function or mode without also causing a probably mean¬ ingless speaking of a measurement since the probes probably have not yet been applied to appropriate test points. In the event no new function or mode was selected as determined at 642, the processor 594 proceeds to instruct the speech chip 596 to speak the current mode at 660 and at 662 the value of the measurement in accor¬ dance with the round-off in effect for the display is identified and this value is spoken at 664. A return is then made to await a speak request at 622. The speech chip 596 is provided with digital words representative of digitized samples of analog speech of the words needed to compose all of the test meters func¬ tions, modes and measurements. The speech produced by the chip then includes combinations of the words in the sequence as called out by processor 594. The words are recomposed into an analog form by a d/a converter whose output is applied to an amplifier 670 (see Figure 11) coupled to drive speaker 556. Figure 16 shows at 672 the words stored in speech chip 596. These include the whole integers from zero through twenty, the decades through ninety, and those others as shown. The rules of speech then cause these words to be combined to say for example "two hundred fifty six point three ohms" for a measurement of 256.3 ohms. Figure 14 illustrates slave processor 594 steps with greater detail. After test 642 determines that for an existing function and mode, a new measurement is to be spoken, a test is made at 674 whether an over- range condition occurred. This test involves examining the overrange flag shown in Figure 15 and corresponds to either an excessively high or low measurement by the main processor 590. If so, the next test at 676 is whether resistance is being measured so that a subse¬ quent test at 678 can determine whether this is a short circuit or open circuit condition. The corresponding words are spoken at 680 or 682, and 684 before a return is made to step 622 in Figure 13. If no resistance is being measured "overrange" is spoken at 686 and a return is made to 622 in Figure 13. If no overrange condition exists then, after speaking the temperature mode at 690 after test 692, a test is made at 694 for negative measurements by checking the sign flag in Figure 15. If negative, that word is spoken at 696. At 698, the proper radix routine is selected so that at 700 the number actually shown in the display can be spoken. The units represented by the number are then spoken at 702 and a return is made to step 622 in Figure 13. Figure 17 illustrates the portion of Figure 13 in greater detail for the case where a new function is selected. Detailed illustrative steps are shown for the case where temperature is the new function, fol¬ lowed by another speaking request to illustrate the speaking routine for a particular temperature measure¬ ment. At 712 a test made whether the new function, as identified by the new function flag, is temperature. If not, a test is made at 714 whether the new function is millivolts. This continues at tests 716, 718 and 720 for the functions as noted, until by process of elimination the new function must be amperes. This is spoken at 722 and after DC or AC modes are identified at 724 the modes are spoken at 726 or 728. Note that the other functions are handled in a similar manner. When temperature is the new function or new mode, a routine at 740 is entered to first speak the tempera¬ ture mode. Thus at 742 a test is made whether a thermo¬ couple at the Tl port is used. If not, then the "T2" mode is spoken at 744. However, if this thermocouple is used, then after Tl is spoken at 746 and a test at 748 confirms that the difference mode T1-T2 is used, the word "minus" is spoken at 750 followed by "T2" at 744. At 752 a test is made whether temperature is being measured in centigrade or Fahrenheit and the appropri¬ ate mode is pronounced at 754 or 756. If after a new temperature function or mode has resulted in an announcement, then following the steps as shown, tests are made at 760, 762 and 764 to deter¬ mine the radix being employed in the display. In each case where that display radix is identified, an appro¬ priate number is spoken according to the routines 766, 768, 770 and 772, followed by the speaking of the units for that measurement at 774, in this case °C or β F. Figures 18 through 21 illustrate the number speak¬ ing routines employed with different radices. In case of a radix of four (see Figure 18) a number in the thousand can be spoken at 780, unless it is zero. Then the hundreds digit is spoken at 782 unless it is zero, and a tens digit at 784 if that is not zero until at 786, a ones digit is spoken. Note the exception for a teens number which is spoken at 788 if needed while subsequently skipping the tens and ones digits. The number speaking routine thus follows the rules that are peculiarly applicable to the English language. If another language is used, a different number speak¬ ing routine probably would be needed. In the Figures 19-21 a test is also made whether numbers occur after the radix decimal point since the meter does provide four digit measurements. Thus at 794 a test is made whether there are digits after the radix point as shown in the main processor data in Figure 15. If there is such digit, the decimal "point" is spoken at 796 followed at 798 by the first digit after the decimal point. In Figure 20 for a radix of two there can be two digits after the decimal point, but the second digit is not spoken if it is zero as determined at 800. In Figure 21 all digits present in the display to the right of the decimal point are spoken at 802. The above description is for the purpose of teach¬ ing the person or ordinary skill in the art how to practice the present invention, and it is not intended to detail all those obvious modifications and varia¬ tions of it which will become apparent to the skilled worker upon reading the description. It is intended, however, that all such obvious modifications and varia¬ tions be included within the scope of the present invention which is defined by the following claims.

Claims: 1. A test meter having a plurality of selectable test and/or report formats comprising: selector means, operable responsive to a remote stimulus, for causing the meter to operate in a desired test and/or report format; means for contacting a test point and communicating a test signal to said meter, said signal being indica¬ tive of a value of a parameter at said test point; and means responsive to said signal for reporting said value. 2. A test meter according to Claim 1 wherein said selector means includes a switching device responsive to electromagnetic stimulus. 3. A test meter according to Claim 1 wherein said selector means includes a switching device responsive to sonic stimulus. 4. A test meter according to Claim 1 wherein said selector means is responsive to an electrical stimulus from a remote contact or proximity switch. 5. A test meter according to Claim 4 wherein said means for contacting a test point comprises a contact probe configured for being held and positioned at a desired test point by hand and said switch is operable by hand while said probe is held in contact with a desired test point. 6. A test meter according to Claim 5 including a second switch means located on said probe and operable by hand, one switch being coupled to said selector means to control test format and the other being coupled to said selector means to control report format. 7. A test meter according to Claim 6, wherein said probe further includes a thermocouple for sensing tem¬ perature, the thermocouple leads extending to a male connector common with leads for other component of the probes, and said meter includes on a housing a female connector which is configured to receive either said male connector or standard thermocouple and/or standard probe connectors. 8. A test meter according to Claim 1 which further includes means for audible reporting test information. 9. A test meter according to Claim 8 wherein said selector means enables control of said means for audibly reporting. 10. A test meter according to Claim 8 wherein said means for audibly reporting test information comprises a speech synthesizer, a microprocessor programmed to function with the speech synthesizer, and an amplifier and speaker to report test information as speech. 11. A test meter according to Claim 10 wherein said means for audibly reporting test information further comprises means for storing a plurality of selectable report formats. 12. A test meter capable of reporting test results as speech in any one of a plurality of selectable report formats, comprising: means for receiving a test signal, generating a meter output indicative of a measured value of a para¬ meter, and directing said meter output to a microproces¬ sor; means for storing a plurality of selectable report formats and directing a selected one to said microprocessor; selector means for causing a particular report format to be directed to said microprocessor; a speech synthesizer; and a microprocessor programmed to receive said meter output and cause the speech synthesizer to audible report test results in a selected format. 13. A test meter according to Claim 12 wherein said selector means is operable responsive to a remote stimulus. 14. A test meter according to Claim 13 wherein said means for receiving test signals comprises a contact probe configures for being held and positioned by hand and includes an electrical switch which is operable by hand while said probe is held in contact with a desired test point. 15. A test meter according to Claim 14 including a second switch means located on said probe and operable by hand, one switch being dedicated to control test format and the other being dedicated to control report format. 16. A test meter according to Claim 15 wherein said probe further includes a means for sensing temperature having leads extending to a male connector common with leads for other components of the probe, and said meter includes on a housing a female connector which is con¬ figured to receive either said male connector or a stan¬ dard thermocouple connector and/or a standard probe connector. 17. An electronic multimeter having a plurality of selectable test and report formats comprising: selector means including a microprocessor, oper¬ able responsive to a remote stimulus as well as switch¬ ing means on the meter, for causing the meter to oper¬ ate in desired test and report formats; probe means for receiving a test signal; an autoranging multimeter circuit capable of generating a meter output responsive to said test signal and indicative of a measured value of a para¬ meter, and directing said meter output to a micropro¬ cessor; means for storing a plurality of selectable report formats and directing a selected one to said micropro¬ cessor; selector means for causing a particular report format to be directed to said microprocessor; a speech synthesizer; and a microprocessor programmed to receive said meter output and cause the speech synthesizer to audibly report test results in a selected format. 18. A multimeter according to Claim 17 wherein said probe means comprises a contact probe configured for being held and positioned in the locale of a desired test point by hand and includes an electrical switch operable by hand while said probe is held in contact with a desired test point. 19. A multimeter according to Claim 18 including a second switch means located on said probe and operable by hand, one switch being coupled to said selector means to control test format and th other being coupled to said selector means to control report format. 20. A test meter according to Claim 19 wherein means are further provided for storing a the of test format messages and directing a selected one to said microprocessor; and said microprocessor is programmed to cause the speech synthesizer to audibly report a test format message in response to selection of a given test format. 21. A test meter for measuring and displaying a selected one of a plurality of different parameters and having speech generating means to produce audible speech of the selected parameter, comprising: microprocessor means for generating a plurality of meter data signals related to the current operation of the meter and the measured value of the selected para¬ meter; a speech module operatively connected to the main microprocessor, said speech module including: speech chip means for storing words to be audibly reproduced in a desired language and representative of various mea¬ surements, functions and modes related to parameters that can be measured and displayed by the meter and second microprocessor means effectively coupled between the main processor means and the speech chip means for delivering, as determined by said plurality of meter data signals from the main microprocessor means, a plurality of command signals to the speech chip means to cause the latter to generate audible reproductions of selected ones of said plurality of signals in con¬ formance with rules applicable to the desired language. 22. A test meter according to Claim 21 wherein the speech module is a replaceable unit. 23. A test meter according to Claim 21 wherein the second microprocessor means includes: means responsive to a speech request signal from the main microprocessor for initiating the delivery of said plurality of command signals to the speech chip means. 24. The test meter according to Claim 23 and further including: means in said main microprocessor means for deli¬ vering, effectively in response to a speech request signal said plurality of meter data signals to the second microprocessor means. 25. The test meter according to Claim 24 and further including: means in said second microprocessor for storing speech rule signals for determining a sequence of com¬ mand signals needed to produce said audible reproduc¬ tions compatible with the desired language. 26. A test meter according to Claim 25 and further including: a contact probe configured for being held and positioned at a desired test point by hand, and switch means on said probe to produce a said speech request signal. 27. A test meter according to claim 24 and further including: means for selecting a desired display resolution of parameter measurements and produce a round-off signal indicative thereof; and means responsive to the round-off signal for controlling the selection of the command signals to establish an audible pronunciation of the displayed parameter measurement. 28. A test meter according to Claim 27 and further including: means for rounding-off displayed parameter mea¬ surements to a desired place on the right side of the decimal point and generating said round-off signal indicative thereof. 29. A test meter according to Claim 28 wherein said plurality of meter data signals that are delivered to the second microprocessor includes said round-off signal. 30. A test meter according to claim 29 and further including: means for generating a first temperature signal representative of a measurement with a first temperature probe; means for generating a second temperature signal representative of a measurement with a second tem¬ perature probe; and means for generating a signal representative of the difference between the first and second temperature signals.

Inventors: CRIMMINS JAMES PATRICK, HOLLANDER MILTON BERNARD, MCKINLEY WILLIAM EARL, STORER IAN K, CRIMMINS, JAMES, PATRICK, HOLLANDER, MILTON, BERNARD, MCKINLEY, WILLIAM, EARL, STORER, IAN, K.
Applicants: OMEGA ENGINEERING, OMEGA ENGINEERING, INC.
Application year: 1988
Main classification: G01L1
IPC codes: G01D21, G01R31