Keyboard backlight circuit, driving method and key input device

Abstract

The invention discloses a keyboard backlight circuit integrated with a key detection function, a keyboard backlight circuit driving method 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 branch lines which are connected with the main line in parallel, the main line is provided with a first voltage end, and the main line is provided with a second voltage end; the branch line is provided with a second voltage end, 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 one direction; 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 invention relates to an information input device, and in particular to a keyboard backlight circuit with integrated key detection function, a keyboard backlight circuit driving method and a key input device. Background Art

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

[0003] In order to make the keyboard easy to use in a dark or dim environment, some keyboards have a backlight function, which illuminates the keys or the area around the keys through LEDs (light emitting diodes), so that users can identify the positions of the keys on the keyboard and can accurately perform key operations. The backlight function of the keyboard is realized by the backlight circuit of the keyboard. The backlight circuit is provided with light emitting diodes corresponding to the key positions, and the backlight function of the keyboard is realized by controlling the light emitting diodes to emit light.

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

[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, which leads to complex circuit layout, many circuit board layers or the need to stack multiple circuit boards, 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 and unable to meet the requirements of thinness and lightness of laptops.

[0007] The above contents are only used to help understand the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0008] The purpose of the present invention is to provide a keyboard backlight circuit with integrated key detection function, a keyboard backlight circuit driving method and a key input device, which can realize the keyboard backlight function and the anti-ghost key detection function and have a simple circuit structure.

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

[0010] A plurality of scan lines, the plurality of scan lines are arranged at intervals, the scan lines have a main line and a plurality of branch lines connected in parallel with the main line, the main line has a first voltage end, the branch line has a second voltage end, a light emitting diode and a first resistor connected in series are sequentially arranged between a connection position between the branch line and the main line and the second voltage end, the light emitting diode is used to realize keyboard backlight, and makes current unidirectionally conduct 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, and 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 a voltage signal at the voltage output terminal of the output line; the second voltage terminal is a ground voltage terminal.

[0013] Further, 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 light emitted by at least two light emitting diodes are different.

[0016] Furthermore, the switch circuit also 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 proposes a keyboard backlight circuit driving method, which is performed by the keyboard backlight circuit with integrated key detection function as described above, and the keyboard backlight circuit driving method comprises the following steps:

[0020] S1. sequentially pass a high level of a preset duration to the first voltage terminals of the plurality of scan lines, and pass a high level to only one first voltage terminal of the scan line at the same time;

[0021] S2. Detecting the voltage signal at the voltage output end of all the output lines during the high level period to determine whether the voltage is within a preset amplitude range;

[0022] S3. When it is detected that the voltage signal at a certain voltage output terminal is within a preset amplitude value range, the triggered key switch is determined based on the voltage conditions of the voltage output terminals of the scanning line with a high level and the plurality of output lines.

[0023] Furthermore, the total time from the first scanning line being supplied with a high level to the last scanning line being supplied with a high level is a scanning cycle, and the time of the scanning cycle is set so that the flickering of the light emitting diode cannot be recognized by naked eyes.

[0024] Furthermore, the scanning cycle time is no longer than 41.6 ms.

[0025] Furthermore, in the step S2, the voltage output end of the output line is detected after a preset time period after the high level is passed to the scan line.

[0026] Furthermore, step S3 includes the following steps:

[0027] S31. When the voltage signal at the voltage output end of a certain output line is detected to be within a preset amplitude range, a scanning line having a high level at the same time is obtained;

[0028] S32. Identify the key switch connected between the output line that meets the requirements and the scan line that is passed through a high level at the same time. The key switch is the triggered key switch. The output line that meets the requirements refers to the output line corresponding to the voltage output terminal whose detected voltage signal is within a preset amplitude value range.

[0029] In a third aspect, the present invention provides a key input device, comprising the keyboard backlight circuit with integrated key detection function as described above.

[0030] Furthermore, the key input device comprises:

[0031] A first circuit board is provided with the output line;

[0032] A second circuit board is provided with the scanning line, the light emitting diode and the first resistor; and

[0033] 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 arranged with a relative spacing;

[0034] 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, and the first circuit board is closer to the button than the second circuit board.

[0035] Furthermore, the key input device further comprises 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.

[0036] Furthermore, the button is provided with a light-transmitting area for allowing the light of the light-emitting diode to transmit; or,

[0037] The inner wall of the button is provided with a reflective surface.

[0038] Compared with the prior art, the present invention has the following beneficial effects: According to some embodiments of the present invention, the keyboard backlight circuit with integrated key detection function can realize the key detection and anti-ghost key functions while achieving the keyboard backlight effect by serially inserting a switch circuit in the keyboard backlight circuit, thereby simplifying the circuit structure and helping to reduce costs. At the same time, the simplified circuit structure can reduce the number of layers of the circuit board of the key output device, thereby helping to reduce the thickness of the key input device and realize the thinness of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a circuit diagram of a keyboard backlight circuit with integrated key detection function according to an embodiment of the present invention.

[0040] Figure 2 yes Figure 1 The circuit shown is a schematic diagram of preventing false detection.

[0041] Figure 3 This is a circuit diagram of a keyboard backlight circuit with integrated key detection function in an embodiment of the present invention. In the diagram, a second resistor is provided in the switch circuit.

[0042] Figure 4 This is a timing diagram of passing a high level to each scanning line during key detection in an embodiment of the present invention, and two scanning cycles are shown in the figure.

[0043] Figure 5 It is a structural schematic diagram of a key input device in an embodiment of the present invention.

[0044] Figure 6 It is a structural schematic diagram of a key input device in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, 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 is to 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 structures related to the present application are shown in the accompanying drawings, rather than all structures. 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.

[0046] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0047] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0048] The present invention proposes a keyboard backlight circuit with integrated key detection function (hereinafter referred to as 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.

[0049] like Figure 1 As shown, a keyboard backlight circuit corresponding to an embodiment of the present invention includes a plurality of scan lines 10 and a plurality of output lines 11. The plurality of scan lines 10 are arranged at intervals, and the plurality of output lines 11 are also arranged at intervals. The scan lines 10 and the output lines 11 are arranged in an interlaced manner to form a matrix circuit. Figure 1 As shown, Figure 1 The 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.

[0050] It should be noted that, herein, "plurality" or "multiple" or similar expressions indicate that the number is at least two, that is, "plurality" means two or more, therefore, in other embodiments, the number of the scan lines 10 and the output lines 11 may be two or more than three. It should be further noted that, although in the illustrated embodiment, the number of the scan lines 10 and the output lines 11 are the same, this is not necessarily the case, and the numbers of the two may be different, for example, one of them is two and the other is three, and so on.

[0051] 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 scanning 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, and 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 diode allows the current to be unidirectionally conducted toward the second voltage terminal 101, that is, the current introduced into the first voltage terminal 100 flows into the positive electrode of the light emitting diode, then flows out from the negative electrode of the light emitting diode, and flows through the first resistor, so that the light emitting diode emits light. It can be understood that due to the unidirectional conduction characteristic of the light emitting diode, the current cannot flow from the negative electrode to the positive electrode.

[0052] The output line 11 has a voltage output terminal 110 and a plurality of switch circuits 12 respectively connected to the plurality of scan lines 10. Specifically, the plurality of switch circuits 12 are respectively connected to the branch lines 103 of the plurality of scan lines 10. More specifically, the switch circuit 12 is connected to the portion of the branch line 103 between the light emitting diode and the first resistor. The plurality of switch circuits 12 of the same output line 11 are connected in parallel. Each branch line 103 is correspondingly provided with a switch circuit 12. The switch circuit 12 includes a key switch, Figure 1 SW1 to SW9 marked in are push switches, which correspond to the position of the key (usually located below the key). When the key is pressed, the key will move downward to trigger the key switch to close, making the switch circuit 12 conductive. Conversely, when the key switch is released, the key is reset, making the key switch disconnected.

[0053] The first voltage terminal 100 of the scan 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 scan line 100, the light-emitting diode is driven to emit light. The light-emitting diode can illuminate the key, thereby playing the role of 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 displaying the letter can be set to be 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.

[0054] It can be understood that when the key switch (for example, SW1) is pressed and the first voltage terminal 100 of the scan line 10 (for example, the first scan line 10a) connected thereto is applied with a high-level driving voltage, 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 there is a pressed key switch.

[0055] 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 may be greater than 0V, that is, as long as a voltage of a certain magnitude is detected, it is considered that the key is pressed.

[0056] In some embodiments, in order to reduce the 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 size. The voltage value obtained by calculation or actual measurement can be used as a basis for judging whether there is a voltage in the preset range at the voltage output terminal 110. 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 magnitude 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 with a voltage magnitude greater than or equal to a fixed value. The voltage signal may be smaller than a certain amplitude of a calculated or measured voltage value, or may be equal to a calculated or measured voltage value.

[0057] 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 to achieve key detection.

[0058] 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, and 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 switch SW1 and the key switch SW2 are pressed at the same time. Similarly, the position of the pressed key can be determined by combining the voltage conditions of the voltage output terminals 110 of the scan line 10 and the plurality of output lines 11 to which a high level is applied, thereby realizing key detection.

[0059] Since the light emitting diode is connected in series in the scanning line 10, the unidirectional conduction characteristic of the light emitting diode can be used to achieve the effect of anti-ghosting. For example, when the current is passed through the second scanning line 10b (i.e., the high-level driving voltage is passed through), and the key switches SW1, SW2 and SW4 are pressed at the same time, at this time, only the voltage output end of the first output line 11a can detect the voltage within the preset amplitude value range. Due to the unidirectional conduction effect of the light emitting diode D1, the current cannot pass through 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 being pressed. Therefore, the above-mentioned keyboard backlight circuit can prevent false detection.

[0060] It is understandable that, through the above circuit structure design, while achieving the light-emitting effect of the key, it can also play an anti-ghosting function, thereby simplifying the circuit structure and helping to reduce costs. At the same time, the simplified circuit structure can reduce the number of layers of the circuit board of the key output device, thereby helping to reduce the thickness of the key input device and achieve lightweight electronic equipment.

[0061] 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 driving voltage signals to multiple scanning lines according to control signals, and detect the voltage signal of the voltage output terminal 110 of the output line 11, thereby realizing backlight and key detection.

[0062] Optionally, the second voltage terminal 101 is a ground voltage terminal.

[0063] 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 about 5V. By setting the resistance of the first resistor to 100-1000 ohms, the current flowing through the light-emitting diode can be 1-10mA, which meets the current required for most light-emitting diodes used in keyboards to emit light. In other embodiments, the driving voltage input to the first voltage terminal 100 is about 3.3V. At this time, the resistance of the first resistor can be selected to be 30-500 ohms so that the light-emitting diode can emit light reliably.

[0064] 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.

[0065] In some embodiments, Figure 3As shown, the switch circuit 12 also includes a second resistor connected in series with the key switch. Figure 3 R10 to R18 are the second resistors, and the resistance of the second resistor 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, and the resistance after the parallel connection is smaller than the resistance of the single first resistor, 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 at the same time. When the resistance values ​​of the first resistors R1 and R4 are the same, the resistance value 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 the service life.

[0066] 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 of the same output line 10 are pressed simultaneously, due to the presence of the second resistor, the resistance of the resistor that is finally divided with the light emitting diode will decrease relatively smaller, thereby ensuring the stability of the current flowing through the light emitting diode when the key is pressed, reducing the increase in the current, which is conducive to the reliable light emission of the light emitting diode, and the light emission effect is more consistent and stable, and it is also conducive to extending its service life. For example, when the first voltage terminal 100 of the first scanning line 10a inputs a high level 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 resistance after parallel connection will be greater than the resistance after only R1 and R4 are connected in parallel, reducing the increase in the current flowing through the light emitting diode.

[0067] In order to further ensure the stability of the light emitting diode, the resistance of the second resistor can be greater than or equal to 1 times, 2 times, 3 times, 4 times, 5 times 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 amplitude of the current flowing through the light emitting diode is smaller, and no obvious optical and electrical effects are caused on the light emitting diode, thereby effectively ensuring the stability of the light emitting diode and the reliability of use.

[0068] 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 10 times less than the resistance of the first resistor is beneficial to improving the accuracy of the detection value.

[0069] Optionally, the first resistor and the second resistor may be a common resistor, a carbon ink resistor, a silver paste printed resistor, or other resistors that can be used for thin film circuits.

[0070] The color of the light emitted by the LED is not limited, for example, it can be white, red, blue or green. Optionally, the color of the light emitted by all the LEDs is the same, or the light colors of at least two LEDs are different, so as to produce a richer lighting effect. The colors of the LEDs at different positions can be set as needed.

[0071] Next, a method for backlight driving using the keyboard backlight circuit described above is introduced.

[0072] The keyboard backlight circuit driving method comprises the following steps:

[0073] S1. A high level of a preset duration is applied to the first voltage terminals 100 of the plurality of scan lines 10 in sequence, and a high level is applied to only one first voltage terminal 100 of the scan line 10 at a time, that is, a high level is applied to at most one scan line 10 at a time.

[0074] S2. Detect the voltage signals of the voltage output terminals 110 of the multiple output lines 11 during the time period when the high level is applied, and determine whether there is a voltage signal whose voltage magnitude is within the preset amplitude value range, that is, determine whether the voltage magnitude of the detected voltage signal is within the preset amplitude value range.

[0075] 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.

[0076] It should be noted that in step S1, the high level of the preset duration is sequentially applied to the first voltage terminals 100 of the plurality of scan lines 10, and it is not necessary to apply the high level to 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 high level 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 a scan cycle T1, and it is not necessary to follow a certain order. For example, the first scan cycle T1 can pass the high level to the first scan line 10a, the second scan line 10b and the third scan line 10c in turn, and the second scan cycle can pass the high level to the first scan line 10a, the third scan line 10c and the second scan line 10b in turn. Of course, in order to simplify the program, it is optional that each scan cycle T1 always passes the high level to each scan line in the same order, 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.

[0077] In step S2, during the time period when each scanning line 10 is at a high level, voltage detection is performed on the voltage output terminals 110 of all output lines 11 to ensure that no key is missed in the detection.

[0078] It can be understood that the scanning period T1 is short enough that all the scanning lines 10 can be passed to a high level at least once within the extremely short scanning period, 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 a key is pressed by hand, it can be detected that the key is pressed.

[0079] Furthermore, in order to ensure that the light-emitting diode can continuously emit light, the time of the scanning cycle T1 is set so that the naked eye cannot recognize the flickering of the light-emitting diode. It can be understood that when a certain scanning line 10 inputs a high level, the light-emitting diode on the scanning line 10 will emit light, while other light-emitting diodes will not emit light. Therefore, the light-emitting diode does not emit light continuously, but emits light intermittently. When the intermittent time is short enough, the flickering of the light-emitting diode will not be detected by the naked eye, thereby ensuring that the light-emitting diode can be displayed as always on in external performance.

[0080] Optionally, the interval time between the same light emitting diode lighting up is no more than 41.6 ms, so that human eyes perceive it as being constantly on and cannot detect flickering.

[0081] Optionally, the scanning cycle T1 is no longer than 41.6 ms, which helps the light emitting diode to emit continuous light to the senses and ensures that under normal operation, it can be detected that the key is pressed no matter when the key is pressed by hand.

[0082] In order to allow enough time to detect the voltage of the output line 11 after the scan line 10 is powered on, in the step S1, the time for any of the scan lines 10 to input a high level each time is not less than 50 microseconds, so that there is enough time to detect the output line 11. Further, optionally, the time for any of the scan lines 10 to input a high level each time is not less than 100 microseconds. As a further improvement, in the step S2, the voltage output terminal 110 of the output line 11 is detected after a preset time period after the scan line 10 is fed with a high level. Generally, within a period of time after the scan line 10 is fed with a high level, the level will jitter (lasting about 10 to 30 microseconds). Therefore, the voltage output terminal 110 is detected after a preset time period after the scan line 10 is fed with a high level, which can make the voltage 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 be further selected to be greater than or equal to 50 microseconds, so as to ensure the accuracy of the detection result and avoid false detection caused by level jitter.

[0083] Optionally, step S3 includes the following steps:

[0084] S31. When it is detected that the voltage signal of the voltage output terminal 110 of a certain output line 11 is within the preset amplitude value range, the scanning line 10 that is passed through the high level at the same time is obtained. For the convenience of description, the output line 11 corresponding to the voltage output terminal 110 whose voltage signal is within the preset amplitude value range is called the output line 11 that meets the requirements;

[0085] S32. Identify the key switch connected between the output line 11 that meets the requirements and the scan line 10 that is at a high level at the same time. The key switch is the triggered key switch.

[0086] It can be understood 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 that detects the voltage and the scan line 10 that passes the high level at the same time are detected, 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.

[0087] 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 colorful. When the backlight color is monochrome, for example, it can be white, red, green, blue or other colors. At this time, 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 realized. When the backlight color is colorful, richer color effects can be achieved, for example, the color can change gradually, making the backlight effect more cool. At this time, 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 one color alone, or they can be mixed to emit new colors, thereby making the colors richer.

[0088] 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.

[0089] 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 which are 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 arranged on the first circuit board 40 and the second circuit board 41 to form the scanning line 10 and the output line 11.

[0090] 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 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 with a relative spacing, and the spacing 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 key 45 are correspondingly arranged above the key switch. The reset member 44 can be made of elastic materials such as rubber or silicone. When the key 45 is pressed, the key 45 presses the reset member 44 and the key 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 key 45 is released, the key 45 is reset under the elastic force of the reset member 44, and the scan line 10 and the output line 11 are disconnected.

[0091] The light emitting diode 46 is arranged on the second circuit board 41, and a avoidance hole 400 for exposing the light emitting diode 46 is opened on the spacer layer 42 and the first circuit board 40. The light emitting diode 46 is arranged 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 transparent material is provided on the key 45. The light-transmitting area 450 can 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 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 A reflective layer 451 is provided on the inner surface of the key 45. The reflective layer 451 has a reflective surface that reflects the light of the light-emitting diode 46. The area around the key 45 is illuminated by the reflected light to improve the aesthetics. In other embodiments, if the inner surface of the key 45 itself has a good reflective effect, the reflective layer 451 may not be provided, and the inner surface of the key 45 can be directly used as the reflective surface.

[0092] It is understandable that when the light-emitting unit includes a plurality of light-emitting diodes, the other diodes and the corresponding control circuit and the third resistor can be arranged on the second circuit board 41 , and of course can also be arranged on the first circuit board 40 .

[0093] Optionally, the first circuit board 40 and the second circuit board 41 are both thin film circuits.

[0094] 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.

[0095] The present invention also provides an electronic device, which includes any of the keyboard backlight circuits described above or includes 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.

[0096] The present invention also proposes a processor-readable storage medium, which is used to store processor-executable instructions. When the processor-executable instructions are loaded and executed by the processor, any of the keyboard backlight circuit driving methods described above can be implemented. It can be understood that the key input device and / or electronic device can include the processor-readable storage medium.

[0097] 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.

[0098] The above are only specific embodiments of the present invention, and any other improvements made based on the concept of the present invention are considered to be within the protection scope of the present invention.

Claims

1. A keyboard backlight circuit with integrated key detection function, characterized in that: include: A plurality of scanning lines (10), wherein the plurality of scanning lines (10) are arranged at intervals, wherein the scanning lines (10) have a main line (102) and a plurality of branch lines (103) connected in parallel to the main line (102), wherein the main line (102) has a first voltage end (100), and the branch line (103) has a second voltage end (101), and a light-emitting diode and a first resistor connected in series are sequentially arranged between a connection position between the branch line (103) and the main line (102) and the second voltage end (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), the plurality of output lines (11) are arranged at intervals and are arranged in an alternating manner with the scanning lines (10) to form a matrix circuit, the output lines (11) having a voltage output terminal (110) and a plurality of switch circuits (12) respectively connected to the branch lines (103) of the plurality of scanning lines (10), each branch line (103) being provided with a corresponding switch circuit (12), the switch circuit (12) being connected to a portion of the branch line (103) located between the light emitting diode and the first resistor, and the switch circuit (12) comprising a key switch.

2. The keyboard backlight circuit with integrated key detection function as claimed in 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 as claimed in claim 1, characterized in that: 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 light emitted by all the light emitting diodes are the same; or, the colors of light 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) also 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 value of the second resistor is greater than or equal to 2 times the resistance value of the first resistor, and less than or equal to 10 times the resistance value of the first resistor.

8. A keyboard backlight circuit driving method, characterized in that: The method is implemented by the keyboard backlight circuit with integrated key detection function as claimed in any one of claims 1 to 7, and the keyboard backlight circuit driving method comprises the following steps: S1. sequentially passing a high level of a preset duration to the first voltage ends (100) of the plurality of scanning lines (10), and passing a high level to only the first voltage end (100) of one scanning line (10) at the same time; S2. Detecting the voltage signal of the voltage output terminal (110) of all the output lines (11) during the period of high level, and determining whether the voltage is within a preset amplitude range; S3. When it is detected that the magnitude of the voltage signal of a certain voltage output terminal (110) is within a preset amplitude value range, the triggered key switch is determined in combination with the voltage conditions of the voltage output terminals (110) of the scanning line (10) passing a high level and the plurality of output lines (11).

9. The keyboard backlight circuit driving method according to claim 8, characterized in that: The total time from the first scanning line (10) being supplied with a high level to the last scanning line (10) being supplied with a high level is a scanning cycle, and the time of the scanning cycle is set so that the flickering of the light emitting diode cannot be recognized by naked eyes.

10. The keyboard backlight circuit driving method according to claim 9, characterized in that: The scanning cycle time is no longer than 41.6 ms.

11. The keyboard backlight circuit driving method according to claim 9, characterized in that: In the step S2, the voltage output end (110) of the output line (11) is detected after a preset period of time after a high level is applied to the scan line (10).

12. The keyboard backlight circuit driving method according to any one of claims 8 to 11, characterized in that: The step S3 comprises the following steps: S31. When it is detected that the voltage signal of the voltage output terminal (110) of a certain output line (11) is within a preset amplitude value range, a scanning line (10) that is high-level at the same time is obtained; S32. Identify a key switch connected between an output line (11) that meets the requirements and a scan line (10) that is simultaneously supplied with a high level, the key switch being the triggered key switch, and the output line (11) that meets the requirements refers to the output line (11) corresponding to the voltage output terminal (110) whose detected voltage signal is within a preset amplitude value range.

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

14. The key input device according to claim 13, characterized in that: include: A first circuit board (40) 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 spacing therebetween; A reset member (44) and a key (45) are correspondingly arranged above the key switch; the light emitting diode is arranged 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).

15. The key input device according to claim 14, characterized in that: It also includes a spacing layer (42) connected between the first circuit board (40) and the second circuit board (41), the spacing layer (42) and the first circuit board (40) are provided with an avoidance hole (400), and the light-emitting diode is located in the avoidance hole (400).

16. The key input device according to claim 14, characterized in that: The button (45) is provided with a light-transmitting area (450) for allowing the light of the light-emitting diode to transmit; or, The inner wall of the button (45) is provided with a reflective surface.

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