KR101749336B1

KR101749336B1 - Circuit and method for detecting phantom key in keyboard

Info

Publication number: KR101749336B1
Application number: KR1020150161952A
Authority: KR
Inventors: 이현창
Original assignee: 공주대학교 산학협력단
Priority date: 2015-11-18
Filing date: 2015-11-18
Publication date: 2017-07-03
Also published as: KR20170058131A

Abstract

The present invention relates to a method and apparatus for detecting a false key on a keyboard for detecting input of a phantom key or ghost key on a keyboard connected to a computer and controlling input of an accurate key. An apparatus for detecting a false key on a keyboard for achieving the object comprises an upper film, a lower film, and a plurality of rows and columns formed between the upper film and the lower film and recognizing contact between the upper film and the lower film A key matrix unit comprising a matrix of switches and applying a switch contact resistance to the underlayer film or the overlay film; A pull-up resistor to which one of the plurality of keys of the key matrix unit is connected and which has a corresponding number of resistors connected in parallel; And a microprocessor outputting a low to a corresponding column of the key matrix and receiving a voltage corresponding to the low output to determine whether the switch input is a normal key or a virtual key, The present invention has the effect of detecting an occurrence of a false key on a keyboard used by being connected to a computer and preventing the output from the false key from being applied, thereby controlling input of an accurate key.

Description

Technical Field [0001] The present invention relates to a virtual key detection apparatus and a method for detecting a virtual key on a keyboard,

The present invention relates to an apparatus and method for detecting a false key on a keyboard, and more particularly, to a method and apparatus for detecting a false key (phantom key or ghost key) on a keyboard connected to a computer, And more particularly, to a method and apparatus for detecting a false key on a keyboard.

Due to recent advances in semiconductor and computer technology, computers have become essential and essential devices for factory automation and office automation. This tendency has been widely spread in most households as well as in the personal-computer field used for personal use, and the spreading rate is getting faster due to the development of communication technologies such as the Internet. With the rapid spread of such computers, computer peripherals are also evolving, and in particular, a number of low cost and reliable devices have been produced by studying various technologies capable of mass production of keyboards and mice.

Computer keyboard is the most commonly used input device in general computer. It was a high-priced device of several hundred thousand won that produced individual push-switches assembled on a large number of boards in the days when the production amount of computer was not long. However, A membrane-type keyboard (also called an electronic keyboard) has been developed which is advantageous for mass production and at a lower cost. Membrane keyboards (electronic keyboards) occupy most of the keyboards currently used because they can produce high-performance computer keyboards in only a few thousand won, due to the simple structure of the hardware.

Membrane keyboards contribute to such low-cost and mass-production, but due to the difficulty of eliminating the phenomenon of phantom key due to the characteristics of the membrane keyboard, To overcome this problem, some users use expensive, individual switch-type keyboards (called "mechanical keyboards" in the market) that are configured in the past.

The virtual key phenomenon is a phenomenon in which three or more keys are pressed at the same time to detect a key that is not pressed by the user when a specific combination is made on the keyboard structure. In the case of a separate switch keyboard (mechanical keyboard) Although it is possible to recognize that each key is pressed at the same time, in the membrane type, it is difficult to prevent the false key phenomenon because the entire switch is constituted by one set of film and the switch wiring is also formed on the film and the attachment of the diode or the like is difficult.

Therefore, some keyboards may be configured to ignore two, three, or more keys in addition to the Shift, Ctrl, and Alt keys to prevent the user from detecting an incorrect key being pressed when more than three keys are pressed due to a typo, These are called 2-key rollover and 3-key rollover, respectively.

Membrane keyboards are not a problem at all, except for Shift, Ctrl, and Alt keys, which are rarely used to press more than two keys at the same time. However, in applications that press more than two at the same time, Problems arise because the simultaneous entry of key keys is not permitted or if a permissible key phenomenon occurs in a certain combination even if allowed. Examples of pressing multiple keys at the same time are computer games, keyboard-type switch inputs, and anatomy keyboard (three-key keyboard).

Especially, in a two-player game conducted through a computer, there are cases where eight keyboard keys are pressed at the same time. In this case, when the virtual key phenomenon occurs on the keyboard, the game often behaves erratically, unlike the user's will. For this reason, it is a reality that in a PC room and the like, half of the entire keyboard is provided with an expensive mechanical keyboard for a game user.

In the case of switchboards composed of keyboards such as electronic organs, virtual key phenomenon occurs because multiple keys are pressed at the same time, which results in the occurrence of an unusual tone. In addition, it is composed of the principle of inputting the combination of prefix, neutral and ending of Hangul at the same time, and it is easy to apply because of false key phenomenon in general keyboard. There is a problem that it can not be done.

In order to solve such a problem, Korean Patent Registration No. 10-0905283 (titled "keyboard capable of recognizing simultaneous input of multiple keys") discloses a method of using a diode in a membrane keyboard. The film used in general membrane keyboards is very thin at low cost and can not be soldered. In addition, since the diode needs to be connected in series with each switch contact point, the number of contacts (about 106 to 108) for the number of switches is formed There is a problem that the size of the contact portion becomes extremely large. This is because the substrate has to be larger as the number of parts increases and the number of contacts increases. For example, in the cited patent, the total number of the diode is 108 and the number of the soldering points is 216, the film size increases due to the increase of the contact size, the increase of the substrate size and the coating contact portion of the substrate contact portion also becomes at least 108 + 8, Is increased. Therefore, it is much smaller and less expensive to configure a static method and use a processor having a large number of ports, rather than configure it in the same manner as the cited invention.

FIG. 1 is a cross-sectional view illustrating a keyboard structure of a general membrane keyboard, and FIG. 2 is a perspective view illustrating a structure of a general membrane film according to FIG.

Referring to FIGS. 1 and 2, a membrane type keyboard is configured to easily install a large number of switches at a low cost and in a large amount. The key cap 10 located at the uppermost position in FIG. 1 is a portion where a character is engraved and pressed by the user. When the key cap is pressed, the silicone rubber 20 at the lower portion is resilient, and at the same time, 30).

Referring to FIG. 2, the membrane film 30 is a film having an upper layer film 32 and a lower layer film 36 printed with a conductive ink or carbon conductor facing the lower layer film 36, (Not shown). Therefore, when the upper layer film 32 is pressed by the silicone rubber 20, the contact of the upper layer film 32 contacts the lower layer film 36 to serve as a switch.

3 is a circuit diagram for detecting data by dynamic scanning in a general membrane type keyboard.

Referring to FIG. 3, a dynamic scanning circuit that detects a large number of switch states is used as a port of a limited microcontroller. L (low) 'output in the order of Y1, Y2 and Y3 through the output port and open-collector buffers U1, U2 and U3 to detect the state of all the switches, and if SW22 is pressed Since X2 of the input port is detected as 'L' when Y2 is 'L', it is possible to detect that the switch SW22 is pressed. In this manner, 64 switches can be detected when X is 8 rows and Y is 8 columns, and 128 switches can be detected when Y is 16 columns. Open-collector buffers in the circuit ensure that the outputs of the gates do not collide, for example, when two or more switches are pressed horizontally simultaneously, such as SW31 and SW32.

However, in the dynamic scanning method described with reference to FIG. 3, a large number of switches can be sequentially detected using a small amount of processor ports. However, when the switches at specific positions are pressed together by this structural feature, This phenomenon is called a phantom key phenomenon.

4 is a configuration diagram of a simple switch circuit for explaining a virtual key generated in a keyboard in general.

4, the point marked dark in FIG. 4 is a place where the switch is pressed. When the processor sets this line to 'L' to check the Y1 column, X1 and X2 are both 'L' by SW11 and SW21, . However, if it is set to 'L' to inspect the Y2 column, the X1 line becomes 'L' by the SW12, but the X2 line where the switch is not pressed is also changed to 'L' through the SW21, SW11 and SW12, Is detected as being pressed. That is, the false key phenomenon occurs when the switch array becomes a square.

5 is a block diagram of a circuit for explaining generation of a virtual key in a keyboard according to another embodiment. As shown in FIG. 5 (a), SW 12 and SW 23 become virtual keys when the switches are pressed as shown in FIG. 5 (b) in the horizontal and vertical 3 X 2 array. When switches are pressed as shown in the figure, SW22 and SW32 become virtual keys.

6 is a circuit diagram showing a configuration of a circuit for removing a false key generally generated on a keyboard.

Referring to FIG. 6, as shown in FIG. 6, a diode may be attached in series to each switch to remove a false key phenomenon. When scanning a row in which the switch is located, current is passed through. However, when scanning another row (Y2 in the figure), the current flowing through the other switches SW11 is blocked (Y2) to prevent the SW22 from becoming a false key.

However, the method of FIG. 6 described above is applicable only to a keyboard (mechanical keyboard) composed of individual switches as described above, and it is difficult to apply a diode to a film in a membrane type keyboard.

Another method is to use a static method of directly connecting the port of the processor to each switch without detecting the switches by the dynamic scanning method. This is advantageous in that the virtual key phenomenon does not occur fundamentally, The number of ports of the processor must be increased to 100. Therefore, the complexity of the device is greatly increased, and thus it is limited in applications such as a key keyboard in which false key phenomenon should never occur.

Since this method can be applied to both individual switch type and membrane type, some gaming keyboards use n-key rollover, but there are problems in the number of processor ports and the number of contacts So that the price is significantly increased as compared with a general membrane type keyboard.

Therefore, in order to prevent false key phenomenon on the current membrane type keyboard, it is necessary to use a suitable switch combination in which the square arrangement is not formed in the keyboard switch matrix. However, since the matrix configuration is different for each keyboard maker and the user uses all the switch combinations, Depending on what kind of game you are playing with the keyboard of the keyboard, the key generation may be relatively less or more severe. However, in any case, the generation of the false key can not be avoided in the membrane type keyboard, and the user has to use such inconvenience. In addition, due to such a problem, the Internet has created and exchanged virtual key list information for each maker among the users, and selects the keyboard.

Korean Patent No. 10-0905283 entitled " Keyboard capable of recognizing simultaneous input of multiple keys "

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a keyboard and a method for detecting a false key generated on a keyboard connected to a computer, And to provide a virtual key detection method and a detection device on a keyboard that can control input.

To achieve the above object, a virtual key detecting apparatus in a keyboard includes an upper film, a lower film, and a plurality of rows and columns formed between the upper film and the lower film and recognizing contact between the upper film and the lower film. A key matrix unit comprising a matrix of switches to be formed and applying a switch contact resistance to the lower layer film or the upper layer film as necessary;

A pull-up resistor to which one is connected corresponding to one row constituted by a plurality of keys of the key matrix unit and in which a number of resistors corresponding to the row of the key matrix are connected in parallel; And

And a microprocessor outputting a low to a corresponding column of the key matrix and receiving a voltage corresponding to the low output and determining whether the switch input is a normal key or a virtual key, do.

The voltage generated by the normal key (

)silver,

Respectively,

The voltage generated by the virtual key

)silver,

Respectively,

The difference between the voltage generated by the virtual key and the voltage generated by the normal key can be obtained by the following equation.

(here,

Up resistor,

Is a switch contact resistance,

Indicates an applied voltage applied to the keyboard)

Pull-up resistor

) And the switch contact resistance (

) Can be configured to have the following ratios.

The pull-up resistor

) Is set within the range of 1.2 K Ω to 3.9 K Ω, and correspondingly, the switch contact resistance (

) Can be configured within a range of 1.4697 K ? To 4.7765 K ?.

The microprocessor generates a determination reference voltage for distinguishing the virtual key from the normal key

) Is obtained by the following equation,

If the key matrix, if a voltage input from the key through the portion higher than the voltage at the 3.663 V determination key virtual image, and is lower than the voltage at the 3.663 V may be configured to determine the normal keys.

To accomplish the above object, a virtual key detection method and detection apparatus in a keyboard includes: initializing a keyboard; Outputting a row to a column counter of a keyboard switch; Initializing a row counter of a keyboard switch; A processing step of processing the key; Performing dynamic scanning on the next row of the keyboard switch; Scanning the next row when the dynamic scanning of one row of the keyboard switch is terminated; And returning to initializing the column counter when scanning for the entire column is completed.

The processing step includes a state-0 in which the current key is not pressed, and the state remains in this state when it is detected that the continuation key is not pressed; If it is detected that the key is pressed, the state is reserved to communicate that the key is pressed, and the state is performed after state-0, and the chattering that occurs after the key is pressed is removed. ; It is performed after the state-1 and the key is pressed. If the key is continuously pressed, the state staying in this state is counted, and when it is continuously pressed, the state is auto-repeat-2. And state-3, which is performed after the state-2 and counts the chattering removal time after the chattering which occurs after the key is turned off, and proceeds to the state-0 when the count is ended .

Extracting a flag of the corresponding key of the keyboard corresponding to the current matrix, and A / D-converting the signal generated in the corresponding row if the flag is in the state-0; Determining whether the A / D converted signal is lower than a reference voltage; Terminating the key processing if it is determined that the A / D converted signal exceeds the reference voltage; If it is determined that the A / D converted signal is lower than the reference voltage, initializing the chattering counter by setting the flag to '1'; And storing the information indicating that the key is pressed in a communication buffer.

Extracting a flag of a corresponding key of a keyboard corresponding to a current matrix, and A / D-converting a signal generated in the corresponding row if the flag is in a state-2; Determining whether the A / D converted signal is lower than a reference voltage; Terminating the key process if it is determined that the A / D converted signal is lower than the reference voltage; Setting the flag to '3' and initializing the chattering counter if it is determined that the A / D converted signal exceeds the reference voltage; And storing information indicating that the key is turned off in the communication buffer.

Therefore, the false key detection method and detection apparatus in the keyboard of the present invention can detect an occurrence of a false key on a keyboard connected to a computer and prevent the output from the false key from being applied, It is effective.

Further, the false key detection method and detection apparatus in the keyboard of the present invention can be applied to a separate switch system (mechanical keyboard) for preventing the false key by using a diode. In this case, since a resistance element is used instead of a diode, There is an effect that the risk of high-frequency malfunction of the diode due to dynamic scanning is eliminated.

In addition, the virtual key detection method and detection apparatus of the present invention can distinguish a virtual key from a normal key even in a combination of many keys according to the detection performance of the processor, There is an effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a keyboard structure in a general membrane type keyboard. FIG.
FIG. 2 is a perspective view showing a structure of a general membrane film according to FIG. 1. FIG.
3 is a circuit diagram for detecting data by dynamic scanning in a general membrane keyboard.
4 is a block diagram of a simple switch circuit for explaining a virtual key generated in a keyboard in general.
5 is a configuration diagram of a circuit for explaining generation of a false key in a keyboard according to another embodiment;
6 is a circuit diagram showing a configuration of a circuit for removing a false key generally generated on a keyboard.
FIG. 7 is a perspective view illustrating a structure of a membrane for detecting a false key in a keyboard according to an embodiment of the present invention; FIG.
FIG. 8 is a circuit diagram showing the configuration of the membrane of FIG. 7 according to an embodiment of the present invention;
9 is a circuit diagram showing an equivalent circuit of the membrane of FIG. 8 according to one embodiment of the present invention.
10 is a graph showing a voltage difference according to a resistance ratio according to an embodiment of the present invention.
11 is a circuit diagram of a switch assuming that eight keys are simultaneously pressed according to another embodiment of the present invention.
Figure 12 is an equivalent circuit diagram of an arrangement of 4 x 2 horizontally and vertically in Figure 11 according to another embodiment of the present invention;
13 is an exemplary view showing an example of a key combination in a key membrane part according to an embodiment of the present invention;
FIG. 14 is a table showing the voltages of the normal key and the false key corresponding to the key combinations in FIG. 13 according to an embodiment of the present invention, and the voltage difference therebetween. FIG.
FIG. 15 is a graph showing the voltages of the normal key and the false key according to the key combination of FIG. 13 according to an embodiment of the present invention, and the voltage difference therebetween. FIG.
Figure 16 is a block diagram of an embodiment of the present invention

Wow

And the minimum current corresponding thereto.
17 is a matrix structure diagram showing an example of a circuit configuration for detecting a false key on a keyboard according to an embodiment of the present invention;
FIG. 18 is a diagram for explaining a state of processing an n-key rollover in a keyboard according to an embodiment of the present invention; FIG.
FIG. 19 is a flowchart showing a step of controlling a keyboard according to an embodiment of the present invention; FIG.
20 is a diagram illustrating an on-off switch status flag in a keyboard according to an embodiment of the present invention;
21 is a state diagram illustrating processing of an on-off switch state flag in a keyboard according to an embodiment of the present invention;
22 is a flowchart illustrating in greater detail the processing of the key of FIG. 21 according to one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings showing embodiments of the present invention. 7 is a perspective view illustrating a structure of a membrane for detecting a false key in a keyboard according to an embodiment of the present invention.

Referring to FIG. 7, the film constituting the switch of the membrane keyboard is formed by applying conductive ink or carbon conductor. The conductors used at this time have been improved so as to reduce the net resistance in order to improve the performance of the switch. The smaller the net resistance, the higher the price. However, in the present invention, the upper layer film 32 and the spacer film 34 are formed in the same manner, and a low-cost high-resistance conductor is once applied to a portion corresponding to the spacer on the upper portion of the lower layer film 310, And it can be applied to the contact portion of the upper layer film 32 as occasion demands. An equivalent circuit in the case where the film is constituted by the high-resistance contact is shown in Fig.

FIG. 8 is a circuit diagram showing the configuration of the membrane of FIG. 7 according to an embodiment of the present invention, and FIG. 9 is a circuit diagram showing an equivalent circuit of the membrane of FIG. 8 according to an embodiment of the present invention.

Referring to Figures 8 and 9,

,

Is a resistance component formed at the membrane switch contact point,

,

Are pull-up resistors for detecting the state of the switch. If SW11, SW12 and SW21 are turned on and SW22 is turned off to operate as a false key, scanning the Y1 column in a normal state results in an equivalent circuit as shown in Fig. 9 (a)

,

) Are detected in the same manner. However, when the Y2 column in which the false key is generated is scanned, an equivalent circuit as shown in FIG. 9 (b) is constituted so that the voltage

And voltage by false key

And the microprocessor compares the value of each key through the analog / digital conversion of the voltage to determine whether the false key or the normal key is detected.

Normal voltage

And voltage by false key

The largest difference between

Wow

The step of determining the resistance ratio of the resistor is as follows. First, in the equivalent circuit shown in Figs. 9 (a) and 9 (b), all

Are the same,

&Lt; / RTI >

Lt; / RTI >

Are the same,

&Lt; / RTI >

. According to this theorem

Can be obtained from the following Equation 1

Can be obtained from the following equation (2).

From equations (1) and (2)

Wow

Can be expressed by Equation (3).

10 is a graph showing a voltage difference according to a resistance ratio according to an embodiment of the present invention.

Referring to FIG. 10, using Equation 3 described above

Switch contact resistance (

And a pull-up resistance.

), There is a point where the voltage difference is maximum as shown in FIG.

When the two voltage differences are maximum

Wow

To obtain the relationship,

And is set to 0, the following equation (4) can be derived.

Since the numerator part in Equation (4) should be 0, Equation (5) can be obtained by expressing the Equation (5) again.

The following equation (6) can be obtained by summarizing the equation (5).

In order to check the voltage difference generated in the switch of the keyboard, Equation (6) is substituted into Equation (3) and the following Equation (7) can be obtained.

That is, in a state where the condition of Equation (6) is satisfied, a voltage

Ramen

Regardless of the value, between the normal key voltage and the virtual key voltage

A voltage difference between the first and second electrodes is generated.

By the condition of Equation (6)

and

The following equations (8) and (9) can be obtained by substituting Equation (6) into Equations (1) and (2), respectively.

In other words,

In case of a transistor-transistor logic (TTL) voltage,

Into Equation 7,

Can obtain a value of 1.465 V ,

Are substituted into Equations (8) and (9), respectively,

And

Can be obtained. here

Represents a normal key value,

Represents a virtual key value.

On the other hand, in the case of a two-player game, one person may press up to eight arrow keys simultaneously, two arrow keys, two attack keys, and up to eight arrow keys simultaneously. Typically, even six to eight keyboards are pressed simultaneously.

11 is a circuit diagram of a switch assuming that eight keys are simultaneously pressed according to another embodiment of the present invention. As shown in FIG. 11, when the eight keys are all pressed in the same square, the key is not pressed because the entire key is normally pressed. However, in FIG. 11, when seven keys are pressed in a square and one is in a false key, the smallest detection voltage difference occurs between the false key and the normally pressed switch.

11, there may be a case of an arrangement of 2 x 4 in the horizontal and vertical directions and an arrangement of 3 x 3 in the horizontal and vertical directions in addition to the horizontal and vertical 4 x 2 arrangements. However, as shown in the simulation results to be described later, Fig. 12 shows an equivalent circuit when Y2 is scanned in this circuit.

Fig. 12 is an equivalent circuit of the arrangement of 4 x 2 horizontally and vertically in Fig. 11 according to another embodiment of the present invention.

Referring to FIG. 12, for the analysis of the circuit,

Are the same,

&Lt; / RTI >

Lt; / RTI >

Are the same,

&Lt; / RTI >

. According to this definition

and

Can be expressed by the following equations (10) and (11), respectively.

With reference to equations (10) and (11)

from

Can be expressed by the following equation (12). &Quot; (12) "

With respect to Equation (12)

And the numerator is set to 0, the following equation (13) can be obtained.

Substituting the result of Equation (13) into Equation (12), the following Equation (14) can be obtained.

The voltage applied to a general TTL circuit is

If

, And the output corresponding to the normal key is

And the output corresponding to the false key is

. The voltage difference of 0.775 V obtained from the result of Equation (14)

Since it corresponds to 15.5% of the voltage, even if the device error is considered, the microprocessor can sufficiently distinguish it.

Therefore, the determination reference voltage for distinguishing the virtual key from the normal key

Can be obtained by the following equation (15).

In order to examine whether the conditions regarding the key combinations of the 4 x 2 array obtained in the above manner can be applied to other key combinations, the case where the resistance ratio of the expression (13) is the key of the array of 2 x 2 Results calculated by

Was obtained. In case of normal key

, And when the key is a virtual key

Was obtained. Therefore, the determination reference voltage (< RTI ID = 0.0 >

), It can be understood that the normal key and the virtual key can be distinguished from the arrangement of 2 x 2 in the horizontal and vertical directions and the key arrangement in the other array.

13 is an exemplary view showing an example of a key combination in a membrane part according to an embodiment of the present invention. 13 (a) shows a layout of 2 x 2 in height and width. Fig. 13 (b) shows a layout of 3 x 2 horizontal and vertical keys. 13 (c) shows an arrangement of 4 x 2 horizontally and vertically. Fig. 13 (d) shows an arrangement of 2x3 horizontal and vertical keys. FIG. 13 (e) shows an arrangement of 2x4 horizontal and vertical keys. Fig. 13 (f) shows an arrangement of 3x3 horizontal and vertical keys.

FIG. 14 is a table showing the voltages of the normal key and the false key corresponding to the key combinations in FIG. 13 according to an embodiment of the present invention, and the voltage difference therebetween.

Referring to FIG. 14, it can be seen that the combination of the horizontal and vertical 4 X 2 key arrangements has the lowest voltage difference. Despite applying the most favorable resistance ratio to the combination of 4 x 2 key arrangement, this combination has the smallest voltage difference compared to the other combinations, so the resulting decision reference voltage

) Means that other arrays can be accommodated. Therefore, if the boundary voltage of Equation (15) according to the arrangement of the horizontal and vertical 4 X 2 keys is applied to the entire keyboard, the false key and the normal key can be distinguished from each other in the combination of all keys.

FIG. 15 is a graph showing the voltages of the normal key and the false key according to the key combination of FIG. 13 according to an embodiment of the present invention, and the voltage difference therebetween.

Referring to FIG. 15, a method for detecting a virtual key on a membrane keyboard is presented. A hardware change is applied to the membrane film, and the optimum determination reference voltage (

), It is possible to distinguish between a virtual key and a normal key for all combinations of keys. That is, as in the above-described embodiment, the optimum resistance ratio corresponds to a combination of the horizontal and vertical 4 X 2 key arrangements having the smallest detection voltage difference

, And it is confirmed that the false key can be detected by applying this ratio (judgment reference voltage) to other key combinations by simulation.

FIG. 16 is a graph

Wow

And the minimum current corresponding thereto.

Referring to FIG. 16, if a pull-up resistance

) Is applied to the paint resistance, a special resistance value is generated, and the unit cost can be greatly increased because the resistance must be customized. Therefore, depending on the conductive paint to be applied to the membrane film, the switch contact resistance

). That is, a pull-up resistor (

) Is first determined as a commercial resistance value, and then paint resistance is determined according to the table of FIG. 16, which is more efficient and can be implemented at a low cost.

16 shows the pull-up resistor in the leftmost row, the resistance in the next column is the resistance of the switch contact determined by the paint resistance according to Equation (13), the next row is the composite resistance in series connection of the two resistors, Represents the current that flows when a +5 V voltage is applied to this composite resistor. In the table of FIG. 16, since the minimum current is a current flowing when one key is pressed, the current written in FIG. 16 can be referred to as the minimum current because the current is larger than the current when two or more are pressed.

If this current is large, stability against noise of the keyboard is improved. However, excessive current may increase the consumption current, the wiring of the membrane film may be burned out. In particular, since there is a basic resistance in the film wiring, There is a problem that a voltage is generated and influenced.

Further, when the resistance value becomes larger, the current becomes smaller, and the influence of the wiring resistance of the membrane film can be neglected. However, if the current is too small, the signal becomes weak and the keyboard becomes vulnerable to noise and the likelihood of malfunction increases. Therefore, it is necessary to select a combination which can pass a proper current for stable operation while ignoring the wiring resistance of the membrane film. Generally, about 0.5 mA - 2 mA is sufficient, so set the pull-up resistor and switch resistor value so that the resistor ratio within this range can be selected. In other words,

Is set within the range of 1.2 K ? To 3.9 K ? And correspondingly

Is set within the range of 1.4697 K ? To 4.7765 K ?. Preferably, the pull-up resistor is designed to have a ratio of 1.8 K ? (1800?) To 2.2 K ? (2200?) As shown in the table of FIG.

17 is a matrix structure diagram showing an example of a circuit configuration for detecting a false key on a keyboard according to an embodiment of the present invention.

Referring to FIG. 17, the configuration of the present invention can be divided into a microprocessor 100, a pullup resistor unit 200, and a key matrix unit 300.

In Fig. 17, the pull-up resistor unit 200 includes a total of eight pull-up resistors (

) Is used, and a pull-up resistor (

Uses a resistor having the same capacitance as described with reference to Fig.

Up resistor of the pull-up resistor unit 200 (

Are connected to the analog-to-digital conversion input of the microprocessor 100. The analog- For example, a processor such as ATmega 8535 ( ^TM) or ATmega165 ( ^TM ) of Atmel having an 8-channel A / D (Analog-to-Digital) conversion circuit built in the microprocessor 100 can be used.

The key matrix portion 300 is composed of an upper layer film, a lower layer film, and a matrix of a plurality of switches formed between the upper layer film and the lower layer film and recognizing contact between the upper layer film and the lower layer film. Further, as described above, the lower layer film 310 or the upper layer film 32, if necessary,

). As described above,

Is configured to have a resistance value higher than that of a commonly used switch so that the difference between the voltage generated by the normal key and the voltage generated by the false key is distinguished.

The lines of 16 bits written as Port0 and Port1 of the microprocessor 100 select a row of the key matrix unit 300 and pass through an open-collector gate at this time, (0) when the pin is 'H (high)' and '0' when it is 'L (low)', the floating and 0 V states are displayed. . The microprocessor 100 processes signals from the key matrix unit 300 composed of 16 rows and 8 rows and 8 rows. That is, the microprocessor 100 can detect the signals of the respective switches (keys) to which the terminals of a total of 128 key matrix units 300 are connected. This is because the keys (108 to 104) It is possible to detect all of the signals of the mobile station.

The signal detected by the microprocessor 100 distinguishes the difference in voltage generated by the normal key and the false key. The microprocessor 100 compares the false key and the normal key with a determination reference voltage ("

). If the key is a virtual key, do not allow key input.

18 is a diagram for explaining a state of processing an n-key rollover in a keyboard according to an embodiment of the present invention. Since the keyboard according to the present invention needs to handle all eight keys simultaneously, if necessary, all keys must be simultaneously detected and processed in real time. That is, as shown in FIG. 18, when the 'A' key and the 'B' key are pressed at the same time, the chattering removal processing for the 'A' key and the 'B' key must be performed at the same time. Even if the key is pressed, processing for the 'C' key must be started. If the previously pressed 'D' key is off during this step, the off process is also performed simultaneously. Therefore, if the keyboard control program processes only one key of the event, and then processes the other key, the n-key rollover is not performed and the processing of all the keys must be performed together as a whole.

FIG. 19 is a flowchart showing a step of controlling a keyboard according to an embodiment of the present invention. The microprocessor 100 processes the processing in a step to be described later.

Referring to FIG. 19, power is input to the keyboard in step S202. For example, when a main body apparatus such as a personal computer (PC) or a notebook computer is turned on, power is also applied to the keyboard. Or directly powered by a separately manufactured keyboard.

In step S204, the keyboard is initialized. The initialization of the keyboard initializes the cache variables, resets the watch-dog timer, and initializes the I / O port settings and the like.

In step S206, a column counter of the keyboard switch is initialized. The switches on the keyboard can be configured in the form of an 8 x 16 matrix.

And outputs a low to a corresponding column of the keyboard switch initialized in step S208. For example, an output of 'L (low)' is sent to one column selected from the sixteen columns in FIG.

In step S210, a row counter of the keyboard switch is initialized.

The corresponding key is processed in step S212. The process of processing the key will be described in more detail with reference to the following drawings.

In step S214, the row counter of the keyboard switch is decreased by '1'.

In step S216, it is determined whether or not the dynamic scanning of one row of the keyboard switch has been completed.

If it is determined that the dynamic scanning of one column of the keyboard switch is terminated (Y in step S216), the column counter of the keyboard switch is decreased by '1' (step S218). If it is determined that the dynamic scanning of one column of the keyboard switch is not ended (N in step S216), the process returns to step S212, which is a step of processing the key.

It is determined in step S220 whether or not the dynamic scanning of the entire keyboard switch has been completed.

If it is determined that the dynamic scanning of all the rows of the keyboard switches has been terminated (Y in step S220), the process returns to step S206. If it is determined that the dynamic scanning of all the rows of the keyboard switches is not terminated (step S220) Return.

When an interrupt such as a power-off is input while the scanning of all the switches of the keyboard is repeatedly performed, the dynamic scanning is terminated. Accordingly, all the keys of the keyboard are always scanned by this processing procedure, and processing of the state of the keyboard is continuously performed.

20 is a diagram illustrating an on-off switch state flag in a keyboard according to an embodiment of the present invention, and FIG. 21 is a state diagram illustrating processing of an on-off switch state flag in a keyboard according to an embodiment of the present invention .

In FIG. 20, the state of the switch is largely divided into an on state and an off state, and the chattering counter operates before and after the switch is turned on to remove noise. Therefore, the switch can be classified into a state of a key-off state-0, a state of a warm-tering state-1, an on-state-2 state, and an off-chattering state-3.

As shown in FIG. 21, each key of the keyboard is periodically checked once, and switch state flag variables are assigned to each key as shown in FIG. 20 in order to maintain state information on the state of the key at that time. Each key also assigns one chattering counter variable to count the chattering time.

State-0 is the state in which the current key is not pressed and remains in this state if it is detected that the key has not been pressed continuously, and proceeds to state-1, reserving to communicate that the key is pressed if the key is detected to be pressed.

State-1 is a state that eliminates chattering that occurs after a key is pressed, counting the chattering removal time (typically about 20 mS ). If the count has not yet been completed, it remains in this state, and if the count is terminated, proceed to state -2.

State-2 is a state where the key is pressed, and remains in this state when the key is continuously pressed. At this time, it is possible to count the time remaining and perform an auto-repeat function. If it is detected that the key is off, proceed to state-3 while reserving to communicate that the key is off.

State-3 is a state of eliminating chattering occurring after the key is turned off, counting the chattering removal time (typically about 20 mS ). If the count has not yet been completed, it remains in this state, and if the count has ended, go to state-0.

FIG. 22 is a flowchart illustrating in more detail the processing of the key of FIG. 21 according to an embodiment of the present invention.

Referring to Fig. 22, the microprocessor 100 processes the processing in a later-described step.

The flag of the corresponding key of the keyboard corresponding to the current matrix is extracted in step S302.

And branches according to the state of the flag of the corresponding key of the keyboard extracted in step S304. The flag state of the key is divided into four as shown in FIG. 20 and FIG.

First, if the state of the key of the keyboard extracted in operation 304 is the state-0 in which the current key is not pressed, the signal generated in the corresponding line is A / D converted (operation S306).

It is determined in step S308 whether the A / D-converted signal is equal to or lower than the reference voltage.

If it is determined that the A / D converted signal exceeds the reference voltage (step S308, N), the key process is terminated.

If it is determined that the A / D converted signal is equal to or lower than the reference voltage (Y in step S308), the flag is set to '1' to initialize the chattering counter (step S310).

In step S312, information indicating that the key is pressed is stored in the communication buffer.

Next, if the state of the key of the keyboard extracted in step S304 is the state-1 in which chattering caused by the pressing of the key is eliminated, the chattering counter is decreased by '1' (step S314)

In step S316, it is determined whether or not the chattering counter is '0'.

If it is determined that the chattering counter is not '0' (step S316, N), the key process is terminated. If it is determined that the chattering counter is '0' (step S316, Y), the flag is set to '2' (step S318) and the key process is terminated.

Next, if the state of the key of the extracted keyboard is the state -2 in which the key is pressed, the signal generated in the corresponding row is A / D converted (step S320).

It is determined in step S322 whether the A / D-converted signal is equal to or lower than the reference voltage.

If it is determined that the A / D converted signal is equal to or lower than the reference voltage (Y in step S322), the key process is terminated.

If it is determined that the A / D converted signal exceeds the reference voltage (step S322, Y), the flag is set to '3' and the chattering counter is initialized (step S324)

In step S326, information indicating that the key is off is stored in a communication buffer provided in the microprocessor 100 and configured as a transmission / reception buffer.

Next, if the state of the key of the keyboard extracted in step S304 is state-3, which eliminates chattering occurring after the key is turned off, the chattering counter is decreased by '1' (step S328)

In step S330, it is determined whether or not the chattering counter is '0'.

If it is determined that the chattering counter is not '0' (NO in step S330), the key process is terminated. If it is determined that the chattering counter is '0' (step S330, Y), the flag is set to '0' (step S332), and the key process is terminated.

In the present invention, as in other keyboards, the status of a key is not digitally detected at a time in eight columns, but is detected by performing one-key analog-to-digital conversion in one column. Therefore, it is necessary to consider this.

Typically, the AVR processor has a built-in 10-bit analog-to-digital converter that takes 25 cycles to convert a single channel, including sample and hold times. This corresponds to 50 clocks for the processor system clock. If the processing is performed automatically at the correct timing by using the analog / digital conversion interrupt, the processing of the previous conversion value is performed simultaneously during the analog / digital conversion, It takes 50 clocks to process. Therefore, the time required to process one column can be calculated as one column processing time = (one key processing time: 50 clocks) X (8 keys) = 400 clocks. Since there are 16 such columns, the key scan time = (one column processing time: 400 clocks) X (16 columns) = 6,400 clocks can be calculated.

Even if the other processing times such as the communication processing during a single scan are up to 600 clocks, it takes about 7,000 clocks per scan. This is enough time to detect all of the keys, including chattering of the keys, which can scan the entire key once in 1.5 mS (571 times per second), even if the processor is running at a low speed of 4 MHz .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. will be. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Microprocessor 200: Pullup resistor unit
300: key matrix part

Claims

A virtual key detection apparatus in a keyboard, comprising: an upper layer film, a lower layer film, and a matrix of switches constituted between the upper layer film and the lower layer film and composed of a plurality of rows and columns which recognize contact between the upper layer film and the lower layer film A key matrix unit configured to apply a switch contact resistance to the lower layer film or the upper layer film;
A pull-up resistor to which one is connected corresponding to one row constituted by a plurality of keys of the key matrix unit and in which a number of resistors corresponding to the row of the key matrix are connected in parallel; And
And a microprocessor for outputting a low to a corresponding column of the key matrix and receiving a voltage corresponding to the low output to determine whether the switch input is a normal key or a virtual key,
The voltage generated by the normal key (

)silver,

Respectively,
The voltage generated by the virtual key

)silver,

Respectively,
Wherein a difference between a voltage generated by the false key and a voltage generated by the normal key is obtained by the following equation.

(here,

Up resistor,

Is a switch contact resistance,

Indicates an applied voltage applied to the keyboard)

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2. The method of claim 1, wherein the pullup resistor (

) And the switch contact resistance (

)silver,
And the second key is configured to have the following ratio.

The method of claim 1, wherein the pull-up resistor (

)silver,
It is set within the range of 1.2 K Ω to 3.9 K Ω and corresponds to the switch contact resistance (

) Is configured within a range of 1.4697 K ? To 4.7765 K ?.

2. The microprocessor according to claim 1,
A determination reference voltage for distinguishing the virtual key from the normal key

) Is obtained by the following equation,

The key matrix when the voltage input from the key through the portion higher than the voltage at the 3.663 V determination key virtual image and virtual image of the key is detected on the keyboard is configured to determine if a key top is lower than the voltage at the 3.663 V device.

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