JPH04372879A - Inspection of disconnection of hot wire in frosted glass for car - Google Patents

Abstract

PURPOSE:To simply the presence of the disconnection of the hot wires in frosted glass for a car provided with an anti-fogging heater formed by parallelly connecting a plurality of the hot wires at every hot wires in a non-contact state. CONSTITUTION:A probe 34 for connecting a power supply is brought into contact with the connection part 16 with a power supply of an anti-fogging heater 12 to supply commercial AC current to the anti-fogging heater 12. A magnetic field detection head 18 is moved so as to cross respective hot wires 14 connected in parallel to detect the magnetic fields generated from the respective hot wires 14 to inspect the presence of the disconnection of the hot wires 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting hot wire breakage in anti-fog glass for automobiles.

0002

2. Description of the Related Art Generally, the rear glass of an automobile is made of anti-fog glass, and a plurality of hot wires connected in parallel are printed on the surface of the glass. Check if the anti-fog heater is disconnected.
If there is an obvious abnormality, it can be visually determined, and if it cannot be visually determined, it can be detected by energizing the heater and measuring the resistance value.

[0003] Specifically, this anti-fog heater has two connecting parts at its ends for connection to the electrical wiring inside the vehicle.
Therefore, for example, by connecting the heater to a power source at the connection point, energizing it, and measuring the resistance value of the heater at that time, it is possible to know whether or not each hot wire is disconnected.

0004

[Problems to be Solved by the Invention] However, in the case of such a method based on resistance value measurement, not only high measurement accuracy is required, but also the need to check the accuracy of multiple hot wires connected in parallel even if it is found that there is a disconnection. There is a problem in that it is not possible to identify which of the hot wires is broken.

Although it is possible to identify a broken hot wire by measuring the resistance value of each of a plurality of hot wires, such a process is extremely complicated and difficult to perform on an actual production line. .

[0006]

[Means for Solving the Problems] The method of the present invention has been devised to solve these problems, and its gist is to provide an anti-fog heater formed by connecting a plurality of hot wires in parallel. A method of inspecting whether or not there is a disconnection of the hot wire in the installed anti-fog glass for an automobile, the method comprises: contacting a connecting body from the power source side to the connection part with the power source of the anti-fog heater; The purpose of the present invention is to inspect whether or not each hot wire is disconnected by moving a magnetic field detection head across the hot wires connected in parallel and detecting the magnetic field generated by each hot wire while applying a commercial alternating current. .

[Operations and Effects of the Invention] As described above, in the present invention, a connecting body from the power supply side is brought into contact with the connection part of the anti-fog heater to the power supply, and a commercial alternating current is applied to the anti-fog heater. . When a commercial alternating current is applied to the anti-fog heater, a magnetic field is generated by electromagnetic induction in each of the parallel-connected hot wires.

By running a magnetic field detection head across the plurality of hot wires and detecting the magnetic field of each hot wire, it is possible to determine whether or not each hot wire is broken.

If there is a break in any one of the plurality of hot wires, no alternating current will flow in that hot wire, and therefore no magnetic field will be generated around the hot wire, so the magnetic field detection head detects the wire breakage. It is possible to determine the presence or absence of

The magnetic field detection head can be configured to include, for example, a special coil. When this magnetic field detection head is passed through a magnetic field generated around a hot wire, a current induced by the magnetic field flows through the coil of the detection head, and the strength of the current increases in proportion to the strength of the magnetic field. By measuring the current, the magnitude of the magnetic field can be determined.

[0011] In the present invention, the power source is 50Hz to 60Hz.
A commercial power source of Hz is used, which has the advantage that the inspection device can be constructed at low cost.

[0012] Furthermore, in the present invention, since the magnetic field is detected for each hot wire to determine the presence or absence of a wire breakage, in the event of a wire breakage, it is possible to immediately know which hot wire is broken. Tests can be performed without contact, so
This has the advantage that there is no risk of damaging the heat rays during inspection.

[0013] Inspection items for the anti-fog heater include a test in which a current of about the rated current is passed through the anti-fog heater. A current of this magnitude will flow. Therefore, according to the present invention, this test can be performed simultaneously when inspecting for wire breakage.

In the present invention, in order to flow an alternating current to the anti-fog heater, connecting bodies from the power supply side are brought into contact with the connection parts with the power supply at both ends of the anti-fog heater. Since it is formed with a wide area for connection with the in-vehicle electrical wiring, the connection body from the power source side can be brought into contact with these connection parts without strict positioning. Therefore, when automating the inspection for the presence or absence of breakage of the hot wire, there is an advantage that the positioning device is simple.

[0015]

Embodiments Next, embodiments of the present invention will be described in detail with reference to the drawings. In Fig. 1, 10 is an automobile rear glass (
(anti-fog glass), and an anti-fog heater 12 is provided on the glass surface.

As shown in FIG. 2, this anti-fogging heater 12 has a plurality of narrow heating wires 14 of about 1 to 2 mm connected in parallel printed on the glass surface, and has a power supply connected to both ends. A connection part 16 is formed to connect with the vehicle, that is, to connect with the in-vehicle electrical wiring. This connection part 16 is 1cm x 2c
It has a large area of about 2.0 m.

In FIG. 1, reference numeral 18 denotes a magnetic field detection head having a coil inside, which detects the presence or absence and strength of a magnetic field as a current value. The current extracted here is amplified by a preamplifier 20 and a main amplifier 22, converted into a digital signal by an A/D converter 24, and then sent to a computer 26, where it is processed. The results are displayed on the display 28, outputted on paper by the printer 30, and further recorded in the recording means 32.

In the method of this example, the power supply connection probe 34 is brought into contact with the connection part 16 of the anti-fog heater 12, and the anti-fog heater 1
Pass commercial alternating current through 2. As a result, a magnetic field is generated around each heating wire 14 of the anti-fog heater 12.

Meanwhile, at the same time, the magnetic field detection head 18 is made to run across each heating wire 14 of the anti-fog heater 12. If the hot wire 14 is not broken, when the magnetic field detection head 18 crosses it, an alternating current is generated in the coil of the magnetic field detection head 18 due to electromagnetic induction due to the alternating magnetic field generated around the hot wire 14 at that time. is induced. The current is input to a computer 26 via a preamplifier 20, a main amplifier 22, and an A/D converter 24.

As described above, by passing the magnetic field detection head 18 through each hot wire 14 of the anti-fog heater 12, each hot wire 14
The presence and strength of the magnetic field can be measured at each time.

FIGS. 3 and 4 show this situation. In FIG. 3, the horizontal axis represents the amount of movement of the magnetic field detection head, and the vertical axis represents the strength of the magnetic field. Each wave 36 representing the strength of the magnetic field is actually obtained by half-wave rectifying the alternating current taken out by the detection head 18 and then averaging it by a capacitor.

As is clear from FIGS. 3 and 4, when the magnetic field detection head 18 is run so as to pass the hot wire 14, no wave 36 representing the generation of a magnetic field is generated at the location of the broken hot wire 14. . Therefore, by observing the waves 36 that appear when the magnetic field detection head 18 runs, and by performing appropriate processing, it is possible to immediately determine whether or not the hot wire 14 is broken, the number of breaks, and the identification of the broken hot wire 14. can.

[0023] Although the embodiments of the present invention have been described in detail above, this is merely an example, and the present invention does not differ from the gist of the invention, for example, by detecting a magnetic field by a method different from the above example. The present invention can be implemented with various modifications based on the knowledge of those skilled in the art without departing from the scope.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a hot wire disconnection inspection method according to an embodiment of the present invention.

FIG. 2 is a plan configuration diagram of the anti-fog heater in FIG. 1;

FIG. 3 is a diagram showing the state of magnetic field generation for each hot wire.

FIG. 4 is a diagram illustrating the principle of the method shown in FIG. 1;

[Explanation of symbols]

10 Rear glass 12. Anti-fog heater 14 Heat ray 18 Magnetic field detection head

Claims (1)

[Claims] 1. A method for inspecting the presence or absence of disconnection of a hot wire in an anti-fog glass for an automobile equipped with an anti-fog heater formed by connecting a plurality of hot wires in parallel, the method comprising: a power source for the anti-fog heater; A connecting body from the power supply side is brought into contact with the connecting part of the heater, and a commercial alternating current is applied to the heater, while a magnetic field detection head is moved across each of the parallel-connected hot wires to detect the electric field generated by each hot wire. 1. A method for inspecting breakage of hot wires in anti-fog glass for automobiles, the method comprising inspecting the presence or absence of breakage of each hot wire by detecting a magnetic field.