Keyboard circuit with anti-ghost key and light emitting function

Abstract

A keyboard circuit with ghost key prevention and light emitting 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 the respective switch element, and a light emitting diode electrically connected between 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 is configured to receive an analog voltage value via a respective detection pin and to determine a conduction state of the switch element in cooperation with level signals output by the first scanning module and the second scanning module.

Description

Technical Field

[0001] This invention relates to a keyboard circuit, and more particularly to a keyboard circuit that combines anti-ghosting and backlighting functions. Background Technology

[0002] An input device, as shown in Taiwan Patent Certificate No. TW M403696, includes a switch module, a comparator, a switching unit, and a processing module. The switch module includes multiple drive lines that each receive multiple drive signals, multiple sensing lines, multiple switches, and multiple 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 used to set at least one of the drive signal, the reference signal, and the control signal so that the comparison signal indicates whether at least one of all switches is on, whether at least one of multiple switches is on, or whether a single switch is on, to avoid generating so-called "ghost keys."

[0003] However, as technology advances, people have begun to desire the addition of backlighting to existing input devices for use in low-light environments. Furthermore, installing a backlight module on the bottom of existing input devices would significantly increase their overall thickness. Clearly, even with the installation of a backlight module, the overall thickness of existing input devices still has room for improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a keyboard circuit that overcomes the above-mentioned shortcomings and combines anti-ghosting and backlighting functions.

[0005] The present invention provides a keyboard circuit that combines anti-ghosting and backlighting functions, comprising a switching unit and a scanning unit. The switching unit includes multiple main drive lines, multiple auxiliary drive lines, multiple sensing lines, and multiple switching modules. Each switching module has a switching element, a current-limiting resistor corresponding to its respective switching element, and a light-emitting diode (LED) electrically connected to its respective switching element and its respective current-limiting resistor. One end of each switching element is electrically connected to its respective sensing line, one end of each current-limiting resistor is electrically connected to its respective main drive line, the positive terminal of each LED is commonly electrically connected to the other end of its respective switching element and the other end of its respective current-limiting resistor, and the negative terminal of each LED is electrically connected to its respective auxiliary drive line. 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 first scanning module, and the second scanning module. The first scanning module has multiple first scanning pins respectively electrically connected to the main drive lines, the second scanning module has multiple second scanning pins respectively electrically connected to the auxiliary drive lines, and the detection module has multiple detection pins respectively electrically connected to the sensing lines. The detection module is used to receive analog voltage values ​​via its respective detection pins.

[0006] The keyboard circuit of the present invention, which combines anti-ghosting and backlighting functions, wherein the first scanning module is used to output a high-level signal via one of the first scanning pins, and the second scanning module is used to output a low-level signal via one of the second scanning pins.

[0007] The keyboard circuit of the present invention, which combines anti-ghosting and light-emitting functions, includes a detection module for pre-storing multiple default voltage values ​​indicating the junction voltage of the light-emitting diodes, and for averaging the default voltage values ​​with the voltage values ​​of the high-level signals after receiving the voltage values ​​of the high-level signals from the first scanning module to calculate an average threshold, and then comparing the received analog voltage values ​​with the average threshold to determine whether the respective switches are pressed.

[0008] The keyboard circuit of the present invention, which combines anti-ghosting and backlighting functions, has a high-level signal voltage value of not less than 3 volts and not more than 5.25 volts, and a low-level signal voltage value of not less than -0.1 volts and not more than 0.1 volts.

[0009] The beneficial effects of the present invention are as follows: the first scanning module outputs the high-level signal sequentially at one of the first scanning pins, and the second scanning module outputs the low-level signal sequentially at one of the second scanning pins. Then, the reverse cutoff and forward conduction characteristics of the light-emitting diode in the switching module allow the detection module to detect and receive the respective analog voltage values ​​according to different timing sequences, thereby determining the conduction status of the switching device, thus jointly realizing the anti-ghosting function and the light-emitting function. Attached Figure Description

[0010] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, wherein:

[0011] Figure 1 This is a block diagram of an embodiment of the keyboard circuit of the present invention that combines anti-ghosting and backlighting functions;

[0012] Figure 2 This is a block diagram of the embodiment described;

[0013] Figure 3 This is a block diagram of the embodiment described;

[0014] Figure 4 This is a block diagram of the embodiment described. Detailed Implementation

[0015] See Figure 1 An embodiment of the keyboard circuit of the present invention, which combines anti-ghosting and light-emitting functions, includes a switching unit 1 and a scanning unit 2.

[0016] The switching unit 1 includes multiple main drive lines 11, multiple auxiliary drive lines 12 cooperating with the main drive lines 11, multiple sensing lines 13 cooperating with the main drive lines 11, and multiple switching modules 14. For the sake of brevity, unless otherwise specified, the following description uses two main drive lines 11, two auxiliary drive lines 12, two sensing lines 13, and four switching modules 14 as an example. However, in variations of this embodiment, the number of main drive lines 11, auxiliary drive lines 12, sensing lines 13, and switching modules 14 can be adjusted according to requirements.

[0017] Each switching module 14 has a switch 141, a current-limiting resistor 142 corresponding to its respective switch 141, and a light-emitting diode 143 electrically connected to its respective switch 141 and its respective current-limiting resistor 142. One end of each switch 141 is electrically connected to its respective sensing line 13, one end of each current-limiting resistor 142 is electrically connected to its respective main driving line 11, the positive terminal of each light-emitting diode 143 is commonly electrically connected to the other end of its respective switch 141 and its respective current-limiting resistor 142, and the negative terminal of each light-emitting diode 143 is electrically connected to its respective auxiliary driving line 12. Each light-emitting diode 143 is used to emit light corresponding to the scanning unit 2, that is, each light-emitting diode 143 will start to conduct and emit light when it is under forward bias.

[0018] The scanning unit 2 includes a first scanning module 21 electrically connected to the main drive line 11, a second scanning module 22 electrically connected to the auxiliary drive line 12, and a detection module 23 electrically connected to the sensing line 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 storing multiple programming instructions and electrically connected to the processor.

[0019] The first scanning module 21 has multiple first scanning pins 211 electrically connected to the main drive line 11. The first scanning module 21 outputs a high-level signal via one of the first scanning pins 211. In this embodiment, the voltage value of the high-level signal is not less than 3 volts and not more than 5.25 volts. It is worth mentioning that the voltage value of the high-level signal is adjusted according to the type of the light-emitting diode 143. For example, if the light-emitting diode 143 is a red light-emitting diode, its junction voltage is usually not less than 1.5 volts and not more than 2.5 volts (assumed to be 1.8 volts). The voltage value of the high-level signal is set to 3 volts, and with the 120 ohm (Ω) current-limiting resistor 142, the red light-emitting diode 143 can be lit normally. If the light-emitting diode 143 is a blue light-emitting diode, its junction voltage is usually not less than 2.5 volts and not more than 3.5 volts (assumed to be 3.3 volts). The high-level signal voltage is adjusted according to the type of the light-emitting diode 143. When the voltage value of the high-level signal is set to 5 volts and paired with the 170-ohm current-limiting resistor 142, the LED 143, which functions as a blue LED, can be lit normally. If the LED 143 is a white LED, its junction voltage is typically not less than 2.75 volts and not greater than 3.75 volts (assumed to be 3.6 volts). When the voltage value of the high-level signal is set to 5 volts and paired with the 140-ohm current-limiting resistor 142, the LED 143, which functions as a white LED, can be lit normally. On the other hand, the voltage value of the high-level signal and the resistance value of the current-limiting resistor 142 can be adjusted according to the type of LED 143 to control the current flowing through the current-limiting resistor 142 (trying to get as close to 0.01 amperes as possible), thereby reducing the power consumption generated by the current-limiting resistor 142.

[0020] The second scanning module 22 has a plurality of second scanning pins 221 respectively electrically connected to the auxiliary drive line 12. The second scanning module 22 is used to output a low-level signal via one of the second scanning pins 221. In this embodiment, the voltage value of the low-level signal is not less than -0.1 volts and not greater than 0.1 volts, which is essentially equivalent to ground.

[0021] The detection module 23 has multiple detection pins 231 electrically connected to the sensing line 13. The detection module 23 pre-stores multiple default voltage values ​​indicating the junction voltage of the light-emitting diode 143, and receives the voltage value of the high-level signal from the first scanning module 21. The detection module 23 is used to receive an analog voltage value via its respective detection pins 231.

[0022] See Figures 1 to 4 In actual operation, the user simultaneously presses the button located at... Figure 1Taking the upper left, lower left, and lower right switches 141 as an example (a total of three), when the upper left, lower left, and lower right switches 141 are pressed, the first scanning module 21 will sequentially output a high-level signal at one of the first scanning pins 211, while the second scanning module 22 will sequentially output a low-level signal at one of the second scanning pins 221. In this way, the detection module 23 will receive the corresponding analog voltage values ​​at different timings.

[0023] like Figure 1 As shown, in the first scanning module 21, one of the first scanning pins 211 corresponding to the upper left switch 141 outputs a high-level signal, and in the second scanning module 22, one of the second scanning pins 221 corresponding to the upper left switch 141 outputs a low-level signal, so that the upper left LED 143 is turned on under forward bias and begins to emit light (as shown by the two-dot chain), and so that one of the detection pins 231 corresponding to the upper left switch 141 in the detection module 23 receives the analog voltage value (as shown by the one-dot chain). At this time, the analog voltage value will be equal to the junction voltage of the upper left LED 143, that is, the minimum voltage required for the upper left LED 143 to turn on under forward bias. The analog voltage value will vary depending on the color of the LED 143, and the analog voltage value is not less than 1.5 volts and less than the voltage value of the high-level signal. At this time, the detection module 23 calculates an average threshold by averaging the default voltage value of the upper left LED 143 with the voltage value of the high-level signal. Then, the detection module 23 compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it means that the analog voltage value is closer to the default voltage value, indicating that the upper left switch 141 is pressed. Clearly, by receiving the analog voltage value in an analog reading manner, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0024] like Figure 2As shown, in the first scanning module 21, one of the first scanning pins 211 corresponding to the upper right switch 141 outputs a high-level signal, and in the second scanning module 22, one of the second scanning pins 221 corresponding to the upper right switch 141 outputs a low-level signal, so that the upper right light-emitting diode 143 is under forward bias and begins to conduct and emit light (as shown by the two-dot chain), and so that one of the detection pins 231 corresponding to the upper right switch 141 in the detection module 23 receives the analog voltage value (as shown by the one-dot chain). At this time, since the upper right switch 141 is not conducting, no current is generated between one of the detection pins 231 and one of the first scanning pins 211 corresponding to the upper right switch 141, so the analog voltage value will be equal to the high-level signal output by one of the first scanning pins 211 corresponding to the upper right switch 141, and the analog voltage value is equivalent to the voltage value of the high-level signal. At this time, the detection module 23 calculates another average threshold by averaging the default voltage value of the upper right LED 143 with the voltage value of the high-level signal. Then, the detection module 23 compares the analog voltage value with the average threshold. If the analog voltage value is greater than the average threshold, it means that the analog voltage value is closer to the voltage value of the high-level signal, indicating that the upper right switch 141 has not been pressed. Clearly, by receiving the analog voltage value in an analog reading manner, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0025] like Figure 3As shown, in the first scanning module 21, one of the first scanning pins 211 corresponding to the lower left switch 141 outputs a high-level signal, and in the second scanning module 22, one of the second scanning pins 221 corresponding to the lower left switch 141 outputs a low-level signal, so that the lower left LED 143 is turned on under forward bias and begins to emit light (as shown by the two-dot chain), and so that one of the detection pins 231 corresponding to the lower left switch 141 in the detection module 23 receives the analog voltage value (as shown by the one-dot chain). At this time, the analog voltage value will be equal to the junction voltage of the lower left LED 143, that is, the minimum voltage required for the lower left LED 143 to turn on under forward bias. The analog voltage value will vary depending on the color of the LED 143, and the analog voltage value is not less than 1.5 volts and less than the voltage value of the high-level signal. At this time, the detection module 23 calculates another average threshold by averaging the default voltage value of the LED 143 corresponding to the lower left with the voltage value of the high-level signal. Then, the detection module 23 compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it means that the analog voltage value is closer to the default voltage value, that is, it means that the switch 141 in the lower left is pressed. Obviously, by receiving the analog voltage value in an analog reading manner, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0026] like Figure 4As shown, in the first scanning module 21, one of the first scanning pins 211 corresponding to the lower right switch 141 outputs a high-level signal, and in the second scanning module 22, one of the second scanning pins 221 corresponding to the lower right switch 141 outputs a low-level signal, so that the lower right LED 143 is turned on under forward bias and begins to emit light (as shown by the two-dot chain), and so that one of the detection pins 231 corresponding to the lower right switch 141 in the detection module 23 receives the analog voltage value (as shown by the one-dot chain). At this time, the analog voltage value will be equal to the junction voltage of the lower right LED 143, that is, the minimum voltage required for the lower right LED 143 to turn on under forward bias. The analog voltage value will vary depending on the color of the LED 143, and the analog voltage value is not less than 1.5 volts and less than the voltage value of the high-level signal. At this time, the detection module 23 calculates another average threshold by averaging the default voltage value of the LED 143 corresponding to the lower right with the voltage value of the high-level signal. Then, the detection module 23 compares the analog voltage value with the average threshold. If the analog voltage value is less than the average threshold, it means that the analog voltage value is closer to the default voltage value, that is, it means that the switch 141 in the lower right is pressed. Obviously, by receiving the analog voltage value in an analog reading manner, the detection module 23 can more accurately determine the state represented by the analog voltage value.

[0027] It is worth mentioning that, during the research on anti-ghosting functionality, the applicant proposed a keyboard with anti-ghosting capabilities (as shown in Taiwan Patent Application No. 113112996), comprising a sensing unit, a detection unit, and a processing unit. The sensing unit includes multiple switch modules, each with multiple switches and multiple corresponding sensing resistors. The number of switches and sensing resistors is N. The resistance values ​​of the sensing resistors within each switch module form a sequence arranged in ascending order. Except for the first term, the value of any term in the sequence is greater than the sum of the values ​​of all preceding terms. The conduction state of the switches in each switch module causes each switch module to generate 2... NThe detection unit receives a voltage divider value corresponding to each of the equivalent resistance values. Finally, the processing unit determines the conduction status of the switching components based on the potential level value, generating a button signal indicating which of the switching components is pressed, thus achieving the anti-ghosting function. Based on the technical feature of receiving the voltage divider value, and in conjunction with the physical characteristics of the light-emitting diode, the applicant proposes to receive an analog voltage value of not less than 1.5 volts using an analog reading method, thereby achieving a more accurate anti-ghosting function and simultaneously achieving the light-emitting function.

[0028] In summary, this embodiment has the following advantages:

[0029] (i) The first scanning module 21 outputs the high-level signal sequentially at one of the first scanning pins 211, and the second scanning module 22 outputs the low-level signal sequentially at one of the second scanning pins 221. Then, the reverse cut-off characteristic of the light-emitting diode 143 in the switch module 14 is used to allow the detection module 23 to detect and receive the respective analog voltage values ​​according to different timing sequences, thereby determining the conduction status of the switch 141 and realizing the anti-ghost key function.

[0030] (ii) The first scanning module 21, the second scanning module 22, the current limiting resistor 142 and the light-emitting diode 143 work together to achieve the light-emitting function, and the power consumption generated by the current limiting resistor 142 is reduced by adjusting the voltage value of the high-level signal.

[0031] Therefore, the keyboard circuit of the present invention, which combines anti-ghosting and light-emitting functions, can indeed achieve the purpose of the present invention.

[0032] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A keyboard circuit that combines anti-ghosting and backlighting functions, characterized in that: The system includes a switching unit and a scanning unit. The switching unit comprises multiple main drive lines, multiple auxiliary drive lines, multiple sensing lines, and multiple switching modules. Each switching module has a switching element, a current-limiting resistor corresponding to its respective switching element, and a light-emitting diode (LED) electrically connected to its respective switching element and its respective current-limiting resistor. One end of each switching element is electrically connected to its respective sensing line, one end of each current-limiting resistor is electrically connected to its respective main drive line, the positive terminal of each LED is commonly electrically connected to the other end of its respective switching element and the other end of its respective current-limiting resistor, and the negative terminal of each LED is electrically connected to its respective auxiliary drive line. The scanning unit comprises 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 multiple first scanning pins respectively electrically connected to the main drive lines, the second scanning module has multiple second scanning pins respectively electrically connected to the auxiliary drive lines, and the detection module has multiple detection pins respectively electrically connected to the sensing lines. The detection module is used to receive analog voltage values ​​via its respective detection pins.

2. The keyboard circuit with both anti-ghosting and backlighting functions as described in claim 1, characterized in that: The first scanning module is used to output a high-level signal via one of the first scanning pins, and the second scanning module is used to output a low-level signal via one of the second scanning pins.

3. The keyboard circuit with both anti-ghosting and backlighting functions according to claim 2, characterized in that: The detection module is used to pre-store multiple default voltage values ​​indicating the junction voltage of the light-emitting diode, and after receiving the voltage value of the high-level signal from the first scanning module, the detection module is used to average the respective default voltage values ​​with the voltage value of the high-level signal to calculate an average threshold, and then compare the received analog voltage value with the average threshold to determine whether the respective switch is pressed.

4. The keyboard circuit with both anti-ghosting and backlighting functions according to claim 2, characterized in that: The voltage value of the high-level signal is not less than 3 volts and not more than 5.25 volts, and the voltage value of the low-level signal is not less than -0.1 volts and not more than 0.1 volts.

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