GB2226637A - Multi function signal generator - Google Patents

Abstract

A permanent magnet (6) is mounted on the rotation shaft (6a) of an impeller of a gas or water meter, and an A.C. voltage is generated in relay coil (2) in response to the rotation of permanent magnet (6). The A.C. voltage is available from output terminals (E1, E2) and at the same time is used to activate light emitting diode (4) after being rectified by full-wave rectifier (3), so that an optical output signal can be supplied to an optical fiber (5). In addition, a contact ON/OFF output is available via relay contact (2a) from terminals (P1, P2). Only the latter needs an external source of power (B) to provide an output signal, the optical output on fibre (5) and the A.C. output on terminals (E1, E2) are powered solely by the voltage induced in the coil (2). <IMAGE>

Description

"MULTI-FUNCTION SIGNAL GENERATOR" This invention relates to a multi-function signal generator capable of converting information obtained by the movement of to-be-measured object into optical and electrical signals and outputting the converted signals.

Conventionally, in the gas or water supply service, for example, items of information indicating amounts of flow are collected in one place so as to simplify the operations of collection of money, maintenance and inspection. In such a centralized control system, the centralized control room is connected to the flow meters via signal transmission paths in order to transfer the flow amount signal therebetween. Recently, there has been developed a centralized control system which is highly reliable and in which an optical transmission path is used as the signal transmission path so as to suppress influence due to the spurious noise and extremely increase the amount of transfer information.

However, in the conventional optical transmission type centralized control system, it has been necessary to install a power source for generating a light signal on the transmission side or user side. Since most of the flow meters are installed in the open air, it is generally required to install exclusive power sources.

Therefore, it is extremely troublesome to maintain and control the power sources. Further, special care must be taken for safety when the power sources is installed on a gas flow meter, for example.

In order to transmit output signals of the flow meters to the centralized control system, different interface must be used as the interfaces for the output signals provided between the flow meters and the signal transmission paths because the types of output signals are different. For example, it is necessary to prepare three types of signal generators when a voltage output signal, optical output signal and contact ON/OFF output signal are generated as the output signals.

An object of this invention is to provide a multifunction signal generator which can generate electrical and optical output signals without using a power source, and which can generate at least one of an electrical output signal, optical output signal and contact ON/OFF output signal from a single signal generator of simple construction.

According to this invention, there is provided a multi-function signal generator comprising means for generating a voltage output signal in accordance with the movement of a member which responds to measurement information; means for generating a light signal in response to the voltage output signal; and means for generating at least one of the voltage output signal and optical output signal.

According to one aspect of this invention, since the voltage output signal is generated by use of the movement of a magnetic member which responds to the measurement information, it is not necessary to additionally provide a power source. Further, since the optical output signal and contact ON/OFF output signal can be derived from the voltage output signal and the output signals may be selectively output to the exterior, the signal generator can be applied irrespective of the type of the interface used between the signal generator at the user side and the signal transmission path.

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 circuit diagram of a multi-function signal generator according to one embodiment of this invention; Fig. 2 is a timing chart for illustrating the operation of the circuit shown in Fig. 1; Figs. 3 to 5 are block diagrams showing constructions according to different embodiments of this invention; and Fig. 6 is a circuit diagram of a signal generator according to still another embodiment of this invention.

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

Fig. 1 shows an embodiment wherein this invention is applied to the transmission section of a flow rate information transmission system for water meters. In Fig. 1, 1 denotes a sensor unit. Sensor unit 1 includes relay coil 2, full-wave rectifier 3 for rectifying a pulsating A.C. voltage induced in relay coil 2, light emitting diode element 4 for emitting light in response to a DC voltage rectified by rectifier 3, and optical fiber 5 for transmitting a light signal from light emitting diode element 4. Permanent magnet 6 is disposed in a position opposite to relay coil 2 of sensor unit 1. A relay switch 2a is associated with relay coil 2. A movable contact provided with a permanent magnet 2m is formed in rlay switch 2a as shown in Fig. 1.

Thus, permanent magnets 2m and 6, and relay coil 2 are electro-magnetically coupled to constitute an electricity generating element 7. Electricity generating element 7 receives rotation of permanent magnet 6 as mechanical signal M and induces an A.C. voltage across relay coil 2 according to mechanical signal M. Permanent magnet 6 is mounted on the rotation shaft 6a of an impeller (not shown) driven according to the flow of water, and rotates at a speed corresponding to the flow rate of water. When S pole of magnet 6 comes near to relay coil 2, N pole of magnet 2m attached to relay contact 2a is attracted to the S pole and set relay contact 2a into the ON state. On the contrary, when N pole of magnet 2m comes, relay contact 2a is set into the OFF state. Full-wave rectifier 3 is constituted by connecting four rectifying diodes 8a, 8b, 8c and 8d in a bridge form.A.C. input terminals of rectifier 3 are connected to two ends of relay coil 2 and D.C. output terminals thereof are connected to light emitting diode element 4. Light emitting diode element 4 emits light to the input end of optical fiber 5. The light incident on the optical fiber 5 is transmitted to the remote centralized control section which is the receiving side via optical fiber 5. That is, electricity generating element 7, rectifier 3 and light emitting diode element 4 are combined to constitute an optical transmitter of sensor unit 1.

Further, sensor until 1 has voltage output terminals El and E2 for extracting voltage output Vout and output terminals P1 and P2 for extracting contact ON/OFF output. Voltage output terminals El and E2 are respectively connected to two ends of relay coil 2 so that A.C. output vout induced in relay coil 2 due to ON/OFF operations of relay contact 2a can be obtained from output terminals El and E2.

Output terminals P1 and P2 are connected to two ends of relay contact 2a. Therefore, when an external battery B is connected between output terminals P1 and P2 as shown in Fig. 1, a pulse output is generated in response to the operation of relay contact 2a whose contact position is controlled by the positions of N and S poles of magnet 6 and can be derived between output terminals P1 and P2.

There is now described an operation of the embodiment of Fig. 1 with reference to the timing chart of Fig. 2.

As magnet 6 rotates according to the flow rate of water flowing in a water pipe, magnetic poles N and S alternately come to a position close to relay coil 2 and magnet 2m as shown in Fig. 2(a). Thus, a pulsating A.C. voltage shown in Fig. 2(d) is induced in relay coil 2 according to the rotation of magnet 6 and current I1 of both polarities shown in Fig. 2(b) flows. Current I1 alternately flows in the path of relay coil diode 8a < 1ight emitting diode element diode 8relay coil 2 and in the path of relay coil 2diode 8d- > light emitting diode element diode 8relay coil 2. As a result, current I2 obtained by rectifying current I1 as shown in Fig. 2(c) flows in light emitting diode element 4. In this way, light emitting diode element 4 emitts light in response to current I2 and thus supplies å light signal to optical fiber 5. As described before, repetition rate of the light signal represents the flow rate of water. At the same time, voltage output signal Vout of Fig. 2(d) is derived from terminals El and E2, and a contact ON/OFF pulse signal is derived from terminals P1 and P2 as shown in Fig. 2(e).

In this way, according to the embodiment, a multifunction signal generator of simple construction and using no power source can be provided. In this case, the number of items of transmission information can be increased by rectifying the voltage of two polarities induced in relay coil 2, thus improving the precision of measurement.

This invention is not limited to the above embodiment.

The following embodiments of Figs. 3-5 have modification of rectifier 3 shown in Fig. 1 and remaining portions are similarly provided as in the case of Fig. 1 embodiment. Therefore, only the modified portions are shown in Figs. 3-5 for the sake of simplicity.

For example, as shown in Fig. 3, the construction can be further simplified by constituting rectifier 11 by connecting two rectifier diodes 12a and 12b and two light emitting diodes 13a and 13b in a bridge form.

Further, the aforementioned effect can be obtained by connecting two light emitting diodes 15a and 15b with different polarities to attain the rectification effect without using rectifier diodes as shown in Fig. 4.

Further, in a case where increase in the amount of transmission information is not so important, the signal generator P can be formed with simple construction by connecting electricity generating element 7 in series with light emitting diode 17 so as to be activated only by positive voltage components of the A.C. voltage induced in a relay coil provided in electricity generating element 7.

The signal generator P in each of the embodiments can be disposed in a small space in the water or gas flow meter when it is compactly packaged.

Further, in the above embodiments, electricity generating element 7 which causes electromagnetic induction is used. However, it is possible to use another type of electricity generating element such as piezoelectric element which causes the piezoelectric effect.

It is also possible to another type of light emitting element such as a discharge tube instead of the light emitting diode element.

Fig. 6 is a circuit diagram showing still another embodiment of this invention. In Fig. 6, portions which corresponds to those in Fig. 1 are denoted by the same reference numerals. When the permanent magnet mounted on the rotation shaft of the impeller of the water flow meter rotates according to the flow rate of water in the same manner as in the case of Fig. 1, mechanical signal M corresponding to the flow rate is input to electricity generating element 7. Like the electricity generating element shown in Fig. 1, relay coil 2 is provided in electricity generating element 7, and C contact switch 2b is connected to relay coil 2.

C contact switch 2b has one movable contact C1 and two fixed contacts C2 and C3 which are respectively connected to contact ON/OFF output terminals P2, P1 and P3 of sensor unit'la. A permanent magnet 2m is attached to movable contact Cl.

Like the embodiment of Fig. 4, two light emitting diodes 15a and 15b are connected to antiparallel fashion between two ends of relay coil 2 via a resistor R.

In Fig. 6, for example, when the S pole of a permanent magnet (not shown) comes to a position close to relay coil 2, magnet 2m and movable contact C1 is set to fixed contact C2 as shown in Fig. 6 and kept in this contact position. When the permanent magnet further rotates and the N pole thereof comes to the position close to relay coil 2, movable contact C1 is set to fixed contact C3 and kept in this contact position.

In this way, terminal P2 is alternately connected to terminals P1 and P3 via C contact switch 2b.

As described above, according to this invention, a contact output signal, voltage output signal and optical output signal each representing flow rate of a fluid can be formed in a single signal generator of simple construction, and therefore the signal generator can be used for any type of interface for connecting remote fluid meter and a control center.

Further, since the voltage output signal can be derived from a single relay of small size and large circuit parts are not used, a multi-function signal generator of extremely small size can be attained. If optical fiber 5 used in the embodiments of Figs. 1 and 6 is formed so as to be connected to a connector disposed on the output section of sensor unit 1 (la), the connection cable can be formed without protruding from the signal generator and therefore the treatment of the signal generator may become easy.

Claims (9)

Claims:

1. A multi-function signal generator comprising: means for generating a voltage output signal in accordance with movement of a member which responds to information to be measured; means for generating a light signal in response to the voltage output signal; and means for generating at least one of the voltage output signal and optical output signal.

2. A signal generator according to claim 1, wherein said voltage output signal generating means includes a permanent magnet responding to movement of an object to-be-measured; and coil means electromagnetically coupled with said permanent magnet.

3. A signal generator according to claim 1, wherein said voltage output signal generating means includes a piezoelectric element for generating a voltage signal according to movement of an object to-be-measured.

4. A signal generator according to claim 2, further comprising contact means for generating a contact ON/OFF output signal in response to the voltage output signal, the ON/OFF position of said contact means being controlled according to an excitation state of said coil means.

5. A signal generator according to claim 4, wherein said contact means includes a C contact switch mechanism.

6. A signal generator according to claim 1, wherein said light signal generating means includes at least one light emitting diode element energized by the voltage output signal; and an optical fiber for transmitting a light signal supplied from said light emitting diode element.

7. A signal generator according to claim 6, wherein said light signal generating means includes a rectifier circuit for full-wave rectifying and A.C.

voltage generated from said voltage output signal generating means and said light emitting diode element is connected to the D.C. output terminals of said full-wave rectifier circuit and energized by the full-wave rectified output from said rectifier circuit.

8. A signal genertator according to claim 7, wherein said full-wave rectifier circuit includes four diode elements at least one of which is a light emitting diode.

9. A multi-function signal generator, substantially as hereinbefore described with reference to the accompanying drawings.