CN101473543A - Two-wire connection to a key matrix in a mobile device - Google Patents
Two-wire connection to a key matrix in a mobile device Download PDFInfo
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- CN101473543A CN101473543A CNA2007800224072A CN200780022407A CN101473543A CN 101473543 A CN101473543 A CN 101473543A CN A2007800224072 A CNA2007800224072 A CN A2007800224072A CN 200780022407 A CN200780022407 A CN 200780022407A CN 101473543 A CN101473543 A CN 101473543A
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Abstract
A first current is driven through a first current path from a first common node, through a key matrix, and to a second common node when a key is pressed. A first measurement of the first current path resistance is made. A second current is then driven through a second current path from the second common node, through the key matrix, and to the first common node. A second measurement of the second current path resistance is made. The first and second measurements are used to identify the key that was pressed. Each key corresponds to a unique pair of first and second measurement values. In one example, non-linear resistance circuits are disposed at the ends of the row and column conductors of the key matrix such that a row resistor in the first current path is measured independently of a column resistor in the second current path.
Description
The cross reference of related application
The application's case is according to the rights and interests of the 60/815th, No. 297 provisional application case of 35 U.S.C. §, 119 opinions application on June 20th, 2006, and described provisional application case is incorporated herein by reference.
Technical field
The embodiment that is disclosed relates to key scan, and more particularly, relates to the key scan of the key-press matrix with a large amount of buttons.
Background technology
Cellular phone has the user and can press to use and to control the button of phone.Need a circuit to determine which button of user in having pushed button.Fig. 1 (prior art) is the sketch of conventional cellular phone key scanning circuit.Described circuit comprises baseband processor integrated circuit 1 and key-press matrix 2.Key-press matrix 2 comprises a plurality of horizontally extending column conductor 3-6 and a plurality of vertically extending row conductor 7-10.Button is associated with each crosspoint of column conductor and row conductor.If the user pushes button, then Dui Ying column conductor is coupled to corresponding row conductor.In operation, whether the key scanning circuit of baseband processor 1 scanning is passed column conductor, is driven into signal among the described column conductor 3-6 each one by one and detected described signal and be present among the row conductor 7-10 any one.For instance, if supress button 11, then when baseband processor 1 drives column conductor 4, its will be on row conductor 8 detection signal.Which button in the described button is supressed in the row conductor indication that signal is driven to the column conductor on it and detects signal thereon.For the cost reason, need to reduce the number of the terminal on the base band integrated circuit 1.Therefore need to reduce the number that is connected between baseband processor and the key-press matrix.
Fig. 2 (prior art) is the sketch of another conventional cellular telephone circuit.Dedicated button scanning monitor integrated circuit 12 is carried out pushed button which button in the button of matrix 13 of key scan functions and sensing.Key scan controller 12 then 14 will be forwarded to baseband processor integrated circuit 15 about the information of supressing which button via being connected in series.Owing to the serial interface between baseband processor integrated circuit 15 and the key scan controller 12, to compare with the circuit of Fig. 1, the number of the terminal on the baseband processor integrated circuit 15 is reduced.Yet shortcoming is that key scan controller IC 12 is another integrated circuits that must provide in cellular phone.Provide described extra integrated circuit (it typically is microprocessor or dedicated button scan state machine) to add unacceptable and not low cost to cellular phone.
Fig. 3 (prior art) is the sketch of another conventional cellular telephone circuit.Independent discrete resistor is placed between each conductor among the column conductor 17-20 of first common node 16 and key-press matrix 21.These independent discrete resistor are represented with reference number 22-25 in Fig. 3.Similarly, independent discrete resistor is placed between each conductor among the row conductor 27-30 of second common node 26 and described key-press matrix.These resistors are represented with reference number 31-34 in Fig. 3.Low-power resistance in the baseband processor 35 changes testing circuit and monitors described matrix at the change of the resistance between first common node and second common node.If detect the change of resistance, then described low-power resistance changes testing circuit and enables more accurate sensing circuit.Described more accurate sensing circuit is measured the SENSE+ terminal of baseband processor integrated circuit 35 and the resistance between the SENSE-terminal.Each button causes the unique resistance between SENSE+ terminal and the SENSE-terminal when being pressed.Therefore, use the resistance of measuring by described accurate sensing circuit to discern the button that is pressed.For instance, if button 36 is pressed, then column conductor 18 is coupled to row conductor 28, makes the total series resistance that has 5R between the SENSE+ of baseband processor integrated circuit 35 terminal and SENSE-terminal.
Fig. 4 (prior art) is the form at the resistance of each possible button that can be pressed between the SENSE+ terminal of showing base band integrated circuit 35 and the SENSE-terminal.Mind you, 5R resistance are unique and discern the button that is pressed to be " 5 " button 36.
The shortcoming of the circuit of Fig. 3 is that the total number of the button that sensing button is reliably pressed is restricted.Look the type of the type of key-press matrix and employed resistor and decide on accuracy and other factor of the current measurement circuit in the baseband processor 35, the maximum number of the button that can detect reliably can be less than 60, perhaps can be less than 50, and in some cases, be about 30.Some cellular phones comprise 30 above buttons.For instance, some cellular phones comprise the standard qwerty keyboard that relates to about 50 buttons.Under the situation of the key-press matrix with so many button, the circuit of Fig. 3 may not be worked or can't work at all preferably.
Summary of the invention
When the button on the matrix that pushes button, drive first electric current and pass first current path: from first common node, pass described key-press matrix, and to second common node.Between the flow periods of described first electric current electrical feature being carried out first measures.In an example, measure the resistance of first current path.Next, when still just pressing described button, drive second electric current and pass second current path: from described second common node, pass described key-press matrix, and to described first common node.Between the flow periods of described second electric current electrical feature being carried out second measures.In an example, measure the resistance of described second current path.Then, use first measurement and second to measure and discern the button of being pressed.Each button on the key-press matrix is corresponding to unique a pair of first measured value and second measured value.
In some instances, nonlinear resistive network is placed in the place, end of the column conductor and the row conductor of described key-press matrix.One example of nonlinear resistive network is the resistor that is connected in parallel with diode.The resistor that another example of nonlinear resistive network is connected in parallel for the transistor with the suitable control of warp.Nonlinear resistive network is positioned in the circuit, make when between first common node and second common node, having first polarity of voltage and supressing a button, so with in the nonlinear resistive network at place, the end of row conductor the two compare, in the nonlinear resistive network at the place, end of column conductor, first have low-down resistance.By at the resistance of measuring first current path between first common node and second common node under this first polarity condition, be independent of described first nonlinear resistive network in fact and measure the resistance of second nonlinear resistive network.Nonlinear resistive network is positioned in the circuit, make when the following time of condition that still is at second polarity of voltage opposite of existence between first common node and second common node and described button through pressing with described first polarity of voltage, then compare with first nonlinear resistive network, second nonlinear resistive network has low-down resistance.By at the resistance of measuring second current path between first common node and second common node during this second polarity condition, be independent of described second nonlinear resistive network in fact and measure the resistance of first nonlinear resistive network.Because the resistance of described nonlinear resistive network is through measuring independently of one another, therefore which single button the baseband processor integrated circuit that is coupled to the key-press matrix circuit by two terminals (terminal is coupled to described first common node, and another terminal is coupled to described second common node) only can determine to supress on described key-press matrix.
It is said that described baseband processor integrated circuit has " the two-wire connection " to described key-press matrix.The resistance by suitably selecting described nonlinear resistive network and the value of tolerance limit, described baseband processor integrated circuit also can detect two buttons pressing simultaneously on the described key-press matrix.In the embodiment that does not comprise independent key scan controller IC, two-wire connects from conventionally need need be in order to the number of the terminal of carrying out the key scan function in order to be situated between with the large-scale key-press matrix with many buttons that the big figure that connects reduces on the baseband processor integrated circuit.Therefore the cost of baseband processor integrated circuit can be reduced, because can reduce the number of the terminal in the encapsulation of baseband processor integrated circuit.In an example, described nonlinear resistive network is placed on the novel integrated circuit as the integrated circuit that is different from described baseband processor integrated circuit.The novel integrated circuit that is added has added cost to mobile communications device, but described cost is lower than the cost that conventional dedicated button scanning monitor integrated circuit is provided in mobile communications device.
Aforementioned for [summary of the invention] and therefore (necessarily) contain simplification, summary and the omission of details.Therefore, it will be understood by one of ordinary skill in the art that this [summary of the invention] only for illustrative and and do not mean that have restricted.In non-limiting [embodiment] stated in this article, the device described herein that defines by claims and/or others, invention feature and the advantage of method will only be understood.
Description of drawings
Fig. 1 (prior art) is the sketch of the first conventional cellular phone key scanning circuit.
Fig. 2 (prior art) is the sketch of the second conventional cellular phone key scanning circuit.
Fig. 3 (prior art) is the sketch of the 3rd conventional cellular phone key scanning circuit.
Fig. 4 (prior art) is during different key is pressed condition, the SENSE+ terminal of the baseband processor integrated circuit of Fig. 3 and the form of the resistance between the SENSE-terminal.
Fig. 5 is the figure according to the mobile communications device of a novel aspect.
Fig. 6 is the figure of first example of the interior keyboard scanning system of the mobile communications device of Fig. 5.
Fig. 7 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix of Fig. 6.
Fig. 8 is the figure of second example of the interior keyboard scanning system of the mobile communications device of Fig. 5.
Fig. 9 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix of Fig. 8.
Figure 10 is the figure of the 3rd example of the interior keyboard scanning system of the mobile communications device of Fig. 5.
Figure 11 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix of Figure 10.
Figure 12 is the figure of the 4th example of the interior keyboard scanning system of the mobile communications device of Fig. 5.
Figure 13 is the figure of the inclusion of the novel integrated circuit in the 4th example of explanation Figure 12.
Figure 14 presses the form of the resistance range of condition at the various buttons of the 4th example of the keyboard scanning system of Figure 12 for explanation first current path and second current path.
Figure 15 is the flow chart according to the novel method of another novel aspect.
Embodiment
Fig. 5 is the figure of mobile communications device 100.In the case, mobile communications device 100 is a cellular phone.Mobile communications device 100 comprises key-press matrix 101.In illustrated example, key-press matrix 101 comprises alphanumeric key disc portion and other button.Described alphanumeric key disc portion has the qwerty keyboard layout.The upper left quarter that letter " QWERTY " is illustrated in the alphanumeric key disc portion begins, and proceeds to the letter of right button from a left side along the top row of button.Key-press matrix 101 comprises alpha numeric keys and other button that amounts to 40 above buttons.
Fig. 6 is the sketch according to first example of the keyboard scanning system in the mobile communications device 100 of first novel aspect.Keyboard scanning system 102 comprises baseband processor integrated circuit 103, first common node 104, second common node 105, eight resistor 106-113, four diode 114-117 and key-press matrix 101.The resistor that is connected in parallel with diode is an example that is called as " nonlinear resistive network " herein.Reference number 128-131 discerns four these type of nonlinear resistive networks.For instance, baseband processor integrated circuit 103 can have the framework of the MSM7600 baseband processor that can buy from the Qualcomm Incorporated in Santiago in California.By being called as the interface of two-wire key matrix interface herein, baseband processor integrated circuit 103 is coupled to key-press matrix 101.
Key-press matrix 101 comprises four horizontally extending column conductor 118-121, four vertically extending row conductor 122-125 and ten six press keys.Term " OK " and " horizontal-extending " and " row " and " vertical extent " are the concept nature purpose that is used to simplify the explanation of circuit herein.However, it should be understood that as long as the electrical connection of Fig. 6 is maintained then Shi Ji column conductor and row conductor can wriggle and be directed on either direction.In described figure, ten six press keys are expressed as " 0 " arrive " 15 ".Each button is placed on the corresponding crosspoint of column conductor and row conductor, if make and press described button, then described column conductor is coupled to described row conductor.For instance, if push button " 5 ", then column conductor 119 is coupled to row conductor 123.In described explanation, because the restriction in space among the figure, ten six press keys in many buttons of key-press matrix 101 only are described.However, it should be understood that key-press matrix 101 has the button more than 40, and generally include four above column conductors and generally include four above row conductors.
In operation, with respect to second common node 105, the low-power sensing circuit in the baseband processor integrated circuit 103 is positioned over positive voltage on first common node 104.For instance, the low-power sensing circuit can comprise current providing circuit, and it can be with driven to the SENSE1 terminal; And analog comparator, it can detect the change on the resistor in the current path that receives the input current in the SENSE2 terminal.The mode that has many suitable realization low-power sensing circuits.Most of the time in mobile communications device 100 operations, there is no button and just be pressed.Therefore, do not exist in fact from the electric current of first common node, 104 to second common node 105.
Yet if supress button, described low-power sensing circuit detects the more accurate sensing circuit in current condition and the startup baseband processor 103.For instance, described more accurate sensing circuit can comprise Digital Logic, the current mirror of the electric current that can be outside SENSE2 or SENSE1 terminal receives on the current providing circuit, mirror resistor of supply of current and measure the AD converter of the voltage that lands on the described resistor.The mode that has many suitable more accurate sensing circuits of realization.
Described more accurate sensing circuit at first drive first electric current from SENSE1 terminal 126, pass first common node 104, pass key-press matrix 101, pass second common node 105 and to the SENSE2 terminal 127 of baseband processor integrated circuit 103.Consider the push button situation of " 5 " of the user of mobile communications device 100 wherein.More accurate sensing circuits in the baseband processor integrated circuit 103 drive first electric current and pass first current path: from SENSE1 terminal 126, pass first common node 104, pass diode 115, to column conductor 119, cross over the Closing Switch connection that forms by button " 5 ", to row conductor 123, pass resistor 111, pass second common node 105 and to SENSE2 terminal 127.For simplicity, suppose that diode 115 serves as desirable diode, its do not have forward bias voltage drop bypasses and when its anode with respect to its negative electrode be timing through forward bias, then diode 115 flows through resistor 107 through forward bias and no current.Therefore the all-in resistance of this first current path is 1R '.1R ' is the resistance of row conductor 111.More accurate sensing circuit in the baseband processor 103 is measured the electrical feature of this first current path.In an example, electrical feature is a resistance, and described sensing circuit determines that resistance is 1R '.By placing known voltage (for example, 2.0 volts) between SENSE1 terminal and the SENSE2 terminal and measuring the electric current between described two terminals, flow through and measuring resistance.
Behind the electrical feature of having measured first current path, described more accurate sensing circuit drives second electric current and passes second current path: from SENSE2 terminal 127, pass second common node 105, pass resistor 111, to row conductor 123, cross over the Closing Switch connection that forms by button " 5 ", to column conductor 119, pass resistor 107, pass first common node 104 and to SENSE1 terminal 126.Suppose that once more diode 115 is desirable diode, then diode 115 flows through diode 115 through reverse bias and no current.Therefore the resistance of this second current path add 1R ＂ for 1R '.1R ＂ is the resistance of resistor 107.More accurate sensing circuit in the baseband processor 103 is measured the electrical feature of this second current path.In an example, electrical feature is a resistance, and described sensing circuit determines that resistance is that 1R ' adds 1R ＂.By placing known voltage (for example, 2.0 volts) between SENSE2 terminal and the SENSE1 terminal and measuring the electric current between described two terminals, flow through and measuring resistance.
Resistor values 106-113 is through selecting so that each is unique to first current path resistances and second current path resistances.It is the button that is pressed that described sensing circuit uses described which person that measured value is discerned in the button.Diode 114-117 allows to measure the resistance of row resistor 110-113 under the influence that does not have capable resistor 106-109.Row resistor 110-113 has in fact the resistance less than the resistance of row resistor 106-109, make when second electric current when second common node 105 flows to first common node 104, the resistance of second current path will be in to be discerned and conducts in the resistance range of second electric current for which particular row resistor.No matter which row resistor is just conducting described second electric current, and the resistance of second current path will be in this resistance range.
Fig. 7 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix 101 of Fig. 6.For instance, if note that Fig. 7 indicates supresses " 5 " button, then resistance and second current path of first current path with 1R ' has the resistance that 1R ' adds 1R ＂.In described form, " R-〉C " represent electric current from the column conductor to the row conductor, and " C-〉R " represent that electric current is from the row conductor to the column conductor.Form 7 statement (for example) wherein R ' is that 1 kilohm and R ＂ are 10 kilohms current path resistances.Note that the first current path resistances value is 0 kilohm, 1 kilohm, 2 kilohms and 3 kilohms.Current sensing circuit needs to distinguish four different resistance, is included in described first current path so that determine which person in the row resistor.Note that the second current path resistances value is grouped into four groups.First group (0 kilohm, 1 kilohm, 2 kilohms and 3 kilohms) separate 7 kilohms with second group (10 kilohms, 11 kilohms, 12 kilohms and 13 kilohms).Similarly, separate 7 kilohms with the 3rd group (20 kilohms, 21 kilohms, 22 kilohms and 23 kilohms) for second group.Similarly, separate 7 kilohms with the 4th group (30 kilohms, 31 kilohms, 32 kilohms and 33 kilohms) for the 3rd group.Therefore, current sensing circuit needs to distinguish four different resistance ranges, is included in described second current path so that determine which person in four capable resistors.By making R ＂ more much bigger than R ', can make four gaps between the resistance range bigger, help therefrom to distinguish the task of a resistance range whereby.
In the custom circuit of Fig. 3, may be difficult to determine to have selected which row, because the resistance difference between two adjacent column may be in the tolerance limit of bigger capable resistor.Yet in the circuit of Fig. 6, the resistance that is independent of capable resistor owing to diode 114-117 is measured the resistance of row resistor.Digital processing units in the baseband processor integrated circuit 103 use the resistance measurement of the resistance measurement of first current path and second current path to determine to supress which button of key-press matrix 101.
Fig. 8 is the sketch according to second example of the keyboard scanning system of second novel aspect in mobile communications device 100.Keyboard scanning system 200 has the identical general structure of general structure with the system 102 of Fig. 6, but the system 200 of Fig. 8 comprises four additional diodes 201-204.
In operation, as in the embodiment of Fig. 6, with respect to second common node 105, the low-power sensing circuit in the baseband processor integrated circuit 103 is positioned over positive voltage on first common node 104.If supress button, then described low-power sensing circuit detects the more accurate sensing circuit in a current condition and the startup baseband processor 103.More accurate sensing circuit at first drive first electric current from SENSE1 terminal 126, pass first common node 104, pass key-press matrix 101, pass second common node 105 and to the SENSE2 terminal 127 of baseband processor integrated circuit 103.Consider the push button situation of " 5 " of the user of mobile communications device 100 wherein.More accurate sensing circuits in the baseband processor integrated circuit 103 drive first electric current and pass first current path: from SENSE1 terminal 126, pass first common node 104, pass diode 115, to column conductor 119, cross over the Closing Switch connection that forms by button " 5 ", to row conductor 123, pass resistor 111, pass second common node 105 and to SENSE2 terminal 127.For simplicity, suppose that diode 115 and 202 is desirable diode, then diode 115 flows through resistor 107 through forward bias and no current.Diode 202 flows through diode 202 through reverse bias and no current.Therefore the all-in resistance of this first current path is 1R '.1R ' is the resistance of resistor 111.More accurate sensing circuit in the baseband processor 103 is measured the electrical feature of this first current path.In an example, electrical feature is a resistance, and described sensing circuit determines that resistance is 1R '.
Behind the electrical feature of having measured first current path, described more accurate sensing circuit drives second electric current and passes second current path: from SENSE2 terminal 127, pass second common node 105, pass diode 202, to row conductor 123, cross over the Closing Switch connection that forms by button " 5 ", to column conductor 119, pass resistor 107, pass first common node 104 and to SENSE1 terminal 126.Suppose that once more diode 202 and 115 is desirable diode, diode 202 flows through resistor 111 through forward bias and no current.Diode 115 is through reverse bias, so no current flows through diode 115.Therefore the resistance of this second current path be 1R '.1R ' is the resistance of resistor 107.More accurate sensing circuit in the baseband processor 103 is measured the electrical feature of this second current path.In an example, electrical feature is a resistance, and described sensing circuit determines that resistance is 1R '.
Owing to the effect of diode 114-117 and 201-204, be independent of the resistance of row resistor 110-113 and measure the resistance of capable resistor 106-109, and be independent of the resistance of capable resistor 106-109 and measure the resistance of row resistor 110-113.In the example of supressing button " 5 ", diode 115 is shunted first electric current around resistor 107, makes to be independent of the resistance of resistor 107 and to measure the resistance of row resistor 111.A value and other value that sensing circuit must be able to be distinguished among row resistor values 0R ', 1R ', 2R ' and the 3R ' with definite which row resistor packages are contained in first current path.Similarly, diode 202 is shunted second electric current around resistor 111, makes to be independent of the resistance of resistor 111 and to measure the resistance of capable resistor 107.A value and other value that sensing circuit must be able to be distinguished among capable resistor values OR ', 1R ', 2R ' and the 3R ' with definite which resistor packages are contained in second current path.
Fig. 9 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix 101 of Fig. 8.For instance, if note that Fig. 9 indicates supresses " 5 " button, then first current path has the resistance of 1R ' and the resistance that second current path has 1R '.In described form, " R-〉C " represent electric current from the column conductor to the row conductor, and " C-〉R " represent that electric current is from the row conductor to the column conductor.Yet, in the embodiment of Fig. 6 and Fig. 7, more accurate sensing circuit must can sensing range from about zero ohm to about 33 kilohms resistance, the more accurate sensing circuit among the embodiment of Fig. 8 and Fig. 9 only need can sensing range from about zero ohm to about 3 kilohms resistance (R ' is 1 kilohm example).In this 0 kilohm to 3 kilohms scopes, it only needs to determine the resistance that is detected belongs among which person in four resistance ranges.Compare with the harsh designing requirement to the accurate sensing circuit among the embodiment of Fig. 6 and Fig. 7, this makes oversimplifies the designing requirement of accurate sensing circuit.The example that note that Fig. 6 and Fig. 8 adopts zero resistance value.Yet, in other example, do not have zero resistance value.For instance, in Fig. 8, the row resistor values can be 1 kilohm, 2 kilohms, 3 kilohms and 4 kilohms, and the row resistor values can be 1 kilohm, 2 kilohms, 3 kilohms and 4 kilohms.
Though for the purpose of the explanation of simplifying circuit operation the diode in the circuit of Fig. 6 and Fig. 8 is discussed as desirable diode hereinbefore, should be understood that described diode and nonideal but be actual diode.Described diode can be the diode or the rectifier element of silicon diode, germanium diode, Schottky (Schottky) diode or another type.Actual diode has forward drop and has non-linear current to voltage (IV) feature.In order to reduce the power consumption in the key scanning circuit, may need first electric current and second electric current are remained little current value.Yet, under low current, may be large enough to the measurement of the resistance of the capable resistor of interfered circuit and row resistor through the resistance of forward bias diode.
Figure 10 is the sketch according to the 3rd example of the keyboard scanning system of the 3rd novel aspect in mobile communications device 100.Keyboard scanning system 300 has the identical general structure of structure with the system 200 of Fig. 8, eight the diode 114-117 of Fig. 8 and 201-204 but the system 300 of Figure 10 comprises eight N channel field effect transistors 301-308.The gate coupled of transistor 301-304 together and be coupled to second common node 105.The gate coupled of transistor 305-308 together and be coupled to first common node 104.
The embodiment of Figure 10 is to operate with the similar mode of the embodiment of Fig. 8, but except the following situation: when the more accurate sensing circuit in the baseband processor 103 was positioned over positive voltage on the SENSE1 terminal 126 with respect to SENSE2 terminal 127 during button is pressed incident, the positive voltage on first common node 104 was coupled to the grid of transistor 305-308 by conductor 309.In one embodiment, on first common node 104, there are 2.0 volts and on second common node 105, have earthing potential.Therefore transistor 305-308 is connected and become has conductibility.On the other hand, the grid of transistor 301-304 remains in earthing potential owing to it is coupled to second common node 105 by conductor 310.Therefore transistor 301-304 disconnects and is non-conduction.Therefore, if button during this condition " 5 " is in the state through pressing, then first electric current from SENSE1 terminal 126, pass first common node 104, pass resistor 107, pass column conductor 119, cross over the Closing Switch connection that forms by button " 5 ", to row conductor 123, pass conductive transistor 306, pass second common node 105 and flow to SENSE2 terminal 127.Conductive transistor 306 is shunted first electric current around resistor 111.The all-in resistance of this first current path be resistor 107 resistance R '.Accurate sensing circuit in the baseband processor 103 is measured the electrical feature (for example, resistance) of this first current path.
Next, during this button was pressed incident, the accurate sensing circuit in the baseband processor 103 was positioned over positive voltage on the SENSE2 terminal 127 with respect to SENSE1 terminal 126.Positive voltage on second common node 105 is coupled to the grid of transistor 301-304 by conductor 310.On second common node 105, there are 2.0 volts, and on first common node 104, have earthing potential.Therefore transistor 301-304 is connected and become has conductibility.On the other hand, the grid of transistor 305-308 remains in earthing potential owing to it is coupled to first common node 104 by conductor 309.Therefore transistor 305-308 is disconnected and for non-conduction.Under these conditions, when button " 5 " is in the state that is pressed, second electric current from SENSE2 terminal 127, pass second common node 105, pass resistor 111, pass row conductor 123, cross over the Closing Switch connection that forms by button " 5 ", to column conductor 119, pass conductive transistor 302, pass first common node 104 and flow to SENSE1 terminal 126.Conductive transistor 302 is shunt current around resistor 107.The all-in resistance of this second current path be resistor 111 resistance R '.Accurate sensing circuit in the baseband processor 103 is measured the electrical feature (for example, resistance) of this second current path.Sensing circuits in the baseband processor 103 then use the measurement of first current path and second current path to determine to supress which button in the button of key-press matrix 101.
Figure 11 is for illustrating first current path and second current path form at the corresponding resistance of each button that is pressed on the key-press matrix 101 of Figure 10.Figure 11 is identical with Fig. 9.Yet, diode 114-117 among Fig. 8 and 201-204 can have the forward bias resistance of the measurement that is large enough to disturb first and second current path under low current conditions, transistor 301-304 among Figure 10 and 305-308 through control be essentially conduction or be essentially non-conduction.The size of transistor 301-304 and 305-308 is through designing so that the conducting resistance of its drain-to-source (Rds (on)) is compared very low with resistance value R '.Therefore, but can operate the embodiment of Figure 10 by the value of first and second electric current of value of first and second electric current that use is lower than the embodiment of application drawing 8.
In the embodiment of Fig. 6, Fig. 8 and Figure 10, resistor and diode and transistor can be on the printed circuit board (PCB) (PCB) that is placed in mobile communications device 100 or the discrete component on the flexible print circuit (FPC).Resistor and diode and transistor can be the assemblies as the part of key-press matrix 101.Yet, any one resistor, diode and the transistor among the embodiment of Fig. 6, Fig. 8 and Figure 10 can be integrated on the integrated circuit among other embodiment.
Figure 12 is the sketch according to the 4th example of the keyboard scanning system in mobile communications device 100 of "four news" (new ideas grain husk aspect.Except baseband processor integrated circuit 103 and key-press matrix 101, keyboard scanning system 400 also comprises novel integrated circuit 401.Figure 13 is the figure of the inclusion of the novel integrated circuit 401 of explanation.Use the novel integrated circuit 401 of standard CMOS semiconductor technology manufacturing and its to comprise a terminal at each column conductor among the column conductor 118-121 of key-press matrix 101.Reference number 402-405 among Figure 12 represents these terminals.Integrated circuit 401 also comprises a terminal at each row conductor among the row conductor 122-125 of key-press matrix 101.Reference number 406-409 among Figure 12 represents these terminals.Integrated circuit 401 also has the terminal 410 of the SENSE1 terminal 126 that is used to be coupled to first common node 104 and baseband processor integrated circuit 103.Integrated circuit 401 also has the terminal 411 of the SENSE2 terminal 127 that is used to be coupled to second common node 105 and baseband processor integrated circuit 103.
As indicated in Figure 13, the circuit of integrated circuit 401 is the integrated of the resistor of embodiment of Figure 10 and transistor circuit, but extra reference resistor 412 is provided.First lead of resistor 412 is coupled to first common node 104 and second lead of resistor 412 is coupled to second common node 105.Resistor is that (for example, polyresistor among the embodiment of) Figure 12 and Figure 13, the relative resistance of each resistor R 1-R9 tends to mutual tracking to integrated resistor, but the absolute resistance of described resistor can change with technology, voltage and temperature therein.By the measurement of baseband processor integrated circuit is the actual resistance of first current path and second current path.Therefore sensing circuit in the baseband processor 103 measures the resistance in the time durations reference resistor 412 of not pressing any button.Even therefore each person among the transistor 301-308 can connect and be what conduct, also no current can flow through key-press matrix 101.Measured resistance is then in order to be aligned in during the button detecting operation measurement to first electric current and second electric current.Except the periodic measurement of reference resistance 412 and the calibration that is associated, operating in to a great extent among the embodiment with Figure 10 of the sensing circuit in the baseband processor integrated circuit 103 is identical.Press condition for each button, the resistance of the reference resistor 412 in the specific embodiment of Figure 12 and Figure 13 and first current path and also in parallel with the resistance of second current path.Therefore the resistance of reference resistor 412 influences the value of measured resistance, but different resistance in hamper measurements first current path and second current path and to suitably distinguishing each other not.
Therefore though integrated circuit 401 is provided to relates to another integrated circuit in the mobile communications device 100 and add unacceptable cost to mobile communications device 100, but the manufacturing cost of integrated circuit 401 can significantly not provide the cost costliness of dedicated button scanning monitor integrated circuit (for example, the key scan controller IC 12 of Fig. 2).Novel integrated circuit 401 is very simple, and key scan controller IC 12 comprises significantly a large amount of Digital Logic usually.For instance, existing key scan controller can be the microcontroller that relates to processor and memory and other interface circuit.Perhaps, existing key scan controller can relate to the single user state machine and the interface circuit of Digital Logic.This some existing key scan controller manufactures more complicated than ball bearing made using depicted in figure 13 and is therefore more expensive.In addition, this supplier who has the key scan controller a bit now obtains profit from the sale of its key scan controller usually.For the manufacturer of mobile communications device 100, this profit is changed into higher manufacturing cost.By novel integrated circuit 401 usefulness being made the substitute to the common key-press scanning monitor, the manufacturer of mobile communications device 100 can reduce the cost of described mobile communications device, the profit of its reduction amount for will originally paying key scan controller supplier.
In the above description of the circuit of Fig. 6, Fig. 8 and Figure 10, supposed to make resistor have accurate resistance indicated on the figure.Yet when making side circuit, the actual resistance utensil has the different resistance that belong in the scope.Resistance is called in " tolerance limit ".For instance, the given resistor that will have a nominal resistance of 10 kilohms can in fact have variation up to 10 resistance.The resistor of various tolerance limits that can obtain resistance variations.For instance, can use resistance variations 10 or still less, 5 percent or still less, one of percentage or resistor still less.In the embodiment of Fig. 6, value and tolerance limit make that under the change of all conditions and actual resistance device value baseband processor integrated circuit 103 interior sensing circuits can be determined suitably that first electric current flows through its row resistor and can determine suitably that second electric current flows through its capable resistor to resistor to have so through selecting.Actual resistance overlapping that does not have resistor 110-113.Between four group of second current path resistances of Fig. 7, do not exist overlapping.Similarly, in the embodiment of Fig. 8, resistor values and tolerance limit through selecting so that do not exist overlapping between the actual resistance of the resistor 106-109 that is expert at and make between the actual resistance of row resistor 110-113, do not exist overlapping.Similarly, in the embodiment of Figure 10, resistor values and tolerance limit through selecting so that do not exist overlapping between the actual resistance of the resistor 106-109 that is expert at and make between the actual resistance of row resistor 110-113, do not exist overlapping.
Figure 14 presses the form of the resistance range of condition at each the single button among the embodiment of Figure 12 and Figure 13 for explanation first current path and second current path.Resistance range is (5%) 5 percent resistors owing to resistor R 1-R9.As can be seen from Fig. 14, when by next single button, the resistance of current path (first current path or second current path) is in the scope in four not overlapping scopes.First scope is 864 ohm to 955 ohm.Second scope is 1713 ohm to 1893 ohm.The 3rd scope is 2357 ohm to 2605 ohm.The 4th scope is 3037 ohm to 3357 ohm.Because none person and another person are overlapping in these four scopes, so the sensing circuit in the baseband processor integrated circuit 103 can suitably be distinguished resistance that is detected in the scope and the resistance that is detected in another scope.Measure and the affiliated scope of second current path measurement by definite first current path, sensing circuit is discerned the row of described form, and discerns the specific keys that is pressed from described row.
Yet Figure 14 also illustrates another novel aspect of the embodiment of Figure 12 and Figure 13: sensing circuit can determine to supress simultaneously two buttons.The difference of two buttons that the bottom 12 row statements in the described form can be pressed is arranged.For instance, in " button of being pressed (KEY (S) PRESSED) " row have clauses and subclauses " row 1 with row 2 (COL 1AND COL 2) " if the row indication supress a button in the first row button and supress a button in the secondary series button simultaneously, the resistance of first current path resistance range that will be in then.The resistance range that note that 611-675 ohm not with the condition that is pressed at arbitrary single button during the resistance range of first electric current overlapping.Similarly, no matter the row indication subsequently that note that Figure 14 supresses which button in the button of two different lines, the resistance of first current path will be not with the condition of pressing at arbitrary single button during resistance range overlapping.Therefore, be not in corresponding to single button and press in arbitrary scope in the resistance range of (or do not have button and press) condition if sensing circuit is carried out the measurement of the resistance of first current path and detected a resistance, then described sensing circuit determines to have supressed two buttons.Similarly, the resistance range of the bottom six of Figure 14 row indications second current path when supressing wantonly two two buttons in capable simultaneously.And the resistance range of second current path of statement is not overlapping with arbitrary resistance range of second current path when supressing any single button in last six row of described form.Therefore, be not at single button and press in arbitrary scope in the resistance range of (or do not have button and press) condition if sensing circuit is carried out the measurement of the resistance of second current path and detected a resistance, then described sensing circuit determines to have supressed two buttons.
Figure 15 is the simplified flow chart according to a method of a novel aspect.During button is pressed condition, drive first electric current and pass first current path, from first common node, pass key-press matrix, and to second common node (step 500).Between the flow periods of this first electric current, carry out first of electrical feature and measure (step 501).In an example, described electrical feature is the resistance of first current path.Next, during same key is pressed condition, drive second electric current and pass second current path, from described second common node, pass described key-press matrix, and to described first common node (step 502).Between the flow periods of described second electric current, carry out second of electrical feature and measure (step 503).Then, use first measurement and second result who measures to discern which button (step 504) of supressing key-press matrix.In some examples of the method for Figure 15,, then use first to measure and second measure and determine to supress simultaneously an above button if during carrying out two measurements, supress two buttons simultaneously.In an example of the method for Figure 15, the two-wire key matrix interface in the baseband processor integrated circuit on two-wire connects with first electric current and second current drives to described key-press matrix, wherein said key-press matrix comprises 30 above buttons.Yet described two-wire key matrix interface and related bidirectional key scanning circuit need not to be used in the baseband processor integrated circuit, but have extensive applicability and can and make the part of many dissimilar integrated circuits.Described two-wire key matrix interface and related bidirectional key scanning circuit can dedicated button scanning monitor integrated circuit form realize.
Though described some specific embodiment for the purpose that instructs hereinbefore, the teaching of patent document has general adaptability and is not limited to above-mentioned specific embodiment.Except the said method and circuit that relate to non-linear non-complex resistance circuit, the complex nonlinear resistance circuit that can use in conjunction with the simple non-complex resistance among the embodiment of alternate figures 6, Fig. 8, Figure 10 and Figure 13 uses other similar two-way detection technology.For instance, the frequency band limits circuit unit can be incorporated among the embodiment of Fig. 3, make and under different frequency, to measure row impedance and row impedance independently.Electric capacity and/or inductance can be measured impedance at the first electric assembly at an end place of column conductor in order to allow to be independent of in fact in the impedance of the second electric assembly at an end place of row conductor, and vice versa.The first electric assembly and the second electric assembly can have the different frequency associated impedances.First electric current and second electric current can flow through key-press matrix on nonlinear resistive network has the same direction of frequency dependent impedance.For instance, under first frequency, the first frequency associated impedances is shunt current around first resistor, makes the resistance that can be independent of first resistor measure the resistance of second resistor.Under second frequency, the second frequency associated impedances is shunt current around second resistor, makes to be independent of the resistance that described second resistor is measured first resistor.Under two frequencies, the direction that electric current flows is identical.Though above described discrete resistor, described resistor can be provided as and make that it is the integral part of another part of printed circuit board (PCB) (PCB) or flexible print circuit (FPC) or key-press matrix or mobile communications device, but not be discrete component.The order that first electric current and second electric current are flowed is unimportant.Can at first drive first electric current passes key-press matrix or can at first drive second electric current and pass key-press matrix.Therefore, under the situation of the scope that does not break away from the claims of stating hereinafter, can put into practice various modifications, change and the combination of the various features of described specific embodiment.
Claims (38)
1. circuit, it comprises:
First common node;
First resistor, it has first lead and second lead, and described first lead is coupled to described first common node;
Second resistor, it has first lead and second lead, and described first lead is coupled to described first common node;
Second common node;
The 3rd resistor, it has first lead and second lead, and described first lead is coupled to described second common node;
The 4th resistor, it has first lead and second lead, and described first lead is coupled to described second common node;
Key-press matrix, it has first conductor, second conductor, the 3rd conductor, the 4th conductor, first button, second button, the 3rd button and the 4th button, wherein said first conductor is coupled to described second lead of described first resistor, wherein said second conductor is coupled to described second lead of described second resistor, wherein said the 3rd conductor is coupled to described second lead of described the 3rd resistor, wherein said the 4th conductor is coupled to described second lead of described the 4th resistor, pressing of wherein said first button causes described first conductor to be coupled to described the 3rd conductor, pressing of wherein said second button causes described first conductor to be coupled to described the 4th conductor, pressing of wherein said the 3rd button causes described second conductor to be coupled to described the 3rd conductor, and pressing of wherein said the 4th button causes described second conductor to be coupled to described the 4th conductor;
First diode, it has first lead, second lead, and described first lead is coupled to described first lead of described first resistor, and described second lead is coupled to described second lead of described first resistor; And
Second diode, it has first lead, second lead, and described first lead is coupled to described first lead of described second resistor, and described second lead is coupled to described second lead of described second resistor.
2. circuit according to claim 1, it further comprises:
The 3rd diode, it has first lead, second lead, and described first lead is coupled to described first lead of described the 3rd resistor, and described second lead is coupled to described second lead of described the 3rd resistor; And
The 4th diode, it has first lead, second lead, and described first lead is coupled to described first lead of described the 4th resistor, and described second lead is coupled to described second lead of described the 4th resistor.
3. circuit according to claim 1, wherein said first resistor has resistance R 1, wherein said second resistor has resistance R 2, wherein said the 3rd resistor has resistance R 3, and wherein said the 4th resistor has resistance R 4, and wherein R3 and R4 are the resistance that is different in essence, wherein R1 is greater than R3, wherein R1 is greater than R4, and wherein R2 subtracts R1 greater than R3, and wherein R2 subtracts R1 greater than R4.
4. circuit according to claim 2, wherein said first resistor has resistance R 1, wherein said second resistor has resistance R 2, wherein said the 3rd resistor has resistance R 3, and wherein said the 4th resistor has resistance R 4, and wherein R2 is greater than R1, and wherein R2 is greater than R3, wherein R4 is greater than R1, and wherein R4 greater than R3.
5. circuit according to claim 1, it further comprises:
Integrated circuit, it is driven into described second common node with first electric current from described first common node, and also second electric current is driven into described first common node from described second common node.
6. circuit according to claim 1, wherein said key-press matrix comprises 30 above buttons, if wherein described first common node has first polarity of voltage with respect to described second common node, the pressing of the arbitrary single button in then described 30 buttons causes and exists one to pass the current path of described key-press matrix to described second common node from described first common node.
7. circuit according to claim 1, wherein said key-press matrix comprises 30 above buttons, if wherein described first common node has first polarity of voltage with respect to described second common node, the pressing of a button in then described 30 buttons causes and exists one to pass first current path of described key-press matrix to described second common node from described first common node, wherein said first current path has first resistance, if and wherein described first common node has second polarity of voltage with respect to described second common node, then described button described pressed also to cause and exists one to pass second current path of described key-press matrix to described first common node from described second common node, and wherein said second current path has second resistance that is different from described first resistance.
8. circuit according to claim 1, wherein said key-press matrix comprise 30 above buttons, and described circuit further comprises:
If the device that is used for determining to supress single button then supresses which button of described key-press matrix, wherein said device is driven into described second common node with first electric current from described first common node, and also second electric current is driven into described first common node from described second common node.
9. circuit according to claim 8, wherein said device also be used for distinguishing press described button both situation with press the situation of single button.
10. circuit according to claim 2, wherein said key-press matrix comprise 30 above buttons, and described circuit further comprises:
If the device that is used for determining to supress single button then supresses which button of described key-press matrix, wherein said device is driven into described second common node with first electric current from described first common node, and also second electric current is driven into described first common node from described second common node.
11. circuit according to claim 10, wherein said device also be used for distinguishing press described button both situation with press the situation of single button.
12. circuit according to claim 1, it further comprises:
The 5th resistor, it has first lead and second lead, and described first lead is coupled to described first common node, and second lead is coupled to described second common node.
13. circuit according to claim 1, wherein said key-press matrix comprises 30 above buttons, and wherein said first resistor, second resistor, the 3rd resistor, the 4th resistor, first diode and second diode are integrated on the single integrated circuit.
14. circuit according to claim 2, wherein said key-press matrix comprises 30 above buttons, and wherein said first resistor, second resistor, the 3rd resistor, the 4th resistor, first diode, second diode, the 3rd diode and the 4th diode are integrated on the single integrated circuit.
15. a method, it comprises:
(a) driving first electric current passes from first common node, passes key-press matrix and to first current path of second common node, wherein when button in a plurality of buttons of pressing described key-press matrix, described first electric current flows through described first current path;
(b) carrying out first of electrical feature between the described flow periods of described first electric current in (a) measures;
(c) drive second electric current and pass from described second common node, pass described key-press matrix and to second current path of described first common node, wherein when pressing a described button, described second electric current flows through described second current path;
(d) carrying out second of electrical feature between the described flow periods of described second electric current in (c) measures; And
(e) use described first to measure and the described button of the described second measurement identification.
16. method according to claim 15, wherein said first current path has first resistance between described first common node and described two common node, wherein second current path has second resistance between described first common node and described second common node, and wherein said first resistance is different in essence in described second resistance.
17. method according to claim 15, wherein said first electric current mainly flows through resistor and does not flow through diode, first lead of described resistor is coupled to first lead of described diode, second lead of described resistor is coupled to second lead of described diode, and wherein said second electric current mainly flows through described diode and do not flow through described resistor.
18. method according to claim 15, wherein said key-press matrix comprise 30 above buttons.
19. method according to claim 15, wherein said electrical feature is taken from the group that is made up of the following: the voltage between the resistance between described first common node and described second common node, described first common node and described second common node, and the electric current that flows through between described first common node and described second common node.
20. method according to claim 15, wherein integrated circuit in (a), drive described first electric current, (c) drive described in second electric current, and in (e), discern a described button.
21. method according to claim 15, wherein said first electric current mainly flows through resistor and does not flow through transistor, first lead of described resistor is coupled to described transistorized first lead, second lead of described resistor is coupled to described transistorized second lead, and wherein said second electric current mainly flows through described transistor and does not flow through described resistor, wherein said transistor through control when described first electric current flows, being essentially non-conduction in (a), and wherein said transistor through control when described second electric current is mobile in (c), to be essentially conduction.
22. method according to claim 15, it further comprises:
(f) drive the 3rd electric current from described first common node, pass described key-press matrix and to described second common node, between the described flow periods of described the 3rd electric current, carry out the 3rd measurement of electrical feature, and use the described the 3rd to measure an above button determining to press simultaneously described key-press matrix.
23. a circuit, it comprises:
First common node;
First resistor, it has first lead and second lead, and described first lead is coupled to described first common node;
Second resistor, it has first lead and second lead, and described first lead is coupled to described first common node;
Second common node;
The 3rd resistor, it has first lead and second lead, and described first lead is coupled to described second common node;
The 4th resistor, it has first lead and second lead, and described first lead is coupled to described second common node;
Key-press matrix, it has first conductor, second conductor, the 3rd conductor, the 4th conductor, first button, second button, the 3rd button and the 4th button, wherein said first conductor is coupled to described second lead of described first resistor, wherein said second conductor is coupled to described second lead of described second resistor, wherein said the 3rd conductor is coupled to described second lead of described the 3rd resistor, wherein said the 4th conductor is coupled to described second lead of described the 4th resistor, pressing of wherein said first button causes described first conductor to be coupled to described the 3rd conductor, pressing of wherein said second button causes described first conductor to be coupled to described the 4th conductor, pressing of wherein said the 3rd button causes described second conductor to be coupled to described the 3rd conductor, and pressing of wherein said the 4th button causes described second conductor to be coupled to described the 4th conductor;
The first transistor, it has first lead, second lead, and described first lead is coupled to described first lead of described first resistor, and described second lead is coupled to described second lead of described first resistor; And
Transistor seconds, it has first lead, second lead, and described first lead is coupled to described first lead of described second resistor, and described second lead is coupled to described second lead of described second resistor.
24. circuit according to claim 23, it further comprises:
The 3rd transistor, it has first lead and second lead, and described first lead is coupled to described first lead of described the 3rd resistor, and described second lead is coupled to described second lead of described the 3rd resistor; And
The 4th transistor, it has first lead, second lead, and described first lead is coupled to described first lead of described the 4th resistor, and described second lead is coupled to described second lead of described the 4th resistor.
25. circuit according to claim 23, wherein said the first transistor has the control input lead, wherein said transistor seconds has the control input lead, and the described control input lead of wherein said the first transistor and described transistor seconds is coupled and also is coupled to described second common node.
26. circuit according to claim 24, wherein said the first transistor has the control input lead, wherein said transistor seconds has the control input lead, the described control input lead of wherein said the first transistor and described transistor seconds is coupled and also is coupled to described second common node, wherein said the 3rd transistor has the control input lead, wherein said the 4th transistor has the control input lead, wherein said the 3rd transistor and the described the 4th transistorized described control input lead are coupled, and also are coupled to described first common node.
27. circuit according to claim 23, wherein said first resistor has resistance R 1, wherein said second resistor has resistance R 2, wherein said the 3rd resistor has resistance R 3, and wherein said the 4th resistor has resistance R 4, and wherein R3 and R4 are the resistance that is different in essence, and wherein R1 is greater than R3 and R4, wherein R2 subtracts R1 greater than R3, and wherein R2 subtracts R1 greater than R4.
28. circuit according to claim 24, wherein said first resistor has resistance R 1, wherein said second resistor has resistance R 2, wherein said the 3rd resistor has resistance R 3, and wherein said the 4th resistor has resistance R 4, and wherein R2 is greater than R1, and wherein R2 is greater than R3, wherein R4 is greater than R1, and wherein R4 greater than R3.
29. circuit according to claim 23, wherein said key-press matrix comprises 30 above buttons, wherein during the arbitrary single button in pressing described 30 buttons, make first current path and second current path between described first common node and described second common node, extend through described key-press matrix at different time.
30. circuit according to claim 29, it further comprises:
Integrated circuit, it controls described the first transistor and described transistor seconds, thereby causes first electric current to flow in described first current path, and causes second electric current to flow in described second current path.
31. circuit according to claim 23, it further comprises:
Circuit, the identity of its definite button of being pressed when pressing single button, and it can distinguish the situation of pressing two buttons and the situation of pressing single button.
32. an integrated circuit, it comprises:
Two-wire key matrix interface, it is suitable for when the nonlinear resistive network of key-press matrix has first resistance, press incident drive first electric current at button and pass described nonlinear resistive network, and wherein said two-wire key matrix interface also is suitable for when the described nonlinear resistive network of described key-press matrix has second resistance, presses incident drive second electric current at described button and passes described nonlinear resistive network.
33. integrated circuit according to claim 32, wherein said two-wire key matrix interface comprises the first terminal and second terminal, wherein said two-wire key matrix interface is suitable for driving described first electric current to be left described the first terminal and described first electric current is received in described second terminal, and wherein said two-wire key matrix interface is suitable for driving described second electric current and leaves described second terminal and described second electric current is received in the described the first terminal.
34. integrated circuit according to claim 32, wherein said two-wire key matrix interface comprises the first terminal and second terminal, wherein said two-wire key matrix interface is suitable for driving described first electric current to be left described the first terminal and described first electric current is received in described second terminal, and wherein said two-wire key matrix interface is suitable for driving described second electric current and leaves described the first terminal and described second electric current is received in described second terminal.
35. integrated circuit according to claim 32, wherein said first electric current has first frequency, and wherein said second electric current has second frequency.
36. integrated circuit according to claim 32, wherein said integrated circuit determine to supress which button in a plurality of buttons of described key-press matrix during described button is pressed incident.
37. integrated circuit according to claim 36, wherein said nonlinear resistive network comprises:
Resistor, it has first lead and second lead; And
Diode, it has first lead and second lead, and described first lead of wherein said diode is coupled to described first lead of described resistor, and described second lead of wherein said diode is coupled to described second lead of described resistor.
38. integrated circuit according to claim 36, wherein said nonlinear resistive network comprises:
Resistor, it has first lead and second lead; And
Transistor, it has source electrode and drain electrode, and wherein said transistorized described source-coupled is to described first lead of described resistor, and wherein said transistorized described drain coupled is to described second lead of described resistor.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81529706P | 2006-06-20 | 2006-06-20 | |
| US60/815,297 | 2006-06-20 | ||
| US11/680,036 | 2007-02-28 |
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| CN101473543A true CN101473543A (en) | 2009-07-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2007800224072A Pending CN101473543A (en) | 2006-06-20 | 2007-06-19 | Two-wire connection to a key matrix in a mobile device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103455148A (en) * | 2012-05-31 | 2013-12-18 | 展讯通信（上海）有限公司 | Keyboard, key detecting method and mobile device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103455148A (en) * | 2012-05-31 | 2013-12-18 | 展讯通信（上海）有限公司 | Keyboard, key detecting method and mobile device |
| CN103455148B (en) * | 2012-05-31 | 2016-06-29 | 展讯通信（上海）有限公司 | A kind of keyboard and key detecting method and mobile equipment |
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