JP3604883B2 - Quartz tube bubble detector - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bubble detecting device for a quartz tube, and more particularly to a bubble detecting device for a quartz tube using an imaging unit.
[0002]
[Prior art]
In general, quartz glass is a single component of SiO ₂ , has excellent heat resistance, is chemically stable, has excellent light transmission, and has excellent electrical insulation. For this reason, a quartz tube made of quartz glass is used as a light source for illumination or a semiconductor manufacturing process member.
[0003]
When this quartz tube is used as a light source for lighting or a semiconductor manufacturing process member, the presence of bubbles such as hydrogen gas introduced in the manufacturing process in the quartz tube not only reduces the strength of the quartz tube but also reduces the intensity of the quartz tube. There is a possibility that the product characteristics of the light source or the semiconductor manufacturing process member may be impaired, or the use atmosphere may be adversely affected.
[0004]
Therefore, it is necessary to thoroughly inspect the bubbles present in the quartz tube during the manufacture of the quartz tube, and to provide a quartz tube free of bubbles.
[0005]
Generally, a quartz tube is used to put raw material quartz powder into a quartz melting furnace and heat it with a heater in a hydrogen atmosphere to make the fused quartz melt into a narrow portion provided at the lower part of the melting furnace and the inside of the quartz tube as a cavity. It is molded and manufactured through a narrow annular gap formed by a mandrel which is a heat-resistant guide.
[0006]
Since the quartz tube is manufactured in a melting furnace in a hydrogen atmosphere, the formed quartz tube may mainly contain large and small bubbles of hydrogen. Occasionally, an operator patrols as needed to visually check the quartz tube.
[0007]
However, in this visual inspection, accuracy is low, and when the width of the bubble is 0.2 mm to 0.3 mm or more, there are obstacles such as reducing the characteristics of the product using the quartz tube or reducing the strength of the quartz tube. Although such a quartz tube should be excluded as a defective product, it is often overlooked and may be sent to the next process.
[0008]
Also, in the visual inspection, the operator approaches the high-temperature melting furnace where the temperature in the melting furnace at the time of melting the quartz is as high as about 2300 ° C., and visually observes the formed high-temperature quartz tube of about 1000 ° C. It is a very dangerous task. This visual inspection also hinders automation of the quartz tube manufacturing process.
[0009]
Therefore, there has been a demand for a quartz tube bubble inspection apparatus which can eliminate the oversight of bubbles, can perform an unmanned bubble inspection, and can automatically perform online bubble inspection.
[0010]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above-described circumstances, and a bubble inspection device using a quartz tube using an imaging unit makes the bubble inspection unmanned. Further, the bubble inspection of the quartz tube can be performed online by automation. An object of the present invention is to provide a bubble detector for a quartz tube.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is provided to face a quartz tube that is continuously extruded or drawn out of a quartz melting furnace in a tubular shape, and images a state of bubbles existing in the quartz tube. An image processing device that receives an image signal of a bubble state from the image pickup device, analyzes the image signal and measures the bubble state, and an output device that outputs processing information of the image processing device. A quartz tube bubble detecting device, wherein three of said image pickup means are provided on the same side with respect to an extension of the diameter of said quartz tube, and two of said three image pickup means are provided with a reflection mirror. In summary, the present invention provides a bubble detecting device for a quartz tube, characterized in that the outer peripheral position of the quartz tube can be imaged from the outside at substantially equal intervals in the circumferential direction by the three imaging means. .
[0013]
The invention according to claim 2 of the present application is characterized in that the imaging means provided at the center of the three imaging means and the two reflecting mirrors are provided at an interval of approximately 120 degrees on the outer peripheral side of the quartz tube. is summarized in that a bubble detector of the quartz tube of claim 1, wherein.
[0014]
The invention of claim 3 of the present application is directed to an image pickup means provided to face a quartz tube continuously extruded or drawn out of a quartz melting furnace in a tubular manner, and an image pickup device for picking up an image of a bubble present in the quartz tube. What is claimed is: 1. A bubble detector for a quartz tube, comprising: an image processing device that receives an image signal of a bubble state, analyzes the image signal and measures the bubble state, and an output device that outputs processing information of the image processing device. a first imaging means and the second iMAGING means disposed at intervals of approximately 90 degrees around the quartz tube to image the state of the foam facing surface of the quartz tube, respectively, the two image pickup means and is disposed on the opposite side with respect to the quartz tube copy the state of the rear surface of the bubbles approximately corresponds to the quartz tube on the opposite surface of the quartz tube, the first reflecting mirror and the second in the first imaging means and an optical system the second reflection mirror in the imaging means and an optical system A, extension of the first imaging means is disposed with a quartz tube with a predetermined distance, the second reflection mirror has a constant distance between the center of the quartz tube, and the diameter disposed in a predetermined angular rotation position from the orthogonal plane of the line, by imaging the opposed surface and the first reflecting mirror and second reflecting mirrors of the quartz tube by the first imaging means and second imaging means In addition, the gist of the present invention is to provide a bubble detector for a quartz tube, characterized in that the state of bubbles on the opposed surface and the back surface of the quartz tube is imaged.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a bubble detector for a quartz tube according to the present invention will be described with reference to the accompanying drawings.
[0020]
FIG. 1 shows an embodiment in which a quartz tube bubble detecting apparatus 1 according to the present invention is implemented, and FIG. 2 is a schematic view showing a main part thereof, which is manufactured by a continuous pipe drawing method using a melting furnace 2. This is for inspecting bubbles existing in the quartz tube 3. The melting furnace 2 is made of a heat-resistant metal crucible 5 to which the raw material powder M of quartz is supplied and heated by the heater 4, a heat-insulating refractory 6 surrounding the crucible 5 and the heater 4, and a metal crucible surrounding the refractory 6. Is formed from the outer periphery 7 of the first embodiment. Further, a mandrel 8 made of metal and having a disk-shaped projection 8a is inserted into the crucible 5 from above the crucible 5 to the bottom, and the fused quartz is formed by the projection 8a and the mold 9 provided on the bottom of the crucible 5. Mm is extruded to form an annular gap 10 forming the quartz tube 3.
[0021]
Further, at least three CCD line sensors 11a, 11b, 11c constituting an image pickup means, for example, an optical inspection means, are disposed facing the quartz tube 3, and each of the CCD line sensors 11a, 11b, 11c is connected to the image processing device 12. It is electrically connected. Further, the image processing device 12 is an output device for outputting the processing information, for example, a control device 14 for controlling an electric input supplied to the monitor 13 and the heater 4, or an automatic device for automatically sorting non-defective products and non-defective products in the next process. It is electrically connected to a sorter control unit 15 of a sorter (not shown).
[0022]
The three CCD line sensors 11a, 11b, and 11c can capture an image of the outer peripheral surface of the quartz tube 3 almost uniformly. When the three CCD line sensors 11a, 11b, and 11c divide the measurement area into two on the extension line L of the diameter of the quartz tube 3, all three CCD line sensors are arranged intensively on one side of the measurement area, and the imaging location (measurement area) ) To save space.
[0023]
The three CCD line sensors 11a, 11b, and 11c are configured so that the outer peripheral surface of the quartz tube 3 can be imaged from the outside at equal intervals in the circumferential direction and inspected. Specifically, a reference CCD line sensor 11a is provided on a radiation ray Sa in the radial direction (diameter direction) of the quartz tube 3 orthogonal to the extension line L of the diameter of the quartz tube 3 obtained by dividing the measurement region into two. Two reflecting mirrors 16b and 16c are disposed on the outer peripheral side of the quartz tube 3 rotated by 120 degrees at the central angle around the axis of the quartz tube 3 from the reference CCD line sensor 11a. The reflected light passes through the outer peripheral side of the quartz tube 3 and is reflected by the remaining two CCD line sensors 11b and 11c.
[0024]
Thus, one of the three CCD line sensors 11a, 11b, and 11c is provided so as to face the outer peripheral position of the quartz tube 3 so that the reference position of the quartz tube 3 can be imaged. The two CCD line sensors 11b and 11c are installed so as to be able to image a position different from the reference position of the quartz tube 3 by 120 degrees from the reference position by the reflection mirrors 16b and 16c.
[0025]
Note that four or more CCD line sensors may be provided so that the outer peripheral surface of the quartz tube can be imaged at substantially equal intervals.
[0026]
Since the quartz tube bubble detecting device according to the present invention has the above structure, in order to manufacture the quartz tube 3 by the continuous drawing method, the raw material powder M is supplied to the crucible 5 in a hydrogen atmosphere, and the heater is heated. 4, the raw material M is heated to about 1500 ° C. and melted to form fused quartz Mm, which is extruded from an annular gap 10 formed between the flange 8 a and the mold 9 at the bottom of the crucible 4.
[0027]
At this time, since the gap 10 is formed in an annular shape, the fused quartz Mm extruded from the gap 10 becomes tubular, and is cooled to about 1000 ° C. to produce the continuous quartz tube 3.
[0028]
The continuously manufactured quartz tube 3 is constantly imaged simultaneously by CCD line sensors 11a, 11b, and 11c that image the outer periphery of the quartz tube 3 by dividing the quartz tube into approximately three parts, and image information obtained by the CCD line sensors 11a, 11b, and 11c. Is sent to the image processing device 12. The range of the quartz tube 3 directly imaged by the CCD line sensor 11a is on the side of the CCD line sensors 11a, 11b and 11c on the extension line L of the diameter, and is a portion of about 120 degrees centering on the radiation ray Sa. The outside of the imaging range of the above-mentioned CCD line sensor 11a, that is, the portion of the extension line L of the diameter on the side opposite to the CCD line sensor 11a is imaged by the CCD line sensor 11b and the CCD line sensor 11c via the reflection mirror 16b or 16c. Is done.
[0029]
Since the quartz tube 3 moves downward continuously, the quartz tube 3 is imaged as a surface by the CCD line sensors 11a, 11b, and 11c, and is image-processed by the image processing device 12 at regular intervals. That is, in the image processing device 12, a certain section of the gray image of the quartz tube 3 that moves continuously is taken out, and the state of the bubbles in this section, that is, the size of the bubble B (width w, length L) and the number of bubbles B are calculated.
[0030]
On the other hand, since the melting furnace 2 is used in a hydrogen atmosphere, bubbles B as shown in FIG.
[0031]
When the bubble B exists in the quartz tube 3, the size (width w, length 1) of the bubble B is analyzed by the arithmetic processing of the image processing device 12, and when the predetermined size, for example, the width w is 0.2 mm or more, The bubble B is displayed on the monitor 13 displaying an image at all times, and an automatic sorter (not shown) is operated via the sorter control unit 15, and the quartz tube 3 containing the bubble B is regarded as a defective product. exclude. Further, the conditions inside the melting furnace 2 are changed by controlling the amount of electric power supplied to the heater 4 via the control device 14 and the generation of bubbles B is suppressed.
[0032]
FIG. 4 shows an image displayed on the monitor 13 by combining images in three directions taken from the three CCD line sensors 11a, 11b, and 11c. Since the quartz tube 3 immediately after being discharged from the melting furnace 2 is at a high temperature of about 1000 ° C., the quartz tube 3 itself emits light. It shines brighter than the part. Since the portion where the bubble B exists is brighter and brighter than the portion where the bubble B does not exist, the images Pa 1, Pb and Pc of the monitor 13 as shown in FIG. can get. The image Pa is an image directly captured by the CCD line sensor 11a, and the images Pb and Pc are captured by the CCD line sensors 11b and 11c via the reflection mirrors 16b and 16c, respectively, and are subjected to mirror inversion processing in the image processing device 12. Image.
[0033]
The same inspection is continued successively, and the bubble inspection of the quartz tube 3 is performed unmanned and automatically, and the quartz tube 3 is continuously manufactured.
[0034]
As described above, in the present embodiment, the three CCD line sensors 11a, 11b, 11c are arranged on the same side with respect to the extension line L of the diameter of the quartz tube 3, and the two reflection mirrors 16a, 16b Is arranged on the opposite side of the extension line L, the inspection and adjustment of the CCD line sensors 11a, 11b, 11c are easy, and the space for installing the bubble detecting device for the quartz tube can be saved.
[0035]
Next, another embodiment will be described.
[0036]
FIG. 5 shows a quartz tube bubble detecting device 17 according to another embodiment of the present invention , in which a first CCD camera 18a and a first CCD camera 18a are placed on two orthogonal extension lines La and Lb of the quartz tube 3. A second CCD camera 18b is provided. The CCD camera 18a is disposed at a certain distance Da from the center of the quartz tube 3, and the distance Da is, for example, 2000 mm when the diameter of the quartz tube 3 is 25 mm, and the diameter of the quartz tube 3 is 25 mm. When it is 50 mm, it is preferably 3000 mm.
[0037]
On the other hand, the CCD camera 18b and the reflection mirror 19b in the optical system have a certain separation distance db from the center of the quartz tube 3 and rotate at a certain angle θb clockwise from a plane perpendicular to the extension line Lb of the diameter. Is located in the position.
[0038]
The distance db between the center of the quartz tube 3 and the reflection mirror 19b needs to be 30 mm or more when the above-described distance Da is, for example, 2000 mm or 3000 mm, and desirably 30 mm to 100 mm.
[0039]
The above-mentioned constant angle θb is desirably 10 ° to 30 ° regardless of whether the diameter of the quartz tube 3 is 25 mm or 50 mm. If it is less than 10 °, for example, the images of P2b and P3b shown in FIG. 6B will overlap, and if it exceeds 30 °, either image P2b or P3b will be out of the field of view of the CCD camera 18b.
[0040]
As shown in FIG. 6A, the CCD camera 18a arranged as described above directly connects the front surface of the quartz tube 3 and the corresponding back surface thereof with the CCD camera 18a and the reflection mirror 19a in the optical system as shown in FIG. Image P2a and the image P3a reflected on the reflection mirror 19a, and the CCD camera 18b similarly similarly directly connects the front surface of the quartz tube 3 and the corresponding back surface via the reflection mirror 19b to the CCD camera of FIG. 18b of the image P2b, to the image shooting as image P3b caught on the reflecting mirror 19b.
[0041]
FIG. 7 shows 10 numerical values from 1 to 0 at equal intervals around the surface of the cooled product quartz tube 3, which are imaged by the quartz tube bubble detector 17 in FIG. 6 (a) is an image captured by the CCD camera 18a, and FIG. 6 (b) is an image captured by the CCD camera 18b.
[0042]
In this way, it can be seen that the two CCD cameras 18a and 18b and the two reflecting mirrors 19a and 19b accurately image the periphery of the quartz tube 3 surface.
[0043]
As described above, the bubble detecting device for the quartz tube of the present embodiment uses two CCD cameras 18a, 18b and two reflecting mirrors 19a, 19b, so that the space for installing the bubble detecting device for the quartz tube is saved. It is possible to reduce the number of imaging means and speed up image processing, and it is economical and efficient.
[0044]
【The invention's effect】
As described above, in the quartz tube bubble detection device according to the present invention, the bubble inspection is unmanned by the quartz tube bubble detection device using the imaging unit, thereby releasing the worker from dangerous work and performing a visual inspection. Inspection accuracy has been improved compared to the previous one, and online bubble inspection of quartz tubes has become possible by automation. In addition, it is an economical bubble detection device that does not require any special lighting because it is a bubble inspection using the light emission of the quartz tube itself. Further, when the imaging means and the reflection mirror are used in combination, the space for installing the bubble detecting device for the quartz tube can be saved.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view of a quartz tube bubble detecting apparatus according to the present invention.
FIG. 2 is a schematic diagram illustrating a main part of FIG. 1;
FIG. 3 is an explanatory view showing a state of bubbles contained in a quartz tube.
FIG. 4 is a reference diagram showing a state of bubbles displayed on a monitor.
FIG. 5 is a schematic view of a bubble inspection apparatus for a quartz tube according to another embodiment of the present invention.
Figure 6 is an explanatory diagram of an image that will be captured in the CCD camera of FIG.
[7] image photograph of a quartz tube that is captured by the CCD camera of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Quartz tube bubble detector 2 Melting furnace 3 Quartz crucible 4 Heater 5 Crucible 6 Refractory 7 Enclosure 8 Mandrel 8a Projection 9 Mold 10 Gap parts 11a, 11b, 11c CCD line sensor 12 Image processing device 13 Monitor 14 Control device 15 Separator control unit 16b, 16c Reflecting mirror 17 Foam detecting device 18a, 18b of quartz tube CCD camera 19a, 19b Reflecting mirror B Foam Da, db Separation distance L, La, Lb Extension line of diameter M Raw material powder Mm Fused quartz Pa , Pb, Pc, P2a, P2b Image P3a, P3b Reflection mirror image Sa Radiation ray θb Constant angle

Claims (3)

An imaging unit provided to face a quartz tube which is continuously extruded or drawn out of the quartz melting furnace in a tubular form, and which captures an image of a bubble present in the quartz tube; and receives an image signal of the bubble state from the imaging unit. An image processing apparatus for analyzing the image signal and measuring the state of the bubbles, and an output device for outputting processing information of the image processing apparatus, wherein the quartz tube has a bubble detector. Are arranged on the same side with respect to the extension of the diameter of the lens, two of the three imaging means are combined with a reflecting mirror, and the three imaging means are used to surround the outer peripheral position of the quartz tube. An apparatus for detecting bubbles in a quartz tube, characterized in that the apparatus can be imaged from the outside at substantially equal intervals in the direction. Three quartz tube according to claim 1, wherein the two reflecting mirrors and the imaging means disposed in the center, characterized in that disposed approximately 120 degree intervals on the outer peripheral side of the quartz tube of the imaging means Foam detection device. An imaging unit provided to face a quartz tube which is continuously extruded or drawn out of the quartz melting furnace in a tubular form, and which captures an image of a bubble present in the quartz tube; and receives an image signal of the bubble state from the imaging unit. An image processing apparatus for analyzing the image signal to measure the state of the bubbles, and an output device for outputting processing information of the image processing apparatus, a bubble detector of the quartz tube , each of the opposed surface of the quartz tube a first imaging means and the second iMAGING means disposed at intervals of approximately 90 degrees around the quartz tube to image the state of the foam on the opposite side with respect to the two image pickup means and the quartz tube The state of the bubbles on the back surface of the quartz tube which is disposed and substantially corresponds to the opposing surface of the quartz tube is photographed, and the first imaging means and the first reflection mirror in the optical system and the second imaging means and the optical system are in the optical system. a second reflecting mirror, said first imaging Stage is provided with a quartz tube with a predetermined distance, a predetermined angle from the plane perpendicular to the extension line of the second reflection mirror has a central constant distance between the quartz tube, and the diameter It is disposed at a rotated position, and the opposing surface and the back surface of the quartz tube are imaged by the first imaging unit and the second imaging unit imaging the opposing surface of the quartz tube and the first reflection mirror and the second reflection mirror. A bubble detector for a quartz tube, characterized in that it captures an image of a bubble state.

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