JP2599438B2 - How to measure the distance between metal wires - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal cable for measuring a center distance of each metal wire in a flat cable formed by arranging a plurality of metal wires in parallel in a flat strip-shaped insulator. The present invention relates to a method for measuring an inter-distance.

(Prior Art) With the spread of electronic devices such as OA devices, flat cables 40 as shown in FIG. 15 are being used. The flat cable 40 has a large number of, for example, eight metal wires (hereinafter referred to as core conductors) 41 to 48 which are arranged in parallel at small intervals in parallel, and are integrally insulated by an insulating member 49 to form a strip shape. It was done. As the flat cable, there are various types such as those in which the thickness of each core conductor in one flat cable is the same or different depending on the purpose of use. For example, in the flat cable 40 shown in FIG. 15, the thickness of the core conductors 41 to 48 is different, and the thick wire conductors 41 and 42 are used for power supply and used for signal transmission of the thin core conductors 43 to 48.

In order to automate the connection between such a large number of parallel cored conductors and the connector, it is necessary that the center distance (pitch) of the cored conductors to be arranged in parallel is accurately set to a specified value. Therefore, it is necessary to measure the dimensions of these parts with high precision, and they are usually measured visually.

(Problems to be Solved by the Invention) However, it is extremely difficult to measure the center distance of a large number of core conductors arranged at small intervals by visual observation, and the work efficiency is low.

As a method for electrically detecting the center distance of the parallel core conductor, an excitation coil and a reception coil are arranged to face each other to form a magnetic head, the excitation coil is excited by an alternating current, and the parallel core conductor is placed in a gap. Is moved to detect the change in electromotive force induced in the receiving coil when each core conductor crosses the magnetic field, thereby detecting the center distance of each core conductor.

In order to increase the detection sensitivity of the magnetic head and reduce the effect of other core conductors adjacent at a small interval, it is necessary to converge the magnetic flux to a thin core conductor, and the magnetic material that winds the coil It is necessary to process the tip of the ferrite core to be used very thinly (0.5 mm or less in diameter). However, since the ferrite core is a brittle and hard material, its processing is extremely difficult.

Further, in the conventional signal processing method, for example, when each of the core conductors 41 to 48 of the flat cable 40 as shown in FIG. 15 is detected, the detected signal is detected, full-wave rectified and the position signal is detected. Because the position signal waveform changes as shown by e ₁ to e _{8 in} FIG. 16, particularly,
The waveforms of the position signals e ₁ and e ₂ of the thick core conductors 41 and 42 have two peaks and become complicated. As a result, these core conductors 41,
It is difficult to accurately detect the center position of 42. In addition, when performing multi-product production on the same manufacturing line, it is necessary to measure the dimensions of various types of flat cables with one measuring device, and it is not possible to accurately measure the center distance of the core conductors having different thicknesses. It is difficult, and there is a problem that the calculation software of the computer of the signal processing circuit becomes complicated.

The present invention has been made in view of the above points, and even when the thickness of each core conductor of a flat cable is different, the center position of each core conductor is detected well, and the center distance of each core conductor is determined. It is an object of the present invention to provide a method for measuring the distance between metal wires, which can accurately measure the distance between metal wires.

(Means for Solving the Problems) According to the present invention, in order to achieve the above object, a shield plate having a slit is mounted on each coil of a magnetic head in which an exciting coil and a receiving coil are arranged to face each other. Forming an alternating magnetic field, moving the non-uniform alternating magnetic field across a flat cable in which a number of metal wires are insulated and juxtaposed, and detecting a change in the output signal of the receiving coil at the center position of each metal wire; Forming a sampling pulse signal based on an AC exciting current for exciting the exciting coil, sampling and holding the signals sequentially output from the receiving coil at the center position of each metal by the sampling pulse signal, and sequentially setting the position signal of each metal wire; And the center distance of each metal wire of the flat cable is measured based on these position signals.

(Operation) When the flat cable is traversed in the non-uniform alternating magnetic field of the magnetic head, the change of the electromotive force induced in the receiving coil when each metal wire passes through the slit position of the shielding plate is maximized. On the other hand, the output signal of the receiving coil is sampled by a sampling pulse signal formed by an alternating magnetic current to obtain a signal near a substantially peak value, that is, a position signal at the center position of the metal wire to be detected.

These position signals are sequentially taken into a signal processing circuit to obtain position signals at the center position of each metal wire, and the center distance of each metal wire of the flat cable is measured based on these position signals. This makes it possible to accurately and easily measure the center distance of each metal wire in flat cables having different thicknesses of the metal wires.

Embodiment An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an outline of a sensor for detecting a core conductor for implementing a method of measuring a distance between metal wires of a flat cable. The sensor 1 includes two magnetic heads 3 and 4, one of which is one. In the magnetic head 3, cylindrical magnetic poles 6, 6 are integrally formed on the inner surface of the open end of a core 5 having a substantially U-shape and a rectangular cross section, and each end face of these magnetic poles 6, 6 has a slight gap G. They are arranged opposite to each other. An exciting coil 7 and a receiving coil 8 (FIG. 3) are wound around the ends of the magnetic poles 6, 6, respectively. The other magnetic head 4 is also formed in the same manner as the magnetic head 3, and an excitation coil 12 and a reception coil 13 (FIG. 5) are wound around the magnetic poles 11, 11 at the end of the core 10.

The excitation coil 7 and the reception coil 8 of the magnetic head 3 are provided with shielding plates 14 and 15, respectively.
13 is provided with shielding plates 16 and 17. The shielding plate 14 is the second
As shown in the figure, the bottomed cylindrical body is divided into two parts 14a and 14b in the axial direction, and these are bonded and fixed again with an adhesive to form a bottomed cylinder again. A slit 14d (FIGS. 1 and 6) is formed. Therefore, the width d of the slit 14d is set to be extremely narrow, about the thickness of the adhesive film. The shielding plate 15 is formed similarly to the shielding plate 14 as shown in FIG. 2 (b).
Each shield plate of the exciting coil 12 and the receiving coil 13 of the magnetic head 4
16 and 17 are formed in exactly the same manner as the shielding plates 14 and 15. These shielding plates 14 to 17 are formed of, for example, a copper thin plate having good electrical conductivity.

As shown in FIGS. 1 and 3, the shielding plates 14 and 15 are fitted around the excitation coil 7 and the receiving coil 8 at the tips of the magnetic poles 6 and 6, respectively. Slit 14
d and 15d are opposed to each other, are in the same vertical plane, and are arranged along the width direction of the side portion 5a of the core 5. Shield
Reference numerals 16 and 17 are attached to the excitation coil 12 and the reception coil 13 at the tips of the magnetic poles 11 and 11, respectively, so that the slits 16d and 17d face each other in the same vertical plane, and are located on the side of the core 10. Part 10
It is arranged along the longitudinal direction of a. That is, the shielding plate 1
4, 15 slits 14d, 15d and shielding plates 16, 17 slit 1
6d and 17d are arranged substantially at right angles to each other.

The magnetic heads 3 and 4 are arranged side by side at a small interval as shown in FIG. 1, and are housed in a casing 2 shown by a two-dot chain line in FIG. Is done.

The respective exciting coils 7, 12 of these magnetic heads 3, 4 are:
As shown in FIG. 5, they are connected in series and connected to the high-frequency excitation power supply circuit 21 of the signal processing circuit 20, and are supplied with the same high-frequency excitation current, that is, the same excitation current having the same voltage and phase. The receiving coils 8 and 13 are differentially coupled to form a differential amplifier circuit.
Connected to 22.

The flat cable (tape card wire) 40 shown in FIG. 4 is the same as the flat cable 40 shown in FIG. 15, and the core conductors 41 to 48 are arranged in parallel at a slight interval.
It is integrally molded with the insulating member 49 to form a belt shape. The core conductors 41 and 42 are thick (wide,
And thick) and set for power supply, and other core conductors 43 ~
Reference numeral 48 is set to be thin (narrow and thin) for signal transmission.

 The operation will be described below.

A high-frequency excitation power supply circuit 26 is connected to the excitation coil 7 of the magnetic head 3.
When a high-frequency excitation current is supplied from the
The high-frequency magnetic flux generated from the bottom surface (end surface) 14 of the shielding plate 14
6C, an eddy current is induced on the bottom surface 14c as shown by a dotted line in FIG. 6A. This high-frequency magnetic flux also interlinks with the bottom surface (end surface) 15c of the shield plate 15 on the other magnetic pole 6 side, and an eddy current is induced on the end surface 15c as shown by a dotted line in FIG. 6 (b). You.

The eddy currents induced in the shielding plates 14 and 15 generate a magnetic flux in a direction that hinders a change in the magnetic flux of the exciting coil 7, and therefore, the magnetic flux passing through the bottom surfaces 14c and 15c of the shielding plates 14 and 15 is weakened. Low magnetic flux density. On the other hand, no eddy current is generated in the slits 14d, 15d of the bottom surfaces 14c, 15c, and therefore, a high magnetic flux density is obtained without obstructing the magnetic flux passing through the slits 14d, 15d. As a result, the shielding plate 14,
As shown in FIG. 7, the magnetic flux distribution in the gap G between the gaps 15 is a non-uniform magnetic flux distribution concentrated in the vertical plane at the positions of the slits 14d and 15d.

In FIG. 7, the horizontal axis represents the distance X from the center of the slit 14d of the shielding plate 14, and the vertical axis represents the magnetic flux density Bm. As a result, the magnetic flux distribution in the gap G between the shielding plates 14 and 15 is extremely narrow and has a high magnetic flux density at the positions of the slits 14d and 15d.

The same magnetic flux distribution as that of the magnetic head 3 can be obtained for the other magnetic head 4. The gradients of the magnetic flux distributions of the magnetic sensors 3 and 4 are substantially perpendicular to each other.

A flat cable 40 as shown in FIG. 3 is inserted into the gap G between the magnetic heads 3 and 4 of the sensor 1, and the sensor 1 is moved at a constant speed as shown by an arrow A to cross the flat cable 40. Let At this time, the slits 14d, 15d of the shielding plates 14, 15 of the magnetic head 3 are
The slits 16d and 17d of the shield plates 16 and 17 of the magnetic head 4 are parallel to the core conductors 41 to 48 (FIG. 8A).
(FIG. 8 (b)).

When the magnetic poles 6, 6 of the magnetic head 3 cross each of the core conductors 41 to 48, an eddy current is induced in the core conductor 31, and the eddy current is maximized at the passage position of the slits 14d, 15d having the maximum magnetic flux density. And becomes smaller as the slits 14d and 15d move away. Therefore, the magnetic flux linked to the receiving coil 8 of the magnetic head 3 changes due to the passing core conductors 41 to 48, and greatly changes at the positions of the slits 14d and 15d. That is, the amount of change of the magnetic flux interlinking with the receiving coil 8 becomes maximum when the slits 14d and 15d of the shielding plate are located immediately above (center) the core conductors 41 to 48. As a result, the induced electromotive force of the receiving coil 8 becomes minimum when the slits 14d and 15d of the shielding plate cross each center of the core conductors 41 to 48.

Since the slits 14d and 15d of the shielding plates 14 and 15 of the magnetic head 3 cross in parallel with the core conductors 41 to 48, the electromotive force induced in the receiving coil 8 is shown in FIG. 9 (a). To change. That is, the electromotive force of the receiving coil 8 is
d and 15d are minimized immediately above each of the core conductors 41 to 48, that is, at the moment when they cross the center, and the change amount is large and extremely steep.

Since each of the slits 16d and 17d of the shield plates 16 and 17 of the magnetic head 4 cross at a substantially right angle with respect to the core conductors 41 to 48, the electromotive force induced in the receiving coil 13 is as shown in FIG. Changes as shown. That is, the electromotive force of the receiving coil 13 is
16d and 17d are substantially constant while traversing each core conductor 31, and the amount of change is small and gentle.

These receiving coils 8 and 13 are differentially coupled,
Therefore, the output voltages cancel each other out, and as a result, the amplitude and frequency of the excitation current become unstable, and the drift and noise level of the output signal due to the influence of the surrounding electromagnetic field are greatly suppressed. Only the signal at each of the center positions is greatly detected. Therefore, by moving the sensor 1 in the direction of arrow A in FIG. 3, it becomes possible to accurately detect the respective center positions of the core conductors 41 to 48 of the flat cable 40.

By the way, when the receiving coils 8 and 13 cross the core conductor, the output voltage changes as shown in FIG. 9 (a) because the core conductors 43 to 48 of the flat cable 40 The conductor is thin, that is, the place where the width is narrow, the core conductor 41,
FIG. 9 (a) shows a case where the width is large, that is, the width is large, such as 42.
Does not simply change as shown in FIG.

That is, as shown in FIGS. 10 (a) to 10 (e), the shielding plate 14,
When the wide core conductor 41 moves parallel to the direction shown by the arrow A in the gap G between 15, the output voltage of the receiving coil 8 changes as shown in FIGS. 11 (a) to 11 (e). . As is clear from this signal waveform, the front end of the core conductor 41 is
The output of the receiving coil 8 at the position where the slits 14d and 15d slightly overlap the slits 14 and 15 increases as shown in FIG. 11 (a), and decreases as it moves as shown in FIG. 10 (b). (FIG. 11 (b)).

The center of the core conductor 41 is the slit 14d, 1 of the shielding plate 14, 15.
At the position coincident with 5d (FIG. 10 (c)), the output of the receiving coil 8 increases again as shown in FIG. 11 (c), and the phase thereof changes to the output shown in FIG. About 180 °. When the core conductor 41 further moves (FIG. 10 (d)), the output of the receiving coil 8 decreases (FIG. 11 (d)), and when the rear end reaches the vicinity of the slits 14d and 15d (FIG. 10 (d)). 10 (e), the output of the receiving coil 8 increases again, and its phase changes by 180 ° (FIG. 11 (e)).

As described above, the output voltages of the receiving coils 8 and 13 are inverted when the core conductor to be detected is thick, that is, when the center conductor coincides with the slits 14d and 15d. If the output voltage is processed as it is as a position signal, the output voltage changes in a complicated manner like the signals e ₁ and e ₂ shown in FIG. Therefore, it is necessary to effectively deal with such a phase change.

In FIG. 5, the signal processing circuit 20 takes in the excitation signal Ex from the high-frequency excitation power supply circuit 21 into the phase shift circuit 23, and makes the phase of the excitation signal Ex as close as possible to the phase of the output signal of the differential amplifier circuit 22. Adjust to This is a differential amplifier circuit
This is because the phase of the output signal waveform 22 changes due to various factors such as the thickness of the shielding plates 14 to 17 and the distance between the cores 5 and 10 of the magnetic heads 3 and 4, and differs from the phase of the excitation signal waveform. .

Comparator 24, an excitation signal Ex which is input from the phase-shifting circuit 23 compares the threshold value V _H which is set in the vicinity of substantially a peak value of the excitation signal Ex, and outputs between signals of Ex> V _H, A sampling pulse signal P is formed. The sampling pulse signal P is formed in synchronization with the cycle of the excitation signal Ex, and its timing is set by the phase shift circuit 23 to near the approximate peak value of the output signal of the differential amplifier circuit 22. By setting the generation timing of the sampling pulse signal P, that is, the sampling timing near the substantially peak value of the output signal of the differential amplifier circuit 22, the detection sensitivity of the sensor 1 can be increased. This sampling pulse signal P is applied to the sample and hold circuit 25.

On the other hand, the signal e output from the differential amplifier circuit 22 is sampled by the sample and hold circuit 25 by the sampling pulse signal P as shown in FIGS. In a state where the core wire conductor 41 does not enter the gap G of the sensor 1, as shown in FIG.
And the output signal e of the receiving coil 8 have the same phase. It should be noted that the portions indicated by dotted lines and diagonal lines in the figure indicate sampling timing by the sampling pulse signal P.

When the core conductor 41 enters the gap G of the sensor 1 and its center coincides with the slits 14d and 15d of the shielding plates 14 and 15, the phase of the output signal e of the receiving coil 8 is excited as shown in FIG. It is sampled in the vicinity of the peak value on the negative side, substantially 180 ° shifted from the phase of the signal Ex. As a result, only the position signal at the center position of the core conductor 41 can be detected.

The position signal output from the sample and hold circuit 25 is
After passing through a low-pass filter 26, it is applied to a low-frequency amplifier circuit 27 and amplified. Position signals e ₁ of core conductor 41 which is outputted from the low frequency amplifying circuit 27, a clean waveform as shown in Figure 14. The core conductor 42 is the same as the core conductor 41. Then, the position signal e ₂ corresponding to the center position of each core conductors 42 to 48 of the flat cable 40 with the movement of the sensor 1
~e ₈ are sequentially output. Each position signal output from the low frequency amplifier circuit 27 is converted into an analog-to-digital
After being converted into a corresponding digital signal by an A / D converter 28, the digital signal is input to a microcomputer 29.

The microcomputer 29 calculates the respective center distances of the respective core conductors 41 to 48 based on the respective position signals of the respective core conductors 41 to 48 of the flat cable 40 sequentially input from the A / D converter 28. The calculation result is printed out by the output device 30 such as a printer. This allows the flat cable 40
It is possible to accurately measure the center distance of each of the core conductors 41 to 48.

Therefore, as shown in FIG. 4, the sensor 1 is alternately scanned in the directions of the arrows A and A 'with respect to the flat cable 40 conveyed in the direction indicated by the arrow B, so that each core conductor 41 of the flat cable 40 is scanned. A center distance of ~ 48 can be measured continuously.

In the present embodiment, two magnetic heads 3 and 4 are used as the sensor 1, each excitation coil is excited identically by the same high-frequency excitation power supply, and each reception coil is differentially coupled. Although the case has been described, the present invention is not limited to this, and the sensor may be configured using only the magnetic head having the higher detection sensitivity, that is, the magnetic head 3. Of course,
When two magnetic heads are used as in the embodiment,
Compared to a sensor using one magnetic head, the amplitude and frequency of the excitation current are unstable, and the drift of the output signal and the noise level due to the influence of the surrounding electromagnetic field can be greatly suppressed. The detection sensitivity of the sensor can be greatly increased.

(Effects of the Invention) As described above, according to the present invention, a non-uniform AC magnetic field is formed by mounting a shielding plate having a slit on each coil of a magnetic head in which an exciting coil and a receiving coil are arranged to face each other. A non-uniform alternating magnetic field is moved across a flat cable in which a number of metal wires are insulated and juxtaposed to detect a change in the output signal of the receiving coil at the center position of each metal wire and to excite the exciting coil. A sampling pulse signal is formed by the excitation current, and the signals sequentially output from the receiving coil at the center position of each metal wire by the sampling pulse signal are sampled and held to sequentially obtain position signals of each metal wire. Since the center distance of each metal wire of the flat cable was measured by the position signal, the metal wire of the flat cable was measured. Even if the thickness (especially the width) is different, it is possible to accurately measure the center distance of each of these metal wires, and furthermore, the computer of the signal processing circuit needs to use complicated signal calculation software. There is an excellent effect that the calculation can be performed by simple calculation software.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a magnetic head of a sensor applied to the method for measuring the distance between metal wires according to the present invention, FIG. 2 is an assembled perspective view of a shielding plate of FIG. 1, and FIG. FIG. 4 is a sectional view of the magnetic head of FIG. 1, FIG. 4 is an explanatory view showing the relationship between the main part of the sensor of FIG. 3 and a flat cable, and FIG. 5 is a signal processing circuit applied to the measuring method according to the present invention. FIG. 6 is a circuit diagram showing one embodiment, FIG. 6 is a diagram showing an eddy current induced on the bottom surface of the shield plate of the magnetic head of FIG. 1, and FIG. 7 is a diagram showing a gap between shield plates of the magnetic head of FIG. FIG. 8 is a diagram showing the magnetic flux distribution, FIG. 8 is a diagram showing the relationship between the magnetic head and the core conductor in FIG. 3, FIG. 9 is a diagram showing the electromotive force of the receiving coil of the magnetic head in FIG. 3, and FIG. FIG. 3 is an explanatory view of a case where a wide core conductor moves between gaps of the magnetic head of FIG. 3, and FIG. 11 is a view at each position of the core conductor of FIG. 12 is a waveform diagram showing the output voltage of the receiving coil, and FIG. 12 is a waveform diagram showing the relationship between the excitation signal and the output signal of the differential amplifier circuit when there is no core conductor between the shield plates of the magnetic head of FIG. FIG. 13 is a waveform diagram showing the relationship between the excitation signal and the output signal of the differential amplifier circuit in a state where the center of the core conductor is aligned with each slit between the shield plates of the magnetic head of FIG. 3, and FIG. Is a signal waveform diagram showing the center position of each core conductor of the flat cable shown in FIG. 4 detected by the signal processing circuit of FIG. 15, FIG. 15 is a cross-sectional view showing an example of the flat cable, and FIG. FIG. 6 is a signal waveform diagram showing a center position of each core conductor of the flat cable according to the measuring method of FIG. 1 ... sensor 2 ... casing 3, 4 ... magnetic head, 5, 10 ... core, 6, 11 ... magnetic pole, 7, 12 ... exciting coil, 8, 13 ... receiving coil, 14 ~ 17 ... Shield plate, 14
d to 17d: slit, 19: edge sensor, 20: signal processing circuit, 40: flat cable, 41 to 48: core conductor (metal wire), 49: insulating member.

Claims (3)

(57) [Claims] 1. A non-uniform AC magnetic field is formed by attaching a shield plate having a slit to each coil of a magnetic head in which an exciting coil and a receiving coil are arranged to face each other. Move across the flat cable insulated and juxtaposed, detect the change of the output signal of the receiving coil at the center position of each metal wire, and form a sampling pulse signal by AC exciting current exciting the exciting coil, According to the sampling pulse signal, the signal sequentially output from the receiving coil at the center position of each metal wire is sampled and held to sequentially obtain position signals of each metal wire. A method for measuring the distance between metal lines, comprising measuring a center distance of the metal wires. 2. The method according to claim 1, wherein the sampling pulse signal is formed in synchronization with the exciting current. 3. The method according to claim 1, wherein said sampling pulse signal is formed near a substantially peak value of an output signal of said receiving coil.