Refrigerator illumination control circuit and refrigerator

Abstract

The utility model discloses a refrigerator illumination control circuit and a refrigerator, and the refrigerator illumination control circuit comprises a door control switch which emits a conduction signal when a refrigerator door body is opened; the night mode switch sends out a conduction signal when the refrigerator is in a night mode; the control end of the switching circuit is respectively connected with the output end of the door control switch and the output end of the night mode switch; the power supply end of the square wave generating circuit is connected with a direct-current power supply through a switching path of the switching circuit, and the output end of the square wave generating circuit outputs a square wave signal; and the driving circuit is used for receiving the square wave signal output by the square wave generating circuit and driving an illuminating lamp to operate. According to the refrigerator illumination control circuit of the utility model, the square wave generating circuit generates the square wave signal, and the PWM signal can be generated without occupying the MCU resource, and therefore, the technical problem in the prior art that the MCU generates the PWM signal to the illumination lamp driving circuit can be solved, and the technical difficulty of generating the PWM signal can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and in particular to a refrigerator lighting control circuit and a refrigerator. Background Art

[0002] The internal lighting dimming function of existing refrigerators is to provide eye-friendly internal lighting of the refrigerator when a user opens the refrigerator door.

[0003] At night, there is insufficient light outside the refrigerator. If the user opens the refrigerator at this time, the light source inside the refrigerator is too bright and will cause discomfort to the human eyes.

[0004] The existing refrigerator internal lighting adjustment function is mostly achieved by the MCU on the main control board outputting a PWM signal to the LED drive circuit.

[0005] The MCU on the main control board outputs a PWM signal to the LED drive circuit, and the MCU adjusts the duty cycle of the PWM signal to achieve the dimming function.

[0006] The disadvantage of this type of solution is that it occupies MCU resources and must be set through software so that the MCU can output a PWM signal to achieve the dimming function, which increases the difficulty of dimming. Summary of the invention

[0007] The utility model provides a refrigerator lighting control circuit, which solves the technical problem in the prior art that an MCU generates a PWM signal for a lighting lamp driving circuit.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] The utility model provides a refrigerator lighting control circuit, comprising:

[0010] A door control switch that sends a conduction signal when the refrigerator door is opened;

[0011] a night mode switch that sends a conduction signal when the refrigerator is in night mode;

[0012] A switch circuit, a control end of which is respectively connected to the output end of the gate-controlled switch and the output end of the night mode switch;

[0013] A square wave generating circuit, whose power supply end is connected to a DC power supply through a switch path of the switch circuit, and whose output end outputs a square wave signal;

[0014] The driving circuit receives the square wave signal output by the square wave generating circuit and drives the lighting lamp to operate.

[0015] In some embodiments of the present application, the switch circuit includes a first switch tube and a second switch tube;

[0016] The control end of the first switch tube is respectively connected to the output end of the gate-controlled switch and the output end of the night mode switch; one end of the first switch tube is connected to the control end of the second switch tube, and the other end of the first switch tube is grounded;

[0017] The DC power supply is connected to the control end of the second switch tube through a first voltage divider circuit, one end of the switch path of the second switch tube is connected to the DC power supply, and the other end of the switch path of the second switch tube is connected to the power supply end of the square wave generating circuit.

[0018] In some embodiments of the present application, the night mode switch includes a third switch tube;

[0019] The control end of the third switch tube is connected to the main control unit;

[0020] One end of the switch path of the third switch tube is connected to a DC power supply through a pull-up resistor; one end of the switch path of the third switch tube is connected to a control end of the switch circuit;

[0021] The other end of the switch path of the third switch tube is grounded.

[0022] In some embodiments of the present application, the square wave generating circuit includes a timing chip, a charging circuit, and a discharging circuit;

[0023] The VCC pin of the timing chip is connected to the RESET pin;

[0024] The VCC pin is connected to the other end of the switch path of the second switch tube;

[0025] The VCC pin is connected to one end of the charging circuit through a current limiting resistor, and the other end of the charging circuit is grounded through a charging capacitor;

[0026] The charging capacitor is connected to the DISCHARGE pin of the timing chip through the discharge circuit;

[0027] The TRIGGER pin and the THRESHOLD pin of the timing chip are grounded respectively through the charging capacitor C4;

[0028] The OUTPUT pin of the timing chip is connected to the driving circuit.

[0029] In some embodiments of the present application, the discharge circuit includes a discharge resistor and a third diode;

[0030] One end of the discharge resistor is connected to the charging capacitor, the other end of the discharge resistor is connected to the anode of the third diode, and the cathode of the third diode is connected to the DISCHARGE pin.

[0031] In some embodiments of the present application, the charging circuit includes a charging resistor and a fourth diode;

[0032] One end of the charging resistor is connected to the current limiting resistor, the other end of the charging resistor is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the charging capacitor.

[0033] In some embodiments of the present application, the output end of the gate-controlled switch is connected to the anode of the first diode, and the cathode of the first diode is connected to the control end of the switch circuit;

[0034] The output end of the night mode switch is connected to the anode of the second diode, and the cathode of the second diode is connected to the control end of the switch circuit.

[0035] In some embodiments of the present application, the output end of the gate-controlled switch and the output end of the night mode switch are connected to the control end of the switch circuit through a second voltage divider circuit.

[0036] In some embodiments of the present application, the refrigerator lighting control circuit further includes a human body sensor, and an output end of the human body sensor is connected to a control end of the switch circuit.

[0037] Based on the design of the above refrigerator lighting control circuit, the utility model provides a refrigerator, including the above refrigerator lighting control circuit.

[0038] The technical solution of the utility model has the following technical effects compared with the prior art: the refrigerator lighting control circuit and refrigerator of the utility model send a conduction signal when the refrigerator door is opened by designing the door control switch, and the night mode switch sends a conduction signal when the refrigerator is in the night mode. The door control switch and the night mode switch control the on and off of the switch circuit. When the switch path of the switch circuit is turned on, the DC power supply supplies power to the square wave generating circuit, and the square wave generating circuit outputs a square wave signal to the driving circuit, and the driving circuit drives the lighting lamp to operate. Therefore, the refrigerator lighting control circuit of the utility model generates a square wave signal by the square wave generating circuit, and does not need to occupy MCU resources to generate a PWM signal, which solves the technical problem of the MCU generating a PWM signal to the lighting lamp driving circuit in the prior art, and reduces the technical difficulty of generating a PWM signal.

[0039] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 This is a principle block diagram of an embodiment of the refrigerator lighting control circuit of the utility model;

[0042] Figure 2 This is the control schematic diagram of the refrigerator lighting control circuit;

[0043] Figure 3 A circuit schematic diagram of an embodiment of a refrigerator lighting control circuit;

[0044] Figure 4 A circuit diagram of an embodiment of a night mode switch;

[0045] Figure 5 A circuit schematic diagram of another embodiment of a night mode switch;

[0046] Figure 6 A circuit schematic diagram of an embodiment of a timing chip;

[0047] Figure 7 This is the pin diagram of the timing chip;

[0048] Figure 8 This is the output voltage waveform of the timing chip;

[0049] Fig. 9 A circuit schematic diagram of an embodiment of a driving circuit;

[0050] Fig.10 The present invention is a schematic block diagram of another embodiment of the refrigerator lighting control circuit. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0053] The terms "first", "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, 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 or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In the present utility model, unless otherwise clearly stipulated and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0056] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0057] Embodiment 1

[0058] The refrigerator lighting control circuit of this embodiment includes a door control switch, a night mode switch, a switch circuit, a square wave generating circuit, a driving circuit, etc. Figure 1 , Figure 2 shown.

[0059] The door control switch is used to detect the opening and closing of the refrigerator door and output an on / off signal. The door control switch sends an on signal when the refrigerator door is opened.

[0060] When the refrigerator door is opened, the door control switch is closed and outputs a low-level conduction signal.

[0061] When the refrigerator door is closed, the door control switch is turned on and a high-level shutdown signal is output.

[0062] A night mode switch that sends an on signal when the refrigerator is in night mode.

[0063] When the refrigerator is in night mode, the night mode switch is closed / turned on and outputs a low-level turn-on signal.

[0064] When the refrigerator is in non-night mode, the night mode switch is disconnected and outputs a high-level shutdown signal.

[0065] The switch circuit has a control end connected to the output end of the gate switch and the output end of the night mode switch. The gate switch and the night mode switch jointly control the on and off of the switch circuit. After both the gate switch and the night mode switch send a conduction signal, the switch circuit is turned on.

[0066] The square wave generating circuit has a power supply end connected to a DC power supply through a switch path of a switch circuit, and an output end outputs a square wave signal (PWM signal). When the switch path of the switch circuit is turned on, the power supply circuit of the square wave generating circuit is turned on, and the current provided by the DC power supply is transmitted to the power supply end of the square wave generating circuit through the switch path of the switch circuit to supply power to the square wave generating circuit.

[0067] The driving circuit is connected to the output end of the square wave generating circuit, receives the square wave signal output by the square wave generating circuit, and drives the lighting lamp to operate.

[0068] When the refrigerator door is opened and the refrigerator is in night mode, the door control switch and the night mode switch both send out a conduction signal, the switch path of the switch circuit is turned on, the DC power supply supplies power to the square wave generating circuit, the square wave generating circuit works, and outputs a PWM signal with a certain duty cycle to the drive circuit. The drive circuit drives the lighting lamp to light up according to the received square wave signal to adjust the brightness of the lighting inside the refrigerator.

[0069] The refrigerator lighting control circuit of this embodiment is designed to send a conduction signal when the door of the refrigerator is opened, and the night mode switch sends a conduction signal when the refrigerator is in night mode. The door control switch and the night mode switch control the on and off of the switch circuit. When the switch path of the switch circuit is turned on, the DC power supply supplies power to the square wave generating circuit, and the square wave generating circuit outputs a square wave signal to the driving circuit, and the driving circuit drives the lighting lamp to operate. Therefore, the refrigerator lighting control circuit of this embodiment generates a square wave signal by the square wave generating circuit, and does not need to occupy MCU resources to generate a PWM signal, which solves the technical problem of the MCU generating a PWM signal to the lighting lamp driving circuit in the prior art and reduces the technical difficulty of generating a PWM signal.

[0070] The refrigerator lighting control circuit of this embodiment does not require a light sensor to detect ambient light, and does not require a PWM controller and a single-chip microcomputer to provide a PWM signal. The PWM signal is provided to the drive circuit only through a hardware circuit, which reduces the difficulty of generating a PWM signal.

[0071] In some embodiments of the present application, the switch circuit includes a first switch tube N1 and a second switch tube N2. Figure 3 shown.

[0072] The control end of the first switch tube N1 is respectively connected to the output end of the gate switch and the output end of the night mode switch; one end of the first switch tube N1 is connected to the control end of the second switch tube N2, and the other end of the first switch tube N1 is grounded; the DC power supply is connected to the control end of the second switch tube N2 through the first voltage divider circuit, one end of the switch path of the second switch tube N2 is connected to the DC power supply, and the other end of the switch path of the second switch tube N2 is connected to the power supply end of the square wave generating circuit.

[0073] When the gate switch sends a turn-on signal and the night mode switch sends a turn-on signal, the first switch tube N1 is turned off, the second switch tube N2 is turned on, and the DC power supply (voltage is VCC) supplies power to the power supply end of the square wave generating circuit through the switch path of the second switch tube N2, and the square wave generating circuit outputs a square wave signal.

[0074] When the gate switch sends a shutdown signal or the night mode switch sends a shutdown signal, the first switch tube N1 is turned on and the second switch tube N2 is turned off, and the DC power supply cannot supply power to the power supply end of the square wave generating circuit.

[0075] The other end of the switch path of the second switch tube N2 is grounded through the electrolytic capacitor E1 and the filter capacitor C1 respectively.

[0076] By designing the switch circuit of the circuit structure, the first switch tube N1 and the second switch tube N2 are used to control the on and off of the power supply circuit of the square wave generating circuit, which is convenient to control and easy to implement.

[0077] In some embodiments of the present application, the first switch tube N1 and the second switch tube N2 are both high on-state voltage drop switch tubes.

[0078] For example, the first switch tube N1 and the second switch tube N2 are both NPN transistors. Figure 3 shown.

[0079] The base of the first switch tube N1 is connected to the output end of the gate-controlled switch and the output end of the night mode switch respectively; the collector of the first switch tube N1 is connected to the base of the second switch tube N2, and the emitter of the first switch tube N1 is grounded.

[0080] The first voltage divider circuit includes a resistor R3 and a resistor R4 connected in series, a DC power supply (voltage is VCC) is grounded through the first voltage divider circuit, and a voltage dividing node between the circuit R3 and the resistor R4 is connected to the base of the second switch tube N2. The collector of the second switch tube N2 is connected to the DC power supply, and the emitter of the second switch tube N2 is connected to the power supply end of the square wave generating circuit. The emitter of the second switch tube N2 is grounded through the electrolytic capacitor E1, and the emitter of the second switch tube N2 is grounded through the filter capacitor C1.

[0081] In some embodiments of the present application, the night mode switch includes a third switch tube N3, see Figure 4 shown.

[0082] The control end of the third switch tube N3 is connected to the main control unit through the current limiting resistor R9; the control end of the third switch tube N3 is grounded through the bias resistor R11; one end of the switch path of the third switch tube N3 is connected to the DC power supply through the pull-up resistor R10; one end of the switch path of the third switch tube N3 is connected to the control end of the switch circuit, and outputs a high level or low level signal to the control end of the switch circuit; the other end of the switch path of the third switch tube N3 is grounded.

[0083] In the night mode, the main control unit outputs a conduction signal to the control end of the third switch tube N3, the third switch tube N3 is turned on, and one end of the switch path of the third switch tube N3 outputs a low-level conduction signal.

[0084] In the non-night mode, the main control unit outputs a shutdown signal to the control end of the third switch tube N3, the third switch tube N3 is turned off, and one end of the switch path of the third switch tube N3 outputs a high-level shutdown signal.

[0085] The main control unit can know whether the refrigerator is in night mode based on the internal time signal.

[0086] By designing the above-mentioned night mode switch, the on and off of the night mode switch can be controlled by the main control unit, which is simple and convenient.

[0087] In some embodiments of the present application, the third switch tube N3 is a high conduction voltage drop switch tube, such as an NPN transistor, see Figure 4 shown.

[0088] In the night mode, the main control unit outputs a high-level conduction signal to the base of the third switch tube N3, the third switch tube N3 is turned on, and the collector of the third switch tube N3 outputs a low-level conduction signal.

[0089] In the non-night mode, the main control unit outputs a low-level shutdown signal to the base of the third switch tube N3, the third switch tube N3 is turned off, and the collector of the third switch tube N3 outputs a high-level shutdown signal.

[0090] In some other embodiments of the present application, the night mode switch includes a manual switch SB, see Figure 5 shown.

[0091] One end of the manual switch SB is connected to the DC power supply through a resistor, the other end of the manual switch SB is grounded, and one end of the manual switch SB is connected to the control end of the first switch tube N1 to output a high level or low level signal to the control end of the first switch tube N1.

[0092] The manual switch SB is closed, indicating that the refrigerator is in night mode, and one end of the manual switch SB is at a low level, that is, a low-level conduction signal is output.

[0093] The manual switch SB is disconnected, indicating that the refrigerator is in non-night mode, and one end of the manual switch SB is at a high level, that is, a high-level shutdown signal is output.

[0094] The manual switch SB has a simple structure and low cost.

[0095] In some embodiments of the present application, the square wave generating circuit includes a timing chip IC1 (such as NE555), a charging circuit, a discharging circuit, etc. Figure 3 , Figure 6 , Figure 7 shown.

[0096] The timing chip IC1 has a GND pin (pin 1), a TRIGGER pin (pin 2), an OUTPUT pin (pin 3), a RESET pin (pin 4), a CONTROL VOLTAGE pin (pin 5), a THRESHOLD pin (pin 6), a DISCHARGE pin (pin 7), and a VCC pin (pin 8).

[0097] The GND pin is grounded. The VCC pin (pin 8) is the power supply pin of the chip, and the VCC pin is connected to the RESET pin (pin 4).

[0098] The VCC pin is connected to the other end of the switch path of the second switch tube N2; the VCC pin is connected to one end of the charging circuit through the current limiting resistor R5, and the other end of the charging circuit is grounded through the charging capacitor C4.

[0099] The charging capacitor C4 is connected to the DISCHARGE pin through a discharge circuit; the TRIGGER pin and the THRESHOLD pin are grounded through the charging capacitor C4 respectively.

[0100] The OUTPUT pin is connected to the driving circuit through the resistor R8, and outputs a square wave signal to the driving circuit.

[0101] The OUTPUT pin is grounded through filter capacitor C3 to filter out high-frequency interference signals.

[0102] The CONTROLVOLTAGE pin is grounded through filter capacitor C2 to prevent the introduction of high-frequency interference.

[0103] When the VCC pin is connected to a DC power supply (voltage is VCC), the DC power supply charges the charging capacitor C4 through the path from R5 to the charging circuit.

[0104] The TRIGGER pin (pin 2) and the THRESHOLD pin (pin 6) of the timing chip IC1 detect the voltage of the charging capacitor C4.

[0105] When the voltage Uc of the charging capacitor C4 rises to 2 / 3VCC, the output voltage Uo of the OUTPUT pin (pin 3) is low, the discharge switch tube inside the timing chip IC1 is turned on, the charging of the charging capacitor C4 stops, and it starts to discharge through the discharge circuit → DISCHARGE pin (pin 7), thereby reducing the voltage Uc of the charging capacitor C4.

[0106] When the voltage Uc of the charging capacitor C4 drops to 1 / 3 VCC, the output voltage Uo of the OUTPUT pin (pin 3) changes from low level to high level. At this time, the discharge switch tube inside the chip IC1 is turned off, and the DC power supply starts to charge C4 again.

[0107] Repeat the above process, the OUTPUT pin (pin 3) outputs a continuous pulse waveform (PWM signal), which is then output to the drive circuit after passing through resistor R8. Figure 8 shown.

[0108] By designing the square wave generating circuit of the above structure, not only can the square wave signal be output stably, but also the circuit structure is simple, easy to build and low in cost.

[0109] In some embodiments of the present application, the discharge circuit includes a discharge resistor R6 and a third diode D3. One end of the discharge resistor R6 is connected to one end of the charging capacitor C4, and the other end of the charging capacitor C4 is grounded; the other end of the discharge resistor R6 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the DISCHARGE pin.

[0110] By designing the above-mentioned discharge circuit, not only the stable discharge of the charging capacitor C4 is achieved, but also the flow direction of the discharge current can be guaranteed.

[0111] In some embodiments of the present application, the charging circuit includes a charging resistor R7 and a fourth diode D4. One end of the charging resistor R7 is connected to the current limiting resistor R5, the other end of the charging resistor R7 is connected to the anode of the fourth diode D4, the cathode of the fourth diode D4 is connected to one end of the charging capacitor C4, and the other end of the charging capacitor C4 is grounded.

[0112] By designing the above charging circuit, not only can the charging capacitor C4 be stably charged, but the flow direction of the charging current can also be guaranteed.

[0113] In some embodiments of the present application, in order to ensure the flow of signals, the output end of the gate switch is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the control end of the switch circuit (specifically the base of the first switch tube N1).

[0114] In some embodiments of the present application, in order to ensure the flow of signals, the output end of the night mode switch is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the control end of the switch circuit (specifically the base of the first switch tube N1).

[0115] In some embodiments of the present application, in order to ensure the safety of the switching circuit and prevent large current from burning the switching circuit, the output end of the gate switch and the output end of the night mode switch are connected to the control end of the switching circuit through a second voltage divider circuit.

[0116] The second voltage divider circuit includes a resistor R1 and a resistor R2 connected in series.

[0117] One end of the resistor R1 is connected to the output end of the gate-controlled switch through the first diode D1;

[0118] One end of the resistor R1 is connected to the output end of the night mode switch through a second diode D2.

[0119] The other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R2 is grounded; the voltage dividing node between the circuit R1 and the resistor R2 is connected to the base of the first switch tube N1.

[0120] When one of the gate switch and the night mode switch outputs a high level, or both of them output a high level, that is, current flows through one of the diodes D1 and D2, or current flows through both of them, the transistor N1 is saturated and turned on, the transistor N2 is turned off, the timing chip IC1 has no power supply, and the square wave generating circuit does not work.

[0121] When the gate switch and the night mode switch output low level at the same time, that is, no current flows through diodes D1 and D2, transistor N1 is turned off, transistor N2 is saturated and turned on, the timing chip IC1 is powered by a DC power supply, and the timing chip IC1 works normally and outputs a PWM signal.

[0122] See also Figure 8 As shown, the duty cycle of the PWM signal output by the timing chip IC1 = tp1 / (tp1+tp2);

[0123] tp1≈0.7×(R5+R7)×C4;

[0124] tp2≈0.7×R6×C4;

[0125] Among them, 0.7 is an empirical coefficient, an approximate value, used to calculate the charge and discharge time of the capacitor.

[0126] Therefore, the duty cycle of the PWM signal = tp1 / (tp1+tp2) = (R5+R7) / (R5+R6+R7).

[0127] As can be seen from the above, the duty cycle of the PWM signal output by the timing chip IC1 is determined by the resistance values ​​of R5, R6, and R7. According to the actual dimming brightness requirements, select appropriate resistance values ​​and fix the duty cycle of the PWM signal to obtain the corresponding LED drive circuit output value.

[0128] The driving circuit includes a fourth switch tube N4, see Fig. 9 As shown, the control end of the fourth switch tube N4 is connected to the output end of the square wave generating circuit through the resistor R12, one end of the switch path of the fourth switch tube N4 is connected to the DC power supply, the other end of the switch path of the fourth switch tube N4 is grounded through the resistor R14, and the other end of the switch path of the fourth switch tube N4 is connected to the lighting lamp (LED).

[0129] The square wave generating circuit outputs a PWM signal to the control end of the fourth switch tube N4 to control the on and off of the fourth switch tube N4. When the fourth switch tube N4 is turned on, the current provided by the DC power supply flows to the lighting lamp LED to power the LED; when the fourth switch tube N4 is turned off, the DC power supply cannot power the LED.

[0130] The fourth switch tube N4 is a low on-state voltage drop switch tube, such as a PNP transistor.

[0131] In some other embodiments of the present application, the refrigerator lighting control circuit further includes a human body sensor, and the output end of the human body sensor is connected to the control end of the switch circuit (specifically the control end of the first switch tube N1), see Fig.10 shown.

[0132] The human body sensor is arranged on the front face of the refrigerator body and is used to detect whether there is a person in front of the refrigerator.

[0133] When there is someone in front of the refrigerator, the human body sensor detects the human body and outputs a low-level conduction signal.

[0134] When there is no one in front of the refrigerator, the human body sensor does not detect a human body and outputs a high-level shutdown signal.

[0135] Therefore, when the refrigerator door is open, the refrigerator is in night mode, and there is someone in front of the refrigerator, the door control switch, the night mode switch, and the human body sensor all send out conduction signals, the switch path of the switching circuit is turned on, the square wave generating circuit works, and the PWM signal is output to the drive circuit, which drives the internal light of the refrigerator to light up.

[0136] By providing the human body sensor, the light can be prevented from being on when there is no one in front of the refrigerator, thus saving electric energy.

[0137] The refrigerator lighting control circuit of this embodiment does not need to occupy MCU resources, and the dimming function of the refrigerator lighting (LED light) can be realized only through the hardware circuit.

[0138] The refrigerator lighting control circuit of this embodiment does not occupy the PWM output port of the main control unit (MCU), saving MCU resources; it also does not require software programming settings, eliminating the programming steps. The square wave generator circuit composed of the timing chip NE555 and its external devices outputs a PWM signal and provides it to the drive circuit to realize the dimming function.

[0139] Embodiment 2

[0140] Based on the design of the refrigerator lighting control circuit in the above-mentioned embodiment 1, this embodiment 2 proposes a refrigerator, including a refrigerator body, a refrigerator door, the refrigerator lighting control circuit, a lighting lamp, etc.

[0141] The refrigerator door is installed at the front end of the refrigerator body, and the refrigerator lighting control circuit is installed on the refrigerator body or the refrigerator door to control the operation of the lighting lamp.

[0142] The refrigerator of this embodiment, by designing a refrigerator lighting control circuit, generates a square wave signal by a square wave generating circuit, and does not need to occupy MCU resources to generate a PWM signal. This solves the technical problem of the prior art in which the MCU generates a PWM signal for the lighting lamp driving circuit, reduces the technical difficulty of generating a PWM signal, and improves the market competitiveness of the refrigerator.

[0143] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0144] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this. Any changes or substitutions that can be easily thought of by technicians familiar with the technical field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. Refrigerator lighting control circuit, characterized in that, include: A door control switch that sends a conduction signal when the refrigerator door is opened; a night mode switch that sends a conduction signal when the refrigerator is in night mode; A switch circuit, a control end of which is respectively connected to the output end of the gate-controlled switch and the output end of the night mode switch; A square wave generating circuit, whose power supply end is connected to a DC power supply through a switch path of the switch circuit, and whose output end outputs a square wave signal; The driving circuit receives the square wave signal output by the square wave generating circuit and drives the lighting lamp to operate.

2. The refrigerator lighting control circuit according to claim 1, characterized in that: The switch circuit includes a first switch tube and a second switch tube; The control end of the first switch tube is respectively connected to the output end of the gate-controlled switch and the output end of the night mode switch; one end of the first switch tube is connected to the control end of the second switch tube, and the other end of the first switch tube is grounded; The DC power supply is connected to the control end of the second switch tube through a first voltage divider circuit, one end of the switch path of the second switch tube is connected to the DC power supply, and the other end of the switch path of the second switch tube is connected to the power supply end of the square wave generating circuit.

3. The refrigerator lighting control circuit according to claim 1, characterized in that: The night mode switch includes a third switch tube; The control end of the third switch tube is connected to the main control unit; One end of the switch path of the third switch tube is connected to a DC power supply through a pull-up resistor; one end of the switch path of the third switch tube is connected to a control end of the switch circuit; The other end of the switch path of the third switch tube is grounded.

4. The refrigerator lighting control circuit according to claim 2, characterized in that: The square wave generating circuit includes a timing chip, a charging circuit, and a discharging circuit; The VCC pin of the timing chip is connected to the RESET pin; The VCC pin is connected to the other end of the switch path of the second switch tube; The VCC pin is connected to one end of the charging circuit through a current limiting resistor, and the other end of the charging circuit is grounded through a charging capacitor; The charging capacitor is connected to the DISCHARGE pin of the timing chip through the discharge circuit; The TRIGGER pin and the THRESHOLD pin of the timing chip are grounded respectively through the charging capacitor; The OUTPUT pin of the timing chip is connected to the driving circuit.

5. The refrigerator lighting control circuit according to claim 4, characterized in that: The discharge circuit includes a discharge resistor and a third diode; One end of the discharge resistor is connected to the charging capacitor, the other end of the discharge resistor is connected to the anode of the third diode, and the cathode of the third diode is connected to the DISCHARGE pin.

6. The refrigerator lighting control circuit according to claim 4, characterized in that: The charging circuit includes a charging resistor and a fourth diode; One end of the charging resistor is connected to the current limiting resistor, the other end of the charging resistor is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the charging capacitor.

7. The refrigerator lighting control circuit according to claim 1, characterized in that: The output end of the gate-controlled switch is connected to the anode of the first diode, and the cathode of the first diode is connected to the control end of the switch circuit; The output end of the night mode switch is connected to the anode of the second diode, and the cathode of the second diode is connected to the control end of the switch circuit.

8. The refrigerator lighting control circuit according to claim 1, characterized in that: The output end of the gate-controlled switch and the output end of the night-mode switch are connected to the control end of the switch circuit through a second voltage divider circuit.

9. The refrigerator lighting control circuit according to any one of claims 1 to 8, characterized in that: The refrigerator lighting control circuit also includes a human body sensor, and an output end of the human body sensor is connected to the control end of the switch circuit.

10. A refrigerator, characterized in that The invention comprises a refrigerator lighting control circuit as claimed in any one of claims 1 to 9.

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