JPS6178571A - Welding arc monitoring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a monitoring device for a welding arc, and particularly to a monitoring device that can clearly image the peripheral area of a welding arc without causing halation. .

[Prior art 1] Generally, in automatic welding, etc., a device for monitoring the welding arc is an optical television camera that takes m-images of the welding arc, and a device that projects an image of the arc based on the video signal from this television camera. Surveillance V & Snow consisting of a monitor receiver made in the art is already known.

By the way, in order to perform welding operations accurately, it is necessary to obtain a clear image that clearly distinguishes the welding arc from the surrounding area. When an extremely high arc area is detected, due to the nature of the TV camera, significant halation 2 occurs in the image centered around the arc area 1, as shown in Figure 2, and peripheral areas such as the electrode 3 and molten pool 4 are clearly recognized. I can't.

Therefore, in order to suppress this halation phenomenon, a neutral density filter is provided in front of the television camera to reduce the incident light a as a whole.

[Problems to be Solved by the Invention] By the way, as described above, when the brightness of the entire image is reduced using a neutral density filter, the peripheral area is excessively reduced,
There was a problem in that only the arc part was reflected when it was towed, and the peripheral part could not be covered.

Therefore, it is also possible to use a partial neutral density filter in which a neutral density filter is formed only in the part corresponding to the arc part, but this allows the positional relationship between the arc part and the partial neutral density filter to be adjusted even slightly. If it deviates, it will not be possible to exhibit a sufficient light attenuation effect, so there is a problem in that it cannot be applied to moving images, although this does not pose a problem when capturing fixed images.

[Object of the Invention] The present invention has focused on the above-mentioned problems and has been devised to effectively solve the problems.

An object of the present invention is to provide a monitoring device that can clearly image the surrounding area of a welding arc part without reducing the brightness of only this arc part and causing halation even though the welding arc part moves. It is in.

[Summary of the Invention] The configuration of the present invention that achieves the above object uses a transmissive liquid crystal dot matrix as a neutral density filter, and
The XY! The main idea is that by controlling the voltage of the target, a filter was created on the liquid crystal dot matrix that matched the shape of the bright arc part, and the brightness of only the arc part was attenuated to balance the brightness with the surrounding area. do.

[Embodiment] A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a monitoring device according to the present invention,
FIG. 3 is a plan view showing the liquid crystal dot matrix, and FIG. 4 is a block diagram showing the matrix control circuit.

Illustration! Reference numeral 5 is a normal optical television camera that takes an m-image of the welding arc portion 6.
- A monitor receiver 8 is connected via the pull 7 and displays an image of the arc portion 6 based on the Ili image signal from the television camera 5. A liquid crystal dot matrix 9 that partially acts as a neutral density filter is provided between the arc portion 6 and the television camera 5 as described later, and this dot matrix 9 partially reduces the transmittance of light. A known matrix 1ilJ11] circuit 10 is electrically connected via wiring 11. The liquid crystal dot matrix 9 is integrally attached and fixed to the television camera side by a support member (not shown).

This liquid crystal dot matrix 9 is a transmissive unit liquid crystal plate 1 whose light transmittance is changed by controlling the supply of pulse voltage.
For example, the third
As shown in the figure, <1!1 (Y axis), horizontal (X axis) each 10
A total of 10,000 unit liquid crystal plates 12 are arranged, each having 0 unit liquid crystal plates 12, and an arbitrary blackened pattern 13 can be removed by controlling pulse voltages applied to each of the X-axis and Y-axis. A control signal for controlling this blackening pattern is output from the matrix control circuit 10. This control circuit 10 is a circuit that reduces the amount of light transmitted through the corresponding unit liquid crystal plate of the liquid crystal dot matrix 9 in response to the pixel imaging @brightness obtained from the television camera exceeding a predetermined value. To explain in detail based on FIG. 4, this control circuit 1Q includes a separating circuit 14 that separates a composite synchronizing signal a obtained from a television camera 5 into a video signal and a synchronizing signal C, and all video signals obtained from this. Synchronization is performed by a binarization circuit 15 that performs threshold processing on the captured WA luminance of each pixel using a predetermined value and binarizes the processed image into 0 or 1, and a horizontal synchronization signal d obtained from the separation circuit 14. an X-axis pulse generation circuit 16 which outputs an X-axis pulse signal e to the liquid crystal dot matrix 9 based on the output value from the 21a conversion circuit 15, and a vertical +11 signal from the 5F female 1 circuit 14. It mainly consists of a Y-axis pulse generation circuit 17 that synchronizes and outputs a Y-axis pulse signal @9 to the liquid crystal dot 7 matrix 9.The luminance threshold set in the 21i conversion circuit 15 is as follows. TV camera 5
It is preferable to set the luminance to a limit such that the l#l picture tube built in the camera cannot recognize differences in luminance.

Next, the operation of the present invention configured as described above will be explained.

First, the arc light generated at the welding arc section 6 passes through the liquid crystal dot matrix 9 and then enters the optical television camera 5 where it is imaged, and the video signal is sent to the monitor receiver 8 via the cable 7. The information is transmitted and an image of the welding arc is projected here. Here, if the liquid crystal dot matrix 9 is not illuminated in any way, the brightness of the arc portion 6 is too strong, resulting in an image with halation centered on the arc portion, making it impossible to clearly see the peripheral portion. According to the present invention, the composite signal a obtained by the television camera 5 is guided to the matrix control circuit 1o, and the intensity of the video signal obtained by the separation port 2814 built in this is set to a predetermined value. Threshold processing and binarization processing are performed, and based on this output, an X-axis pulse signal e is output from the X-axis pulse generation circuit 16 to the liquid crystal dot matrix 9 to operate the unit liquid crystal plates 12... There is. Therefore, a blackened pattern 13 having a similar shape to the welding arc portion 6 whose luminance is higher than a predetermined value is obtained in the liquid crystal dot matrix 9.
As a result, the amount of transmitted light is reduced in the blackened pattern 13, so the amount of light entering the television camera 5 at the arc portion is suppressed, and the amount of light is balanced with the surrounding area, resulting in a good image without halation as described above. You can get the image. Here, since the amount of transmitted light of the blackened pattern 13 corresponding to the arc portion decreases, the blackened pattern 13 instantly disappears when the brightness of the transmitted light passing through it becomes less than the threshold value in the matrix control circuit 10. However, at the same time, the brightness of the arc that enters the television camera 5 increases again and exceeds the threshold value, and a blackening pattern is formed again as described above, reducing the amount of light incident on the camera by -+1. . In this way, the generation and disappearance of the blackening pattern is repeated at high speed in accordance with the scanning time of the X-axis or Y-axis, so that the light l of the arc portion captured by the television camera 5 is reduced as a whole. Good images as described above can be obtained.

Further, even if the welding arc portion 6 or the television camera 511 moves and the arc portion visible through the liquid crystal dot matrix 9 moves, the blackening pattern 13 also moves due to the operation of the matrix M 10 circuit 10 described above. Correspondingly, the blackened pattern 13a moves as shown by the broken line in FIG.
is formed, so even when converting moving images into images, good images can always be obtained.

[Effects of the Invention] As described above, according to the present invention, a transparent liquid crystal dot matrix is provided in front of a television camera, and
rlJ! For IO, a matrix i+11 circuit is provided that generates a pulse voltage based on the brightness received from a television camera, and a blackened pattern with low transmittance is created on the liquid crystal dot matrix to correspond to the shape of the arc with high brightness. Since only the arc portion is dimmed, halation of the arc portion can be eliminated and a clear image can be obtained. Therefore, since the arc portion and its surroundings can be clearly recognized, remote control of the welding operation can be performed accurately, and the occurrence of welding defects can be prevented. Furthermore, even if the arc portion moves on the liquid crystal dot matrix, the blackening pattern will also move accordingly, making it possible to obtain clear images not only for still images but also for moving images.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing a monitoring device according to the present invention, and FIG.
3 is a plan view showing a liquid crystal dot matrix in which a blackened pattern appears, and FIG. 4 is a block diagram showing a matrix control circuit.

Claims (1)

[Claims] A welding arc monitoring device comprising an optical television camera that images the welding arc, and a monitor image receiver that displays an image of the arc based on a signal from the television camera, which includes the arc and the television. A liquid crystal dot matrix is provided between the television camera and the television camera, and the imaging brightness obtained from the television camera is equal to or higher than a predetermined value. A monitoring device for a welding arc portion, comprising: a matrix control circuit that responds to this by reducing the amount of light transmitted through the corresponding unit liquid crystal plate of the liquid crystal dot matrix.