JPH0435996Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention A-1. Field of Industrial Application This invention relates to a data transmitter that transmits measured values from counters such as water meters and gas meters to remote locations.

A-2 Prior Art Known data transmitters for transmitting measured values from a measuring instrument to a remote location are roughly divided into two types.

One method is to count and store weight values using an electronic counter, convert the stored weight values into pulse codes, and send and transmit them using the baseband method through two transmission signal lines. It is called. This had a problem with long-term reliability because the stored contents of the electronic counter could change due to the influence of external electrical noise. Furthermore, since the electronic counter relies on a built-in battery for power to operate, it not only requires the effort of constantly monitoring the battery voltage, but also requires replacement of the battery or the entire meter sensor when the battery runs out. Moreover, there was a problem in that it took time and effort to match the stored contents of the electronic counter with the numerical value of the measuring instrument after replacing it.

Furthermore, since a battery and a battery voltage monitoring circuit are required, there is another problem in that the cost is high.

The other method is called the encoder method, which is equipped with an encoder equipped with a switching contact that is linked to the number wheel that indicates the measured value of the scale, and the electrical resistance value that corresponds to the position of the number wheel of each digit. It is now possible to convert and transmit to a remote location, but three transmission signals are required to transmit the weight value of a four-digit decimal number wheel, and as the number of digits increases, the number of signals also increases. There was a problem with that. Furthermore, since it is transmitted as an electrical resistance value, an analog value comparison function is required on the reading side, resulting in a complicated structure.

The purpose of this invention is to propose a new data transmitter that can solve these problems.

B. Structure of the invention B.1 Means for solving the problem The data transmitter of this invention includes an encoder equipped with a switching contact linked to a number wheel that displays the measured value of a measuring instrument, and a contact position of this encoder. There is an output section that converts the reading into a pulse code and outputs it, and an output section that opens and closes under the control of this pulse code output.
It has a switch part that shorts or opens the main transmission signal lines, a series circuit of a diode and a capacitor connected between the signals, and a reset circuit, and the output part has a power supply terminal that receives the operating power. The reset circuit is connected to the terminal of the capacitor, and applies the voltage from the terminal of the capacitor as a reset signal to the reset terminal of the output section, and releases the reset signal when the terminal voltage of the capacitor exceeds a certain level. In addition, the output section has a function of starting operation when the reset signal is released and maintaining the input of the reset terminal in the reset release state.

R-2 Effect When a DC starting voltage is applied to the two transmission signal lines from an external reading device, a charging current flows to the capacitor through the diode, and the terminal voltage of the capacitor gradually increases at a speed corresponding to the time constant of the circuit. Rise. This terminal voltage is applied to the output section and is also applied as a reset signal to the reset terminal of the output section. Therefore, even if the terminal voltage of the capacitor rises and reaches the voltage at which the output section can operate, as long as the reset signal is applied to the reset terminal,
The output section does not start operating and is in a reset state.

When the terminal voltage of the capacitor further increases to a certain level or higher, the reset circuit releases the reset signal. At this time, the voltage applied to the power supply terminal has risen to a sufficient voltage for the output section to operate normally, so it starts operating as soon as the reset signal is released, and first resets the input to the reset terminal. Keep it in the released state. Then, it continues to operate, reading the contact position of the encoder on the number wheel, converting it into a pulse code, and outputting it. This pulse code output controls the switch section to short-circuit or open the two signal lines depending on the pulse code. In this way, baseband pulse code outputs are sent to the two signal lines.

The diode prevents current from flowing backwards from the capacitor to the signal line when the switch is closed and the signal lines are short-circuited, and the output section of the short-circuit engine operates using the power stored in the capacitor.

RO-3 EMBODIMENT In FIG. 1, numeral 1 denotes a data transmitter, which is connected to a remote reading device 2 through two transmission signal lines l1 and l2.

FIG. 2 shows an example of a numeric wheel displaying measured values of a measuring instrument (not shown). The example in the figure is a case of 4-digit display, where 3, 4, 5, 6 are 10, 10, 10, respectively.
It is a 10-digit number wheel and shows a weight value of 8463. 7 and 8 are printed wiring boards placed on the number wheels, and 10 fixed contacts corresponding to positions 0 to 9 of the number wheels are placed on both sides of the board, facing the number wheels, and rotate with the number wheels. By selecting the fixed contacts whose brushes are 0 to 9, an encoder with a switching contact linked to the number wheel is constructed. FIG. 3 shows a switching contact 12 consisting of a board 7 and a brush 9 that interlocks with the number wheel 4 facing the board 7. On the back side of the board 7, a switching contact 13 corresponding to the number wheel 3 in FIG. 2 is shown. It is provided. In addition, on the left side of the board 8 in FIG. 2, there is a switching contact 11 corresponding to the number wheel 5.
A switching contact 10 corresponding to the number wheel 6 is provided on the right side. In this way, the encoder equipped with the switching contacts ¹³ , 12, 11, and 10 that are linked to the number wheels 3, ⁴ , 5, and 6 of the 10 3 , 10 ² , 10 1 , and 10 ⁰ digits, respectively, is represented by the symbol 14 in FIG. is shown.

10 each of switching contacts 10 to 13 of encoder 14
The fixed contacts 0 to 9 are connected to the output ports OUT0 to OUT9 of the output unit 15 in FIG. 1, which will be described later, with all four digits of the fixed contacts having the corresponding numerical values connected together. In addition, the brushes of the switching contacts 13, 12, 11, and 10 for the digits of 10 ³ , 10 ² , 10 ¹ , and 10 ⁰ are connected to the input ports IN3, IN2, IN1, and IN0 of the output section 15.
are connected to each.

Again, in FIG. 1, 16 and 17 are terminals that connect the signal lines l1 and l2, and one terminal 17
is grounded. A diode 18 and a capacitor 19 are connected in series together with a resistor R2 as shown in the figure, with one end connected to the terminal 16 and the other end connected to the terminal 17. The terminals of the capacitor 19 are connected to the power supply terminals V ⁺ and V ^- of the output section 15 . R is a reset terminal of the output section 15, and it is determined that the output section operates in a reset state when the signal level of this terminal is "HIGH". The output terminal OUT10 of the output section 15 has a high impedance when the output section is in a reset state, and is maintained at a low impedance when the reset is released and operation starts, so that the operation program for the output section is determined.

Output terminal OUT11 outputs the value of encoder 14,
That is, it is a terminal through which the output section reads the measured value of the measuring instrument, converts it into a pulse code, and outputs it as a serial signal. Reference numeral 20 denotes a switch section, which consists of a transistor Tr2 whose collector is connected to terminal 16 and whose emitter is connected to terminal 17, and a resistor connected to the base of this transistor, and the output terminal is connected to this base.
OUT11 is connected.

21 is a reset circuit, Zener diode ZD
1, resistors R3 and R4, and transistor Tr1, connected as shown in the figure, and transistor Tr
A connection point C between the output terminal R1 and the resistor R4 is connected to the reset terminal R and the output terminal OUT10. The other end of the resistor R4 is connected to a connection point B between the diode 18 and the capacitor 19. Further, one end of the Zener diode ZD1 is connected to a connection point D between the resistor R2 and the diode 18.

The reading device 2 consists of a power source of voltage V, a reading start switch SW, a resistor R1, and an unconnected discrimination circuit connected to one end A of the resistor R1. When you want to read the weighing value of the scale, press the switch SW.
When it is turned to side a, a so-called starting voltage from a power source of voltage V is applied to terminals 16 and 17 of data transmitter 1 through resistor R1 and signal lines l1 and l2.
Since the charge on the capacitor 19 is initially zero, the terminal voltage of the capacitor 19 gradually increases according to a time constant determined by the resistance values of the resistors R1 and R2, the capacitance of the capacitor 19, and the like. Even if the capacitor 19 rises to a voltage that enables the output section 15 to operate, the output section 15 remains in the reset state because the reset signal is applied via the resistor R4.

When the terminal voltage of the capacitor 19 further increases and exceeds a certain value, the Zener diode ZD1 becomes conductive, and the transistor Tr1 rapidly becomes conductive.
The collector becomes "LOW" level. Therefore, when the reset signal is released and the output section 15 starts operating according to the predetermined program, first of all, the output terminal OUT10, which had been high impedance until then, becomes low impedance.
Reset terminal R is maintained at the "LOW" level.
Therefore, even if the transistor Tr1 is cut off due to a drop in the voltage at point D thereafter, the output section will not be reset again while it is in operation.
In addition, the Zener diode ZD1, together with the resistor R2, also functions as a constant voltage circuit that keeps the voltage at point D, and ultimately the voltage supplied to the output section 15, constant, so that the starting voltage from the reading device fluctuates to some extent. Also, fluctuations in the voltage supplied to the output circuit 15 are reduced. When the reset is released, output section 1
5 initiates a pre-programmed operation.

As mentioned above, output terminal OUT10 is first fixed to low impedance, and other output terminals
“LOW” is also output from OUTO11 and output ports OUT0 to OUT9. After this, the output section 15
The encoder 14 is read.

First, set only OUT0 among the output ports to “HIGH” level, and input ports IN0 to IN3.
Check the input level. By performing this operation sequentially from output port OUT0 to OUT9,
Read which output port among OUT0 to OUT9 the input ports IN0 to IN3 are connected to.

This allows you to read the 4-digit weight value 8463 displayed on the scale's number wheel. The output section 15 is
The digits are encoded and output as a constant speed social signal from the output port OUT11.

In the example, the number of each number wheel is BCD (binary coded decimal)
The digits are displayed in code, arranged in the order of 10 ³ , 10 ² , 10 ¹ , and 10 ⁰ , and output with star bits and stop bits added before and after each digit, as shown in FIG.

When a "HIGH" level output is output from the output terminal OUT11, the transistor Tr2 becomes conductive to short-circuit the signal lines l1 and l2, and the voltage at point A of the reading device 2 decreases.

Figure 5 shows points A, B, C, and D in Figure 1, and the output ports when the 4-digit number wheel displays 8463.
OUT0 to OUT9, output terminals OUT10, OUT1
1 is a timing chart showing a voltage of 1. As shown by the solid line in Figure B, the voltage applied to the power supply terminal of the output circuit 15 is maintained above a certain level by the electric charge charged in the capacitor 19 even while the serial signal (pulse code output) is being sent out. There is.

The change in the voltage at point A (received signal) shown in No. 5 is timed by a discriminator circuit (not shown),
By reading it, the 4-digit calculated value 8643 can be read by the reading device 2 at a remote location. Note that the star bit and stop bit are useful for synchronizing the timing.

When the reading is finished, the switch SW returns to side b, and all operations are completed.

Note that the output section 15 can be easily configured using a known logic circuit such as a microcomputer.

C. Effects of the invention In this invention, the measured value to be transmitted is determined by an encoder equipped with a switching contact that interlocks with the number wheel, which eliminates the drawback that electrical noise can disrupt calculations and prevent recovery. Moreover, a low-cost data transmitter that does not require batteries can be realized.

Furthermore, since it does not contain a battery, it can be easily applied to applications that require an intrinsically safe explosion-proof structure, such as gas meters, by simply adding an overvoltage prevention element.

[Brief explanation of the drawing]

The drawings show an example of this invention. Figure 1 is an electric circuit, Figure 2 is a perspective view of the number wheel of a measuring instrument, Figure 3 is a printed wiring board of an encoder, Figure 4 is an electric circuit of an encoder, and Figure 5 is a diagram of an encoder's printed wiring board. The figure is a timing chart explaining the operation of the circuit of FIG. 1. 1...Data transmitter, 2...Reader, 3,
4, 5, 6...number wheels, 10, 11, 12, 13
...Switching contact, 14...Encoder, 15...Output section, 18...Diode, 19...Capacitor, 20...Switch section, 21...Reset circuit, OUT10...Reset terminal when the output circuit starts operating. Output terminal that holds the input in the reset release state, OUT11...Pulse code output terminal, R...Reset terminal, V, V...Power supply terminal,
l1, l2...Transmission signal lines.

Claims (1)

[Scope of utility model registration request] An encoder equipped with a switching contact linked to the number wheel that displays the measured value of the scale, an output section that reads the contact position of this encoder, converts it to a pulse code and outputs it, and is controlled by this pulse code output. It has a switch section that opens and closes and short-circuits or opens two transmission signal lines, a series circuit of a diode and a capacitor connected between the signals, and a reset circuit, and the output section outputs its operating power. The receiving terminal is connected to the terminal of the capacitor, and the reset circuit applies the voltage from the terminal of the capacitor as a reset signal to the reset terminal of the output section, and resets the capacitor when the terminal voltage of the capacitor exceeds a certain level. The data transmission device has a function to release the reset signal, and further, the output section starts operating when the reset signal is released and maintains the input of the reset terminal in the reset release state. vessel.