JP2008052620A - Capacitance type input device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitance type input device which can detect position information on an operation body and input information on a switch with a common circuit, and can reduce a load on a control unit during operation. <P>SOLUTION: If the operation body 50 such as a finger is moved to perform any operation of approaching to, contacting with, or depressing an electrostatic sensor 20, capacitance C according to each operation condition is generated between the operation body 50 and the electrostatic sensor 20. A detection circuit 30 detects the change of the capacitance C and thus outputs position information and input information according to each operation condition. Thereby, the control unit 40 can acquire the position information and input information on the operation body 50 from the output of the detection circuit 30. Accordingly, the load on the control unit 40 can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitance-type input device that detects the position of an operating body such as a finger by a change in capacitance, and in particular, a common circuit configuration for detecting position information of an operating body and detecting input information of a switch. It is related with the electrostatic capacitance type input device which enabled it to detect by.

  Patent Document 1 below discloses an input device that can perform a key input mode and a position input mode on the same operation surface.

  In this input device, when an operating body such as a finger approaches or contacts the surface of the display sheet, a capacitance C is formed between the operating body and the reversing member, while a reversing member that does not face the operating body No capacitance C is formed between the two. Therefore, it is possible to detect the position information of the operating tool by comparing the size of the capacitance C with the position detecting means.

When the display portion provided on the display sheet is pressed, the reversing member 12 is reversed and the lower surface of the reversing member 12 is brought into contact with the contact electrode, thereby enabling key input.
Japanese Patent Application Laid-Open No. 2004-334738

However, the input device described in Patent Document 1 has the following problems.
(1) Since the position detection means for detecting a change in capacitance and the means for detecting switching between ON and OFF of the switch are separate structures, it is difficult to simplify the circuit configuration.
(2) Since there is no need to perform mode switching between the position input mode and the key input mode, the control unit can detect the input from the position detecting means and the switch switching. It is necessary to simultaneously monitor inputs from the means, and the burden on the control unit cannot be reduced.

  The present invention is for solving the above-described conventional problems, and is a capacitance type that can detect the position information of the operating body and the detection of input information, which is switch switching, with a common circuit configuration. An object is to provide an input device.

  It is another object of the present invention to provide a capacitance type input device that can reduce the burden on the control unit during operation.

The present invention detects a substrate, a plurality of electrostatic sensors arranged on the substrate, position information based on the position of an operating body opposed to any one of the electrostatic sensors, and input information based on switch switching. A capacitance type input device having a detection circuit,
The electrostatic sensor includes a counter electrode provided inside with an opening from which a part of the substrate is exposed, a ground electrode provided inside the opening, and a base end fixed to the counter electrode. And a reversing member that is disposed opposite to the ground electrode and is reversed when pressed by an operating body and brought into contact with the ground electrode,
When the operating body approaches or comes into contact with any one of the electrostatic sensors, at least one of the operating body and the counter electrode and between the operating body and the reversing member is detected by the detection circuit. The position information and the input information are detected from the amount of change in capacitance formed on the substrate.

  In the present invention, the relative position information of the operating body that moves in opposition to the input device and the switch input information of the reversing member that is reversed and switched when the operating body is pressed are detected using a common detection circuit. be able to. Therefore, the circuit configuration of the detection circuit can be simplified.

  In addition, since the position information and the input information can be acquired simultaneously only by monitoring the output from the detection circuit, the burden on the control unit during operation can be reduced.

  Further, in the present invention, the reversing member functions as an electrode that forms an electrostatic sensor together with the counter electrode and forms a capacitance with the operating body. For this reason, in order to increase the sensitivity of the electrostatic sensor, it is not necessary to widen the area of the electrostatic sensor in advance. That is, since the electrode area required for obtaining a desired sensitivity per electrostatic sensor can be reduced, the overall size of the apparatus can be reduced.

  In the above, it is preferable that the reversal member is formed of a dome-shaped metal contact, and the surface of the metal contact and the surface of the counter electrode are covered with an insulating layer having a dielectric constant.

  When the reversing member is formed of a metal diaphragm as in the above-described means, a click feeling can be obtained and the reversing operation can be performed smoothly. Further, if the surface is covered with a dielectric, the capacitance generated between the counter electrode and the operating body and between the reversing member and the operating body can be increased, so that the detection accuracy of the input device can be improved. It becomes possible.

  For example, the detection circuit includes: a signal generation unit that outputs a pulsed input signal having a predetermined frequency; an integrator that receives the input signal; and a response signal that is an output of the input signal and the integrator. It can comprise as a calculation part which calculates the rise time of the said response signal, and the determination part which determines the operation state of the said electrostatic sensor from the rise time which the said calculation part calculated.

  In the above, the integrator may be configured to have a capacitance formed between the counter electrode, at least one of the reversing member, and the operation body, and a predetermined resistance.

  In the above means, whether or not the operating body has contacted at least one of the counter electrode and the reversing member can be captured as a change in capacitance formed therebetween.

  Further, the detection circuit obtains a change amount of the electrostatic capacitance from the previously calculated calculation data of the rise time of the electrostatic sensor and the calculation data of the rise time of the electrostatic sensor detected after that, and from the change amount, It is preferable that an operation state of the electrostatic sensor is determined and the input information is generated.

  For example, immediately after turning on the power, all the capacitance formed through the counter electrode and the reversing member is detected to obtain calculation data of the initial state, and the change in capacitance from the initial state The amount is detected. The calculation data indicating the amount of change in the capacitance is stored in the memory, and this calculation data is rewritten whenever new calculation data is detected.

  As described above, since the above-described means obtains the position information of the operating body and the input information of the switch from the amount of change in capacitance, highly accurate detection is possible.

  For example, the determination unit has a first reference value and a second reference value, and the operation state of the electrostatic sensor is such that the amount of change in the capacitance is less than the first reference value. In some cases, it is determined as a non-input state, when it is greater than or equal to the first reference value and less than or equal to the second reference value, it is determined as a contact state, and when it exceeds the second reference value, it is determined as an input state. It is what is done.

  The non-input state corresponds to a state where the operating body is separated from the reversing member (OFF state), and the contact state corresponds to a state where the operating body contacts the reversing member. Further, the input state corresponds to a state (ON state) in which the reversing member is pressed by the operating body and is in contact with the grounding member. Thus, the above means can detect three operating states. Therefore, various operations can be performed by combining them.

  In the present invention, detection of the position information of the operating body and detection of the input information of the switch can be detected using a common detection circuit.

  In addition, since the position information and the input information can be acquired simultaneously only by monitoring the output of the detection circuit, the burden on the control unit can be reduced.

  1 is a perspective view showing an electronic apparatus equipped with an input device as an embodiment of the present invention, FIGS. 2A to 2C are cross-sectional views taken along line 2-2 in FIG. 1, and FIG. 2A is a non-input state ( 2B shows a contact state, and FIG. 2C shows an input state (ON state). 3 is a block diagram showing an outline of the detection circuit in the present invention, FIG. 4 is a waveform diagram showing an outline of the input signal U to the integrator and its response signal W, A is a non-input state, and B is a contact state. , C are input states, and FIG. 5 is a plan view showing an operation state of the input device.

  The electronic device 1 shown in FIG. 1 is an image of a non-foldable portable phone. The electronic apparatus 1 has a case 3 that forms an appearance, and the case 3 is provided with a display panel 4 as display means and an input device 10 for performing key input and coordinate input. The display panel 4 is, for example, a liquid crystal panel or EL panel made of monochrome or color.

  As shown in FIGS. 1 and 2A to 2C, the input device 10 has a substrate 16, and a plurality of opposing surfaces arranged in a matrix (4 rows and 3 columns in FIG. 1) on the surface of the substrate 16. An electrode 21 is provided.

  One counter electrode 21 has a conductive layer (planar electrode) having a substantially square shape, and an opening 22 having no conductive layer is formed in a substantially circular shape inside the counter electrode 21. The surface of the substrate 16 is partially exposed at the opening 22, and a ground electrode 23 is provided at the inner center. The ground electrode 23 is led to the back surface (Z2 side surface) of the substrate 16 through a through hole 16a formed in the substrate 16, and is wired outside the substrate 16 along the back surface. .

  A reversing member 12 having a dome shape (or a diaphragm shape) is provided on the surface of the counter electrode 21. The reversing member 12 is formed of, for example, a so-called metal contact switch formed by punching a thin metal plate having conductivity (for example, a stainless steel plate) with a precision processing press, and can perform a crisp click operation. ing.

  A base end portion 12a which is an edge portion of the reversing member 12 is fixed to the surface of the counter electrode 21 by means of soldering or Au flash. For this reason, the counter electrode 21 and the reversing member 12 are electrically set at the same potential, and one set of the reversing member 12 and the counter electrode 21 form one electrostatic sensor 20. Yes.

  As shown in FIG. 2A, when the reversing member 12 is not pressed, a space S is formed between the bottom surface of the reversing member 12 and the ground electrode 23, and the reversing member 12 and the ground electrode are formed. 23 are separated from each other (electrically insulated).

  A thin sheet 11 is laminated on the upper surface of the substrate 16, and a plurality of the reversing members 12 and the ground electrode 23 are covered with the sheet 11.

  The sheet 11 is formed of an insulating and dielectric member such as PET (polyethylene terephthalate), and can be bent and deformed in a direction (Z direction) perpendicular to the surface. As shown in FIG. 1 and the like, a plurality of displays formed by printing or transferring characters such as 1, 2, 3,..., 0, *, #, or symbols on the sheet 11. 11a is provided.

  As shown in FIG. 2C, when any of the reversing members 12 is pressed in the Z1 direction using an operating body 50 such as a finger or a pen, the reversing members 12 are deformed and reversed. At this time, the reversing member 12 is reversed and the lower surface thereof contacts the ground electrode 23, and the reversing member 12 and the counter electrode 21 are switched to the same potential as the ground electrode 23. That is, the reversing member 12 functions as a switch. The detection of the switch switching operation will be described later.

  For example, a detection circuit 30 as shown in FIG. 3 is provided in the electronic apparatus 1. The detection circuit 30 shown in the present embodiment includes a signal generation unit 31, an integrator 32, a calculation unit 33, and a determination unit 34.

  The signal generator 31 is formed of an oscillation circuit that generates a pulsed input signal U (see FIG. 4) having a constant frequency, and supplies the input signal U to the integrator 32. The integrator 32 is formed of a resistor R and a capacitance C each having a predetermined resistance value. The resistor R is formed on a wiring line between the signal generator 31 and the capacitance C.

  The electrostatic capacitance C is formed by the electrostatic sensor 20, and the resistor R is connected to one end of the electrostatic sensor 20 (electrostatic capacitance C). The sheet 11 provided on the surface of the electrostatic sensor 20 forms the other end side of the capacitance C. For this reason, the other end of the capacitance C is in an electrically floating state in a non-input state where the operating body 50 is separated from the electrostatic sensor 20, and the operating body 50 approaches the electrostatic sensor. Alternatively, when the contact state or the input state comes into contact, the ground is made through the operator. That is, the capacitance C is formed between the operating body 50 and the electrostatic sensor 20 when the operating body 50 approaches or comes into contact with the sheet 11 covering the electrostatic sensor 20.

  Here, the magnitude of the capacitance C of each electrostatic sensor 20 is based on the relationship of C = ε · A / d (ε is a dielectric constant, A is a facing area, and d is a facing distance). It is proportional to the facing area between the electric sensor 20 and inversely proportional to the facing distance. Therefore, the capacitance C is larger as the facing area A is wider or the facing distance d is shorter, and conversely, the electrostatic capacity C is smaller as the facing area A is narrower or the facing distance d is longer.

  As shown in FIG. 3, the arithmetic unit 33 includes an AND circuit 33A that calculates a logical product of the input signal U input to the integrator 32 and a response signal W that is an output thereof, and the AND circuit 33A. A smoothing unit 33B that generates and smoothes a smoothing voltage E by integrating and smoothing the output on a predetermined time axis, and an A / D conversion unit 33C that converts the smoothing voltage E into calculation data D that is a digital value. The calculation result of the input signal and the response signal W is output from the calculation unit 33 as calculated data D after smoothing.

The smoothed calculation data D obtained in this way is stored in a memory 34a provided in the determination unit 34 as necessary. The determination unit 34 compares the calculation data _DN-1 previously recorded in the memory 34a with the calculation data D newly obtained this time. Result of the comparison, an output difference between the previous calculation data D _N-1 and the new calculated data D _N (the amount of change in the electrostatic capacitance _{C) (D N-1 -D} N) is within a predetermined range It is determined whether or not. At this time, the determination result made by the determination unit 34 is output to the control unit 40.

For example, the determination unit 34 prepares a first reference value and a second reference value that is larger than the first reference, and the range in which (D _N−1 -D _N ) is less than the first reference value. The operating state of the input device 10 is determined based on which of the range that is greater than or equal to the first reference value and less than or equal to the second reference value or greater than the second reference value. Note that. The controller 40 also performs a data update process for rewriting the previous calculation data _DN-1 stored in the memory 34a with the new calculation data D.

  Note that one detection circuit 30 as described above may be provided for one electrostatic sensor 20, but for example, the calculation unit 33 and the determination unit 34 for a plurality of electrostatic sensors 20 are provided. A common configuration may be used. For example, switching means (not shown) such as a multiplexer is provided between each output terminal 32a of the plurality of integrators 32 and the input terminal 33a of the arithmetic unit 33, and the outputs of the plurality of integrators 32 are time-divisionally divided. By switching and inputting to the input terminal 33a of the arithmetic unit 33, it is possible to realize commonality. In this case, it is not necessary to provide the calculation unit 33 and the determination unit 34 for each integrator 32, and the number of parts can be reduced. Therefore, it is possible to reduce the cost and the size.

The operation of the input device will be described below.
In the following, a state in which the operating body 50 is not positioned above the input device 10 and does not face any electrostatic sensor 20 is defined as a non-input state (OFF state) (see FIG. 2A). Further, although the operating body 50 is in contact with the reversing member 12 through the sheet 11, it is not pressed down, and therefore the reversing member 12 is not deformed and the lower surface of the reversing member 12 is connected to the ground electrode 23. The state that is not performed is defined as a contact state (see FIG. 2B). Then, the state in which the reversing member 12 is pressed by the operating body 50, the lower surface of the reversing member 12 is in contact with the ground electrode 23, and the two are electrically connected is defined as an input state (ON state) ( (See FIG. 2C).

  When power is supplied to the electronic device 1 on which the input device 10 is mounted, the detection circuit 30 is driven, and all the calculation data D formed via all the electrostatic sensors 20 are in the predetermined period. 34. The determination unit 34 sequentially stores new calculation data D while rewriting them in the memory 34a.

(1) Case of Non-Input State As shown in FIG. 2A, in the non-input state, the electrostatic capacitance C of the electrostatic sensor 20 constituting the integrator 32 is in an electrically floating state. That is, since the capacitance C is not formed, the input signal U is output as it is as the response signal W through the resistor R. That is, as shown in FIG. 4A, there is no delay between the input signal U and the response signal W, so that the output U · W of the AND circuit 33A is substantially the same as the input signal U.

At this time, the determination unit 34, compare whether the output difference between the previous calculation data D _N-1 and the new calculated data _{D N (D N-1 -D} N) is within a predetermined range To do. In this case, the output difference (D _N-1 −D _N ) is almost zero. For this reason, the determination unit 34 is in the switch OFF state in which the operating body 50 is separated from the reversing member 12 because the output difference (D _N-1 −D _N ) is less than the predetermined first reference value. Can be determined.

(2) In the Contact State As shown in FIG. 2B, when the operating body 50 comes into contact with any one of the electrostatic sensors 20, a capacitance C is formed between the electrostatic sensor 20 and the operating body 50. The For this reason, as shown in FIG. 4B, the response signal W is duller than the input signal U based on the time constant RC. That is, a delay occurs in the rise time of the response signal W.

At this time, new calculated data _{D N} indicate a value lower than the calculated data _{D N-1} of the destination _{(D N <D N-1} ). Therefore, the output difference to the previous calculation data _{D N-1} and the new calculated data _{D N (D N-1 -D} N) occurs. The determination unit 34 is a case where the output difference ( _{DN-1− DN} ) exceeds the first reference value but falls within a predetermined second reference value. It can be determined that the contact state is present.

(3) In the Input State As shown in FIG. 2C, when the reversing member 12 pressed by the operating body 50 is reversed and contacts the ground electrode 23, the signal line between the resistor R and the AND circuit 33A. Becomes the ground level. Therefore, the response signal W as shown in C in FIG. 4 is a 0, becomes also 0 [v] new calculated data D _N of the operational section 33 (D N _{= 0).} For this reason, the output difference (D _N-1 −D _N ) is _DN−1 , which corresponds to a case where the second reference value is exceeded. Therefore, the determination unit 34 can determine that the operating tool 50 is in the input state (switch ON state).

  As described above, in the input device of the present invention, the input device 10 changes from the output of the detection circuit 30 (output of the determination unit 34) to either the non-input state (switch OFF state) or the input state (switch ON state). It is possible to detect not only the presence but also three types of operation states including the contact state.

Next, detection of the position information of the operating tool will be described.
As described above, the capacitance C of each electrostatic sensor 20 is proportional to the facing area A between the operating body 50 and the electrostatic sensor 20 and inversely proportional to the facing distance d. For this reason, the dullness of the response signal W output from each electrostatic sensor 20 differs depending on the facing area A and the facing distance d between the operating body 50 and the electrostatic sensor 20, and accordingly The size of the calculation data D from the calculation unit 33 is also different.

  For example, as shown in FIG. 5, when the operating body 50 is brought close to the “7” display 11 a, the electrostatic capacitance C of the electrostatic sensor 20 provided at the position of the “7” display 11 a becomes the largest. . The next largest capacitance C is the electrostatic sensor 20 provided at the position of the “*” display 11a that partially overlaps the operating body 50 in the height direction. The electrostatic sensor 20 provided at the position of the display 11a of “4” or “8” having a short facing distance d from the distance tends to increase.

  Therefore, the determination unit 34 can obtain the position information of the operating tool 50 by comparing the magnitude relationship of the calculation data D from each electrostatic sensor 20. That is, when the determination unit 34 compares the calculation data D of all the electrostatic sensors 20 arranged in the matrix, the position of the electrostatic sensor 20 that indicates the largest value of the calculation data D is determined by the operation. The position of the body 50 is determined. Thereby, the detection circuit 30 can output the position information specifying the position of the operation body 50 toward the control unit 40. Thereby, the operating body 50 can detect which one of the plurality of electrostatic sensors 20 arranged in a matrix is opposed to the electrostatic sensor 20 (position information).

  As described above, in the capacitance type input device 10 of the present invention, the position information of the operating body 50 is detected, and the switching information of the reversing member 12 provided in each electrostatic sensor 20 (switch ON / OFF input information). ) Can be detected by the common detection circuit 30.

  Further, the control unit 40 can simultaneously acquire the position information and the input information only by monitoring the output from the detection circuit 30. For this reason, the burden of the control part 40 can be reduced compared with the past.

  In the above-described embodiment, the case of a form telephone has been described as the electronic apparatus 1 on which the input device 10 is mounted. However, the present invention is not limited to this, and for example, a digital audio player, a digital camera, a PDA ( Other electronic devices such as Personal Digital Assistants) may be used.

  In the above-described embodiment, the case where a plurality of electrostatic sensors 20 are arranged in a matrix has been described. However, the present invention is not limited to this, and other arrangement configurations may be used.

The perspective view which shows the electronic device carrying an input device as embodiment of this invention, 1 is a cross-sectional view taken along line 2-2 of FIG. 1 showing a non-input state (OFF state); FIG. 1 is a cross-sectional view taken along line 2-2 in FIG. Input state (ON state) cross-sectional view taken along line 2-2 in FIG. The block diagram which shows the outline of the detection circuit in this invention, It is a wave form diagram showing the outline of input signal U to an integrator, and its response signal W, A is a non-input state, B is a contact state, C is an input state, A plan view showing an operation state for the input device,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic device 10 Input device 11 Sheet | seat 11a Display 12 Inversion member 16 Board | substrate 20 Electrostatic sensor 21 Counter electrode 22 Opening part 23 Grounding electrode 30 Detection circuit 31 Signal generation part 32 Integrator 33 Operation part 33A AND circuit 33B Smoothing part 33C A / D conversion unit 34 determination unit 34a memory 40 control unit C capacitance R resistance U input signal W response signal

Claims (6)

A substrate, a plurality of electrostatic sensors arranged on the substrate, a detection circuit for detecting position information based on a position of an operating body opposed to any one of the electrostatic sensors and input information based on switching of a switch; A capacitance-type input device comprising:
The electrostatic sensor includes a counter electrode provided inside with an opening from which a part of the substrate is exposed, a ground electrode provided inside the opening, and a base end fixed to the counter electrode. And a reversing member that is disposed opposite to the ground electrode and is reversed when pressed by an operating body and brought into contact with the ground electrode,
When the operating body approaches or comes into contact with any one of the electrostatic sensors, at least one of the operating body and the counter electrode and between the operating body and the reversing member is detected by the detection circuit. The capacitance type input device is characterized in that the position information and the input information are detected from an amount of change in capacitance formed on the substrate.   The electrostatic capacitance type input device according to claim 1, wherein the reversing member is formed of a dome-shaped metal contact, and a surface of the metal contact and a surface of the counter electrode are covered with an insulating layer having a dielectric constant. .   The detection circuit includes a signal generator that outputs a pulsed input signal having a predetermined frequency, an integrator to which the input signal is applied, and a response signal that is an output of the input signal and the integrator. The capacitance-type input device according to claim 1, further comprising: a calculation unit that calculates a signal rise time; and a determination unit that determines an operation state of the electrostatic sensor from the rise time calculated by the calculation unit. .   4. The electrostatic capacitance according to claim 1, wherein the integrator has a capacitance formed between at least one of the counter electrode, the reversing member, and the operating body, and a predetermined resistance. 5. Capacitive input device.   The detection circuit obtains a change amount of the capacitance from the previously calculated calculation data of the rise time of the electrostatic sensor and the calculation data of the rise time of the electrostatic sensor detected after that, and based on the change amount, The capacitance-type input device according to claim 1, wherein an operation state of an electrostatic sensor is determined and the input information is generated.   The determination unit has a first reference value and a second reference value, and the operation state of the electrostatic sensor is such that the amount of change in the capacitance is less than the first reference value. A non-input state is determined, a contact state is determined when the reference value is greater than or equal to the first reference value and less than or equal to the second reference value, and an input state is determined when the second reference value is exceeded. The capacitance-type input device according to claim 5.

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