FI63113C - ANORDINATION FOR THE INDICATION OF A TV ELLER FLERA I SYNNERHET MEDELST EN BANDVISNINGSANORDNING VISADE VISNINGSSTORHETENS OLIKASTORLEK - Google Patents

Description

631 1 3 Arrangements for indicating the difference between two or more display sizes, in particular those displayed on a line display device

The invention relates to an arrangement for detecting the difference between two or more display quantities, in particular those displayed by a line display device, by means of an intermittently detectable frequency.

5 Process monitoring usually involves a comparison of large measured values describing the state of the process and the desired setpoints. For this purpose, the values can be displayed on a control table or in a control room with display devices suitable for the operator, so that the status of the process can be controlled with a quick glance at the display indications. Several solutions are known to facilitate the visual comparison of the setting-10 value and the measured value by means of illustrative display devices. One such is disclosed in the applicant's earlier Finnish patent application No. 784059, according to which a method can be used to display two quantities, namely the measured value and the setpoint of the control circuit, in clearly distinguishable displays on the same scale of the line display device using different line intensity levels.

This type of display allows for fast and accurate visual comparison of quantities in systems with few control circuits 20 and thus few controllable quantities. As the number of control circuits to be monitored increases, it may be difficult for the operator in certain situations to pay attention to the control circuits among several displays in which the difference between the measured value and the setpoint has increased to an abnormally large absolute value. To draw the operator's attention to the abnormal values, the visual perceptibility of readings deviating from abnormal values can be emphasized by flashing the displays corresponding to the quantities when the absolute value of the deviation exceeds a certain limit. Conventional circuit solutions for the difference detectors required to perform such an operation are based on generating the absolute value of the difference signal and comparing it to the allowable threshold using op amp, rectifier diodes and a separate reference voltage circuit.

British Patent 1,501,503 discloses a way in which an illuminating line to be formed by a similar gas discharge tube can be formed of e.g. When the auxiliary control circuit is connected to the anode voltage control circuit through a switch whose operation is connected to a two-position measurable large selector switch, the position of the selector switch can be identified on the display.

British Patent 1,535,176 discloses a method for indicating an alarm condition on a light strip display implemented with a similar gas discharge tube. The alarm status is indicated by flashing the display periodically so that the quantity to be displayed is displayed alternately, then the whole line is illuminated and then the whole line is switched off.

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British Patent Application 2,019,070 A discloses a light display device formed of light emitting diode (LED) elements, in which the value of a displayed quantity is displayed by illuminating one LED in a row of elements. The same display device also displays one or two settable alarm limits by illuminating the LED corresponding to each alarm limit value. Illuminations are performed periodically and the illumination period of the displayed quantity is longer than the alarm limits, whereby the LED indicating the value of the displayed quantity appears brighter. The alarm limits are set with potentiometers and the alarm limit is exceeded with a comparator. The display flashes if the alarm limits are exceeded.

The object of the invention is to provide a new and e.g. a different size detector solution better suited for applications such as the above-mentioned patent application No. 784059.

35 In order to achieve the object of the arrangement according to the invention, it is characteristic that for each display quantity there is a comparator having a signal corresponding to that display quantity 3 6311 3 connected to the second input and a pulse signal of a continuously operating bed generator to the other input. the frequency is formed from the frequency of the embankment signal by the divider, and that the return input of the divider is connected to the reset of the output signals of the timer circuits.

10

Other features of the arrangement according to the invention are set out in claims 2-6.

From the output of the circuit according to the invention, a pulse-like voltage can thus be obtained by suitable selection of the divider of the divider, which can directly control e.g. the display or a part thereof to flash at a suitable frequency, modulate an acoustic signal or be used as an electrical control signal. The use of the solution provided by the invention is particularly advantageous when the components included in the display control circuits or, for example, existing in any case for the A / D conversion of the display variables, can be used as the comparator and / or the bank generator.

The invention will be explained in more detail with reference to an embodiment of a line display according to the applicant's previous Finnish patent application No. 784059 shown in the figures of the accompanying drawings, to which, however, the invention is not intended to be exclusively limited.

Fig. 1 shows a known line display control circuit as a block diagram.

Figure 2 shows the principle solution of a variable size detector according to the invention in a block diagram.

Figure 3 shows a timing diagram of the circuit of Figure 2.

• Figure 4 shows the variation of the display variables as a function of time and the resulting output signal of the circuit according to the invention.

4 631 1 3

Figure 5 shows in detail an implementation example of a divider recovery signal generating circuit.

Fig. 6 shows the voltages 5 present in the circuit according to Fig. 5 as a function of time.

Figure 1 shows a line display control circuit described in detail in patent application No. 784059, by which a phase-controlled gas discharge on the same scale of the line display is obtained by changing the anode current of the pipe on the one hand and the discharge step speed on the other. The large value of M is then indicated by a uniform light column 20 and a brighter light spot 21 obtained by slowing down the stepping speed of the second large value S. The control circuit implementing the display 8.

As the embankment voltage increases, the phase change circuit 4 cyclically controls the cathodes of the discharge tube 5 for stepping the discharge 20 at a frequency determined by the clock oscillator 2 and the frequency divider included in the phase resistance circuit 3.

As long as the voltage signal of the comparator 8 to the large M is larger than the bank signal, the output of the gate circuit (or) 9 has a state of 1 and the transistor 10 receives constant voltage control and the anode current of the discharge tube 5 gets a certain value due to the control voltage received. When the embankment voltage exceeds the signal voltage S, the output state of the comparator 8 becomes negative, whereby the permanent control coming to the transistor 10 through the gate 9 ends so that the length of the discharge transport portion representing the uniform light column 20 corresponds to the signal M.

When the embankment voltage reaches the second signal voltage S, the level comparator 7 changes its output state to negative, whereby the counter in the extended phase number determining circuit 14 having a preset number of extended phases receives pulses from the phase duration circuit 3 and simultaneously 5 631 1 3 order extending their duration. At the same time, the growth of the output signal of the pen generator 1 is slowed down by the stop circuit 15 of the bed generator. As a result, the durations of the control pulses of the discharge tube 5 are lengthened, and the display line 21 is provided with a more readable 21 until the number of extended phases is reached.

If the value of S is greater than the value of M as in Fig. 1, the discharge is passed over the portion 22 of the display line 10 between displays 20 and 21 dimmed by giving transistor 10 pulsed control from phase resistance circuit 3. Capacitor 12 and resistor 13 connected to transistor base determine how much charge is transferred to anode. per cathode divider.

When both comparators 7 and 8 have changed their initial state and the number of extended phases has been reached, the anode circuit of the discharge tube 5 is cut off via the gate circuit (and) 16 and the glow discharge goes out. The next display period changes to the second scale of the tube thanks to the flip-flop 6. By repeating the sequence of events described above with a sufficiently fast sweep frequency of the embankment generator 1, a flicker-free display according to Fig. 1 is obtained for the discharge tube 5.

According to the invention, a light spot 21 or the entire display representing the setpoint S can be made flashing for the control of the difference size 25 of the display quantities with the new difference detection circuit shown in Fig. 2 when the absolute value | M-S | exceeds a predetermined limit.

The circuit diagram shown in Fig. 2 includes a continuously operating bank generator 1 and a binary divider 30 triggered by rapid voltage changes of the bank voltage peaks connected to its output. A return signal generating circuit comprising comparators 7, , the timing circuits 31,32 connected to the outputs of the comparators 7,8 35 and the gate circuit (nor) 33. The comparable quantities M and S are applied to the positive inputs of the comparators 7,8 and the frequency fo indicating the difference is obtained from the output of the divider 30. In the exemplary case under consideration, the coupling part to the left of the dotted line 631 1 3 6 is available in the control circuit of Fig. 1, whereby the embankment generator 1 and the comparator 7,8 can in any case consist of existing reference numerals in the control circuit of Fig. 1.

5

When the increasing embankment voltage reaches a lower signal at the time indicated by tlr in Fig. 3, the negative voltage step of the change in the output state of the signal M in Fig. 3 starts the timing circuit 31, the output of which produces the negative pulse of Fig. 3b T. Correspondingly, the negative pulse of the same length shown in Fig. 3c is obtained from the output of the timing circuit 32 at time t2 when the pen voltage passes a signal with a higher value, the voltage level of the signal S in Fig. 3. The pulse length T determined by the timing circuits 31, 32 is selected so that the voltage levels M and S of the comparable voltage levels

distance | M — S | being, as in the case of Fig. 3, below the preset limit Δ 1, the time change of the comparators at times t1, t2, the time interval t2-t1 is shorter than the pulse length T. The output of the OR gate 33 then gives a positive pulse in the time interval t2, t1 + T directed to the reset input r, resets the divider 30 for each period of the embankment voltage.

When the difference | M — S | exceeds a predetermined value Δ 1, the first triggered negative pulse ends at time t1 + T before the start time t2 of the latter 25 when no return pulse is received from the output of the gate circuit 33, and the divider 30 can step in step with the pulses of the blade generator 1. If the absolute value of the difference of the quantities M, S | M — S | remains above the set limit A ^ g for at least one period of the output frequency of the divider 30, at the output of the divider 30 a QN state change of the last stage of the divider 30 indicating the difference is obtained.

Fig. 4 illustrates the generation of the output signal of the circuit by showing the variation of the measured value M and the set value S of the control circuit and the resulting output voltage of the circuit compared to Fig. 3 in a long time interval. In the figure, at time intervals limited by dashed lines, the RESET difference | M — S | is below the set limit Δ, ^, and the gate silicon. i? the pulse given by the rin 33 keeps the divider 30 reset. When the difference exceeds the set limit Δ ^, the output of the circuit is obtained from the frequency of the embankment voltage 7 6311 3 by dividing the derived frequency fo as a signal indicating the difference.

The set limit Δ ^, above which the detection of the difference quantity 5 is obtained, can be influenced by changing the pulse length T of the timing circuits.

To control the light spot 21 or the entire display line indicating the magnitude of the setpoint S to flash at frequency f, the difference | M — S | when the limit is exceeded, two methods can be used: either to prevent the generation of extended discharge tube flow pulses forming the light spot 21 while the divider output voltage is true, when the light spot 21 flashes, or to disconnect the tube anode current accordingly, the entire display line pattern flashes. The division ratio 15 of the divider 30 is chosen so that, starting from the relatively high frequency of the embankment generator 1 required to achieve a flicker-free display, a flashing frequency suitable for the eye, e.g. 1-2 Hz, is obtained.

Figures 5 and 6 show in detail a circuit pre-20 signal for generating a return signal of the divider 30. The timing circuits 31, 32 are implemented as RC circuits in which one terminal of the capacitor C is connected to the output of the respective comparator 7.8 and the other terminal to the positive supply voltage through the resistor R and to the input of the OR gate implemented by the diodes 34. The interconnected cathodes of the diodes 34 are connected to the base of a transistor 35, the inverted voltage of the collector of which controls the return of the divider 30.

At the beginning of the operating period, the diodes 34 and the transistor 35 are conductive and the collector of the transistor 35 enters a voltage level corresponding to the 0 state 30 at the return input of the divider. The negative voltage steps of the state changes of the comparators 7.8 switch the diodes 34 in succession in the blocking direction for the time determined by the time constant τ * RC. If, as shown in Fig. 6, M and S are very close to each other, the latter state change t2 of the comparator occurs before the voltage acting on the ano-35 of the blocking diode has already reached the threshold voltage u determined by the diodes 34 and the transistor 35. . Both diodes 34 and consequent-. t, ... · M k> 'transistor 35 simultaneously enters the inhibit state until the time when the threshold voltage u ^ is exceeded, and a positive voltage pulse corresponding to 1 is obtained from the collector 63113 of transistor 35, which resets the divider 30. If, on the other hand, the difference S and M exceeds the times t1, t2 of the state changes of the comparators 7,8 of the predetermined value Δ 1 differ so much that the cathode voltage of the first diode 34 blocked has time to reach the threshold voltage u 1 before the latter voltage step arrives at the second diode 34 and the transistor 35 between their inhibitions. There is no reset pulse at the return input r of the divider 30, and a frequency fo indicating the difference of the quantities M, S 10 is obtained from the output of the divider 30.

The value of Δ ^. to set, the time constant t can be made to be changed Mo e.g. by using control resistors instead of resistors R.

Only the basic solution of the invention has been described above and it will be clear to a person skilled in the art that it can be modified in a number of different ways within the scope of the inventive idea set out in the appended claims.

Claims (6)

9 63113 Arrangement for detecting differences between two or more display variables, in particular on a line display device, by means of an intermittent detectable frequency, characterized in that for each display variable (M, S) there is a comparator (7,8) with a signal corresponding to that display variable and a second the input signal of the continuously operating embankment generator (1), that the discontinuous detecting frequency (fo) indicating the difference of the display quantities is formed from the frequency of the embankment signal by the divider (30), and that the return input (r) of the divider (30) is connected to the comparators (7, 8) a reset signal generated by the gate path (33) detecting the simultaneous occurrence of the output signals of the timing circuits (31,32) triggered by the state changes, which prevents the output frequency of the divider (30) by resetting the difference of the divider (30) with a predetermined value (Δ ^ g) below. Arrangement according to Claim 1, characterized in that the display is a phase-controlled gas discharge line display tube (5). Arrangement according to Claim 2, characterized in that the continuously operating embankment generator (1) and / or comparators (7, 8) are components existing in the display control circuit (Fig. 1). Arrangement according to one of Claims 1 to 3, characterized in that the timing circuits (31, 32) consist of RC circuits in which one terminal of the capacitor (C) is connected to the output of the comparator (7, 8) and the other terminal of the resistor (R). ) to the constant voltage (+) and the input of the gate circuit (34,35) (Fig. 5). 30 Arrangement according to one of Claims 1 to 4, characterized in that the second display variable (M) is a measured value of the control circuit and the second variable (S) is a setpoint. Arrangement according to one of Claims 1 to 5, characterized in that the display (20-22) or a part (21) thereof is controlled to flash at a frequency (fo) indicating the difference quantity as an absolute value of the difference between the display quantities (M, S). (| M — S |) when exceeding a predetermined value (/ W · 63113