Position detector, integrated circuit, and position detection method

Abstract

The invention provides a position detector, an integrated circuit, and a position detection method. Amplitude attenuation of a pen signal obtained from a circuit of a position indicator is suppressed. The present invention is provided with: a coil (104) configured so as to function as a sensor and including a transmission coil (104a) that transmits an alternating magnetic field based on a TX signal (transmission signal) to a position indicator (2); and a signal processing circuit (102) which is connected to the coil (104), detects an RX signal (pen signal) generated by the position indicator (2), generates a TX signal having a frequency based on frequency information of the detected RX signal, and transmits the TX signal to the transmission coil (104a).

Description

Technical Field

[0001] The invention relates to a position detector, an integrated circuit and a position detection method. Background Art

[0002] In recent years, input devices other than a mouse and the like have been used as input devices for personal computers, tablet terminals, and the like.

[0003] Such an input device is composed of, for example, a position indicator formed in a pen shape and a position detection device having an input area for performing pointing operations, inputting characters, images, and the like using the position indicator.

[0004] The position indicator is also provided with a circuit for detecting pen pressure.

[0005] A circuit for detecting writing pressure in a position indicator, as described in Patent Document 1, for example, has a structure in which a variable capacitance capacitor is connected in parallel to a resonant capacitor in a resonant circuit constituted of a position indicating coil and a resonant capacitor.

[0006] The variable capacitance capacitor is formed of a rod-shaped member and is attached to the other end of a core body whose one end serves as a pointing portion having a function as a pen tip.

[0007] The circuit for detecting the writing pressure in the position indicator utilizes the characteristics of a variable capacitance capacitor whose capacitance value changes when writing pressure is applied to the indicating portion, and outputs the change in writing pressure as a change in resonance frequency output from the circuit.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent No. 5534419 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The position detection device detects a change in the resonance frequency output from the circuit of the position indicator as a phase difference.

[0013] Therefore, in previous position detection devices, the pen pressure of the position indicator could not be detected only by a signal generator consisting of an oscillator and a current driver that generate a transmission signal of a predetermined single frequency, and a synchronous detection circuit that detects the change in frequency of a pen signal supplied from the oscillator and detected using a signal of that frequency relative to the transmission signal as a phase change.

[0014] Here, when no pen pressure is applied to the indicating part of the position indicator, if the resonant frequency output from the circuit of the position indicator is made consistent with the single frequency generated in the position detection device, a pen signal with a large amplitude can be obtained from the circuit of the position indicator (refer to Figures 14 and 15 (B)).

[0015] However, if pen pressure is applied to the indicating portion of the position indicator and the resonant frequency of the pen signal output from the circuit of the position indicator changes, the resonant frequency output from the circuit of the position indicator and the single frequency generated in the position detection device will be inconsistent (see Figure 15(A)).

[0016] That is, when a pen pressure is applied to the pointing portion of the position pointer, a phenomenon occurs in which the amplitude of a pen signal obtained from the circuit of the position pointer is attenuated (see FIG. 15(B) ).

[0017] In addition, after the position detector generates a single-frequency send signal for a certain period of time (the "TX period" in Figure 15(B)), it detects the resonant frequency of the pen signal output from the circuit of the position indicator during the period when the generation of the single-frequency send signal is stopped (the "RX period" in Figure 15(B)).

[0018] Therefore, when the resonant frequency detection process of the pen signal is performed in the position detector, the resonant frequency detection process of the pen signal is performed in a state where the attenuation degree of the amplitude of the pen signal is further increased.

[0019] As described above, in the technology described in Patent Document 1, etc., when pen pressure is applied to the indicating portion of the position indicator, the amplitude of the pen signal obtained from the circuit of the position indicator attenuates, thereby reducing the S / N ratio of the pen signal obtained from the circuit of the position indicator, which may lead to a decrease in the position detection accuracy of the position indicator and a decrease in the detection accuracy of the pen pressure.

[0020] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a position detector, an integrated circuit, and a position detection method that suppress attenuation of the amplitude of a pen signal obtained from a circuit of a position indicator.

[0021] Means for solving problems

[0022] Method 1: One or more embodiments of the present invention propose a position detector, comprising: a coil, configured to function as a sensor, including a sending coil that sends an alternating magnetic field based on a sending signal to a position indicator; a signal processing circuit, connected to the coil, detecting a pen signal generated by the position indicator, and generating the sending signal having a frequency based on the frequency information of the detected pen signal and sending it to the sending coil.

[0023] Method 2: One or more embodiments of the present invention provide an integrated circuit for detecting a position indicated by a position indicator, wherein the integrated circuit is connected to a coil, and the coil is configured to enable multiple electrodes to function as a sensor, including a sending coil that sends an alternating magnetic field based on a sending signal to the position indicator, the integrated circuit detects a pen signal generated by the position indicator, and generates a sending signal having a frequency based on the frequency information of the detected pen signal, and sends an alternating magnetic field to the position indicator via the coil.

[0024] Method 3: One or more embodiments of the present invention propose a position detection method, which is a position detection method in a position detector, wherein the method comprises: a first step, in which the position detector sends a first signal to a position indicator; a second step, in which the position indicator sends a second signal to the position detector; a third step, in which the position detector detects frequency information from the second signal; a fourth step, in which the position detector generates a third signal having a frequency different from that of the first signal based on the frequency information detected in the third step; and a fifth step, in which the position detector sends the third signal generated in the fourth step to the position indicator.

[0025] Method 4: One or more embodiments of the present invention propose a position detector, comprising: a detection coil, configured to function as a sensor; a sending coil, sending an alternating magnetic field based on a sending signal to a position indicator; and a signal processing circuit, connected to the detection coil and the sending coil, detecting a pen signal generated by the position indicator, and generating the sending signal having a frequency based on the frequency information of the detected pen signal and sending it to the sending coil.

[0026] Effects of the Invention

[0027] According to one or more embodiments of the present invention, the following effects are achieved: by suppressing the attenuation of the amplitude of the pen signal obtained from the circuit of the position indicator, it is possible to suppress the decrease in the position detection accuracy of the position indicator, the decrease in the detection accuracy of the pen pressure, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a diagram showing the structure of the input device according to the first embodiment of the present invention.

[0029] Figure 2 It is a diagram showing the operating principle of the position detector according to the first embodiment of the present invention.

[0030] Figure 3 This is a diagram showing an example of the configuration of a frequency analysis unit in the position detector according to the first embodiment of the present invention.

[0031] Figure 4A This is a diagram illustrating the frequency characteristics of the TX signal according to the first embodiment of the present invention.

[0032] Figure 4B This is a diagram illustrating a voltage waveform of a TX signal according to the first embodiment of the present invention.

[0033] Figure 5 This is a processing flow chart of the position detector according to the first embodiment of the present invention.

[0034] Figure 6 This is a processing flow chart of the position detector according to the first embodiment of the present invention.

[0035] Fig. 7A This is a diagram illustrating the frequency characteristics of the RX signal according to the first embodiment of the present invention.

[0036] Figure 7B This is a diagram illustrating a voltage waveform of an RX signal according to the first embodiment of the present invention.

[0037] Figure 8 It is a diagram showing the structure of an input device according to a second embodiment of the present invention.

[0038] Fig. 9 This is a diagram showing the relationship between the output from the frequency analysis unit of the position detector and the frequency / phase information sent to the multiplexer according to the second embodiment of the present invention.

[0039] Fig.10 This is a processing flow chart of the position detector according to the second embodiment of the present invention.

[0040] Fig.11 It is a diagram showing the structure of an input device according to a third embodiment of the present invention.

[0041] Fig.12 This is a diagram showing the relationship between the output from the frequency analysis unit of the position detector and the frequency / phase information sent to the multiplexer according to the third embodiment of the present invention.

[0042] Fig.13 This is a processing flow chart of the position detector according to the third embodiment of the present invention.

[0043] Fig.14A : is a diagram illustrating the frequency characteristics of a TX signal according to a conventional example.

[0044] Fig. 14B : is a diagram illustrating a voltage waveform of a TX signal according to a conventional example.

[0045] Fig.15A: is a diagram illustrating the frequency characteristics of the RX signal according to the conventional example.

[0046] Fig. 15B FIG. 2 is a diagram illustrating a voltage waveform of an RX signal according to a conventional example.

[0047] Fig.16 It is a diagram showing the operating principle of the position detector according to the fourth embodiment of the present invention.

[0048] Fig.17 This is a processing flow chart of the position detector according to the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0049] Hereinafter, regarding the embodiments of the present invention, refer to Figure 1 to Figure 13 , Figure 16-17 To explain.

[0050] <First Embodiment>

[0051] use Figure 1 7, the position detector 1 involved in this embodiment is described.

[0052] In addition, below, an input device including the position detector 1 according to the present embodiment is exemplified, and the position detector 1 according to the present embodiment is described.

[0053] <Structure of input device>

[0054] like Figure 1 As shown in FIG. 1 , the input device is configured to include a position detector 1 and a position indicator 2 according to the present embodiment.

[0055] <Structure of Position Indicator 2>

[0056] The position indicator 2 indicates the position of the position indicator 2 to the position detector 1 by electromagnetic induction.

[0057] like Figure 1 As shown, the position indicator 2 is composed of a position indicating coil 13 constituting a resonance circuit 61, a resonance capacitor 60a connected in parallel to the position indicating coil 13, and a variable capacitance capacitor 15 connected in parallel to the resonance capacitor 60a.

[0058] The resonance circuit 61 including the variable capacitance capacitor 15 resonates with a transmission signal received from a position detector 1 described later to transfer energy.

[0059] The position indicator 2 transmits the resonance signal detected by the resonance circuit 61 to the position detector 1 , thereby indicating the position of the position indicator 2 to the position detector 1 .

[0060] <Structure of Position Detector 1>

[0061] The position detector 1 is configured to include a position detection coil 101 and a signal processing circuit 102 .

[0062] The position detection coil 101 includes an X-axis direction loop coil group 104 a and a Y-axis direction loop coil group 104 b as sensors, which are stacked.

[0063] The X-axis direction loop coil group 104 a and the Y-axis direction loop coil group 104 b form the position detection coil 101 .

[0064] Each of the loop coil groups 104a and 104b is composed of, for example, 40 rectangular loop coils.

[0065] The loop coils constituting the loop coil groups 104 a and 104 b are arranged at equal intervals and sequentially overlapped.

[0066] The position detector 1 includes a selection circuit 106 connected to the X-axis direction loop coil group 104 a and the Y-axis direction loop coil group 104 b .

[0067] The selection circuit 106 sequentially selects one loop coil from the two loop coil groups 104 a and 104 b .

[0068] The signal processing circuit 102 includes a switching connection circuit 107 , a transmission amplifier 108 , a D / A conversion circuit 109 , a waveform generation unit 110 , a reception amplifier 111 , an A / D conversion circuit 112 , a frequency analysis unit 113 , and a control unit 120 .

[0069] Hereinafter, the structural block composed of the transmitting amplifier 108, the D / A conversion circuit 109 and the waveform generating unit 110 is referred to as a “TX unit”, and the structural block composed of the receiving amplifier 111, the A / D conversion circuit 112 and the frequency analyzing unit 113 is referred to as a “RX unit”.

[0070] The switching connection circuit 107 switches the connection destination ( Figure 1 The transmitting side terminal T and the receiving side terminal R).

[0071] The transmission-side terminal T of the connection destination is connected to the transmission amplifier 108 , and the reception-side terminal R is connected to the reception amplifier 111 .

[0072] The waveform generator 110 generates a transmission signal (hereinafter referred to as “TX signal”) to be supplied to the transmission coil 104 as the position detection coil 101 as shown in FIG. 4(A) based on a control signal obtained from the frequency analyzer 113 described later via the control unit 120 described later.

[0073] like Figure 2 As shown, the waveform generation unit 110 is configured to include a signal generation unit 110A and a multiplexer (MUX) 110B.

[0074] The signal generating unit 110A includes a plurality of signal generators that generate a plurality of transmission signals having different frequencies.

[0075] For example, Figure 2 As shown, the signal generating unit 110A generates a plurality of transmission signals having three different frequencies, namely, frequencies fTX, f′TX, and f″TX.

[0076] The output terminals of the plurality of signal generators of the signal generating section 110A are connected to the plurality of input terminals of the multiplexer 110B, respectively, and are connected to the output terminal of the multiplexer 110B based on a control signal from the control section 120 described later.

[0077] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a unique frequency.

[0078] Specifically, the multiplexer 110B outputs a TX signal equivalent to the frequency / phase of the RX signal input from the frequency analysis unit 113 described later, based on the frequency / phase information of the pen signal (hereinafter referred to as "RX signal") detected by the detection coil 104 serving as the position detection coil 101 analyzed in the frequency analysis unit 113 described later.

[0079] The analog voltage waveform of the TX signal transmitted to the position detector 1 via the transmission coil 104 as the position detection coil 101 is as shown in FIG. 4(B) .

[0080] The digital signal output from the waveform generating unit 110 is converted into an analog signal by the D / A converting circuit 109 , amplified by the transmitting amplifier 108 , and supplied to the transmitting terminal T of the switching connection circuit 107 .

[0081] The RX signal detected by the detection coil 104 as the position detection coil 101 is amplified by the reception amplifier 111 via the reception terminal R of the switching connection circuit 107 , converted into a digital signal by the A / D conversion circuit 112 , and supplied to the frequency analysis unit 113 .

[0082] The frequency analysis unit 113 receives the RX signal converted into a digital signal as input, and performs discrete Fourier transform processing.

[0083] The frequency analysis unit 113 outputs frequency / phase information of the RX signal to the control unit 120 described later as a result of executing the discrete Fourier transform process.

[0084] The frequency analysis unit 113 is, for example, Figure 3 The DFT shown has 1 input and 6 outputs, and performs frequency analysis on a plurality of discrete frequencies.

[0085] like Figure 2 As shown, the frequency analysis result in the frequency analysis unit 113 is fed back to the multiplexer 110B of the waveform generation unit 110 as a control signal.

[0086] The control unit 120 controls the entire signal processing circuit 102 based on a control program stored in a ROM (Read Only Memory) or the like (not shown), for example.

[0087] Specifically, the control unit 120 performs RX signal reception processing, discrete Fourier transform processing in the frequency analysis unit 113, frequency / phase information reception processing, signal multiplexing processing in the multiplexer 110B, signal generation processing in the signal generating unit 110A, and control of TX signal transmission processing.

[0088] The control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0089] Based on the pen signal generated by the position indicator 2 , the control unit 120 causes the waveform generation unit 110 to generate a transmission signal having a frequency different in accordance with the frequency of the pen signal.

[0090] The control unit 120 controls the operation of the multiplexer 110B so as to send an alternating magnetic field to the position indicator 2 via the sensors ( 104 a , 104 b ).

[0091] When the frequency of the pen signal generated by the position indicator 2 changes with respect to the frequency of the detected pen signal, the control unit 120 controls the operation of the multiplexer 110B so as to generate an output signal following the change in frequency.

[0092] The control unit 120 controls the operation of the multiplexer 110B so as to generate a transmission signal at a timing before the coordinate calculation process of the position indicator 2 starts.

[0093] The control unit 120 controls the operation of the multiplexer 110B so that the output signal is generated a plurality of times in one coordinate calculation process and the output signal of the same frequency is continuously generated during a plurality of times of performing at least one coordinate calculation process.

[0094] The control unit 120 generates an induced voltage in each loop coil of the X-axis direction loop coil group 104 a and the Y-axis direction loop coil group 104 b in response to the pen signal transmitted from the position indicator 2 .

[0095] The control unit 120 calculates the coordinate values ​​of the indicated position in the X-axis direction and the Y-axis direction of the position indicator 2 based on the levels of the voltage values ​​of the induced voltages generated in the respective loop coils.

[0096] The control unit 120 detects the writing pressure based on the phase difference between the transmitted transmission signal and the received pen signal.

[0097] <Processing of Position Detector 1>

[0098] use Figure 5 , Figure 6 , the processing of the position detector 1 involved in this embodiment is described.

[0099] It should be noted that the following description will be divided into a case where the process is started when the frequency / phase information of the RX signal changes and a case where the process is started at a timing before the coordinate calculation process of the position indicator 2 .

[0100] <When the processing starts when the frequency / phase information of the RX signal changes>

[0101] use Figure 5 , explaining the situation where processing starts when the frequency / phase information of the RX signal changes.

[0102] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0103] The RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analyzing unit 113 via the control unit 120 .

[0104] The frequency analysis unit 113 receives the RX signal converted into a digital signal as input, and performs discrete Fourier transform processing.

[0105] The frequency analysis unit 113 sends the frequency / phase information of the RX signal to the control unit 120 as the execution result of the discrete Fourier transform process (step S120 ).

[0106] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0107] The control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 to determine whether a change has occurred in the frequency / phase information of the RX signal (step S130 ).

[0108] Furthermore, when the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 and determines that there is no change in the frequency / phase information of the RX signal ("No" in step S130), the processing returns to the origin and transitions to the standby mode.

[0109] When the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 and determines that the frequency / phase information of the RX signal has changed ("Yes" in step S130), the control unit 120 sends the frequency / phase information of the RX signal from the frequency analysis unit 113 to the multiplexer 110B, and the multiplexer 110B receives the frequency / phase information of the sent RX signal (step S140).

[0110] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0111] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113 (step S150 ).

[0112] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0113] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0114] <Case where processing is started at a timing before coordinate calculation processing of position indicator 2>

[0115] use Figure 6 , the case where the processing is started at a timing before the coordinate calculation processing of the position indicator 2 is explained.

[0116] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0117] The RX signal received by the control unit 120 is converted into a desired digital signal.

[0118] The control unit 120 determines whether the current processing mode is the timing before the coordinate detection process (step S170 ).

[0119] Then, when the control unit 120 determines that the current processing mode is not the timing before the coordinate detection processing (No in step S170 ), the control unit 120 returns the processing to the origin and shifts to the standby mode.

[0120] When the control unit 120 determines that the current processing mode is the timing before the coordinate detection process (Yes in step S170 ), the RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analysis unit 113 via the control unit 120 .

[0121] The frequency analysis unit 113 receives the RX signal converted into a digital signal from the control unit 120 and performs discrete Fourier transform processing.

[0122] The frequency analysis unit 113 outputs the frequency / phase information of the RX signal to the multiplexer 110B as a result of the discrete Fourier transform process (step S120 ).

[0123] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0124] The multiplexer 110B receives the frequency / phase information of the RX signal from the frequency analysis unit 113 (step S140 ).

[0125] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0126] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113 (step S150 ).

[0127] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0128] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0129] <Function and Effect>

[0130] As described above, the position detector 1 involved in this embodiment includes: a sensor (for example, an X-axis direction annular coil group 104a, a Y-axis direction annular coil group 104b), which is equipped with multiple electrodes; and a signal processing circuit 102, which is connected to the sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b), detects the pen signal generated by the position indicator 2, generates a send signal with a frequency different from the frequency of the detected pen signal, and sends an alternating magnetic field to the position indicator 2 via the sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b).

[0131] That is, the signal processing circuit 102 of the position detector 1 involved in this embodiment detects the pen signal generated by the position indicator 2, generates a send signal with a frequency different from the frequency of the detected pen signal, and sends an alternating magnetic field to the position indicator 2 via a sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b).

[0132] For example, the position detector 1 according to the present embodiment generates a transmission signal having a frequency that differs according to the behavior of the position pointer 2 , for example, the presence or absence of a writing pressure in the position pointer 2 , and transmits the signal to the position pointer 2 .

[0133] More specifically, for example, as shown in FIG. 4(A) , the position detector 1 according to the present embodiment transmits a transmission signal having a frequency corresponding to the frequency transmitted from the position indicator 2 to the position indicator 2 .

[0134] Therefore, the resonance energy supplied to the position indicator 2 is maintained regardless of the presence or absence of the writing pressure in the position indicator 2, and therefore, as shown in FIG. 4(B) , the amplitude of the voltage waveform sent from the position indicator 2 is also maintained.

[0135] In addition, in the conventional position indicator 2 , when the resonance frequency becomes f′pen due to the writing pressure, the position indicator 2 can obtain only the resonance energy based on the frequency characteristic of fTX, and the resonance signal is attenuated.

[0136] In this embodiment, as shown in FIG. 7(A) and FIG. 7(B), the position indicator 2 can obtain resonance energy based on the frequency characteristics of f″TX, and thus can obtain a resonance signal equivalent to that in the case of no writing pressure without attenuating the resonance signal.

[0137] Therefore, even when a pen pressure is generated in the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 .

[0138] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0139] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0140] Since the resonance energy supplied to the position indicator 2 is optimized, it is possible to expect improvement in position detection accuracy even for the position indicator 2 in a hovering state, for example.

[0141] Since the resonant energy supplied to the position indicator 2 is optimized, even if, for example, the magnet, the metal shell, etc. deteriorate over time or the value of the position indication coil or the resonant capacitor forming the resonant circuit in the position indicator 2 changes due to environmental conditions, etc., the decrease in the S / N of the pen signal sent from the position indicator 2 can be suppressed.

[0142] When the frequency of the pen signal generated by the position pointer 2 changes with respect to the frequency of the detected pen signal, the signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal following the change in frequency.

[0143] That is, the signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal that follows the change in the frequency of the pen signal generated by the position pointer 2 .

[0144] For example, the position detector 1 according to the present embodiment generates a transmission signal following a frequency that changes according to the behavior of the position pointer 2 , for example, the presence or absence of a writing pressure in the position pointer 2 .

[0145] More specifically, for example, as shown in FIG. 4(A) , the position detector 1 according to the present embodiment transmits a transmission signal having a frequency corresponding to the frequency transmitted from the position indicator 2 to the position indicator 2 .

[0146] Therefore, the resonance energy supplied to the position indicator 2 is maintained regardless of the presence or absence of the writing pressure in the position indicator 2, and therefore, as shown in FIG. 4(B) , the amplitude of the voltage waveform sent from the position indicator 2 is also maintained.

[0147] In addition, in the conventional position indicator 2 , when the resonance frequency becomes f′pen due to the writing pressure, the position indicator 2 can obtain only the resonance energy based on the frequency characteristic of fTX, and the resonance signal is attenuated.

[0148] In this embodiment, as shown in FIG. 7(A) and FIG. 7(B), the position indicator 2 can obtain resonance energy based on the frequency characteristics of f″TX, and thus can obtain a resonance signal equivalent to that in the case of no writing pressure without attenuating the resonance signal.

[0149] Therefore, even when a pen pressure is generated in the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 .

[0150] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0151] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0152] The signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal at a timing before the coordinate calculation process of the position indicator 2 starts.

[0153] That is, the decrease in the S / N ratio of the pen signal sent from the position indicator 2 has the greatest influence on the coordinate calculation process of the position indicator 2 .

[0154] However, in the signal processing circuit 102 of the position detector 1 according to the present embodiment, a transmission signal is generated at a timing before the coordinate calculation process of the position indicator 2 is started.

[0155] Therefore, in the coordinate calculation process of the position pointer 2, the coordinate calculation process can be executed using the pen signal sent from the position pointer 2 with the reduction in S / N suppressed.

[0156] In addition, in the signal processing circuit 102 of the position detector 1 according to the present embodiment, a transmission signal is generated at a timing before the coordinate calculation process of the position indicator 2 is started.

[0157] Therefore, by optimizing the activation timing of the waveform generating unit 110 and the D / A converting circuit 109 , it is possible to suppress the power consumption of the waveform generating unit 110 and the D / A converting circuit 109 to a minimum.

[0158] Therefore, even if a pen pressure is applied to the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 while suppressing power consumption to a minimum.

[0159] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0160] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0161] The signal processing circuit 102 of the position detector 1 according to the present embodiment generates a plurality of transmission signals in one coordinate calculation process, and continuously generates transmission signals at the same frequency during a plurality of times of performing at least one coordinate calculation process.

[0162] For example, when calculating the coordinates of the position indicator 2 existing in an N×N area within the sensor, in other words, in one coordinate calculation process, sensing is performed on N X sensors and N Y sensors, that is, a process of generating transmission signals a plurality of times is performed, and the coordinate calculation process is executed based on the reception intensity distribution of the sensors.

[0163] Here, if the frequency of the transmitted signal is changed during the sensing of the N X sensors and the N Y sensors, that is, during multiple times of one coordinate calculation process, the amplitude level of the pen signal may change, and accurate coordinates may not be calculated.

[0164] Therefore, the signal processing circuit 102 generates the send signal multiple times in one coordinate calculation process, and continuously generates the send signal at the same frequency during multiple times of performing at least one coordinate calculation process, thereby preventing adverse effects caused by dynamically changing the frequency.

[0165] <Second Embodiment>

[0166] use Figure 8~Figure 10 , the position detector 1A according to the present embodiment will be described.

[0167] It should be noted that the position detector 1A according to the present embodiment is different from the position detector 1 according to the first embodiment only in the configuration of the frequency analysis unit 113A, and therefore only matters related to the frequency analysis unit 113A will be described below.

[0168] <Configuration of Signal Processing Circuit 102A>

[0169] like Figure 8 As shown, the signal processing circuit 102A of the position detector 1A involved in this embodiment is configured to include a switching connection circuit 107, a transmitting amplifier 108, a D / A conversion circuit 109, a waveform generating unit 110, a receiving amplifier 111, an A / D conversion circuit 112, a frequency analysis unit 113A and a control unit 120.

[0170] It should be noted that components denoted by the same reference numerals as those in the first embodiment have the same functions, and thus detailed description thereof will be omitted.

[0171] The frequency analysis unit 113A performs frequency analysis on a plurality of discrete frequencies.

[0172] The frequency analyzing unit 113A extracts, as a frequency, a discrete value that is closest to a peak value of the wave height value of the pen signal received from the position indicator 2 among the discrete values ​​detected by the frequency.

[0173] For example, Fig. 9As shown, the frequency analysis unit 113A performs discrete Fourier transform processing on one input at six frequencies, and outputs the processing result as digital data of the wave height value of the pen signal at each frequency.

[0174] That is, for the peak value with respect to each frequency as a discrete value, for example, when the frequency at which the peak value shows a peak does not match each frequency as a discrete value, the frequency analyzing unit 113A extracts the nearest discrete value at which the peak value shows a peak as the frequency.

[0175] For example, in Fig. 9 In the example shown, the frequency at which the peak value is peaked is D2-3, and the frequency of the nearest discrete value is D2. Therefore, the frequency analysis unit 113A extracts D2 as the frequency and sends D2 as the frequency / phase information.

[0176] <Processing of Position Detector 1A>

[0177] use Fig.10 , the processing of the position detector 1A involved in this embodiment is described.

[0178] The following description will take as an example a case where the process is started when the frequency / phase information of the RX signal changes.

[0179] It should be noted that, when the process is started at a timing before the coordinate calculation process of the position indicator 2, only the timing of starting the process is different, and the other processes are the same.

[0180] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0181] The RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analyzing unit 113A via the control unit 120 .

[0182] The frequency analysis unit 113A receives the RX signal converted into a digital signal as input, and performs discrete Fourier transform processing.

[0183] The frequency analyzing unit 113A extracts, as a frequency, a discrete value closest to the peak value of the pen signal received from the position indicator 2 among the discrete values ​​of frequency detection, and obtains it as an execution result of discrete Fourier transform processing.

[0184] The frequency analysis unit 113A sends the frequency / phase information of the RX signal to the control unit 120 as the execution result of the discrete Fourier transform process (step S120A).

[0185] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113A in the memory.

[0186] The control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113A to determine whether a change has occurred in the frequency / phase information of the RX signal (step S130 ).

[0187] Furthermore, when the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113A and determines that there is no change in the frequency / phase information of the RX signal ("No" in step S130), the processing returns to the origin and transitions to the standby mode.

[0188] When the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113A and determines that the frequency / phase information of the RX signal has changed ("Yes" in step S130), the multiplexer 110B receives the frequency / phase information of the RX signal from the frequency analysis unit 113A (step S140).

[0189] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0190] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113A (step S150 ).

[0191] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0192] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0193] <Function and Effect>

[0194] As described above, the signal processing circuit 102A of the position detector 1A according to the present embodiment performs frequency analysis on a plurality of discrete frequencies and extracts as the frequency the discrete value closest to the peak value of the wave height of the pen signal received from the position indicator 2 among the discrete values ​​of the frequency detection.

[0195] That is, for example, Fig. 9 As shown, when the frequency at which the wave height value presents a peak is D2-3, the frequency at which the wave height value presents a peak is D2 as the nearest discrete value.

[0196] Here, the interval between discrete values ​​is sufficiently small, therefore, by making the frequency information with a peak wave height value D2 and sending it to the multiplexer 110B and outputting the TX signal in the signal generating unit 110A, it is possible to expect the effect of suppressing the decrease in the S / N of the pen signal sent from the position indicator 2, assuming that a pen pressure is generated in the position indicator 2.

[0197] Since the effect of suppressing a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be expected, the effect of suppressing a decrease in the position detection accuracy of the position indicator can be expected.

[0198] Since the effect of suppressing a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be expected, the effect of suppressing a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be expected.

[0199] <Third Embodiment>

[0200] use Figure 11~Figure 13 , the position detector 1B involved in this embodiment is described.

[0201] It should be noted that the position detector 1B according to the present embodiment differs from the position detectors 1 and 1A according to the first and second embodiments only in the structure of the frequency analysis unit 113B, and therefore only matters related to the frequency analysis unit 113B will be described below.

[0202] <Configuration of Signal Processing Circuit 102B>

[0203] like Figure 8 As shown, the signal processing circuit 102B of the position detector 1A involved in this embodiment is configured to include a switching connection circuit 107, a transmitting amplifier 108, a D / A conversion circuit 109, a waveform generating unit 110, a receiving amplifier 111, an A / D conversion circuit 112, a frequency analysis unit 113B and a control unit 120.

[0204] It should be noted that components denoted by the same reference numerals as those in the first embodiment and the second embodiment have the same functions, and thus detailed description thereof will be omitted.

[0205] When the frequency at which the peak value of the pen signal received from the position indicator 2 shows a peak and the discrete value of the frequency detection do not match, the frequency analysis unit 113B performs interpolation operation at the frequency at which the peak value shows a peak and the adjacent discrete value of the frequency detection to extract the frequency.

[0206] For example, Figure 3As shown, the frequency analysis unit 113B performs discrete Fourier transform processing on one input at six frequencies, and outputs the processing result as digital data of the wave height value of the pen signal at each frequency.

[0207] For example, in Fig.12 In the example shown, the frequency at which the wave height value presents a peak is D2-3.

[0208] The frequency analyzing unit 113B performs interpolation calculation at three points, namely, the frequency (D2-3) at which the wave height value has a peak and the discrete values ​​(D2 and D3) of the adjacent frequency detections, to extract the frequency (D2-3) at which the wave height value has a peak.

[0209] <Processing of Position Detector 1B>

[0210] use Fig.13 , the processing of the position detector 1B involved in this embodiment is described.

[0211] The following description will take as an example a case where the process is started when the frequency / phase information of the RX signal changes.

[0212] It should be noted that, when the process is started at a timing before the coordinate calculation process of the position indicator 2, only the timing of starting the process is different, and the other processes are the same.

[0213] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0214] The RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analyzing unit 113B via the control unit 120 .

[0215] The frequency analysis unit 113B receives the RX signal converted into a digital signal and performs discrete Fourier transform processing.

[0216] When the frequency at which the peak value of the pen signal received from the position indicator 2 shows a peak and the discrete value of the frequency detection do not match, the frequency analysis unit 113B performs interpolation operation at the frequency at which the peak value shows a peak and the adjacent discrete value of the frequency detection to extract the frequency.

[0217] The frequency analysis unit 113B sends the frequency / phase information of the RX signal to the control unit 120 as the execution result of the discrete Fourier transform process (step S120B).

[0218] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113B in the memory.

[0219] The control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113B to determine whether a change has occurred in the frequency / phase information of the RX signal (step S130 ).

[0220] Furthermore, when the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113B and determines that there is no change in the frequency / phase information of the RX signal ("No" in step S130), the processing returns to the origin and transitions to the standby mode.

[0221] When the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113B and determines that the frequency / phase information of the RX signal has changed ("Yes" in step S130), the multiplexer 110B receives the frequency / phase information of the RX signal from the frequency analysis unit 113B (step S140).

[0222] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0223] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113B (step S150 ).

[0224] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0225] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0226] <Function and Effect>

[0227] As described above, the signal processing circuit 102B of the position detector 1A involved in this embodiment performs interpolation operation at the frequency at which the wave height value presents a peak and the discrete value of the adjacent frequency detection to extract the frequency when the frequency at which the wave height value of the pen signal received from the position indicator 2 presents a peak is inconsistent with the discrete value of the frequency detection.

[0228] That is, for example, Fig.12 As shown, when the frequency at which the wave height value presents a peak is D2-3, interpolation operation is performed at three points, namely, the frequency at which the wave height value presents a peak (D2-3) and the discrete values ​​of adjacent frequency detections (D2 and D3), to extract the frequency at which the wave height value presents a peak (D2-3).

[0229] Therefore, by extracting the frequency (D2-3) at which the wave height value close to the true value shows a peak, even when it is assumed that pen pressure occurs in the position indicator 2, the reduction in the S / N of the pen signal sent from the position indicator 2 can be suppressed.

[0230] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator 2 can be suppressed.

[0231] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0232] <Fourth Embodiment>

[0233] use Figure 1 , Figure 3 Figure 4 Figure 6 Figure 7 Fig.16 , Fig.17 , the position detector 1 involved in this embodiment is described.

[0234] In addition, below, an input device including the position detector 1 according to the present embodiment is exemplified, and the position detector 1 according to the present embodiment is described.

[0235] <Structure of input device>

[0236] like Figure 1 As shown in FIG. 1 , the input device is configured to include a position detector 1 and a position indicator 2 according to the present embodiment.

[0237] <Structure of Position Indicator 2>

[0238] The position indicator 2 indicates the position of the position indicator 2 to the position detector 1 by electromagnetic induction.

[0239] like Figure 1 As shown, the position indicator 2 is composed of a position indicating coil 13 constituting a resonance circuit 61, a resonance capacitor 60a connected in parallel to the position indicating coil 13, and a variable capacitance capacitor 15 connected in parallel to the resonance capacitor 60a.

[0240] The resonance circuit 61 including the variable capacitance capacitor 15 resonates with a transmission signal received from a position detector 1 described later to transfer energy.

[0241] The position indicator 2 transmits the resonance signal detected by the resonance circuit 61 to the position detector 1 , thereby indicating the position of the position indicator 2 to the position detector 1 .

[0242] <Structure of Position Detector 1>

[0243] The position detector 1 is configured to include a position detection coil 101 and a signal processing circuit 102 .

[0244] The position detection coil 101 includes an X-axis direction loop coil group 104 a and a Y-axis direction loop coil group 104 b as sensors, which are stacked.

[0245] The X-axis direction loop coil group 104 a and the Y-axis direction loop coil group 104 b form the position detection coil 101 .

[0246] Each of the loop coil groups 104a and 104b is composed of, for example, 40 rectangular loop coils.

[0247] The loop coils constituting the loop coil groups 104 a and 104 b are arranged at equal intervals and sequentially overlapped.

[0248] The position detector 1 includes a selection circuit 106 connected to the X-axis direction loop coil group 104 a and the Y-axis direction loop coil group 104 b .

[0249] The selection circuit 106 sequentially selects one loop coil from the two loop coil groups 104 a and 104 b .

[0250] The signal processing circuit 102 includes a switching connection circuit 107 , a transmission amplifier 108 , a D / A conversion circuit 109 , a waveform generation unit 110 , a reception amplifier 111 , an A / D conversion circuit 112 , a frequency analysis unit 113 , and a control unit 120 .

[0251] Hereinafter, the structural block composed of the transmitting amplifier 108, the D / A conversion circuit 109 and the waveform generating unit 110 is referred to as a “TX unit”, and the structural block composed of the receiving amplifier 111, the A / D conversion circuit 112 and the frequency analyzing unit 113 is referred to as a “RX unit”.

[0252] The switching connection circuit 107 switches the connection destination ( Figure 1 The transmitting side terminal T and the receiving side terminal R).

[0253] The transmission-side terminal T of the connection destination is connected to the transmission amplifier 108 , and the reception-side terminal R is connected to the reception amplifier 111 .

[0254] The waveform generator 110 generates a transmission signal (hereinafter referred to as “TX signal”) to be supplied to the transmission coil 104 as the position detection coil 101 as shown in FIG. 4(A) based on a control signal obtained from the frequency analyzer 113 described later via the control unit 120 described later.

[0255] like Fig.16 As shown, the waveform generation unit 110 is configured to include a signal generation unit 110A and a multiplexer (MUX) 110B.

[0256] The signal generating unit 110A includes a plurality of signal generators that generate a plurality of transmission signals having different frequencies.

[0257] For example, Fig.16 As shown, the signal generating unit 110A generates a plurality of transmission signals having three different frequencies, namely, frequencies fTX, f′TX, and f″TX.

[0258] The output terminals of the plurality of signal generators of the signal generating section 110A are connected to the plurality of input terminals of the multiplexer 110B, respectively, and are connected to the output terminal of the multiplexer 110B based on a control signal from the control section 120 described later.

[0259] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a unique frequency.

[0260] Specifically, the multiplexer 110B outputs a TX signal corresponding to the frequency / phase of the RX signal input from the frequency analysis unit 113 described later, based on the frequency / phase information of the pen signal (hereinafter referred to as "RX signal") detected by the detection coil 104 serving as the position detection coil 101 analyzed in the frequency analysis unit 113 described later.

[0261] The analog voltage waveform of the TX signal transmitted to the position detector 1 via the transmission coil 104 as the position detection coil 101 is as shown in FIG. 4(B) .

[0262] The digital signal output from the waveform generating unit 110 is converted into an analog signal by the D / A converting circuit 109 , amplified by the transmitting amplifier 108 , and supplied to the transmitting terminal T of the switching connection circuit 107 .

[0263] The RX signal detected by the detection coil 104 as the position detection coil 101 is amplified by the reception amplifier 111 via the reception terminal R of the switching connection circuit 107 , converted into a digital signal by the A / D conversion circuit 112 , and supplied to the frequency analysis unit 113 .

[0264] The frequency analysis unit 113 receives the RX signal converted into a digital signal as input, and performs discrete Fourier transform processing.

[0265] The frequency analysis unit 113 outputs frequency / phase information of the RX signal to the control unit 120 described later as a result of executing the discrete Fourier transform process.

[0266] The frequency analysis unit 113 is, for example, Figure 3 The DFT shown has 1 input and 6 outputs, and performs frequency analysis on a plurality of discrete frequencies.

[0267] like Fig.16 As shown, the analysis result of the frequency in the frequency analysis unit 113 is fed back to the multiplexer 110B of the waveform generation unit 110 via the control unit 120 as a control signal.

[0268] The control unit 120 controls the entire signal processing circuit 102 based on a control program stored in a ROM (Read Only Memory) or the like (not shown), for example.

[0269] Specifically, the control unit 120 performs RX signal reception processing, discrete Fourier transform processing in the frequency analysis unit 113, frequency / phase information reception processing, signal multiplexing processing in the multiplexer 110B, signal generation processing in the signal generating unit 110A, and control of TX signal transmission processing.

[0270] The control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0271] The control unit 120 causes the waveform generation unit 110 to generate a transmission signal having a frequency different in accordance with the frequency of the pen signal, based on the RX signal obtained from the frequency analysis unit 113 , that is, the pen signal generated by the position indicator 2 .

[0272] The control unit 120 controls the operation of the multiplexer 110B so as to send an alternating magnetic field to the position indicator 2 via the sensors ( 104 a , 104 b ).

[0273] When the frequency of the pen signal generated by the position indicator 2 changes with respect to the frequency of the detected pen signal, the control unit 120 controls the operation of the multiplexer 110B so as to generate an output signal following the change in frequency.

[0274] The control unit 120 controls the operation of the multiplexer 110B so as to generate a transmission signal at a timing before the coordinate calculation process of the position indicator 2 starts.

[0275] The control unit 120 controls the operation of the multiplexer 110B so that the output signal is generated a plurality of times in one coordinate calculation process and the output signal of the same frequency is continuously generated during a plurality of times of performing at least one coordinate calculation process.

[0276] The control unit 120 calculates the coordinate values ​​of the indicated position in the X-axis direction and the Y-axis direction of the position indicator 2 based on the voltage value levels of the induced voltages generated in each circular coil of the X-axis direction circular coil group 104a and the Y-axis direction circular coil group 104b due to the pen signal sent from the position indicator 2.

[0277] The control unit 120 detects the writing pressure based on the phase difference between the transmitted transmission signal and the received pen signal.

[0278] <Processing of Position Detector 1>

[0279] use Fig.17 , Figure 6 , the processing of the position detector 1 involved in this embodiment is described.

[0280] It should be noted that the following description will be divided into a case where the process is started when the frequency / phase information of the RX signal changes and a case where the process is started at a timing before the coordinate calculation process of the position indicator 2 .

[0281] <When the processing starts when the frequency / phase information of the RX signal changes>

[0282] use Fig.17 , explaining the situation where processing starts when the frequency / phase information of the RX signal changes.

[0283] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0284] The RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analyzing unit 113 via the control unit 120 .

[0285] The frequency analysis unit 113 receives the RX signal converted into a digital signal as input, and performs discrete Fourier transform processing.

[0286] The frequency analysis unit 113 sends the frequency / phase information of the RX signal to the control unit 120 as the execution result of the discrete Fourier transform process (step S120 ).

[0287] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0288] The control unit 120 compares the frequency / phase information of the past RX signal with the frequency / phase information of the RX signal obtained this time from the frequency analysis unit 113 to determine whether the frequency / phase information of the RX signal has changed (step S130A).

[0289] When the control unit 120 compares the frequency / phase information of the past RX signal with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 and determines that the frequency / phase information of the RX signal has changed ("Yes" in step S130A), the control unit 120 sends the frequency / phase information of the RX signal from the frequency analysis unit 113 to the multiplexer 110B, and the multiplexer 110B receives the frequency / phase information of the sent RX signal (step S140).

[0290] On the other hand, when the control unit 120 compares the frequency / phase information of the RX signal in the memory with the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 and determines that there is no change in the frequency / phase information of the RX signal ("No" in step S130A), the processing of step S140 is not performed, and the processing of step S150 described later is performed.

[0291] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0292] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113 (step S150 ).

[0293] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0294] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0295] <Case where processing is started at a timing before coordinate calculation processing of position indicator 2>

[0296] use Figure 6 , the case where the processing is started at a timing before the coordinate calculation processing of the position indicator 2 is explained.

[0297] The control unit 120 causes the signal receiving unit to receive the RX signal from the position indicator 2 (step S110 ).

[0298] The RX signal received by the control unit 120 is converted into a desired digital signal.

[0299] The control unit 120 determines whether the current processing mode is the timing before the coordinate detection process (step S170 ).

[0300] Then, when the control unit 120 determines that the current processing mode is not the timing before the coordinate detection processing (No in step S170 ), the control unit 120 returns the processing to the origin and shifts to the standby mode.

[0301] When the control unit 120 determines that the current processing mode is the timing before the coordinate detection process (Yes in step S170 ), the RX signal received by the signal receiving unit is converted into a desired digital signal and sent to the frequency analysis unit 113 via the control unit 120 .

[0302] The frequency analysis unit 113 receives the RX signal converted into a digital signal from the control unit 120 and performs discrete Fourier transform processing.

[0303] The frequency analysis unit 113 outputs the frequency / phase information of the RX signal to the multiplexer 110B as a result of the discrete Fourier transform process (step S120 ).

[0304] At this time, the control unit 120 stores the frequency / phase information of the RX signal obtained from the frequency analysis unit 113 in the memory.

[0305] The multiplexer 110B receives the frequency / phase information of the RX signal from the frequency analysis unit 113 (step S140 ).

[0306] The signal generating unit 110A generates a plurality of transmission signals having different frequencies.

[0307] The multiplexer 110B inputs a plurality of transmission signals having different frequencies from the signal generator 110A, multiplexes the signals, and outputs a TX signal having a frequency and a phase corresponding to the RX signal input from the frequency analyzer 113 (step S150 ).

[0308] The control unit 120 transmits the TX signal to the position indicator 2 via the signal transmission unit.

[0309] The TX signal output from the control unit 120 is transmitted to the position detection coil 101 of the position indicator 2 via the switching connection circuit 107 (step S160 ).

[0310] <Function and Effect>

[0311] As described above, the position detector 1 involved in this embodiment includes: a sensor (for example, an X-axis direction annular coil group 104a, a Y-axis direction annular coil group 104b), which is equipped with multiple electrodes; and a signal processing circuit 102, which is connected to the sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b), detects the pen signal generated by the position indicator 2, generates a send signal with a frequency different from the frequency of the detected pen signal, and sends an alternating magnetic field to the position indicator 2 via the sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b).

[0312] That is, the signal processing circuit 102 of the position detector 1 involved in this embodiment detects the pen signal generated by the position indicator 2, generates a send signal with a frequency different from the frequency of the detected pen signal, and sends an alternating magnetic field to the position indicator 2 via a sensor (for example, the X-axis direction annular coil group 104a, the Y-axis direction annular coil group 104b).

[0313] For example, the position detector 1 according to the present embodiment generates a transmission signal having a frequency that differs according to the behavior of the position pointer 2 , for example, the presence or absence of a writing pressure in the position pointer 2 , and transmits the signal to the position pointer 2 .

[0314] More specifically, for example, as shown in FIG. 4(A) , the position detector 1 according to the present embodiment transmits a transmission signal having a frequency corresponding to the frequency transmitted from the position indicator 2 to the position indicator 2 .

[0315] Therefore, the resonance energy supplied to the position indicator 2 is maintained regardless of the presence or absence of the writing pressure in the position indicator 2, and therefore, as shown in FIG. 4(B) , the amplitude of the voltage waveform sent from the position indicator 2 is also maintained.

[0316] In addition, in the conventional position indicator 2 , when the resonance frequency becomes f′pen due to the writing pressure, the position indicator 2 can obtain only the resonance energy based on the frequency characteristic of fTX, and the resonance signal is attenuated.

[0317] In this embodiment, as shown in FIG. 7(A) and FIG. 7(B), the position indicator 2 can obtain resonance energy based on the frequency characteristics of f″TX, and thus can obtain a resonance signal equivalent to that in the case of no writing pressure without attenuating the resonance signal.

[0318] Therefore, even when a pen pressure is generated in the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 .

[0319] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0320] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0321] Since the resonance energy supplied to the position indicator 2 is optimized, it is possible to expect improvement in position detection accuracy even for the position indicator 2 in a hovering state, for example.

[0322] Since the resonant energy supplied to the position indicator 2 is optimized, even if, for example, the magnet, the metal shell, etc. deteriorate over time or the value of the position indication coil or the resonant capacitor forming the resonant circuit in the position indicator 2 changes due to environmental conditions, etc., the decrease in the S / N of the pen signal sent from the position indicator 2 can be suppressed.

[0323] When the frequency of the pen signal generated by the position pointer 2 changes with respect to the frequency of the detected pen signal, the signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal following the change in frequency.

[0324] That is, the signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal that follows the change in the frequency of the pen signal generated by the position pointer 2 .

[0325] For example, the position detector 1 according to the present embodiment generates a transmission signal following a frequency that changes according to the behavior of the position pointer 2 , for example, the presence or absence of a writing pressure in the position pointer 2 .

[0326] More specifically, for example, as shown in FIG. 4(A) , the position detector 1 according to the present embodiment transmits a transmission signal having a frequency corresponding to the frequency transmitted from the position indicator 2 to the position indicator 2 .

[0327] Therefore, the resonance energy supplied to the position indicator 2 is maintained regardless of the presence or absence of the writing pressure in the position indicator 2, and therefore, as shown in FIG. 4(B) , the amplitude of the voltage waveform sent from the position indicator 2 is also maintained.

[0328] In addition, in the conventional position indicator 2 , when the resonance frequency becomes f′pen due to the writing pressure, the position indicator 2 can obtain only the resonance energy based on the frequency characteristic of fTX, and the resonance signal is attenuated.

[0329] In this embodiment, as shown in FIG. 7(A) and FIG. 7(B), the position indicator 2 can obtain resonance energy based on the frequency characteristics of f"TX, so it is possible to obtain a resonance signal equivalent to the case where there is no writing pressure without attenuating the resonance signal.

[0330] Therefore, even when a pen pressure is generated in the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 .

[0331] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0332] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0333] The signal processing circuit 102 of the position detector 1 according to the present embodiment generates a transmission signal at a timing before the coordinate calculation process of the position indicator 2 starts.

[0334] That is, the decrease in the S / N ratio of the pen signal sent from the position indicator 2 has the greatest influence on the coordinate calculation process of the position indicator 2 .

[0335] However, in the signal processing circuit 102 of the position detector 1 according to the present embodiment, a transmission signal is generated at a timing before the coordinate calculation process of the position indicator 2 is started.

[0336] Therefore, in the coordinate calculation process of the position pointer 2, the coordinate calculation process can be executed using the pen signal sent from the position pointer 2 with the reduction in S / N suppressed.

[0337] In addition, in the signal processing circuit 102 of the position detector 1 according to the present embodiment, a transmission signal is generated at a timing before the coordinate calculation process of the position indicator 2 is started.

[0338] Therefore, by optimizing the activation timing of the waveform generating unit 110 and the D / A converting circuit 109 , it is possible to suppress the power consumption of the waveform generating unit 110 and the D / A converting circuit 109 to a minimum.

[0339] Therefore, even if a pen pressure is applied to the position indicator 2 , it is possible to suppress a decrease in the S / N ratio of the pen signal sent from the position indicator 2 while suppressing power consumption to a minimum.

[0340] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the position detection accuracy of the position indicator can be suppressed.

[0341] Since a decrease in the S / N ratio of the pen signal sent from the position indicator 2 can be suppressed, a decrease in the detection accuracy of the pen pressure in the position indicator 2 can be suppressed.

[0342] The signal processing circuit 102 of the position detector 1 according to the present embodiment generates a plurality of transmission signals in one coordinate calculation process, and continuously generates transmission signals at the same frequency during a plurality of times of performing at least one coordinate calculation process.

[0343] For example, when calculating the coordinates of the position indicator 2 existing in an N×N area within the sensor, in other words, in one coordinate calculation process, sensing is performed on N X sensors and N Y sensors, that is, a process of generating transmission signals a plurality of times is performed, and the coordinate calculation process is executed based on the reception intensity distribution of the sensors.

[0344] Here, if the frequency of the transmitted signal is changed during the sensing of the N X sensors and the N Y sensors, that is, during multiple times of one coordinate calculation process, the amplitude level of the pen signal may change, and accurate coordinates may not be calculated.

[0345] Therefore, the signal processing circuit 102 generates the send signal multiple times in one coordinate calculation process, and continuously generates the send signal at the same frequency during multiple times of performing at least one coordinate calculation process, thereby preventing adverse effects caused by dynamically changing the frequency.

[0346] In the above-described embodiment, the sensor is exemplified as a state in which rectangular coils are arranged in a two-dimensional space in a first direction and a second direction in a manner intersecting with each other on a substrate, but the present invention is not limited thereto.

[0347] For example, although the sending coil for generating an alternating magnetic field for the position indicator 2 and the detecting coil for detecting a pen signal generated by the position indicator 2 are described as being the same coil and being used in a time-division manner, they may be separate coils.

[0348] In addition, for example, the sending coil and the detecting coil may be provided on separate substrates and separated.

[0349] In this case, the pen signal may be detected by the detection coil in one layer, and an alternating magnetic field having a frequency corresponding to (following) the frequency may be generated from the sending coil provided in another layer.

[0350] Furthermore, the arrangement is not limited to rectangular coils arranged in two directions, and for example, block-shaped coils may be spread out two-dimensionally to cover the detection surface.

[0351] Furthermore, even if the plurality of electrodes constituting the sensor do not have a ring-shaped coil shape, they may be a part of electrodes that electromagnetically form a coil.

[0352] For example, as specific examples, a comb-shaped coil, a case where two wirings function as a coil in a pseudo manner, etc. can be exemplified.

[0353] It should be noted that the processing of the control unit 120, 120A, 120B can be recorded in a recording medium readable by a computer system, and the position detector 1, 1A, 1B of the present invention can be realized by making the control unit 120, 120A, 120B read and execute the program recorded in the recording medium. The computer system mentioned here includes hardware such as OS and peripheral devices.

[0354] In addition, if the "computer system" uses the WWW (World Wide Web) system, it also includes a homepage providing environment (or display environment). In addition, the above-mentioned program can also be transmitted from a computer system that stores the program in a storage device or the like to another computer system via a transmission medium or a transmission wave in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet, a communication line (communication line) such as a telephone line, etc.

[0355] In addition, the above-mentioned program may be a program for realizing a part of the above-mentioned functions. Furthermore, it may be a program that can realize the above-mentioned functions by combining with a program already recorded in the computer system, that is, a so-called differential file (differential program).

[0356] As mentioned above, although the embodiment of the present invention has been described in detail with reference to the drawings, the specific structure is not limited to the embodiment, and also includes designs and the like within the scope not departing from the gist of the present invention.

[0357] For example, the position indicator 2 exemplified in the first to fourth embodiments includes an electronic pen, a touch pen, or the like, but its shape is not necessarily limited to a pen shape.

[0358] <Additional Notes>

[0359] A position detector comprises: one or more processors; one or more memories connected to the one or more processors in a communicable manner; and a coil configured to function as a sensor, including a sending coil that sends an alternating magnetic field based on a sending signal to a position indicator,

[0360] The one or more processors include a signal processing circuit, which is connected to the coil, detects the pen signal generated by the position indicator, and generates the send signal having a frequency based on the frequency information of the detected pen signal and sends it to the send coil.

[0361] Description of Reference Numerals

[0362] 1: Position detector

[0363] 1A: Position detector

[0364] 1B: Position detector

[0365] 2: Position indicator

[0366] 101: Position detection coil

[0367] 102: Signal processing circuit

[0368] 104a: X-axis direction annular coil group

[0369] 104b: Y-axis direction annular coil group

[0370] 106: Select Circuit

[0371] 107: Switch connection circuit

[0372] 108: Transmitter Amplifier

[0373] 109: D / A conversion circuit

[0374] 110: Waveform generation unit

[0375] 110A: Signal generating unit

[0376] 110B: Multiplexer

[0377] 111: Receiver Amplifier

[0378] 112: A / D conversion circuit

[0379] 113: Frequency Analysis Department

[0380] 113A: Frequency Analysis Department

[0381] 113B: Frequency analysis unit

[0382] 120: Control department.

Claims

1. A position detector comprising: The coil is configured to function as a sensor, and includes a sending coil that sends an alternating magnetic field based on a sending signal to a position indicator; and The signal processing circuit is connected to the coil, detects the pen signal generated by the position indicator, generates the sending signal having a frequency based on the frequency information of the detected pen signal, and sends it to the sending coil.

2. The position detector according to claim 1, When the frequency of the pen signal generated by the position indicator changes with respect to the frequency of the detected pen signal, the signal processing circuit generates the transmission signal following the change in frequency.

3. The position detector according to claim 2, The signal processing circuit generates the transmission signal at a timing before the coordinate calculation process of the position indicator is started.

4. The position detector according to claim 3, The signal processing circuit generates the sending signal a plurality of times in one coordinate calculation process. The signal processing circuit continuously generates the transmission signal at the same frequency during the plurality of times of performing at least one of the coordinate calculation processes.

5. The position detector according to claim 1, The signal processing circuit performs frequency analysis on a plurality of discrete frequencies, and extracts, as a frequency, the discrete value closest to the peak value of the wave height value of the pen signal received from the position indicator among the discrete values ​​of frequency detection.

6. The position detector according to claim 5, When the frequency at which the wave height value of the pen signal received from the position indicator presents a peak value is inconsistent with the discrete value of the frequency detection, the signal processing circuit performs interpolation operation at the frequency at which the wave height value presents a peak value and the adjacent discrete value of the frequency detection to extract the frequency.

7. An integrated circuit for detecting a position indicated by a position indicator, wherein: The integrated circuit is connected to a coil, and the coil is configured so that a plurality of electrodes function as a sensor, and includes a sending coil that sends an alternating magnetic field based on a sending signal to the position indicator. The integrated circuit detects the pen signal generated by the position indicator, generates a transmission signal having a frequency based on frequency information of the detected pen signal, and transmits an alternating magnetic field to the position indicator via the coil.

8. A position detection method, which is a position detection method in a position detector, wherein: include: In a first step, the position detector sends a first signal to the position indicator; In a second step, the position indicator sends a second signal to the position detector; In a third step, the position detector detects frequency information from the second signal; a fourth step of generating, by the position detector, a third signal having a frequency different from that of the first signal based on the frequency information detected in the third step; and In a fifth step, the position detector transmits the third signal generated in the fourth step to the position indicator.

9. A position detector comprising: A detection coil configured to function as a sensor; A sending coil sends an alternating magnetic field based on a sending signal to a position indicator; and The signal processing circuit is connected to the detection coil and the sending coil, detects the pen signal generated by the position indicator, generates the sending signal having a frequency based on the frequency information of the detected pen signal, and sends it to the sending coil.

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