WO2011036710A1

WO2011036710A1 - Touch-type input device

Info

Publication number: WO2011036710A1
Application number: PCT/JP2009/004830
Authority: WO
Inventors: 高倉潤也; 山内康晋; 杉田馨
Original assignee: 株式会社東芝
Priority date: 2009-09-24
Filing date: 2009-09-24
Publication date: 2011-03-31

Abstract

A conductive panel has a planar conductive layer, and when a user comes into contact with an input surface, an input signal is propagated. A signal generation unit generates an identification signal for identifying a plurality of users. A signal supply unit supplies the identification signal to input means used by each of the users. A control unit controls a signal generation unit so as to generate an identification signal having characteristics separable for each user if there are a plurality of users. A signal detection unit is connected to a plurality of positions of the conductive panel, and performs detection of the input signal that has propagated from the conductive panel for each of the plurality of positions. A signal separation unit, on the basis of characteristics of the identification signal, separates the input signal into components corresponding to each user. A touch position estimation unit, on the basis of electrical characteristics of the conductive layer and the amplitude of the separated signal for each of the plurality of positions, estimates a contact position on the input surface of each user that is indicated by the input signal.

Description

Touch input device

The present invention relates to a touch input device.

タッチ Touch-type input devices are widely used as an interface for intuitive coordinate input. There are various input methods such as a capacitance method, a resistive film method, a surface acoustic wave method, an optical method, and a camera method.

Among them, the capacitive touch input device senses the information on the screen position touched by the user by the change in the capacitance between the fingertip and the conductive panel. When a part of a human body such as a finger comes into contact with the conductive panel through a protective film in a state where a uniform alternating electric field is formed on the conductive panel, capacitive coupling occurs between the human body and the conductive panel. In addition, since the human body and the ground serving as the reference potential point are capacitively coupled by stray capacitance, a current flows between the ground from the electric field forming unit via the conductive panel and the human body. At this time, the ratio of each current flowing out from each electric field forming unit is determined by the resistance ratio between the position of the finger touching the conductive panel and each electric field forming unit. Accordingly, if the current value flowing out from each electric field forming unit is measured, the coordinates of the touched position can be calculated from the ratio of the currents.

Also, the operation of touching multiple points simultaneously and inputting multiple coordinates simultaneously is called multi-touch. By supporting multi-touch, the degree of freedom of input operation is increased. In addition, a plurality of users can perform operations on one input device. In order for multiple users to work simultaneously on a single touch-type input device, it is not sufficient that the touch-type input device supports multi-touch. It is necessary to identify whether the input is from a user and to associate each user with each input coordinate.

A multi-user touch system in which a plurality of users can be operated simultaneously and a plurality of input coordinates can be associated with each user has been proposed (for example, Patent Document 1). In this method, a grid-like antenna is arranged on the panel in order to detect a position on the touch surface. Each antenna is connected to a signal source and supplied with signals that can be distinguished from each other. Each user is also capacitively coupled to a receiver corresponding to the user. With the above configuration, it is possible to specify which user is touching which position on the touch surface. In this method, it is necessary to form a grid pattern on the panel. Therefore, for example, even when a transparent conductive material such as ITO (indium tin oxide) is used as the antenna material, there is a problem that the light transmittance and the refractive index cannot be made uniform on the touch surface.

There has also been proposed an information input device and method capable of making a transparent conductive film uniform on the touch surface by combining electrical signal detection for identifying a user with another coordinate detection such as an optical type. (For example, patent document 2). However, since this method uses timing information for associating the touch position coordinates with the user, there is a problem that when a plurality of users touch the touch surface almost simultaneously, they cannot be identified.

US Patent 6,498,590 JP 2000-148396 A

An object of the present invention is to provide a touch input device that can identify users even when a plurality of users touch the touch surface almost simultaneously.

In order to solve the above problems, a touch input device according to one embodiment of the present invention has a planar conductive layer, and identifies a plurality of users from a conductive panel through which an input signal propagates when the input surface is touched. A signal generation unit that generates an identification signal for the user, a signal supply unit that supplies the identification signal to each user's body, and the signal generation unit that generates the identification signal having separable characteristics for each user A control unit for controlling the detection unit, a detection unit connected to a plurality of positions of the conductive panel and detecting a detection signal including a plurality of input signals propagated from the conductive panel for each of the plurality of positions, and the identification Based on a signal characteristic, a separation unit that separates the detection signal into components corresponding to each user, an electrical characteristic of the conductive layer, and a magnitude of the separated signal for each of the plurality of positions Said Comprising an estimation unit that estimates a contact position on the input surface of the user in the power signal.

According to the input device of the present invention, a plurality of users can simultaneously perform an input operation on the touch surface, and each user can be identified.

The figure explaining the outline of the input device of 1st Embodiment. The figure which shows the input device of 1st Embodiment. The figure which shows the example of the supply signal which can be isolate | separated. Sectional drawing which shows the structure of an electroconductive panel. The figure which shows the structure of a signal detection part. The figure explaining the flow of a signal when one user performs touch input. The figure which shows the example of the shape of an equal current ratio line. The figure which shows the data structure of a coordinate table. The figure explaining the flow of a signal when a plurality of users touch-input. The figure which shows the distortion of an iso-current ratio line when a plurality of users touch-input. The figure which shows the data structure of a distortion information table. The flowchart of an initial setting process. The flowchart of the whole process in coordinate input mode. The flowchart of a signal measurement process. The figure which shows the structure of the data memorize | stored in a separation signal memory | storage part. The flowchart of a touch position coordinate initial stage estimation process of all the users. The flowchart of a touch position coordinate calculation process of each user. The flowchart of a touch position coordinate repetition estimation process. The figure which shows the data structure of an equal current ratio line function parameter table. Schematic of the signal flow at the time of touch input in Modification 2 of the first embodiment. The flowchart of the signal measurement process in the modification 2 of 1st Embodiment. The figure which shows the input device of 2nd Embodiment. The figure which shows the data structure of the distortion information table in 2nd Embodiment. The figure which shows the equivalent circuit at the time of touch input and touch non-input. The flowchart of an impedance initial measurement process. The flowchart of a signal and impedance measurement process. The flowchart of the touch position coordinate initial stage estimation process of all the users in 2nd Embodiment.

Embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the structure and process which mutually perform the same operation | movement, and the overlapping description is abbreviate | omitted.

(First embodiment)
The input device of this embodiment is a capacitive touch input device. Even when a plurality of users touch the touch surface almost simultaneously, the users can be identified. In each of the following embodiments, a case where touch input is performed by a user's finger as an input unit will be exemplified. In addition, a method using various input means such as a user input using a device such as a pen may be used.

FIG. 1 is a diagram for explaining a usage state when the input device 100 of the present embodiment is applied to a desktop type.

The central area of the input device 100 is a conductive panel 4 for inputting coordinates when the user touches. A plurality of signal detection units (not shown) are arranged around the conductive panel 4 and are connected to the conductive panel 4. The input device can be used simultaneously by multiple users. Each user carries signal supply units 5-1 and 5-2 corresponding to the user, for example, in his / her arm. The signal supply units 5-1 and 5-2 are respectively connected to corresponding signal generation units (not shown).

FIG. 2 is a diagram showing the input device of this embodiment.

The input device 100 includes a conductive panel 4 through which an input signal propagates when it touches an input surface, a signal generator 7 (1 to N) that generates an identification signal for identifying N users, and each user's A signal supply unit 5 (1 to N) for supplying an identification signal to the body, a control unit 6 for controlling the signal generation unit 7 to generate an identification signal having separable characteristics for each user, and a conductive panel 4 is connected to a plurality of positions, and a detection unit 8 (1 to M) that detects a detection signal including a plurality of input signals propagated from the conductive panel 4 at each of M positions, and based on the characteristics of the identification signal A signal separation unit 9 (1 to N) that separates the detection signal into components corresponding to each user, and a touch position estimation unit that estimates the contact position of each user on the input surface of the conductive panel 4 indicated by the input signal 13

The control unit 6 determines the characteristics (signal amplitude, frequency, phase, timing, etc.) of each signal generated for the signal generation units 7-1 to 7-N to supply to each user. Here, the signals corresponding to the respective users are determined so that they can be distinguished (separated) from each other. For example, there are signals having different frequencies as shown in FIG. 3 (a) and signals having different supply times as shown in FIG. 3 (b). Alternatively, it may be encoded into a separable code. In addition, the control unit 6 notifies the signal detection units 8-1 to 8-M and the signal separation units 9-1 to 9-M of information necessary for signal detection and signal separation.

Signal generation units 7-1 to 7-N generate amplitude, frequency, phase, and timing signals set by the control unit 6. In addition to the DDS (Direct Digital Synthesis) method, the voltage signal generated by a general signal generation method such as a VCO (Voltage Controlled Oscillator) is converted into a current signal via a VCCS (Voltage Control Current Source) circuit. Transmit from signal supply unit 5-1 to 5-N.

The signal supply units 5-1 to 5-N supply the current signals (identification signals) generated by the corresponding signal generation units 7-1 to 7-N to the user's human body. As a method for supplying a current signal to the user's human body, a wristband-like one can be connected to the user's human body or clothes, or an electrode can be provided on a chair, a desk, or a floor.

The conductive panel 4 is a touch input surface, and the user can input coordinates corresponding to the touched position by touching the conductive panel 4.
FIG. 4 is a cross-sectional view showing the structure of the conductive panel 4. It has a planar conductive layer 16 made of a conductive material such as ITO (indium tin nitride), a protective layer 15 and a base layer 17 on the surface. The user touches the protective layer 15 side and inputs coordinates. The protective layer 15 is a dielectric, and when the user touches the protective layer 15, capacitive coupling occurs between the user's human body and the conductive layer, and a current signal flows. When a plurality of users touch the conductive panel 4 at the same time, current signals corresponding to the respective users flow on the conductive panel 4 simultaneously.
The signal detectors 8-1 to 8-M are connected to the conductive panel 4 and detect signals.

FIG. 5 shows the configuration of the signal detector 8-1. The configuration of the signal detectors 8-2 to 8-M is the same as that of the signal detector 8-1 and is therefore omitted. The peripheral electrode 10 adjusts the distribution of current flowing from the conductive panel 4 to the signal detector 8-1 to 8-M. The conduction switching unit 18 is a part that determines whether or not to conduct between the peripheral electrode 10 and the current-voltage conversion circuit 19 based on a command from the control unit 6, and is configured by an analog switch, for example. The current-voltage conversion circuit 19 is a part that converts the detected current into a voltage, and is an inverting amplifier circuit configured by, for example, an OP amplifier. Therefore, when the conduction switching unit 18 is in the conduction state, the point between the conduction switching unit 18 and the current-voltage conversion circuit 19 is zero potential. Further, when the conduction switching unit 18 is in a non-conduction state, the current-voltage conversion circuit 19 and the subsequent states are in a floating state as viewed from the conductive panel 4. The voltage converted by the current-voltage conversion circuit 19 is converted into a digital signal by the A / D converter 19 and transmitted to the signal separation unit 9-1.

The signal separation units 9-1 to 9-M separate the signals detected by the corresponding signal detection units 8-1 to 8-M into signals corresponding to each user based on information from the control unit. If the signals corresponding to each user are signals of different frequencies, they are separated using general methods used for frequency separation, such as Fourier transform, autoregressive coefficient calculation, digital filter, adaptive filter, etc. The amplitude of the signal corresponding to the user can be obtained. When the signals corresponding to each user are separated by time, the amplitude of the signal observed at the time when the signal is supplied to each user is set as the amplitude of the signal corresponding to each user.

The separated signal storage unit 11 temporarily stores the amplitude of the signal corresponding to each user separated by the signal separating units 9-1 to 9-M in a RAM or the like, and uses it in the processing in the touch position estimating unit 13 described later.

The conductive panel characteristic storage unit 12 stores in advance the characteristics of the conductive panel obtained by actual measurement or simulation in a storage medium such as a hard disk, EEPROM, CD-ROM, and the processing in the touch position estimation unit 13 described later. Use in.

The touch position estimation unit 13 includes a CPU, a RAM, and the like, and for each user, based on the information stored in the separation signal storage unit 11 and the characteristics of the conductive panel 4 stored in the conductive panel

characteristic storage unit

12, 4 Estimate the coordinates of the touch position of each user on the top. Details of the method of touch position estimation will be described later.

Next, a method for estimating the touch position by the input device according to the present embodiment will be described. First, a case where one user performs touch input will be described.
In FIG. 6, the signal generated by the signal generation unit 7-1 is supplied to a certain user by the signal supply unit 5-1, and the user touches a point on the conductive panel 4 to connect to the conductive panel 4. Among the signal detection units 8-1 to 8-M, the signal flow when the signal detection units 8-1 and 8-2 are in a conductive state is schematically shown.

At this time, if the current detected by the signal detector 8-1 is I1 · 1-2, and the current detected by the signal detector 8-2 is I2 · 1-2, then I1 · 1 When the ratio of -2 and I2 · 1-2 is a certain value, the user's touch position is on a curve (hereinafter referred to as an iso-current ratio line) that passes between the signal detectors 8-1 and 8-2. You can see that
Subsequently, as another combination of signal detection units, for example, if signal detection is performed with the signal detection units 8_1 and 8_M in a conductive state, the touch position passes between the signal detection units 8_1 and 8_M, and an equal current It can be seen that it exists on the ratio line. Therefore, the intersection of the isocurrent ratio line obtained with the signal detectors 8-1 and 8-2 in the conductive state and the isocurrent ratio line obtained with the signal detectors 8_1 and 8_M in the conductive state is the touch position to be obtained. Coordinates.

FIG. 7A shows an isocurrent ratio line obtained when the signal detection units 8_1 and 8-2 are in a conductive state, and FIG. 10 shows an isocurrent ratio line obtained when the signal detection units 8_1 and 8-M are in a conductive state. The numerical values attached to the curves in the figure are log (I1 · 1-2 / I2 · 1-2) in FIG. 7 (a) and log (I1 · 1-M / in FIG. 7 (b). IM · 1-M). If the pair of signal detectors arranged diagonally is in a conductive state, the isocurrent ratio line can be made closer to a straight line by devising the resistance value of the peripheral electrode 10 (Patent No. 1). 4168537), and other combinations of signal detectors, the isoelectric ratio curve is curved. Here, including a method for dealing with a curved iso-current ratio line, coordinates are estimated using the iso-current ratio line shown in FIGS. 7A and 7B when the resistance value of the peripheral electrode 10 is infinite. A method will be described.

If u = log (I1 ・ 1-2 / I2 ・ 1-2) and v = log (I1 ・ 1-M / IM ・ 1−M), the coordinates of the touch position are the isocurrent ratio line corresponding to u. It is uniquely determined by finding the intersection of isocurrent ratio lines corresponding to v. Therefore, based on measured or simulated values, discrete ui (i = 1,2, ..., ui <ui + 1) and vj (j = 1,2, ..., vj <vj + 1) values It is possible to have a table having a structure as shown in FIG. The X coordinate and Y coordinate corresponding to ui and vj in the table corresponding to the combination of the signal detection unit pairs being used are expressed as X (ui, vj) and Y (ui, vj), respectively. Assuming that the actually measured values are u and v, and ui <u <ui + 1 and vj <v <vj + 1, the coordinates X and Y of the touch position are approximated by

Equations

1 and 2, respectively. be able to.

Here, w1 to w4 are determined according to the difference from the values of u and v, for example, by the following equations.

If ui and vj satisfying u = ui and v = vj exist, X (ui, vj) and Y (ui, vj) can be directly used as the coordinate estimation value of the touch position.
Here, a diagram in which each signal detection unit is arranged in four corners of the touch panel is used, but the signal detection units are not necessarily arranged in four corners, and the number thereof may be four or more. Further, the combination of signal detection unit pairs to be used is not limited to 8_1 and 8-2, and 8_1 and 8-M, and any combination can be used.

Next, the principle of touch position coordinate estimation when a plurality of users perform touch input simultaneously will be described.
In FIG. 9, the signal generated by the signal generation unit 7-1 is supplied to a user via the signal supply unit 5-1, and the signal generated by the signal generation unit 7-2 is supplied to the signal supply unit 5- 2 is a schematic representation of the flow of signals supplied to another user via 2 and each user touching a point on the conductive panel at the same time. At this time, since the signal generation unit 7-1 supplies a signal as a current source to the user, the signal from the signal generation unit 7-2 does not flow into the signal generation unit 7-1. The signal from the signal generator 7-1 does not flow into the signal generator 7-2. However, a part of the signal from the signal generator 7-2 flows to the ground via the ground stray capacitance 21, and a part of the signal from the signal generator 7-1 flows to the ground via the ground stray capacitance 22. To do.

The signals detected by the signal detection units 8_1 and 8_M are a mixture of the signal from the signal generation unit 7-1 and the signal from the signal generation unit 7-2. -1 and 9-M can be separated into signals corresponding to each user. If the influence of the signal flowing out to earth via ground floating capacitance can be ignored, using the signal corresponding to each separated user, as in the case where one user mentioned above performs touch input, The coordinates of the touch position corresponding to each user can be obtained.

However, in reality, the influence of the signal flowing from the ground floating capacity to the ground cannot be ignored. FIG. 10 shows the shape of the equicurrent ratio line when a signal flows out from the point 24 on the conductive panel 4 to the ground. As described above, it is known that the shape is distorted as compared with FIG. 7B showing the isocurrent ratio line when it is assumed that there is no outflow. Therefore, when a plurality of users perform touch input at the same time, an error may occur in the estimation of the touch position.

By the way, comparing FIG. 7B and FIG. 10, it can be seen that there are portions where the distortion of the isocurrent ratio line is large and portions where it is not. That is, there are areas where the estimation error of the touch position coordinates is large and areas where the estimation error is not, and the direction of the shift is different in each area. Whether or not this estimation error is relatively large depends on the touch position coordinates of the touch input of the user to be estimated, the touch position coordinates of the touch input other than the user to be estimated, and the positional relationship of the signal detection unit pair. Determined.

When the touch position of the touch input other than the user to be estimated is at the point (x ', y'), the amount EX (x, 'where the isocurrent ratio line is shifted in the X direction and the Y direction at the point (x, y) y ', x, y) and EY (x', y ', x, y) are determined by determining the value of impedance ZL from the conductive panel to the ground through the human body other than the user to be estimated. The signal detection unit pair can be obtained by actual measurement or simulation. The value varies depending on the value of ZL, but the relative magnitude relationship is constant regardless of ZL. If each coordinate position is a discrete value, a table having a structure as shown in FIG. 11 can be obtained.

When x'k <x '<x'k + 1, y'l <y'<y'l + 1, xm <x <xm + 1, yn <y <yn + 1, EX and EY are Each can be approximated by, for example:

However,

This value is obtained for each signal detector pair.

In addition, in order to obtain the total distortion of a plurality of users, the distortion is obtained by

Equations

7 and 8 for each user, and the total is simply obtained for all users, whereby the maximum likelihood estimate of the distortion in this case Can be requested.

In order to estimate the coordinates of the touch position on the conductive panel which is a two-dimensional plane, it is only necessary to have signal measurement results from at least two signal detection unit pairs among the signal detection unit pairs. Therefore, of the measurement results of all available signal detection unit pairs, when estimating the X coordinate, the signal detection unit pair with a small absolute value of EX is used, and when estimating the Y coordinate, the absolute value of EY is used. If at least two signal detection unit pairs each having a small signal size are selected and the touch position coordinates are estimated based on the measurement results, estimation errors due to simultaneous touching by a plurality of users can be reduced.

As described above, whether or not the estimation error of the touch position coordinate estimated using a certain signal detection unit pair is large depends on the touch position coordinate of the touch input of the user to be estimated and the touch input other than the user to be estimated. The touch position coordinates and the signal detection unit pair. That is, if the touch position coordinates of the touch input of the user to be estimated and the touch position coordinates of the touch input other than the user to be estimated are known, an optimal signal detection unit pair can be selected. However, if the optimum signal detection unit pair cannot be selected, the touch position coordinates of the touch input of the user to be estimated and the touch position coordinates of touch inputs other than the user to be estimated cannot be obtained accurately. That is, this problem is an incomplete problem that lacks information (parameters) necessary to solve the problem.

In this way, the parameters necessary to solve the problem are not found, but the parameters required to solve the problem are statistically determined by the EM algorithm as a method for solving the problem that can be obtained by solving the problem. Used in academic fields. (Non-patent literature: Arthur Dempster, Nan Laird, and Donald Rubin. "Maximum likelihood from incomplete data via the EM algorithm". Journal of the Royal Statistical Society, Series B, 39 (1): 1-38, The concept of the algorithm is summarized as follows. When a parameter necessary for solving a problem is insufficient, the problem is solved by assuming an arbitrary value for the parameter, and the parameter is obtained. If the problem is solved again using the parameters obtained in this way, the parameters obtained at that time will be more accurate than the previously obtained parameters. By repeating this procedure, it is assured that the parameter estimates converge to a locally optimal solution. However, whether or not to converge to the global optimal solution depends on the initial value of the assumed parameter.

This concept is used for the touch position estimation method in the embodiment. That is, when estimating the respective touch positions when a plurality of users are performing touch input at the same time, assuming a certain touch position coordinate, the optimum signal detection unit set is selected and the touch position coordinate is re-established. Make an estimate. Assuming the touch position coordinates thus obtained, the touch position coordinates are re-estimated again, thereby bringing the estimated value of the touch position coordinates closer to the optimum touch position coordinate estimated value. At this time, in order for the estimated value of the touch position coordinates to converge to the optimum touch position coordinate estimated value, the initial value of the parameter (initial value of the initial touch position coordinate) is changed to the actual coordinate of the touch position. It is necessary to be close. As the initial value of the assumed touch position coordinates, for example, the touch position coordinates obtained on the assumption that there is no signal interference can be used.

Based on the above configuration and principle, the operation of the apparatus for estimating the coordinates of the input position will be described in detail based on the flowcharts of FIGS.
First, when the power of the present apparatus is turned on, the initial setting mode is set, and the control unit 6 performs an initial setting process.
FIG. 12 is a flowchart when performing the initial setting process. In step S1, the control unit 6 sets all the signal generation units 7 so as not to perform signal generation.
In step S2, each signal detector 8 detects a signal. As for the signal detected here, noise is detected because the signal generator 7 does not generate a signal.
In step S3, the signal detected in step S2 is separated by the signal separation unit 9 into each frequency included in a plurality of different frequency combination candidates, and the magnitude of each signal is stored in the separated signal storage unit 11. The frequency combination is a combination of frequencies assigned to each user, and frequencies for the maximum number of users that are set so as not to be an integral multiple of each other are prepared. A plurality of frequency combination candidates are prepared in the control unit 6, and the combination selected by the control unit 6 is notified to the signal separation unit 9.

In step S4, in order to determine whether or not the frequency combination use candidate assigned to each user can be used in the control unit 6, the signal of each frequency stored in the separated signal storage unit 11 in step S3. Set the initial value of the threshold for comparison with the size.

In step S5, the control unit 6 makes a determination with reference to a determined flag for determining whether or not a frequency combination that has not been determined to be usable among a plurality of frequency combination candidates has been determined. Set as a candidate.

Step S6 is a step in which the control unit 6 determines whether the frequency combination set in Step S5 is usable. If the maximum number of users is N, there are N frequencies in the frequency combination to be determined whether it can be used. Of the magnitudes of the signals stored in step S3, the control section 6 reads the magnitude of the signal corresponding to each frequency of the frequency combination to be determined from the separated signal storage section 11, and is set in step S4 or S8. Compare with the threshold value. If the signal magnitude is smaller than the threshold value at all frequencies, it is determined that the frequency combination can be used, and the process proceeds to step S7.

If any one of the signals included in the frequency combination is greater than the threshold, the control unit 6 determines that the frequency combination is unusable and sets the determined flag of the determined frequency combination to determined. The process proceeds to step S8.

In step S7, the control unit 6 refers to the determined flag and determines whether determination has been performed for all frequency combination candidates. If all the frequency combination candidates have been determined, the determined flag is cleared and the process proceeds to step S8. If there is an undetermined frequency combination, the process proceeds to step S5.
Step S8 loosens the determination criteria when it is determined that all frequency candidates are unusable. That is, the threshold value set in the control unit 6 is set larger than the previous threshold value.
In step S9, each frequency of the frequency combination determined in step S5 is set by the control unit 6 for each signal generation unit 7 and signal separation unit 9. Upon receiving this notification, each signal generation unit 7 starts signal generation, and the signal separation unit 9 thereafter performs signal separation assuming that each set frequency is a signal corresponding to each user.
After the above initial setting process is completed, the initial setting mode is shifted to the coordinate input mode. In the coordinate input mode, processing for estimating touch input position coordinates described below is performed at regular intervals.

FIG. 13 is a flowchart showing the entire processing in the coordinate input mode. In step A1, measurement of signals necessary for touch position coordinate estimation is performed. Subsequently, in step A2, each input position coordinate of each user is estimated. Here, the touch position coordinates are estimated on the assumption that the touch inputs of the respective users do not interfere with each other. The touch position coordinates estimated here include an error when a plurality of users perform touch input simultaneously. Step A3 is a step in which the process is branched depending on whether a plurality of users are performing touch input. If a plurality of users are making touch input, the process proceeds to step A4, and if not, the process proceeds to step A5. Step A5 reports the estimated touch position coordinates. Details of processing contents in A1, A2, A3, and A4 will be described in detail below.

FIG. 14 is a flowchart showing the processing content of step A1 in FIG. In Step M1, signal generation is started in each of the signal generation units 7-1 to 7-N, and a signal is supplied to the user via the signal supply units 5-1 to 5-N.
In step M2, the signal detection unit 8 that performs signal detection is selected. From the pair of signal detectors 8 that have not been measured, the control unit 6 selects a pair of signal detectors 8 that perform signal detection. Then, the pair of the signal detection units 8 is set to a conductive state.
In step M3, each pair of signal detection units 8 selected by the control unit 6 in step M2 detects signals.
In step M4, the signal detected by the signal detection unit 8 in the immediately preceding step M3 is separated into signals corresponding to each user in the signal separation unit 9. In addition, the magnitude of the signal corresponding to each user output from the signal separation unit 9 is stored in the separation signal storage unit 11.

Step M5 is a step for determining whether or not measurement has been performed for all pairs of signal detection units 8 used by the control unit 6. If measurement has been performed for all pairs of signal detection units 8 to be used, go to Step M6. move on. If there is an unmeasured pair among the pairs of signal detectors 8 to be used, the process proceeds to step M2.

In step M6, upon receiving a notification from the control unit 6, the signal generation unit 7 stops signal generation and ends signal supply to the user. At the time when the processing from M1 to M6 is completed, the separated signal storage unit 11 stores the magnitude of the signal corresponding to each user measured in each pair of signal detection units 8 as shown in FIG. Information is stored.

Subsequently, the process of step A2 in FIG. 13 will be described. FIG. 16 is a flowchart showing the process of step A2 in FIG. The following steps E1 to E4 are executed by the touch position estimation unit 13.

First, in step E1, the user who estimates the touch position coordinates is determined.

Step E2 is a step of determining whether or not the user is performing touch input. The magnitude of the signal corresponding to the user stored in the separated signal storage unit 11 is read, and if the maximum value is equal to or greater than a preset threshold value, it is determined that the user is making a touch input. If it is determined that touch input is being performed, the process proceeds to step E3. If it is determined that touch input is not performed, the process proceeds to step E1.

Step E3 is a process of performing touch position coordinate estimation corresponding to the user who is determined to be performing touch input in Step E2. Details of the processing here will be described later with reference to the flowchart of FIG.

Step E4 is a step of determining whether or not the touch position coordinates have been estimated for all the users who are making touch input. If the estimation of the touch position coordinates of all users who have performed touch input has been completed, the process ends. If there is a user whose touch position coordinates have not been estimated, the process proceeds to step E1.

Next, the process in step E3 of FIG. 16 will be described using the flowchart shown in FIG. In step C1, the pair combination of the signal detection unit 8 used for coordinate estimation is selected from the combination of pairs to be used for which coordinate estimation has not been performed.

In step C2, in each of the pair of signal detection units 8 selected in step C1, the magnitude of the signal corresponding to the user who performs touch position coordinate estimation is read from the separated signal storage unit 11, and the ratio is read for each signal detection unit 8 For a pair of.

In step C3, the coordinates corresponding to the ratio of the signal magnitudes calculated in step C2 are calculated by referring to the coordinate table stored in the conductive panel characteristic storage unit 12, using the

formulas

1 and 2, and the signals The coordinates are stored as a combination of a pair of detection units 8.

Step C4 is a step in which it is determined whether coordinate calculation has been performed for all combinations of pairs of signal detection units 8. If coordinate calculation has been completed for all pair combinations, the process proceeds to step C5. If there is a pair combination for which coordinates have not been calculated, the process proceeds to step C1.

Step C5 calculates an average value of coordinates calculated by the combination of each signal detection unit pair, and uses it as an estimated value of the touch position coordinates.

Subsequently, the process in step A4 in FIG. 13 will be described with reference to the flowchart in FIG. The following processing from R1 to R11 is executed by the touch position estimation unit 13. In step R1, the touch position coordinates of each user already estimated in step A3 are set to the initial values of the touch position coordinate estimated values.

In step R2, the user who estimates the touch position coordinates is set.
In step R3, a pair of signal detectors 8 for calculating the distortion of the equal current ratio line is selected.
In step R4, the initial estimated value of the touch position coordinates of the user who estimates the touch position coordinates and the distortion of the isocurrent ratio line of the signal detection unit pair corresponding to the initial estimated position of the touch position coordinates other than the user are expressed by Equation 7: And is calculated by Equation 8 and stored as a distortion of the equal current ratio line in the signal detection unit pair.
In step R5, for the user set in step R2, it is determined whether or not the equicurrent ratio line distortion has been calculated for each pair of signal detectors 8. If the equivalent current ratio distortion has been calculated for each pair of signal detectors 8 for the user, the process proceeds to step R6. If there is a pair for which the distortion of the isocurrent ratio line has not been calculated, the process proceeds to step R3.
In step R6, the values of the isocurrent ratio line distortion values calculated in step R4 are compared for each pair of signal detectors 8, and the pair of signal detectors 8 having a smaller value is used for estimating the touch position coordinates of the user. Select as a pair.

In step R7, the user's touch position coordinates are re-estimated using the pair of signal detection units 8 selected in step R6. The details of the processing here are the same as the processing in step E3 in FIG. 16, and are shown in the flowchart in FIG. However, the pair combination of the signal detection unit 8 to be used is the combination of the pair selected in step R6.

Step R8 is a step of determining whether or not the re-estimation of the touch position coordinates assuming the touch position coordinates set in the immediately preceding step R1 or R11 has been performed for all the users performing touch input. If re-estimation has been completed for all users, the process proceeds to step R9. If there is a user for which re-estimation has not been performed, the process proceeds to step R2.

Step R9 is a step of determining whether or not the re-estimation process has converged. Calculate the difference between the initial value of the touch position coordinate set in the previous step R1 or R11 and the re-estimated value of the touch position coordinate re-estimated assuming that initial value, and the difference is less than or equal to the preset threshold value. For example, it is determined that the re-estimation process has converged. If it is determined that the re-estimation process has converged, the step re-estimation process ends. If it is determined that it has not converged, the process proceeds to step R10.
Step R10 is a step of determining whether or not the maximum estimated number of iterations has reached a specified number. If the maximum number of iterations reaches the specified number, the re-estimation process is terminated even if the maximum estimation process has not converged. If the specified number of times has not been reached, the process proceeds to step R11.
Step R11 replaces the initial value for re-estimating the touch position coordinates with the estimated touch position coordinates.
In this embodiment, even in a touch input device with a uniform light refractive index and transmittance, the touch input surface allows a plurality of users to perform touch input at the same time, and the signal is less affected by interference. By estimating the touch position using the detection unit, it is possible to reduce errors due to signal interference caused by simultaneous input by a plurality of users.

(Modification 1 of the first embodiment)
Modification 1 of the first embodiment will be described. The shape of the iso-current ratio line is a complex curve and is difficult to express with a single function. However, it is possible to approximate the shape of the isocurrent ratio line by a function that can be expressed by a small number of parameters. When a pair of signal detectors 8-1 and 8-M is used, if the ratio of the respective current magnitudes is u = log (I1 · 1-M / IM · 1-M), the following is an example: Approximation is possible.

Also, when a pair of signal detectors 8-1 and 8-2 is used, if the ratio of the current magnitude of each signal detector v = log (I1 · 1-2 / I2 · 1-2),

Various other approximate expressions can be used depending on the position of the pair of signal detectors 8.

For each signal detection unit pair, a parameter at a certain current magnitude ratio can be obtained by actual measurement or simulation, and can be stored as a table having a structure as shown in FIG. The function of u = ui is y = Fui (x), the function of v = vj is y = Fvj (x), the actually measured values are u and v, and ui <u <ui + 1, vj <v <Vj + 1, for example

By obtaining the intersection point, the coordinates of the touch position can be obtained. However,

It is. In the present modification, the touch position coordinates can be obtained by obtaining the intersection of Equation 18 and Equation 19 instead of Equation 1 and Equation 2.
In this modification, the amount of data to be stored in the conductive panel characteristic storage unit 12 can be reduced.

(Modification 2 of the first embodiment)
A second modification of the first embodiment will be described.
FIG. 20 shows a case where the user performs touch input and the signal detection units 8-1, 8-2, 8-3, and 8-M arranged at the four corners of the conductive panel are in a conductive state. It is the figure which represented the flow of the signal typically. This shows that the signal flow is only reversed as compared to the signal flow on a normal capacitive touch panel.

Therefore, when the magnitude of the signal detected by each signal detection unit is I1, I2, I3, IM = I4, the X coordinate and Y coordinate are the following formulas as in the normal capacitive touch panel: Can be obtained.

Even when a plurality of users perform touch input at the same time, the touch position coordinates of each user can be estimated by Expression 23 and Expression 24 after being separated into signals corresponding to each user. When a plurality of users perform touch input, an error occurs in the estimated position of the touch position coordinates, but it can be used for applications where accuracy is not required.

In this modification, the signal measurement process shown in the flowchart of FIG. 13 is replaced with the flowchart of FIG. The contents of steps Q2 and Q3, which are processing different from the processing in FIG. 13, in the signal measurement processing in this modification shown in FIG. 21 will be described.

In step Q2, the signal detection units 7-1 to 7-M arranged at the four corners of the conductive panel 4 are turned on by notification from the control unit 6, and signals are detected in the respective signal detection units 7. .

In step Q3, the signal detected in the signal detection unit 7 in the immediately preceding step Q2 is separated into signals corresponding to each user by the signal separation unit 9, and the respective magnitudes are stored in the separation signal storage unit 11.

In addition, in the coordinate calculation, the touch position coordinates can be calculated by Expression 23 and Expression 24 instead of Expression 7 and Expression 8. However, iterative estimation of touch position coordinates is not performed regardless of whether a plurality of users are touching.

According to this modified example, when the influence of interference caused by a plurality of users performing touch input at the same time can be ignored, the touch position coordinates can be estimated by simple processing.

(Second Embodiment)
FIG. 22 shows a block diagram of a system in the second embodiment. Description of parts similar to those in FIG. 2 is omitted.
The impedance measuring units 23-1 to 23-N detect the voltage at each of the signal supply units 5-1 to 5-N, and measure the ground impedance of the connected user. The impedance measured here is used for touch position estimation in the touch position estimation unit 13. Details of the touch position estimation method will be described later.
Next, the principle of the touch position estimation method in this embodiment will be described. The method of initial estimation of the touch position coordinates is the same as that of the second modification of the first embodiment. That is, first, the touch position coordinates of each user are estimated from Expression 23 and Expression 24 from the magnitude of the signal corresponding to each user in the signal detectors arranged at the four corners of the conductive panel 4.

∙ When multiple users are performing touch input at the same time, an error occurs in the touch position. When the touch position of the user who is trying to estimate the coordinates of the touch position is x, y and the coordinates of the touch position other than the user who is to be estimated are (x ', y'), the user other than the user who is trying to estimate If the impedance ZL from the conductive panel through the human body to the ground is determined, the amount of deviation in the x direction, y direction, EX (x, 'y', x, y) and EY (x ', y ′, x, y) can be obtained by actual measurement or simulation. Moreover, if each is made into a discrete value, the value calculated | required beforehand can be made into the table of a structure as shown in FIG.

When x'k <x '<x'k + 1, y'l <y' <y'l + 1, xm <x <xm + 1, yn <y <yn + 1, EX (x, 'Y', x, y) and EY (x ', y', x, y) can be approximated by equations similar to

Equations

7 and 8, for example.

If the table referred to when calculating Equation 7 and Equation 8 is a value obtained assuming ZL = ZL0, and the ground impedance other than the actual user to be estimated is ZL, then Equation 7 and Equation 8 The obtained EX and EY times 1 / ZL are approximate values of the actual deviation. That is, the touch position coordinates x and y of the touch input of the user to be estimated, the touch position coordinates x ′ and y ′ of the touch input other than the user to be estimated, and the ground impedance ZL other than the user to be estimated are If it is known, the estimated shift of the touch position coordinate can be corrected. If the coordinates obtained by Equation 23 and Equation 24 are X and Y,

Can be corrected.

In addition, when there are a plurality of users other than the user to be estimated, the amount of deviation by each user can be obtained and the total calculated.

Next, a method for measuring the ground impedance ZL of each user will be described with reference to FIG. 23 and FIG. FIG. 24A shows an equivalent circuit when a user who has received a signal from the signal generation unit 7-1 performs touch input on the touch panel. ZE represents the impedance from the user to the ground, ZT represents the impedance between the conductive panel and the user, and ZP represents the impedance of the conductive panel. At this time, the voltage measured by the impedance measuring unit 23-1 is defined as VT. On the other hand, FIG. 24B shows an equivalent circuit in the case where the user who receives the signal from the signal generation unit 7-1 does not perform touch input on the touch panel. At this time, when the voltage measured by the impedance measuring unit 23-1 is VNT, the following equations are established.

In addition, regarding Equation 28, if ZT >> ZP, the following approximation holds.

Actually, for example, when the resistance value of the conductive panel is 1 kΩ / □ and the signal frequency is about 100 kHz or less, the approximation of Equation 29 is well established. Since ZL to be obtained is ZT + ZE, it can be obtained by Equation 30 obtained by solving Equation 27 and Equation 29.

In addition to this, if the touch position coordinates of the touch input of the user to be estimated and the touch position coordinates of the touch input other than the user to be estimated are known, the deviation amount of the touch position coordinate estimated value is expressed by Expression 25 and Expression 26. Can be corrected. However, if the deviation amount of the estimated value cannot be obtained, the touch position coordinates of the touch input of the user to be estimated and the touch position coordinates of the touch input other than the user to be estimated cannot be accurately determined. That is, as in the case of the first embodiment, it is an incomplete problem in which parameters necessary for solving the problem are insufficient.

Again, this problem can be dealt with in the same way as in the first embodiment. That is, when correcting each touch position when a plurality of users are simultaneously performing touch input, assuming a certain touch position coordinate, a correction amount is calculated to correct the touch position coordinate. By assuming the touch position coordinates thus obtained and correcting the touch position coordinates again, the estimated value of the touch position coordinates can be brought closer to the optimum touch position coordinate estimated value.

Based on the above configuration and principle, the operation of the apparatus for estimating the coordinates of the input position will be described in detail based on the flowcharts of FIGS.

FIG. 25 is a flowchart showing the flow of initial impedance value measurement processing. This process is executed during the transition from the initial setting mode to the coordinate input mode. Step Z1 sets all the signal detection units to the non-conduction state.
In step Z2, the control unit 6 sets a user who measures impedance (voltage in the user's signal supply unit) from among users whose impedance has not been measured.
In step Z3, the control unit 6 notifies the signal generation unit 7 corresponding to the user set in step Z2 to start signal generation. In response to this, the corresponding signal generation unit 7 starts signal generation, and a signal is supplied to the corresponding user.
In step Z4, the impedance measurement unit 23 measures the impedance (the voltage at the user's signal supply unit of the user), and stores it in the touch position estimation unit 13 as a VN corresponding to the user.
In step Z5, the signal generator 7 terminates signal generation for the user in response to a notification from the controller 6.
In step Z6, the control unit 6 determines whether or not impedance measurement has been performed for all users. If there is a user whose impedance has not been measured, the process proceeds to step Z2. Otherwise, the process ends.
Next, the signal and impedance measurement process in the present embodiment will be described. FIG. 26 is a flowchart of signal and impedance measurement processing. This process replaces the signal measurement process in the second modification of the first embodiment shown in FIG. 21, and the processes other than step P2 are the same as the processes described above, and thus the description thereof is omitted.
In step P2, the impedance measurement unit 23 measures the impedance (voltage in the signal supply unit) of each user, and stores it in the touch position estimation unit 13 as the voltage in the signal supply unit corresponding to each user. However, at this time, it is unknown whether the voltage corresponds to VT or VNT.

Next, the initial estimation process in this embodiment will be described with reference to the flowchart of FIG. Since the processes other than steps F3 and F4 are the same as the above processes, description thereof will be omitted. Further, the following processing is executed in the touch position estimation unit 13.

Step F3 is executed when it is determined that the user set in Step F1 does not perform touch input in Step F2. At this time, the voltage corresponding to the user measured in the immediately preceding step P2 is set as the value of VNT corresponding to the user.

Step F4 is executed when it is determined that the user set in Step F1 is performing touch input in Step F2. At this time, the voltage corresponding to the user measured in the immediately preceding step P2 is set as the value of VT corresponding to the user.

Further, in the touch position coordinate estimation process and the re-estimation process,

Expressions

25 and 26 are used.

In this embodiment, by measuring the impedance to the ground from the touch position of each user, it is possible to correct an error due to signal interference caused by a plurality of users inputting simultaneously.

1 ... Electric field forming part
2 ... Conductive panel
3 ... Current detector
4 ... Conductive panel
5-1、5-2、5-N ・・・ Signal supply unit
6 ... Control unit
7-1, 7-2, 7-N ... Signal generator
8-1, 8-2, 8-M ... Signal detector
9-1, 9-2, 9-M ... Signal separator
10 ... Peripheral electrode
11 ... Separated signal storage
12 ... Conductive panel characteristic memory
13 ... Touch position estimation unit
15 ... Protective layer
16 ... conductive layer
17 ... Substrate layer
18 ... Conductivity switching part
19 ... Current-voltage conversion circuit
20 ... A / D converter
21 ・・・ Ground capacity of user connected to 7-1
22 ・・・ Ground capacitance of user connected to 7-2
23-1, 23-2, 23-N ・・・ Impedance measurement unit
24 ... Signal outflow point on conductive panel
25 ・・・ Impedance between user and ground
26: Impedance between user and conductive panel
27 ... Impedance of conductive panel

Claims

A conductive panel that has a planar conductive layer and propagates an input signal when in contact with the input surface;
A signal generator for generating an identification signal for identifying a plurality of users;
A signal supply unit for supplying an identification signal to the input means used by each user;
A control unit that controls the signal generation unit to generate the identification signal having separable characteristics for each user;
A detection unit connected to a plurality of positions of the conductive panel and detecting a detection signal including a plurality of input signals propagated from the conductive panel for each of the plurality of positions;
A separation unit that separates the detection signal into components corresponding to the users based on the characteristics of the identification signal;
An estimation unit that estimates a contact position on the input surface of each user indicated by the input signal based on electrical characteristics of the conductive layer and a magnitude of the separated signal for each of the plurality of positions;
A touch-type input device comprising:
It further includes a measurement unit that measures the impedance from the contact position of the user to the ground,
The touch-type input device according to claim 1, wherein the estimation unit further estimates the contact position using the impedance.
The detection unit is disposed at three or more positions of the conductive panel, and can control whether or not to conduct the input signal at each position,
The touch input device according to claim 2, wherein the control unit selects the detection units at two positions and performs control so that the input signal is conducted in the selected detection units.
For each characteristic of the identification signal, estimation is made on error information indicating the magnitude of the error in the estimation result of the contact position when the identification signal is supplied and the contact position on the input surface is touched. A storage unit for storing each detection unit set used in
The control unit selects a combination of the detection units at two positions used when the estimation unit estimates the contact position based on the user's estimated contact position and the error information. The touch input device according to claim 3.
The control unit controls the signal generation unit to generate the identification signal having a frequency different from each other and different from each other as the identification signal having separable characteristics for each user. The touch input device according to claim 3.
The said control part is controlled to make the said signal generation part generate | occur | produce the said identification signal isolate | separated in time as the said identification signal which has the characteristic which can be separated for every user. Touch input device.
The control unit controls the signal generation unit to generate the identification signal encoded in a code that can be separated from each other as the identification signal having a separable characteristic for each user. Item 4. The touch input device according to item 3.