GB2226668A - Meter reading system - Google Patents

Abstract

A flow measurement output of a water meter (11) is transmitted to a driven shaft (13a) via a magnetic coupler (12), and an instantaneous flow output can be derived at a terminal (71) via a slit plate (67) and a photoelectric converting element (68a, 68b) when the driven shaft (13a) rotates. The integrated flow is measured by an integrating counter connected to the driven shaft (13a), and the rotational positions of character wheels of respective digits are represented by the positions of brush contacts (16a to 16d). The positions of the brush contacts (16a to 16d) are converted into voltages by a series of resistors (18-0 to 18-9) and transmitted to a receiving side (2) via a two-core cable (3). A timing circuit (50) controls four switches (34, 35, 37, 38) so power from sources (36, 39-41) is sent to the transmitting side (1) to control the position of a switch (20) and read each digit in turn. The count is latched (47) and displayed (49). <IMAGE>

Description

"SIGNAL READING SYSTEM" This invention relates to a signal reading system capable of reading data of accumulated and/or instantaneous amount of water, gas or the like used by each user collectively at a central totalizing station or on the user side if necessary.

For example, when the amount of gas or water used in each of the house units of an apartment house, mixed building house and each business company is checked, it will be extremely convenient if the indicators are centralized in one place. Various flow meters which are conventionally called remote measurement type flow meters have been proposed to meet the above requirement.

With the remote measurement type flow meters, mechanical signals which are obtained by the flow detectors are converted into electrical signals which are in turn transferred to indicators separated from the detectors.

Then, the indicators are driven by the received electrical signals.

However, in this type of conventional remote measurement type flow meter, it is necessary to use at least five lead lines in order to connect the detector section with the indicator section or connect the transmitter section with the receiving section when 3-digit representation is used. Therefore, if the distance between the detector section and indicator section in several hundreds meter, installation free for the lead lines will extremely increase and the installation becomes complex.

An object of this invention is to provide a signal reading system which can transmit a measurement signal of plural digits from a detector placed at a remote position to a totalizing center via signal transmission lines of the number smaller than the number of digits, can be installed at a low cost, and permits the signal to be easily extracted at the totalizing center.

According to this invention, there is provided a signal reading system comprising a transmission section including a driven shaft which is connected to be rotated by means of an output shaft of a flow meter, counting means connected to the driven shaft, for measuring the amount of flow represented by the rotation amount of the driven shaft, and signal generating means for generating a flow output signal corresponding to the measurement of the counter; and a receiving section for receiving the flow output signal from the transmission section and including means for supplying a power source to the signal generating means, means for receiving the flow output signal obtained by the supply of power source and visually displaying the amount of flow, and means for controlling the power source supplying means and visual displaying means.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a block diagram showing the circuit construction of the whole system according to one embodiment of this invention; Fig. 2 is a top plan view showing the mechanical construction of a flow detector shown in Fig. 1; Fig. 3 is a partly sectional view showing the construction of an instantaneous flow signal output section shown in Fig. 2; Fig. 4 is a timing chart showing the operation of the embodiment of Fig. 1; and Figs. 5 and 6 are block diagrams schematically showing the constructions of systems according to different embodiments.

There will now be described an embodiment of this invention with reference to the accompanying drawings.

Fig. 1 shows the whole construction of a signal reading system according to the first embodiment in which this invention is applied to a water meter. The flow meter includes transmitter section 1 placed at a remote position, receiving section 2 placed at the totalizing center to receive a signal from transmitter section 1, and corer cable 3 for electrically connecting receiving section 2 and transmitter section 1 to each other.

Transmitter section 1 is constructed as follows.

That is, rotation shaft lla of an impeller of flow sensor 11 is connected to driving shaft 13a of mechanical counter 13 via magnetic coupler 12 formed of a pair of permanent magnets 12a and 12b. Rotation shaft 13a rotates at a speed proportional to the flow rate of water 10, and is connected to instantaneous flow signal output section 5 as will be described later. Counter 13 has rotation type indicators 14a, 14b, 14c and 14d of four digits as shown in Fig. 2. The combination of the numerals indicated by the indicators corresponds to a four-digit integrated or accumulated flow amount.

Indicator 14a of "1" digit is connected to rotation shaft 17 so as to be rotated relative to switching contact 16a of rotary section switch 15a. That is, indicator 14a is used as the lowest-digit (units digit) indicator and the shaft of indicator 14a is connected to rotation shaft 17 of rotary selection switch 15.

Rotary selection switches 15a to 15d each include tenfixed contacts "0" to "9" corresponding to the numeric representation of each of indicators 14a to 14d.

Corresponding fixed contacts of the respective rotary selection switches 15a to 15d are commonly connected.

Resistors 18-1 to 18-9 which are set to be slightly larger in this order are respectively connected between corresponding adjacent two of the fixed contacts. Fixed contact "0" is connected to output terminal A via resistor 18-0. Switching contacts 16a to 16d of rotary switches 15a to 15d are connected to terminals 21a to 21d or selection switch 20 via respective diodes 19a to 19d with the polarities shown in Fig. 1. Selection switch 20 is used to form part of bi-directional latching relay 23 as will be described later, and includes switching contacts 22a and 22b. Switching contact 22a is selectively connected to terminals 21a and 21c, and switching contact 22b is selectively connected to terminals 21b and 21d. Switching contacts 22a and 22b are commonly connected to output terminal B.

Driving coils 24a and 24b of bi-directional latching relay 23 are connected in parallel between terminals A and B via zener diodes 25a and 25b with the polarities shown in Fig. 1. In Fig. 1, 26 denotes an arrester.

Now, the construction of the flow detector section is explained with reference to Figs. 2 and 3. As shown in Fig. 2, worm gear 60 is mounted on rotation shaft 13a on which driven magnet 12b shown in Fig. 1 is mounted.

Worm gear 60 is engaged with worm wheel 61 which is rotatably engaged with main shaft 17. Cam wheel 62 is integrally formed with worm wheel 61, and leaf spring 63 is pressed against cam wheel 62.

Ten conductive belts 64a to 64j insulated from one another are formed as numeral representation lines on the surface of main shaft 17 to extend in an axial direction. For example, belts 64a and 64j are respectively set to numerals "0" and "9". A printed board (not shown) on which resistors 18-0 to 18-9 shown in Fig. 1 are formed is fixed on the left end of main shaft 17. That is, as shown in Fig. 1, one end of belt 64a is connected to a connection node between resistors 18-0 and 18-1, belt 64b is connected to a connection node between resistors 18-1 and 18-2, and one end of resistor 18-9 is connected to one end of belt 64j.

As shown in Fig. 2, indicator or character wheel 14a of "1" digit is rotatably engaged with main shaft 17 so as to be rotated together with cam wheel 62.

Conductive ring 65a is mounted to rotate together with character wheel 14a, and brush 16a mounted on supporting plate 67 is made in contact with conductive ring 65a.

Brush 16a is connected to terminal 66a. Although not shown, contacts are formed in conductive ring 65a in contact with main shaft 17. The contacts are set so as to sequentially come into contact with conductive belts 64a to 64j on main shaft 17 when character wheel 14a rotates around main shaft 17. Likewise, conductive rings 65b to 65d are mounted on respective character wheels 14b to 14d, and brushes 16b to 16d are set in slidable contact on the respective conductive rings.

Although not shown, digit feeding wheels are engaged with respective character wheels 14a to 14d. Therefore, each time character wheel 14a rotates once, character wheel 14b of "10" digit is rotated by one one graduation, thus making it possible to indicate 4-digit numeral by character wheels 14a to 14d. Terminals 66a to 66d are respectively connected to the other ends of diodes l9a to 19d of Fig. 1.

Slit plate 67 is mounted together with worm gear 60 on driving shaft of counter 13. Slit plate 67 has a plurality of slits 67a, 67b, ---, 67n formed in the peripheral portion thereof. Instantaneous flow signal output device 68 is mounted on frame 69 to partly sandwich that portion of slit plate 67 in which slits 67a to 67n are formed. Output device 68 has LED 68a and phototransistor 68b which are arranged on frame 69 to face each other with slit 67c, for example, disposed therebetween as shown in Fig. 3.

LED 68a is connected to power source terminal 70 as shown in Fig. 1 and phototransistor 68b is connected to instantaneous flow output terminal 71.

One end of two-core cable 3 is connected to output terminal A and B of transmission section 1, and the other terminal of two-core cable 3 is connected to input terminals C and D of receiving section 2.

Input terminals C and D of receiving section 2 are connected to input terminals of interlocked switch 31.

One output terminal 32 of interlocked switch 31 is grounded via switch 34 and via switch 35 and D.C. power source 36 with the polarity shown in Fig. 1. The other output terminal 33 of interlocked switch 31 is grounded via switch 37 and via switch 38 and D.C. power source 39 with the polarity shown in Fig. 2. Output terminals 32 and 33 are grounded via constant current sources 40 and 41 and connected to voltage adder 42 whose output terminal is connected to one input terminal of each of comparators 43-0 to 43-9. The other input terminal of each of comparators 43-0 to 43-9 is connected to receive a corresponding one of voltages generated by supplying current from constant current source 44 via 11 resistors 45-0 to 45-10 of the same resistance. Constant current sources 40, 41 and 44 are operated on the same reference power source to output the same current.

Outputs from comparators 43-9 to 43-9 are supplied to voltage-binary signal converter 46 and converted to binary signals which are in turn supplied to and latched by latching circuits 47a to 47d provided for respective digits. Outputs of latching circuits 47a to 47d are supplied to display signal converters 48a to 48d, and outputs of display signal converters 48a to 48d are supplied to 7-segment display units 49a to 49d. With this construction, switching states of switches 34, 35, 37 and 38 are latching operation of latching circuits 47a to 47d are controlled by means of timing circuit 50 as will be described later.

Now, the operation of the above embodiment is explained.

When water 10 is used by the user and flows to rotate the shaft of flow sensor 11, indicators 14a to 14d of counter 13 are rotated, thereby rotating selection brush contacts 16a to 16d of rotary selection switches 15a to 15d. Assume now that the values indicated by indicators 14a to 14d are "9", "6", "8" and "1" from the upper digit. Then, selecting brush contact 16d of rotary selection switch 15d of fourth-digit is set on the ninth fixed contact, selecting brush contact 16c of rotary selection switch 15c of third-digit is set on the sixth fixed contact, and selecting brush contacts 16bn and 16a of rotary selection switches 16b and 15a of second- and first-digits are set on the eighth and first fixed contacts.

When switch 31 of receiving section 2 is turned on to set timing circuit 50 to the operative condition at timing to as shown in Fig. 4, timing circuit 50 turns on switches 34 and 38. The turn-on of switches 34 and 38 causes an output voltage of D.C. power source 39 to be applied between output terminals A and B of transmission section 1. When the applied voltage is higher than the zener voltage of zener diode 25a, one of the driving coils of bi-directional latching relay 23, for example, driving coil 24a is energized. As a result, selection contacts 22a and 22b of selection switch 20 are set to the contact positions opposite to those shown in Fig. 1, and selection contacts 22a and 22b are respectively set in contact with terminals 21a and 21b.

Timing circuit 50 controls switch 38 to keep it on only for a brief time, and turns off it at timing tl as shown in Fig. 4. The turn-off of switch 38 sets up a condition in which only constant current source 41 is connected between output terminals A and B or transmission section 1, thus causing constant current I to flow into transmission section 1. Assume now that the value of the constant current is set so that the voltage generated between output terminals A and B of transmission section 1 by supplying the constant current when impedance as viewed from output terminals A and B is maximum may be set to be lower than the zener voltage.Then, supplied constant current I tends to flow via resistors 18-0 to 18-9 into selection contacts 16a to 16d of rotary selection switches 15a and 15b. In this case, however, since diode 19b is reversely connected to selection contact 16b of rotary selection switch 15b, constant current I flows via output terminal A, resistors 18-0 and 18-1, the first terminal and selection contact 16a of rotary selection switch 15a, diode 19a and output terminal B. As a result, voltage of 2RI will appear between input terminals C and D of receiving section 2 as shown in Fig. 4f if the resistances of resistors 18-0 and 18-1 are R. The voltage is applied to comparators 43-0 to 43-10 via voltage adder 42 and converted into a digital signal by voltage-binary signal converter 46. A this time, the converted value becomes "1" when represented by the decimal rotation.

Then, timing circuit 50 supplies a latch signal to latching circuit 47a at timing t2. Thus, display unit 49a displays "1". That is, the same value as that of first-digit (units digit) indicator 14a of counter 13 is displayed.

At timing t3, circuit 50 turns off switch 34 and turn on switch 37. As a result, constant current source 40 is connected between output terminals A and B of transmission section 1, causing current I to flow from output terminal B to output terminal A. That is, constant current I flows via output terminal B, diode 19b, selection contact 16b and the eighth terminal of rotary selection switch 15b, resistors 18-8, 18-7, ---, 18-1 and output terminal B. As s result, voltage of 9RI appears between input terminals C and D of receiving section 2 as shown in Fig. 4g when the resistance of each resistor is R. The voltage is converted into a binary signal as described before, and the value becomes "8" when represented by the decimal rotation. Then, timing circuit 50 supplies a latch signal to latching circuit 47b at timing t4. In this way, "8" is displayed on display unit 49b, that is, the same value as that of second-digit (ten's digit) indicator 14b of counter 13 is displayed.

At timing t5, timing circuit 50 turns on switch 35 only for a brief time. The turn-on of switch 35 causes a voltage higher than the zener voltage of zener diode 25b to be applied between output terminals A and B of transmission section 1 with output terminal B set on the positive side. As a result, the other driving coil 24b of bi-directional latching relay 23 is energized to hole selection switch 20 in the position shown in Fig. 2. At timing t6, switch is turned off. Since, at this time, constant current source 40 is connected between output terminals A and B of transmission section 1, constant current I flows via output terminal B, diode 19c, selection contact 16c of rotary selection switch 15c, resistors 18-6, 18-5, ---, 18-1, 18-0 and output terminal A in transmission section 1. As a result, voltage of 7RI appears between input terminal C and D.The voltage is converted into a binary signal as described before and the converted value becomes "6" when represented by the decimal notation. Then, timing circuit 50 supplies a latch signal to latching circuit 47c at timing t7. In this way, "6" is displayed on display unit 49c, that is, the same value as that of third-digit (hundred's digit) indicator 14c of counter 13 is displayed.

At timing t8, timing circuit 50 turns off switch 37 and turn on switch 34. As a result, constant current source 41 is connected between output terminals A and B of transmission section 1, causing constant current to flow from output terminal A to output terminal B in transmission section 1 via resistors 18-0, 18-1, ---, 18-9, the ninth fixed contact and selection contact 16d of rotary selection switch 15d, and diode 19d. As a result, voltage of 1ORI appears between input terminals C and D of receiving section 2. The voltage is converted into a binary signal as described before, and the value becomes "9" when represented by the decimal notation. Then, timing circuit 50 supplies a latch signal to latching circuit 47d at timing t9.In this way, "9" is displayed on display unit 49d, that is, the same value as that of fourth-digit (thousand's digit) indicator 14d of counter 13 is displayed. Thus, the indications in all the digits of counter 13 are displayed on receiving section 2. Then, timing circuit 50 repeatedly effects a sequence of control operations as described above until switch 31 is turned off.

As described above, bi-directional relay 23 and four diodes 19a to l9d are connected in transmission circuit 1 in the above-described relation to control the holding state of latching relay 23 and the direction of constant current I. Therefore, substantially four impedance signals derived from the four resistors of transmission section 1 can be transmitted to receiving section 2 via two-core cable 3. As a result, it becomes possible to remarkably reduce the number of lead lines connecting the detector and the measuring section when the remote measurement system is used. Thus, when the centralized measuring system is used for the apartment houses and mixed building houses, the installation fee can be significantly reduced.

In the above embodiment, the output section capable of measuring the instantaneous flow amount is placed on the transmitter side or user side. For example, when it is informed from the user that water leak or gas leak has occurred, the service man goes to a corresponding place to connect a power source to power source terminal 70 shown in Fig. 1. Thus, LED 68a is energized to emit light and a signal representing the instantaneous flow amount obtained via slit plate 67 is supplied to phototransistor 689b. A detector (not shown) is connected to the output terminal of phototransistor 68b so as to measure the instantaneous flow amount.For example, in the case of gas leak, the instantaneous flow amount on user side can be detected at once and therefore it is easily determined that the gas leak occurs in the user's house or in a place between the outdoor meter'll and the main gas pipe, thus effectively attaining the security.

In the embodiment of Fig. 1, a series circuit of 10 resistors 18-0 to 18-9 of the same resistance is used to permit the counter indications to be read on the receiving side. However, when two resistor series are used, the constructions of selection switch 20 and measuring circuit 2a can be more simplified.

Fig. 5 shown an embodiment based on the abovedescribed conception. In Fig. 5, portions which correspond to those of Fig. 1 are denoted by the same numerals. In Fig. 5, a series circuit of resistors 18-10 to 18-19 is used for digits of "1" and "100", and a series circuit of resistors 18-20 to 18-29 is used for digits of "10" and "1000". Brush contacts 16a and 16b are provided for resistor series 18-10 to 18-19, and brush contacts 16c and 16d are provided for resistor series 18-20 18-29. Brush contacts 16a and 16b are connected to contact 20b of digit selection switch 20a via respective diodes 19a and 19b having opposite polarities, and brush contacts 16c and 16d are connected to the other contact 20c of digit selection switch 20a via respective diodes 19c and 19d.Digit selection switch 20a is switched between contacts 20b and 20c by means of bi-directional switching relay 23 for digit selection.

The operation of the embodiment of Fig. 5 is substantially the same as that of the embodiment of Fig. 1, and the more detail explanation will not be necessary. In this case, however, the flow amount is "1538".

Fig. 6 is a construction view of another embodiment of this invention. The embodiment is similar to those of Fig. 1 and 5 except that transmission cable 3b is constituted by three lines L1 to L3. In this case, it is possible to provide digit selection switch 20a is center 2b so that the operator can manually select it.

That is, line L2 is connected between contact 20b and brush contacts 16a and 16b via diodes l9a and 19b.

Line 3 is connected between contact 20c and brush contacts 16c and 16d via diodes l9c and 19d. The third line L1 is connected to one end of each of the two resistor series. In the embodiment of Fig. 6, the selection of the resistor series is effected by use of switch 20a of receiving section 2b. The embodiments of Figs. 5 and 6 may be formed to have an instantaneous flow measuring section 5 in the same manner as in the embodiment of Fig. 1.

This invention is not limited to the remote measurement type flow meter. For example, this invention can be applied to a remote measurement type temperature measuring device utilizing variation in the resistance according to the temperature change or to the case where breaking of wire in instruments is detected at a remote place. Further, it is possible to use two latching relays so as to effect the bi-directional operations.

As described above, according to this invention, a signal reading system can be provided in which four impedance signals can be transmitted to a remote place by use of two- or three-core cable and which is significantly effective when applied to various remote measurement type devices.

Claims (7)

What is claimed is:

1. A signal reading system comprising: a transmission section including a driven shaft which is connected to be rotated by means of an output shaft of a flow meter, counter means connected to said driven shaft, for measuring the amount of flow represetned by the rotation amount of said driven shaft, and signal generating means for generating a flow output signal corresponding to the measurement of the counter means; and a receiving section for receiving the flow output signal from said transmission section and including means for supplying a power source to the signal generating means, means for receiving the flow output signal obtained by the supply of power source and visually displaying the amount of flow, and means for controlling said power source supplying means and visual displaying means.

2. A signal reading system according to claim 1, further comprising a lit place mounted on said driven shaft; and means for detecting the rotation of said alit place by use of a plurality of slits formed in said slit plate.

3. A signal reading system according to claim 1 or 2, wherein said counter means includes a main shaft and plural-digit displaying character wheels rotatably engaged with said main shaft and rotated according to the rotation of said driven shaft; and said signal generating means includes means for extracting, via said main shaft, a position signal indicting the rotational position of each of said character wheels with respect to said main shaft, and a resistor encoder for extracting and electrical signal corresponding to the positional signal as the flow output signal for each digit.

4. A signal reading system according to claim 1 or 2, further comprising a two- or three-core cable connected between said transmission section and said receiving section.

5. A signal reading system according to claim 3, wherein said resistor encoder includes a first resistor series having 10 series-connected resistor elements of the same resistance; and means for deriving an electrical signal by connecting a selected number or resistor elements to said power source in response to a position signal derived based on the rotational position of said character wheels; and said control means includes means for connecting said first resistor series to power sources of preset levels and polarities in accordance with the rotational position of said character wheels or respective digits.

6. A signal reading system according to claim 3, wherein said resistor encoder includes first and second resistor series each having 10 series-connected resistor elements of the same resistance; and means for connecting said first resistor series to a first group of character wheels included in said character wheels and connecting said second resistor series to a second group of the remaining character wheels of said character wheels; and said control means includes means for supplying current of preset polarity to a connected one of said first and second resistor series.

7. A signal reading system, substantially as hereinbefore described with reference to the accompanying drawings.