Key signal identification circuit based on triode control

Abstract

The utility model discloses a button signal identification circuit based on triode control, which relates to the field of button signal identification, and is characterized in that each button is associated with a voltage dividing unit through a corresponding triode, and the triode controls the corresponding voltage dividing unit to work according to the state of the button, so that when the button is pressed down, the voltage dividing unit can be adjusted according to the state of the button. The corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key; that is to say, the key does not directly participate in the voltage division loop, but indirectly influences the voltage output in the circuit by controlling the conduction state of the triode, so that the state identification of the key does not depend on the contact impedance between the golden finger and the conductive rubber any more, and the condition that the key cannot be damaged even under the condition that the fluctuation of the contact impedance is large is ensured. And the circuit can accurately identify the key state without generating false triggering.

Description

TECHNICAL FIELD

[0001] The utility model relates to the key signal identification field especially, it relates to a key signal identification circuit based on triode control. BACKGROUND

[0002] At present, the key in the automobile electronic equipment generally adopts the process design of gold finger plus conductive rubber. According to the specific application scene and cost consideration, this process can be divided into multiple types, such as " carbon film + carbon particle " and " gold + nickel particle ". Among them, the combination of " carbon film + carbon particle " is widely applied due to its lower cost. However, this low-cost scheme has a significant problem: the variation range of contact impedance is large. In the light pressing state, due to the incomplete contact between the gold finger and the conductive rubber, the contact impedance can reach the level of KΩ (Kilo-Ohm) ; while in the heavy pressing state, when the contact is complete, the impedance is reduced to the level of Ω (Ohm). This impedance variation brings challenges to signal acquisition, especially when using an analog-digital converter (AD port) to detect the state of multiple keys, if the MCU supply voltage is 3.3V, the false touch phenomenon is prone to occur.

[0003] The utility model aims at solving the above-mentioned problem, that is, under the premise of not changing the existing " carbon film + carbon particle " process, not increasing additional AD acquisition port or replacing IO port matrix scanning, optimizing the reliability of the existing system. Specifically, the goal is to avoid the problem of AD port false signal acquisition caused by the excessive impedance error range of gold finger carbon film. By introducing an innovative circuit design scheme, the triode is used to control the voltage division unit of the key, so that the state recognition of each key is no longer dependent on the change of contact impedance, thereby ensuring that the system can accurately recognize the key state even in the case of large contact impedance fluctuation, without false triggering. This method not only maintains the cost advantage of the original design, but also significantly improves the stability and reliability of the system. SUMMARY

[0004] In order to make the state recognition of each key no longer dependent on the change of contact impedance, thereby ensuring that the system can accurately recognize the key state even in the case of large contact impedance fluctuation, without false triggering, the utility model provides a key signal recognition circuit based on triode control, comprising:

[0005] One or more keys;

[0006] One or more voltage division units, which correspond one-to-one to the one or more keys;

[0007] Triodes corresponding one-to-one to the one or more keys;

[0008] Each of the keys is associated with a voltage dividing unit through its corresponding transistor, and the transistor controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key.

[0009] Further, the key signal recognition circuit further comprises a common voltage dividing resistor; each of the voltage dividing units comprises a voltage dividing resistor; and the voltage dividing unit is composed of the voltage dividing resistor and the common voltage dividing resistor.

[0010] Further, one end of the key is connected to a positive power supply, and the other end is connected to the base of the corresponding transistor; the collector of the transistor is connected to the corresponding voltage dividing unit, and the emitter is grounded.

[0011] Further, when the key is pressed, the voltage dividing unit receives the key signal through the base of the transistor to make the transistor conductive, and then makes the positive power supply flow into the voltage dividing circuit formed by the corresponding voltage dividing resistor and the common voltage dividing resistor through the collector of the transistor, thereby dividing the positive power supply and generating a voltage signal corresponding to the key.

[0012] Further, in the voltage dividing unit:

[0013] One end of the voltage dividing resistor is connected to the collector of the corresponding transistor, and the other end is connected to one end of the common voltage dividing resistor; the other end of the common voltage dividing resistor is grounded.

[0014] Further, in the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

[0015] The utility model further provides a key signal recognition circuit based on transistor control, which comprises:

[0016] A plurality of keys;

[0017] A plurality of voltage dividing units, which correspond to the keys one by one;

[0018] N transistors; wherein N represents the difference obtained by subtracting 1 from the total number of keys;

[0019] Among them:

[0020] One of the keys is directly connected to the voltage dividing unit with the maximum voltage dividing value, and the remaining keys are connected to the corresponding voltage dividing units through a transistor;

[0021] For the keys connected through the transistor, the transistor controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the voltage dividing unit outputs a voltage signal corresponding to the key;

[0022] For the key directly connected to the voltage dividing unit, when the key is pressed, the voltage dividing unit outputs a voltage signal corresponding to the key.

[0023] Further, the key signal recognition circuit further comprises a common voltage dividing resistor; each of the voltage dividing units comprises a voltage dividing resistor; and the voltage dividing unit is composed of the voltage dividing resistor and the common voltage dividing resistor.

[0024] Further, for the key directly connected to the voltage dividing unit, one end of the key is grounded, and the other end is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit.

[0025] For the key connected through a triode, one end of the key is connected to a positive power supply, and the other end is connected to the base of the corresponding triode; the collector of the triode is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit; and the emitter is grounded.

[0026] The other end of the voltage dividing resistor is connected to one end of the common voltage dividing resistor; and the other end of the common voltage dividing resistor is connected to the positive power supply.

[0027] Further, in the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

[0028] Compared with the prior art, the utility model at least has the following beneficial effects:

[0029] (1) In the utility model, each key is associated with a voltage dividing unit through the corresponding triode; the triode controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key; that is, the key in the utility model does not directly participate in the voltage dividing circuit, but indirectly affects the voltage output in the circuit by controlling the conduction state of the triode, so that the state recognition of the key is no longer dependent on the contact impedance between the golden finger and the conductive rubber, ensuring that the circuit can accurately recognize the key state without false triggering even in the case of large contact impedance fluctuation.

[0030] (2) In order to improve the accuracy of key signal recognition, it is usually necessary to increase additional hardware resources such as more AD acquisition ports or replace the IO port matrix scanning, which will increase the cost, and the utility model does not need to change the existing "carbon film + carbon particle" process, nor does it need to increase additional AD acquisition ports or replace the IO port matrix scanning; by optimizing the circuit design, only a small amount of additional elements (such as triodes and resistors) are needed to realize high-precision key signal recognition, maintaining the cost advantage of the original design.

[0031] (3) This utility model adopts a simple and effective circuit design and uses a transistor to control the voltage divider unit so that each button can generate an independent and stable voltage signal for the MCU to recognize. This design not only simplifies the circuit structure, but also improves the stability and reliability of the circuit, ensuring that the button status can be accurately identified under various operating conditions.

[0032] (4) This utility model solves the problem of false triggering caused by large changes in contact impedance in the prior art through innovative circuit design, while maintaining the advantage of low cost, simplifying circuit design, and improving the stability and reliability of the circuit. Attached Figure Description

[0033] Figure 1 This is a circuit diagram of a key signal recognition circuit based on transistor control according to an embodiment of the present invention;

[0034] Figure 2 This is a circuit diagram of a key signal recognition circuit based on transistor control, which is another embodiment of this utility model. Detailed Implementation

[0035] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0036] Example 1

[0037] To ensure that the status recognition of each button no longer depends on changes in contact impedance, thus guaranteeing accurate button status recognition even under conditions of large contact impedance fluctuations and preventing false triggering, such as... Figure 1 As shown, this utility model proposes a key signal recognition circuit based on transistor control, comprising:

[0038] One or more buttons;

[0039] One or more voltage divider units, each corresponding to one or more buttons;

[0040] The key signal recognition circuit further includes a common voltage divider resistor; each voltage divider unit includes a voltage divider resistor; the voltage divider unit is composed of the voltage divider resistor and the common voltage divider resistor.

[0041] Specifically, such as Figure 1 As shown, voltage divider resistor R2 and common voltage divider resistor R1 form a voltage divider unit, voltage divider resistor R3 and common voltage divider resistor R1 form another voltage divider unit, and so on.

[0042] A transistor corresponding to one or more of the buttons;

[0043] Each of the keys is associated with a voltage dividing unit through its corresponding transistor, and the transistor controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key.

[0044] One end of the key is connected to the positive power supply, and the other end is connected to the base of the corresponding transistor, the collector of the transistor is connected to the corresponding voltage dividing unit, and the emitter is grounded.

[0045] In the voltage dividing unit:

[0046] One end of the voltage dividing resistor is connected to the collector of the corresponding transistor, and the other end is connected to one end of the common voltage dividing resistor; the other end of the common voltage dividing resistor is grounded.

[0047] In the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

[0048] The voltage dividing unit is used to receive the key signal through the base of the transistor when the key is pressed to make the transistor conductive, and then the positive power supply flows into the voltage dividing circuit formed by the corresponding voltage dividing resistor and the common voltage dividing resistor through the collector of the transistor, thereby dividing the voltage of the positive power supply and generating a voltage signal corresponding to the key.

[0049] It should be noted that the key actually includes a complete set of components such as physical keys, gold fingers, and conductive rubber. When the user presses the key, it actually triggers a change in the circuit by changing the contact state between the conductive rubber and the gold finger.

[0050] In the traditional design, the key directly participates in the voltage dividing circuit, which means that any change in contact impedance will directly affect the voltage dividing result. In the design of the present application, the key does not directly participate in the voltage dividing circuit, but indirectly affects the voltage output in the circuit by controlling the conduction state of the transistor.

[0051] Specifically, when a key (e.g. SW1) is pressed, the key will activate the corresponding transistor (e.g. TR1). The transistor acts as a switch to control the grounding of a specific resistor according to the state of the key. For example, when SW1 is pressed, TR1 is turned on, making R2 grounded through TR1, forming a voltage dividing circuit. In this voltage dividing circuit, the actual voltage division is completed by fixed resistors (R1 and R2), not by the contact impedance of the key itself. That is, since the key does not directly participate in the voltage dividing circuit, but controls the grounding of the resistor through the transistor, the voltage dividing value mainly depends on the resistance value of the fixed resistor, not the change of the contact impedance.

[0052] For example, assuming that SW1 is pressed, TR1 is turned on, and R2 is grounded through TR1. At this time, the positive power supply (VCC) forms a voltage dividing circuit through R1 and R2, and the output voltage signal is:

[0053]

[0054] Therefore, even in the case of light pressing or heavy pressing, the contact impedance between the gold finger and the conductive rubber changes greatly, but since the key does not directly participate in the voltage dividing circuit, these changes will not significantly affect the voltage value output to the MCU.

[0055] In addition, it should be noted that in order to further ensure that the voltage dividing value generated by each key is unique and stable, different resistance values are usually selected in the circuit design, so that the voltage dividing value generated by each key when pressed is significantly different.

[0056] In the utility model, each key is associated with a voltage dividing unit through its corresponding triode, and the triode controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key. That is, the key in the utility model does not directly participate in the voltage dividing circuit, but indirectly affects the voltage output in the circuit by controlling the conduction state of the triode, so that the state recognition of the key is no longer dependent on the contact impedance between the gold finger and the conductive rubber, ensuring that the circuit can accurately recognize the key state even in the case of large contact impedance fluctuations, without false triggering.

[0057] Embodiment two

[0058] As shown in Figure 2 The utility model also proposes a key signal recognition circuit based on triode control, which comprises:

[0059] A plurality of keys;

[0060] A plurality of voltage dividing units, which correspond one-to-one to the keys;

[0061] The key signal recognition circuit further comprises a common voltage dividing resistor; each voltage dividing unit comprises a voltage dividing resistor; and the voltage dividing unit is composed of the voltage dividing resistor and the common voltage dividing resistor.

[0062] N triodes; wherein N represents the difference between the total number of keys and 1;

[0063] Wherein:

[0064] One of the keys is directly connected to the voltage dividing unit with the largest voltage dividing value, and the remaining keys are connected to their corresponding voltage dividing units through a triode.

[0065] For the key connected through a transistor, the transistor controls the working of the corresponding voltage dividing unit according to the state of the key, and when the key is pressed, the voltage dividing unit outputs a voltage signal corresponding to the key;

[0066] For the key directly connected to the voltage dividing unit, when the key is pressed, the voltage dividing unit outputs a voltage signal corresponding to the key.

[0067] For the key directly connected to the voltage dividing unit, one end of the key is connected to the ground, and the other end is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit;

[0068] For the key connected through a transistor, one end of the key is connected to the positive power supply, and the other end is connected to the base of the corresponding transistor, the collector of the transistor is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit, and the emitter is connected to the ground;

[0069] The other end of the voltage dividing resistor is connected to one end of the common voltage dividing resistor, and the other end of the common voltage dividing resistor is connected to the positive power supply.

[0070] In the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

[0071] The difference between this embodiment and Embodiment One is that in this embodiment, one key is not connected to the voltage dividing unit through a transistor.

[0072] Specifically, this key is directly connected to the voltage dividing unit with the largest voltage dividing value, and the remaining keys are connected to their corresponding voltage dividing units through a transistor.

[0073] For the key directly connected to the voltage dividing unit (e.g. SW3), one end of the key is connected to the ground, and the other end is connected to one end of the voltage dividing resistor (e.g. R4) in the corresponding voltage dividing unit. When the key is pressed, due to the high resistance value (R4 has a large resistance value), even if there is a change in contact impedance, it will not significantly affect the final voltage value output to the MCU (Key ANI represents the pin output to the MCU). Figure 2 Therefore, this design can ensure that the recognition of the key state is still accurate and stable under light or heavy pressing. For the key connected through a transistor (e.g. SW1, SW2, etc.), each key controls a specific resistor to be grounded through its corresponding transistor. This design ensures that the key state can be accurately recognized even in the case of a large change in contact impedance. By reasonably selecting the resistance values, the voltage dividing value generated by each key when pressed can be significantly distinguished, facilitating accurate recognition by the MCU.

[0074] In addition, omitting a triode not only simplifies the circuit design, but also reduces the hardware cost. Considering that the price of a triode is relatively low, but for mass production, reducing a triode still brings certain cost savings, while not affecting the overall performance and reliability of the circuit.

[0075] In summary, the embodiment optimizes the circuit design, maintains the high reliability and stability of the system, and effectively controls the cost, especially suitable for cost-sensitive application scenarios.

[0076] In addition, it should be noted that other keys in the embodiment do not use triodes like SW3 to omit triodes by setting a large resistance value of the voltage dividing resistor because:

[0077] If all the keys use very high resistance values to avoid the influence of contact resistance, the voltage dividing values they produce will be very close to the power supply voltage (Vcc), which will reduce the voltage difference between different keys. For example, assuming R4 is 50kΩ and Vcc is 3.3V, the output voltage when SW3 is pressed is close to 3.3V. If other keys also use similar high resistance values, their output voltages will also be very close to 3.3V, making it difficult for the MCU to distinguish different key states. At the same time, higher resistance values mean smaller current in the circuit, which, although helps to reduce power consumption, may also cause insufficient signal strength or slow response speed. Especially in application scenarios that require fast response, too high resistance values may affect the overall performance of the circuit. The utility model uses a triode to control the grounding of the resistor, which can more flexibly adjust the voltage dividing value corresponding to each key, ensuring that even in the case of lower resistance, sufficient voltage difference can be obtained for identifying different key states.

[0078] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0079] In addition, the descriptions such as "first", "second", "one" and the like in the present application are only for descriptive purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0080] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, can be internal communication of two elements or interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0081] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the protection scope required by the present application.

Claims

1. A key signal recognition circuit based on triode control, characterized by, The key signal recognition circuit comprises: one or more keys; one or more voltage dividing units corresponding to the one or more keys; a triode corresponding to each of the one or more keys; each of the keys is associated with a voltage dividing unit through its corresponding triode, and the triode controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the corresponding voltage dividing unit can generate and output a voltage signal corresponding to the key.

2. The key signal recognition circuit based on triode control according to claim 1, characterized in that, The key signal recognition circuit further comprises a common voltage dividing resistor; each of the voltage dividing units comprises a voltage dividing resistor; and the voltage dividing units are composed of the voltage dividing resistors and the common voltage dividing resistor.

3. The key signal recognition circuit based on triode control according to claim 2, characterized in that One end of the key is connected to a positive power supply, and the other end is connected to the base of the corresponding triode; the collector of the triode is connected to the corresponding voltage dividing unit; and the emitter is grounded.

4. The key signal recognition circuit based on triode control according to claim 3, characterized in that, The voltage dividing unit is used to receive the key signal through the base of the triode when the key is pressed to make the triode conductive, so that the positive power supply flows into the voltage dividing circuit formed by the corresponding voltage dividing resistor and the common voltage dividing resistor through the collector of the triode, thereby dividing the voltage of the positive power supply and generating and outputting a voltage signal corresponding to the key.

5. The key signal recognition circuit based on triode control according to claim 4, characterized in that, In the voltage dividing unit: One end of the voltage dividing resistor is connected to the collector of the corresponding triode, and the other end is connected to one end of the common voltage dividing resistor; the other end of the common voltage dividing resistor is grounded.

6. A key signal recognition circuit based on triode control according to claim 5, characterized in that, In the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

7. A key signal recognition circuit based on triode control, characterized by, The key signal recognition circuit comprises: a plurality of keys; a plurality of voltage dividing units corresponding to the keys; N triodes; wherein N represents the difference between the total number of keys and 1; wherein: one of the keys is directly connected to the voltage dividing unit with the largest voltage dividing value, and the remaining keys are connected to their corresponding voltage dividing units through a triode; for the keys connected through the triode, the triode controls the operation of the corresponding voltage dividing unit according to the state of the key, so that when the key is pressed, the voltage dividing unit outputs a voltage signal corresponding to the key; for the keys directly connected to the voltage dividing unit, the voltage dividing unit outputs a voltage signal corresponding to the key when the key is pressed.

8. The key signal recognition circuit based on triode control according to claim 7, characterized in that, The key signal recognition circuit further comprises a common voltage dividing resistor; each of the voltage dividing units comprises a voltage dividing resistor; and the voltage dividing units are composed of the voltage dividing resistors and the common voltage dividing resistor.

9. The key signal recognition circuit based on triode control according to claim 8, wherein: for the keys directly connected to the voltage dividing unit, one end of the key is grounded, and the other end is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit; for the keys connected through the triode, one end of the key is connected to a positive power supply, and the other end is connected to the base of the corresponding triode; the collector of the triode is connected to one end of the voltage dividing resistor in the corresponding voltage dividing unit; and the emitter is grounded; the other end of the voltage dividing resistor is connected to one end of the common voltage dividing resistor; and the other end of the common voltage dividing resistor is connected to the positive power supply.

10. The transistor-controlled key signal recognition circuit according to claim 9, wherein In the voltage dividing unit, the connection end of the voltage dividing resistor and the common voltage dividing resistor is the output end of the voltage signal.

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