Pressure sensor based on corrugated diaphragm and detection method thereof

Abstract

The invention discloses a pressure sensor based on a corrugated diaphragm and a detection method thereof. The pressure sensor comprises a dot matrix and a data processing module. The dot matrix is located outside the corrugated diaphragm, the dot matrix comprises at least two microwave points, different microwave points face different positions of the corrugated diaphragm, the distance between each microwave point and the corresponding position of the corrugated diaphragm is different, and each microwave point is electrically connected with the data processing module. The pressure, the stress position of the corrugated diaphragm and the flow of the corrugated diaphragm under the action of the pressure can be determined. The application scene of the pressure sensor is broadened, so that the pressure sensor can adapt to application under various requirements in a complex environment and is not easily interfered by the outside.

Description

Technical Field

[0001] The invention belongs to the field of pressure detection, and relates to a pressure sensor based on a corrugated diaphragm and a detection method thereof. Background Art

[0002] The corrugated diaphragm is a diaphragm with good elasticity and pressure resistance. It has a wide range of applications in the engineering field, such as pumps and valves, automotive industry, pneumatic components, gas equipment, electronics industry, electrical equipment, pneumatic and hydraulic equipment, etc. Its main functions are sealing, adjusting gaps, etc. In addition, the corrugated diaphragm is also commonly used in valves, regulating valves, automatic mechanical followers, switches and counters for flow, pressure, differential, liquid level, constant temperature volume thermal compensation, etc. The corrugated diaphragm is usually a circular diaphragm with concentric rings. It is a pressure sensitive element that can move in a direction perpendicular to its flexibility. It can separate two media with unequal pressures and has flexibility. According to different profiles, the corrugated diaphragm is often divided into arc, sine, triangle, trapezoidal, etc. The corrugated diaphragm refers to a diaphragm that, when subjected to pressure or force, moves toward the side with low pressure, causing its center to produce a displacement that is related to the pressure difference. The corrugated diaphragm can be made of a variety of materials, such as stainless steel, rubber, etc. Among them, the rubber corrugated diaphragm has better elasticity and sealing, while the stainless steel corrugated diaphragm has higher strength and corrosion resistance. The characteristics of the corrugated diaphragm are generally characterized by the relationship between the displacement of the center and the measured pressure.

[0003] The existing corrugated diaphragm pressure sensor usually produces deformation and displacement changes under the action of external pressure, and the capacitance between the corrugated diaphragm and the electrode fixed on the sensor changes, thereby outputting a corresponding analog signal to realize the conversion of physical quantity into electrical analog quantity. However, the traditional corrugated diaphragm pressure sensor can only measure the pressure through the change of capacitance, and cannot determine the specific force position, and is easily disturbed by the external environment. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a pressure sensor based on a corrugated diaphragm and a detection method thereof, which can determine the specific force position of the corrugated diaphragm.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A pressure sensor based on a corrugated diaphragm, comprising a dot matrix and a data processing module; The dot matrix is ​​located outside the corrugated diaphragm, and includes at least two microwave points. Different microwave points face different positions of the corrugated diaphragm, and the distance between each microwave point and the corresponding position of the corrugated diaphragm is different. Each microwave point is electrically connected to the data processing module.

[0006] Preferably, the wavelength band of each microwave point is different.

[0007] Preferably, a shell is provided outside the dot matrix and the data processing module.

[0008] Preferably, the housing is a Faraday cage.

[0009] Preferably, the data processing module adopts MCU.

[0010] A detection method of the pressure sensor based on the corrugated diaphragm comprises the following process: When the pressure sensor is not acted upon by a force, the microwave point sends a microwave signal to the corrugated diaphragm, and the microwave point receives the microwave signal reflected from the corrugated diaphragm, and calculates the distance between each microwave point and the corresponding position of the corrugated diaphragm as the equilibrium distance; After the pressure sensor is acted upon by force, the microwave point sends a microwave signal to the corrugated diaphragm, and the microwave point receives the microwave signal fed back by the corrugated diaphragm when it is under pressure, and calculates the distance between each microwave point and the corresponding position of the corrugated diaphragm as the force distance; The equilibrium distance and force distance of each microwave point are compared. When the equilibrium distance is inconsistent with the force distance, the position on the corrugated diaphragm corresponding to the current microwave point is under pressure. When the equilibrium distance is consistent with the force distance, the position on the corrugated diaphragm corresponding to the current microwave point is not under pressure.

[0011] Preferably, the distance calculation process between the microwave point and the corresponding position of the corrugated diaphragm is as follows: respectively record the time interval between the signal sent from the microwave point to the corrugated diaphragm and the time interval between the signal reflected from the corrugated diaphragm to the microwave point , according to the formula s=c , where s is the distance traveled by the microwave between the microwave point and the corrugated diaphragm, and c is the microwave speed, then the distance between the microwave point and the corrugated diaphragm is s / 2.

[0012] Preferably, the pressure at the position of the corrugated diaphragm corresponding to the current microwave point is calculated based on the difference between the equilibrium distance and the force distance.

[0013] Furthermore, the flow rate between the two microwave points is calculated based on the pressure difference between the two microwave points.

[0014] Going further, the flow rate is calculated according to the formula Q= It is calculated, where Q is the flow rate, F1-F2 is the pressure difference between the two microwave points, P is the resistance coefficient of the corrugated diaphragm, and S is the cross-sectional area of ​​the corrugated diaphragm.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention is provided with a corrugated diaphragm, a dot matrix composed of at least two microwave points, and a data processing module. When the pressure sensor is subjected to pressure, the microwave point sends a signal to the corrugated diaphragm, and then receives the reflected signal sent by the corrugated diaphragm, so as to obtain the distance between the corresponding position of the microwave point and the corrugated diaphragm. The data processing module processes the signal received by the microwave point when it is not subjected to force and when it is subjected to pressure, and determines the force position of the corrugated diaphragm according to whether the distance is consistent when it is not subjected to force and when it is subjected to pressure. The use scenarios of the pressure sensor are broadened, so that it can adapt to the application under various requirements in complex environments and is not easily affected by external interference.

[0016] Furthermore, the housing is used to shield external signal interference and protect the pressure sensor from external damage.

[0017] Furthermore, by sending a signal from the microwave point to the corrugated diaphragm and then receiving a reflected signal sent by the corrugated diaphragm, the distance between the microwave point and the corrugated diaphragm can be obtained, thereby determining the pressure.

[0018] Furthermore, the flow rate of the corrugated diaphragm when it is subjected to pressure can be calculated based on the pressure magnitude and the force position. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a pressure sensor based on a corrugated diaphragm proposed in this application; The above drawings include the following reference numerals: 1-corrugated diaphragm, 2-MCU, 3-microwave point, 4-housing. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" used in this article includes any and all combinations of one or more related listed items. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0024] The present application provides a pressure sensor based on a corrugated diaphragm, which realizes the measurement of pressure, force position and flow rate by combining the reflection of microwave signals and the method of measuring time difference.

[0025] like Figure 1 As shown, the pressure sensor based on the corrugated diaphragm described in this embodiment mainly includes: a dot matrix, a data processing module, and a shell 4, wherein the dot matrix includes n microwave points 3, n is a positive integer greater than or equal to 2, and the number is not specifically limited in this application.

[0026] The data processing module is specifically MCU2 (Microcontroller Unit) in this application, which is not specifically limited in this application, and can also be a data processing module, a processor, etc. Among them, MCU2 is electrically connected to all microwave points 3, and the microwave points 3 can be controlled by MCU2. MCU2 includes a communication pin and a clock pin. The communication pin is specifically RS485 in this application, and can also be RS232, CAN bus, etc., which is not specifically limited in this application, and is used to transmit the processed data in MCU2. The clock pin can control the data output through timing.

[0027] A shell 4 is arranged outside the pressure sensor, wherein the shell 4 is specifically a Faraday cage for shielding external signal interference, and may also be a metal box, etc., which is not specifically limited in this application.

[0028] The microwave points 3 are arranged below the corrugated diaphragm 1. In this embodiment, the dot matrix includes four microwave points 3, specifically P1, P2, P3, and P4, which are used to send and receive signals.

[0029] According to the pressure sensor proposed in the embodiment of the present application, the specific principle includes: when the outside world exerts pressure on the pressure sensor, the corrugated diaphragm 1 will deform and act on the microwave point 3, at this time, the MCU2 is controlled to energize the microwave point 3, and the microwave point 3 sends a microwave signal to the corrugated diaphragm 1, and the microwave point 3 receives the pressure signal reflected from the corrugated diaphragm 1, and records the time interval between the signal sent by the microwave point 3 to the corrugated diaphragm 1 and the signal reflected from the corrugated diaphragm 1 to the microwave point 3 , microwave point 3 sends the current signal to MCU2, and MCU2 uses the formula s=c , where s is the distance traveled by the microwave between microwave point 3 and corrugated diaphragm 1, i.e., the process of microwaves going from microwave point 3 to corrugated diaphragm 1 and then returning to microwave point 3, and c is the microwave speed, which is roughly the same as the speed of light, which is 3*10 ^8 m / s, is the time interval, the total distance of microwave point 3 sending and receiving signals can be calculated, and the current distance is the shortest distance. Then the distance between microwave point 3 and corrugated diaphragm 1 is s / 2. Then the deformation of corrugated diaphragm 1 on microwave point 3 when subjected to pressure is - , S2 is the total distance after being subjected to pressure, and S1 is the total distance without being subjected to pressure, recorded as At this time, according to the formula F=E , where E is the elastic modulus of the corrugated diaphragm 1, the pressure at the position of the corrugated diaphragm 1 corresponding to the current microwave point 3 can be calculated.

[0030] In addition, when the pressure sensor is not subjected to force, the microwave point 3 sends a microwave signal to the corrugated diaphragm 1, and the microwave point 3 receives the microwave signal reflected from the corrugated diaphragm 1, calculates the current distance between each microwave point 3 and the corresponding position of the corrugated diaphragm 1, which is called the equilibrium distance, and sends the current distance information to the storage module of MCU2.

[0031] After the pressure sensor is acted upon by force, microwave point 3 sends microwave signals to corrugated diaphragm 1, and microwave point 3 receives microwave signals fed back by corrugated diaphragm 1 when under pressure, and calculates the current distance between each microwave point 3 and the corresponding position of corrugated diaphragm 1, which is called the force distance. Then the current distance information is sent to the storage module of MCU2.

[0032] In the embodiment of the present application, the wave band of each microwave point 3 is different, so after the microwave point 3P1 sends a signal, it can only receive the signal sent by the corrugated diaphragm 1 in the current frequency band, and so on. Therefore, MCU2 compares the balance distance and the force distance of each microwave point 3 according to the distance information of the storage module, and can determine at which point the distance change occurs, that is, when the balance distance is inconsistent with the force distance, the position on the corrugated diaphragm 1 corresponding to the current microwave point 3 is under pressure, and when the balance distance is consistent with the force distance, the position on the corrugated diaphragm 1 corresponding to the current microwave point 3 is not under pressure, and the microwave point 3 under pressure can be determined, and the combination of the current microwave points 3 is the force position of the corrugated diaphragm.

[0033] In addition, MCU2 calculates the force position and force magnitude of microwave point 3, for example, the pressure magnitudes F1 and F2 calculated from microwave point 3P1 and microwave point 3P2, and calculates the pressure magnitudes F1 and F2 according to the formula Q= , where Q is the flow rate, F1-F2 is the pressure difference between microwave point 3P1 and microwave point 3P2, P is the resistance coefficient of the corrugated diaphragm 1, S is the cross-sectional area of ​​the corrugated diaphragm 1, that is, the distance between microwave point 3P1 and microwave point 3P2, the flow rate between microwave point 3P1 and microwave point 3P2 of the pressure sensor can be calculated. By analogy, the overall continuous flow rate of the pressure sensor can be obtained.

[0034] MCU2 packages the calculated force magnitude, force position, flow rate and other data, and transmits them through RS485 pins. The clock pin can control the orderly output of data by simultaneously outputting clk.

[0035] Through the specific working principle of the above pressure sensor when it is under pressure, the pressure magnitude and force position of the current pressure sensor when it is under pressure can be calculated, and the flow rate of the current pressure sensor can be determined according to the force position, so that it can be adapted to more application scenarios. In addition, the current pressure sensor sends signals through microwaves and is not easily interfered by the external environment, thereby improving the measurement accuracy of the pressure sensor.

[0036] MCU2 (Microcontroller Unit) is an embedded microcomputer chip that integrates a processor, memory, and multiple input / output interfaces. It is usually used in applications such as automation control and data processing, and can control external hardware devices according to programs and perform complex logical operations.

[0037] In the application of the pressure sensor based on the corrugated diaphragm described in this embodiment, the main functions of MCU2 include: 1. Signal control: Through the electrical connection with the microwave dot matrix, MCU2 can control the power on and off of the microwave point 3, thereby controlling the sending and receiving of microwave signals.

[0038] 2. Data processing: MCU2 receives the signal from microwave point 3, calculates the distance from microwave point 3 to corrugated diaphragm 1 according to the time interval, and uses the formula to calculate the pressure, position, and flow.

[0039] 3. Storage and comparison: The storage module of MCU2 can record the equilibrium distance and force distance of microwave point 3, thereby realizing real-time comparison and pressure position detection.

[0040] 4. Communication transmission: MCU2 transmits data such as pressure, force position and flow to the host computer or other devices through communication pins (such as RS485 interface). Timing control is performed through the clock pin to ensure orderly data output.

[0041] 5. Anti-interference design: By placing MCU2 in the housing 4 of the Faraday cage structure, external electromagnetic interference is reduced and the accuracy of measurement is improved.

[0042] MCU2 serves as the core data processing and control unit in the pressure sensor system, enabling the sensor to perform precise pressure, position and flow monitoring.

[0043] The microwave point 3 is a key component of the pressure sensor, which is used to send and receive microwave signals to detect the displacement of the corrugated diaphragm 1 and calculate the force. The main functions and features of the microwave point 3 are as follows: 1. Signal sending and receiving: Each microwave point 3 can send a microwave signal to the corrugated diaphragm 1 and receive a signal reflected back from the corrugated diaphragm 1 .

[0044] By controlling the power-on state of the microwave spot 3, the MCU2 can send and receive signals at specific times.

[0045] 2. Measurement time interval: After sending the signal, the microwave point 3 will record the time interval Δt from sending to receiving the signal, reflecting the change in the distance between the microwave point 3 and the corrugated diaphragm 1.

[0046] By measuring the microwave point 3, the minute deformation of the corrugated diaphragm 1 can be calculated, and then the pressure can be deduced.

[0047] 3. Independent frequency band: Each microwave point 3 uses a different frequency band (for example, P1, P2, P3, and P4 use different microwave frequencies) to avoid signal interference.

[0048] This design ensures that each microwave point 3 can only receive reflected signals in its own frequency band, thereby accurately identifying pressure changes at different points.

[0049] 4. Position and flow measurement: When a plurality of microwave points 3 work simultaneously, the pressure difference at different positions of the corresponding corrugated diaphragm 1 can be measured.

[0050] The flow rate can be further calculated through the pressure difference between multiple points and the parameters of the corrugated diaphragm 1, thereby realizing flow rate monitoring inside the sensor.

[0051] 5. Force test: The microwave point 3 can accurately detect the distance difference between the corrugated diaphragm 1 under stress and under no stress, and by comparing it with the equilibrium distance (the distance when no stress) stored in MCU2, it can determine whether it is under pressure and the position of the pressure.

[0052] In the pressure sensor, the microwave point 3 measures the deformation of the corrugated diaphragm 1 by sending and receiving microwave signals, and combines the time interval and the characteristic parameters of the corrugated diaphragm 1 to achieve high-precision detection of the pressure size and distribution position.

[0053] The present invention is provided with a corrugated diaphragm 1, a dot matrix composed of at least two microwave points 3, and a data processing module. When the pressure sensor is subjected to pressure, the microwave point 3 sends a signal to the corrugated diaphragm 1, and then receives the reflected signal sent by the corrugated diaphragm 1, so as to obtain the distance between the microwave point 3 and the corrugated diaphragm 1, thereby determining the pressure. Then, the signal received by the microwave point 3 when it is not subjected to force and when it is subjected to pressure is processed by the data processing module to determine the force position of the corrugated diaphragm. At the same time, the flow rate of the corrugated diaphragm when it is subjected to pressure can be calculated according to the pressure size and the force position. Pressure measurement is performed through microwave signals, which has strong anti-interference ability and improves measurement accuracy. It can realize real-time monitoring of pressure and flow at multiple locations, and is suitable for complex application scenarios. This pressure sensor realizes accurate monitoring of force distribution and flow through the combination of microwaves and corrugated diaphragms, and can be used in various fields such as industrial pressure monitoring and fluid delivery systems. The use scenarios of the pressure sensor are broadened, so that it can adapt to applications under various requirements in complex environments and is not easily affected by external interference.

[0054] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0055] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0056] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0057] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0058] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

[0059] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A pressure sensor based on a corrugated diaphragm, characterized in that: Including dot matrix and data processing modules; The dot matrix is ​​located outside the corrugated diaphragm (1), the dot matrix comprises at least two microwave points (3), different microwave points (3) face different positions of the corrugated diaphragm (1), the distance between each microwave point (3) and the corresponding position of the corrugated diaphragm (1) is different, and each microwave point (3) is electrically connected to the data processing module.

2. The pressure sensor based on the corrugated diaphragm according to claim 1, characterized in that: The wavelength band of each microwave point (3) is different.

3. The pressure sensor based on the corrugated diaphragm according to claim 1, characterized in that: A shell (4) is arranged outside the dot matrix and the data processing module.

4. The pressure sensor based on the corrugated diaphragm according to claim 1, characterized in that: The housing (4) is a Faraday cage.

5. The pressure sensor based on the corrugated diaphragm according to claim 1, characterized in that: The data processing module uses MCU (2).

6. A detection method for a pressure sensor based on a corrugated diaphragm according to any one of claims 1 to 5, characterized in that: The process includes: When the pressure sensor is not acted upon by a force, the microwave point (3) sends a microwave signal to the corrugated diaphragm (1), the microwave point (3) receives the microwave signal reflected from the corrugated diaphragm (1), and calculates the current distance between each microwave point (3) and the corresponding position of the corrugated diaphragm (1) as a balance distance; After the pressure sensor is acted upon by a force, the microwave point (3) sends a microwave signal to the corrugated diaphragm (1), and the microwave point (3) receives the microwave signal fed back by the corrugated diaphragm (1) when the pressure is applied, and calculates the current distance between each microwave point (3) and the corresponding position of the corrugated diaphragm (1) as the force applied distance; The equilibrium distance and the force distance of each microwave point (3) are compared. When the equilibrium distance is inconsistent with the force distance, the position on the corrugated diaphragm (1) corresponding to the current microwave point (3) is subjected to pressure. When the equilibrium distance is consistent with the force distance, the position on the corrugated diaphragm (1) corresponding to the current microwave point (3) is not subjected to pressure.

7. The detection method of the pressure sensor based on the corrugated diaphragm according to claim 6, characterized in that: The distance calculation process between the microwave point (3) and the corresponding position of the corrugated diaphragm (1) is as follows: the time interval between the signal sent from the microwave point (3) to the corrugated diaphragm (1) and the time interval between the signal reflected from the corrugated diaphragm (1) to the microwave point (3) is recorded respectively. , according to the formula s=c , where s is the distance traveled by the microwave between the microwave point (3) and the corrugated diaphragm (1), and c is the microwave speed. Then, the distance between the microwave point (3) and the corrugated diaphragm (1) is s / 2.

8. The detection method of the pressure sensor based on the corrugated diaphragm according to claim 6, characterized in that: The magnitude of the pressure at the position of the corrugated diaphragm (1) corresponding to the current microwave point (3) is calculated based on the difference between the equilibrium distance and the force distance.

9. The detection method of the pressure sensor based on the corrugated diaphragm according to claim 8, characterized in that: The flow rate between the two microwave points (3) is calculated based on the pressure difference between the two microwave points (3).

10. The detection method of the pressure sensor based on the corrugated diaphragm according to claim 9, characterized in that: The flow rate is calculated according to the formula Q= The result is obtained by calculation, wherein Q is the flow rate, F1-F2 is the pressure difference between the two microwave points (3), P is the resistance coefficient of the corrugated diaphragm (1), and S is the cross-sectional area of ​​the corrugated diaphragm (1).

Images