JPH0734553B2 - Mobile electrical equipment signal transmission method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal transmission method, and more specifically, between a signal cable arranged along a trolley conductor and an antenna facing the signal cable. The present invention relates to a mobile electric device signal transmission method for transmitting information to and from a mobile device in a contactless manner.

[Prior Art] Used for automatic transportation of parts in the assembly process, automatic transportation of products between processes, or unmanned monitoring in a poor environment.
Most of the electric power supply to the automatic equipment moving on the wire is performed by sliding the trolley conductor. Also, the transmission of control information to the mobile device and the transmission of monitoring information from the mobile device are performed by a single wire arranged along the trolley conductor,
This is performed by an open transmission line such as a parallel conductor or a leaky coaxial cable and a tightly coupled signal transmission device between an antenna facing the open transmission line.

Hereinafter, a conventional tightly coupled signal transmission device will be described with reference to FIG. In the same figure, a hanger 21 having three grooves 22, 22, 22 ′ parallel to each other is fixed to a long wiring rail main body 20. Two trolley conductors 23 for supplying electric power are fixed via an insulator 24. Also, another groove
A signal leakage line 41 formed of a leaky coaxial cable or the like is embedded in the large diameter portion 22 ', and a gourd-shaped sheath 42 in which a suspension wire 43 is embedded in the small diameter portion is fixed.

Further, the trolley conductor 23 is electrically contacted with a brush 25 to which a biasing force protruding outward by a spring 26 provided in the main body 27 of the electric device is applied, and the brush 25 is provided at a position facing the signal leakage line 41. A loop antenna 30 is provided via a support member 31 with a predetermined distance maintained.

Therefore, electric power is supplied to the electric device main body 27 by the two trolley conductors 23 via the two brushes 25, and the signal supplied to the signal leakage line 41 is supplied to the electric device main body 27 via the loop antenna 30. Further, a signal is transmitted by supplying a signal from the electric device body 27 to the signal leakage line 41 via the loop antenna 30.

However, due to the inherently high noise level of the environment in which this type of equipment is installed and the noise generated when the trolley conductor slides, conventional equipment can perform stable signal transmission with moving electrical equipment. There was a problem of not having. This problem is solved by increasing the electromagnetic field strength,
It was also difficult to meet the regulation of the weak radio station (500 μV / m = 54 dBμV / m or less electric field strength at an isolation point 3 m from the antenna), which is defined by the Radio Law.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and has a sufficiently high electromagnetic field strength at a transmission distance while being strong against external noise and satisfying the regulations of the Radio Law. Moreover, it is another object of the present invention to provide a mobile electric device signal transmission method in which the received electric field strength does not change due to the movement of the electric device.

[Means and Actions for Solving Problems] In the signal transmission method of the present invention, a signal cable is arranged integrally with a wiring rail for supplying electric power to a moving electric device in a sliding manner, In the signal transmission method of transmitting an information signal to the electric device or receiving an information signal from the electric device via an antenna electrically coupled to the cable in a non-contact state, the signal cable is an insulated conductor 2 It is characterized in that the book is twisted in pairs, and the antenna is coupled to a TEM mode formed when a signal propagates between the insulated conductors.

By using the twisted pair signal cable as described above, the electromagnetic field formed around the cable is canceled and weakened, and the generation of the electromagnetic field in the external space can be suppressed. In addition, as the antenna, two loop antennas are used at an interval of (2n + 1) / 4 times the twist pitch of the insulated conductor, and as a result, the electromagnetic field strength in the length direction of the signal cable is constant. You can Further, since the signal cable is provided integrally with the wiring rail, the parallel positional relationship with the antenna does not change with the movement of the mobile electric device,
It is possible to send and receive a stable signal.

[Embodiment] An embodiment of the present invention will be described below.

First, the structure of the embodiment will be described with reference to FIG. In the same figure, a hanger 21 having three grooves 22, 22, 22 'parallel to each other is fixed to a long wiring rail main body 20, and an electric device main body 27 is fixed in the groove 22 of the hanger 21.
Two trolley conductors 23 for supplying electric power are fixed via an insulator 24. Further, a gourd-shaped sheath 42 in which the twisted pair cable 11 in which parallel conductors are twisted at a constant pitch is embedded is fixed to the other groove 22 '.

Further, the trolley conductor 23 is electrically contacted with a brush 25 to which an urging force projecting outward is applied by a spring 26 provided in the electric device body 27, and a predetermined position is provided at a position facing the twisted pair cable 11. A pair of loop antennas 32, 32 'are provided via a support member 31 with a distance maintained.

Therefore, the electric power is supplied to the electric device body 27 by the pair of trolley conductors 23 via the pair of brushes 25, and the signal supplied to the twisted pair cable 11 is supplied to the electric device body 27 via the antennas 32 and 32 '. Further, a signal is transmitted by supplying a signal from the electric device main body 27 to the twisted pair cable 11 via the antennas 32 and 32 '.

Subsequently, the embodiment will be described in more detail with reference to FIGS. 2 to 4.

FIG. 2 shows an electric field E and a magnetic field H generated by the parallel conductors 14 and 14 'in a direction perpendicular to their axes, that is, a TEM wave (transverse wave).
electromagnetic wave). Here, when the direction perpendicular to the opening faces of the parallel conductors 14 and 14 ', that is, the direction of the loop antenna 32 is used as a reference (θ = 0), the parallel conductor 1
Magnetic field strength around the unit line segment of 4,14 'ΔH ₃₂
Is ΔH ₃₂ = A (r) · B (q) · cos θ (1) However, the distance from the unit line segment of the parallel conductors 14 and 14 ′ is A
(R), the Hertz dipole efficiency B (q) of the unit line segment of the parallel conductors 14 and 14 '.

From this equation, when twisting parallel conductors at a constant pitch, it is predicted that the electromagnetic field changes sinusoidally in the axial direction.

Next, the electromagnetic field formed around the twisted pair cable 11 will be described with reference to FIG. In the figure, the parallel conductors 14 and 14 'of the twisted pair cable 11 are twisted together at a constant pitch P, and as shown in the figure, the position where the opening surface of the parallel conductors 14 and 14' faces the loop antenna 32 is used as the starting point. When the axial deviation of the loop antenna 32 is Z and the twist pitch is P, the angle α formed by the opening surfaces of the parallel conductors 14 and 14 'with the antenna 32 is α = 2πZ / P (2). Therefore, the magnetic field strength from all the line segments of the parallel conductors 14 and 14 'at the distance of the loop antenna 32 is H ₃₂ = ∫A (r) · B (q) · cos (θ + 2πZ / P) using the equation (1). dθ
… (3) Where cos (θ + 2πZ / P) = cos θ · cos (2
Transforming equation (3) with the mathematical formula of πZ / P) -sin (2πZ / P) ・ sinθ, H ₃₂ = ∫A (r) ・ B (q) ・ cosθ ・ cos (2πZ / P) d
θ-∫ A (r) ・ B (q) ・ sin θ ・ sin (2πZ / P)
dθ (4) is obtained. Since the function B (q) in the equation is a quantity proportional to the signal, it can be considered to be constant now.
Since (r) is symmetric with respect to θ, the second term on the right side of the above equation (4) becomes zero. Therefore, with C as a constant, H ₃₂ = ∫A (r) · B (q) · cos θ · cos (2πZ / P) d
It is understood that θ = C · cos (2π · Z / P) (5) is introduced and the electromagnetic field formed around the twisted pair cable changes sinusoidally in the axial direction.

Now, when the electromagnetic field changes sinusoidally in the axial direction in this way, the electromagnetic fields sufficiently far from the twist pitch P are canceled by the electromagnetic fields having opposite phases from the line segments separated by P / 2, and the electromagnetic field rapidly increases. The intensity will be attenuated. This electromagnetic field characteristic is shown in FIG. 4 together with the electromagnetic field characteristic of the conventional example.

From the above explanation, the twisted pair cable forms an electromagnetic field that has sufficient strength at the transmission distance and is rapidly attenuated at a long distance. Of the parallel conductors 14,1
It is easy to understand that by twisting 4 ', a stable transmission system can be formed without a capacity imbalance with the earth system.

However, the fact that the electromagnetic field changes sinusoidally with respect to the movement in the axial direction means that signal transmission is not performed depending on the position of the loop antenna, and this method cannot be used immediately for signal transmission. . Therefore, according to the present invention, the twist pitch of the twisted pair cable 11 is (2n + 1) / 4 times (n
This problem is solved by arranging two loop antennas 32, 32 'at intervals of = 0,1,2, ...). The value of n can be arbitrarily determined in consideration of the twist pitch or the mutual interference between the loop antennas 32 and 32 '.

Further explanation will be continued. (5) In the same manner as in the derivation of equation and obtains the 'magnetic field strength H _32' of the loop antenna _{32, H 32 '= C ·} cos (2πZ / P + π / 2) = C · sin (2πZ / P) ... (6) The output of the loop antenna 32 'for detecting this magnetic field is phase shifted by .pi. / 2 or -.pi./2 by the phase shifter 15, mixed with the output of the other loop antenna 32, and output to the terminal T. Therefore, the reception voltage V generated at the terminal T is expressed by the following equation.

V = C {cos (2πZ / P) ± j · sin (2πZ / P)} ...
(7) This expression (7) represents that the phase of the received voltage V changes with the change of Z, that is, the movement of the loop antennas 32 and 32 ', but the amplitude thereof is constant. As a result, the present invention enables not only stable signal transmission but also the determination of the position of the electric device by detecting the phase change.

It should be noted that instead of the method of phase-shifting and adding the signals obtained from one of the loop antennas as described above, the same purpose can be obtained by generating an absolute value of the signals obtained from both loop antennas by a detection means and adding them. Can be achieved. That is, Voc | cos2πZ / P | + | sin2πZ / P | (8) has a relatively constant amplitude, and it is possible to perform stable signal transmission irrespective of the position of the electric device body 27 with a simple configuration. Is possible.

[Advantages of the Invention] As described above, according to the present invention, (1) sufficient electric field strength can be obtained over a transmission distance, and electromagnetic field characteristics that are rapidly attenuated at a long distance can be obtained.

(2) Since the signal cable is provided integrally with the wiring rail, stable signal transmission / reception can be performed without changing the parallel positional relationship with the antenna with the movement of the mobile electric device.

(3) Since there is no capacity imbalance between the twisted pair cable and the ground system, stable signal transmission is possible.

(4) The induced voltage from the nearby trolley conductor and other external noise are canceled.

(5) The moving distance of the electric device can be known from the phase change of the received signal.

It is possible to provide a mobile electric device transmission method that achieves the above remarkable effect.

[Brief description of drawings]

1 is a sectional view for explaining the structure of an embodiment of the present invention, FIG. 2 is a view for explaining a TEM wave formed by parallel conductors, and FIG. 3 is a geometrical relationship between a twisted pair cable and a loop antenna. FIG. 4 is an electromagnetic field characteristic diagram, and FIG. 5 is a sectional view illustrating a structure of a conventional example. [Explanation of symbols] 11 …… twisted pair cable 14,14 ′ …… parallel conductor 15 …… phase shifter 23 …… trolley conductor 27 …… electric device main unit 32,32 ′ …… loop antenna

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-56026 (JP, A) JP-A-52-137915 (JP, A) Practical application Sho-56-150113 (JP, U)

Claims (1)

[Claims] 1. A hanger having three groove portions parallel to each other is fixed to an elongated wiring rail main body, and a trolley conductor is fixed to the two groove portions of the hanger.
A signal cable is fixed to the remaining one groove portion of the hanger, and two brushes provided on the moving electric device are attached to the electric device that moves along the long wiring rail. Electric power is supplied by sliding on the trolley conductor, and the electric cable is electrically coupled to the signal cable in a non-contact state via an antenna provided in the mobile electric device, and is electrically connected to the mobile electric device. In a signal transmission method for transmitting an information signal or receiving an information signal from the mobile electric device, the signal cable is formed by twisting two insulated conductors in pairs, while the antenna includes two loop antennas and two insulated conductors. TEMs, which are formed at intervals of (2n + 1) / 4 times the twist pitch of, and are formed when signals propagate between the insulated conductors.
A method for transmitting a signal of a mobile electric device, comprising transmitting or receiving an information signal by coupling the antenna to a mode.