TWI645166B - System for measuring a surface height of a liquid and method for measuring a surface height of a liquid - Google Patents

Abstract

The invention provides a liquid surface height detection system for measuring the height of the liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield and a crucible. The molten soup is placed in the crucible and the thermal shield is located above the crucible. The liquid level detection system includes a hollow cylinder, a light source, a light guide rod, an image capturing unit, and an image analysis unit. The hollow cylinder is used to be set in a thermal mask, the light source is used to project the light beam, and the light guide rod is used to guide the light. The light beam is guided so that the light beam is projected on the molten soup to form a virtual image of the liquid surface or a subsurface liquid image. The image capture unit is used to capture the liquid surface to obtain an image to be analyzed. The image analysis unit signal is connected to the image capture unit and used to analyze the image to be analyzed. Analyze the image to get the height. This allows the liquid level to be calculated and monitored.

Description

Liquid level detection system and method

The invention relates to a liquid surface height detection system and a liquid surface height detection method, and more particularly to a liquid surface height detection system and a liquid surface height detection method applied to a crystal growth device.

The Czochralski process is a method commonly used in the industry to produce crystal ingots. The silicon material is first put into a crucible, and then the silicon material is heated to a molten state to form a molten soup, and the crystals at the ends are This kind of positioning rod is immersed in the molten soup, and by slowly pulling and rotating the positioning rod, a cylindrical single crystal ingot can be obtained at the end of the positioning rod.

In such a method for generating an ingot, a heat shield is usually provided above the crucible (that is, around the single crystal ingot) to prevent heat radiation from affecting the formation of the single crystal ingot.

In addition, in order to improve the quality of the ingot, the interval between the thermal mask and the molten liquid level in the crucible needs to be controlled. Therefore, the height of the liquid level needs to be continuously measured during the middle of the ingot generation.

Some people use the laser red distance measuring device to measure the liquid surface position in a non-contact liquid level manner. However, due to the high temperature in the crystal growth device, there is a large amount of infrared in the crystal growth device, which will affect the laser red. The measurement effect of the optical ranging device makes the measurement result out of alignment.

In view of this, how to effectively measure the height of the molten liquid level in the crystal growth device has become the goal of related industry efforts.

The invention provides a liquid surface height detection system and a liquid surface height detection method. An accurate liquid surface height can be calculated through a hollow cylinder, a light guide rod, an image capturing unit, and an image analysis unit.

According to one aspect of the present invention, a liquid surface height detection system is provided for measuring a height of a liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield, a crucible, and a molten soup volume. It is placed in the crucible, and the thermal shield is located above the crucible. The liquid level detection system includes a hollow cylinder, a light source, a light guide rod, an image capture unit and an image analysis unit. The hollow cylinder is arranged on the thermal mask. Inside, the light source is used to project a light beam, and the light guide rod is arranged in the hollow cylinder and used to guide the light beam, so that the light beam is projected on the molten soup to form a liquid surface light shadow or a subsurface liquid light shadow virtual image, and an image capturing unit It is used to shoot the liquid surface light shadow or a subsurface liquid light shadow virtual image to obtain an image to be analyzed. The image analysis unit signal is connected to the image capture unit and is used to analyze the image to be analyzed to obtain the height.

Therefore, a hollow cylinder is used to surround the light guide rod, so that after the light guide rod guides the light, a small area of the liquid surface light shadow or a virtual shadow image under the liquid surface can be formed. In order to avoid distortion due to the influence of the liquid surface gradient, it is more helpful to improve the accuracy of the liquid level determination.

According to the aforementioned liquid surface height detection system, the hollow cylinder and the light guide rod may be inclined to the liquid surface, or the hollow cylinder and the light guide rod may be perpendicular to the liquid surface. Or the light guide rod may include a first section and a second section, the first section is for the light beam to enter, the second section guides the light beam to exit, and the first section protrudes from the hollow cylinder. Or the first section of the light guide rod may be a spherical structure and protrude from a hollow cylinder. Or the first segment and the second segment may be at an angle, and the first segment is parallel to an incident direction of the light beam. Or the diameter of the light guide rod can be 2 mm or more and 8 mm or less. Or the aforementioned liquid level detection system may further include a fixing member for fixing the hollow cylinder on the heat shield. Or the material of the hollow cylinder may be one of molybdenum, tungsten, tantalum, niobium, vanadium, chromium, titanium, zirconium or an alloy of the above materials.

According to another aspect of the present invention, a liquid surface height detection method is provided for measuring a height of a liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield, a crucible, and a molten soup. It is contained in the crucible, and the thermal shield is located above the crucible. The method for detecting the liquid level includes the following: providing a hollow cylinder to be arranged in the thermal shield; providing a light source to project a light beam; providing a light guide rod to guide the light beam, and The light beam is projected on the molten soup to form a liquid surface light shadow or the light guide rod emits light and forms a subsurface liquid light and shadow virtual image; provides an image capture operation, and uses an image capture unit to capture the liquid surface light shadow and the subsurface liquid light and shadow virtual image To obtain at least one of the images to obtain an image to be analyzed; and to provide an image analysis operation, using an image analysis unit to analyze the image to be analyzed to obtain the height.

According to the aforementioned method for detecting the height of the liquid surface, an end surface of the hollow cylinder is projected on the molten soup to form a virtual image of the cylinder below the liquid surface on the image to be analyzed. It may include a first circle representing a virtual image of a cylinder below the liquid surface and a second circle representing light and shadow on the liquid surface. In the image analysis operation, the image analysis unit finds the center of the first circle and the center of the second circle to calculate height. Or the image to be analyzed may have an x-axis direction and a y-axis direction, and the image analysis unit calculates the height according to a distance between at least one of the center of the first circle and the center of the second circle along the x-axis direction and the y-axis direction.

100‧‧‧Liquid level detection system

100a‧‧‧Liquid level detection system

100b‧‧‧Liquid level detection system

100c‧‧‧Liquid level detection system

110, 110a‧‧‧ hollow cylinder

110b, 110c‧‧‧hollow cylinder

110d‧‧‧hollow cylinder

120, 120a‧‧‧light guide

120b, 120c‧‧‧light guide

121‧‧‧ second paragraph

122, 122b, 122c ‧‧‧ first paragraph

130, 130a‧‧‧ light source

140, 140a‧‧‧Image analysis unit

140b, 140c‧‧‧Image Analysis Unit

150, 150d‧‧‧Fixed parts

160, 160a‧‧‧Image capture unit

160b, 160c‧‧‧Image capture unit

221‧‧‧Face

222‧‧‧ Outer cone section

300‧‧‧Liquid level detection method

310, 320, 330‧‧‧ steps

340, 350‧‧‧ steps

L1, L2‧‧‧‧Beams

M1, M2‧‧‧ cylinder virtual image below the liquid surface

N1, N2, N3 ‧‧‧ liquid surface light and shadow

C1, C3‧‧‧first circle

C2, C4, C5, C6‧‧‧Second Circle

C7, C8‧‧‧ Third Round

D1, D2, D3, D4‧‧‧ distance

P1, P2, P3, P4‧‧‧ to be analyzed

P5, P6, P7, P8‧‧‧ to be analyzed

Q1‧‧‧ Virtual image of light and shadow under the liquid surface

S‧‧‧Liquid level

W‧‧‧ molten soup

200, 200a‧‧‧Growth device

210‧‧‧ Crucible

220, 220a, 220d‧‧‧ Thermal Mask

200b, 200c‧‧‧Growth device

x‧‧‧ axis

y‧‧‧axis

θ‧‧‧ angle

FIG. 1A shows a schematic diagram of a liquid level detection system for measuring the height of a liquid surface according to an embodiment of the present invention; FIG. 1B shows an image to be analyzed captured by the image capturing unit of FIG. 1A Schematic diagram; Figure 2A shows another schematic diagram of the liquid surface height detection system of Figure 1A used to measure the liquid surface height; Figure 2B shows the schematic diagram of the image to be analyzed captured by the image capture unit of Figure 2A Figure 3A shows a schematic diagram of a liquid surface height detection system for measuring the height of a liquid surface according to another embodiment of the present invention; Figure 3B shows a sample to be captured by the image capturing unit of Figure 3A Analysis image diagram; Figure 4A shows another schematic diagram of the liquid surface height detection system of Figure 3A used to measure the liquid surface height; Figure 4B shows the image to be analyzed captured by the image capture unit of Figure 4A Image diagram; Figure 5A shows a schematic diagram of a liquid level detection system for measuring the height of a liquid surface according to yet another embodiment of the present invention; Figure 5B shows the image captured by the image capturing unit of Figure 5A Figure 6A shows another schematic diagram of the liquid level detection system used in Figure 5A to measure the height of the liquid surface; Figure 6B shows the image captured by the image capture unit of Figure 6A A schematic diagram of the image to be analyzed; FIG. 7A illustrates a schematic diagram of a liquid level detection system for measuring the height of a liquid surface according to a further embodiment of the present invention; FIG. 7B illustrates an image captured by an image capturing unit of FIG. 7A Figure 8A shows the schematic diagram of the image to be analyzed; Figure 8A shows another schematic diagram of the liquid level detection system used in Figure 7A to measure the liquid level; Figure 8B shows the image captured by the image capture unit of Figure 8A Figure 9 is a schematic diagram of the image to be analyzed; FIG. 9 is a schematic diagram of a fixing member and a hollow cylinder set in a thermal mask according to a liquid level detection system according to still another embodiment of the present invention; and FIG. 10 is a schematic diagram of FIG. A liquid according to another embodiment of the present invention A step-by-step flowchart of the surface height detection method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For the sake of clarity, many practical details will be explained in the following description. The reader should understand, however, that these practical details should not be used to limit the invention. That is, in some embodiments of the present invention, these practical details are unnecessary. In addition, in order to simplify the drawings, some conventional structures and elements will be shown in the drawings in a simple and schematic manner; and repeated elements may be represented by the same number.

Please refer to FIG. 1A and FIG. 1B, wherein FIG. 1A shows a schematic diagram of a liquid level detection system 100 for measuring the height of the liquid level S according to an embodiment of the present invention, and FIG. 1B shows FIG. 1A A schematic diagram of the image P1 to be analyzed captured by the image capturing unit 160. The liquid level detection system 100 is used to measure a height of a liquid level S of a molten soup W in a crystal growth device 200. The crystal growth device 200 includes a thermal shield 220 and a crucible 210, and the molten soup W is contained in The crucible 210 is located above the crucible 210.

The liquid level detection system 100 includes a hollow cylinder 110, a light source 130, a light guide rod 120, an image capture unit 160, and an image analysis unit 140. The hollow cylinder 110 is used to be disposed in a thermal shield 220. An end surface of the hollow cylinder 110 is projected on the molten soup W to form a subsurface liquid cylinder virtual image M1. The light source 130 is used to project a light beam L1, and the light guide rod 120 is used to guide the light beam L1 so that the light beam L1 is projected on The molten soup W is formed to form a liquid surface light and shadow N1, and the image capturing unit 160 is used to photograph the liquid surface S, so that the virtual image M1 and liquid light shadow N1 of the cylinder below the liquid surface are formed into an image P1 to be analyzed, and the image analysis unit 140 signals The image capturing unit 160 is connected to analyze the image P1 to be analyzed to obtain the height.

Thereby, a virtual cylinder image M1 and a light surface shadow N1 below the liquid surface are formed through the hollow cylinder 110 and the light guide rod 120, and the virtual image M1 of the cylinder below the liquid surface and the light surface shadow N1 are imaged by the image capturing unit 160 as The image P1 to be analyzed is finally analyzed by the image analysis unit 140 to obtain the height of the liquid surface S. The liquid level detection system 100 and its height measurement principle will be described in more detail later.

The hollow cylinder 110 is disposed on an inner surface of the thermal shield 220 and is adjacent to the lower edge of the thermal shield 220. The light guide rod 120 is received in the hollow cylinder 110. In more detail, the thermal shield 220 of the crystal growth device 200 may include a straight surface section 221 and an outer expanding cone section 222, the straight section 221 is connected to the outer expanding cone section 222, and the liquid level detection system 100 is more A fixing member 150 is included to fix the hollow cylinder 110 to the straight section 221, and one end of the hollow column 110 is as flush as possible with the edge of the straight section 221. In this embodiment, the fixing member 150 is a linear body. The wire body is made of molybdenum.

The light guide rod 120 includes a first segment 122 and a second segment 121. The first segment 122 and the second segment 121 are at an angle θ. The first segment 122 is used for the light beam L1 to enter, and the second The segment 121 guides the light beam L1 to be emitted, the first segment 122 is parallel to an incident direction of the light beam L1, and the light guide rod 120 may be made of quartz material. That is, the light guide rod 120 is a bent rod body, and the first segment 122 is matched with the incident position of the light beam L1 so that the light beam L1 is more effectively guided to the liquid surface S to form a clear liquid surface light shadow N1. . When the light guide rod 120 is contained in the hollow cylinder 110, the second section 121 is located in the hollow cylinder 110, and the first section 122 is exposed in the hollow. The cylindrical body 110, such a bent arrangement, also allows the light guide rod 120 to be directly accommodated in the hollow cylindrical body 110 without the risk of falling.

Preferably, the material of the hollow cylinder 110 is molybdenum. When the light guide rod 120 is accommodated in the hollow cylinder 110, the inner wall of the hollow cylinder 110 can reflect the light beam L1, and the light leaked from the light guide rod 120 The light is reflected back to the light guide rod 120, and thus helps guide the light beam L1 to the liquid level S. The light source 130 may be a laser light source, which has a strong intensity and good directivity, and it is easy to form a clear liquid surface light shadow N1 on the liquid surface S. In addition, molybdenum has a high melting point and is suitable for use in a high temperature environment.

In this embodiment, since the side wall of the thermal shield 220 is composed of a straight face section 221 and an outer cone section 222, and the hollow cylinder 110 is disposed on the straight section 221, the hollow pillar 110 and the light guide rod 120 are both It is perpendicular to the liquid surface S, but in other embodiments, the hollow cylinder 110 and the light guide rod 120 may not be perpendicular to the liquid surface S, and may be arranged in an inclined manner according to the shape of the heat shield 220, but a hollow cylinder is preferred. The body 110 needs to be disposed on the inner surface of the heat shield 220 and adjacent to the lower edge of the heat shield 220, so that the hollow cylinder 110 can be smoothly imaged without being blocked by the heat shield 220. The light guide rod 120 may not be disposed in the hollow cylinder 110, but may be placed elsewhere in the thermal shield 220, as long as the light beam L1 can be guided to the liquid surface S for imaging.

The image capturing unit 160 may be disposed above the thermal mask 220, so that the liquid surface S can be smoothly captured. As shown in FIG. 1B, the image P1 to be analyzed includes the virtual image M1 representing the cylinder below the liquid surface. A first circle C1 and a second circle C2 representing the light surface shadow N1.

The image analysis unit 140 may include an image processor that performs edge detection on the image P1 to be analyzed to find the boundary between the first circle C1 and the second circle C2, and then finds the first circle C1 and The center of the second circle C2 is used to calculate the distance D1 between the two centers. As shown in Figure 1B, the image P1 to be analyzed has an x-axis direction and a y-axis direction, and the distance D1 is in the y-axis direction. Distance. Through this distance, the actual height of the liquid level S can be obtained by comparing the pre-established table and data.

It should be particularly noted here that the light guide rod 120 guides the light beam L1 so that the light exit end of the second section 121 of the light guide rod 120 may also form a subsurface liquid and light virtual image (not shown) at the molten soup W at the same time, and be liquid. The subsurface cylinder virtual image M1 is surrounded, but in this embodiment, the subsurface cylinder virtual image M1 is used. However, the subsurface fluid light and shadow virtual image can also be used instead of the subsurface cylinder virtual image M1 as the image P1 and P2 to be analyzed. portion.

Please refer to FIG. 2A and FIG. 2B. FIG. 2A shows another schematic diagram of the liquid level detection system 100 of FIG. 1A for measuring the height of the liquid surface S, and FIG. 2B shows the image capture of FIG. 2A. A schematic diagram of the image P2 to be analyzed captured by the unit 160. As shown in FIG. 2A, the liquid level S drops, and the image capturing unit 160 captures the image P2 to be analyzed. At this time, the center distance between the first circle C1 and the second circle C2 on the image P2 to be analyzed is D2. For example, if the height of the molten liquid level S decreases by h, the level of the liquid surface light shadow N1 will decrease by a height of h from the original position, and the virtual image of the cylinder under the liquid surface M1 will decrease by a height of 2h from the original position. The distance between the virtual images M1 below the cylinder will further increase the length of h, so the distance D2 in the image P2 to be analyzed will be greater than the distance D1 in the image P1 to be analyzed.

It can be seen from FIG. 2B that the drop of the liquid level S will change the center distance between the first circle C1 and the second circle C2. Therefore, the height of the liquid surface S can be detected through the calculation of the center distance.

It should be particularly explained here that the liquid surface light and shadow N1 formed by the light beam L1 is a reflected light spot of the light beam L1 on the liquid surface S, so regardless of the change in the height of the liquid surface, the liquid surface light and shadow N1 will be located on the liquid surface S. The virtual cylinder M1 below the liquid surface of the hollow cylinder 110 is formed by the imaging principle of a flat mirror. Therefore, the distance between the virtual cylinder M1 below the liquid surface and the liquid surface S is equal to the distance between the hollow cylinder 110 and the liquid surface S (the image distance is equal to Object distance), so the virtual image of the cylinder below the liquid surface M1 can be regarded as being located below the liquid surface S, and the distance from the liquid surface S will change with the distance between the liquid surface S and the hollow cylinder 110. Therefore, when the liquid level S decreases, the virtual image M1 of the cylinder below the liquid level will become smaller, and the distance relationship with the liquid surface light and shadow N1 will change. The first circle C1 and the second circle C2 are not necessarily perfect circles. They will be slightly rounded due to the shooting angle of the image capturing unit 160, and the shooting angle will make the image P1 to be analyzed include the hollow cylinder 110. , But these parts can be removed by the image analysis unit 140 without affecting the acquisition of the center of the circle.

The so-called pre-established form and data means that after the liquid level detection system 100 is installed in the crystal growth device 200, the image to be analyzed when the liquid level S is highest is first obtained, and the corresponding center distance is calculated, and then the process is started. Let the height of the liquid surface S decrease, and calculate the corresponding center distance again. In this way, continuously reduce the height of the liquid surface S and calculate the center distance. Finally, a comparison table of the center distance and the height of the liquid surface S can be made.

Please refer to FIG. 3A, FIG. 3B, FIG. 4A, and FIG. 4B, where FIG. 3A illustrates a liquid surface height according to another embodiment of the present invention. The detection system 100a is a schematic diagram for measuring the height of the liquid surface S. FIG. 3B is a schematic diagram of the image P3 to be analyzed captured by the image capturing unit 160a of FIG. 3A, and FIG. 4A is a diagram of the liquid of FIG. 3A. The surface height detection system 100a is another schematic diagram for measuring the height of the liquid surface S. FIG. 4B is a schematic diagram of the image P4 to be analyzed captured by the image capturing unit 160a of FIG. 4A.

The crystal growth device 200a and the crucible 210a are similar to the crystal growth device 200 and the crucible 210 in the above FIG. 1A, but the structure of the heat shield 220a is different from that of the heat shield 220. It has only an externally expanding cone section, and the liquid surface height The detection system 100a is similar to the liquid level detection system 100 in the above FIG. 1A, and includes a hollow cylinder 110a, a light source 130a, a light guide rod 120a, an image capture unit 160a, and an image analysis unit 140a. The hollow cylinder 110a is disposed on the outer expanding cone section, and the light guide rod 120a is not bent. In this embodiment, because the thermal shield 220a is inclined, the hollow cylinder 110a and the light guide rod 120a are also inclined. Therefore, the light guide rod 120a does not need to have an angle between the first section and the second section. To match the incidence of the light beam L2.

The end surface of the hollow cylinder 110a is projected on the molten soup W to form a virtual image M2 of the cylinder below the liquid surface. The light guide rod 120a guides the light beam L2 so that the light beam L2 is projected on the molten soup W to form the liquid surface light shadow N2. The light rod 120a and the liquid surface S have an inclined relationship. Therefore, in the images P3 and P4 to be analyzed captured by the image capturing unit 160a, the centers of the first circle C3 and the second circle C4 will have a distance in the x-axis direction and The distance in the y-axis direction. In this case, when the height of the liquid surface S changes, for example, when the height of the liquid surface S shown in FIG. 4A decreases, the distances between the centers of the first circle C3 and the second circle C4 in the x-axis direction and the y-axis The distance in each direction changes, so you can choose the distance on one of the axes Change to detect the height of the liquid level S. In the present embodiment, the distances D3 and D4 in the x-axis direction are selected to confirm the falling state of the liquid level S.

In order to further confirm the height of the liquid level S, the distance in the x-axis direction and the distance in the y-axis direction of the center of the first circle C3 and the second circle C4 can be calculated at the same time, and the distance in the x-axis direction can be estimated A height of the liquid surface S is estimated from a distance in the y-axis direction, and the two heights are compared to obtain a more accurate liquid surface S height.

As described in the previous embodiment, the light guide rod 120a guides the light beam L2 so that the light exit end of the second section of the light guide rod 120a may also form a subsurface liquid and light virtual image (not shown) at the molten soup W at the same time, The lower cylinder virtual image M2 is surrounded, but in this embodiment, it is represented by the lower cylinder virtual image M2, but the subsurface fluid light and shadow virtual image can also be used to replace the subsurface cylinder virtual image M2 as part of the images P3 and P4 to be analyzed. .

Please refer to FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B, where FIG. 5A shows a schematic diagram of a liquid level detection system 100b for measuring the height of the liquid level S according to yet another embodiment of the present invention. Figure 5B shows the schematic image P5 of the image to be analyzed captured by the image capturing unit 160b of Figure 5A, and Figure 6A shows the liquid level detection system 100b of Figure 5A for measuring the height of the liquid level S. In another schematic diagram, FIG. 6B is a schematic diagram of the image P6 to be analyzed captured by the image capturing unit 160b of FIG. 6A.

The crystal growth device 200b is similar to the crystal growth device 200 in FIG. 1A, and the liquid level detection system 100b is similar to the liquid level detection system 100 in FIG. 1A, but the light guide rod 120b is not bent, and the first The segment 122b has a spherical structure and protrudes from the hollow cylinder 110b.

In this embodiment, the light guide rod 120b guides the light beam so that the light beam is projected on the molten soup W to form the liquid surface light shadow N3. Therefore, the images to be analyzed P5 and P6 captured by the image capturing unit 160b will only represent the liquid surface light shadow N3. The second circle C5, C6, the image analysis unit 140b finds the center position of the second circle C5, C6, and can compare the established tables and data (that is, contains the liquid surface light and shadow N3 corresponding liquid that has been established in advance) The position data of the surface S is used as a comparison table) to obtain the actual height of the liquid level S corresponding to the current measurement, or to calculate the height change value of the liquid level S through the difference between the center positions of the second circles C5 and C6. As shown in FIG. 5A to FIG. 6B, for example, after the molten liquid level S of the molten soup W is lowered, the center position of the second circle C5 in the to-be-analyzed images P5 and P6 captured by the image capturing unit 160b is changed from the original The position moves to one side, for example, it moves downward and becomes the center position of the second circle C6. The direction of center movement of the second circles C5 and C6 varies according to the position of the image capturing unit 160b.

In this embodiment, since the hollow cylindrical body 110b surrounds the light guide rod 120b, after the light guide rod 120b guides the light beam, a liquid surface light shadow N3 with a small area can be formed, thereby preventing it from being affected by the liquid surface S slope (liquid surface). S near the crystal ingot is distorted due to the influence of the slope formed by the surface tension), which is more conducive to the improvement of the accuracy of the liquid level S height judgment. Preferably, the diameter of the light guide rod 120b may be greater than or equal to 2 mm and less than or equal to 8 mm. In this way, the second circles C5 and C6 of the images P5 and P6 to be analyzed may be complete small dots, which is advantageous. In the image analysis unit 140b, the center of the second circles C5 and C6 is found through the fitted circle method to reduce errors caused by image distortion. More preferably, the setting conditions of the image capturing unit 160b can be in accordance with the relationship between the incident angle and the reflection angle, which can help improve the second The clarity of circles C5, C6. In this embodiment, the to-be-analyzed images P5 and P6 automatically ignore possible subsurface liquid light and shadow virtual images and subsurface liquid cylinder virtual images (not shown), that is, even if there are subsurface liquid light and shadow virtual images and subsurface liquid cylinders, The virtual image is also filtered as noise, and it is analyzed and processed only for the liquid surface light and shadow N3.

Please refer to FIG. 7A, FIG. 7B, FIG. 8A, and FIG. 8B. FIG. 7A shows a schematic diagram of a liquid level detection system 100c for measuring the height of the liquid level S according to a further embodiment of the present invention. Figure 7B shows a schematic diagram of the image P7 captured by the image capturing unit 160c of Figure 7A, and Figure 8A shows the liquid level detection system 100c of Figure 7A for measuring the height of the liquid level S. In another schematic diagram, FIG. 8B is a schematic diagram of the image P8 to be analyzed captured by the image capturing unit 160c of FIG. 8A.

The crystal growth device 200c is similar to the crystal growth device 200b in FIG. 5A, and the liquid level detection system 100c is similar to the liquid level detection system 100b in FIG. 5A, but the first section 122c of the light guide rod 120c is not The protruding hollow cylinder 110c or only a slight protruding hollow cylinder 110c.

In this embodiment, the light guide rod 120c guides the light beam so that the light exit end of the second section of the light guide rod 120c generates bright light and projects it on the molten soup W to form a submerged light and shadow virtual image Q1. Therefore, the image capture unit 160c should wait for shooting. In the analysis images P7 and P8, only the third circles C7 and C8 representing the submerged light and shadow virtual image Q1 will be found. The image analysis unit 140c finds the position of the center of the third circle C7 and C8, and can obtain the corresponding correspondence against the established table. The actual height of the liquid surface S, or the difference in height of the liquid surface S is calculated through the difference between the center positions of the third circles C7 and C8. As shown in FIG. 7A to FIG. 8B, for example, after the molten surface W of the molten surface S drops, the image to be analyzed captured by the image capturing unit 160c In P7 and P8, the center position of the third circle C7 will move from the original position to one side. For example, it will move downward to become the center position of the third circle C8. The direction of the center of the third circle will follow the image. The location of the capture unit 160c varies. In this embodiment, the height of the liquid surface S is judged through the third circle C7, C8 formed by the virtual image Q1 under the liquid surface in the to-be-analyzed images P7 and P8. Therefore, as long as a laser light source with a general laser power is used, and the image capturing unit 160c does not need to be placed in a specific position, it is helpful to increase the flexibility of use. In this embodiment, the images to be analyzed P7, P8 automatically ignore the possible liquid light and shadow and the virtual image of the cylinder below the liquid surface (not shown), that is, even if there are liquid images and the virtual image of the cylinder below the liquid surface, they are also ignored. It is filtered as noise, and it is analyzed and processed only for the submerged light and shadow virtual image Q1.

Please refer to FIG. 9, which illustrates a schematic diagram of a fixing member 150 d and a hollow cylinder 110 d disposed on the thermal shield 220 d of a liquid level detection system according to still another embodiment of the present invention. The fixing member 150d may be an angular block structure. The shape of one side of the fixing member 150d corresponds to the inner wall of the thermal shield 220d and may abut the thermal shield 220d. The fixing member 150d may further include a hole for the screw member to pass through. The heat shield 220d is locked; in addition, the fixing member 150d further includes a setting hole for the hollow cylinder 110d to be set. In other embodiments, the hollow cylinder 110d is an installation hole that does not protrude from the fixing member 150d, and the light guide rod does not protrude from the installation hole, and is not limited to the above disclosure.

Please refer to FIG. 10, and also refer to FIGS. 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B. FIG. 10 shows a liquid surface according to another embodiment of the present invention. A step-by-step flowchart of the height detection method 300. The liquid level detection method 300 includes steps 310, 320, 330, 330, and 350.

In step 310, a hollow cylinder 110b, 110c is provided and disposed in the thermal shield.

In step 310, a light source is provided to project a light beam. Preferably, the light source is an electro-radiation light source.

In step 330, a light guide rod 120b, 120c is provided to guide the light beam, so that the light beam is projected on the molten soup W to form the liquid surface light shadow N3 or the light guide rod 120c emits light and forms a subsurface liquid light shadow virtual image Q1. The light guide rods 120b and 120c may be disposed in the hollow cylinders 110b and 110c, and the first segment 122b may protrude from the hollow cylinder 110b or the first segment 122c may not protrude from the hollow cylinder 110c.

In step 340, an image capture operation is provided, and an image capture unit 160 is used to capture the liquid surface S to obtain the images P5, P6, P7, and P8 to be analyzed. The images to be analyzed P5, P6, P7, and P8 may include the second circles C5 and C6 representing the liquid light shadow N3 or the third circles C7 and C8 representing the virtual light shadow image Q1 below the liquid surface.

In step 350, an image analysis operation is provided, and an image analysis unit 140b, 140c is used to analyze the images P5, P6, P7, and P8 to be analyzed to obtain the height. The image analysis unit 140b can find the center of the second circles C5 and C6 to calculate the height, or the image analysis unit 140c can find the center of the third circles C7 and C8 to calculate the height.

In step 310, as shown in FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B, one end surface of the hollow cylinder 110 can be projected on the molten soup W In order to form a subsurface liquid cylinder virtual image M1. In step 320, the image P1, P2, P3, and P4 to be analyzed may include a first circle C1 and C3 representing a virtual image M1 of the cylinder below the liquid surface and a second circle C2 and C4 representing one of the liquid surface light and shadow N1. The images P1, P2, P3, and P4 to be analyzed have an x-axis direction and a y-axis direction. In step 330, the image analysis unit 140 can find the center of the first circle C1 and the center of the second circle C2 to calculate the height. The image analysis unit 140 can calculate the height according to the center of the first circle C1 and the center of the second circle C2. The height is calculated by a distance along at least one of the x-axis direction and the y-axis direction.

Thereby, the height of the liquid surface S can be calculated through the distance along the y-axis direction between the first circle C1 and the second circle C2, and the status of the liquid surface S can be monitored at any time. Of course, as shown in FIG. 3A, FIG. 3B, FIG. 4A, and FIG. 4B, the height of the liquid surface S may be calculated from the distance in the x-axis direction between the first circle C3 and the second circle C4.

In other embodiments (not shown), the hollow cylinder 110b and the light guide rod 120b are not necessarily cylindrical, and can be any cylindrical shape or other shapes. At this time, the liquid surface light and shadow, and the liquid surface lower column can be calculated. The center of gravity or the center of gravity of the geometric shape of at least one of the body virtual image or the subsurface light and shadow virtual image is used as a reference for the comparison position. Furthermore, the first to third circles mentioned in the foregoing embodiments may be a perfect circle or an elliptical shape. In addition, the material of the hollow cylinder mentioned in the foregoing embodiments is one of materials such as molybdenum, tungsten, tantalum, tantalum, niobium, vanadium, chromium, titanium, zirconium and the like that can withstand high temperatures, or an alloy of the foregoing materials.

It can be known from the above embodiments that the liquid level detection system has the following advantages.

First, the light guide rod is arranged in a hollow cylinder, so that the liquid surface light shadow formed by the light guide rod on the liquid surface only exposes a round point because the light guide rod body is blocked by the hollow cylinder, which is conducive to image capture. Take the imaging of the unit and the judgment of the image analysis unit. In addition, it is not necessary to dig holes in the heat shield as in the conventional technology (such as digging holes in the side wall of the heat shield or the bottom plate extending inward), which can reduce the manufacturing and life of the heat shield and the heat. Field effect.

2. When the hollow cylinder is made of molybdenum or other metals or reflective materials, the light beam can be locked inside, which can make the light spot on the liquid surface formed by the light guide rod brighter.

3. When the liquid surface height calculation is performed by using the image formed by the light guide rod under the liquid surface and the virtual image, the normal or low power laser light source can be used to generate the virtual image under the liquid surface, and the image is captured. The unit can be set at any position where the liquid surface can be photographed, and has the advantage of flexible use.

4. Hollow cylinders and light guide rods can be installed vertically or obliquely. Even if the oblique installation will cause the entire hollow cylinder to have a larger reflection, the reflection is relatively insignificant compared to the entire light guide rod. , So it does not affect the interpretation of the image to be analyzed.

5. The fixing member can be used to fix the hollow cylinder. When the fixing member covers the light guide rod exposed from the upper end of the hollow column, the exposed part of the light guide rod can be prevented from imaging the liquid surface to interfere with the detection of the image. .

6. When the diameter of the light guide rod is greater than or equal to 2 mm and less than or equal to 8 mm, the deformation of the first circle formed on the image to be analyzed can be avoided, which is helpful for determining the center of the circle.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and retouches without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be determined by the scope of the attached patent application.

Claims (15)

A liquid surface height detection system for measuring a height of a liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield and a crucible, and the molten soup is contained in the crucible, and The thermal shield is located above the crucible, and the liquid level detection system includes: a hollow cylinder disposed in the thermal shield; a light source for projecting a light beam; a light guide rod disposed on the hollow column; The body is used to guide the light beam, so that the light beam is projected on the molten soup to form a liquid surface light shadow, a subsurface light shadow virtual image, or a subsurface liquid cylinder virtual image; an image capture unit is used to photograph the At least one of a liquid surface light shadow, a virtual image below the liquid surface, and a virtual image below the liquid surface to obtain an image to be analyzed; and an image analysis unit, a signal connected to the image acquisition unit and used to analyze the image to be analyzed Image to get that height. The liquid level detection system according to item 1 of the scope of the patent application, wherein the hollow cylinder and the light guide rod are inclined to the liquid level. The liquid surface height detection system as described in item 1 of the scope of patent application, wherein the hollow cylinder and the light guide rod are perpendicular to the liquid surface. The liquid level detection system according to item 1 of the scope of patent application, wherein the light guide rod includes a first section and a second section, the first section is for the light beam to enter, and the second section guides the light beam to exit And the first segment protrudes from the hollow cylinder. The liquid level detection system according to item 4 of the scope of patent application, wherein the first segment of the light guide rod is a spherical structure and protrudes from the hollow cylinder. The liquid level detection system according to item 4 of the scope of the patent application, wherein the first segment is at an angle with the second segment, and the first segment is parallel to an incident direction of the light beam. The liquid level detection system according to item 1 of the scope of patent application, wherein the diameter of the light guide rod is 2 mm or more and 8 mm or less. According to the liquid level detection system described in item 1 of the scope of the patent application, the system further includes a fixing member for fixing the hollow cylinder on the thermal shield. The liquid level detection system according to item 1 of the scope of application, wherein the material of the hollow cylinder is one of molybdenum, tungsten, tantalum, niobium, vanadium, chromium, titanium, and zirconium, or an alloy of the above materials. A liquid surface height detection method for measuring a height of a liquid surface of a molten soup in a crystal growth device, the crystal growth device includes a thermal shield and a crucible, and the molten soup is contained in the crucible, and The thermal shield is located above the crucible, and the method for detecting the height of the liquid surface includes: providing a hollow cylinder disposed in the thermal shield; providing a light source to project a light beam; providing a light guide rod to guide the light beam so that the The light beam is projected on the molten soup to form a liquid surface light shadow, or the light guide rod emits light and forms at least one of a virtual image of a liquid surface and a virtual image of a cylinder below the liquid surface; providing an image capture operation, using An image capture unit captures at least one of the liquid surface light and shadow, the liquid surface light and shadow virtual image, and the liquid column below the liquid surface virtual image to obtain an image to be analyzed; and provides an image analysis operation, which is analyzed by an image analysis unit The image to be analyzed to obtain the height. The method for detecting the height of a liquid surface as described in item 10 of the scope of patent application, wherein the image to be analyzed includes a first circle representing a virtual image of a cylinder below the liquid surface and a second circle representing a light and shadow on the liquid surface, and In the image analysis operation, the image analysis unit finds the center of the first circle and the center of the second circle to calculate the height. According to the liquid level height detection method described in item 10 of the scope of the patent application, wherein the image to be analyzed has an x-axis direction and a y-axis direction, the image analysis unit is based on the center of the first circle and the center of the second circle. The height is calculated along a distance between the x-axis direction and at least one of the y-axis directions. A liquid surface height detection system for measuring a height of a liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield and a crucible, and the molten soup is contained in the crucible, and The thermal shield is located above the crucible, and the liquid level detection system includes a hollow cylinder disposed in the thermal shield. The material of the hollow cylinder is molybdenum, tungsten, tantalum, niobium, vanadium, chromium, and titanium. One of the zirconium or the alloy of the above materials; a light source for projecting a light beam; a light guide rod disposed in the hollow cylinder and used to guide the light beam so that the light beam is projected on the melt The soup forms a liquid surface light and shadow, a liquid surface light and shadow virtual image, and a liquid surface below the cylinder virtual image; an image capture unit is used to shoot the liquid surface light and shadow, the liquid surface shadow and virtual image, and the liquid column below the liquid surface At least one of the virtual images to obtain an image to be analyzed; an image analysis unit, a signal connected to the image capture unit and used to analyze the image to be analyzed to obtain the height; and a fixing member for fixing the hollow cylinder to the Heat shield, and a side shape of the fixing member You should heat the inner wall of the mask. A liquid surface height detection system for measuring a height of a liquid surface of a molten soup in a crystal growth device. The crystal growth device includes a thermal shield and a crucible, and the molten soup is contained in the crucible, and The thermal shield is located above the crucible, and the liquid level detection system includes: a hollow cylinder disposed in the thermal shield; a light source for projecting a light beam; a light guide rod disposed on the hollow column; The body is used to guide the light beam, so that the light beam is projected on the molten soup to form a liquid surface light shadow, a subsurface light shadow virtual image, or a subsurface liquid cylinder virtual image; an image capture unit is used to photograph the At least one of a liquid surface light shadow, a virtual image below the liquid surface, and a virtual image below the liquid surface to obtain an image to be analyzed; and an image analysis unit, a signal connected to the image acquisition unit and used to analyze the image to be analyzed Image to obtain the height; wherein the light guide rod includes a first segment and a second segment, the first segment is for the light beam to enter, the second segment guides the light beam to exit, and the first segment is a spherical structure and Protrude the hollow cylinder. According to the liquid level detection system described in item 14 of the scope of patent application, it further includes a fixing member for fixing the hollow cylinder to the thermal shield, and a shape of a side of the fixing member corresponds to the inner wall of the thermal shield. .