Keyboard circuit with both anti-ghosting and backlighting functions

Abstract

A keyboard circuit combining anti-ghosting and backlighting functions includes a switching unit and a scanning unit. The switching unit includes multiple main drive lines, multiple auxiliary drive lines, multiple sensing lines, and multiple switch modules. Each switch module has a switch element, a current-limiting resistor corresponding to the respective switch element, and a light-emitting diode electrically connected to the respective switch element and the respective current-limiting resistor. The scanning unit includes a first scanning module electrically connected to the main drive lines, a second scanning module electrically connected to the auxiliary drive lines, and a detection module electrically connected to the sensing lines. The detection module receives an analog voltage value via its respective detection pin and, in conjunction with the level signals output by the first and second scanning modules, jointly determines the conduction status of the switches.

Description

Technical Field

[0001] The present invention relates to a keyboard circuit, and in particular to a keyboard circuit with both anti-ghosting and luminous functions. Prior Art

[0002] An input device, as shown in Taiwan Patent Certificate No. M403696, includes a switch module, a comparator, a switching unit, and a processing module. The switch module includes a plurality of drive lines that receive a plurality of drive signals, a plurality of sensing lines, a plurality of switches, and a plurality of resistors. The comparator includes a first input terminal, a second input terminal that receives a reference signal, and an output terminal that outputs a comparison signal. The switching unit is controlled by a set of control signals to electrically connect at least one of the sensing lines to the first input terminal of the comparator. The processing module is configured to set at least one of the drive signal, the reference signal, and the set of control signals so that the comparison signal indicates whether at least one of all switches is conducting, whether at least one of multiple switches is conducting, or whether a single switch is conducting, thereby preventing the generation of so-called "ghost keys."

[0003] However, as time goes by, people have begun to desire to add a lighting function to these existing input devices to facilitate use in low-light environments. Furthermore, installing a backlight module on the bottom side of these existing input devices would significantly increase the overall thickness. Clearly, even with the backlight module installed, the overall thickness of these existing input devices still needs to be improved. Summary of the Invention

[0004] Therefore, the purpose of the present invention is to provide a keyboard circuit that can overcome the above-mentioned shortcomings and has both anti-ghosting and lighting functions.

[0005] Therefore, the keyboard circuit of the present invention, which has both anti-ghosting and lighting functions, includes a switch unit and a scanning unit. The switch unit includes a plurality of main drive lines, a plurality of auxiliary drive lines, a plurality of sensing lines, and a plurality of switch modules. Each switch module has a switch element, a current-limiting resistor corresponding to each switch element, and a light-emitting diode electrically connecting each switch element and each current-limiting resistor. One end of each switch element is electrically connected to each sensing line, one end of each current-limiting resistor is electrically connected to each main drive line, the positive end of each light-emitting diode is electrically connected to the other end of each switch element and the other end of each current-limiting resistor, and the negative end of each light-emitting diode is electrically connected to each auxiliary drive line. The scanning unit includes a first scanning module electrically connected to the main driving lines, a second scanning module electrically connected to the auxiliary driving lines, and a detection module electrically connected to the sensing lines, the first scanning module, and the second scanning module. The first scanning module has a plurality of first scanning pins electrically connected to the main driving lines, the second scanning module has a plurality of second scanning pins electrically connected to the auxiliary driving lines, and the detection module has a plurality of detection pins electrically connected to the sensing lines. The detection module is used to receive an analog voltage value via each of the detection pins.

[0006] The present invention has the following advantages: the first scanning module sequentially outputs the high-level signal at one of the first scanning pins, and the second scanning module sequentially outputs the low-level signal at one of the second scanning pins. Furthermore, the reverse cutoff and forward conduction characteristics of the light-emitting diodes in the switch modules are utilized to allow the detection module to detect and receive the respective analog voltage values ​​at different timings, thereby determining the conduction status of the switch elements, thereby jointly realizing the anti-ghosting function and the lighting function. Simple diagram description

[0007] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an embodiment of a keyboard circuit having both anti-ghosting and luminous functions of the present invention; Figure 2 is a block diagram of this embodiment; Figure 3 is a block diagram of this embodiment; and FIG4 is a block diagram of this embodiment. Implementation Method

[0008] 1 , an embodiment of a keyboard circuit with both anti-ghosting and lighting functions according to the present invention includes a switch unit 1 and a scanning unit 2 .

[0009] The switch unit 1 includes a plurality of main drive lines 11, a plurality of auxiliary drive lines 12 cooperating with the main drive lines 11, a plurality of sensing lines 13 cooperating with the main drive lines 11, and a plurality of switch modules 14. To briefly introduce the structure of this embodiment, the following description will use two main drive lines 11, two auxiliary drive lines 12, two sensing lines 13, and four switch modules 14 as an example unless otherwise specified. However, in variations of this embodiment, the number of main drive lines 11, auxiliary drive lines 12, sensing lines 13, and switch modules 14 can be adjusted as needed.

[0010] Each switch module 14 includes a switch element 141, a current-limiting resistor 142 corresponding to each switch element 141, and a light-emitting diode 143 electrically connected to each switch element 141 and each current-limiting resistor 142. One end of each switch element 141 is electrically connected to each sensing line 13, one end of each current-limiting resistor 142 is electrically connected to each main drive line 11, the positive end of each light-emitting diode 143 is electrically connected to the other end of each switch element 141 and the other end of each current-limiting resistor 142, and the negative end of each light-emitting diode 143 is electrically connected to each auxiliary drive line 12. Each light-emitting diode 143 is used to emit light in response to the scanning unit 2. That is, each light-emitting diode 143 begins to conduct and emit light when it is in a forward bias.

[0011] The scanning unit 2 includes a first scanning module 21 electrically connected to the main driving lines 11, a second scanning module 22 electrically connected to the auxiliary driving lines 12, and a detection module 23 electrically connected to the sensing lines 13, the first scanning module 21, and the second scanning module 22. In this embodiment, the scanning unit 2 is implemented by a processor and a computer-readable medium electrically connected to the processor and storing a plurality of program instructions.

[0012] The first scanning module 21 includes a plurality of first scanning pins 211 electrically connected to the main driving lines 11. The first scanning module 21 is configured to output a high-level signal via one of the first scanning pins 211. In this embodiment, the voltage of the high-level signal is not less than 3 volts and not greater than 5.25 volts. It is worth noting that the voltage of the high-level signal is adjusted accordingly based on the type of the light-emitting diodes 143. For example, if the LEDs 143 are red diodes, their junction voltage is usually not less than 1.5 volts and not more than 2.5 volts (assuming it is 1.8 volts). The voltage value of the high-level signal is set to 3 volts, and with the current-limiting resistors 142 of 120 ohms (Ω), the LEDs 143 as red diodes can be normally lit. If the LEDs 143 are blue diodes, their junction voltage is usually not less than 2.5 volts and not more than 3.5 volts (assuming it is 3.3 volts). The voltage value of the high-level signal is set to 5 volts, and combined with the current-limiting resistors 142 of 170 ohms (Ω), the blue LEDs 143 can be properly illuminated. If the LEDs 143 are white LEDs, their junction voltage is typically not less than 2.75 volts and not more than 3.75 volts (assuming 3.6 volts). The voltage value of the high-level signal is set to 5 volts, and combined with the current-limiting resistors 142 of 140 ohms (Ω), the white LEDs 143 can be properly illuminated. Furthermore, the voltage value of the high-level signal and the resistance value of the current-limiting resistors 142 are adjusted accordingly based on the type of LEDs 143 to control the current flowing through the current-limiting resistors 142 (to be as close to 0.01 amperes as possible), thereby reducing the power consumption generated by the current-limiting resistors 142.

[0013] The second scan module 22 has a plurality of second scan pins 221 electrically connected to the auxiliary drive lines 12. The second scan module 22 is configured to output a low-level signal via one of the second scan pins 221. In this embodiment, the voltage of the low-level signal is not less than -0.1 volts and not greater than 0.1 volts, which is essentially the same as ground.

[0014] The detection module 23 has a plurality of detection pins 231 electrically connected to the sensing lines 13. The detection module 23 pre-stores a plurality of predetermined voltage values ​​indicating the junction voltages of the light-emitting diodes 143 and receives the voltage value of the high-level signal from the first scanning module 21. The detection module 23 is configured to receive an analog voltage value via each of the detection pins 231.

[0015] Referring to Figures 1 to 4 , in actual operation, for example, a user simultaneously presses the switch elements 141 located at the top left, bottom left, and bottom right of Figure 1 (three in total). During the pressing of the switch elements 141, the first scan module 21 sequentially outputs a high-level signal on one of the first scan pins 211, while the second scan module 22 sequentially outputs a low-level signal on one of the second scan pins 221. Consequently, the detection module 23 receives the respective analog voltage values ​​corresponding to different timings.

[0016] As shown in Figure 1, one of the first scan pins 211 of the first scan module 21 corresponding to the upper left switch 141 outputs the high-level signal, and one of the second scan pins 221 of the second scan module 22 corresponding to the upper left switch 141 outputs the low-level signal, causing the upper left LED 143 to be forward biased and begin to conduct and emit light (as indicated by the two-dot chain line). Furthermore, one of the detection pins 231 of the detection module 23 corresponding to the upper left switch 141 receives the analog voltage (as indicated by the one-dot chain line). At this point, the analog voltage is equal to the junction voltage of the upper left LED 143, i.e., the minimum voltage required for the upper left LED 143 to begin conducting under forward bias. This analog voltage varies depending on the color of the LED 143 and is no less than 1.5 volts and less than the voltage of the high-level signal. At this point, the detection module 23 averages the preset voltage value corresponding to the upper left LED 143 and the voltage value of the high-level signal to calculate an average threshold. The detection module 23 then compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it indicates that the analog voltage value is relatively closer to the preset voltage value, which means that the upper left switch 141 is pressed. Clearly, by receiving the analog voltage value through analog reading, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0017] As shown in FIG2 , one of the first scan pins 211 of the first scan module 21 corresponding to the switch element 141 on the upper right side outputs the high-level signal, and one of the second scan pins 221 of the second scan module 22 corresponding to the switch element 141 on the upper right side outputs the low-level signal, so that the light-emitting diode 143 on the upper right side starts to conduct and emit light under a forward bias (as shown by the two-dot chain line), and one of the detection pins 231 of the detection module 23 corresponding to the switch element 141 on the upper right side receives the analog voltage value (as shown by the one-dot chain line). At this time, since the upper right switch 141 is not conducting, no current is generated between the detection pin 231 corresponding to the upper right switch 141 and the first scan pin 211. Therefore, the analog voltage value is equal to the high-level signal output by the first scan pin 211 corresponding to the upper right switch 141. The analog voltage value is equivalent to the voltage value of the high-level signal. At this time, the detection module 23 averages the preset voltage value corresponding to the upper right light-emitting diode 143 and the voltage value of the high-level signal to calculate another average threshold value. The detection module 23 then compares the analog voltage value with the average threshold value. If the analog voltage value is greater than the average threshold value, it means that the analog voltage value is relatively closer to the voltage value of the high-level signal, which means that the upper right switch 141 is not pressed. Obviously, by receiving the analog voltage value in an analog reading manner by the detection module 23, the state represented by the analog voltage value can be determined more accurately.

[0018] As shown in Figure 3, one of the first scan pins 211 of the first scan module 21 corresponding to the lower left switch 141 outputs the high-level signal, and one of the second scan pins 221 of the second scan module 22 corresponding to the lower left switch 141 outputs the low-level signal, causing the lower left LED 143 to be forward biased and begin to conduct and emit light (as indicated by the two-dot chain line). Furthermore, one of the detection pins 231 of the detection module 23 corresponding to the lower left switch 141 receives the analog voltage (as indicated by the one-dot chain line). At this point, the analog voltage is equal to the junction voltage of the lower left LED 143, i.e., the minimum voltage required for the lower left LED 143 to begin conducting under forward bias. This analog voltage varies depending on the color of the LED 143 and is no less than 1.5 volts and less than the voltage of the high-level signal. At this point, the detection module 23 averages the preset voltage value corresponding to the lower left LED 143 and the voltage value of the high-level signal to calculate another average threshold. The detection module 23 then compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it indicates that the analog voltage value is relatively closer to the preset voltage value, which means that the lower left switch 141 is pressed. Clearly, by receiving the analog voltage value through analog reading, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0019] As shown in Figure 4, one of the first scan pins 211 of the first scan module 21 corresponding to the lower right switch 141 outputs the high-level signal, and one of the second scan pins 221 of the second scan module 22 corresponding to the lower right switch 141 outputs the low-level signal, causing the lower right LED 143 to be forward biased and begin to conduct and emit light (as indicated by the two-dot chain line). Furthermore, one of the detection pins 231 of the detection module 23 corresponding to the lower right switch 141 receives the analog voltage (as indicated by the one-dot chain line). At this point, the analog voltage is equal to the junction voltage of the lower right LED 143, i.e., the minimum voltage required for the lower right LED 143 to begin conducting under forward bias. This analog voltage varies depending on the color of the LED 143 and is no less than 1.5 volts and less than the voltage of the high-level signal. At this point, the detection module 23 averages the preset voltage value corresponding to the lower right LED 143 and the voltage value of the high-level signal to calculate another average threshold. The detection module 23 then compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it indicates that the analog voltage value is relatively closer to the preset voltage value, which means that the lower right switch 141 is pressed. Clearly, by receiving the analog voltage value through analog reading, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0020] It is worth mentioning that, in the process of studying the anti-ghosting function, the applicant has proposed a keyboard with an anti-ghosting function (as shown in Taiwan Patent Application No. 113112996), which includes a sensing unit, a detection unit, and a processing unit. The sensing unit includes a plurality of switch modules, each of which has a plurality of switch elements and a plurality of sensing resistors corresponding to the switch elements. The number of the switch elements and the sensing resistors is N, so that the resistance values ​​of the sensing resistors in each switch module form a sequence arranged from small to large. Except for the first item in the sequence, the value of any item in the sequence is greater than the sum of the values ​​of all items before any item in the sequence. The conduction status of the switch elements of each switch module causes each switch module to generate The invention relates to a method for detecting a keypad that is electrically connected to a plurality of switches, each of which has a corresponding equivalent resistance value. Furthermore, the detection unit receives a divided voltage value corresponding to each of the equivalent resistance values. Finally, the processing unit determines the conduction status of the switches based on the potential level values ​​to generate a key signal indicating which of the switches is pressed, thereby implementing an anti-ghosting function. Based on the technical feature of receiving the divided voltage value and combining it with the physical properties of the light-emitting diodes, the applicant proposes an analog reading method for receiving an analog voltage value of no less than 1.5 volts, thereby more accurately implementing the anti-ghosting function and simultaneously achieving the light-emitting function.

[0021] In summary, this embodiment has the following effects:

[0022] (1) The first scan module 21 sequentially outputs the high-level signal at one of the first scan pins 211, and the second scan module 22 sequentially outputs the low-level signal at one of the second scan pins 221. The reverse cutoff characteristics of the light-emitting diodes 143 in the switch modules 14 allow the detection module 23 to detect and receive the respective analog voltage values ​​at different timings, thereby determining the conduction status of the switch elements 141, thereby achieving an anti-ghosting function.

[0023] (2) The first scanning module 21, the second scanning module 22, the current-limiting resistors 142 and the light-emitting diodes 143 are used together to realize the light-emitting function, and the power consumption generated by the current-limiting resistors 142 is reduced by adjusting the voltage value of the high-level signal.

[0024] Therefore, the keyboard circuit of the present invention has both anti-ghosting and lighting functions, and integrates the anti-ghosting function and the lighting function, which can indeed achieve the purpose of the present invention.

[0025] However, the above is merely an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application and the content of the patent specification of the present invention are still within the scope of the patent of the present invention.

[0026] 1: Switch unit 11: Main drive line 12: Auxiliary drive line 13: Induction line 14: Switch module 141: switch 142: Current limiting resistor 143: Light-emitting diode 2: Scanning unit 21: First scanning module 211: First scan pin 22: Second scanning module 221: Second scan pin 23:Detection module 231: Detection pin

Claims

1. A keyboard circuit with both anti-ghosting and lighting functions, comprising: a switch unit including a plurality of main drive lines, a plurality of auxiliary drive lines, a plurality of sensing lines, and a plurality of switch modules, each switch module having a switch element, a current-limiting resistor corresponding to each switch element, and a light-emitting diode electrically connecting each switch element and each current-limiting resistor, one end of each switch element being electrically connected to each sensing line, one end of each current-limiting resistor being electrically connected to each main drive line, a positive end of each light-emitting diode being electrically connected to the other end of each switch element and the other end of each current-limiting resistor, and a negative end of each light-emitting diode being electrically connected to each auxiliary drive line; and a scanning unit including a first scanning module electrically connected to the main drive lines, a second scanning module electrically connected to the auxiliary drive lines, and a detection module electrically connected to the sensing lines, the first scanning module, and the second scanning module. The first scanning module has a plurality of first scanning pins electrically connected to the main driving lines, and is configured to output a high-level signal via one of the first scanning pins. The second scanning module has a plurality of second scanning pins electrically connected to the auxiliary driving lines, and is configured to output a low-level signal via one of the second scanning pins. The detection module pre-stores a plurality of preset voltage values ​​indicating the junction voltages of the light-emitting diodes and has a plurality of detection pins electrically connected to the sensing lines. The detection module is configured to receive the voltage value of the high-level signal from the first scanning module, average the respective preset voltage values ​​with the voltage value of the high-level signal to calculate an average threshold value, and then compare an analog voltage value received via each of the detection pins with the average threshold value to determine whether each of the switch elements is pressed.

2. The keyboard circuit with both anti-ghosting and lighting functions as claimed in claim 1, wherein: The voltage value of the high-level signal is not less than 3 volts and not greater than 5.25 volts, and the voltage value of the low-level signal is not less than -0.1 volt and not greater than 0.1 volt.

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