JPH02157179A - Image furnace - Google Patents

Abstract

PURPOSE:To determine the adequate supply electric power value to a heat source and to well control the temp. of the heat source with the image furnace to be utilized for crystal growth, etc., by providing a two-dimensional visible sensor or two-dimensional IR sensor and measuring the change in the two-dimensional shape of a melt zone part. CONSTITUTION:The following constitution is added to the image furnace which is provided with the heat source in the 1st focus part of a rotary elliptical reflecting mirror 101 and parts 102, 108, 103 to be heated in the 2nd focus part of the reflecting mirror 101 and forms the melt zone part 108 by concentrating the IR rays emitted from the above-mentioned heat source to the parts 102, 108, 103 to be heated to heat these parts: An image processing section which converts the shape of the melt zone part 108 obtd. from the two-dimensional visible sensor or two-dimensional IR sensor for receiving the light emitted from the above-mentioned melt zone part 108 to the time series of the two-dimensional image patterns and an electric power value determining section 13 which determines the supply electric power value to the heat source by using the prescribed computation equation based on plural pieces of the shape characteristic quantities (i.e., area, peripheral length, distribution of longitudinal and transverse lengths, etc.) of the melt zone part 108 obtd. from the above-mentioned time series of the two-dimensional image patterns are provided.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image furnace used for crystal growth, etc.

[Conventional technology]

In an image furnace, a heat source is placed at the first focal point of a reflecting mirror made of an ellipsoid of revolution, a sample is placed at the second focal point, and the infrared rays are concentrated to heat the sample. This device has a single-vessel circular type in which the reflecting mirror consists of only one spheroidal surface, and a bi-elliptic type in which the reflecting mirror consists of a combination of two spheroidal surfaces and shares a second focal point. Furthermore, there are various circular types in which the reflecting mirror is composed of a combination of three or more spheroidal surfaces and shares a second focal point.

Next, the structure of a conventional image furnace will be explained with reference to the drawings. FIG. 5 is a sectional view showing an example of the main part of a conventional bielliptical image furnace. As shown in the figure, this image furnace has heated parts 102, 108, and 103 integrated with the focal point of a reflecting mirror 101 placed on the outside. The object to be heated is placed on the upper chuck 104. Upper shaft 106. by lower chuck 105. Attached to lower shaft l-107. When the object to be heated is heated and melted, a molten zone 108 is formed between 102 and 1.03, that is, at the second focal point of the image furnace. The furnace core tube 109 isolates the object to be heated from the outside, fills the inside of the tube with atmospheric gas such as inert scum, creates a vacuum inside the tube, or protects the mirror surface of the reflecting mirror from the gas generated from the object to be heated. It is for. Furthermore, this is an observation window opened in a part of the image furnace to observe the molten zone 108, and an operator who performs crystal growth etc. should not watch the image of the molten zone 108 through this observation window 110 to observe changes. In this case, the temperature of the heat source (not shown) was controlled accordingly. However, this method has a problem in that the operator must constantly monitor the work. FIG. 6 is a sectional view showing another example of the main part of a conventional several-circular image furnace. For example, as proposed in Japanese Patent Publication No. 60-200889, the diameter of the molten zone is measured, and if there is a change in the diameter of the molten zone, the temperature of the heat source is automatically adjusted accordingly. A device has been proposed to control the That is, the difference between this image furnace and the above-mentioned example is that, as shown in FIG. 6, a line sensor 31 is connected to the end of the observation window 110 to measure the diameter of the molten zone. Further, the power value determination unit] 3 performs arithmetic processing on the value to calculate the power value to be supplied to the heat source. Then, the electrode controller 14 controls the temperature of the heat source by supplying an electrode corresponding to the power value to the heat source.

[Problem to be solved by the invention]

However, with the conventional method of measuring the diameter of the melted zone using the line sensor described above, there are cases where the diameter of the melted zone does not change but the length changes, or when the diameter of the part that is not measured is When the temperature of the heat source changes, an appropriate power supply value to the heat source cannot be determined, and the temperature of the heat source cannot be properly controlled.

In addition, in the conventional method using only visible sensors, in the case of a heated object whose brightness in the visible region decreases or hardly changes when melted, it is possible to detect the unmelted part of the heated object and the melted zone. Since the distinction is difficult, it has not been possible to determine an appropriate power supply value to the heat source, and the temperature of the heat source has not been well controlled.

Furthermore, in the conventional method, the power supply to the heat source is controlled directly using the supplied power value determined from the shape of the melting zone, so it is possible to set the temperature of the heat source without depending on the shape of the melting zone. However, it was also impossible to make delicate temperature adjustments.

The object of the present invention is to eliminate these conventional drawbacks.

[Means to solve the problem]

The image furnace of the first invention provides a heat source at a first focal point of a spheroidal reflector, a heated portion at a second focal point of the spheroidal reflector, and concentrates infrared rays emitted from the heat source. In an image furnace that heats the heated part to form a molten zone, a two-dimensional image of the shape of the molten zone is obtained from a two-dimensional visible sensor or a two-dimensional infrared sensor that receives light emitted from the heated part. an image processing unit that converts into a pattern time series; and an electric power that determines the power to be supplied to the heat source using a predetermined calculation formula based on a plurality of shape features of the melted zone obtained from the two-dimensional image pattern time series. Consists of a value determining section.

The image furnace of the second invention includes an image processing unit that converts the shape of the melted zone obtained from the two-dimensional sensor into a two-dimensional image pattern time series, and a plurality of melted zone parts determined from the two-dimensional image pattern time series. a power value determination unit that determines the power to be supplied to the heat source using a predetermined calculation formula based on the shape feature values;
It is comprised of a control switching section that switches between using and not using the power value to be supplied to the heat source determined by the power value determining section.

〔Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of the main part of an image furnace showing a first embodiment of the present invention. As shown in FIG. 1, this image furnace has a two-dimensional visible sensor 12 connected to the end of an observation window 110. An example of a two-dimensional visible sensor is a CCD.
Possibly a camera. Here, the light emitted from the melted zone 108 passes through the observation window 1]0, and the two-dimensional visible sensor 12
The image data is converted into two-dimensional image data by , and sequentially sent to the power value determining section 13 . The power value determining unit 1B determines the power value to be supplied to the heat source based on the two-dimensional image data, and the value is sent to the power controller]4.

The power controller 14 supplies power corresponding to the received value to the heat source.Other than this, the power controller 14 is the same as the conventional example.The power controller 14 is a well-known technology in the field of automatic control. A detailed explanation will be omitted since it is different from the essence of the present invention.Furthermore, a description of the power value determination unit 13 will be given later.

FIG. 2 is a sectional view of the main part of an image furnace showing a second embodiment of the present invention. In this image furnace, the two-dimensional visible sensor 12 shown in the previous embodiment is replaced with a two-dimensional infrared sensor 21. Other than that, it is the same as the conventional example. An example of this two-dimensional infrared sensor is an infrared camera.

However, since the core tube 109 has the property of absorbing a lot of infrared rays, it may be difficult or impossible to determine the shape of the molten zone. In this case, the furnace core tube 109 does not need to be used.

FIG. 3 is a sectional view of the main part of an image furnace showing a third embodiment of the present invention. This image furnace of the first embodiment is provided with a control changeover switch section 15 and a power value designation section 16 connected thereto between the power value determination section 13 and the power controller 14.

This control changeover switch section 15 switches whether the data to be sent to the power controller 14 is the power value from the power value determining section 13 or the power value from the power value specifying section 16. The power specifying unit 16 may be, for example, an operation keyboard capable of inputting power values, a storage device that stores power values in advance, or the like.

Next, the power determining section 13 will be explained. FIG. 4 is a block diagram showing the power value determination unit]3. The two-dimensional image data is sequentially subjected to pre-processing such as digitization, noise removal, and binarization in the image pre-processing unit, converted into a two-dimensional image pattern time series, and sent to the feature extraction unit 132. The feature extraction unit 132 extracts the two-dimensional image pattern time series from the two-dimensional image pattern time series.
A trace amount of shape, for example, an area S, of the melted zone [08] is calculated and sent to the arithmetic processing section 133. The arithmetic processing section 133 performs arithmetic processing using constants stored in advance in the parameter storage section 134 to calculate the power value E. As an example of the calculation process, the power value E calculated by the equation (1) is sent to the power controller 14. The image preprocessing unit]-31 and the feature extraction unit 32 are well-known techniques in the field of image processing, and are different from the essence of the present invention, so a detailed explanation will be omitted.

In this example, area was used as the shape property trace amount, but
Other features, such as surrounding equipment, vertical and horizontal distribution, moment 1
It is obvious that a plurality of distances from the center of gravity to the outer contour may be used. Further, although the equation (]), which is a linear linear equation, is used as the calculation process, it is obvious that a quadratic equation, a cubic equation, or a nonlinear calculation may be performed.

Further, although the present embodiment has been described with respect to a several-circular image furnace, the present invention can be implemented in the same manner with a single-phase circular type or a multi-path circular type image furnace.

Regarding automatic control technology, for example, "Basics and Applications of Automatic Control" published by Jikkyo Publishing Co., Ltd. in 1970, and regarding image processing technology, for example, published by Kyoritsu Publishing Co., Ltd. in 1980. It is described in detail in "Applied Image Analysis".

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The image furnace of the first invention is equipped with a two-dimensional visible sensor that measures changes in the two-dimensional shape of the molten zone.By this, an appropriate power supply value to the heat source can be determined, and the temperature of the heat source can be adjusted. Good control became possible.

The image furnace of the second invention is equipped with a two-dimensional infrared sensor to measure the two-dimensional shape of the object to be heated, which cannot be measured visually, to determine an appropriate power supply value to the heat source. It is now possible to better control the temperature.

The image furnace of the third invention has a control switching function that allows specifying whether the value used for power control is the power value determined by the power value determining section or the value determined manually or by other means. By providing this section, it became possible to set the temperature of the heat source independent of the shape of the melting zone, and it also became possible to finely adjust the temperature.

101... Reflecting mirror, 102, 108. 103... Heated object, 108... Melting zone, 1.04, 105...
Upper and lower chucks, 106, 107... Upper and lower shafts, 10
9... Furnace core tube, 110... Observation window, 12... Two-dimensional visible sensor,] 3... Power value determination unit, 14... Power controller, 15 - Control changeover switch unit, 16...
- Power value designation section, 21... two-dimensional infrared sensor, 131
...Image preprocessing unit, 132...Feature amount extraction unit, 13
3... Arithmetic processing unit, 134/Parameter storage unit, 31
...Line sensor.

Claims (1)

[Claims] 1. A heat source is provided at a first focal point of the spheroidal reflecting mirror, and a heated portion is provided at a second focal point of the spheroidal reflecting mirror;
In an image furnace that concentrates infrared rays emitted from the heat source to heat the heated part and form a molten zone, melting obtained from a two-dimensional visible sensor or a two-dimensional infrared sensor that receives light emitted from the heated part an image processing unit that converts the shape of the band portion into a two-dimensional image pattern time series;
An image characterized by having a power value determination unit that determines the power value to be supplied to the heat source using a predetermined calculation formula based on a plurality of shape feature values of the melted zone portion obtained from the dimensional image pattern time series. Furnace. 2. The image furnace according to claim 1, further comprising a control switching unit that switches between using and not using the power value to be supplied to the heat source determined by the power value determining unit.