JP4161145B2 - Luminescent imaging device using CCD camera and laser illumination - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging device for a luminous body using a CCD camera and laser illumination for imaging a luminous body that emits intense light such as welding with a significantly darker background.
[0002]
[Prior art]
When a light emitting body that emits strong light such as welding is imaged with a CCD camera, halation occurs and only a lighted image of the light emitting portion can be obtained. In order to observe the welded state, not only the brightly shining molten metal and high-temperature gas parts, but also the background of the welding rod, welding torch, solidified weld metal, base metal, etc. are displayed on one screen together with the light emitting part. Is required.
[0003]
There is a composite image method as a method for projecting such extremely bright and dark objects on the same screen. The CCD has the function of an electronic shutter by adjusting the charge accumulation time, and the shutter time can be adjusted. The high-speed shutter does not show dark parts, but bright parts appear clear. With the low-speed shutter, the bright part is saturated and flies, but the dark part appears clear. Only a good point can be cut out from these two images to create a composite image. FIG. 3 is a diagram for explaining this principle, in which A indicates a bright image and B indicates a dark image. (A) is taken with a high-speed shutter, B is darkly crushed, and A is clearly visible. (B) is an image taken with a low-speed shutter. A is saturated and flies, but B appears clearly. (C) is an image obtained by extracting and combining the optimum images of the two.
[0004]
In addition, there is a method in which a high-illuminance pulse laser is used as a light source, and a illuminant and a background are imaged simultaneously by irradiating a dark background. In this case, the pulse laser is irradiated in synchronization with the charge accumulation period of the CCD. FIG. 4 is a diagram showing this state. In this case, if the charge accumulation time is that of a normal CCD, the image of the illuminant is too bright with respect to the background image by the pulse laser, and neither the background nor the image of the illuminant can be obtained. For this reason, an electric shutter is used to shorten the charge accumulation time. FIG. 5 shows a case where the amount of light received is reduced by an electronic shutter so that the amount of light reflected by the pulse laser is substantially equal. In this way, a clear image of the light emitter and the background can be obtained on the same screen. When the high-speed shutter is used as described above, it is necessary to accurately synchronize the CCD frame period and the pulse laser period.
[0005]
[Problems to be solved by the invention]
The method for synthesizing the screen described above is complicated and time consuming, and the apparatus is expensive. In the method using a pulse laser, a high-accuracy clock device is used for the pulse laser generator in order to synchronize the pulse period and the CCD frame period, and the apparatus is expensive.
[0006]
The present invention has been made to solve such problems. That is, an object of the present invention is to provide a light emitting body imaging device using a CCD camera and laser illumination in which the period of the pulse laser is synchronized with the CCD frame period by a simple device.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a CCD camera that images a light emitter, a frame signal extraction unit that extracts a frame signal of the CCD camera, a delay circuit that delays the extracted frame signal, A pulse laser generator that generates a pulse laser at a delayed cycle of the delay signal, and a laser irradiation unit that irradiates the pulse laser generated by the pulse laser generator near the light emitter,
The delay circuit synchronizes the frame period of the CCD camera and the pulse laser period by delaying the frame signal.
[0008]
After taking out the frame signal of the CCD camera and delaying this frame signal by an integral multiple of the frame period, a pulse laser is generated at the delayed signal period to irradiate the periphery of the light emitter. Since the period is the same as the CCD frame period even when the delay is an integral multiple, the pulse laser period always matches the CCD frame period. As shown in FIG. 5, the CCD charge accumulation time is shortened with a high-speed shutter, and by balancing the amount of light received from the reflected light of the pulse laser and the amount of light received from the light emitter, the light emitter and the background are clearly reflected. An image can be obtained.
[0009]
According to a second aspect of the present invention, there is provided a period expander for increasing the period of the extracted frame signal by an integral multiple , and the expansion period is input to the delay circuit, and the delay circuit is input from the period expander. Further, by delaying the frame signal, the frame period and the pulse laser period are synchronized.
In the invention of claim 3, comprising a memory for storing an image of one cycle before the pulsed laser is irradiated in the vicinity of the light emitter, the image includes the light emitter, and the integer multiple is an integer multiple of 2 or more, When the pulse laser is not irradiated in the vicinity of the light emitter, the image is displayed.
[0010]
When the integer is 1, a pulse laser is emitted for each frame, and a clear image of the light emitter and the background is obtained. When the integer is N greater than 1, a pulse laser is emitted every N frames. In this way, an image in which the illuminant and the background are shown simultaneously can be obtained. In this way, the cycle of the pulse laser can be lengthened, so that the pulse laser generator is simplified and the cost is reduced.
According to a fourth aspect of the present invention, the light emitter is a welded portion.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an imaging device for a light emitter using a CCD camera and laser illumination according to an embodiment. The light emitter 1 is an arc or plasma generated by welding, and the background is a torch 1a, a welding rod 1b, a weld metal 1c, a base material 1d, and the like. The CCD camera 2 is arranged so as to project the background around the light emitter 1, and the frame signal extraction unit 3 extracts a frame signal from the video signal of the CCD camera 2. The video signal from the CCD camera 2 is recorded on the video deck 4a and displayed on the monitor 4b.
[0012]
The 1 / n decounter 5 is a device that increases the period by dividing the frequency of the frame signal by an integer. The frame period of the CCD camera 2 is 30 Hz (exactly 29.97 Hz) as with the television signal. Normally, 30 Hz, 15 Hz, and 10 Hz of n = 1, 2, 3 are used, and can be switched to one by a switch. The delay circuit 6 outputs a signal having a period delayed by n (n is an integer, usually n = 1) from the period output from the 1 / n decounter 5. As a result, a delay period of less than one period can be eliminated, and the frame period and the pulse laser period can be reliably synchronized. For example, in the case of an Nd-YAG laser, the pulse laser generator 7 discharges the flash lamp in a pulsed manner and excites it to oscillate. By performing the period of this exciting pulse with the signal of the delay circuit 6, it is possible to output pulse lasers of 30 Hz, 15 Hz, and 10 Hz. The laser irradiation unit 8 is a device that irradiates the illuminant 1 and the background by diffusing the pulse laser generated by the pulse laser generator 7, and diffusing and irradiating the pulse laser by providing a ball lens or the like at the tip.
[0013]
FIG. 2 is a diagram showing the synchronization between the frame period of the CCD camera 2 and the period of the pulse laser. A shows a case where the CCD frame period during normal charge accumulation where the electronic shutter does not act is 30 Hz. B is a case where the charge accumulation time is significantly reduced at the time of high-speed shutter, and the luminous body 1 such as a welded part is imaged, and the period is 30 Hz without change. C indicates a period in which the pulse laser is generated in synchronization with 30 Hz. D shows the case where the pulse laser is generated at 15 Hz and synchronized with the frame signal, and E shows the case where the pulse laser is generated at 10 Hz and synchronized with the frame signal. If the frequency is lowered like D and E, the pulse laser generator 7 is simplified and the cost is reduced. However, on the screen not irradiated with the laser, only the light emitter 1 exists, the screen flickers, and the sharpness decreases. In this case, a clear image without flickering can be obtained by storing the image one cycle before irradiation with the pulse laser in a memory and displaying the stored image at a period when the pulse laser is not irradiated. In addition, since the image one cycle before is always used, the change in the light-emitting body 1 can be substantially followed, so that the utility value is great.
[0014]
【The invention's effect】
As described above, according to the present invention, the pulse period is generated using the frame period of the CCD camera, so that the frame period of the CCD camera and the pulse laser can be synchronized with a simple system. Further, the pulse laser generator can be made inexpensive by setting the cycle of the pulse laser to 1 / integer of the frame cycle.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.
FIG. 2 is a diagram illustrating frequency synchronization according to the embodiment.
FIG. 3 is an explanatory diagram of a conventional composite image method.
FIG. 4 is a diagram for explaining a normal CCD charge accumulation time;
FIG. 5 is a diagram showing the synchronization between a CCD using a high-speed electronic shutter and a pulse laser.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light emitter 1a Torch 1b Welding rod 1c Welding metal 1d Base material 2 CCD camera 3 Frame signal extraction part 4a Video deck 4b Monitor 5 1 / n Decounter 6 Delay circuit 7 Pulse laser generator 8 Laser irradiation part

Claims (4)

CCD camera for imaging the illuminant, frame signal extraction unit for extracting the frame signal of the CCD camera, a delay circuit for delaying the extracted frame signal, and a pulse laser for generating a pulse laser at the period of the delayed delay signal A generator, and a laser irradiation unit for irradiating the vicinity of the light emitter with the pulse laser generated by the pulse laser generator,
The delay circuit synchronizes a frame period and a pulse laser period of the CCD camera by delaying the frame signal, and an imaging device for a light emitter using a CCD camera and laser illumination. A period expander is provided to increase the period of the extracted frame signal by an integral multiple , and the expansion period is input to the delay circuit,
2. The CCD camera and laser according to claim 1, wherein the delay circuit synchronizes the frame period and the pulse laser period by delaying the frame signal input from the period expander. 3. An imaging device for a illuminant using illumination.   A memory for storing an image of one cycle before the pulsed laser is irradiated in the vicinity of the light emitter, the image including the light emitter, and the integer multiple is an integer multiple of 2;
  The imaging device for a light emitter using a CCD camera and laser illumination according to claim 2, wherein the image is displayed when a pulse laser is not irradiated in the vicinity of the light emitter. . The said light-emitting body is a welding part, The imaging device of the light-emitting body using the CCD camera and laser illumination as described in any one of Claims 1-3 characterized by the above-mentioned.

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