CN110081981B - Temperature measuring method - Google Patents

本发明公开的温度测量方法，包括步骤：利用测温仪获得待测表面某测量点的温度值；利用摄像头同时获取该待测表面的图像；对获取的图像进行处理得到测量点的灰度值；获得温度测量值与灰度值之间的对应关系；以及获取待测点某时刻的图像，利用对应关系得到待测点该时刻的温度测量值。本发明的温度测量方法利用某测量点不同时段测量的温度值及图像灰度值建立对应关系，然后可移除测温仪，将待测点某时刻的图像灰度值代入对应关系中，即可算出该时刻温度值。并且，无需对每个炉台配备测温仪，本发明根据待测点的图像测其温度，无测量距离干扰，且测量范围仅为待测点周围小范围区域，反应灵敏且测量误差小，有助于提升测量精度。

The temperature measurement method disclosed by the invention comprises the steps of: using a thermometer to obtain a temperature value of a certain measurement point on the surface to be measured; using a camera to simultaneously acquire an image of the surface to be measured; processing the acquired image to obtain the gray value of the measurement point obtaining the corresponding relationship between the temperature measurement value and the gray value; and obtaining the image of the point to be measured at a certain moment, and using the corresponding relationship to obtain the temperature measurement value of the point to be measured at the moment. The temperature measurement method of the present invention establishes a corresponding relationship by using the temperature values measured at different time periods at a certain measurement point and the image grayscale value, and then the thermometer can be removed, and the image grayscale value of the point to be measured at a certain time is substituted into the corresponding relationship, that is, The temperature value at this moment can be calculated. Moreover, there is no need to equip each furnace table with a thermometer, the temperature of the point to be measured is measured according to the image of the point to be measured, and there is no interference from the measurement distance, and the measurement range is only a small area around the point to be measured, and the response is sensitive and the measurement error is small. Helps improve measurement accuracy.

Temperature measuring method

Technical Field

The invention belongs to the technical field of temperature measurement, and particularly relates to a temperature measurement method.

Background

Photovoltaic power generation is increasingly paid attention to and vigorously developed by countries in the world as one of green energy and main energy for human sustainable development. The monocrystalline silicon wafer is used as a basic material of photovoltaic power generation and has wide market demand. One common method for growing single crystal silicon is the czochralski method, i.e., in a single crystal furnace, a seed crystal is immersed into a melt contained in a crucible, and the seed crystal is pulled while rotating the seed crystal and the crucible to sequentially perform seeding, shouldering, shoulder rotating, diameter equalizing and ending at the lower end of the seed crystal to obtain a single crystal silicon rod.

In order to ensure that the crystal pulling is carried out stably, the temperature of the melt level in the furnace platform needs to be measured and controlled during the crystal pulling process. A common method for measuring the surface temperature of a melt is to measure the surface temperature of the melt by an external thermometer at a certain frequency. The control system adjusts the heating power according to the measurement result of the temperature measuring instrument to ensure that the surface temperature of the melt is within a preset range. The external thermometer is used for measuring the liquid level temperature, the distance between the thermometer and the surface to be measured is long, the anti-interference capability is poor, and the measurement precision is low. Moreover, each furnace platform is required to be provided with a special temperature measuring instrument, so that the cost is high.

Disclosure of Invention

The invention aims to provide a temperature measuring method to solve the problems that the precision of the existing temperature measuring result needs to be improved and the cost of temperature measuring equipment is high.

The technical scheme adopted by the invention is as follows: a method of temperature measurement comprising the steps of:

providing a temperature measuring instrument, and measuring the temperature of a certain measuring point on the surface to be measured by using the temperature measuring instrument to obtain a temperature measuring value;

providing a camera, and simultaneously acquiring an image of the surface to be measured by using the camera;

processing the acquired image to obtain a gray value of the measuring point;

obtaining a corresponding relation between the temperature measurement value and the gray value; and

and acquiring an image of the measuring point at a certain moment, and obtaining a temperature measuring value of the measuring point at the moment by using the corresponding relation.

Further, obtaining a corresponding relationship between the temperature measurement value and the gray value includes the steps of: in the process of continuously heating or continuously cooling the surface to be measured, acquiring temperature measurement values and corresponding gray values of a group of measurement points at fixed time intervals; and establishing a corresponding relation between the temperature measurement values and the corresponding gray values according to the multiple groups of temperature measurement values and the corresponding gray values.

Preferably, the temperature measurement value and the corresponding gray value have a linear relationship.

Further, the processing of the acquired image includes a step of extracting a color feature value of the measurement point in the image, the color feature value being a red R value.

Furthermore, in the step of extracting the color feature value of the measurement point in the image, the R channel pixel of the image is extracted as a gray scale image, and the gray scale value of the measurement point in the gray scale image is obtained.

Preferably, in the step of extracting the color feature value of the measurement point in the image, the R channel pixel of the image is extracted to form a gray image, and an average value of gray values of the measurement point and its surrounding pixels in the gray image is obtained.

Further, before processing the acquired image and extracting the color characteristic value of the measuring point in the image, the method also comprises the step of smoothing and filtering the image.

Further, before the temperature measurement value of the measurement point is obtained by using the corresponding relation, a step of extracting a color characteristic value from the obtained image of the measurement point is included.

Preferably, the temperature measuring instrument is provided with a laser indicator, and when the temperature measuring instrument is used for measuring the temperature of the measuring point, the laser indicator emits laser to indicate the position of the measuring point.

The invention has the beneficial effects that: the temperature measuring method of the invention establishes corresponding relations between the temperature values measured at different time points and the image gray values in the continuous heating or cooling process of a certain measuring point, then the thermometer can be removed, and the image gray values at a certain moment of the measuring point are substituted into the corresponding relations, thus the temperature value at the moment can be calculated. When the temperature of the measuring point in another furnace platform needs to be measured, the corresponding relation between the temperature value and the gray scale of the measuring point is reestablished, and the corresponding relation can be used for measuring and calculating the temperature of the measuring point. Therefore, it is not necessary to provide a dedicated temperature measuring instrument for each furnace stage. A large amount of equipment cost can be saved. In addition, the temperature of the measuring point is measured according to the image of the measuring point, the measuring distance interference is avoided, the measuring range is only a small-range area around the measuring point, the response is sensitive, the measuring error is small, and the measuring precision is improved.

Drawings

FIG. 1 is a flow chart of a temperature measurement method of the present invention;

fig. 2 is a graph showing a correspondence relationship between a measured temperature value and a gray-scale value at a certain measurement point according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, the temperature measuring method provided by the present invention includes the following steps:

firstly, providing a temperature measuring instrument, and measuring the temperature of a certain measuring point on the surface of an object to be measured by using the temperature measuring instrument to obtain a temperature measuring value.

In this embodiment, the surface of the object to be measured is a melt surface in a czochralski crystal growing furnace. The thermometer can be an infrared thermometer. The thermometer has a laser pointer. When the temperature measuring instrument is used for measuring the temperature of a certain point, the laser indicator emits laser to indicate the position of the point.

And optionally selecting a certain point of the surface to be measured as a measuring point, aligning the measuring point of the surface to be measured by using a temperature measuring instrument, and obtaining and outputting a temperature measuring value by using the temperature measuring instrument.

And secondly, providing a camera, and acquiring an image of the surface to be measured at the temperature measuring time point by using the camera.

The camera can be a CCD camera, and the measurement precision with high resolution ratio is good. The camera is aligned to the surface to be measured, and an image of the surface to be measured is obtained. Specifically, pixel points of the measuring points in the image of the surface to be measured are obtained.

And thirdly, processing the acquired image to obtain the gray value of the measuring point.

In this embodiment, processing the acquired image is mainly completed in the industrial personal computer, and the image processing program of the industrial personal computer processes the image, which may be implemented in the following steps:

first, the image is smoothly filtered to eliminate image noise interference. In this example, the average value is smoothly filtered.

Then, color feature values of the measurement points in the image are extracted. In this embodiment, the extracted color feature value is a red R value. Specifically, R-channel pixels of an image are extracted to form a grayscale image, and then a grayscale value is acquired from the grayscale image. When the gray value is obtained from the gray image, the gray value of the measuring point can be directly obtained. In this embodiment, the average value of the gray values of the measurement point and the surrounding pixels is obtained. Therefore, noise interference can be further removed, and the gray value closer to the actual image can be obtained.

And fourthly, obtaining the corresponding relation between the temperature measurement value and the gray value.

Specifically, in the process of continuously heating or continuously cooling the melt, the first step to the third step are repeated at regular intervals, so that a group of temperature measurement values and corresponding gray values can be obtained. And when the thermometer is used for measuring the temperature value of the measuring point, the acquired image of the surface to be measured is a group of temperature measuring values corresponding to the relationship and the image of the surface to be measured. And extracting the gray value of the measuring point in the image of the surface to be measured, namely the gray value corresponding to the temperature measuring value.

And establishing a corresponding relation between the temperature measurement values and the corresponding gray values according to the multiple groups of temperature measurement values and the corresponding gray values.

In this embodiment, in a time period of the continuous temperature rise or continuous temperature fall of the melt, for example, about 3 hours, a plurality of sets of temperature measurement values and corresponding gray values of a certain fixed measurement point are obtained at a certain frequency, for example, at a frequency of 10 minutes each time, which is specifically shown in table 1:

TABLE 1 correspondence table of temperature values and corresponding gray values of certain measuring points

Fitting the data in table 1 results in the linear equation y =5.0709x +1105.3, i.e. the map as shown in fig. 2.

And fifthly, acquiring an image of the measuring point, and obtaining the temperature measuring value of the measuring point by utilizing the corresponding relation.

For example, in the single crystal furnace, at a certain time of temperature increase or decrease, a certain measurement point is imaged, after image processing substantially the same as that in the third step, the gray value of the measurement point is obtained as 63, and x =63 is substituted into the linear equation obtained in the fourth step, so that the measured temperature y of the measurement point is obtained as 1424.8 ℃.

The temperature measuring method provided by the invention aims at the same furnace platform, and after the corresponding relation is obtained, the temperature measuring instrument can be removed, and the gray value of the measuring point is substituted into the corresponding relation, so that the temperature measuring value can be calculated. When the temperature of the measuring point in another furnace platform needs to be measured, the corresponding relation between the temperature value and the gray scale of the measuring point is reestablished, and the corresponding relation can be used for measuring and calculating the temperature of the measuring point. Therefore, it is not necessary to provide a dedicated temperature measuring instrument for each furnace stage. A large amount of equipment cost can be saved. In addition, the method measures the temperature of the measuring point according to the image of the measuring point, has no measuring distance interference, has a measuring range which is only a small range area around the measuring point, is sensitive in response and small in measuring error, and is beneficial to improving the measuring precision. It can be understood that the temperature measuring method of the invention is not only limited to the application in the technical field of Czochralski single crystal pulling, but also can be applied in other technical fields which have special pressure or atmosphere requirements and are inconvenient for directly measuring the temperature.