Keyboard backlight circuit and key input device

Abstract

The utility model discloses a keyboard backlight circuit integrated with a key detection function and a key input device, the keyboard backlight circuit comprises a plurality of scanning lines and a plurality of output lines, each scanning line is provided with a main line and a plurality of parallel branch lines connected with the main line, the main line is provided with a first voltage end, the branch lines are provided with second voltage ends, and the second voltage ends are connected with the main line. A light-emitting diode and a first resistor which are connected in series are sequentially arranged between the connection position of the branch line and the main line and the second voltage end, and the light-emitting diode enables current to be conducted towards the first resistor in a one-way mode; the output line is provided with a voltage output end and a plurality of switching circuits connected with the scanning lines respectively, the switching circuits are connected with the portions, located between the light-emitting diodes and the first resistors, of the scanning lines, and the switching circuits comprise key switches. The switch circuit is connected in series in the keyboard backlight circuit, so that the keyboard backlight effect is achieved, and the functions of key detection and ghost key prevention can be achieved at the same time.

Description

Technical Field

[0001] The utility model relates to an information input device, in particular to a keyboard backlight circuit and a key input device with an integrated key detection function. Background Art

[0002] With the development of technology, electronic devices have become more and more diverse. In order to achieve human-computer interaction, electronic devices are usually equipped with buttons. For example, computers are often equipped with keyboards for typing, gaming, and other operations.

[0003] To make keyboards easier to use in dark or dim environments, some keyboards have a backlight function. This function uses LEDs (light-emitting diodes) to illuminate the keys or the area around the keys, allowing users to identify the location of each key and accurately operate the keys. The keyboard backlight function is achieved through the keyboard's backlight circuit. The backlight circuit has LEDs corresponding to the key positions, and the backlight function is achieved by controlling the LEDs to emit light.

[0004] Furthermore, in order to receive key information, the keyboard is also provided with a key detection circuit, which identifies which key is pressed through the key detection circuit.

[0005] That is to say, for a keyboard with a backlight function, a keyboard backlight circuit and a key detection circuit need to be set up inside it at the same time, resulting in a complex circuit layout, a large number of circuit board layers or the need for multiple circuit boards to be stacked, and a large thickness, which ultimately leads to a thicker keyboard and higher cost.

[0006] For some products that pursue thinness and lightness, complex circuit board design will make the circuit board as a whole too thick, which cannot meet the requirements of thinness and lightness of laptops.

[0007] The above content is only used to help understand the technical solution of this application and does not constitute an admission that the above is prior art. Utility Model Content

[0008] The purpose of the utility model is to provide a keyboard backlight circuit and a key input device with integrated key detection function, which can realize the keyboard backlight function and the anti-ghosting key detection function and has a simple circuit structure.

[0009] To achieve the above-mentioned purpose of the utility model, in a first aspect, the utility model proposes a keyboard backlight circuit with integrated key detection function, comprising:

[0010] a plurality of scan lines, the plurality of scan lines being arranged at intervals, the scan lines comprising a main line and a plurality of parallel branch lines connected to the main line, the main line having a first voltage terminal, the branch lines having a second voltage terminal, a light-emitting diode and a first resistor being sequentially arranged in series between a connection position between the branch lines and the main line and the second voltage terminal, the light-emitting diode being used to realize keyboard backlighting and causing current to flow unidirectionally toward the first resistor; and,

[0011] A plurality of output lines are arranged at intervals and staggered with the scan lines to form a matrix circuit. The output lines have voltage output terminals and a plurality of switch circuits respectively connected to the branches of the plurality of scan lines. Each branch line is provided with a corresponding switch circuit. The switch circuit is connected to a portion of the branch line located between the light-emitting diode and the first resistor. The switch circuit includes a key switch.

[0012] Furthermore, the first voltage terminal and the voltage output terminal are both connected to the IO interface of the chip, the chip inputs a driving voltage signal to the plurality of scanning lines, and detects the voltage signal at the voltage output terminal of the output line; the second voltage terminal is a ground voltage terminal.

[0013] Furthermore, the driving voltage applied to the first voltage terminal is 5V, and the resistance of the first resistor is 100 to 1000 ohms; or,

[0014] The driving voltage supplied to the first voltage terminal is 3.3V, and the resistance of the first resistor is 30 to 500 ohms.

[0015] Furthermore, the colors of the light emitted by all the light emitting diodes are the same; or, the colors of the light emitted by at least two light emitting diodes are different.

[0016] Furthermore, the switch circuit further includes a second resistor connected in series with the key switch.

[0017] Furthermore, the resistance of the second resistor is greater than 0.2 times the resistance of the first resistor.

[0018] Furthermore, the resistance of the second resistor is greater than or equal to 2 times the resistance of the first resistor and less than or equal to 10 times the resistance of the first resistor.

[0019] In a second aspect, the present invention provides a key input device, comprising the keyboard backlight circuit with integrated key detection function as described above.

[0020] Furthermore, the key input device includes:

[0021] A first circuit board is provided with the output line;

[0022] A second circuit board is provided with the scan line, the light emitting diode and the first resistor; and

[0023] a key switch, comprising a first contact located on the first circuit board and electrically connected to the output line, and a second contact located on the second circuit board and electrically connected to the scan line, wherein the first contact and the second contact are spaced apart from each other;

[0024] A reset member and a button are correspondingly arranged above the button switch. The light-emitting diode is arranged below the button and exposed on the first circuit board to emit light toward the button. The first circuit board is closer to the button than the second circuit board.

[0025] Furthermore, the key input device further includes a spacer layer connected between the first circuit board and the second circuit board, the spacer layer and the first circuit board are provided with avoidance holes, and the light-emitting diode is located in the avoidance hole.

[0026] Furthermore, the button is provided with a light-transmitting area for allowing the light of the light-emitting diode to pass through; or,

[0027] The inner wall of the button is provided with a reflective surface.

[0028] Compared to the prior art, the present invention has the following advantages: According to some embodiments of the present invention, a keyboard backlight circuit with integrated key detection function integrates a switch circuit in series with the keyboard backlight circuit, thereby providing a keyboard backlight effect while also realizing key detection and anti-ghosting functions. This simplifies the circuit structure and helps reduce costs. Furthermore, the simplified circuit structure can reduce the number of layers in the circuit board of the key output device, thereby reducing the thickness of the key input device and achieving a lighter and thinner electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a circuit diagram of a keyboard backlight circuit with an integrated key detection function according to an embodiment of the present invention.

[0030] Figure 2 yes Figure 1 The circuit shown is a schematic diagram for preventing false detection.

[0031] Figure 3 This is a circuit diagram of a keyboard backlight circuit with an integrated key detection function in an embodiment of the present invention. In the diagram, a second resistor is provided in the switch circuit.

[0032] Figure 4 This is a timing diagram of applying a high level to each scanning line during key detection in an embodiment of the present invention, and shows two scanning cycles.

[0033] Figure 5 It is a structural diagram of a key input device in one embodiment of the present utility model.

[0034] Figure 6 It is a structural diagram of a key input device in one embodiment of the present utility model. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0037] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] The present invention proposes a keyboard backlight circuit with an integrated key detection function (hereinafter referred to as the keyboard backlight circuit), which can be used in a keyboard or an electronic device with multiple keys. The keyboard backlight circuit can realize the backlight of the keyboard and can also detect the keys to determine which key of the device is pressed.

[0039] like Figure 1 As shown, the keyboard backlight circuit corresponding to an 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. The scan lines 10 and the output lines 11 are staggered to form a matrix circuit. Figure 1 As shown, Figure 1The number of scan lines 10 and output lines 11 shown is 3. For the convenience of description, the three scan lines 10 from top to bottom are respectively referred to as the first scan line 10a, the second scan line 10b and the third scan line 10c, and the three output lines 11 from left to right are respectively referred to as the first output line 11a, the second output line 11b and the third output line 11c.

[0040] It should be noted that, herein, "plurality" or "multiple" or similar expressions indicate that the number is at least two, i.e., "plurality" means two or more. Therefore, in other embodiments, the number of scan lines 10 and output lines 11 may be two or more than three. It should be further noted that, although the number of scan lines 10 and output lines 11 is the same in the illustrated embodiment, this is not necessarily the case. The number of the two can be different, for example, one can be two and the other can be three, etc.

[0041] The scanning line 10 has a first voltage terminal 100 and a second voltage terminal 101. The number of the 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 a plurality of branch lines 103 connected to the main line 102. The plurality of 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 1 D1 to D9 are light-emitting diodes, and R1 to R9 are first resistors. The light-emitting diodes conduct current unidirectionally toward the second voltage terminal 101. That is, the current input from the first voltage terminal 100 flows into the anode of the light-emitting diode, then flows out from the cathode of the light-emitting diode and flows through the first resistor, causing the light-emitting diode to emit light. It is understood that due to the unidirectional conduction characteristic of the light-emitting diode, current cannot flow from the cathode to the anode.

[0042] The output line 11 has a voltage output terminal 110 and multiple switch circuits 12 respectively connected to the multiple scan lines 10. Specifically, the multiple switch circuits 12 are respectively connected to the branches 103 of the multiple scan lines 10. More specifically, the switch circuits 12 are connected to the portion of the branch 103 located between the light-emitting diode and the first resistor. The multiple switch circuits 12 of the same output line 11 are connected in parallel. Each branch 103 is provided with a corresponding switch circuit 12. The switch circuit 12 includes a key switch, Figure 1 SW1 to SW9 are key switches, which correspond to the position of the key (usually located below the key). When the key is pressed, the key moves downward, thereby triggering the key switch to close and turn on the switch circuit 12. Conversely, when the key switch is released, the key is reset and the key switch is turned off.

[0043] The first voltage terminal 100 of the scanning line 10 is used to pass a driving voltage signal. When a high-level driving voltage is applied to the first voltage terminal 100 of the scanning line 100, the light-emitting diode is driven to emit light. The light-emitting diode can illuminate the key, thereby acting as a keyboard backlight. Optionally, the light-emitting diode is arranged adjacent to the key switch and corresponding to the key, for example, it can be located below the key. In some embodiments, the key is at least partially transparent, for example, the part that displays the letters can be set to transparent, so that the light-emitting diode can illuminate the corresponding letter. In some embodiments, the key can be fully transparent to present a crystal clear feeling and improve the aesthetics. In some embodiments, the key is opaque, and its inner wall is provided with a reflective surface (for example, coated with a reflective coating), which can reflect the light of the light-emitting diode, so that the bottom of the key is illuminated, creating a sense of light around the key.

[0044] It can be understood that when the key switch (for example, SW1) is pressed and a high-level driving voltage is applied to the first voltage terminal 100 of the scan line 10 (for example, the first scan line 10a) connected thereto, the voltage output terminal 110 of the output line 11 (for example, the first output line 11a) connected to the key switch will detect a voltage signal, which is also reflected as a high level. Obviously, due to the voltage dividing effect of the light-emitting diode and the first resistor, etc., the voltage at the voltage output terminal 110 will be lower than the voltage at the first voltage terminal 100, but compared to the case where the key switch is disconnected, it is still reflected as a high level, but it is smaller than the high level of the first voltage terminal 100. Therefore, when a voltage signal whose size is within a preset range is detected at the voltage output terminal 110 of the output line 11, it indicates that a key switch is pressed.

[0045] Theoretically, as long as the key switch is not pressed, the voltage signal at the voltage output terminal 110 is always 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 key is pressed.

[0046] In some embodiments, in order to reduce interference caused by the external environment and improve the accuracy of detection, the preset range can be a range greater than 0V. It is understandable that the voltage magnitude of the voltage output terminal 110 after pressing the key can be obtained by calculating the forward voltage value of the light-emitting diode, the input voltage of the first voltage terminal 110 of the scanning line and the line resistance, or it can be obtained by actual measurement. In actual implementation, even if the detected voltage value is less than the calculated voltage value or the measured voltage value, as long as it is within the allowable amplitude range, it can be considered that the key is pressed to ensure the sensitivity of the detection result. The allowable amplitude range can be used as a preset range for judging the voltage signal magnitude. The voltage value obtained by calculation or actual measurement can be used as a basis for judging whether the voltage output terminal 110 has a voltage within the preset range. When the voltage output terminal 110 detects a voltage signal whose voltage magnitude is within the preset amplitude value range, it indicates that a key is pressed. Optionally, when a voltage signal with a voltage greater than or equal to a fixed value is detected, it indicates that a key switch is pressed, that is, the preset range is a voltage signal greater than or equal to a fixed value. The voltage signal can be less than a certain amplitude of the calculated or measured voltage value, or it can be equal to the calculated or measured voltage value.

[0047] When performing key detection, a high-level driving voltage is applied to the first voltage terminal 100 of each scanning line 10 in turn, and the voltage output terminal 110 of each output line 11 is detected during the period of applying the high level. When a voltage output terminal 110 detects a voltage within a preset amplitude value range, it indicates that the key switch connected between the output line 11 and the scanning line 10 applied with the high level is pressed (i.e., triggered), so that the position information of the pressed key can be obtained, thereby realizing key detection.

[0048] 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 key 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 key 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 key switches SW1 and SW2 are pressed simultaneously. Similarly, by combining the voltages of the voltage output terminals 110 of the scan line 10 supplied with a high level and the multiple output lines 11, the location of the pressed key can be determined, thus achieving key detection.

[0049] Since the light-emitting diodes are connected in series in the scanning line 10, the unidirectional conduction characteristics of the light-emitting diodes can be used to achieve the anti-ghosting effect. For example, when the second scanning line 10b is supplied with current (i.e., a high-level driving voltage is supplied), and the key switches SW1, SW2, and SW4 are pressed at the same time, only the voltage output end of the first output line 11a can detect a voltage within the preset amplitude value range. Due to the unidirectional conduction effect of the light-emitting diode D1, the current cannot flow out of the first output line 11a. Figure 2 The dotted line shown flows into the second output line 11b, so that the voltage output terminal 110 of the second output line 11b detects a high level. It can be understood that when the light emitting diode is not provided, the current can flow along Figure 2 The dotted line shown flows, so that the first output line 11a and the second output line 11b both output a high level. At this time, the key switch SW5 that is not pressed may be mistakenly judged as pressed. Therefore, the above-mentioned keyboard backlight circuit can prevent false detection.

[0050] It is understood that the above circuit structure design not only achieves the key luminous effect but also provides an anti-ghosting function, thereby simplifying the circuit structure and helping to reduce costs. Furthermore, the simplified circuit structure can reduce the number of layers in the circuit board of the key output device, thereby reducing the thickness of the key input device and achieving a lighter and thinner electronic device.

[0051] The keyboard backlight circuit includes a chip, and the first voltage terminal 100 and the voltage output terminal 110 are both connected to the IO interface of the chip. The chip can input a driving voltage signal to multiple scanning 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.

[0052] Optionally, the second voltage terminal 101 is a ground voltage terminal.

[0053] In some embodiments, the resistance of the first resistor is 100-1000 ohms, and the driving voltage input to the first voltage terminal 100 is approximately 5V. Setting the resistance of the first resistor to 100-1000 ohms can result in a current of 1-10mA flowing through the LED, which meets the current requirements of most LEDs used in keyboards. In other embodiments, the driving voltage input to the first voltage terminal 100 is approximately 3.3V. In this case, the resistance of the first resistor can be selected to be 30-500 ohms to ensure reliable LED illumination.

[0054] The resistance value of the first resistor can be adjusted according to the current and voltage parameters actually required for the normal operation of the light emitting diode, so that the light emitting diode can emit light reliably.

[0055] In some embodiments, as Figure 3As shown, the switch circuit 12 further includes a second resistor connected in series with the key switch. Figure 3 The R10 to R18 indicated in the figure are the second resistors, the resistance of which is greater than 0.2 times 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, so as to ensure the reliability of the light emitting diode during the key pressing process. Figure 1 In the embodiment shown, when two or more key switches on the same output line 11 are pressed simultaneously, the first resistors corresponding to the pressed key switches will be connected in parallel. The resistance of the parallel connection is smaller than the resistance of the first resistor alone, so that the resistance for voltage division with the light-emitting diode becomes smaller, and the current and voltage acting on the light-emitting diode will become larger. For example, referring to Figure 1 When a high level is input to the first voltage terminal 100 of the first scan line 10a, SW1 and SW4 are pressed simultaneously. When the resistance values of the first resistors R1 and R4 are the same, the resistance of the two first resistors connected in parallel will be only half of the original value. 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 key switches are pressed at the same time, the smaller the resistance value of the voltage divided by the light-emitting diode will be. In this way, the light-emitting diode may be burned out due to excessive current flowing through the light-emitting diode, or the brightness may be too high, shortening its service life.

[0056] This problem can be solved by providing a second resistor in series with the key switch in the switch circuit 12. Figure 3 In the illustrated embodiment, when multiple keys on the same output line 10 are pressed simultaneously, the presence of the second resistor causes the resistance of the resistor ultimately dividing the voltage with the light-emitting diode to decrease relatively less, thereby ensuring the stability of the current flowing through the light-emitting diode when the key is pressed and reducing the current increase. This facilitates reliable light emission from the light-emitting diode, resulting in a more consistent and stable light emission effect, and also helps extend its service life. For example, when a high level is input to the first voltage terminal 100 of the first scan line 10a and the key switches SW1 and SW4 are pressed simultaneously, the first resistor R1 is connected in parallel with the resistors R10, R13, and R4. Since the resistance of the resistors R10 and R13 is greater than 0.2 times the resistance of the resistors R1 and R4, the parallel resistance is greater than the resistance of only R1 and R4 in parallel, reducing the increase in the current flowing through the light-emitting diode.

[0057] To further ensure the stability of the light emitting diode's 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 2 times the resistance of the first resistor, so that after pressing the switch, the total current impact is less than 33%, the change in the current flowing through the light emitting diode is smaller, and there is no significant optical or electrical impact on the light emitting diode, thereby effectively ensuring the stability of the light emitting diode's emission and the reliability of its use.

[0058] Optionally, the resistance of the second resistor does not exceed 10 times the resistance of the first resistor. Because the detection input of the output line is generally in a high-resistance state, when the resistance of the detection end is too large, it will affect the accuracy of the detection value. Setting the resistance of the second resistor to be less than 10 times the resistance of the first resistor is conducive to improving the accuracy of the detection value.

[0059] Optionally, the first resistor and the second resistor may be ordinary resistors, carbon ink resistors, silver paste printed resistors, or other resistors that can be used for thin film circuits.

[0060] The color of the light emitted by the LEDs is not limited and can be, for example, white, red, blue, or green. Optionally, all LEDs can emit the same color, or at least two LEDs can emit light of different colors to produce a richer lighting effect. The colors of the LEDs in different positions can be set as needed.

[0061] Next, a method for driving the backlight using the keyboard backlight circuit described above will be described.

[0062] The keyboard backlight circuit driving method includes the following steps:

[0063] S1. A high level of a preset duration is applied to the first voltage terminals 100 of multiple scan lines 10 in sequence, and a high level is applied to the first voltage terminal 100 of only one scan line 10 at a time, that is, a high level is applied to at most one scan line 10 at a time.

[0064] S2. Detect the voltage signals of the voltage output terminals 110 of the plurality of output lines 11 during the period of high level, and determine whether there is a voltage signal whose voltage magnitude is within a preset amplitude value range, that is, determine whether the voltage magnitude of the detected voltage signal is within the preset amplitude value range.

[0065] S3. When it is detected that the voltage signal of a certain voltage output terminal 110 is within the preset amplitude value range, the triggered key switch is determined in combination with the voltage conditions of the voltage output terminal 110 of the high-level scan line 10 and the multiple output lines 11.

[0066] It should be noted that in step S1, the high level of the first voltage terminals 100 of the plurality of scan lines 10 is sequentially supplied for a preset time period, and it is not necessary to supply the high level of the plurality of scan lines 10 in the same order. Figure 4 , the total time from the first scan line 10 being passed to the last scan line 10 being passed to the high level is a scan cycle T1, then it is only necessary to pass the high level to all scan lines 10 within one scan cycle T1, and it is not necessary to follow a certain 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 passed to the high level in sequence, and in the second scan cycle, the first scan line 10a, the third scan line 10c and the second scan line 10b can be passed to the high level in sequence. Of course, in order to simplify the program, it is optional to always pass the high level to each scan line in the same order in each scan cycle T1, for example Figure 4 In the embodiment, a high level is applied to the first scan line 10a, the second scan line 10b and the third scan line 10c in sequence.

[0067] In step S2 , voltage detection is performed on the voltage output terminals 110 of all output lines 11 during the time period when each scan line 10 is at a high level, so as to ensure that no key is missed in the detection.

[0068] It can be understood that the scanning period T1 is short enough. Within the extremely short scanning period, all the scanning lines 10 can be passed to a high level at least once, and the output voltages of all the output lines 11 are detected when any scanning line 10 inputs a high level, so that under normal operation, no matter when the key is pressed by a person's hand, it can be detected that the key is pressed.

[0069] Furthermore, to ensure that the LEDs continuously emit light, the duration of scan cycle T1 is set so that the flickering of the LEDs is not perceptible to the naked eye. It is understood that when a high level is input to a scan line 10, the LEDs on that scan line 10 will illuminate, while the other LEDs will remain silent. Therefore, the LEDs do not emit light continuously, but rather intermittently. When the intermittent period is short enough, the flickering of the LEDs will be imperceptible to the naked eye, thereby ensuring that the LEDs appear to be constantly on.

[0070] Optionally, the interval time between the same light-emitting diode lighting up is no more than 41.6 ms, so that the human eye perceives it as constantly on and cannot detect flickering.

[0071] Optionally, the scanning period T1 is no longer than 41.6 ms, which is beneficial for the light emitting diode to emit continuous light in a sensory sense and ensures that under normal operation, it can be detected that the key is pressed no matter when the key is pressed by a human hand.

[0072] In order to ensure that there is sufficient time to detect the voltage of the output line 11 after the scan line 10 is powered on, in step S1, the time for each high level input of any of the scan lines 10 is not less than 50 microseconds, so that there is sufficient time to detect the output line 11. Further, optionally, the time for each high level input of any of the scan lines 10 is not less than 100 microseconds. As a further improvement, in step S2, the voltage output terminal 110 of the output line 11 is detected after a preset time period after the high level is input to the scan line 10. Generally, the voltage level will fluctuate (lasting about 10 to 30 microseconds) within a period of time after the high level is input to the scan line 10. Therefore, performing voltage detection after a preset time period after the high level is input to the scan line 10 can make the voltage of the voltage output terminal 110 more stable and the detection result more accurate. Optionally, the length of the preset time period is greater than or equal to 30 microseconds, and can further be greater than or equal to 50 microseconds to ensure the accuracy of the detection result and avoid false detection caused by level jitter.

[0073] Optionally, step S3 includes the following steps:

[0074] S31. When the voltage signal at the voltage output terminal 110 of a certain output line 11 is detected to be within a preset amplitude range, the scanning line 10 that is simultaneously receiving a high voltage level is obtained. For ease of description, the output line 11 corresponding to the voltage output terminal 110 for which the voltage signal is detected to be within the preset amplitude range is referred to as a qualified output line 11.

[0075] S32. Identify the key switch connected between the output line 11 that meets the requirements and the scan line 10 that is simultaneously connected to the high level. This key switch is the triggered key switch.

[0076] It is understandable that the position information of each key switch corresponding to the scan line 10 and the output line 11 has been recorded and stored in advance. Therefore, when it is known that the output line 11 detected the voltage and the scan line 10 is connected to the high level at the same time, the position information of the key switch can be obtained, thereby identifying which key switch is triggered. The position information of the key switch corresponds to the position of the pressed key.

[0077] It is understood that the keyboard has a light-emitting unit that can illuminate the keys to achieve backlighting. The light-emitting unit is located below the keys and emits light toward the side where the keys are located. Generally, each key is provided with a corresponding light-emitting unit. The backlight color can be monochrome or multicolored. When the backlight color is monochrome, for example, it can be white, red, green, blue or other colors. In this case, the light-emitting unit can include only one light-emitting diode, which is connected in series. Figure 1 and Figure 3In the circuit shown, light emission is achieved. When the backlight color is multicolored, a richer color effect can be achieved. For example, the color can gradually change, making the backlight effect more cool. In this case, the light-emitting unit may include at least two light-emitting diodes that emit light of different colors. The different colored light-emitting diodes can emit a single color alone or mix to emit new colors, thereby achieving a richer color.

[0078] The present invention further provides a key input device, which includes any one of the keyboard backlight circuits described above. The key input device may be, for example, a keyboard, such as a keyboard of a mobile phone or a computer.

[0079] The key input device includes a key circuit board, such as Figure 5 As shown, the key circuit board includes a first circuit board 40 and a second circuit board 41 spaced apart from each other, and a spacer layer 42 connected between 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 any). The second circuit board 41 is provided with a scanning line 10, a light-emitting diode 46 and a first resistor (not shown). Conductive lines (such as silver paste lines) can be set on the first circuit board 40 and the second circuit board 41 to form the scanning line 10 and the output line 11.

[0080] The key switch is connected between the first circuit board 40 and the second circuit board 41. Figure 5 As shown, the key switch includes a first contact 430 located on a first circuit board 40 and electrically connected to the output line 11, and a second contact 431 located on a second circuit board 41 and electrically connected to the scan line 10. The two contacts are spaced apart from each other, and a spacer layer 42 is provided with a cavity 420 through which the first contact 430 and the second contact 431 are exposed. A reset member 44 and a key 45 are correspondingly disposed above the key switch. The reset member 44 can be made of an elastic material such as rubber or silicone. When the key 45 is pressed, it depresses the reset member 44 and the key switch, causing the first contact 430 and the second contact 431 to contact, thereby connecting the scan line 10 and the output line 11. When the key 45 is released, the key 45 is reset by the elastic force of the reset member 44, disconnecting the scan line 10 and the output line 11.

[0081] The light emitting diode 46 is provided on the second circuit board 41, and a avoidance hole 400 is provided on the spacer layer 42 and the first circuit board 40 for exposing the light emitting diode 46. The light emitting diode 46 is provided in the avoidance hole 400, and its light can be emitted toward the key 45. In some embodiments, a light-transmitting area 450 made of a transparent material is provided on the key 45. The light-transmitting area 450 can, for example, be consistent with the letters / graphics marked on the key 45, so that the light of the light emitting diode 46 can illuminate the letters / graphics, which is more beautiful. The key 45 can also be set to be fully transparent. In this case, the part of the key 45 other than the part marked with the letters / graphics forms the light-transmitting area 450 (that is, the light-transmitting area 450 includes the case where the key 45 is partially transparent or fully transparent). In other embodiments, refer to Figure 6 The inner surface of the button 45 is provided with a reflective layer 451, and the reflective layer 451 has a reflective surface that reflects the light of the light-emitting diode 46. The area around the button 45 is illuminated by the reflected light, thereby improving the 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 can be directly used as the reflective surface.

[0082] 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 all be arranged on the second circuit board 41 , and of course can also be arranged on the first circuit board 40 .

[0083] Optionally, the first circuit board 40 and the second circuit board 41 are both thin film circuits.

[0084] In the present invention, only two layers of circuit boards are needed to realize 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 made smaller. In this way, the key input device can also be made smaller. For products such as notebooks that have high requirements for lightness and thinness, the thickness of the notebook can be effectively reduced, thereby improving the competitiveness of the product.

[0085] The present invention also provides 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.

[0086] The present invention also provides a processor-readable storage medium for storing processor-executable instructions. When the processor-executable instructions are loaded and executed by the processor, any of the aforementioned keyboard backlight circuit driving methods can be implemented. It is understood that a key input device and / or electronic device may include the processor-readable storage medium.

[0087] It should be noted that, in the absence of conflict, the various embodiments in this document can be combined with each other to obtain more implementation plans.

[0088] The above is only a specific implementation of the present invention, and any other improvements made based on the concept of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A keyboard backlight circuit with integrated key detection function, characterized in that: include: A plurality of scan lines (10), wherein the plurality of scan lines (10) are arranged at intervals, wherein the scan lines (10) have a main line (102) and a plurality of parallel branch lines (103) connected to the main line (102), wherein the main line (102) has a first voltage terminal (100), and the branch lines (103) have a second voltage terminal (101), and a light-emitting diode and a first resistor are sequentially arranged in series between a connection position between the branch lines (103) and the main line (102) and the second voltage terminal (101), wherein the light-emitting diode is used to realize keyboard backlighting and enables current to be unidirectionally conducted toward the first resistor; and, A plurality of output lines (11) are arranged at intervals and staggered with the scan lines (10) to form a matrix circuit. The output lines (11) have voltage output terminals (110) and a plurality of switch circuits (12) respectively connected to the branch lines (103) of the plurality of scan lines (10). Each branch line (103) is provided with a corresponding switch circuit (12). The switch circuit (12) is connected to a portion of the branch line (103) located between the light-emitting diode and the first resistor. The switch circuit (12) includes a key switch.

2. The keyboard backlight circuit with integrated key detection function according to claim 1, characterized in that: The first voltage terminal (100) and the voltage output terminal (110) are both connected to the IO interface of the chip; the chip inputs a driving voltage signal to the plurality of scanning lines (10) and detects the voltage signal of the voltage output terminal (110) of the output line (11); the second voltage terminal (101) is a ground voltage terminal.

3. The keyboard backlight circuit with integrated key detection function according to claim 1, wherein: The driving voltage applied to the first voltage terminal (100) is 5V, and the resistance of the first resistor is 100 to 1000 ohms; or, The driving voltage supplied to the first voltage terminal (100) is 3.3V, and the resistance of the first resistor is 30 to 500 ohms.

4. The keyboard backlight circuit with integrated key detection function as claimed in claim 1, characterized in that: The colors of the lights emitted by all the light emitting diodes are the same; or, the colors of the lights emitted by at least two light emitting diodes are different.

5. The keyboard backlight circuit with integrated key detection function according to any one of claims 1 to 4, characterized in that: The switch circuit (12) further includes a second resistor connected in series with the key switch.

6. The keyboard backlight circuit with integrated key detection function as claimed in claim 5, characterized in that: The resistance of the second resistor is greater than 0.2 times the resistance of the first resistor.

7. The keyboard backlight circuit with integrated key detection function as claimed in claim 5, characterized in that: The resistance of the second resistor is greater than or equal to 2 times the resistance of the first resistor and less than or equal to 10 times the resistance of the first resistor.

8. A key input device, characterized in that: A keyboard backlight circuit with integrated key detection function comprising the circuit as claimed in any one of claims 1 to 7.

9. The key input device according to claim 8, wherein: include: A first circuit board (40) is provided with the output line (11); A second circuit board (41) is provided with the scanning line (10), the light emitting diode and the first resistor; and A key switch, comprising 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), wherein the first contact (430) and the second contact (431) are arranged relative to each other with a distance therebetween; A reset member (44) and a key (45) are correspondingly provided above the key switch. The light-emitting diode is provided below the key (45) and is exposed on the first circuit board (40) to emit light toward the key (45). The first circuit board (40) is closer to the key (45) than the second circuit board (41).

10. The key input device according to claim 9, wherein: It also includes a spacer layer (42) connected between the first circuit board (40) and the second circuit board (41), wherein the spacer layer (42) and the first circuit board (40) are provided with a avoidance hole (400), and the light-emitting diode is located in the avoidance hole (400).

11. The key input device according to claim 9, wherein: The button (45) is provided with a light-transmitting area (450) for allowing light from the light-emitting diode to pass through; or, The inner wall of the button (45) is provided with a reflective surface.

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