Coffee maker and water level detection circuit

Abstract

The application relates to a coffee machine and a water level detection circuit. The water level detection circuit adopts two sensing pads, an oscillation excitation unit, a filtering and shaping unit and an amplifying unit. The liquid dielectric constant change of a target container is sensed through the two sensing pads to form a variable sensing capacitor. The oscillation excitation unit generates a high-frequency alternating current signal, and the corresponding high-frequency alternating current signal is loaded on the medium through the two sensing pads. The sensing capacitor converts the capacitor change signal generated by the liquid level change in the target container into an alternating voltage signal. The filtering and shaping unit converts the received alternating voltage signal into a direct current signal. The amplifying unit isolates and amplifies the direct current signal, and transmits the generated water level state signal to the corresponding main control unit. Through the application, the problems of water level detection failure and electrode corrosion of the coffee machine in the related art are solved.

Description

Technical Field

[0001] This application relates to the field of coffee machine component technology, and more particularly to a coffee machine and a water level detection circuit. Background Technology

[0002] In related technologies, coffee machines are becoming more and more common and intelligent. They can not only achieve the basic function of brewing coffee, but also have more user-friendly functions such as automatically setting the temperature and setting the amount of coffee to use. Moreover, in order to prevent coffee machines from burning dry or overflowing, current coffee machines are equipped with water level detection functions.

[0003] In related technologies, coffee machine water level detection methods include reed switch float detection and metal electrode detection. Reed switch float detection is currently the most widely used detection technology, which can achieve non-contact water level detection. Its principle is to embed a magnet in a float and place it in a container filled with water. The float moves up and down according to the water level, and the magnetic control switch detects the water level by the float's approach or departure. However, the reed switch float detection structure has the risk of the float getting stuck, which may cause the water level detection to fail, and it is costly. Metal electrode detection is widely used in hot water level detection. Its principle is to apply a voltage between two metal electrodes. The water level is detected by the difference in electrode voltage when the water touches the two metal electrodes. However, the metal electrode detection voltage is applied between the two electrodes for a long time. When exposed to a high temperature and humid environment for a long time, the metal electrodes are prone to corrosion and electrolysis.

[0004] Currently, no effective solutions have been proposed to address the issues of water level detection failure and electrode corrosion in coffee machines in related technologies. Utility Model Content

[0005] In view of this, it is necessary to provide a coffee machine and a water level detection circuit to at least solve the problems of easy failure of water level detection and easy corrosion of electrodes in related technologies.

[0006] In a first aspect, this application provides a technical solution as follows: a water level detection circuit for a coffee machine, comprising two sensing pads, an oscillation excitation unit, a filtering and shaping unit, and an amplification unit. The two sensing pads are mounted on the bottom of a target container and spaced apart. The oscillation excitation unit is electrically connected to the two sensing pads. One of the two sensing pads is electrically connected to the oscillation excitation unit and also electrically connected to the input terminal of the filtering and shaping unit. The output terminal of the filtering and shaping unit is electrically connected to the input terminal of the amplification unit. The output terminal of the amplification unit is coupled and electrically connected to the main control unit of the coffee machine. The sensing pads are used to form a sensing capacitance with the medium of the target container; the oscillation excitation unit is used to generate a high-frequency AC signal, and load the corresponding high-frequency AC signal onto the medium through the two sensing pads, and convert the capacitance change signal generated by the sensing capacitance according to the liquid level change in the target container into an AC voltage signal; the filtering and shaping unit is used to convert the received AC voltage signal into a DC signal; the amplification unit is used to isolate and amplify the DC signal, and transmit the generated water level status signal to the corresponding main control unit, wherein the water level status signal is used to characterize whether there is water in the target container.

[0007] Secondly, embodiments of this application also provide a coffee machine, including a plastic container, wherein a sensing probe is provided inside the plastic container and is electrically coupled to a water level detection circuit, the water level detection circuit being the water level detection circuit described in the first aspect, and the sensing probe being the sensing pad.

[0008] Compared with related technologies, this embodiment provides a coffee machine and a water level detection circuit. It employs two sensing pads, an oscillation excitation unit, a filtering and shaping unit, and an amplification unit. The two sensing pads sense changes in the dielectric constant of the liquid in the target container, forming a changing sensing capacitance. The oscillation excitation unit generates a high-frequency AC signal, which is then applied to the medium via the two sensing pads. The capacitance change signal generated by the sensing capacitance based on the liquid level change in the target container is converted into an AC voltage signal. The filtering and shaping unit converts the received AC voltage signal into a DC signal. The amplification unit isolates and amplifies the DC signal, and the generated water level status signal is transmitted to the corresponding main control unit. This allows for the construction of a water level detection circuit using simple components to detect whether a plastic container is short of water. This solves the problems of easy failure of water level detection and electrode corrosion in related technologies, achieving the beneficial effects of reducing design costs and improving the performance of the coffee machine.

[0009] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0011] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A structural block diagram of a water level detection circuit provided in an embodiment of this application; Figure 2 This is a topology diagram of the water level detection circuit provided in an embodiment of this application. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] The coffee machine and water level detection circuit of this application will be described below with reference to the accompanying drawings in the embodiments of this application and through specific embodiments.

[0015] refer to Figures 1 to 2 The water level detection circuit provided in this application embodiment, for use in a coffee machine, is characterized by comprising two sensing pads 100, an oscillation excitation unit 200, a filtering and shaping unit 300, and an amplification unit 400. The two sensing pads 100 are mounted on the bottom of the target container and spaced apart. The oscillation excitation unit 200 is electrically connected to the two sensing pads 100. One of the two sensing pads 100, at its connection point with the oscillation excitation unit 200, is also electrically connected to the input terminal of the filtering and shaping unit 300. The output terminal of the filtering and shaping unit 300 is electrically connected to the input terminal of the amplification unit 400. The output terminal of the amplification unit 400 is coupled and electrically connected to the main control unit of the coffee machine. Two sensing pads 100 are used to form a sensing capacitance with the medium of the target container.

[0016] In this embodiment, the equivalent capacitance is formed as follows: the sensing pads 100 serve as the two electrodes of the sensing capacitor, and their spacing, together with the wall thickness of the plastic container (≤5mm), constitutes the electrode spacing of the capacitor. The medium inside the container (air or water) is the dielectric layer of the capacitor. The dielectric constant of water (ε≈80) is much greater than that of air (ε≈1) and plastic (ε≈6~12). Therefore, when there is no water inside the plastic container, the medium between the two sensing pads 100 is air + plastic, and the equivalent capacitance C is... x Smaller; in the presence of water, the dielectric constant of the medium increases, C x The capacitance increases significantly, thus producing a corresponding change in capacitance.

[0017] The oscillation excitation unit 200 is used to generate a high-frequency AC signal, and load the corresponding high-frequency AC signal onto the medium through two sensing pads 100, and convert the capacitance change signal generated by the sensing capacitor according to the liquid level change in the target container into an AC voltage signal. The filter shaping unit 300 is used to convert the received AC voltage signal into a DC signal.

[0018] Amplification unit 400 is used to isolate and amplify DC signals and transmit the generated water level status signal to the corresponding main control unit. The water level status signal is used to characterize whether there is water in the target container.

[0019] In the aforementioned water level detection circuit, two sensing pads 100, an oscillation excitation unit 200, a filtering and shaping unit 300, and an amplification unit 400 are used. The two sensing pads 100 sense the change in the dielectric constant of the liquid in the target container, forming a changing sensing capacitance. The oscillation excitation unit 300 generates a high-frequency AC signal, which is then applied to the medium (the corresponding liquid or air) through the two sensing pads 100. The capacitance change signal generated by the sensing capacitance according to the liquid level change in the target container is converted into an AC voltage signal. The filtering and shaping unit 300 converts the received AC voltage signal into a DC signal. The amplification unit 400 isolates and amplifies the DC signal, and transmits the generated water level status signal to the corresponding main control unit. This allows for the construction of a water level detection circuit using simple components to detect whether there is a lack of water in a plastic container. This solves the problems of easy failure of water level detection and easy corrosion of electrodes in related technologies for coffee machines, achieving the beneficial effects of reducing design costs and improving the performance of coffee machines.

[0020] In some embodiments, the oscillation excitation unit 200 includes a multivibrator and a coupling capacitor C7. The output of the multivibrator is electrically connected to the sensing pads 100 that serve as detection points on the two sensing pads 100 (see reference). Figure 2 In the PT2), coupling capacitor C7 electrically connects the two sensing pads 100, where, A multivibrator is used to oscillate and generate pulse signals, which are then output to the sensing pad 100 (reference) which serves as the detection point. Figure 2 PT2 in the middle.

[0021] In some alternative embodiments, the multivibrator includes a first switch Q1 and a second switch Q2. The input terminal of the first switch Q1 is electrically connected to a first power supply (+5V) and a first resistor R9. The controlled terminal of the first switch Q1 is electrically connected to the other end of the first resistor R9 and the input terminal of the second switch Q2. The output terminal of the first switch Q1 is electrically connected to a detection point and a second resistor R11. The controlled terminal of the second switch Q2 is electrically connected to a coupling capacitor C7 and another sensing pad 100 that is not used as a detection point. The output terminal of the second switch Q2 is electrically connected to a third resistor R8 and a first capacitor C5. The other end of the third resistor R8 is grounded. The other end of the first capacitor C5 is electrically connected to the other ends of a fourth resistor R12, a fifth resistor R7, and a second resistor R11. The other end of the fourth resistor R12 is electrically connected to the detection point. The other end of the fifth resistor R7 is grounded. The first switch Q1 and the second switch Q2 are driven to be turned on alternately in sequence to oscillate and generate corresponding pulse signals.

[0022] In some embodiments, both the first switching transistor Q1 and the second switching transistor Q2 are BC846B type transistors.

[0023] In this embodiment, the first switch Q1 and the second switch Q2 alternately switch between on and off, thereby oscillating to generate a pulse signal. During one switching cycle, the input terminal of the first switch Q1 is connected to the first power supply, and the controlled terminal is connected to the first power supply through the first resistor R9, so the first switch Q1 is turned on. At this time, the controlled terminal of the second switch Q2 is pulled low, and the second switch Q2 is turned off. Simultaneously, as the voltage at the input terminal of the first switch Q1 is pulled low due to conduction, the output voltage of the first switch Q1 charges the first capacitor C5 through the voltage divider circuit composed of the fifth resistor R7 and the second resistor R11. When the voltage at the input terminal of the first switch Q1 is pulled low, the first capacitor C5 charges the controlled terminal of the second switch Q2 in reverse, and the second switch Q2 is turned on. The input terminal of the second switch Q2 is pulled low, causing the input terminal of the first switch Q1 to be pulled low, and the first switch Q1 is turned off. Afterwards, after the reverse charging of the first capacitor C5 is completed, the controlled terminal of the second switch Q2 is pulled low, and the second switch Q2 is turned off. The input terminal of the second switch Q2 is pulled high, simultaneously causing the controlled terminal of the first switch Q1 to be pulled high, and the first switch Q1 is turned on. In this way, the switching between on and off is repeated, and high and low level pulse signals are output along the output terminal of the first switch Q1.

[0024] Two sensing pads 100 form a first sensing capacitance when there is no water in the target container (plastic container) and a second sensing capacitance when there is water in the target container, based on corresponding pulse signals.

[0025] The coupling capacitor C7 is used to convert the capacitance change signal generated by the difference between the second sensing capacitor and the first sensing capacitor into an AC voltage signal corresponding to the detection point.

[0026] In some embodiments, another sensing pad 100 that is not used as a detection point is also electrically connected to a storage capacitor (composed of capacitors C2 and C3 connected in series). The storage capacitor is used to increase the capacitance value corresponding to the first sensing capacitor or the second sensing capacitor, so as to enhance the amplitude of the capacitance change signal.

[0027] In this embodiment, since the capacitance value of the first sensing capacitor or the second sensing capacitor is very small, it cannot be effectively read. In this embodiment, by examining the storage capacitor, that is, by increasing the overall capacitance value of the first sensing capacitor and the second sensing capacitor, the filtering and shaping unit 300 and the amplification unit 400 can read the effective capacitance value, thereby accurately cross the capacitance change signal and thus sense whether there is water in the target container.

[0028] In some embodiments, the filter shaping unit 300 includes a coupling capacitor C6, a switching diode D1, a second capacitor C1, and a sixth resistor R1. One end of the coupling capacitor C6 is electrically connected to a detection point, and the other end is electrically connected to the intermediate tap point of the switching diode D1. The anode of the switching diode D1 is grounded, and the cathode of the switching diode D1 is electrically connected to the second capacitor C1 and the sixth resistor R1, and is connected to the output terminal of the filter shaping unit 300. The other ends of the second capacitor C1 and the sixth resistor R1 are connected to each other, and the second capacitor C1 and the sixth resistor R1 form an RC filter unit. The coupling capacitor C6 is used to couple the AC voltage signal to the switching diode D1; Switching diode D1 is used to rectify AC voltage signals into DC signals; An RC filter unit is used to filter DC signals.

[0029] In some embodiments, the switching diode includes a BAV99 type dual series high-speed switching diode.

[0030] In some embodiments, the amplification unit 400 includes a voltage comparator U1, a coupling resistor R3, and a third switch Q3. The inverting input of the voltage comparator U1 is connected to the input of the amplification unit 400. The non-inverting input of the voltage comparator U1 is electrically connected to a first pull-down resistor R4, a feedback resistor R2, and a first pull-up resistor R5. The other end of the first pull-down resistor R4 is grounded. The other end of the feedback resistor R2 is electrically connected to the output of the voltage comparator U1. The other end of the first pull-up resistor R5 is electrically connected to a first power supply (+5V). The output of the voltage comparator U1 is also electrically connected to the controlled terminal of the third switch Q3 through a series coupling resistor R3. The input of the third switch Q3 is electrically connected to the first power supply through a series second pull-up resistor R6. The input of the third switch Q3 is also connected to the output of the amplification unit 400. The input of the third switch Q3 is also electrically connected to a series resistor R13 and a light-emitting diode LED1. The output of the third switch Q3 is grounded. The first pull-down resistor R4 and the first pull-up resistor R5 form a corresponding voltage divider circuit and provide a reference voltage to the non-inverting input of the voltage comparator U1.

[0031] Voltage comparator U1 is used to compare the level of the DC signal received at its inverting input terminal with the reference voltage received at its non-inverting input terminal, and output a comparison signal along the output terminal of voltage comparator U1.

[0032] In this embodiment, the voltage comparator U1 includes an LM358D operational amplifier.

[0033] The coupling resistor R3 is used to couple the comparison signal to the controlled terminal of the third switch Q3; The third switch Q3 is used to control the on / off state of the input and output terminals of the third switch Q3 according to the level of the comparison signal received at the controlled terminal of the third switch Q3, and to generate a water level status signal at the input terminal of the third switch Q3.

[0034] In this embodiment, the third switch Q3 includes a BC846B type transistor.

[0035] In this embodiment, the AC voltage signal is coupled and rectified into a DC signal through coupling capacitor C6 and switching diode D1, and then sent to the inverting input of voltage comparator U1. This DC signal is compared with the reference voltage provided by the voltage divider circuit. When there is water in the container, the DC signal level is higher than the reference voltage level, voltage comparator U1 outputs a high level, the input and output of the third switching transistor Q3 are connected, LED1 is off, and amplifier unit 400 outputs a high level indicating the presence of water. When there is no water in the container, the DC signal level is not higher than the reference voltage level, voltage comparator U1 outputs a low level, the input and output of the third switching transistor Q3 are disconnected, LED1 lights up, and amplifier unit 400 outputs a low level indicating the absence of water.

[0036] This application also provides a coffee machine, including a plastic container, and a sensing probe that is coupled and electrically connected to a water level detection circuit inside the plastic container. The water level detection circuit is the same as the water level detection circuit in the above embodiment, and the sensing probe is a sensing pad.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive elements that are not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0038] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A water level detection circuit for a coffee machine, characterized in that, The system includes two sensing pads (100), an oscillation excitation unit (200), a filtering and shaping unit (300), and an amplification unit (400). The two sensing pads (100) are mounted on the bottom of the target container and spaced apart. The oscillation excitation unit (200) is electrically connected to the two sensing pads (100). One of the two sensing pads (100) is electrically connected to the oscillation excitation unit (200) and also electrically connected to the input terminal of the filtering and shaping unit (300). The output terminal of the filtering and shaping unit (300) is electrically connected to the input terminal of the amplification unit (400). The output terminal of the amplification unit (400) is coupled and electrically connected to the main control unit of the coffee machine. The two sensing pads (100) are used to form a sensing capacitance with the medium of the target container; The oscillation excitation unit (200) is used to generate a high-frequency AC signal, and load the corresponding high-frequency AC signal onto the medium through the two sensing pads (100), and convert the capacitance change signal generated by the sensing capacitor according to the liquid level change in the target container into an AC voltage signal. The filtering and shaping unit (300) is used to convert the received AC voltage signal into a DC signal; The amplification unit (400) is used to isolate and amplify the DC signal and transmit the generated water level status signal to the corresponding main control unit, wherein the water level status signal is used to characterize whether there is water in the target container.

2. The water level detection circuit according to claim 1, characterized in that, The oscillation excitation unit (200) includes a multivibrator and a coupling capacitor. The output terminal of the multivibrator is electrically connected to the two sensing pads (100) that serve as detection points. The coupling capacitor is electrically connected to the two sensing pads (100). The multivibrator is used to generate a pulse signal and output it to the sensing pad (100) which serves as the detection point. The two sensing pads (100) form a first sensing capacitance when there is no water in the target container and a second sensing capacitance when there is water in the target container, based on the corresponding pulse signal. The coupling capacitor is used to convert the capacitance change signal generated by the difference between the second sensing capacitor and the first sensing capacitor into an AC voltage signal corresponding to the detection point.

3. The water level detection circuit according to claim 2, characterized in that, Another sensing pad (100) that is not used as a detection point is also electrically connected to a storage capacitor, which is used to increase the capacitance value corresponding to the first sensing capacitor or the second sensing capacitor to enhance the amplitude of the capacitance change signal.

4. The water level detection circuit according to claim 2, characterized in that, The multivibrator includes a first switch and a second switch. The input terminal of the first switch is electrically connected to a first power supply and a first resistor. The controlled terminal of the first switch is electrically connected to the other end of the first resistor and the input terminal of the second switch. The output terminal of the first switch is electrically connected to a detection point and a second resistor. The controlled terminal of the second switch is electrically connected to the coupling capacitor and another sensing pad (100) that is not used as a detection point. The output terminal of the second switch is electrically connected to a third resistor and a first capacitor. The other end of the third resistor is grounded. The other end of the first capacitor is electrically connected to a fourth resistor, a fifth resistor, and the other end of the second resistor. The other end of the fourth resistor is electrically connected to the detection point. The other end of the fifth resistor is grounded. The first switch and the second switch are driven to alternately conduct in sequence to oscillate and generate corresponding pulse signals.

5. The water level detection circuit according to claim 4, characterized in that, Both the first and second switching transistors are BC846B type transistors.

6. The water level detection circuit according to claim 1, characterized in that, The filter shaping unit (300) includes a coupling capacitor, a switching diode, a second capacitor, and a sixth resistor. One end of the coupling capacitor is electrically connected to a detection point, and the other end is electrically connected to the intermediate tap of the switching diode. The anode of the switching diode is grounded, and the cathode of the switching diode is electrically connected to the second capacitor and the sixth resistor, and is connected to the output terminal of the filter shaping unit (300). The other ends of the second capacitor and the sixth resistor are connected together, and the second capacitor and the sixth resistor form an RC filter unit. The coupling capacitor is used to couple the AC voltage signal to the switching diode; The switching diode is used to rectify the AC voltage signal into a DC signal; The RC filter unit is used to filter DC signals.

7. The water level detection circuit according to claim 6, characterized in that, The switching diode includes a BAV99 type dual series high-speed switching diode.

8. The water level detection circuit according to claim 1, characterized in that, The amplification unit (400) includes a voltage comparator, a coupling resistor, and a third switching transistor. The inverting input of the voltage comparator is connected to the input of the amplification unit (400). The non-inverting input of the voltage comparator is electrically connected to a first pull-down resistor, a feedback resistor, and a first pull-up resistor. The other end of the first pull-down resistor is grounded. The other end of the feedback resistor is electrically connected to the output of the voltage comparator. The other end of the first pull-up resistor is electrically connected to a first power supply. The output of the voltage comparator is also electrically connected to the controlled terminal of the third switching transistor via the coupling resistor in series. The input of the third switching transistor is electrically connected to the first power supply via a second pull-up resistor in series. The input of the third switching transistor is also connected to the output of the amplification unit (400). The output of the third switching transistor is grounded. The first pull-down resistor and the first pull-up resistor form a corresponding voltage divider circuit and provide a reference voltage to the non-inverting input terminal of the voltage comparator. The voltage comparator is used to compare the level of the DC signal received at its inverting input terminal with the reference voltage received at its non-inverting input terminal, so as to output a comparison signal along the output terminal of the voltage comparator. The coupling resistor is used to couple the comparison signal to the controlled terminal of the third switch. The third switch is used to control the switching between the input and output terminals of the third switch based on the level of the comparison signal received by the controlled terminal of the third switch, and to generate the water level status signal at the input terminal of the third switch.

9. The water level detection circuit according to claim 8, characterized in that, The voltage comparator includes an LM358D operational amplifier, and the third switching transistor includes a BC846B transistor.

10. A coffee machine, comprising a plastic container, wherein a sensing probe is disposed within the plastic container and electrically coupled to a water level detection circuit, characterized in that, The water level detection circuit includes the water level detection circuit according to any one of claims 1 to 9, and the sensing probe is the sensing pad.

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