Keyboard backlight circuit driving method

Abstract

The application discloses a keyboard backlight circuit driving method, which is executed by a keyboard backlight circuit integrated with a key detection function, the keyboard backlight circuit integrated with the key detection function comprises a plurality of scanning lines arranged at intervals and a plurality of output lines arranged at intervals, the plurality of output lines and the plurality of scanning lines are staggered to form a matrix circuit, the scanning lines are provided with light-emitting diodes for keyboard backlight, the output lines are provided with a plurality of switch circuits connected with the plurality of scanning lines respectively, and the switch circuits comprise key switches; the keyboard backlight circuit driving method comprises the following steps: A1. driving the light-emitting diodes to emit light as required in a first time period t10; A2. performing key detection in a second time period t11; and A3. repeating the step A1 and the step A2 in sequence. The keyboard backlight circuit driving method can realize keyboard backlight and key detection, and is beneficial to realize diversified light-emitting effects.

Description

TECHNICAL FIELD

[0001] The present application relates to an information input device, in particular to a keyboard backlight circuit driving method. BACKGROUND

[0002] With the development of technology, electronic devices are increasingly diversified. In order to realize human-computer interaction, electronic devices are usually provided with keys. For example, computers are usually equipped with keyboards to perform typing, gaming, and other operations.

[0003] In order to make the keyboard still convenient to use in dark or dim environment, some keyboards have backlight function. The keys or the areas around the keys are illuminated by LEDs (Light Emitting Diodes) so that the user can identify the positions of the keys on the keyboard and accurately perform key operations. The backlight function of the keyboard is realized by a keyboard backlight circuit. The keyboard backlight circuit is provided with light emitting diodes corresponding to the positions of the keys. The backlight function of the keyboard is realized by controlling the light emitting diodes to emit light.

[0004] Further, in order to receive the information of the keys, the keyboard is also provided with a key detection circuit to identify which key is pressed.

[0005] That is to say, for the keyboard with backlight function, the keyboard backlight circuit and the key detection circuit need to be arranged in the keyboard at the same time, which leads to complex circuit arrangement, multiple layers of circuit boards or the need for multiple circuit boards to be stacked, large thickness, and ultimately leads to large thickness and high cost of the keyboard.

[0006] For some products pursuing thinness, the complex circuit board design will make the overall circuit board too thick, which cannot meet the needs of thin and light notebook computers.

[0007] The above content is only used to help understand the technical solutions of the present application and does not constitute an acknowledgement of the above as prior art. SUMMARY

[0008] The purpose of the present application is to provide a keyboard backlight circuit driving method which can realize keyboard backlight and key detection at the same time.

[0009] To achieve the above-mentioned purpose, in a first aspect, the present application provides a keyboard backlight circuit driving method, which is executed by a keyboard backlight circuit integrated with key detection function. The keyboard backlight circuit integrated with key detection function includes a plurality of scanning lines arranged at intervals and a plurality of output lines arranged at intervals. The plurality of output lines and the plurality of scanning lines are staggered to form a matrix circuit. The scanning lines are provided with light emitting diodes for keyboard backlight. The output lines have a plurality of switch circuits connected to the plurality of scanning lines respectively. The switch circuit includes a key switch.

[0010] The keyboard backlight circuit driving method includes the following steps:

[0011] A1. Drive the LED to emit light as needed during the first time period t10;

[0012] A2. During the second time period t11, perform key press detection;

[0013] A3. Repeat steps A1 and A2 in sequence.

[0014] Furthermore, the first time period t10 and the second time period t11 form a light emission period T2, and the first time period t10 is greater than or equal to the second time period t11.

[0015] Furthermore, the time ratio of the first time period t10 to the light emission period T2 is not less than 80%, and the time ratio of the first time period t10 to the light emission period T2 is not greater than 99.9%.

[0016] Furthermore, in step A1, during the first time period, a driving voltage signal is input to the first voltage terminal of all the scan lines according to the control signal, so as to drive all the light-emitting diodes to continuously emit light or produce a lamp effect.

[0017] Furthermore, the duration of the second time period t11 is less than or equal to 41.6 ms.

[0018] Furthermore, the first time period t10 and the second time period t11 form a light emission period T2, the duration of the light emission period T2 is less than or equal to 41.6 ms, and the duration of the second time period t11 is less than or equal to 15 ms.

[0019] Further, in step A2, the key detection includes:

[0020] A21. A high level of a preset duration is sequentially applied to the first voltage terminal of a plurality of scan lines, and a high level is applied to the first voltage terminal of only one scan line at a time;

[0021] A22. During the period when the high level is applied, detect the voltage signal at the voltage output terminals of the multiple output lines and determine whether the voltage magnitude is within the preset amplitude range;

[0022] A23. When the magnitude of the voltage signal at a certain voltage output terminal is detected to be within a preset amplitude range, the triggered button switch is determined by combining the voltage conditions of the high-level scan line and the voltage output terminals of the multiple output lines.

[0023] Further, step A23 includes the following steps:

[0024] A231. When the magnitude of the voltage signal at the voltage output terminal of a certain output line is detected to be within a preset amplitude range, acquire the scan lines that are simultaneously supplied with a high level.

[0025] A232. Identify the push-button switch connected between a qualified output line and a scan line that is simultaneously supplied with a high level. This push-button switch is the triggered push-button switch. The qualified output line refers to the output line corresponding to the voltage output terminal where the magnitude of the detected voltage signal is within a preset amplitude range.

[0026] Furthermore, the scan line has a main line and multiple parallel branch lines connected to the main line. The main line has a first voltage terminal, and each branch line has a second voltage terminal, which is a ground voltage terminal. A light-emitting diode and a first resistor are connected in series between the connection point of the branch line and the main line and the second voltage terminal. The light-emitting diode causes current to flow unidirectionally towards the first resistor.

[0027] The output line has a voltage output terminal and multiple switching circuits that are respectively connected to branches of the multiple scan lines. Each branch is provided with a corresponding switching circuit, and the switching circuit is connected to the portion of the branch located between the light-emitting diode and the first resistor.

[0028] Furthermore, the switching circuit also includes a second resistor connected in series with the push-button switch.

[0029] Furthermore, the resistance of the second resistor is less than or equal to 10 times the resistance of the first resistor, and greater than or equal to 0.2 times the resistance of the first resistor.

[0030] Compared with the prior art, the present invention has the following beneficial effects: According to some embodiments of the present invention, by inserting a switch circuit in series into the keyboard backlight circuit, the keyboard backlight effect can be achieved while also realizing the function of key detection. At the same time, the light-emitting diode is driven to emit light as needed during the first time period t10; key detection is performed during the second time period t11. This can produce diverse lighting effects during the first time period t10, increasing aesthetics, while key detection during the second time period t11 does not affect the normal recognition of the keys. Attached Figure Description

[0031] Figure 1 This is a circuit diagram of a keyboard backlight circuit with integrated key detection function according to an embodiment of the present invention.

[0032] Figure 2 yes Figure 1 The diagram shown illustrates a circuit designed to prevent false detections.

[0033] Figure 3 This is a circuit diagram of a keyboard backlight circuit with integrated key detection function according to an embodiment of the present invention. In the diagram, the switching circuit is provided with a second resistor.

[0034] Figure 4 This is a timing diagram of applying a high-level signal to each scan line during key detection according to an embodiment of the present invention. The diagram shows two scan cycles.

[0035] Figure 5 This is a timing diagram of one emission cycle in one embodiment of the present invention.

[0036] Figure 6 This is a timing diagram of one emission cycle in one embodiment of the present invention.

[0037] Figure 7 This is a timing diagram of one emission cycle in one embodiment of the present invention.

[0038] Figure 8 This is a timing diagram of the energizing cycles of each scan line in one embodiment of the present invention.

[0039] Figure 9 This is a timing diagram of the energizing cycles of each scan line in one embodiment of the present invention.

[0040] Figure 10 This is a schematic diagram of the structure of a key input device according to an embodiment of the present invention.

[0041] Figure 11 This is a schematic diagram of the structure of a key input device according to an embodiment of the present invention. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0043] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] This invention proposes a keyboard backlight circuit (hereinafter referred to as the keyboard backlight circuit) with integrated key detection function, which can be used in keyboards or electronic devices with multiple keys. The keyboard backlight circuit can realize the backlight of the keyboard and also detect the keys, thereby determining which key of the device is pressed.

[0046] like Figure 1 As shown, a keyboard backlight circuit corresponding to one embodiment of the present invention includes multiple scan lines 10 and multiple output lines 11. The multiple scan lines 10 are arranged at intervals, and the multiple output lines 11 are also arranged at intervals, with the scan lines 10 and output lines 11 interleaved to form a matrix circuit. Figure 1 As shown, Figure 1 The number of scan lines 10 and output lines 11 shown are both 3. For ease of description, the three scan lines 10 from top to bottom are called the first scan line 10a, the second scan line 10b and the third scan line 10c, respectively, and the three output lines 11 from left to right are called the first output line 11a, the second output line 11b and the third output line 11c, respectively.

[0047] It should be noted that in this document, the terms "multiple," "more than," or similar expressions indicate a quantity of at least two; that is, "more" means two or more. Therefore, in other embodiments, the number of scan lines 10 and output lines 11 can be two or more than three. Furthermore, although the number of scan lines 10 and output lines 11 is the same in the illustrated embodiment, this is not mandatory. The number of scan lines 10 and output lines 11 can differ; for example, one may have two lines, and the other three, etc.

[0048] Scan line 10 has a first voltage terminal 100 and a second voltage terminal 101. The number of second voltage terminals 101 can be multiple, for example... Figure 1 In the illustrated embodiment, the scan line 10 includes a main line 102 and multiple branch lines 103 connected to the main line 102. The multiple branch lines 103 are arranged in parallel. Each branch line 103 is provided with a second voltage terminal 101. A light-emitting diode and a first resistor are sequentially arranged between the connection position of the branch line 103 and the main line 102 and the second voltage terminal 101. The light-emitting diode and the first resistor are connected in series. Figure 1D1 to D9, as marked, are LEDs, and R1 to R9 are the first resistors. The LEDs allow current to flow unidirectionally towards the second voltage terminal 101. That is, the current flowing through the first voltage terminal 100 flows into the positive terminal of the LED, then flows out from the negative terminal and through the first resistor, causing the LED to emit light. It is understandable that due to the unidirectional conduction characteristic of the LED, current cannot flow from its negative terminal to its positive terminal.

[0049] The output line 11 has a voltage output terminal 110 and multiple switch circuits 12 connected to multiple scan lines 10 respectively. Specifically, the multiple switch circuits 12 are connected to branches 103 of the multiple scan lines 10 respectively. More specifically, the switch circuits 12 and the portion of the branch 103 located between the light-emitting diode and the first resistor are connected. The multiple switch circuits 12 of the same output line 11 are connected in parallel. Each branch 103 is provided with one switch circuit 12. The switch circuit 12 includes a push-button switch. Figure 1 The SW1 to SW9 marked in the diagram are push-button switches. The push-button switches correspond to the positions of the buttons (usually located below the buttons). When a button is pressed, the button will move down, triggering the push-button switch to close and making the switch circuit 12 conduct. Conversely, when the push-button switch is released, the button will reset and the push-button switch will open.

[0050] The first voltage terminal 100 of the scan line 10 is used to input a driving voltage signal. When a high-level driving voltage is applied to the first voltage terminal 100 of the scan line 100, the light-emitting diode (LED) is driven to emit light. The LED can illuminate the keys, thus serving as keyboard backlight. Optionally, the LED is arranged adjacent to and corresponding to the key switch, for example, it can be located below the key. In some embodiments, the key is at least partially transparent, for example, the part displaying the letters can be made transparent, so that the LED can illuminate the corresponding letters. In some embodiments, the key can be completely transparent to present a crystal-clear feel and improve aesthetics. In some embodiments, the key is opaque, and its inner wall is provided with a reflective surface (e.g., coated with a reflective coating) to reflect the light from the LED, so that the area below the key is illuminated, creating a sense of light around the key.

[0051] Understandably, when a push-button switch (e.g., SW1) is pressed, and a high-level driving voltage is applied to the first voltage terminal 100 of the scan line 10 (e.g., the first scan line 10a) connected to it, the voltage output terminal 110 of the output line 11 (e.g., the first output line 11a) connected to the push-button switch will detect a voltage signal, which will also be high-level. Obviously, due to the voltage division effect of the light-emitting diode and the first resistor, the voltage at the voltage output terminal 110 will be less than the voltage at the first voltage terminal 100. However, compared to the case where the push-button switch is open, it is still high-level, only smaller than the high level of the first voltage terminal 100. Therefore, when a voltage signal of a magnitude within a preset range is detected at the voltage output terminal 110 of the output line 11, it indicates that a push-button switch has been pressed.

[0052] In theory, as long as the button switch is not pressed, the voltage signal at the voltage output terminal 110 will always be 0. Therefore, in some embodiments, the preset range can be greater than 0V, that is, as long as a certain voltage is detected, it is considered that the button has been pressed.

[0053] In some embodiments, to reduce interference from the external environment and improve detection accuracy, the preset range can be a range greater than 0V. It is understood that the voltage at the voltage output terminal 110 after the button is pressed can be calculated using the forward voltage value of the LED, the input voltage at the first voltage terminal 110 of the scan line, and the line resistance, or it can be obtained through actual measurement. In practice, even if the detected voltage value is less than the calculated or measured voltage value, as long as it is within the allowable amplitude range, the button can be considered pressed to ensure the sensitivity of the detection result. This allowable amplitude range can be used as the preset range for judging the magnitude of the voltage signal. The voltage value obtained through calculation or measurement can be used as the basis for judging whether there is a voltage at the voltage output terminal 110 within the preset range. When the voltage output terminal 110 detects a voltage signal with a magnitude within the preset amplitude range, it indicates that a button has been pressed. Optionally, when a voltage signal with a magnitude greater than or equal to a fixed value is detected, it indicates that a button switch has been pressed. That is, the preset range is a voltage signal greater than or equal to a fixed value. This voltage signal can be less than a calculated or measured voltage value of a certain amplitude, or it can be equal to a calculated or measured voltage value.

[0054] During key detection, a high-level driving voltage is sequentially applied to the first voltage terminal 100 of each scan line 10. During the period when the high level is applied, the voltage output terminal 110 of each output line 11 is detected. When a voltage output terminal 110 detects a voltage within a preset amplitude range, it indicates that the key switch connected between the output line 11 and the scan line 10 with the high level applied has been pressed (i.e. triggered). Thus, the position information of the pressed key can be obtained, thereby realizing key detection.

[0055] For example, when a high level is applied to the first scan line 10a, if a certain voltage is detected at the voltage output terminal 110 of the first output line 11a, it indicates that the push button switch SW1 is pressed. If a certain voltage is detected at the voltage output terminal 110 of the second output line 11b, it indicates that the push button switch SW2 is pressed. If a certain voltage is detected at the voltage output terminals 110 of both the first output line 11a and the second output line 11b, it indicates that the push button switches SW1 and SW2 are pressed simultaneously. This process continues, and by combining the high-level scan line 10 with the voltage conditions at the voltage output terminals 110 of the multiple output lines 11, the pressed button position can be determined, thus achieving button detection.

[0056] Because a light-emitting diode (LED) is connected in series in scan line 10, the unidirectional conduction characteristic of the LED can be used to achieve the effect of preventing ghosting. For example, when current is applied to the second scan line 10b (i.e., a high-level driving voltage is applied), and button switches SW1, SW2, and SW4 are pressed simultaneously, only the voltage output terminal of the first output line 11a can detect a voltage within the preset amplitude range. Due to the unidirectional conduction of LED D1, the current cannot flow from the first output line 11a. Figure 2 The dashed line shown flows into the second output line 11b, causing the voltage output terminal 110 of the second output line 11b to detect a high level. It can be understood that when the LED is not set, current can flow along... Figure 2 The dashed line shown in the diagram allows both the first output line 11a and the second output line 11b to output a high level. At this time, it may cause the button switch SW5, which is not pressed, to be mistakenly judged as pressed. Therefore, the keyboard backlight circuit described above can play a role in preventing false detection.

[0057] Understandably, the circuit structure design described above achieves both the backlighting effect of the buttons and the anti-ghosting function, thus simplifying the circuit structure and reducing costs. Furthermore, the simplified circuit structure reduces the number of circuit board layers in the button output device, thereby helping to reduce the thickness of the button input device and achieve a thinner and lighter electronic device.

[0058] The keyboard backlight circuit includes a chip. The first voltage terminal 100 and the voltage output terminal 110 are both connected to the chip's IO interface. The chip can input drive voltage signals to multiple scan lines according to the control signal and detect the voltage signal of the voltage output terminal 110 of the output line 11, thereby realizing backlight and key detection.

[0059] Optionally, the second voltage terminal 101 is a ground voltage terminal.

[0060] In some embodiments, the resistance of the first resistor is 100–1000 ohms, and the driving voltage of the input first voltage terminal 100 is approximately 5V. Setting the resistance of the first resistor to 100–1000 ohms allows the current flowing through the LED to be 1–10mA, which meets the current requirements for most LEDs used in keyboards. In other embodiments, the driving voltage of the input first voltage terminal 100 is approximately 3.3V. In this case, the resistance of the first resistor can be selected as 30–500 ohms to ensure reliable LED illumination.

[0061] The resistance value of the first resistor can be adjusted according to the actual current and voltage parameters required for the LED to operate normally, so that the LED can emit light reliably.

[0062] In some embodiments, such as Figure 3 As shown, the switching circuit 12 also includes a second resistor connected in series with the push-button switch. Figure 3 R10 to R18, as indicated, are the second resistors. The resistance of the second resistor is greater than 0.2 times that of the first resistor; that is, the ratio of the resistance of the second resistor to the resistance of the first resistor is greater than 0.2. This ensures the reliability of the LED's illumination during button presses. It is understandable that... Figure 1 In the illustrated embodiment, when two or more push-button switches on the same output line 11 are pressed simultaneously, the first resistor corresponding to the pressed push-button switch will be connected in parallel. The resistance after parallel connection is smaller than the resistance of the individual first resistor, thus reducing the resistance used for voltage division with the LED and increasing the current and voltage acting on the LED. For example, refer to... Figure 1 When a high level is input to the first voltage terminal 100 of the first scan line 10a, and SW1 and SW4 are pressed simultaneously, the resistance of the two first resistors connected in parallel will be only half of the original value, even if the resistance values ​​of the first resistors R1 and R4 are the same. Therefore, the current flowing through the light-emitting diode will increase, and the voltage acting on the light-emitting diode will also increase. The more buttons are pressed at the same time, the smaller the resistance value of the resistor that divides the voltage with the light-emitting diode will be. In this way, the light-emitting diode may be burned out due to excessive current flowing through it, or the brightness may be too high, shortening its service life.

[0063] This problem can be solved by adding a second resistor in series with the push-button switch in the switching circuit 12.Figure 3 In the illustrated embodiment, when multiple buttons on the same output line 10 are pressed simultaneously, the presence of the second resistor results in a smaller decrease in the resistance of the resistor that ultimately divides the voltage with the LED. This ensures the stability of the current flowing through the LED when the button is pressed, reduces the current increase, and promotes reliable LED illumination, resulting in a more consistent and stable illumination effect. It also helps extend the LED's lifespan. For example, when the first voltage terminal 100 of the first scan line 10a is at a high level, and button switches SW1 and SW4 are pressed simultaneously, the first resistor R1 is connected in parallel with resistors R10, R13, and R4. Since the resistance values ​​of R10 and R13 are greater than 0.2 times the resistance values ​​of R1 and R4, the parallel resistance will be greater than the resistance value of R1 and R4 alone, reducing the current increase flowing through the LED.

[0064] To further ensure the stability of LED light emission, the resistance of the second resistor can be greater than or equal to 1, 2, 3, 4, 5, or more times the resistance of the first resistor. Optionally, the resistance of the second resistor is greater than or equal to twice the resistance of the first resistor, so that when the switch is pressed, the total current impact is less than 33%, the change in current flowing through the LED is smaller, and it will not cause significant optical and electrical effects on the LED, thereby effectively ensuring the stability of LED light emission and the reliability of its use.

[0065] Optionally, the resistance value of the second resistor should not exceed 10 times the resistance value of the first resistor. This is because the detection input of the output line is generally in a high-impedance state. When the resistance at the detection end is too large, it will affect the accuracy of the detection value. Setting the resistance value of the second resistor to be less than 10 times the resistance value of the first resistor is beneficial to improving the accuracy of the detection value.

[0066] Optionally, the first and second resistors can be ordinary resistors, carbon ink resistors, silver paste printed resistors, or other resistors that can be used in thin film circuits.

[0067] The color of light emitted by LEDs is not limited; for example, it can be white, red, blue, or green. Optionally, all LEDs can emit light of the same color, or at least two LEDs can emit light of different colors to produce a richer lighting effect. The color of LEDs in different positions can be set as needed.

[0068] The following section introduces a method for driving the backlight using the keyboard backlight circuit described above.

[0069] The keyboard backlight circuit driving method includes the following steps:

[0070] S1. A high level of a preset duration is sequentially applied to the first voltage terminal 100 of multiple scan lines 10, and at the same time, only the first voltage terminal 100 of one scan line 10 is applied with a high level, that is, at most one scan line 10 is applied with a high level at the same time.

[0071] S2. During the period when the high level is applied, detect the voltage signal at the voltage output terminal 110 of multiple output lines 11, and determine whether there is a voltage signal whose voltage magnitude is within the preset amplitude range, that is, determine whether the voltage magnitude of the detected voltage signal is within the preset amplitude range.

[0072] S3. When the magnitude of the voltage signal detected at a certain voltage output terminal 110 is within the preset amplitude range, the triggered button switch is determined by combining the voltage conditions of the high-level scan line 10 and the voltage output terminals 110 of multiple output lines 11.

[0073] It should be noted that in step S1, applying a high level for a preset duration to the first voltage terminal 100 of multiple scan lines 10 sequentially does not necessarily require applying the high level to the multiple scan lines 10 in the same order. For example, refer to... Figure 4 The total time from applying a high-level signal to the first scan line 10 to the last scan line 10 is one scan cycle T1. Therefore, it is sufficient to apply a high-level signal to all scan lines 10 within one scan cycle T1; they do not necessarily have to be in a specific order. For example, in the first scan cycle T1, the first scan line 10a, the second scan line 10b, and the third scan line 10c can be applied high-level signals sequentially. In the second scan cycle, the first scan line 10a, the third scan line 10c, and the second scan line 10b can be applied high-level signals sequentially. Of course, to simplify the program, it is optional to always apply high-level signals to the scan lines in the same order in each scan cycle T1, for example... Figure 4 In the process, a high level is sequentially applied to the first scan line 10a, the second scan line 10b, and the third scan line 10c.

[0074] In step S2, during the time period when each scan line 10 is connected to a high level, the voltage output terminal 110 of all output lines 11 is detected to ensure that no button is missed during detection.

[0075] Understandably, the scan period T1 is short enough that all scan lines 10 can be supplied with a high level at least once within the extremely short scan period, and the output voltage of all output lines 11 is detected when any scan line 10 is supplied with a high level, so that under normal operation, the button can be detected as pressed no matter when the hand presses the button.

[0076] Furthermore, to ensure continuous illumination of the LEDs, the scan period T1 is set to a time when flickering of the LEDs is imperceptible to the naked eye. Understandably, when a high level is input to a certain scan line 10, the LED on that scan line 10 will illuminate, while other LEDs will not. Therefore, the LEDs do not illuminate continuously but intermittently. When the interval is short enough, the flickering of the LEDs will be imperceptible to the naked eye, thus ensuring that the LEDs appear to be constantly lit.

[0077] Optionally, the interval between the light emission of the same LED is no more than 41.6ms, so that the human eye perceives it as constantly lit and cannot detect flickering.

[0078] Optionally, the scanning period T1 is no more than 41.6ms, which helps the LED to emit continuous light and ensures that the button is detected when the user presses it under normal operation.

[0079] To ensure sufficient time for detecting the voltage of the output line 11 after the scan line 10 is energized, in step S1, the duration of each high-level input on any scan line 10 is no less than 50 microseconds, allowing ample time for detecting the output line 11. Optionally, the duration of each high-level input on any scan line 10 is no less than 100 microseconds. As a further improvement, in step S2, the voltage output terminal 110 of the output line 11 is detected only after a preset time period following the high-level input on the scan line 10. Generally, the voltage level fluctuates (lasting approximately 10-30 microseconds) initially after the high-level input on the scan line 10. Therefore, performing voltage detection only after a preset time period following the high-level input on the scan line 10 allows for a more stable voltage at the output terminal 110, resulting in more accurate detection results. Optionally, the preset time period is greater than or equal to 30 microseconds, and more preferably greater than or equal to 50 microseconds, to ensure the accuracy of the detection results and avoid false detections caused by level fluctuations.

[0080] Optionally, step S3 includes the following steps:

[0081] S31. When the magnitude of the voltage signal at the voltage output terminal 110 of a certain output line 11 is detected to be within a preset amplitude range, a scan line 10 that is simultaneously supplied with a high level is acquired. For ease of description, the output line 11 corresponding to the voltage output terminal 110 whose detected voltage signal is within the preset amplitude range is referred to as the required output line 11.

[0082] S32. Identify the push-button switch connected between the detected qualified output line 11 and the scan line 10 that is simultaneously turned on with a high level, which is the push-button switch that has been triggered.

[0083] It is understandable that the position information of each button switch corresponding to the scan line 10 and the output line 11 has been recorded and stored in advance. Therefore, when the output line 11 with the detected voltage and the scan line 10 with the high level applied at the same time are known, the position information of the button switch can be obtained, thereby identifying which button switch is triggered. The position information of the button switch corresponds to the position of the button that was pressed.

[0084] Understandably, although the intermittent emission time of an LED is short enough and the frequency is fast enough to appear as continuous emission, the actual emission time of the LED is short over a period of time. For example, in the case of three scan lines 10, the LED emits light for only one-third of the time. This will result in the actual observed light brightness being lower than the light brightness observed when the LED is continuously powered on.

[0085] To address the aforementioned issue of low brightness, we will now introduce another keyboard backlight circuit driving method. For ease of description, the keyboard backlight circuit driving method described above will be referred to as the first keyboard backlight circuit driving method, and the one described below will be referred to as the second keyboard backlight circuit driving method.

[0086] refer to Figure 5 The second method for driving the keyboard backlight circuit includes the following steps:

[0087] A1. Drive the LED to emit light as needed during the first time period t10.

[0088] A2. During the second time period t11, key press detection is performed.

[0089] A3. Repeat steps A1 and A2 in sequence.

[0090] In the second keyboard backlight circuit driving method, all LEDs first emit light on demand during the first time period t10, such as remaining constantly lit, or creating breathing or flashing lighting effects. Then, during the second time period t11, key detection is performed, increasing the number of lighting modes. Simultaneously, while the LEDs continuously emit light during the first time period, within the same time frame (longer than the sum of the first and second time periods t10 and t11), the LED's on-time in the second method is longer than that in the first method. This results in higher perceived brightness, further improving display quality and aesthetics. When LEDs are used to illuminate letters on keys, they are more easily identified.

[0091] During the first time period t10, a driving voltage signal can be input to the first voltage terminal 100 of all scan lines 10 according to the control signal to drive all light-emitting diodes (LEDs) to emit light according to the control signal, such as continuously emitting light or producing a lighting effect. In some embodiments, a high level is continuously input to the first voltage terminal 100 of all scan lines 10 during the first time period t10. In this embodiment, the LEDs emit light continuously during the first time period t10 to maximize the brightness of light emitted by the naked eye. In other embodiments, a high level is input to the first voltage terminal 100 of all scan lines 10 according to the control signal during the first time period t10. The timing and sequence of inputting the high level can be set as needed, so that each LED emits light as needed, such as emitting light sequentially or at intervals, to produce diverse lighting effects. The LEDs can be controlled to emit light as needed, for example, by using PWM to control the LEDs to produce flashing or flowing light effects.

[0092] The first time period t10 and the second time period t11 constitute a light-emitting cycle. It can be understood that the longer the first time period t10, the longer the LED can continuously emit light during that period, resulting in a brighter perceived brightness. When the LED produces a lighting effect during this period, it reduces the visual perception of the light emitted during the second time period t11, better ensuring the continuity of the lighting effect. Optionally, the first time period t10 can be longer than the second time period t11, allowing the LED to emit light with good brightness and improving the continuity of the lighting effect. Further, the first time period t10 and the light-emitting cycle T2 should account for at least 80% of the total time. This ensures that the brightness perceived by the naked eye is approximately consistent with the brightness achieved by the LED when it is continuously powered, further improving the continuity of the lighting effect. The ratio of the first time period t10 to the light-emitting cycle T2 can be further selected to be at least 90%. Even further, the ratio of the first time period t10 to the light-emitting cycle T2 should not exceed 99.9% to prevent inaccurate button detection due to an excessively short detection time.

[0093] Understandably, the light emission period T2 needs to be short enough that all scan lines 10 can be switched on at least once within the extremely short light emission period T2, and the output voltage of all output lines 11 is detected when any scan line 10 is switched on, so that under normal operation, the button can be detected as pressed no matter when the hand presses the button.

[0094] Optionally, the duration of the light emission period T2 is no greater than (or less than or equal to, not exceeding) 41.6 ms, which helps the light-emitting diode to emit continuous light in a sensory sense, and ensures that under normal operation, the button can be detected as pressed regardless of when the hand presses the button.

[0095] Key detection can be achieved in various ways. This manual illustrates two methods. The first key detection step in step A2 includes:

[0096] A21. A high level of a preset duration is sequentially applied to the first voltage terminal 100 of multiple scan lines 10, and at the same time, only the first voltage terminal 100 of one scan line 10 is applied to the high level, that is, at most only one scan line 10 is applied to the high level at the same time.

[0097] A22. During the period when the high level is applied, detect the voltage signal at the voltage output terminal 110 of multiple output lines 11, and determine whether there is a voltage signal whose voltage magnitude is within the preset amplitude range.

[0098] A23. When the magnitude of the voltage signal detected at a certain voltage output terminal 110 is within the preset amplitude range, the triggered button switch is determined by combining the voltage conditions of the high-level scan line 10 and the voltage output terminals 110 of multiple output lines 11.

[0099] It is understandable that the key detection step in step A2 is basically the same as the step in the first keyboard backlight circuit driving method. You can refer to the relevant content in the first keyboard backlight circuit driving method above.

[0100] The total time from when a high-level signal is applied to the first scan line 10 to when a high-level signal is applied to the last scan line 10 is called one scan cycle T3. It is understood that in the second keyboard backlight circuit driving method, the second time period t11 and the scan cycle T3 have the same length. Of course, they can also be different, for example, refer to... Figure 6 A pause can be allowed before and / or after scan cycle T3 to ensure that the second time period t11 is longer than scan cycle T3. Furthermore, the second time period t11 is not limited to including only one scan cycle T3; it can include multiple scan cycles to perform more thorough detection and improve accuracy. Clearly, setting the second time period t11 and the time interval of N scan cycles T3 (N being an integer greater than or equal to 1) to the same length allows for more efficient use of time and improved work efficiency.

[0101] Similarly, the scan period T3 can be no more than 41.6 ms.

[0102] Similarly, in step A21, the duration of each high-level input on any of the scan lines 10 is no less than 50 microseconds, and more preferably no less than 100 microseconds. In step A22, the voltage output terminal 110 of the output line 11 is detected only after a preset time period following the high-level input to the scan line 10, to ensure a more stable voltage at the voltage output terminal 110 and more accurate detection results. Optionally, the length of the preset time period is greater than or equal to 30 microseconds, and more preferably greater than or equal to 50 microseconds, to ensure the accuracy of the detection results and avoid false detections caused by level jitter.

[0103] Similarly, step A23 may include the following steps:

[0104] A231. When the magnitude of the voltage signal at the voltage output terminal 110 of a certain output line 11 is within a preset amplitude range, the scan line 10 that is simultaneously supplied with a high level is acquired.

[0105] A232. Identify the push-button switch connected between the output line 11 of the detected composite requirement and the scan line 10 that is simultaneously supplied with a high level. This push-button switch is the triggered push-button switch. The output line 11 that meets the requirements refers to the output line 11 corresponding to the voltage output terminal 110 where the magnitude of the detected voltage signal is within the preset amplitude range.

[0106] Optionally, in order to make the human eye recognize the constantly lit light, the duration of the second time period t11 is less than or equal to 41.6ms, so that the human eye cannot recognize the flickering of the light-emitting diode during button detection.

[0107] Optionally, the duration of the light emission period T2 is not greater than (or less than or equal to, not exceeding) 41.6 ms, so that the duration of the light emission period T2 is short enough to reliably identify normal button operation by human hand. Optionally, the duration of the second time period t11 is less than or equal to 15 ms, so as to further improve the continuity of the light emission of the LED recognized by the human eye, and make the human eye observe the LED as basically always lit.

[0108] refer to Figure 7 The second button detection step in step A2 includes:

[0109] A21'. During the second time period t11, drive voltage signals are applied to the first voltage terminals 100 of all scan lines 10 in a preset manner. The frequency components of the drive voltage signals applied to different scan lines 10 are different, and the voltage signals of the voltage output terminals 110 of all output lines 11 are continuously received.

[0110] A22'. Sample the voltage signal received from the voltage output terminal 110 to obtain the frequency component information of the voltage signal from different voltage output terminals 110;

[0111] A23'. Determine the triggered push-button switch based on the frequency component information of the voltage signal.

[0112] The driving voltage signal can be, for example, a sine wave signal, a square wave signal, or other quadrature signals with a certain frequency. Since the voltage output terminal 110 of the output line 11 can only detect the voltage of the corresponding frequency component when the key switch on the output line 11 is pressed, the frequency component of the voltage signal at the voltage output terminal 110 can be used to determine which key is pressed. Furthermore, since the triggered key switch is determined by detecting the frequency component of the voltage signal, multiple (at least two or even all) scan lines 10 can be simultaneously supplied with driving voltage signals, without the need for sequential supply. When the same output line 11 detects voltage signals containing multiple different frequency components, it indicates that multiple key switches connected to different scan lines 10 have been pressed.

[0113] Specifically, step A23' may include the following steps:

[0114] A231'. Identify the scan line 10 of the driving voltage signal with the corresponding frequency component based on the frequency component information of the voltage signal at the voltage output terminal 110 of the output line 11;

[0115] A232'. Identify the push-button switch connected between the output line 11 and the scan line 10, which have the same voltage frequency components; this push-button switch is the one that has been triggered.

[0116] It is understandable that the position information of each button switch corresponding to the scan line 10 and the output line 11 has been recorded and stored in advance. Therefore, when the scan line 10 and the output line 11 with the same voltage frequency components are known, the position information of the button switch can be obtained, thereby identifying the triggered button switch. The position information of the button switch corresponds to the position of the button.

[0117] For example, refer to Figure 1 or Figure 3Drive voltage signals containing frequency components of 1kHz, 2kHz, and 3kHz are respectively applied to the first scan line 10a, the second scan line 10b, and the third scan line 10c. When the voltage output terminal 110 of the first output line 11a detects a voltage signal containing a 1kHz frequency component, the push-button switch SW1 connected to the first output line 11a and the first scan line 10a can be located (indicating that the push-button switch SW1 is pressed), and the position information corresponding to the push-button switch can be obtained to determine the pressed button. When the voltage output terminal 110 of the first output line 11a detects voltage signals containing frequency components of 1kHz, 2kHz, and 3kHz, the push-button switches connected between the first output line 11a and the first scan line 10a, the second scan line 10b, and the third scan line 10c can be identified as SW1, SW4, and SW7, indicating that the push-button switches SW1, SW4, and SW7 are all pressed. The position information corresponding to the push-button switches SW1, SW4, and SW7 can be obtained to determine the pressed button. The button conditions for other output lines 11 can be deduced similarly. For example, when drive voltage signals containing 1KHz, 2KHz, and 3KHz frequency components are applied to the first scan line 10a, the second scan line 10b, and the third scan line 10c, respectively, if the voltage output terminal 110 of the first output line 11a detects a voltage signal containing a 1KHz frequency component, it indicates that the button switch SW1 is pressed. If the voltage output terminal 110 of the first output line 11a detects voltage signals containing 1KHz, 2KHz, and 3KHz frequency components, it indicates that the button switches SW1, SW4, and SW7 are all pressed. The button conditions for other output lines 11 can be deduced similarly.

[0118] Optionally, in step A21', the difference in the center frequency of the driving voltage signal supplied to the first voltage terminal 100 of each scan line 10 is not less than one percent of the highest sampling rate of the output line, so that the frequency components of the voltage signal have a large difference, which facilitates accurate identification of the frequency component information of the voltage output terminal 110.

[0119] Optionally, in step A22', the frequency component information of the voltage signal at different voltage output terminals 110 is obtained by performing Fourier expansion on the sampled voltage signal.

[0120] Understandably, since multiple scan lines 10 can be driven with voltage signals simultaneously and the output line 11 can be continuously sampled and detected, there is no need to sequentially apply driving voltage signals to the scan lines 10. Therefore, compared to sequentially applying high-level signals to the scan lines 10 for detection, the time for applying driving voltage signals to each scan line 10 can be increased, thus effectively ensuring the detection time and improving detection accuracy. Furthermore, the frequency of the voltage is less susceptible to external environmental influences (such as static electricity) than the voltage magnitude, further enhancing detection accuracy.

[0121] It is understandable that applying a driving voltage signal to the first voltage terminal 100 of the scan line 10 in a preset manner can include various methods.

[0122] In some embodiments, the preset method is to continuously supply a driving voltage signal to the first voltage terminal 100 of all scan lines 10. In this embodiment, since the driving voltage signal can be continuously supplied and the output line 11 is continuously detected, the accuracy of key detection can be greatly improved, timeliness can be guaranteed, delay can be reduced, and the situation where no key operation is detected due to the time interval of the driving voltage signal supply will not occur, making it more reliable. Furthermore, each scan line 10 has a continuous voltage input during key detection, so each light-emitting diode can still emit light continuously during the second time period t11. When the continuous emission of light-emitting diodes is required, the continuity and brightness of the observed light can be increased.

[0123] In other embodiments, the preset method is to apply a high-level driving voltage to the scan line 10 according to a preset power-on cycle for each scan line. The power-on cycle of each scan line 10 may be the same or different. The power-on cycle includes power-on time and non-power-on time. It is understood that the voltage signal applied within the power-on cycle is a driving voltage signal with a certain frequency component. The power-on time included in the power-on cycle corresponding to each scan line 10 may be the same or different. (Refer to...) Figure 8 and Figure 9 The energizing periods of the first scan line 10a, the second scan line 10b, and the third scan line 10c are T3, T4, and T5, respectively. Figure 8 In the illustrated embodiment, the durations of the power-on cycles T3, T4, and T5 are different, and the power-on time t_on and the non-power-on time t_off each account for half of the power-on time within the power-on cycle of each scan line 10. Figure 9 In the illustrated embodiment, the durations of the power-on cycles T3, T4, and T5 are the same, and the power-on time ton within each power-on cycle of each scan line 10 is much longer than the non-power-on time toff. This allows for a longer power-on time for the scan lines 10, which is more conducive to improving the accuracy of button detection and reducing the delay in button detection. Further optionally, when a driving voltage is applied to the scan line 10 according to a preset power-on cycle for each scan line, all scan lines 10 or at least two scan lines 10 are simultaneously supplied with driving voltage signals within a certain time period.

[0124] Optionally, within one power-on cycle, the power-on time is greater than 1 / M of the power-on cycle, where M is the total number of scan lines 10 in the keyboard backlight circuit. This can improve the power-on time, ensuring detection accuracy, and also increase the light-emitting time of the LEDs, increasing the perceived brightness. Further, optionally, within one power-on cycle, the power-on time is greater than half of the power-on cycle to further improve the effect.

[0125] Understandably, keyboards use backlighting units to illuminate the keys. These units are located below the keys and emit light towards the side where the key is located. Typically, each key has its own backlighting unit. The backlight color can be monochrome or multi-colored. When the backlight color is monochrome, it can be white, red, green, blue, or other colors. In this case, the backlighting unit may consist of only one LED, which is connected in series... Figure 1 and Figure 3 The circuit shown enables light emission. When the backlight color is colored, richer color effects can be achieved. For example, the color can gradually change, making the backlight effect more dazzling. In this case, the light-emitting unit can include at least two light-emitting diodes that emit light of different colors. The light-emitting diodes of different colors can emit a single color or mix to emit a new color, thus making the colors richer.

[0126] The present invention also proposes a key input device, which includes any of the keyboard backlight circuits described above. The key input device may be a keyboard, such as the keyboard of a mobile phone or computer.

[0127] Keypad input devices include keypad circuit boards, such as Figure 10 As shown, the button circuit board includes a first circuit board 40 and a second circuit board 41 arranged at an interval between the upper and lower parts, and a spacer layer 42 connecting the first circuit board 40 and the second circuit board 41. The first circuit board 40 is located above the second circuit board 41 and is provided with an output line 11 and a second resistor (if present). The second circuit board 41 is provided with a scan line 10, a light-emitting diode 46 and a first resistor (not shown in the figure). Conductive lines (e.g., silver paste lines) can be provided on the first circuit board 40 and the second circuit board 41 to form the scan line 10 and the output line 11.

[0128] The push-button switch is connected between the first circuit board 40 and the second circuit board 41, such as... Figure 10As shown, the push-button switch includes a first contact 430 located on the first circuit board 40 and electrically connected to the output line 11, and a second contact 431 located on the second circuit board 41 and electrically connected to the scan line 10. The two contacts are arranged at intervals relative to each other, and the spacer layer 42 is provided with a cavity 420 for exposing the first contact 430 and the second contact 431. A reset member 44 and a button 45 are correspondingly arranged above the push-button switch. The reset member 44 can be made of elastic materials such as rubber or silicone. When the button 45 is pressed, the button 45 presses down the reset member 44 and the push-button switch, so that the first contact 430 and the second contact 431 are in contact, and the scan line 10 and the output line 11 are connected. When the button 45 is released, the button 45 is reset by the elastic force of the reset member 44, and the scan line 10 and the output line 11 are disconnected.

[0129] An LED 46 is disposed on a second circuit board 41. A clearance hole 400 is formed on the spacer layer 42 and the first circuit board 40 to expose the LED 46. The LED 46 is disposed within the clearance hole 400, and its light can be emitted towards the button 45. In some embodiments, the button 45 is provided with a light-transmitting area 450 made of transparent material. The light-transmitting area 450 can, for example, be consistent with the letters / graphics marked on the button 45, so that the light from the LED 46 can illuminate the letters / graphics, making it more aesthetically pleasing. The button 45 can also be made completely transparent, in which case the portion of the button 45 other than the portion marked with letters / graphics forms the light-transmitting area 450 (i.e., the light-transmitting area 450 includes cases where the button 45 is partially transparent or completely transparent). In other embodiments, refer to... Figure 11 A reflective layer 451 is provided on the inner surface of the button 45. The reflective layer 451 has a reflective surface that reflects the light of the light-emitting diode 46. The reflected light illuminates the area around the button 45, improving its aesthetics. In other embodiments, if the inner surface of the button 45 itself has a good reflective effect, the reflective layer 451 may not be provided, and the inner surface of the button 45 may be used directly as the reflective surface.

[0130] It is understandable that when the light-emitting unit includes multiple light-emitting diodes, the other diodes and the corresponding control circuits and the third resistor can be set on the second circuit board 41, or they can be set on the first circuit board 40.

[0131] Optionally, both the first circuit board 40 and the second circuit board 41 are thin-film circuits.

[0132] In this invention, only two circuit boards are needed to achieve the functions of anti-ghosting key detection and backlight display, which simplifies the structure of the circuit board, makes the circuit design of the key input device simpler, and the overall thickness of the circuit board can be reduced. In this way, the key input device can also be made smaller, which can effectively reduce the thickness of laptops and other products with high requirements for thinness and lightness, and improve product competitiveness.

[0133] The present invention also proposes an electronic device comprising any of the keyboard backlight circuits described above or any of the key input devices described above. The electronic device may be, for example, a mobile phone with keys, a laptop computer, a desktop computer, a game console, or other devices with keys.

[0134] This invention also proposes a processor-readable storage medium for storing processor-executable instructions. When these instructions are loaded and executed by the processor, they can implement any of the keyboard backlight circuit driving methods described above. It is understood that key input devices and / or electronic devices may include this processor-readable storage medium.

[0135] It should be noted that, in the absence of conflict, the various embodiments described herein can be combined with each other to obtain more implementation schemes.

[0136] The above are merely specific embodiments of the present invention, and any improvements made based on the concept of the present invention shall be considered within the scope of protection of the present invention.

Claims

1. A method for driving a keyboard backlight circuit, characterized in that, The keyboard backlight circuit driving method is executed by a keyboard backlight circuit integrated with a key detection function, the keyboard backlight circuit integrated with the key detection function comprises a plurality of scanning lines (10) arranged at intervals and a plurality of output lines (11) arranged at intervals, the plurality of output lines (11) and the plurality of scanning lines (10) are staggered to form a matrix circuit, the scanning lines (10) are used to input a driving voltage signal, the scanning lines (10) are provided with light-emitting diodes for keyboard backlight, the output lines (11) have a plurality of switch circuits (12) connected to the plurality of scanning lines (10) respectively, the switch circuit (12) comprises a key switch, the scanning lines (10) have a main line (102) and a plurality of parallel branch lines (103) connected to the main line (102), the main line (102) has a first voltage end (100), the branch line (103) has a second voltage end (101), the second voltage end (101) is a ground voltage end, the branch line (103) and the main line (102) are sequentially provided with the light-emitting diode and the first resistor in series between the connection position of the main line (102) and the second voltage end (101), the light-emitting diode allows unidirectional conduction of current to the first resistor; the plurality of output lines (11) correspond to the plurality of branch lines (103) of the scanning lines (10) one by one, the output lines (11) have a voltage output end (110) and a plurality of switch circuits (12) connected to the branch lines (103) of the plurality of scanning lines (10) respectively, each branch line (103) is provided with one switch circuit (12), and the switch circuit (12) is connected to the part of the branch line (103) between the light-emitting diode and the first resistor; The keyboard backlight circuit driving method comprises the following steps: A1. driving the light-emitting diodes to emit light as needed in a first time period t10, so that all the light-emitting diodes are always on or form a light effect; A2. performing key detection on all key switches in a second time period t11; A3. repeating steps A1 and A2 in turn.

2. The keyboard backlight circuit driving method of claim 1, wherein, The first time period t10 and the second time period t11 form a light-emitting period T2, and the first time period t10 is greater than or equal to the second time period t11.

3. The method of claim 2, wherein the key backlight circuit is driven by a key backlight circuit driver. The time ratio of the first time period t10 to the light-emitting period T2 is not less than 80%, and the time ratio of the first time period t10 to the light-emitting period T2 is not more than 99.9%.

4. The method of claim 1, wherein the key backlight circuit is driven by a key backlight circuit driver. In step A1, a driving voltage signal is input to the first voltage end (100) of all the scanning lines (10) according to a control signal in the first time period, so as to drive all the light-emitting diodes to continuously emit light or produce a light effect.

5. The method of claim 1, wherein the method further comprises: determining whether the key is pressed; and if the key is pressed, turning on the light source. The length of the second time period t11 is less than or equal to 41.6 ms.

6. The keyboard backlight circuit driving method of claim 5, wherein, The first time period t10 and the second time period t11 form a light-emitting period T2, the length of the light-emitting period T2 is less than or equal to 41.6 ms, and the length of the second time period t11 is less than or equal to 15 ms.

7. The method of claim 1, wherein the method further comprises: determining whether the key is pressed; and if the key is pressed, turning on the light source. The step A2, the key detection includes: A21. sequentially inputting high level to the first voltage end (100) of the plurality of scan lines (10) for a preset time duration, and only inputting high level to the first voltage end (100) of one of the scan lines (10) at the same time; A22. detecting the voltage signal of the voltage output end (110) of the plurality of output lines (11) in the time duration of inputting high level, and judging whether the voltage size is within the preset amplitude value range; A23. when detecting that the size of the voltage signal of a certain voltage output end (110) is within the preset amplitude value range, judging the triggered key switch in combination with the voltage of the scan line (10) inputting high level and the voltage output end (110) of the plurality of output lines (11).

8. The method of claim 7, wherein the key backlight circuit is driven by a key backlight circuit driver. The step A23 includes the following steps: A231. when detecting that the size of the voltage signal of a certain voltage output end (110) is within the preset amplitude value range, obtaining the scan line (10) inputting high level at the same time; A232. identifying the key switch connected between the output line (11) meeting the requirement and the scan line (10) inputting high level at the same time, and the key switch is the triggered key switch, and the output line (11) meeting the requirement refers to the output line (11) corresponding to the voltage output end (110) whose detected voltage signal size is within the preset amplitude value range.

9. The method of claim 1, wherein the method further comprises: determining whether the key is pressed; and if the key is pressed, turning on the light source. The switch circuit (12) further includes a second resistor connected in series with the key switch.

10. The method of claim 9, wherein the key backlight circuit is driven by a key backlight circuit driver. The resistance value of the second resistor is less than or equal to 10 times the resistance value of the first resistor, and greater than or equal to 0.2 times the resistance value of the first resistor.

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