CN115685369A - Method and device for detecting solid or liquid deposits on the surface of a transparent plate - Google Patents

Abstract

The invention provides a method and a device for detecting solid or liquid attachments on the surface of a transparent plate, wherein the method comprises the following steps: the LED array light source is subjected to on-off control, and output in different coding modes is realized; light rays emitted by the LED array light source are received by the photoelectric detector after being totally reflected by the transparent plate; carrying out single-pixel imaging processing on a signal received by the photoelectric detector so as to realize the detection of solid or liquid attachments; the single-pixel imaging processing method comprises the following steps: recording the image of the attachment as an O matrix, wherein the coding mode is a P matrix, the signal detected and recorded by the photoelectric detector is an S matrix, and the PO = S is obtained by solving the coding matrix P and the signal matrix S to obtain the image O matrix of the attachment; imaging by using an image O matrix of the attachment, and judging the size and the position of the attachment according to the distribution condition of bright and dark points in the imaged image; and refreshing the imaged image by taking the t time interval as a period, and acquiring the dynamic distribution condition of the attachments.

Description

Method and device for detecting solid or liquid deposits on the surface of a transparent plate

technical field

The invention belongs to the field of sensors, and in particular relates to a method and a device for detecting solid or liquid attachments on the surface of a transparent plate.

Background technique

The solid-liquid detection device, taking the optical rain sensor as an example, the rain sensor detects the amount of water on the front windshield of the vehicle, automatically controls the wiper, keeps the glass clean, enhances visibility, ensures the driver to concentrate on driving, reduces the hidden danger of accidents, and increases the risk of driving. comfort. Rainfall composite sensors can be divided into four categories: flow type, piezoelectric vibrator type, capacitive type, and scattering type from the technical principle. Scattering rain detection is a method that uses optical non-contact detection. It has the characteristics of obvious changes in light intensity caused by rainfall, mature photoelectric conversion technology, and is not easily affected by electromagnetic interference. It is installed in the car and is not affected by the working environment. The mainstream technology used in rain sensors.

The structure of the current diffuse rain sensor generally uses the light emitted by the light-emitting diode to be adjusted by the lens system, and then shines on the windshield in a parallel light state; when the glass is dry, the light will be totally reflected and pass through the lens system to become a parallel light state Received by the receiving device, the maximum output is 100%. When there is rain or raindrops on the glass, due to the change of the refractive index, the light will not be fully reflected, but will be partially reflected depending on the size of the water droplet. At this time, the receiving tube only receives part of the light. Signal, the amount of rainfall can be calculated according to the percentage ratio. This method has the characteristics of obvious changes in light intensity caused by rainfall, mature photoelectric conversion technology, and is not easily affected by electromagnetic interference, but it is also easy to be interfered by background light, resulting in low signal-to-noise ratio, and multi-point detection requires multiple pairs of optical structures. lead to the disadvantage of complex structure.

For example, there is a blue light rain sensor for vehicles (CN201410471991.1) that integrates fog detection and rain detection. In order to solve the problems existing in the infrared scattering rain sensor, two optical channels are set, and a double reflection solution is adopted. The sensing area of each channel is increased. The performance and reliability of the sensor have been improved, but it is still unable to solve the problems of low signal-to-noise ratio caused by background light interference, and the complex structure caused by the need for multiple pairs of optical structures for multi-point detection.

Contents of the invention

The object of the present invention is to provide a method and device for detecting solid or liquid attachments on the surface of a transparent plate to address the shortcomings of the prior art.

In order to achieve the above object, the technical solution adopted in the present invention is:

The first aspect of the present invention provides a method for detecting solid or liquid deposits on the surface of a transparent plate, comprising:

Switch control on the LED array light source to realize different encoding mode output;

The light emitted by the LED array light source is totally reflected by the transparent plate and then received by the photodetector;

Perform single-pixel imaging processing on the signal received by the photodetector to realize the detection of solid or liquid attachments;

The method of single-pixel imaging processing is:

The image of the attachment is recorded as an O matrix, the encoding mode is a P matrix, and the signal detected and recorded by the photodetector is an S matrix, then:

Among them, an image with N-pixel resolution can be obtained through M times of coding measurement calculation and reconstruction, and any row [P _m1 ... P _mN ] of the P matrix of the coding pattern is the one-dimensional form of the m-th coding pattern P _m , corresponding to The measured signal value of the photodetector is S _m ;

Obtain the image O matrix of the attachment by solving the encoding matrix P and the signal matrix S;

Using the O-matrix image of the attachment, the size and position of the attachment can be judged according to the distribution of bright and dark spots in the imaged image, where the bright spot represents the transparent plate and the dark point represents the attachment;

Refresh the imaged image at intervals of t to obtain the dynamic distribution of attachments.

The second aspect of the present invention provides a solid-liquid detection device, including: a detection optical path part and a data processing part;

The detection light path part includes:

LED array, used as a light source, arranged in a mathematical array;

The first lens is arranged between the LED array and the transparent plate, and is used to map the light of the LED array to the surface of the transparent plate;

The second lens is arranged between the transparent plate and the photodetector, and is used for converging the light totally reflected by the transparent plate on the photodetector;

a photodetector, arranged behind the second lens, for collecting the light energy gathered by the second lens;

The data processing section includes:

The signal acquisition and processing circuit board is used for signal processing the signal of the photodetector;

The main controller is used to complete the method for detecting solid or liquid attachments on the surface of the transparent plate; it is electrically connected to the signal acquisition and processing circuit board to receive the signal-processed photodetector signal; it is connected to the LED array for control, To control the different switching modes of the LED array through the coding algorithm.

Compared with the prior art, the present invention has outstanding substantive features and significant progress, specifically:

1. The invention is based on the principle of total reflection of light, combined with a single-pixel imaging algorithm, to realize the detection of solid-liquid media;

2. The LED array used in the present invention has two functions of light source illumination and mode coding, and a single photoelectric receiver receives the light intensity of multiple light sources, which has the characteristics of high signal-to-noise ratio;

3. The optical structure designed by the present invention only needs two lenses, and has the characteristics of simple optical structure, small volume, easy miniaturization and high integration;

4. The imaging adopted in the design of the present invention is the Hadamard imaging algorithm, which eliminates the interference of common mode noise and has the characteristics of anti-environmental light interference.

Description of drawings

Fig. 1 is a raindrop size experiment and imaging result figure in the method of the present invention.

Fig. 2 is a schematic structural view of the detection optical path of the solid-liquid detection device of the present invention.

Detailed ways

The technical solutions of the present invention will be described in further detail below through specific implementation methods.

Example 1

This embodiment provides a method for detecting solid or liquid attachments on the surface of a transparent plate, including:

Switch control of the LED array light source to realize output in different coding modes; specifically, the Hadamard matrix can be used as the coding matrix to switch and control the LED array to realize output in different coding modes;

The light emitted by the LED array light source is totally reflected by the transparent plate and then received by the photodetector;

Perform single-pixel imaging processing on the signal received by the photodetector to realize the detection of solid or liquid attachments;

The method of single-pixel imaging processing is:

The image of the attachment is recorded as an O matrix, the encoding mode is a P matrix, and the signal detected and recorded by the photodetector is an S matrix, then:

Among them, an image with N-pixel resolution can be obtained through M times of coding measurement calculation and reconstruction, and any row [P _m1 ... P _mN ] of the P matrix of the coding pattern is the one-dimensional form of the m-th coding pattern P _m , corresponding to The measured signal value of the photodetector is S _m ;

Obtain the image O matrix of the attachment by solving the encoding matrix P and the signal matrix S;

Using the O-matrix image of the attachment, the size and position of the attachment can be judged according to the distribution of bright and dark spots in the imaged image, where the bright spot represents the transparent plate and the dark point represents the attachment;

Refresh the imaged image at intervals of t to obtain the dynamic distribution of attachments.

In this embodiment, the transparent plate is a light-permeable material plate, such as transparent glass, PMMA plate and the like.

Attachments are solid or liquid attachments whose refractive index is different from that of the transparent plate, such as dust, raindrops, water mist, etc.

The LED array light source is a red LED array light source or a blue LED array light source.

Taking the detection of raindrops on the windshield of an automobile as an example, the realization principle of the present invention is illustrated:

As shown in Figure 1, after the LED array light source is coded, the image point of each point light source of the LED array light source is projected to different positions of the windshield through lens coupling. Under the condition of no rain, according to the characteristics of total reflection, the light will be collected by the lens to the photodetector, and the distribution of the image of the LED array on the windshield can be realized through algorithm restoration. Under the condition of rain, because the condition of total reflection is destroyed, the light is transmitted out, and after the image of the LED array is restored, the corresponding position of the image will be black, and it can be judged that there are raindrops in the corresponding position. The size of the area where the raindrops fall on the surface of the windshield will cover the image points of the LED lights, and the corresponding points will be transmitted and cannot reach the photodetector, so as to detect the size of the raindrops and the number of raindrops at different positions. At the same time, with the imaging refresh, it can detect the distribution of raindrops in different time periods, and then obtain the three-dimensional information (x, y, t) of raindrops, so as to realize the real-time detection of the dynamic distribution of raindrops and help evaluate the rain at different times.

Example 2

As shown in Figure 2, this embodiment provides a solid-liquid detection device, including: a detection optical path part and a data processing part;

The detection light path part includes:

LED array, used as light source 1, arranged in a mathematical array;

The first lens 2 is arranged between the LED array and the transparent plate 3, and is used to map the light of the LED array to the surface of the transparent plate;

The second lens 4 is arranged between the transparent plate 3 and the photodetector 5 for converging the light totally reflected by the transparent plate 3 on the photodetector;

A photodetector 5, arranged behind the second lens 4, for collecting light energy gathered by the second lens;

The data processing section includes:

The signal acquisition and processing circuit board is used for signal processing the signal of the photodetector;

The main controller is used to complete the method for detecting solid or liquid attachments on the surface of the transparent plate described in embodiment 1; the electrical connection signal acquisition and processing circuit board is used to receive the photodetector signal after signal processing; the control connection LED array to control different switching modes of LED array through coding algorithm.

In this embodiment, the photodetector is a barrel-shaped detector with a single detection surface.

In actual implementation, the detection optical path part and the data processing part can be accommodated in a casing, and then a fixing member, such as a magnetic attraction device, is designed outside the casing to fix the solid-liquid detection device on the transparent plate.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications to the specific implementation of the invention or equivalent replacement of some technical features; without departing from the spirit of the technical solution of the present invention, should be included in the scope of the technical solution claimed in the present invention.

Claims (7)

1. A method for detecting solid or liquid deposits on the surface of a transparent plate, comprising:

the LED array light source is subjected to on-off control, and output in different coding modes is realized;

light rays emitted by the LED array light source are received by the photoelectric detector after being totally reflected by the transparent plate;

carrying out single-pixel imaging processing on a signal received by the photoelectric detector so as to realize the detection of solid or liquid attachments;

the single-pixel imaging processing method comprises the following steps:

when the image of the attached matter is recorded as an O matrix, the coding mode is a P matrix, and the signal detected and recorded by the photoelectric detector is an S matrix, the method comprises the following steps:

wherein, an image with N pixel resolution is obtained through M times of encoding measurement calculation reconstruction, and any row [ P ] of P matrix of encoding mode _m1 … P _mN ]Is the m-th coding pattern P _m In the one-dimensional form of (1), the corresponding measurement signal value of the photodetector is S _m ；

Solving through the coding matrix P and the signal matrix S to obtain an image O matrix of the attachment;

imaging by using an image O matrix of the attachment, and judging the size and the position of the attachment according to the distribution condition of bright and dark spots in the imaged image, wherein the bright spots represent a transparent plate, and the dark spots represent the attachment;

and refreshing the imaged image by taking the t time interval as a period, and acquiring the dynamic distribution condition of the attachments.

2. The method of claim 1, wherein the Hadamard matrix is used as a coding matrix to switch the LED array, so as to output different coding modes.

3. The method for detecting solid or liquid attachments on the surface of a transparent plate according to claim 1, characterized in that: the transparent plate is a transparent material plate.

4. The method for detecting solid or liquid attachments on the surface of a transparent plate according to claim 1, characterized in that: the adhesive substance is a solid or liquid adhesive substance having a refractive index different from that of the transparent plate.

5. The method for detecting solid or liquid attachments on the surface of a transparent plate according to claim 1, characterized in that: the LED array light source is a red LED array light source or a blue LED array light source.

6. A solid-liquid detecting apparatus, characterized by comprising: a detection light path part and a data processing part;

the detection light path part comprises:

the LED array is used as a light source and is arranged in a mathematical array mode;

a first lens disposed between the LED array and the transparent plate to map light of the LED array to a surface of the transparent plate;

the second lens is arranged between the transparent plate and the photoelectric detector and used for converging the light totally reflected by the transparent plate to the photoelectric detector;

the photoelectric detector is arranged behind the second lens and used for collecting the light energy converged by the second lens;

the data processing section includes:

the signal acquisition and processing circuit board is used for processing the signal of the photoelectric detector;

a main controller for performing the method for detecting solid or liquid attached matter on the surface of the transparent plate according to any one of claims 1 to 5; the signal acquisition and processing circuit board is electrically connected to receive the signal of the photoelectric detector after signal processing; the control is connected with the LED array to control different switch modes of the LED array through a coding algorithm.

7. The solid-liquid detecting apparatus according to claim 6, characterized in that: the photoelectric detector is a barrel-shaped detector with a single detection surface.

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