Projection type liquid level meter

Abstract

The invention relates to a projection type liquid level meter which comprises a measuring container. The parallel light source module is arranged above the measuring container and comprises a fixed light source, a dodging film and a collimating element which are arranged from top to bottom; light emitted by the fixed light source forms parallel light beams after passing through the dodging film and the collimating element, and the parallel light beams are projected to the liquid level of liquid in the measuring container at a fixed angle to form light spots; the image sensor is arranged on one side of the parallel light source module and is used for acquiring a light spot image on the liquid level of the liquid in the measuring container; the data processing unit is in signal connection with the image sensor and is used for receiving the light spot image, obtaining the light spot diameter and calculating the liquid level height of the liquid in the measuring container based on the light spot diameter; the data processing unit is further connected with a liquid level display screen, and the data processing unit transmits the calculated liquid level height to the liquid level display screen to be displayed. The liquid level height is ingeniously calculated through the light spot diameter, and the liquid level height is stably and accurately measured.

Description

TECHNICAL FIELD

[0001] The present application relates to a projection type liquid level meter, belonging to the technical field of liquid level meters. BACKGROUND

[0002] The liquid level meter is a key equipment for measuring the liquid level height in various containers in a thermal power plant, and plays an important role in the accurate measurement of water level and liquid level in the steam-water system and chemical system.

[0003] In a thermal power plant, a radar type liquid level meter is commonly used. The radar type liquid level meter calculates the liquid level height according to the time difference of the echo by emitting radar waves to the measured liquid surface. However, in the complex use environment of the thermal power plant, sometimes the propagation of radar waves is interfered by steam and dust, which can cause inaccurate measurement and make it difficult to accurately obtain liquid level data. SUMMARY

[0004] The purpose of the present application is to provide a projection type liquid level meter to solve the problems raised in the background.

[0005] The technical scheme of the present application is as follows: A projection type liquid level meter comprises a measuring container, and further comprises: A parallel light source module is arranged above the measuring container and comprises a fixed light source, a light homogenizing film and a collimating element arranged in sequence from top to bottom; the light emitted by the fixed light source is homogenized by the light homogenizing film and then shaped into a parallel light beam by the collimating element, and the parallel light beam is projected onto the liquid surface of the liquid in the measuring container at a fixed angle to form a light spot; An image sensor is arranged on one side of the parallel light source module and is used to collect the light spot image on the liquid surface of the liquid in the measuring container; A data processing unit is connected in signal with the image sensor and is used to receive the light spot image, derive the light spot diameter through image analysis algorithm and calculate the liquid level height of the liquid in the measuring container based on the light spot diameter; the data processing unit is further connected with a liquid level display screen, and the calculated liquid level height is transmitted to the liquid level display screen for display by the liquid level display screen.

[0006] Further, the data processing unit further comprises an audible and visual alarm, and the data processing unit is pre-set with a liquid level height threshold value; when the calculated liquid level height data exceeds the pre-set threshold value, the audible and visual alarm gives an alarm.

[0007] Further, a light shield is arranged below the parallel light source module, the light shield is in a cylindrical structure and extends downward to the upper surface of the measuring container, the width of the light shield is equal to the width of the measuring container, and the light path of the parallel light beam and the upper surface of the measuring container are covered in the light shield.

[0008] Further, the light shield is detachably connected above the measuring container through a buckle structure.

[0009] Furthermore, the formula for calculating the liquid level height h is: ; Where α is the fixed emission direction angle of the parallel beam emitted from the parallel light source module, H is the vertical distance from the parallel beam to the bottom of the measuring container, and L is the aperture of the collimating element.

[0010] The present invention has the following beneficial effects: This invention uses a flat light source module to generate a stable projection light spot, an image sensor to accurately acquire the light spot image, and a data processing unit to process the light spot image and calculate the liquid level height in the container. It cleverly calculates the liquid level height through the light spot diameter, thus achieving stable and accurate measurement of the liquid level height. By using a light-diffusing film and a collimating element, a parallel light beam is generated. At the same time, the use of a light shield prevents external ambient light from affecting the transmission of the parallel light beam, thereby improving the measurement accuracy of the level gauge. Attached Figure Description

[0011] Fig. 1 Schematic diagram of the invention; Fig. 2 This is a schematic diagram of the optical path structure of the present invention.

[0012] The reference numerals in the figure are as follows: 1. Parallel light source module; 11. Fixed light source; 12. Light-diffusing film; 13. Collimating element; 2. Measuring container; 3. Image sensor; 4. Data processing unit; 5. Liquid level display screen; 6. Light shield. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0014] like Figs. 1-2 As shown, a projection-type liquid level gauge includes: Measuring container 2 is used to hold liquid.

[0015] The parallel light source module 1 is positioned above the measuring container 2. It includes a fixed light source 11, a light-diffusing film 12, and a collimating element 13 arranged sequentially from bottom to top. The light emitted by the fixed light source 11 is homogenized by the light-diffusing film 12 and then shaped into a parallel beam by the collimating element 13. The parallel beam is projected onto the surface of the liquid in the measuring container 2 at a fixed angle, making the exit angle of the parallel beam a fixed angle and forming a light spot image. A light shield 6 is positioned below the parallel light source module 1. The parallel light source module 1 is located at the center of the upper surface of the light shield 6. The lower end of the light shield 6 is detachably connected to the upper surface of the measuring container 2 through a snap-fit ​​structure. The light shield 6 extends downward in a cylindrical structure, covering the light path of the parallel beam and the upper surface of the measuring container 2. The width of the light shield 6 is equal to the width of the measuring container 2.

[0016] Image sensor 3 is located on one side of parallel light source module 1. The lens of image sensor 3 is directly facing the light spot formed by the parallel light beam inside the measurement container 2. The image sensor is used to capture the light spot position image and transmit the light spot position image to data processing unit 4. At the same time, the external ambient light is prevented from interfering with the image sensor 3 in acquiring the light spot image through the cooperation of light shield 6. Image sensor 3 adopts an image sensor with a resolution ≥1280*720 and a frame rate ≥30fps to achieve stable acquisition of light spot image, such as CCD image sensor and CMOS image sensor.

[0017] Data processing unit 4, connected to image sensor 3, receives and processes the spot image, obtains the spot diameter d from the spot image, and calculates the liquid level height in measuring container 2. The formula for calculating the liquid level height h can be derived from the formula for calculating the spot diameter d. , ; Where α is the fixed emission direction angle of the parallel beam emitted from the parallel light source module 1, H is the vertical distance from the parallel light source module 1 to the bottom of the measuring container 2, and L is the aperture of the collimating element 13.

[0018] The specific methods by which the data processing unit 4 obtains the diameter of the light spot from the light spot image include, but are not limited to: Second-order moment method: Based on the grayscale distribution of the spot image acquired by image sensor 3, the spot diameter is calculated according to the second-order moment method specified in ISO 11146 standard; Edge fitting method: Extract the edge points of the spot image and fit a circle using the least squares method. Use the radius of the fitted circle as the spot radius to calculate the spot diameter.

[0019] The above method is a common means of calculating the spot diameter. Those skilled in the art can choose the above method or use other equivalent methods according to the characteristics of the spot. Changes in liquid level may cause the spot image captured by the image sensor to shift, resulting in measurement error. Compensation and correction for measurement error are well-known technologies in the field. Existing algorithms can be used to compensate and correct the error, thereby ensuring the accuracy of spot diameter calculation.

[0020] The data processing unit 4 also includes an audible and visual alarm. The data processing unit 4 has a preset liquid level height threshold. When the calculated liquid level height exceeds the preset threshold, the audible and visual alarm will issue an alarm signal to remind the staff. The data processing unit 4 is also connected to a liquid level display screen 5 to display the liquid level height data.

[0021] The working principle of this invention is as follows: Light is emitted by a fixed light source 11. The emitted light is shaped into a parallel beam by a light-diffusing film 12 and a collimating element 13. The parallel beam is projected onto the surface of the liquid in the measuring container 2. The image sensor 3 captures the image of the light spot on the surface of the liquid in the measuring container 2 and transmits it to the data processing unit 4 to process and obtain the diameter of the light spot. The data processing unit 4 calculates the liquid level height in the measuring container 2 according to the corresponding calculation formula and displays it on the liquid level display screen 5. When the liquid level calculated by the data processing unit 4 is higher than the preset threshold, the audible and visual alarm will issue an alarm signal to remind the staff to take action.

[0022] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A projection type liquid level gauge comprising a measuring vessel, characterized in that, Also include: Parallel light source module, disposed above the measuring container, including fixed light source, light uniformity film and collimating element arranged in turn from top to bottom; the light emitted by the fixed light source is homogenized by the light uniformity film and then shaped into parallel light beam by the collimating element, the parallel light beam is projected onto the liquid surface in the measuring container at a fixed angle to form a light spot; Image sensor, disposed on one side of the parallel light source module, for collecting the light spot image on the liquid surface in the measuring container; Data processing unit, signal connected with the image sensor, for receiving the light spot image, obtaining the light spot diameter through image analysis algorithm, and calculating the liquid level height in the measuring container based on the light spot diameter; the data processing unit is also connected with the liquid level display screen, and the calculated liquid level height is transmitted to the liquid level display screen by the data processing unit for display by the liquid level display screen.

2. A projection type liquid level gauge as claimed in claim 1, characterized in that: The data processing unit also includes an audible and visual alarm, and the data processing unit is pre-set with a liquid level height threshold value, when the calculated liquid level height data exceeds the pre-set threshold value, the audible and visual alarm gives an alarm.

3. A projection type liquid level gauge as claimed in claim 1, wherein: The lower side of the parallel light source module is provided with a light shield, which is a cylindrical structure extending downward to the upper surface of the measuring container, the width of the light shield is equal to the width of the measuring container, and the light path of the parallel light beam and the upper surface of the measuring container are covered.

4. A projection type liquid level gauge as claimed in claim 3, wherein: The light shield is detachably connected above the measuring container through a buckle structure.

5. A projection type liquid level gauge as claimed in claim 1, wherein: The liquid level height h calculation formula is: ； Wherein α is the fixed emission direction angle of the parallel light beam emitted from the parallel light source module, H is the vertical distance from the parallel light beam to the bottom of the measuring container, and L is the light aperture of the collimating element.

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