DE3238487A1 - Method for displaying physical measurement quantities on an analogue scale and electrical circuit arrangement for carrying out the method - Google Patents

Abstract

To be able to combine the advantages of an analogue display with the advantages of a digital display in an electrical measuring and control unit, a method for displaying physical measurement quantities which can be converted into electrical quantities or are electrical quantities themselves on an analogue scale is proposed in which the measurement quantities are displayed directly as digital electrical quantities or indirectly after conversion of analogue into digital electrical quantities on a liquid crystal display (LCD) constructed as a scale and the upper and lower scale limit value is set in such a manner that the setpoint of the measurement quantity to be displayed appears at a predeterminable point on the scale, particularly at the centre of the scale. <IMAGE>

Description

V / experienced for the representation of physical measurands on an analog scale and electrical circuitry for carrying out the process

The invention relates to a method for representing physical measured variables, which are converted into electrical variables are changeable or are themselves electrical quantities, on an analog scale.

A large number of measuring devices for the various parameters are known. You can get these devices in two Divide groups.

The first group includes mechanical measuring and control devices, while the second group includes electronic Includes measuring and control devices.

In the first group of mechanical measuring and control devices a moving coil measuring mechanism is generally used or Depending on the parameter to be measured, also other mechanical drive elements. On this be not discussed here.

These drive elements act directly on an indicator which shows on a predetermined scale which measured value is just reached. With two mechanical actuators, an upper and a lower

Limit value can be set. When one of these limit values is reached, a contact is mechanically closed or opened for a switching process can be triggered.

The group of electronic measuring devices is somewhat larger. Basically with all devices In general, the electronic recording of the data is the same, as is its evaluation. The setting of the limit values is done either via keyboards or via rotary knobs that work at the same time can also serve as a scale, - The above rotary knobs with scales are used as display units or digital displays, as well as displays about Light emitting diodes or light bulbs.

The devices can be built with the required measuring accuracy will. .,

The digital displays described above are electronic Control devices have the very big disadvantage in practice, that the actual actual value is very precise can be read, often over several places

behind the 'comma, but an immediate recognition of the set measurement value, especially above greater distances are not possible at a glance. This is why the mechanical analog display is used Devices are still given preference. With these devices you can also use it over a greater distance The pointer position can be seen at a glance whether the desired target value is being adhered to or not. An example is the cockpit in the aircraft, where a lot of devices at a glance must be recorded. Since these devices are rotated with their scale so that the pointer is in the normal range all point in one direction, the pilot can easily see a large number of devices at a glance to monitor. This would not be possible with digitally displaying devices. It is also essential that with analog displays Devices, a scale always has a certain length. Because this scale starts at zero and at that If the maximum value ends, the resolution of these "scales is sometimes quite imprecise. For clarification purposes, the following section an example:

An injection molding machine is used for heating of the granulate a built-in control device. Since different plastics are injected, so are those Temperatures for the melting point of the granulate are different. Since temperatures up to 500 are recorded the scale of the measuring device must show a range from 0 to 500 ° C. Since the scales usually have a If you mark an arc of 270 mm, the scale shows a temperature of 1.85 C per degree of angle. This means that with a scale diameter of 100 mm per degree Celsius the distance between the two graduation marks 0, * »? mm would be. From this it can be seen that good resolution is limited with such scales. UJ is now predominantly in one company Processed material which has a melting temperature of 200 ° C, the measuring device would have to be in the control unit exchanged in order to obtain an optimal resolution. However, this is true in most cases associated with great costs and circumstances.

Proceeding from this, the invention is based on the object of a method and an electrical circuit arrangement for a display and control device,

through which the advantages of the analog display with the Advantages of the digital display can be combined. Furthermore, it should be achieved that in every desired Sub-range within the entire measuring range, the display can be spread.

To achieve this object, the invention proposes procedural steps according to claims 1 to 5 before. An electrical circuit arrangement for achieving the object of the invention is set out in the claims 6 to 12 designated.

The invention is described in more detail below with the aid of a functional description.

Since the display and control unit (ASE) works on an electronic basis with the aid of a "microprocessor is built in NMQS / CMOS technology, which is described in more detail below, all physical Quantities are measured that result in changes in resistance can be detected, or also those physical measured variables that are represented by a frequency. This includes, for example, the physical quantities pressure, temperature, voltage, current, frequencies, Time etc.

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The above sizes are made with suitable sensors scanned and passed on to the ASE. These sensors are either built into a bridge circuit, or there are tensions impressed over a Power source ale direct supply to the MeB amplifier fed. The MeBverstMrker, for example consists of a CMDS operational amplifier these signals on to an analog-digital converter, which converts these DC voltages into a frequency, which is made available to the processor as a measured variable.

Since the recorded measured values must be clearly presented to the user, a liquid crystal display, called LCD for short. Because the LCD display is difficult to read in the dark there is lighting in the ASE for the display.

With the help of this display it is possible to display the measured values in analog and digital form at the same time. The liquid crystal display conveys the following information:

1. In a three-digit decade ^x, for example, the actual value of the measured variable.

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2. On a scale made up of LCD elements of approximately 1ÜD mm length is again in 1DO individual steps of the actual analog display, and to a second darUberliegenden, also constructed out of the upper and lower limit displayed in 1DO individual steps.

3. two displays, with the help of which · the Analog scale can be made.

U. The specification of the measured value to be recorded.

As can be seen from the description of the display options, it can be seen that with this display the actual value can be read directly digitally, i.e. with the highest accuracy and a good overview is guaranteed. In the case of the analog display, it should be emphasized that the band can be spread. This means that the total scale in the area to be measured can be expanded by a maximum of 10: 1, for example. For example, with a measuring range of D - 999 C, the scale would also show 0 - 999 ^D G with a ratio of 1: 1. With a spread of 10: 1

shows the scale from its beginning to its end only after 1GD ° C. This means with one division van 1DD parts on the total scale per graduation a value of 1 C. On the other hand, it would not be for one spread scale of Uert per graduation 10 C. It can be seen from this that a 10-fold better readability is guaranteed.

Since the setpoint to be measured is somewhere between the

J - the beginning and end of the measuring range, the

Possibility created with a spread of the scale the lower start value and upper end value of the Adjust the scale. The lower and upper limit values are given as a percentage of the total scale » A difference in the range display is advantageous to avoid overlapping and should be between

_ £. the lower and upper limit value minimum 1G % be

wear. As an example for clarification:

'. The total measuring range of the ASE should be 999 ° C. the

The temperature to be measured at the moment is 5OD C. In this case, with the highest resolution, the lower limit value of the analog scale is set to k5% , the upper limit value is automatically set to 55 % because of the 10% difference. Since the analog scale now starts at t * 50 ° C and at 550 ^D C

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ends, you can read 1 C per graduation mark on the scale. This allows, the upper, souiie the lower limit value with a difference of up to 1 ⁰ C to introduce them to the target value.

It is also possible to move the percentage setting of the lower and upper spread on the scale so that that when several measuring devices are lined up with the different measuring points, the scales can be set so that they all have the same section. This will make the Überuacher of the measuring devices given the possibility to detect at a glance whether all devices are normal or indicate some malfunction. Only if the devices are different the supervisor would "step closer and digital." read off the actual actual value. With this Description and with the help of the drawings of the display you can see that the summary digital display and analog display offers decisive advantages. These virtues could only be realized through the high quality components of the electronics.

Show it:

FIGS. 1 to 3 displays with different settings;

FIG. U shows an enlarged illustration of the LCD display;

FIGS. 5 to 7 show different views of an ASE; Fig. 8 is a block diagram of the ASE.

In Figure 1, a display and control unit is shown from the front , uiobei the two superimposed scales formed from LCD elements and the digital display also formed from LCD elements can be seen and also percentages over the respective measuring range or the degree of spread of the scale can be seen . In FIG. 1, the actually set actual values plus 5Q0 C are shown digitally and can also be seen in analog form on the lower scale . The upper scale is spread on a measurement range between k5% and 55%. In addition, .ein. lower limit is set at USO C while the upper limit is set to 51D C.

In FIG. 2, if the Tst value is the same, it is plus 500 C the same digital display and also on

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the lower scale shows the same analog display. The upper scale is unspread and covers the entire measuring range from D to 99 %. With this setting, too, the lower limit value is set at <«90 C and the upper limit value at 510 C , whereby these limit values determine the control cycle. In the comparison of Figures 1 and 2 it can be clearly seen that the display accuracy with a spread according to

^v - Figure 1 is considerably larger, the analog actual value display taking place exactly in the middle area of the scale, the setting of this value on the analog scale naturally being dependent on the setting of the spread of the scela. In the upper scale, the limitation of the measuring range to the upper or lower limit value is shown in black. If - 'the setpoint is either the upper or the lower

Limit value is reached, a corresponding control / Process, so that the actual value is either raised

or is lowered. Various buttons can be seen on the display and control unit with which the individual settings can be made. On the left side there is a key 1, with which the lower range of the spread is set, and a second key Z, with which the lower one

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Limit value is set. On the right side there is a key 3 with which the upper range of the spread is set and another key i * _{r is} used to set the upper limit value. In the middle of the keypad there are two further keys 5, 6, whereby the limit values to be set run numerically upwards after pressing the first key 5, while they run numerically downwards after pressing the second key 6. Furthermore, there is a key 8 in the middle, which spreads the scale after pressing (magnifying glass) and a second key 7, which takes back the spreading of the scale after pressing. To set the respective values, the associated area key is pressed with one finger, and the key for counting up or down is pressed with the other finger. When the limit values are set, the actual display goes out automatically and the set value appears. After releasing the setting buttons, the actual display appears again automatically. This arrangement of the buttons prevents incorrect operation to a large extent.

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FIG. 3 shows a variant in which the measuring range is set between 20 % and 30 % of the total measuring range from 0 to 999 ° C. Furthermore, the upper limit is set to 260 ⁰ C and the lower limit to 2 ** QC. On this table it is made clear that even with an actual value to be measured. Setpoint of plus 250 C the display of the lower analogue scale must be aligned exactly in the middle. The analog indicator on the lower scale can therefore be moved to any point on the scale for any measurement point. This means that all scales of devices arranged next to one another can be aligned in the same way.

In Figure 4, the LCD display is shown on an enlarged scale. Each scale 9 or 10 mostly • 100 LCD panels. The upper scale 9 takes on the display function for the minimum and maximum display, while the lower scale 10 shows the actual UJert represents analog. At 11 and 12 iBt, the lower percentage is shown on the digital LCD display and upper measuring range percentage indicated. In the middle of the display is a four-digit LCD display 13, which will be completed in three decades and one

Vorzelchenstelle digitally displays the measured actual level. As BU8 of the previous description shows, there are a number of ways to display and control measured values. But there is a control device is used to control a certain process, and should give the supervisor the opportunity to to carry out surveillance as quickly and easily as possible, .there are advantages and disadvantages with the individual Systems. The ASE according to the invention combines the advantages of the previously known systems in one Device, to which a comparative statement is made below.

The clarity of analog display devices is very good, but under certain circumstances it is the resolution of the scale is quite imprecise. In the case of the digital display devices, the accuracy is very high high, but clarity is no longer guaranteed. A quick optical acquisition of the data can not. With the ABE according to the invention * the analog display was combined with a digital display. This ensures that a good Clarity of the measured value, as well as an exact readability of the measured value is given. Particularly

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What should be emphasized in the case of the analog scale is the fact that that this scale can be expanded if the resolution is insufficient, as described above. This will be done electronic means made possible. There are also the upper and lower limit values with the expanded analogue scale for the control function can be set, it is also guaranteed that the limit values with this increased resolution can be set. Ultimately, these limit values are displayed and set digitally. Furthermore, the EARDMs that are common today give the option of using the To save data securely and to keep them without backup batteries even in the event of a power failure. The digital Measuring devices have the advantage, because they work electronically, that the limit values for the regulation are very high can be set precisely. This applies to the known, purely digitally indicating measuring devices to, as well as for the ASE according to the invention. "With the mechanically operating analog measuring and control devices this is not the case. It is also advantageous in the case of the display and control unit according to the invention all physical quantities that result in changes in resistance or in frequency changes

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can be controlled with one and the same device. In addition, different scales do not have to be built in for different measuring ranges, since the different measuring ranges can be set within a very large range. This has inevitably must for manufacturers of SchaItschränken the advantage that it constituted not different devices, store and install, but tries to procure a GerMtetyp, stock and must assemble _t suitable for the different MeBaufgafaen.

Ulis shown in Figures 5 to 7, the display and control unit consists of three pluggable units 1i », 15,16. These three units can be plugged one behind the other, for example via pin plugs, as can be seen in particular from FIG. In the first visible to the front unit 1, k is the complete display part uiird inserted into the next central unit 15, which 1t to this display part ", is the .Mikroprozessor with analysis, storage, and control electronics, while the third in and last unit 16 is the power section with the switching

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outputs and the power supply is located. The three units 14, 15, 16 are for example from behind with zuiei screws 17 against each other screwed. The mains connections 1fl and the connections are located on the rear wall of the power unit 19 for the sensor and the control outputs 20.

The entire fully assembled unit is supplied by built into a front panel at the front and from the rear / fastened with conventional brackets. The three housing parts are injection-molded from plastic, whereby very dimensionally stable material of relatively high mechanical strength is used. The three housing parts 1 ^, 15,16 are designed in such a way that they form a completely closed housing after being plugged together are connected. Only the terminal strips for the connections on the back of the housing are accessible from the outside. A three-pole terminal strip is provided as the mains connection 18, which

has the connections phase, MP and ground connection. __

The control outputs 20 have a six-pole terminal strip with two three connections for the control function. There is one relay in each device

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with potential-free changeover contacts and a load capacity of 5 amps, which are connected to these terminal strips led bind. The third terminal strip of SenaoranschlusBes 19 is four-pole, so "that on her the various sensors are connected or the voltages or frequencies to be measured directly be created. In the front part of the housing 1 * »is towards the front on the part facing the user, the display with the digital actual value display and the analog display, on which the upper and lower limit values as well as the actual value are displayed Is arranged. RMumllch is below the display a transparent cap 21 attached, which can be opened 1st. Under the transparent cap 21 there are a total of eight buttons, the functions of which are described above been 1st. The eight buttons are assigned once to the upper and once to the lower limit value, once assigned to the upper area, one assigned to the lower area of the display spread and a button for switching the spread of the scale and one key for normal display of the scale and two keys for counting up or down the display during the setting process. When closed

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Transparent cap 21 forms the front panel a smooth one Area that prevents the buttons from being pressed unintentionally.

In Figure B, the circuit arrangement according to the invention is shown in principle in the form of a block diagram. Since the display and control unit works on an electronic basis, the physical quantities detected must first of all be converted into a frequency so that the microprocessor 22 can process this data. For this purpose, the measured values recorded by a measuring sensor 23 are fed to a CMDBr chopper amplifier 2.U , which has the task of a measuring amplifier. The measuring amplifier forwards the data to a UCO element, which in principle represents an analog-to-digital converter 25, which converts the voltages into frequencies which the microprocessor 22 can count. The frequency adjustment must take place with a tolerance of approx. 1 56 », since a three-decade digital display is used. The measurement accuracy in connection with the sensors is around 1 %.

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If frequency signals or voltages are measured directly, they can, as shown at 26, directly fed into the microprocessor 22.

The measurement signal prepared in this way is evaluated by a single-chip microprocessor 22 (NMDS / CMOS). The input signals of the microprocessor 22 are in detail as follows:

1. the analog meter converted into digital pulses the physical quantity to be measured,

2. The limit values that are set using the keypad and made visible in the display.

3. The percentage values that serve as the measuring range setting for the analog scale.

U. the key signals for switching between normal or spread display scale.

The output signals of the microprocessor 22 are:

1. two relay controls for the limit switch relay 27,

2. the control system for the LCD display 29.

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Since all specified function quantities are to be stored in a non-volatile manner, they are used as Memory chip an EAROM 3D is used. This is able to save the stored data even in the event of a power failure, even without backup batteries to be stored until they are consciously changed by the user. The number of doing it too saving sizes is:

Zuiei limit values of three decades each.

Two greetings for the expansion of the analog scale with three-decade display.

Two greetings for setting the measuring range, each with a three-decade digital display.

In the event of a power failure, the two limit value relays 27, 2 [beta] drop out. They take however immediately after switching on the pre-supply voltage again get the position given by the microprocessor.

It should be noted that in the block diagram for the operation and storage of the data in the Microprocessor 22 a key matrix 31 is shown.

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Finally it should be noted that the inventive The solution is essentially made possible by the fact that there is a microprocessor in the display and control unit used - "that has come to solve the complex The task is programmed accordingly. In this way the inexpensive production of such a high quality measuring device has become possible.

All new, in the description and / or drawing disclosed single ^ and combination features are as considered essential to the invention.

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Claims (1)

Patent claims: ( lJ method for the representation of physical measured quantities, which can be converted into electrical quantities or are themselves electrical quantities, on an analog scale, characterized in that the measured quantities directly as digital electrical quantities or formed liquid crystal display (LCD) are displayed, and that the upper and lower scale limit values are set so that the target value to be displayed of the measured variable appears at a predeterminable point on the scale, in particular in the center of the scale. Postal checking account: Dortmund 25334-460 Bank account: Commerzbank A.G. Lüdenscheid (BLZ 45840026) No. 6234512 2. The method according to claim 1, characterized in that the scale formed by the liquid crystal display spread and then the lower and upper dials set. 3. V / experience according to one of claims 1 or 2, characterized characterized in that when several measuring devices are lined up, the scale points indicating the nominal value all aligned and adjusted in the same position with respect to the scale. U. The method according to any one of claims 1 to 3, characterized in that the actual air is also displayed digitally. 5. The method according to any one of claims 1 to U, characterized in that if the actual value deviates from the desired value by an adjustable amount, a control process is initiated by means of which the actual value is brought up to the standard value. 6. Electronic circuit arrangement for performing the method according to one of claims 1 to 5, characterized by the arrangement of a microprocessor (MKP) (22), a data input unit (23, 2U, 25 ", 31) and an analog data display unit (29), wherein the data input unit converts physical measured quantities into electrical quantities and converts the latter into digital pulses which are fed into the MKP (22), and the data display unit (29) also has at least one liquid crystal display in the form of a scale, from which the data transmitted by the MKP (22) is analog can be displayed. 7. Electronic circuit arrangement according to claim G, characterized in that sensors (23) are provided which detect the measured variables and feed them into the MKP (22), with the sensors (23) either in a bridge circuit are built in or are used for the direct transmission of voltages, furthermore between sensor (23) and MKP (22) a measuring amplifier (2 * »), for example a CMOS operational amplifier, and an analog-to-digital converter (25) is connected, the received DC voltage reduced converts it into frequency values that can be read into the MKP (22). β. Electronic circuit arrangement according to Claim 6 or 7, characterized in that of the MKP (22) built in NMOS / CMOS technology is. 9. Electronic circuit arrangement according to claims 6 to β, characterized in that that the MKP (22) is connected via a control logic with an LCD display, which next to several parallel LCD scales a digital actual LJert display includes. 10. Electronic circuit arrangement according to the Claims 6 to 9, characterized in that for manual feeding, in particular of limit values in the MKP (22) a key matrix (31) is provided and with the MKP (22) ally is. 11. Electronic circuit arrangement according to claims 6 to 10, characterized in that that the MKP (22) has two limit relays (27,28) controls, which act as regulating organs in the switching circuit of the monitored device are switched on. 12. Electronic circuit arrangement according to the Claims 6 ble 11, characterized in that an EAROM connected to the MKP (22) as a memory module (3D) for the data read into the MKP (22) is.