JPH0328343Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention relates to an ultrasonic level meter that can switch between displaying a percentage actual scale value and an absolute empty scale value.

《Prior art》 So-called ultrasonic level meters that measure the contents of tanks, etc. using an ultrasonic reflection method display the distance from the ultrasonic transducer to the contents storage surface (hereinafter referred to as empty scale). It is known that the height from the bottom of the reservoir to the reservoir surface (hereinafter referred to as actual scale) is expressed as a percentage of the actual scale when the tank is full.

《Problem that the invention aims to solve》 In the former case, it is possible to directly read the actual height of the storage surface with a certain degree of accuracy, which can be used to predict overflow, perform maintenance, etc. However, unless you check the distance to the bottom of the storage tank in advance, you cannot know the relative amount of storage compared to when the tank is full just from this instruction.

On the other hand, in the latter case, it is possible to directly read the relative storage amount with respect to when the tank is full, which is convenient for predicting replenishment and grasping the absolute amount, but on the other hand, the actual storage amount It is not possible to directly read how high the surface is, and the accuracy of the indication varies greatly depending on the size of the storage tank.

Furthermore, if both the empty scale and the actual scale are expressed as a percentage, the current relative amount to the whole can be grasped for both the actual scale and the empty scale, but how much margin there will be left is a relative amount. However, in order to determine the actual amount, that is, how many meters it will take to fill up, you must always keep track of the capacity of the storage tank and calculate it based on the percentage of empty capacity.

The purpose of this invention is to provide an ultrasonic level meter that makes use of the characteristics of both level meters described above and can display a percentage actual scale value and an absolute empty scale value by switching between them at will by simply switching the switch. There is a particular thing.

《Means for solving the problem》 In order to achieve the above-mentioned purpose, this invention periodically drives a transducer to repeatedly transmit pulsed ultrasonic waves to the storage surface, and also transmits pulsed ultrasonic waves from the storage surface. An empty scale measuring circuit that receives the reflected wave, converts the time required for transmission and reception into voltage, and outputs this as an empty scale equivalent voltage, and an operator for switching between empty scale and actual scale are set on the empty scale side. When it is set to the actual scale side, the difference between the virtual maximum empty scale equivalent voltage set in advance and the empty scale equivalent voltage at that time is output as the virtual actual scale equivalent voltage. one end is connected to the high-voltage side reference potential point, and the other end is connected directly to the low-voltage side reference potential point or to the actual scale zero point, depending on the state of the empty scale/actual scale switching operator. a series resistor group for generating a reference potential that is selectively connected indirectly to a low-voltage reference potential point via a variable resistor for calibration; and an output voltage of the output selection circuit can be obtained from the series resistor group. A group of comparators that discriminate based on a plurality of reference potentials, and a plurality of light emitting elements driven in accordance with the outputs of each comparator of the group of comparators are sequentially arranged in a row on a display panel, and along the array are arranged a group of comparators for discrimination based on a plurality of reference potentials. A display device having both an absolute distance index and a percentage distance index for displaying the actual scale.

<Operation> According to this invention, it is possible to alternatively display the percentage actual scale value and the absolute empty scale value on a common display simply by switching the empty scale/actual scale switching operator. Therefore, it is possible to directly read the actual height of the storage surface with a certain degree of accuracy, which is convenient for predicting overflow and maintenance, and at the same time, it is possible to directly read the actual height of the storage surface with a certain degree of accuracy. It can also be read directly, making it convenient for predicting replenishment and understanding absolute quantities.

In particular, in this invention, one end of the low voltage side of the series resistance group for generating reference potential is directly connected to the low voltage side reference potential point according to the state of the empty scale/actual scale switching operator.
In addition, since it is indirectly connected to the low voltage reference potential point via the variable resistor for actual scale zero point calibration,
Once you have calibrated the zero point in the actual scale display state, there is no need to calibrate the zero point even if you switch to the empty scale display state, and from now on, you can immediately change the percentage actual scale value and the absolute empty scale value by simply switching the controls. can be displayed accurately.

In addition, this idea has a configuration in which the light emitting elements are arranged in one row and are driven in order by the output of the comparator, so the structure is simpler, more durable, and cheaper to manufacture than movable pointer meters. be able to.

<<Description of Embodiments>> A preferred embodiment of this invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows the front panel of the ultrasonic level meter main body (hereinafter simply referred to as the level meter) according to this invention.
A linear indicator 3 is provided in which twelve light emitting diodes 2, 2, . . . are arranged in one horizontal row.

Above and below the linear indicator 3, a percentage distance indicator 4 (0 to 50 to 100%) for displaying the actual scale and an absolute distance indicator 5 (0 to 1 ~2~3m) is attached.

Reference numeral 6 is an operator for switching between actual scale and blank scale, which will be described later, and 7 is a variable resistor knob for actual scale zero point calibration, which will be described later.

In addition, although not directly related to this idea, there are 9
10 is an upper limit setting device for setting the upper limit of the content storage level; 10 is a lower limit setting device for setting the lower limit of the content storage level; these setting devices 9,
10 is used when this level meter is used as a level switch (or meter relay). Further, 11 is a stability indicator for checking the stability of the reflected wave, and 12 is an operation indicator.

FIG. 2 is a block diagram showing the electrical configuration of the level meter according to this invention.

In the figure, reference numeral 13 is a storage tank in which the contents to be measured are stored, and an ultrasonic transducer (hereinafter simply referred to as a transducer) 14 is installed at the top of the storage tank 13 with the emission direction facing downward. installed.

In this example, from the transducer 14 to the storage tank 1
The distance L ₀ from the bottom of the tank 3 is the full scale, the distance L ₁ from the transducer 14 to the content storage surface is the empty scale, the distance Ls from the bottom of the storage tank to the storage surface is the actual scale, and L _S is the virtual maximum empty scale. I will call it.

Next, 15 is a reference pulse generation circuit, and this reference pulse generation circuit outputs minute width pulse signals (hereinafter referred to as reference pulses) at predetermined intervals.

16 is an oscillation circuit that outputs a high frequency signal over a minute period synchronized with the reference pulse each time it receives the reference pulse, and 17 is an amplifier circuit that amplifies the high frequency signal.

The output of this amplifier circuit 17 is transmitted to the transducer 1
4 toward the bottom of the storage tank 13, and the reflected waves reflected at the storage surface are received by the transducer 14.

18 is a transmitting limiter circuit for time-discriminating the received signal outputted from the transducer 14 and the transmitted signal outputted from the amplifier circuit 17 using the reference pulse, and extracts only the received signal; Reference numeral 19 denotes a receiving amplifier circuit for amplifying the receiving signal output from the transmitting wave limiter circuit 18, and 20 detects the output of the receiving amplifier circuit 19 to generate a rectangular wave (hereinafter referred to as receiving pulse). This is a detection circuit for obtaining

21 is an R-S flip-flop which is set at the rising edge of the reference pulse and reset at the rising edge of the received pulse;
A rectangular wave having a width corresponding to the empty length _L1 is outputted to the Q output terminal of the flip-flop 21 every output cycle of the reference pulse.

Reference numeral 22 denotes an integrating circuit for integrating and averaging the rectangular wave output from the R-S flip-flop 21. Therefore, the output side of this integrating circuit 22 outputs a DC voltage corresponding to the empty length _L1 . That will happen.

SW ₁ is a switch that is linked to the mode switching operator 6 described above, and the fixed side terminal a of this switch SW ₁ is supplied with the output voltage VL ₁ of the integrating circuit 22, and one of the movable side terminals b to the display drive circuit 24, which will be described later, and to the other movable side terminal c.
is similarly connected to the display drive circuit via the difference calculation circuit 23.

A virtual maximum empty length equivalent voltage VL _S corresponding to a predetermined virtual maximum empty length L S is set in the difference calculation circuit 23, and VL _S −VL 1 is set between the virtual maximum empty length equivalent voltage VL ₁ and the virtual maximum empty length equivalent _{voltage VL 1.} A difference calculation is performed and a virtual actual scale equivalent voltage V′L ₂ corresponding to the result of this calculation is output.

24 is a display driving circuit, and this display driving circuit 24 outputs the output VL ₁ (empty scale equivalent voltage) of the integrating circuit 22 obtained via the fixed terminal b or the virtual actual scale equivalent output from the difference calculation circuit 23. Voltage V′L ₂
, a series resistor group 26 that supplies different reference voltages to these comparators 25 in steps at equal intervals; A variable resistor VR for raising and lowering the value of each reference potential obtained from the above, and a switch SW connected in parallel with the variable resistor VR and turned on and off in conjunction with the mode switching operator 6. ₂
and transistors 27, 27, . . . which are turned on and off in response to the outputs of the comparators 25, 25, . . . and drive the light emitting diodes 2, 2, .

Therefore, one end of the series resistor group 26 is connected to the high voltage side reference potential _VLS , and the other end is directly grounded via the switch _SW2 or connected to the variable resistor VR.
indirectly grounded via.

In the above configuration, when the mode switching operator 6 is set to the empty side, the switch
SW ₁ is set to b side, and switch SW ₂ is ON
As a result, the lower end of the series resistor group 26 in the figure is directly connected to the zero potential point.

Therefore, the reference input terminal of each comparator 25 is applied with a voltage obtained by dividing the virtual maximum empty length equivalent voltage VL _S into 12 equal parts, and the comparison input terminal is applied with the empty length equivalent voltage corresponding to the empty length _L1 . VL ₁ is supplied to perform a comparison operation in each comparator,
On the linear indicator 3, light emitting diodes ₂ , 2, . I can do it.

On the other hand, if it is desired to display the actual scale _L2 as a percentage, the mode switching operator 6 is switched to the actual scale side. Then, in conjunction with this, switch SW ₁ is set to the terminal c side, and switch SW ₂ is set to the terminal c side.
Set to OFF side.

In this state, the actual scale _L2 of the storage tank 13 is 0~
In the range of L ₀ , linear indicator 3 is 0
Set the value of variable resistor VR to ~100%. If you try to display the actual scale as a percentage, the actual scale will become the virtual maximum empty scale, so set the variable resistor VR according to the current storage tank and display the actual scale as a percentage. I'm trying to adjust it to the correct one.
Therefore, at the reference input terminal of each comparator 25,
Apply to the value obtained by dividing VL _S −VΔL into 12 equal parts. VΔL is the voltage equivalent to the blank scale error.

From now on, the linear indicator 3 has its storage tank 1
Since the number of light emitting diodes 2, 2, etc. corresponding to the percentage value of the actual scale L ₂ corresponding to the full scale L ₀ of 3 are lit, the actual scale at that time is determined based on the percentage distance index 4 for displaying the actual scale. L ₂ can be displayed as a percentage.

In this way, according to this embodiment, the series resistance group 26
One end is connected directly to the zero potential point or connected to a variable resistor depending on the switching of the empty scale/actual scale switching operator 6.
Since it is connected to the zero potential point via VR, once the zero point calibration is performed with the controller switched to the actual scale side, zero point calibration is not required when switching to the empty scale side. Thereafter, by simply switching the operator 6, you can instantly display the absolute empty scale value and the percent actual scale value on one display without any adjustment. By directly reading the height of the tank surface with a certain level of precision, it is possible to predict overflow and facilitate maintenance, as well as by directly reading the relative amount of storage compared to when the tank is full. This can be useful for predicting and understanding absolute quantities.

<<Effects of the invention>> As is clear from the explanation of the embodiments above, according to this invention, by switching the operator to the empty side, it is possible to determine the height of the actual storage surface. It can be read directly with a certain level of precision.
In addition to facilitating overflow prediction and maintenance, by switching the control to the actual scale side, it is possible to directly read the relative storage amount to a full tank, allowing you to predict when refilling and grasp the absolute amount. It is possible to make such a flight.

Furthermore, although a common display is used,
Since the variable resistor for zero point calibration functions only when the actual scale is displayed, there is no need to recalibrate the zero point every time the display is switched, and the operation is simple.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the front panel of the main body of a level meter according to this invention, and FIG. 2 is a circuit diagram showing the electrical configuration of the same level meter. 1...Front panel, 2...Light emitting diode, 4...Percentage distance indicator for actual scale display, 5
... Absolute distance indicator for empty scale display, 6 ... Operator for switching between actual scale and empty scale, 7 ... Variable resistor knob for zero point calibration, 13 ... Storage tank, 14 ... Transducer, 15 …
... Reference pulse generation circuit, 16 ... Oscillation circuit, 17
...Amplification circuit, 18... Wave transmission limiter circuit, 19...
...Receiving amplifier circuit, 20...Detection circuit, 21...R
-S flip-flop, 22...integrator circuit, 23
... Difference calculation circuit, 24 ... Display drive circuit, 25 ...
...Comparator, 26...Series resistance group, 27...
Transistor, SW ₁ , SW ₂ ...Switch, VR...
...variable resistor.

Claims (1)

[Claim for Utility Model Registration] The transducer is periodically driven to repeatedly transmit pulsed ultrasonic waves to the storage surface, and the reflected waves from the storage surface are received, and the time required for transmitting and receiving the waves is determined by the voltage and an empty scale measuring circuit which converts this into an empty scale equivalent voltage and outputs it as an empty scale equivalent voltage, and when the empty scale/actual scale switching operator is set to the empty scale side, outputs the empty scale equivalent voltage, an output selection circuit that outputs the difference between a preset virtual maximum empty scale equivalent voltage and the empty scale equivalent voltage at that time as a virtual actual scale equivalent voltage when set to , and one end connected to a high voltage side reference potential point. The other end is connected directly to the low-voltage side reference potential point, or indirectly to the low-voltage side reference potential point via a variable resistor for actual scale zero point calibration, depending on the state of the empty scale/actual scale switching operator. a series resistor group for generating a reference potential that is selectively connected to a potential point; a comparator group that discriminates the output voltage of the output selection circuit based on a plurality of reference potentials obtained from the series resistor group; and the comparator group. A plurality of light-emitting elements driven in response to each comparator output are sequentially arranged in a row on the display panel, and an absolute distance index for empty scale display and a percentage distance index for actual scale display are arranged along the array. An ultrasonic level meter characterized by comprising: a display having the following characters written thereon; and the following.