Sensor circuit, MCU liquid level sensor, and ink cartridge

Abstract

The present application discloses a sensor circuit, an MCU liquid level sensor and an ink cartridge. The sensor circuit includes a power supply circuit, a control circuit and a sensing circuit. The power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit and a cascade circuit. The comparator and the heating branch are respectively connected to the cascade circuit, and the diode circuit is electrically connected to the selection circuit. The control circuit is electrically connected to the selection circuit and is used to control the operation of the selection circuit to directly connect the diode circuit to the cascade circuit or connect it to the heating branch. The sensing circuit is electrically connected to the cascade circuit and is used to output a liquid level signal of the liquid. In the present application, the control circuit controls the diode circuit to connect to the heating branch to achieve the heating function, and the control circuit controls the diode circuit to directly connect to the cascade circuit to achieve the liquid level detection function. Its control method is flexible, and a set of control circuits can control the heating and liquid level detection functions at the same time, simplifying the circuit structure and saving costs.

Description

Technical Field

[0001] The present application relates to the technical field of liquid heating and liquid level detection, and particularly relates to a sensor circuit, an MCU liquid level sensor, and an ink cartridge including the sensor circuit. Background Art

[0002] Common sensors for measuring the liquid level position, such as ultrasonic sensors, float-type liquid level sensors, floating ball-type liquid level sensors, static pressure-type liquid level sensors, etc., all have the problems of large volume and high cost.

[0003] To solve the above problems of volume and cost, two ways of heating and detecting the liquid level in the prior art are designed. One is to design a dedicated heating circuit and a detection circuit, so as to heat the liquid through the heating circuit and detect the liquid level through the detection circuit. However, in this way, since both a heating element and a detection element are provided, the volume is still large and the control is not flexible enough.

[0004] The other is to set the heater and the sensor in the same circuit. As shown in Figure 1 and Figure 2 , a row of heaters 10 and sensors 20 are arranged along the height direction of the liquid level. Among them, the heaters 10 and the sensors 20 are arranged at intervals, so as to heat the liquid through the heaters 10 and detect the liquid level height of the liquid through the sensors 20. However, this way also has both a heating element and a detection element, and two sets of control circuits need to be designed to control heating and detection respectively to meet the functions of heating and detection. Its cost is also high, the control is cumbersome, the volume is large, and the space is wasted. Summary of the Invention

[0005] In order to overcome the problems existing in the above prior art, the main purpose of the present application is to provide a sensor circuit that can simultaneously realize heating and detection functions, has flexible control, small volume, and low cost with a set of control circuit.

[0006] To achieve the above purpose, the present application specifically adopts the following technical solutions:

[0007] The present application provides a sensor circuit for heating a liquid or detecting the liquid level of a liquid; the sensor circuit includes:

[0008] A power supply circuit, the power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit, and a cascade circuit. The comparator and the heating branch are respectively connected to the cascade circuit, and the diode circuit is electrically connected to the selection circuit;

[0009] A control circuit, electrically connected to the selection circuit, for controlling the operation of the selection circuit so that the diode circuit is directly electrically connected to the cascade circuit or electrically connected to the heating branch;

[0010] A sensing circuit, electrically connected to the cascade circuit, for outputting a liquid level signal of the liquid.

[0011] In a specific embodiment, the cascade circuit includes a first-level circuit, a second-level circuit, and a third-level circuit connected in parallel. The comparator is electrically connected to the first-level circuit, the second-level circuit, and the third-level circuit respectively. The states of the first-level circuit, the second-level circuit, and the third-level circuit are controlled by the magnitude of the voltage input to the comparator. The sensing circuit is electrically connected to the third-level circuit, and the diode circuit is directly electrically connected to the second-level circuit or electrically connected to the heating branch.

[0012] In a specific embodiment, the heating branch is electrically connected to the second-level circuit. The selection circuit includes a first selection circuit. The diode circuit is electrically connected to the first selection circuit, and the control circuit is electrically connected to the first selection circuit for controlling the first selection circuit to be directly electrically connected to the second-level circuit or electrically connected to the heating branch.

[0013] In a specific embodiment, the second-level circuit includes a MOS transistor Q2, a resistor R2, and a resistor R3. The resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2. The heating branch is connected in parallel to the resistor R2, and the control circuit is used to control the first selection circuit to be electrically connected to the heating circuit or the resistor R2.

[0014] In a specific embodiment, the second-level circuit includes a current mirror circuit, a resistor R2, and a resistor R3. The resistor R2 and the resistor R3 are connected in parallel and then electrically connected to the current mirror circuit. The heating branch is connected in parallel to the resistor R2, and the control circuit is used to control the first selection circuit to be electrically connected to the heating branch or the resistor R2.

[0015] In a specific embodiment, the selection circuit includes a fourth selection circuit. The current mirror circuit includes at least two MOS transistor branches connected in parallel. Each MOS transistor branch is respectively connected to an input power supply through the fourth selection circuit, and the fourth selection circuit is electrically connected to the control circuit. The operation of the fourth selection circuit is controlled by the control circuit to switch each MOS transistor branch to be connected to the input power supply.

[0016] In a specific embodiment, the heating branch is electrically connected to the three - stage circuit. The selection circuit includes a second selection circuit. The diode circuit is electrically connected to the second selection circuit. The control circuit is electrically connected to the second selection circuit and is used to control the second selection circuit to be connected to the secondary circuit or electrically connected to the heating branch.

[0017] In a specific embodiment, the three - stage circuit includes MOS transistor Q3 and resistor R4. The MOS transistor Q3 and the resistor R4 are connected in series, and the heating branch is in parallel with the resistor R4.

[0018] In a specific embodiment, the three - stage circuit includes a current mirror circuit and resistor R4. The resistor R4 is connected in series with the current mirror circuit, and the heating branch is in parallel with the resistor R4.

[0019] In a specific embodiment, the selection circuit includes a fifth selection circuit. The current mirror circuit includes at least two MOS transistor branches connected in parallel. Each of the MOS transistor branches is respectively connected to the input power supply through the fifth selection circuit, and the fifth selection circuit is electrically connected to the control circuit. The operation of the fifth selection circuit is controlled through the control circuit to switch each of the MOS transistor branches to be connected to the input power supply.

[0020] In a specific embodiment, the heating branch is electrically connected to the first - stage circuit. The selection circuit includes a third selection circuit. The diode circuit is electrically connected to the third selection circuit. The control circuit is electrically connected to the third selection circuit and is used to control the third selection circuit to be electrically connected to the secondary circuit or electrically connected to the heating branch.

[0021] In a specific embodiment, the first - stage circuit includes MOS transistor Q1, resistor R1, and diode D0. The resistor R1 and the diode D0 are connected in parallel and then connected in series with the MOS transistor Q1, and the heating branch is in parallel with the diode D0.

[0022] In a specific embodiment, the three - stage circuit includes a current mirror circuit, resistor R1, and diode D0. The resistor R1 and the diode D0 are connected in parallel and then connected in series with the current mirror circuit, and the heating branch is in parallel with the diode D0.

[0023] In a specific embodiment, the selection circuit includes a sixth selection circuit. The current mirror circuit includes at least two MOS transistor branches connected in parallel. Each of the MOS transistor branches is respectively connected to the input power supply through the sixth selection circuit, and the sixth selection circuit is electrically connected to the control circuit. The operation of the sixth selection circuit is controlled through the control circuit to switch each of the MOS transistor branches to be connected to the input power supply.

[0024] In a specific embodiment, the sensing circuit is electrically connected to the control circuit, and the control circuit is configured to control the diode circuit to be electrically connected to the heating branch or directly connected to the secondary circuit according to the output result of the sensing circuit.

[0025] In a specific embodiment, the tertiary circuit includes a current output interface and a voltage output interface. The sensing circuit includes a first sensing diode branch, a second sensing diode branch, and an amplifying circuit. The first sensing diode branch and the second sensing diode branch are in parallel, and the first sensing diode branch is connected to the current output interface, and the amplifying circuit is connected to the first sensing diode branch and the second sensing diode branch.

[0026] Correspondingly, the present application further provides an MCU liquid level sensor for liquid level detection in a cavity. The MCU liquid level sensor includes an MCU chip and a plurality of detection circuits. The detection circuit includes a power supply circuit and a sensing circuit. The plurality of detection circuits are respectively arranged at different heights in the cavity. The MCU chip is electrically connected to each of the detection circuits for controlling the heating or liquid level measurement of each of the detection circuits, and determining the medium environment where the detection circuit is located according to the signal output by the detection circuit to determine the liquid level.

[0027] In a specific embodiment, the power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit, and a cascading circuit. The comparator and the heating branch are respectively connected to the cascading circuit. The diode circuit is electrically connected to the selection circuit. The MCU chip controls the operation of the selection circuit to switch the diode circuit to be electrically connected to the heating branch or directly electrically connected to the cascading circuit. The sensing circuit is electrically connected to the cascading circuit for outputting a liquid level signal of the liquid.

[0028] In a specific embodiment, the power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit, and a cascading circuit. The comparator and the heating branch are respectively connected to the cascading circuit. The diode circuit is electrically connected to the selection circuit. The MCU chip controls the operation of the selection circuit to switch the diode circuit to be electrically connected to the heating branch or directly electrically connected to the cascading circuit. The sensing circuit is electrically connected to the cascading circuit for outputting a liquid level signal of the liquid.

[0029] In a specific embodiment, the cascade circuit includes a first-stage circuit, a second-stage circuit, and a third-stage circuit connected in parallel. The comparator is electrically connected to the first-stage circuit, the second-stage circuit, and the third-stage circuit respectively. The sensing circuit is electrically connected to the third-stage circuit. The heating branch is electrically connected to the first-stage circuit, the second-stage circuit, or the third-stage circuit. The MCU chip is configured to control the diode circuit to be electrically connected to the heating branch or directly connected to the second-stage circuit.

[0030] In a specific embodiment, the MCU liquid level sensor further includes a calculation circuit, which is electrically connected to the detection circuit and the MCU chip respectively, and is configured to convert the signal output by the detection circuit into a digital signal and input it into the MCU chip.

[0031] Correspondingly, the present application further provides an ink cartridge, which includes a cartridge body and the sensor circuit as described in any of the above embodiments. The sensor circuit is detachably disposed on the cartridge body.

[0032] Compared with the prior art, the sensor circuit of the present application includes a power supply circuit, a control circuit, and a sensing circuit. When it is necessary to heat the liquid, the control circuit controls the selection circuit to connect the diode circuit to the heating branch, so as to heat the liquid by the heat generated by the diode circuit, realizing the heating function. When it is necessary to detect the liquid level of the liquid, the control circuit controls the selection circuit to directly connect the cascade circuit to the diode circuit, so as to detect the liquid level of the liquid through the output signals of the power supply circuit, the control circuit, and the sensing circuit, realizing the liquid level detection function. This control method is flexible. One set of control circuits can control the heating and liquid level detection functions simultaneously, simplifying the circuit structure and saving costs. Description of the Drawings

[0033] Figure 1 It is a partial structural schematic diagram of a liquid level detection device in the prior art.

[0034] Figure 2 is Figure 1 a partial circuit diagram of the liquid level detection device in

[0035] Figure 3 It is a circuit diagram of the sensor circuit provided in Embodiment 1 of the present application.

[0036] Figure 3A It is a circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 1 of the present application.

[0037] Figure 3B It is a circuit diagram of the sensing circuit in the sensor circuit provided in Embodiment 1 of the present application.

[0038] Figure 4 It is a schematic diagram of the voltage and temperature correspondence relationship provided in Embodiment 1 of the present application.

[0039] Table 1 is a table showing the corresponding relationship between the ratio u and temperature.

[0040] Table 2 is a table showing the corresponding relationship between the ratio u and temperature in an air medium.

[0041] Table 3 is a table showing the corresponding relationship between the ratio u and temperature in an ink medium.

[0042] Figure 5 This is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 2 of the present application.

[0043] Figure 6 This is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 3 of the present application.

[0044] Figure 7 This is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 5 of the present application.

[0045] Figure 8 This is the schematic block diagram of the chip and the detection circuit provided in Embodiment 7 of the present application.

[0046] Figure 9 This is the schematic block diagram of the ink cartridge provided in Embodiment 8 of the present application. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] In the description of the present application, unless otherwise clearly specified and defined, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated, the term "plurality" means two or more; the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0049] In the description of this specification, it should be understood that the orientation terms such as "upper" and "lower" described in the embodiments of this application are described from the angles shown in the drawings and should not be construed as limitations on the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0050] Embodiment 1

[0051] Referring to the Figure 3 and Figure 3A as shown, Figure 3 This is a sensor circuit provided by an embodiment of this application. Figure 3A It is Figure 3 a circuit diagram of the power supply circuit 301 in the sensor circuit in . The sensor circuit is used to heat a liquid or detect the liquid level. The sensor circuit includes: a power supply circuit 301, a control circuit 305, and a sensing circuit 302. The power supply circuit 301 includes a comparator U1, a heating branch L, a diode circuit 304, a first selection circuit 303, and a cascaded circuit. Among them, the comparator U1 and the heating branch L are respectively connected to the cascaded circuit, and the diode circuit 304 is electrically connected to the first selection circuit 303. The control circuit 305 is electrically connected to the first selection circuit 303 and is used to control the operation of the first selection circuit 303 so that the diode circuit 304 is directly electrically connected to the cascaded circuit or electrically connected to the heating branch L.

[0052] Specifically, the cascaded circuit includes a first-stage circuit 306, a second-stage circuit 307, and a third-stage circuit 308. The first-stage circuit 306 includes a MOS transistor Q1, a resistor R1, and a diode D0. Among them, the resistor R1 and the diode D0 are connected in parallel and then connected in series with the MOS transistor Q1. The second-stage circuit 307 includes a MOS transistor Q2, a resistor R2, and a resistor R3. The resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2. The heating branch L is connected in parallel to the resistor R2. The third-stage circuit 308 includes a MOS transistor Q3, a resistor R4, a current output interface, and a voltage output interface. The MOS transistor Q3 and the resistor R4 are connected in series. The current output interface and the voltage output interface are connected to the source electrode of the MOS transistor Q3. Among them, the current output interface is used to output a current Iref, and the voltage output interface is used to output a voltage Vref. The output current Iref is used to drive the sensing circuit 302, and the output voltage Vref is used to measure the liquid level parameter. The diode circuit 304 includes a plurality of diodes D1, D2... DN connected in parallel. For example, it can be 10 diodes connected in parallel. The diode circuit 304 is electrically connected to the first selection circuit 305.

[0053] Further, the resistance values of the resistors in the primary circuit 306, the secondary circuit 307, and the tertiary circuit 308 are the same, and the sizes of the MOS transistors Q1, Q2, and Q3 are the same.

[0054] The drains of the MOS transistors Q1, Q2, and Q3 are connected to the input power supply VCC. The comparator U1 includes an input terminal Va and an input terminal Vb. The output terminal of the comparator U1 is electrically connected to the gates of the MOS transistors Q1, Q2, and Q3 respectively. By controlling the magnitudes of the voltages flowing into the input terminal Va and the input terminal Vb of the comparator U1, the operating states of the MOS transistors are controlled.

[0055] The heating branch L is connected in parallel with the resistor R2 in the secondary circuit. The first selection circuit 303 is controlled by the control circuit 305 to selectively connect the heating branch L or the resistor R2 of the secondary circuit.

[0056] The control circuit 305 is connected to the first selection circuit 303 to control the first selection circuit 303 to connect the heating branch L or the secondary circuit 307. Specifically, the control circuit 305 can load a preset program to control the first selection circuit 303 to connect the heating branch L or the secondary circuit 307 at a certain time interval, such as two minutes.

[0057] When the first selection circuit 303 is electrically connected to the heating branch L, a specific current can be input to the diode circuit 304, causing the diode circuit 304 to generate heat and realizing the heating function; when the first selection circuit 303 is electrically connected to the resistor R2 in the secondary circuit 307, that is, the diode circuit 304 is electrically connected to the secondary circuit 307, the power supply circuit outputs a stable voltage Vref for measuring the liquid level parameter.

[0058] Generally, when the diode voltage is less than 0.8V, the internal resistance of the diode changes. Depending on the diode, the heating power also changes dynamically. When the voltage is greater than 0.8V, at a certain large current, the voltage of the diode is basically unchanged. The corresponding heating power P = I * V (I is the current and V is the voltage). At this time, the heating power of the diode is determined by the heating current. Therefore, the greater the current in the diode circuit, the greater the corresponding heating power, and the heating time can be reduced accordingly.

[0059] To facilitate controlling the heating duration of the diode circuit according to the magnitude of the current in the heating branch, the sensor circuit further includes a feedback circuit. The feedback circuit is electrically connected to the heating branch and the control circuit respectively. The feedback circuit is used to feedback the magnitude of the current in the heating branch, enabling the control circuit to control the duration of the diode circuit connecting to the heating branch according to the magnitude of the current in the heating branch feedback by the feedback circuit, that is, to control the heating duration of the diode circuit.

[0060] The heating time of the diode circuit is related to the magnitude of the heating current I2c (the current in the heating branch). When the heating current I2c is larger, the heating time of the diode circuit can be relatively reduced. For example, when the heating current I2c is 1 A, the heating time of the diode circuit is 5 minutes; when the heating current I2c is 500 mA, the heating time of the diode circuit is 10 minutes.

[0061] In another embodiment, in order to increase the heating power, multiple dummies (resistors unrelated to circuit matching) can also be provided in the diode circuit. For example, several or dozens of dummies can be provided, and the dummies are also controlled by switches to meet the heating power of the diode circuit.

[0062] Refer to Figure 3B As shown, it is the circuit diagram of the sensing circuit in the sensor circuit provided by the embodiment of the present application. The sensing circuit 302 includes a first sensing diode branch 401, a second sensing diode branch 402, and an amplifying circuit 403. The first sensing diode branch 401 includes a first diode A, and the second sensing diode circuit 402 includes a second diode B. The first sensing diode branch 401 and the second sensing diode branch 402 are connected in parallel, and the current output interfaces of the power supply circuit 301 are respectively connected to the first sensing diode branch 401 and the second sensing diode branch 402. The amplifying circuit 403 is connected to the first sensing diode branch 401 and the second sensing diode branch 402, and is used to amplify the voltage difference between the first sensing diode branch 401 and the second sensing diode branch 402. The output end of the amplifying circuit 403 is used to output the amplified voltage difference. The voltage difference output by the amplifying circuit 403 and the voltage output by the voltage output interface of the power supply circuit 301 can be used for subsequent calculation of the corresponding liquid level information.

[0063] In addition, the control circuit 305 can also be connected to the output end of the sensing circuit 302, and control the first selection circuit 303 to connect to the heating branch L or the secondary circuit 307 according to the output result of sampling the sensing circuit 302.

[0064] As Figure 4As shown, it is a schematic diagram of the voltage varying with temperature. The voltage includes the output voltage Vref of the power supply circuit, the diode voltage in the second sensing diode branch, the output voltage of the amplifier in the sensing circuit, and the voltage difference between the first sensing diode branch and the second sensing diode branch, which is a schematic diagram of the change with temperature. When controlling Va = Vb, MOS transistors Q1, Q2, and Q3 are connected to the same node. Due to the principle of the current mirror circuit, the currents I1 flowing into the first-stage circuit, I2 flowing into the second-stage circuit, and I3 flowing into the third-stage circuit are equal; the current I1a flowing into the diode in the first-stage circuit is equal to the current magnitude I2a flowing into the resistor R2 in the second-stage circuit; the current I1b flowing into the resistor in the first-stage circuit is equal to the current magnitude I2b flowing into the resistor R3 in the second-stage circuit; the output voltage of the power supply circuit is determined by the resistance ratios in the first-stage circuit, the second-stage circuit, and the third-stage circuit; the magnitude of the output current Iref is equal to the magnitude of the current I1 flowing into the first-stage circuit; the currents I1 flowing into the first-stage circuit, I2 flowing into the second-stage circuit, and I3 flowing into the third-stage circuit are equal; the magnitude of the current i1 flowing into the first sensing diode branch is equal to the magnitude of the above output current Iref, the current flowing into the second sensing diode branch is five times the current flowing into the first sensing diode branch, and the ratio of the voltage drop VB on the second diode B to the pressure difference △VB between the first sensing diode branch and the second sensing diode branch is related to the magnitude of the current flowing into the sensing circuit, that is, the sensing circuit can be designed according to the current flowing into the sensing circuit. The ambient temperature affects the pressure difference △VB, such as Figure 4 As shown, the higher the temperature, the larger the pressure difference △VB, and the larger the output voltage of the amplifier in the sensing circuit; u is determined according to the ratio of the pressure difference △VB between the first sensing diode branch and the second sensing diode branch, the amplification factor of the amplifier, and the output voltage Vref of the power supply circuit. Under different heating temperatures and medium environments, the ratio u is different. That is, when the heating temperature is constant, the medium environment can be determined according to the ratio u, or when the medium environment is constant, the heating temperature can be determined according to the ratio u. Among them, the output voltage Vref is determined by the resistance ratios of resistor R2, resistor R3, and resistor R4, and the resistance values of resistor R2, resistor R3, and resistor R4 have little influence on the output voltage Vref.

[0065] For example: The relational expression of the ratio u in the ink environment is:

[0066] u = (M1 * α * △VB / Vref) + N1

[0067] Specific fitting relation example: u = (0.56 * α * △VB / Vref) + 24.

[0068] Among them, α is the amplification factor of the amplifier circuit, △VB is the voltage difference of the sensing circuit, Vref is the output voltage of the power supply circuit, M1 is the slope, N1 is the intercept, which are obtained by fitting multiple experiments. The u relationship should be a linear relationship. Specifically, M1 and N1 can be determined by fitting multiple sets of experimental data.

[0069] In a gas medium environment, the relational expression of the ratio u is:

[0070] u = (M2 * α * △VB / Vref) + N2

[0071] A specific example of the fitting relationship: u = (0.48 * α * △VB / Vref) + 28.

[0072] Among them, α is the amplification factor of the amplifier circuit, △VB is the voltage difference of the sensing circuit, Vref is the output voltage of the power supply circuit, M2 is the slope, N2 is the intercept, which are obtained by fitting multiple experiments. The u relationship should be a linear relationship. Specifically, M2 and N2 can be determined by fitting multiple sets of experimental data.

[0073] For the ratio u in different media, the corresponding relationship between the pressure difference △VB and the output voltage Vref of the power supply circuit is different; there is a corresponding relationship between the ratio u and the heating temperature. The higher the heating temperature, the larger the ratio u in the same medium environment; in different medium environments, the same ratio u corresponds to different medium environment temperatures.

[0074] In different media, the corresponding relationship of the ratio u between the pressure difference △VB and the output voltage Vref of the power supply circuit is different. As shown in Table 1, according to the relationship of the ratio u in the air medium, a corresponding table of the ratio u can be established. The amplification factor of the amplifier circuit for the voltage difference △VB is set to 16, the output voltage Vref is set to 1.28V. When the measured voltage difference △VB is 2mV, the corresponding ratio u in the air medium is 40.12, and the corresponding ratio u in the ink medium is 38.3; when the measured voltage difference △VB is 3mV, the corresponding ratio u in the air medium is 46.3, and the corresponding ratio u in the ink medium is 45.2; when the measured voltage difference △VB is 4mV, the corresponding ratio u in the air medium is 51.8, and the corresponding ratio u in the ink medium is 49.5.

[0075] Change the output voltage of the output voltage Vref to 1.22V, and keep the amplification factor of the amplifier circuit for the voltage difference △VB unchanged at 16. When the measured voltage difference △VB is 6mV, the corresponding ratio u in the air medium is 65.55, and the corresponding ratio u in the ink medium is 68.09; when the measured voltage difference △VB is 8mV, the corresponding ratio u in the air medium is 78.3, and the corresponding ratio u in the ink medium is 87.78; when the measured voltage difference △VB is 10mV, the corresponding ratio u in the air medium is 90.93, and the corresponding ratio u in the air medium is 97.34.

[0076] Change the output voltage of Vref to 1.20V. The amplification factor of the amplifier circuit for the voltage difference △VB remains unchanged and is set to 16. When measuring the voltage difference △VB of 8mV, the ratio u is 79.22 in air medium and 83.68 in ink medium; when measuring the voltage difference △VB of 9mV, the ratio u is 85.61 in air medium and 91.15 in ink medium.

[0077] There is a corresponding relationship between the ratio u and the heating temperature. The higher the heating temperature, the larger the ratio u in the same medium environment; in different medium environments, the same ratio u corresponds to different medium environment temperatures, as shown in Table 2 and Table 3. When the ratio u in air medium is 40.12, 46.3, 51.8, 65.55, 78.30, 90.93, 79.22, it corresponds to the heating temperatures of the diode circuit of 32.4°C, 36.2°C, 37°C, 45.4°C, 51.6°C, 68.2°C, 75.6°C, 79°C; when the ratio u in ink medium is 38.3, 45.2, 49.5, 68.09, 87.78, 97.34, 83.68, 91.15, it corresponds to the heating temperatures of the diode circuit of 33.2°C, 38.5°C, 41°C, 47°C, 56.5°C, 72°C, 78.7°C, 82.3°C.

[0078] In summary, the temperature can be determined according to the heat generation of the diode, the corresponding ratio u1 can be determined according to the temperature, the ratio u2 is calculated from the ratio of the pressure difference △VB and the output voltage Vref, the medium environment can be determined according to the ratio u1 and the ratio u2, and the liquid level information can be measured according to multiple sensor circuits. For example, the height of the device to be measured is h, and 2 sensor circuits are designed at equal intervals. When it is detected that both sensor circuits are in the liquid medium, it can be determined that the liquid level is above 2 / 3h of the device to be measured; when it is detected that the lower sensor circuit is in the liquid medium and the upper sensor circuit is in the air medium, it can be determined that the liquid level is between 1 / 3h and 2 / 3h of the device to be measured; when it is detected that both sensor circuits are in the air medium, it can be determined that the liquid level is below 1 / 3h of the device to be measured.

[0079] Embodiment 2

[0080] Based on Embodiment 1, the present application also discloses another specific implementation manner. Refer to Figure 5 as shown. Figure 5This is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 2 of the present application. The difference between this embodiment and the above embodiment is that in this embodiment, the secondary circuit includes a fourth selection circuit, a current mirror circuit, and a resistor. The fourth selection circuit is connected to the current mirror circuit, and the current mirror circuit is connected in series with the resistor. Specifically, the current mirror circuit includes a MOS transistor Q2 branch and a MOS transistor Q2' branch connected in parallel. Each of the MOS transistor branches is connected to the input power supply VCC through the fourth selection circuit, and the fourth selection circuit is electrically connected to the control circuit. The operation of the fourth selection circuit is controlled by the control circuit to switch each MOS transistor branch to be connected to the input power supply VCC.

[0081] In this embodiment, since the W / L (width-to-length ratio) of the MOS transistor Q2 and the MOS transistor Q2' are different, after each MOS transistor branch is connected to the input power supply VCC, the currents flowing through each MOS transistor branch are different, thereby controlling the magnitude of the output current of the heating branch, so that each MOS transistor branch outputs different current values after being connected to the input power supply.

[0082] The remaining structure is the same as that of the circuit in Embodiment 1 above and will not be described in detail.

[0083] Embodiment 3

[0084] Based on the above Embodiment 1, the present application also discloses another specific implementation manner. Refer to Figure 6 as shown Figure 6 This is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 3 of the present application. The difference between this embodiment and the above Embodiment 1 is that in this embodiment, the secondary circuit includes a MOS transistor Q2, a resistor R2, and a resistor R3. The resistor R2 and the resistor R3 are connected in parallel and then connected in series with the MOS transistor Q2; the tertiary circuit includes a MOS transistor Q3, a resistor R4, a current output interface, and a voltage output interface. Among them, the MOS transistor Q3 and the resistor R4 are connected in series, the resistor R4 is connected in parallel with the heating branch L, the source output of the MOS transistor Q3 is connected to the current output interface and the voltage output interface. The current output interface is used to output the current Iref, and the voltage output interface is used to output the voltage Vref. The diode circuit is electrically connected to the second selection circuit, and the control circuit is connected to the second selection circuit to control the second selection circuit to connect the heating branch L or connect the secondary circuit.

[0085] Further, the control circuit can load a preset program to control the second selection circuit to connect the heating branch or connect the secondary circuit at a certain time interval, such as 2 minutes; in addition, the control circuit can also be connected to the sensing circuit to control the second selection circuit to connect the heating branch or connect the secondary circuit according to the sensing result of the sensing circuit.

[0086] Embodiment 4

[0087] Based on Embodiment 3, the present application also discloses another specific implementation. The difference between this embodiment and Embodiment 3 is that in this embodiment, the three-stage circuit may further include a fifth selection circuit, a current mirror circuit, and a resistor. The fifth selection circuit is connected to the current mirror circuit, the current mirror circuit is connected to the current output interface and the voltage output interface, and the current output interface and the voltage output interface are connected to the resistor. Specifically, the current mirror circuit includes at least two MOS transistor branches connected in parallel. Each MOS transistor branch is respectively connected to the input power supply through the fifth selection circuit, and the fifth selection circuit is electrically connected to the control circuit. The operation of the fifth selection circuit is controlled by the control circuit to switch each MOS transistor branch to access the input power supply, so that each MOS transistor branch outputs different current values after connecting to the input power supply.

[0088] In this embodiment, the W / L (width-to-length ratio) of the MOS transistors in each MOS transistor branch is different, so that after each MOS transistor branch is connected to the input power supply, the current flowing through each MOS transistor branch is different, thereby controlling the magnitude of the output current of the heating branch, so that each MOS transistor branch outputs different current values after connecting to the input power supply.

[0089] Others are the same as the sensor circuit in the above Embodiment 3 and will not be elaborated.

[0090] Embodiment 5

[0091] Based on the above Embodiment 1, the present application also discloses yet another specific implementation. Refer to Figure 7 as shown Figure 7 is the circuit diagram of the power supply circuit in the sensor circuit provided in Embodiment 5 of the present application. The difference between this embodiment and the above Embodiment 1 is that in this embodiment, the first-stage circuit includes MOS transistor Q1, resistor R1, and diode D0. Among them, resistor R1 and diode D0 are connected in parallel and then connected in series with MOS transistor Q1, and the heating branch L is connected in parallel with diode D0; the second-stage circuit includes MOS transistor Q2, resistor R2, and resistor R3. Resistor R2 and resistor R3 are connected in parallel and then connected in series with MOS transistor Q2. The diode circuit is connected to the third selection circuit, and the control circuit is connected to the third selection circuit to control the third selection circuit to connect to the heating branch or the second-stage circuit.

[0092] Further, the control circuit can load a preset program to control the third selection circuit to connect to the heating branch or the second-stage circuit at a certain time interval, such as 2 minutes; in addition, the control circuit can also be connected to the sensing circuit to control the third selection circuit to connect to the heating branch or the second-stage circuit according to the sensing result of the sensing circuit.

[0093] Embodiment 6

[0094] Based on Embodiment 5, the present application also discloses another specific implementation. The difference between this embodiment and Embodiment 5 is that in this embodiment, the primary circuit may further include a sixth selection circuit, a current mirror circuit, a resistor, and a diode; the resistor and the diode are connected in parallel and then connected in series with the current mirror circuit, the current mirror circuit is connected to the sixth selection circuit, and the comparator is connected to the current mirror circuit. Specifically, the current mirror circuit includes at least two MOS transistor branches connected in parallel, each MOS transistor branch is respectively connected to the input power supply via the sixth selection circuit, and the sixth selection circuit is electrically connected to the control circuit, and the operation of the sixth selection circuit is controlled by the control circuit to switch each MOS transistor branch to be connected to the input power supply.

[0095] In this embodiment, the W / L (width-to-length ratio) of the MOS transistors in each MOS transistor branch is different, so that after each MOS transistor branch is connected to the input power supply, the current flowing through each MOS transistor branch is different, thereby controlling the magnitude of the output current of the heating branch, and enabling each of the MOS transistor branches to output different current values after being connected to the input power supply.

[0096] Others are the same as the sensor circuit in the above Embodiment 5 and will not be elaborated.

[0097] The sensor circuit of the present application includes a power supply circuit, a control circuit, and a sensing circuit. When it is necessary to heat the liquid, the control circuit controls the selection circuit to turn on the diode circuit to connect to the heating branch, so as to heat the liquid by the heat generated by the diode and achieve the heating function;

[0098] When it is necessary to detect the liquid level of the liquid, the control circuit controls the selection circuit to turn on the diode circuit to connect to the secondary circuit, so as to detect the liquid level of the liquid through the output signals of the power supply circuit, the control circuit, and the sensing circuit and achieve the liquid level detection function.

[0099] Embodiment 7

[0100] Based on the above embodiments, the present application further provides an MCU liquid level sensor. Refer to Figure 8 as shown. Figure 8Schematic block diagram of the MCU liquid level sensor provided in Embodiment 7 of this application. The MCU liquid level sensor includes a power supply, an MCU chip 900, and a plurality of detection circuits electrically connected to the MCU chip 900. The power supply is used to supply power to the MCU chip and the detection circuits. Each detection circuit includes the power supply circuit and the sensing circuit described in any of the above embodiments. The MCU chip 900 is detachably mounted on the ink cartridge. Among them, the detection circuits composed of the power supply circuit and the sensing circuit are sequentially arranged at intervals along the height extension direction of the ink cartridge on the inner wall of the ink storage chamber of the ink cartridge, and a plurality of detection circuits are arranged at different heights on the inner wall of the ink storage chamber. The MCU chip 900 can control the switching of the selection circuit in the power supply circuit to realize the switching of different functions such as heating or liquid level detection, and can also determine the medium environment where the detection circuit is located based on the voltage output by the power supply circuit, the voltage output by the sensing circuit, and the heating information of the diode circuit in the detection circuit, and then determine the liquid level information where the detection circuit is located.

[0101] Optionally, the MCU liquid level sensor may further include a calculation circuit 901. The calculation circuit 901 is electrically connected to the MCU chip 900 and the detection circuits respectively. The calculation circuit 901 calculates the data detected by the plurality of power supply circuits and sensing circuits. Through the multiplexer connected to the calculation circuit 901, the MCU chip sets the selected channel and outputs the corresponding signal to the analog-to-digital conversion circuit (ADC), and then outputs the corresponding digital signal to the MCU chip 900.

[0102] Specifically, the MCU chip can control the heating and detection of the above detection circuit based on the control signal of the printer.

[0103] Embodiment 8

[0104] Based on the above embodiments, this application also provides an ink cartridge. Refer to Figure 9 as shown Figure 9 Schematic block diagram of the ink cartridge provided in Embodiment 8 of this application. The ink cartridge includes a cartridge body and the sensor circuit described in any of Embodiments 1-6. The cartridge body is provided with an ink storage chamber for storing ink liquid. A plurality of detection circuits composed of a power supply circuit and a sensing circuit are arranged at different heights on the inner wall of the ink storage chamber. The ink liquid is heated by the heat generated by the diode circuit, and the signals output by the power supply circuit and the sensing circuit are used to detect the ink liquid level.

[0105] Specifically, the control circuit 1000, the power supply, the multiplexer and the analog-to-digital converter (ADC) in the computing circuit 1001 are respectively arranged in the box body. The control circuit is used to control the power supply to provide power for different power circuits and sensor circuit groups, and at the same time, it can control the switching of the selection circuit in the power circuit to realize the switching of different functions such as heating or liquid level detection. The data tested by multiple power circuits and sensor circuits are transmitted to the analog-to-digital converter through the multiplexer. The analog-to-digital converter converts the received signal into a digital signal and outputs the digital signal to the control circuit, so that the control circuit can control the operation of the detection circuit according to the digital signal.

[0106] Furthermore, the temperature is determined according to the heat generation of the diode, the corresponding ratio u1 is determined according to the temperature, and the ratio u2 calculated from the ratio of the pressure difference △VB and the output voltage Vref is used to determine the medium environment. The liquid level information can be measured according to multiple sensor circuits. For example, the height of the ink cartridge to be measured is h, and 2 sensor circuits are designed at equal intervals. When it is detected that both sensor circuits are in the ink medium, it can be judged that the liquid level is above 2 / 3h of the ink cartridge to be measured; when it is detected that the lower sensor circuit is in the ink medium and the upper sensor circuit is in the air medium, it can be judged that the liquid level is between 1 / 3h and 2 / 3h of the ink cartridge to be measured; when it is detected that both sensor circuits are in the air medium, it can be judged that the liquid level is below 1 / 3h of the ink cartridge to be measured.

[0107] The above is only the preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A sensor circuit for heating a liquid or detecting a liquid level; characterized in that, Comprising: A power supply circuit, the power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit and a cascaded circuit, the comparator and the heating branch are respectively connected to the cascaded circuit, and the diode circuit is electrically connected to the selection circuit; A control circuit, the control circuit is electrically connected to the selection circuit and is used to control the operation of the selection circuit so that the diode circuit is directly electrically connected to the cascaded circuit or electrically connected to the heating branch; A sensing circuit, the sensing circuit is electrically connected to the cascaded circuit and is used to output a liquid level signal of the liquid; Wherein, the cascaded circuit includes a first-level circuit, a second-level circuit and a third-level circuit connected in parallel. The first-level circuit includes a MOS transistor Q1, a resistor R1 and a diode D0. The second-level circuit includes a MOS transistor Q2, a resistor R2 and a resistor R3. The third-level circuit includes a MOS transistor Q3, a resistor R4, a voltage output interface and a current output interface. The voltage output interface is used to output a voltage Vref, and the current output interface is used to provide an output current Iref to the sensing circuit.

2. The sensor circuit according to claim 1, wherein The comparator is electrically connected to the first-level circuit, the second-level circuit and the third-level circuit respectively, and controls the states of the first-level circuit, the second-level circuit and the third-level circuit by the magnitude of the voltage input to the comparator. The sensing circuit is electrically connected to the third-level circuit, and the diode circuit is directly electrically connected to the second-level circuit or electrically connected to the heating branch.

3. The sensor circuit according to claim 2, wherein The third-level circuit includes a current output interface and a voltage output interface. The sensing circuit includes a first sensing diode branch, a second sensing diode branch and an amplifying circuit. The first sensing diode branch and the second sensing diode branch are connected in parallel, and the first sensing diode branch is connected to the current output interface. The amplifying circuit is connected between the first sensing diode branch and the second sensing diode branch.

4. The sensor circuit according to claim 2, wherein The heating branch is electrically connected to the third-level circuit. The selection circuit includes a second selection circuit. The diode circuit is electrically connected to the second selection circuit. The control circuit is electrically connected to the second selection circuit and is used to control the second selection circuit to be connected to the second-level circuit or electrically connected to the heating branch.

5. The sensor circuit according to claim 2, wherein The heating branch is electrically connected to the second-level circuit. The selection circuit includes a first selection circuit. The diode circuit is electrically connected to the first selection circuit. The control circuit is electrically connected to the first selection circuit and is used to control the first selection circuit to be directly electrically connected to the second-level circuit or electrically connected to the heating branch.

6. The sensor circuit according to claim 5, characterized in that, The second-level circuit further includes a current mirror circuit. The resistor R2 and the resistor R3 are connected in parallel and then electrically connected to the current mirror circuit. The heating branch is connected in parallel to the resistor R2. The control circuit is used to control the first selection circuit to be electrically connected to the heating branch or the resistor R2.

7. An MCU liquid level sensor is applied to the liquid level detection of a cavity, and is characterized in that It includes an MCU chip and multiple detection circuits. The detection circuits include a power supply circuit and a sensing circuit. The multiple detection circuits are respectively arranged at different heights in the cavity. The MCU chip is electrically connected to each detection circuit, used to control the heating or liquid level measurement of each detection circuit, and determine the medium environment where the detection circuit is located according to the signal output by the detection circuit, so as to determine the liquid level. Among them, the power supply circuit includes a comparator, a heating branch, a diode circuit, a selection circuit and a cascade circuit. The comparator and the heating branch are respectively connected to the cascade circuit. The diode circuit is electrically connected to the selection circuit. The selection circuit is controlled by the MCU chip to work, so as to switch the diode circuit to be electrically connected to the heating branch or directly electrically connected to the cascade circuit. The sensing circuit is electrically connected to the cascade circuit and is used to output the liquid level signal. Among them, the cascade circuit includes a first-level circuit, a second-level circuit and a third-level circuit connected in parallel. The first-level circuit includes a MOS transistor Q1, a resistor R1 and a diode D0. The second-level circuit includes a MOS transistor Q2, a resistor R2 and a resistor R3. The third-level circuit includes a MOS transistor Q3, a resistor R4, a voltage output interface and a current output interface. The voltage output interface is used to output a voltage Vref, and the current output interface is used to provide an output current Iref to the sensing circuit.

8. The MCU liquid level sensor according to claim 7, wherein The MCU liquid level sensor further includes a calculation circuit. The calculation circuit is electrically connected to the detection circuit and the MCU chip respectively, and is used to convert the signal output by the detection circuit into a digital signal and input it into the MCU chip.

9. An ink cartridge, characterized in that, It includes a box body and the sensor circuit according to any one of claims 1 to 6. The sensor circuit is detachably arranged in the box body.

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