Method, position indicator and sensor controller

Abstract

A method, a position indicator, and a sensor controller are provided for obtaining a high bit rate at the same chip rate compared to the background technology that can only express one bit by one coding sequence. The sensor controller of the present invention is a sensor controller used in a position detector for detecting the position of a position indicator on a touch surface, and comprises: an MCU that outputs the value of a symbol to be sent to the position indicator; and a transmitting unit that generates a transmission signal including a chip sequence CN1 obtained by cyclically shifting a coding sequence PNa having an autocorrelation characteristic by a shift amount based on the value of the symbol to be sent, and transmits the generated transmission signal to the position indicator via the touch surface.

Description

[0001] This application is a divisional application of the application filed on January 18, 2018, with application number 201680042315.X and invention name “Sensor controller, position indicator and position detection system”. Technical Field

[0002] The present invention relates to a sensor controller, a position indicator and a position detection system, and in particular to a sensor controller for a position detector on which a position indicator is located on a touch surface, a position indicator configured to receive a signal sent by such a position detector, and a position detection system having the above-mentioned position detector and position indicator. Background Art

[0003] There is known a position detection system that enables communication between a position indicator that is a pen-shaped device and a position detector that is a device having a touch surface such as a tablet in both directions or in one direction from the position detector to the position indicator. Patent Document 1 discloses an example of the latter position detection system.

[0004] In addition, Patent Document 2 discloses an invention that uses a Direct Sequence Spread Spectrum (DSSS) method (hereinafter referred to as a direct spread method) in communication between a position indicator and a position detector constituting a position detection system.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2015 / 111159

[0008] Patent Document 2: U.S. Patent No. 7084860 Summary of the invention

[0009] Problems to be solved by the invention

[0010] As in the invention described in Patent Document 2, by using the direct spread method in the communication method between the position indicator and the position detector, a communication method with noise resistance can be realized.

[0011] For example, the transmitting side device can be configured to use a known coding sequence with an autocorrelation characteristic (a coding sequence in which a peak of the correlation value appears only when the shift amount is 0 when calculating the correlation value between the coding sequence and a coding sequence obtained by cyclically shifting the coding sequence or its inverse signal by an arbitrary shift amount) to encode each of the multiple bits (transmission bit string) constituting the transmission data.

[0012] Fig.16An example of a chip sequence generated by a transmitting device through encoding is shown. In the example shown in the figure, "00010010111" of 11 chips is used as a known coded sequence with autocorrelation characteristics. In addition, the transmitted bit string is "10110". As shown in the figure, when the value of the bit of the transmission object is "1", the above-mentioned coded sequence becomes the transmission chip sequence intact. On the other hand, when the value of the bit of the transmission object is "0", the inverse coded sequence of the above-mentioned coded sequence becomes the transmission chip sequence.

[0013] When the receiving device receives the transmission chip sequence sent by the transmitting device, it sequentially inputs each chip into a first-in-first-out type shift register having a capacity of 11 chips, and calculates the correlation value between the chip sequence of 11 chips temporarily stored in the shift register and the above-mentioned known code sequence each time the chip sequence is input. Since the above-mentioned code sequence has autocorrelation, when the chip sequence stored in the shift register is exactly "00010010111", the calculated correlation value becomes the maximum value (in this example, +11), and when the chip sequence stored in the shift register is exactly "11101101000" (the reverse code sequence of the known code sequence), the calculated correlation value becomes the minimum value (in this example, -11). On the other hand, the correlation value in other cases becomes a value close to 0 (in this example, +1 or -1). The receiving device is configured to extract the transmission data sent by the transmitting device from the received chip sequence by utilizing the characteristics of such correlation values.

[0014] However, in the communication method using the direct expansion method as described above, there is a problem that it is difficult to obtain a high bit rate. Fig.11 For example, 11 chips are required to represent 1 bit (binary value), so the bit rate can only be 1 / 11 of the chip rate. It is not easy to increase the chip rate, so it is difficult to obtain a high bit rate.

[0015] Therefore, one of the objects of the present invention is to provide a sensor controller, a position indicator, and a position detection system that can achieve a higher bit rate than the background art.

[0016] Solutions to Solve Problems

[0017] A sensor controller according to one aspect of the present invention is a sensor controller used in a position detector for detecting the position of a position indicator on a touch surface, and comprises: a control unit, which outputs the value of a symbol to be sent to the position indicator; and a sending unit, which generates a sending signal including a first code chip column obtained by cyclically shifting an extended code having an autocorrelation characteristic by a shift amount based on the value of the symbol to be sent, and sends the generated sending signal to the position indicator via the touch surface.

[0018] A position indicator according to one aspect of the present invention is a position indicator configured to receive a signal sent by a sensor controller via a position detector having a touch surface, and includes: a receiving unit that receives a signal and demodulates the value of a symbol contained in the signal based on a cyclic shift amount of a coding sequence having an autocorrelation characteristic contained in the signal, and restores the sent instruction based on the demodulation result; and a control unit that controls the sending of the signal to the sensor controller based on the instruction.

[0019] A position detection system according to one aspect of the present invention is a position detection system including a position indicator and a position detector for detecting the position of the position indicator on a touch surface, wherein the position detector comprises: a control unit for outputting the value of a symbol to be sent to the position indicator; and a sending unit for generating a sending signal including a first code chip sequence formed by cyclically shifting an extended code having an autocorrelation characteristic by a shift amount based on at least a part of the value of the symbol to be sent, and sending the generated sending signal to the position indicator via the touch surface, wherein the position indicator comprises a receiving unit for sequentially inputting a series of code chips generated by receiving the sending signal into a first-in-first-out type shift register, and calculating respective correlation values ​​between the code chip sequence temporarily accumulated in the shift register and a plurality of code sequences obtained by cyclically shifting a prescribed code sequence having an autocorrelation characteristic by an arbitrary shift amount at each input, thereby detecting a bit string contained in the series of code chips.

[0020] Effects of the Invention

[0021] According to the present invention, since cyclic shift of the code sequence is used in the generation of the chip sequence, more than 2 bits can be expressed by one code sequence. Therefore, compared with the background technology that can only express 1 bit by one code sequence, a higher bit rate can be obtained at the same chip rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a diagram showing the configuration of a position detection system 1 according to the first embodiment of the present invention.

[0023] Figure 2 Yes means Figure 1 The structure of the position detector 3 is shown in the figure.

[0024] Figure 3 (a) to (c) are diagrams showing examples of signals generated by the extension processing unit 63, respectively.

[0025] Figure 4 Yes means Figure 1 A block diagram of the functional blocks of the circuit unit 24 is shown.

[0026] Figure 5 It is used to describe the timing Figure 1 The timing chart of the operation of the stylus pen 2 and the sensor controller 31 is shown.

[0027] Figure 6 Yes means Figure 2 The block diagram of the functional blocks of the expansion processing unit 63 is shown.

[0028] Figure 7 Yes means Figure 6 A block diagram of the functional blocks of the control circuit 63a is shown.

[0029] Figure 8 is from Figure 6 FIG. 4 is an explanatory diagram of the chip sequence CN2 output by the shift register 63d.

[0030] Fig. 9 The solid line in (a) indicates Figure 8 The diagram of correlation values ​​between the coded sequence C1-0 and a coded sequence obtained by cyclically shifting the portion of the coded sequence C1-0 excluding the fixed chips NRa by an arbitrary shift amount is shown. Fig. 9 The dotted line in (a) indicates Figure 6 The diagram of the correlation value between the spread code PN and the code sequence obtained by cyclically shifting the spread code PN by an arbitrary shift amount is shown. Fig. 9 The solid line in (b) indicates Figure 8 The diagram of correlation values ​​between the code sequence C1-0 and the code sequence obtained by cyclically shifting the portion excluding the fixed chips NRa in the inverse coding by an arbitrary shift amount is shown. Fig. 9 The dotted line in (b) indicates Figure 6 The diagram shows the correlation values ​​between the extended code PN and the code sequence obtained by cyclically shifting the inverse code PN by an arbitrary shift amount.

[0031] Fig.10 is a diagram showing an example of the second control signal US_c2.

[0032] Fig.11 Yes means Figure 4 A block diagram of the functional blocks of the associated circuit 26b is shown.

[0033] Fig.12 In the first variant of the embodiment of the present invention, Figure 6 An illustration of the chip column CN2 output by the shift register 63d.

[0034] Fig.13 In the first variant of the embodiment of the present invention, Figure 6 An illustration of the chip column CN2 output by the shift register 63d.

[0035] Fig.14 2 is a block diagram showing functional blocks of a correlation circuit 26 b according to a second modification example of the embodiment of the present invention.

[0036] Fig.15 This is a timing chart for describing in time series the operations of the stylus pen 2 and the sensor controller 31 according to the third modified example of the embodiment of the present invention.

[0037] Fig.16 This is a diagram showing an example of a transmission code sequence generated by a position detector according to the background art of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0039] Figure 1 1 is a diagram showing a configuration of a position detection system 1 according to an embodiment of the present invention. The position detection system 1 includes a stylus pen 2 and a position detector 3 .

[0040] The stylus pen 2 is an active ES position indicator configured to receive signals sequentially sent by the position detector 3. Figure 1 As shown, it has a core 20, an electrode 21, a pen pressure detection sensor 23, a circuit unit 24, and a power source 25. As the power source 25, for example, a cylindrical AAAA battery is used. It should be noted that in this embodiment, an example in which the present invention is applied to the stylus pen 2 of the active ES method is described, but the present invention can also be well applied when using a stylus pen of other methods such as an electromagnetic induction method.

[0041] The core 20 is a rod-shaped member configured so that its length direction is consistent with the pen axis direction of the stylus pen 2. A conductive material is applied to the surface of the front end 20a of the core 20 to form an electrode 21. The rear end of the core 20 is in contact with the writing pressure detection sensor 23. The writing pressure detection sensor 23 is used to detect the pressure (writing pressure) applied to the front end 20a of the core 20.

[0042] The circuit unit 24 has the function of receiving the uplink signal US (the first control signal US_c1 and the second control signal US_c2) transmitted by the position detector 3 via the electrode 21, and transmitting the downlink signal DS (the position signal DS_pos and the data signal DS_res) toward the position detector 3 via the electrode 21. The above-mentioned signals will be described in detail later.

[0043] The position detector 3 includes a sensor 30 constituting a touch surface 3 a , a sensor controller 31 , and a main processor 32 that controls each part of the position detector 3 including the sensor 30 and the sensor controller 31 .

[0044] The sensor controller 31 has the functions of receiving downlink signals DS (position signal DS_pos and data signal DS_res) sent by the stylus pen 2 via the sensor 30 and sending uplink signals US (first control signal US_c1 and second control signal US_c2) toward the stylus pen 2 via the sensor 30 .

[0045] Figure 2 3 is a diagram showing the structure of the position detector 3. As shown in the figure, the sensor 30 has a structure in which a plurality of linear electrodes 30X and a plurality of linear electrodes 30Y are arranged in a matrix, and capacitive coupling is performed with the stylus pen 2 through the linear electrodes 30X and 30Y. In addition, the sensor controller 31 has a transmitting unit 60, a selecting unit 40, a receiving unit 50, a logic unit 70, and an MCU 80 (control unit).

[0046] The sending unit 60 is used to send Figure 1 The circuit of the uplink signal US (first control signal US_c1 and second control signal US_c2) shown in FIG. Specifically, it includes a first control signal supply unit 61, a switch 62, an extension processing unit 63, a coding column holding unit 64 and a transmission protection unit 65. It should be noted that, in particular, the first control signal supply unit 61 is described as a structure included in the transmission unit 60 in this embodiment, but it can also be included in the MCU 80.

[0047] The first control signal supply unit 61 holds the detection pattern c1 and has the function of following the instruction of the control signal ctrl_t1 supplied from the logic unit 70. Figure 5 The first control signal US_c1 is composed of the detection pattern c1 and the segmentation pattern STP output from the first control signal supply unit 61.

[0048] The detection pattern c1 is a pattern of symbol values ​​used by the stylus pen 100 to detect the presence of the sensor controller 31, and is known in advance by the stylus pen 100 (before the stylus pen 100 detects the sensor controller 31). The symbol is a unit of information used for modulation in the transmission process (a unit of information represented by the transmission signal), and is a unit of information obtained by demodulating 1 symbol as the received signal in the reception process. The symbol value can include a value converted into a bit string (hereinafter referred to as a "bit string corresponding value") and a value that is not converted into a bit string by the stylus pen 100 that receives the symbol (hereinafter referred to as a "bit string non-corresponding value"). As shown in Table 1 described later, the symbol for the former takes a value of the number of powers of 2, and can be associated with a bit string such as "0001". The bit length of each symbol marked by the bit string is determined according to the specification of the direct extension unit 63. On the other hand, the symbol for the latter takes a value of one or more (for example, two), and as shown in Table 1 described later, takes a value that is not associated with a bit string, such as "P" or "M". In an example shown in Table 1 described later, "P" and "M" are associated with a predetermined extended code sequence and its inverse code sequence, respectively.

[0049] The detection pattern c1 can be represented by a pattern of bit string non-corresponding values. For example, the detection pattern c1 can be formed by the repetition of two bit string non-corresponding values ​​“P” and “M”, such as “PMPMPM…”.

[0050] The partition pattern STP is a pattern of symbols used to notify the stylus 100 of the end of the above-mentioned continuous transmission period, and is composed of patterns of symbols that do not appear in the repetition of the detection pattern c1. For example, in the case where the detection pattern c1 is composed of the repetition of two bit string non-corresponding values ​​"P" and "M" as described above, such as "PMPMPM...", the partition pattern STP can be composed of a pattern "PP" composed of two consecutive bit string non-corresponding values ​​"P". It should be noted that the structure of the partition pattern STP and the detection pattern c1 can also be reversed, with the partition pattern being composed of "PM" and the detection pattern c1 being composed of "PP".

[0051] The switch 62 has a function of selecting either the first control signal supply unit 61 or the MCU 80 based on the control signal ctrl_t2 supplied from the logic unit 70, and supplying the output of the selected one to the expansion processing unit 63. When the switch 62 selects the first control signal supply unit 61, the detection pattern c1 or the division pattern STP is supplied to the expansion processing unit 63. On the other hand, when the switch 62 selects the MCU 80, the control information c2 is supplied to the expansion processing unit 63.

[0052] The control information c2 is information including instructions indicating the contents of instructions to the stylus pen 2, and is generated by the MCU 80. Fig.10The second control signal US_c2 shown is sent. The control information c2 includes the value of the symbol corresponding to the variable-length bit string (for example, 0 to 15), and the value is not shared with the stylus 2 in advance, which is different from the detection pattern c1. Moreover, the control information c2 is represented by the value "D" representing the number of powers of 2 (8 values) of the above-mentioned specified bit length, which is different from the detection pattern c1 containing the values ​​"P" and "M". The second control signal US_c2 is as shown Fig.10 As shown, a transmission signal (chip sequence) is transmitted with a division pattern STP "PP" as a leading code and then including three control information c2 represented by D1 to D3.

[0053] The code sequence holding unit 64 has a function of generating and holding an 11-chip-long extension code PN (second code sequence) having an autocorrelation characteristic based on a control signal ctrl_t3 supplied from the logic unit 70. The extension code PN held by the code sequence holding unit 64 is supplied to the extension processing unit 63. The specific contents of the extension code PN will be described later.

[0054] The extension processing unit 63 has a function of performing a primary modulation (cyclic shift or inversion described later) on the extension code PN held by the code sequence holding unit 64 based on the value of the symbol supplied via the switch 62 (information represented by the transmission signal after the processing of the extension processing unit 63), thereby obtaining a code sequence of 12 chips in length (Table 1, described later). Figure 6 The chip sequence CN2 shown in FIG. 2 is a function of the second chip sequence (a chip sequence acquisition function). The chip sequence acquisition function (primary modulation processing) will be described later. Figures 5 to 9 A more detailed description will be given below, but only an outline will be briefly described here.

[0055] The detection pattern c1, the division pattern STP, and the control information c2 of this embodiment are respectively composed of a combination of bit string corresponding values ​​0 to 15 (corresponding to bit strings "0000" to "1111") and bit string non-corresponding values ​​"P" and "M". Moreover, the extension code PN supplied from the extension code holding unit 64 is "00010010111".

[0056] In the primary modulation by the spreading processing unit 63, the values ​​of each symbol (0 to 15 and P and M) are converted into corresponding chip sequences CN2. Table 1 shows a specific example of the correspondence between the symbol values ​​and the generated chip sequences CN2 by the chip sequence acquisition function.

[0057] [Table 1]

[0058]

[0059] As shown in Table 1, one symbol represents multiple values, and the value of the symbol corresponds to any one of the chip sequences CN2 in Table 1 obtained by cyclically shifting the extended code PN by the shift amount based on the value of the symbol and making it non-inverted or inverted. The value of the symbol is any value ("0 to 15") among the values ​​of the number of powers of 2 (e.g., 16) represented by the bit string of a specified bit length, or one or more values ​​("P" or "M") different from the value of the number of powers of 2 that do not correspond to the bit string. The former is used for the transmission of control information c2, and the latter is used for the transmission of the division pattern STP such as the preamble.

[0060] When describing each row of the table in detail, the symbol value "P" is a bit string non-corresponding value, and is converted into a code sequence in which a fixed chip "1" is added to the beginning of the spread code PN "00010010111" having an autocorrelation characteristic. The bit string non-corresponding value "M" is converted into a code sequence in which a fixed chip "0" is added to the beginning of the inversion code "11101101000" which inverts the polarity of the spread code PN "00010010111".

[0061] The bit string corresponding values ​​0 to 7 are converted into code sequences in which "1" is added to the beginning of codes in which the extension code PN is cyclically shifted by the shift amounts shown in Table 1. For example, the symbol value "4" is converted into a code sequence in which "1" is added to the beginning of codes in which the extension code PN is cyclically shifted by 9 to the right (2 to the left). Moreover, the bit string corresponding values ​​8 to 15 are converted into code sequences in which "0" is added to the beginning of codes in which the inversion code "11101101000" after the polarity of the extension code PN is inverted and cyclically shifted by the value of the symbol by a specified shift amount. For example, the symbol value "12" is converted into a code sequence in which "1" is added to the beginning of codes in which the extension code PN is inverted and cyclically shifted by 9 to the right (2 to the left).

[0062] The difference between the nearest shift amount among the shift amounts of the bit string corresponding values ​​0 to 7 used for the instruction is 1. On the other hand, the difference between the shift amount of the symbol value "P" used in the division pattern STP of the preamble, etc. (i.e., 0) and the nearest value "0" (2 to the right) or "4" (2 to the left) of the shift amount used in the bit string corresponding values ​​0 to 7 of the instruction is 2, which is larger than the smallest difference among the differences in the shift amounts of the bit string corresponding values ​​0 to 7. In this way, the difference between the shift amount ("0") of the symbol values ​​"P" and "M" constituting the division pattern of the preamble, etc. and the shift amount (+2, -2) based on the values ​​("0", "4", "8", "12") constituting the instruction is larger than the smallest value among the shift amounts between a certain value constituting the instruction and other values ​​constituting the instruction, thereby reducing the probability of misjudging the division pattern of the preamble, etc. as any value among the prescribed values ​​corresponding to the instruction.

[0063] Here, the shift amount is determined so that the smaller the Hamming distance between a bit string corresponding to a certain symbol value and a bit string corresponding to another symbol value is, the smaller the difference between the shift amount of the certain symbol value and the shift amount of the other symbol value is. The reason why the shift amount is determined based on the Hamming distance between bit strings as shown in Table 1 instead of simply increasing the shift amount as the symbol value increases will be described later.

[0064] It should be noted that the transmitting unit 60 (the expansion processing unit 63 that has obtained the chip sequence CN2) may not directly use the obtained chip sequence CN2 as a transmission signal as shown in Table 1, but may also perform a process (secondary modulation process) of modulating a carrier signal based on the chip sequence CN2 to generate a transmission signal. The secondary modulation process is not necessarily required, but the secondary modulation process may include a process of performing Manchester encoding on the chip sequence CN2, etc.

[0065] Figure 3 (a) to (c) are diagrams showing examples of signals generated by the expansion processing unit 63. Each of these will be described below.

[0066] Figure 3 (a) is an example in which the spreading processing unit 63 does not perform secondary modulation processing. In this example, the chip sequence CN2 generated by the primary modulation becomes the transmission signal generated by the spreading processing unit 63 as it is.

[0067] Figure 3 (b) is an example in which the extension processing unit 63 performs only Manchester encoding as secondary modulation processing. In this case, the extension processing unit 63 assigns a rising edge to the "1" chip among the multiple chips included in the chip column CN2, and assigns a falling edge to the "0" chip, thereby obtaining the chip column CN2 after Manchester encoding. It should be noted that Manchester encoding of the chip column CN2 can also be performed by assigning a rising edge to the "0" chip and a falling edge to the "1" chip. Figure 3 In the example of (b), the chip sequence CN2 after Manchester coding becomes the transmission signal generated by the extension processing unit 63.

[0068] Figure 3 (c) is an example in which the spreading processing unit 63 performs Manchester encoding and digital modulation as secondary modulation processing. In this case, the spreading processing unit 63 modulates a predetermined carrier signal based on the chip sequence CN2 after Manchester encoding, thereby generating Figure 3 (c) shows the transmission signal. It should be noted that although Figure 3The example of a transmission signal generated according to BPSK (Binary Phase Shift Keying) is described, but other digital modulation methods can also be used. Figure 3 A sine wave signal is used as a carrier signal, but other types of carrier signals such as a rectangular wave signal may be used.

[0069] The secondary modulation process performed by the extension processing unit 63 includes Manchester coding, thereby Figure 3 (b) It can be seen that the same value no longer continues during a period longer than 1 chip. By performing secondary modulation on the transmission signal after spectrum expansion by the spreading code PN, for example, low frequency components can be avoided and the transmission can be performed using a desired frequency band.

[0070] return Figure 2 The transmission signal (first control signal US_c1 and second control signal US_c2) generated by the extension processing unit 63 is supplied to the transmission protection unit 65. The transmission protection unit 65 has a function of inserting a protection period between the transmission period of the first control signal US_c1 and the second control signal US_c2 and the reception period RDS described later based on the control signal ctrl_t4 supplied from the logic unit 70. The protection period is a period during which both transmission and reception are not performed in order to switch the transmission action and the reception action.

[0071] The selection unit 40 is a switch that switches between a transmission period in which a signal is transmitted from the sensor 30 and a reception period in which a signal is received by the sensor 30 based on the control of the logic unit 70. Specifically, the selection unit 40 includes switches 44x, 44y and conductor selection circuits 41x, 41y. The switch 44x operates based on a control signal sTRx supplied from the logic unit 70 so as to connect the output end of the transmission unit 60 to the input end of the conductor selection circuit 41x during the transmission period and to connect the output end of the conductor selection circuit 41x to the input end of the receiving unit 50 during the reception period. The switch 44y operates based on a control signal sTRy supplied from the logic unit 70 so as to connect the output end of the transmission unit 60 to the input end of the conductor selection circuit 41y during the transmission period and to connect the output end of the conductor selection circuit 41y to the input end of the receiving unit 50 during the reception period. The conductor selection circuit 41x operates to select one of the plurality of linear electrodes 30X and connect the selected linear electrode 30X to the switch 44x based on the control signal selX supplied from the logic unit 70. The conductor selection circuit 41y operates to select one of the plurality of linear electrodes 30Y and connect the selected linear electrode 30Y to the switch 44y based on the control signal selY supplied from the logic unit 70.

[0072] The receiving unit 50 is a circuit for detecting or receiving the position signal DS_pos and the data signal DS_res transmitted by the stylus pen 2 based on the control signal ctrl_r of the logic unit 70 . Specifically, the receiving unit 50 includes an amplifier circuit 51 , a detector circuit 52 , and an analog-to-digital (AD) converter 53 .

[0073] The amplifier circuit 51 amplifies and outputs the position signal DS_pos and the data signal DS_res supplied from the selection unit 40. The detector circuit 52 is a circuit that generates a voltage corresponding to the level of the output signal of the amplifier circuit 51. The AD converter 53 is a circuit that generates a digital signal by sampling the voltage output from the detector circuit 52 at a predetermined time interval. The digital data output by the AD converter 53 is supplied to the MCU 80.

[0074] The logic unit 70 and the MCU 80 are control units that control the transmission and reception operations of the transmission unit 60 and the reception unit 50. Specifically, the MCU 80 is a microprocessor that has a ROM and a RAM inside and operates based on a predetermined program. On the other hand, the logic unit 70 outputs the above-mentioned control signals based on the control of the MCU 80. The MCU 80 also plays the role of deriving coordinate data x, y, etc. indicating the position of the stylus pen 2 based on the digital data supplied from the AD converter 53, and outputting it to the main processor 32.

[0075] Figure 4 2 is a block diagram showing functional blocks of the stylus pen 2. As shown in the figure, the stylus pen 2 includes a switching unit SW, a receiving unit 26, a transmitting unit 27, and a control unit 28.

[0076] The switch SW is a switch that switches between receiving R and transmitting T based on the control signal SWC from the control unit 28. When receiving R, the electrode 21 is connected to the receiving unit 26, and when transmitting T, the electrode 21 is connected to the transmitting unit 27. In the initial state, that is, the pre-detection period BD (refer to Figure 5 ), the switching unit SW is set to receive R.

[0077] The receiving unit 26 is a circuit for receiving the signal supplied from the switching unit SW (the signal reaching the electrode 21) and obtaining the value of the sign from the transmission signal shown in Table 1, and is composed of a demodulation circuit 26a and a correlation circuit 26b. In order to reduce power consumption, the receiving unit 26 stops its operation except for the shortened reception period SRP during the pre-detection period BD before the sensor controller 31 is detected.

[0078] See also Figure 5For explanation, the receiving unit 26 performs the receiving action of the first control signal US_c1 for a shortened receiving period SRP (a time shorter than the period WPa, for example, 60μsec) every time a specified period WPa (for example, 2.5msec) occurs, and determines whether the first control signal US_c1 contains a pattern of symbol values ​​such as "PM" or "MP" that do not correspond to a bit string of a specified length, i.e., a detection pattern c1. The stylus 2 thereby attempts to detect the sensor controller 31. After detecting the sensor controller 31, the receiving unit 26 continues the receiving action to detect the division pattern STP, and receives the signal detected after the division pattern STP as the second control signal US_c2, and performs processing to extract therefrom the control information c2 composed of a value D corresponding to a bit string of a specified length.

[0079] Here, as described above, in the present embodiment, the division pattern STP is formed by two consecutive values ​​of the same symbol "PP". This is because the stylus pen 2 sometimes receives the signal from the position detector 3 by using its shell as an antenna instead of the electrode 21. In this case, each signal is supplied to the circuit unit 24 of the stylus pen 2 in a positive and negative inverted state, so the stylus pen 2 cannot normally receive the control information c2. Therefore, when detecting the division pattern STP, the stylus pen 2 not only monitors the symbol value "PP", but also monitors the symbol value "MM" composed of a chip column inverted from the chip column representing the symbol value "PP". And, in the case where the symbol value "PP" is detected, the control information c2 is attempted to be received by detecting the subsequent chip column as usual, and in the case where the symbol value "MM" is detected, the subsequent chip column is reversed after detection, thereby attempting to receive the control information c2. When determining whether the symbol value is inverted or not, the inversion or non-inversion of the first code chip column is used as a reference. Thus, even if the signal from the position detector 3 arrives via the shell rather than the electrode 21 and the polarity of the signal obtained through the electrode 21 is reversed, the stylus 2 will not make a mistake in determining the inversion or non-inversion of the polarity and can obtain the data constituting the control information c2.

[0080] The demodulation circuit 26a is a receiving circuit that generates a series of chips by receiving the signal sent by the position detector 3. Specifically, for example, if the position detector 3 performs Manchester encoding and digital modulation as secondary modulation processing, the demodulation circuit 26a performs the following processing: demodulates the signal guided to the electrode 21 by the modulation method used by the extension processing unit 63 of the position detector 3 to modulate the carrier signal, thereby obtaining a series of chips in sequence, and then decodes the series of chips in sequence by the inverse processing of Manchester encoding. The demodulation circuit 26a is configured to supply the series of chips obtained according to the decoding result to the correlation circuit 26b in the form of one chip. In the case where the extension processing unit 63 performs neither Manchester encoding nor digital modulation, the demodulation circuit 26a only needs to directly supply the series of chips received in sequence to the correlation circuit 26b in the form of one chip.

[0081] The correlation circuit 26b has a function of detecting the detection pattern c1, the division pattern STP, and the control information c2 included in a series of chips by performing correlation processing between a series of chips supplied from the demodulation circuit 26a and each of a plurality of known code sequences. Fig.11 When the detection pattern c1 is detected, the correlation circuit 26b issues an activation signal EN to the control unit 28. When the segmentation pattern STP is detected, the correlation circuit 26b outputs the detection time t2 to the control unit 28. When the control information c2 is detected, the correlation circuit 26b outputs the detected control information c2 to the control unit 28.

[0082] The control unit 28 is composed of a microprocessor (MCU), and is activated when the start signal EN is supplied from the receiving unit 26 (that is, when the receiving unit 26 detects the detection pattern c1), and performs various processes. Specifically, based on the detection time t2 supplied from the receiving unit 26, a transmission and reception schedule of each signal (control information c2, position signal DS_pos, and data signal DS_res) is generated, a control signal SWC based on the generated transmission and reception schedule is generated and supplied to the switching unit SW, and a transmission method of the data signal DS_res is controlled based on the control information c2 supplied from the receiving unit 26.

[0083] The control of the transmission method of the data signal DS_res is described in detail. When the content of the information to be transmitted (pen ID, pen pressure value, pressed state of the side switch, etc.) is specified by the control information c2, the control unit 28 controls the content of the information to be transmitted to the position detector 3 according to the specification. Specifically, the transmission data Res containing the information to be transmitted is generated and supplied to the transmission unit 27. Moreover, when the transmission timing of the data signal DS_res (for example, the time slot used for the transmission of the data signal DS_res) is specified by the control information c2, the timing of supplying the transmission data Res to the transmission unit 27 is controlled so that the data signal DS_res is transmitted at the transmission timing. Moreover, when the frequency used for the transmission of the data signal DS_res is specified by the control information c2, the modulation unit 27a described later is controlled to generate a carrier signal of the frequency.

[0084] It should be noted that when the receiving unit 26 does not detect the detection pattern c1, that is, when the receiving unit 26 has not received the supply of the next start signal EN after receiving the supply of the last start signal EN and completing the above-mentioned processing, the control unit 28 can stop the execution of the above-mentioned processing (that is, the processing of the control unit 28 is not executed). In this way, the power consumption of the control unit 28 can be reduced.

[0085] The transmission unit 27 is a circuit for transmitting the position signal DS_pos and the data signal DS_res, and is composed of a modulation unit 27a and a booster circuit 27b.

[0086] The modulation unit 27a is a circuit that generates a carrier signal (e.g., a rectangular wave signal) of a predetermined frequency or a frequency controlled by the control unit 28, and outputs it directly or after being modulated based on the control of the control unit 28. When the position signal DS_pos is transmitted, the modulation unit 27a does not modulate the carrier signal but directly outputs it. On the other hand, when the data signal DS_res is transmitted, the carrier signal is modulated by the transmission data Res supplied from the control unit 28, and the resulting transmission signal is output. As a specific modulation method used for this modulation, digital modulation methods such as PSK (Phase ShiftKeying) can be cited.

[0087] The boost circuit 27b is a circuit that generates a position signal DS_pos and a data signal DS_res by boosting the output signal of the modulation unit 27a to a certain amplitude. The position signal DS_pos and the data signal DS_res generated by the boost circuit 27b are sent from the electrode 21 to the space via the switching unit SW. It should be noted that the boost circuit 27b and the modulation unit 27a can also be implemented as one processing unit.

[0088] Figure 51 is a time chart for sequentially explaining the operation of the stylus pen 2 and the sensor controller 31. In the figure, the time axis shown in the upper section Ts represents the transmission Tx and reception Rx of the stylus pen 2. Also, the time axis shown in the lower section Tt represents the transmission Tx and reception Rx of the sensor controller 31.

[0089] The period until time t0 is a period when the stylus pen 2 is outside the detection range of the sensor controller 31. In order to reduce power consumption, the stylus pen 2 operates the receiving unit 26 intermittently and multiple times at a cycle WPa shorter than the continuous transmission period TCP. Specifically, in each cycle WPa, the receiving unit 26 is operated only during the shortened reception period SRP, and the receiving unit 26 is stopped at other times. The time length of the reception period SRP is set to a sufficient value required to receive the detection pattern c1 once.

[0090] The sensor controller 31 is configured to repeatedly transmit the first control signal US_c1 and the second control signal US_c2 at a period WP.

[0091] Specifically, the sensor controller 31 repeatedly transmits the chip sequence indicating the detection pattern c1 during a predetermined continuous transmission period TCP which is a time period longer than the period WPa, as the period WP starts.

[0092] Here, as described above, the detection pattern c1 of the present embodiment is "PMPMPMP..." In the position detector 3, the value P and the value M constituting the detection pattern c1 are respectively Figure 2 The chip sequence acquisition function of the extension processing unit 63 shown in the figure is used to convert the chip sequence CN2 into a chip sequence CN2 of 12 chips in length. The details will be described later.

[0093] The sensor controller 31 is configured to transmit a chip sequence representing the same symbol value P twice continuously just after the continuous transmission period TCP ends, thereby transmitting a segmentation pattern STP indicating the end of transmission of the detection pattern c1 (or the start of the second control signal US_c2). Figure 2 The chip sequence acquisition function of the extension processing unit 63 shown is used to convert the chips into 12-bit long chip sequences CN2 one by one. Up to now, the transmission of the first control signal US_c1 is completed.

[0094] After completing the transmission of the first control signal US_c1, the sensor controller 31 transmits a chip sequence representing control information c2 (ie, second control signal US_c2). The control information c2 is information that is transmitted after the division pattern STP as described above and includes an arbitrary bit string representing a command. Figure 4 The "D1", "D2", "D3", ... "Dn" shown in the figure represent the value D of any 4-bit bit string ("0000", "0001", etc.), respectively. Figure 2 The chip sequence CN2 is converted into a chip sequence CN2 of 12 chips in length by the chip sequence acquisition function of the extension processing unit 63 shown.

[0095] The sensor controller 31 that has completed the transmission of the second control signal US_c2 sets a reception period RDS for receiving a signal from the stylus pen 2. The stylus pen 2 is configured to transmit the position signal DS_pos within the reception period RDS when receiving the first control signal US_c1 transmitted as described above. The sensor controller 31 waits for the reception of the position signal DS_pos transmitted in this manner during the reception period RDS.

[0096] When the stylus pen 2 moves to the detection range of the sensor 30 (pen is put down) at time t0, the stylus pen 2 detects the detection pattern c1 transmitted by the sensor controller 31 at time t1 immediately after the reception period SRP in the continuous transmission period TCP.

[0097] The stylus pen 2 that detects the detection pattern c1 generates the above-mentioned start signal EN, and then continues the receiving action beyond the receiving period SRP. Furthermore, when the sensor controller 31 sends the partitioning pattern STP during the stylus pen 2's receiving action, the partitioning pattern STP is detected by the stylus pen 2. When the stylus pen 2 detects the partitioning pattern STP, it schedules the sending and receiving of the second control signal US_c2, the position signal DS_pos, and the data signal DS_res with reference to the time t2 when the detection is completed. Specifically, Figure 5 As shown, firstly, the reception of the second control signal US_c2 is waited for at the timing based on the time t2, then the position signal DS_pos is sent, and finally the data signal DS_res is sent.

[0098] As described above, the sensor controller 31 sets the reception period RDS after sending the second control signal US_c2, and waits for the reception of the position signal DS_pos. The sensor controller 31 receives the position signal DS_pos based on Figure 2 The position of the stylus pen 2 (coordinate data x, y) is calculated based on the reception status of the position signals DS_pos of the plurality of linear electrodes 30X and 30Y shown in FIG. Figure 1 The main processor 32 outputs and sets the receiving period RDS again, and waits for the reception of the data signal DS_res. The sensor controller 31 that has received the data signal DS_res extracts the transmission data Res from the received data signal DS_res and outputs it to the main processor 32.

[0099] After receiving the position signal DS_pos and the data signal DS_res from the stylus pen 2, the sensor controller 31 also repeatedly sends the first control signal US_c1 and the second control signal US_c2 as before. The stylus pen 2 thus repeatedly performs the above-mentioned operation. The sensor controller 31 receives the position signal DS_pos and the data signal DS_res from the stylus pen 2 each time the above-mentioned operation is performed, thereby calculating the position of the stylus pen 2 and obtaining the transmission data Res sent by the stylus pen 2.

[0100] The above is an overview of the position detection system 1. Figure 2 The chip sequence acquisition function of the extension processing unit 63 shown in FIG. Figure 3 In particular, the specific contents of the spreading code PN are also described in detail together with the description of the specific configuration example of the chip sequence acquisition function of the spreading processing unit 63 that obtains the transmission signal from the symbol value as described in Table 1.

[0101] Figure 6 Yes means Figure 2 1 is a block diagram of the functional blocks of the extension processing unit 63. As shown in the figure, the extension processing unit 63 is composed of a control circuit 63a, a code inversion / non-inversion switching circuit 63b (code sequence generating unit), a cyclic shifter 63c (cyclic shift unit), a shift register 63d (code chip sequence generating unit) and a modulation circuit 63e.

[0102] The code inversion / non-inversion switching circuit 63b has a function of generating a code sequence PNa (first code sequence) of 11 chips long having an autocorrelation characteristic based on the spread code PN (second code sequence) of 11 chips long stored in the code sequence holding unit 64. Specifically, according to the inversion information II supplied from the control circuit 63a, either the spread code PN or a code sequence obtained by inverting the spread code PN is selected, and the code sequence PNa is generated by the selected one.

[0103] Here, the spreading code PN is described in detail. As described above, the spreading code PN is a code sequence having an autocorrelation characteristic. Therefore, when the correlation value between the spreading code PN and the code sequence obtained by cyclically shifting the spreading code PN or its inverse signal by an arbitrary shift amount is calculated, the peak value of the correlation value appears only when the shift amount is 0. Fig. 9 , which illustrates the case where the extended code PN has an autocorrelation characteristic. It should be noted that, in the following, the extended code PN is set to "00010010111" for explanation.

[0104] Fig. 9The dotted line in (a) represents the correlation value between the spread code PN "00010010111" and the code sequence formed by cyclically shifting the spread code PN by an arbitrary shift amount. In the dotted line, for example, the correlation value when the shift amount is "+1" becomes the correlation value of the spread code PN "00010010111" and the code sequence "10001001011" formed by cyclically shifting each chip of the spread code PN by 1 to the right. And, for example, the correlation value when the shift amount is "-2" becomes the correlation value of the spread code PN "00010010111" and the code sequence "01001011100" formed by cyclically shifting each chip of the spread code PN by 2 to the left. It should be noted that in the calculation of the correlation value, "0" is treated as "-1".

[0105] in addition, Fig. 9 The dotted line in (b) indicates the correlation value of the code sequence formed by cyclically shifting the extended code PN "00010010111" and its inverse code "11101101000" by an arbitrary shift amount. In the dotted line, for example, the correlation value when the shift amount is "+1" is the correlation value of the extended code PN "00010010111" and the inverse code chips "01110110100" which is cyclically shifted to the right by one. And, for example, the correlation value when the shift amount is "-2" is the correlation value of the extended code PN "00010010111" and the inverse code chips "10110100011" which is cyclically shifted to the left by two.

[0106] exist Fig. 9 In either (a) or (b), the peak value of the correlation value indicated by the dotted line appears only when the shift amount is "0". Therefore, when the correlation value between the spreading code PN and the code sequence obtained by cyclically shifting the spreading code PN or its inverse signal by an arbitrary shift amount is calculated, it can be said that the peak value of the correlation value appears only when the shift amount is 0, and therefore it can be said that the spreading code PN has an autocorrelation characteristic.

[0107] return Figure 6 The code inversion / non-inversion switching circuit 63b also has the function of receiving the supply of the fixed code NR from the control circuit 63a, inverting or not inverting the fixed code NR according to the inversion information II supplied from the control circuit 63a, thereby generating the fixed code chip NRa. The fixed code NR is a code with a length of 1 code chip. Figure 6 In the example of , the fixed code NR is set to "1". Such a fixed code NR is used to make the bottom value (correlation value other than the peak value) of the correlation value of the chip sequence CN2 output from the shift register 63d described later become "0". This point will be described in detail later.

[0108] The cyclic shifter 63c is a functional unit that generates a chip sequence CN1 (first chip sequence) by cyclically shifting the code sequence PNa generated by the code inversion / non-inversion switching circuit 63b by the shift amount SA supplied from the control circuit 63a. Furthermore, the shift register 63d is a functional unit that receives the chip sequence CN1 generated by the cyclic shifter 63c and the fixed chips NRa generated by the code inversion / non-inversion switching circuit 63b in parallel, generates a chip sequence CN2 (second chip sequence) by adding the received fixed chips NRa to the received chip sequence CN1, and outputs the generated chip sequence CN2 in series.

[0109] Figure 8 1 is an explanatory diagram of the chip sequence CN2 output from the shift register 63d. The code sequence C1-0 shown in the figure is the chip sequence CN2 output from the shift register 63d when the code inversion / non-inversion switching circuit 63b does not perform inversion processing and does not perform cyclic shifting by the cyclic shifter 63c (the shift amount SA is "0"), and has a structure in which a fixed code NR "1" is added to the beginning of the extension code PN "00010010111". In addition, the code sequence C1-n is a code sequence obtained by cyclically shifting the chip sequence CN1 part of the code sequence C1-0 by the shift amount n, and represents the chip sequence CN2 output from the shift register 63d when the code inversion / non-inversion switching circuit 63b does not perform inversion processing and performs cyclic shifting by the cyclic shifter 63c by the shift amount n.

[0110] on the other hand, Figure 8 The code sequence C2-0 shown is a chip sequence CN2 output from the shift register 63d when the code inversion / non-inversion switching circuit 63b performs inversion processing and does not perform cyclic shifting by the cyclic shifter 63c (the shift amount SA is "0"), and is an inversion code of the code sequence C1-0. In addition, the code sequence C2-n is a code sequence obtained by cyclically shifting the chip sequence CN1 part of the code sequence C2-0 by the shift amount n, and represents the chip sequence CN2 output from the shift register 63d when the code inversion / non-inversion switching circuit 63b performs inversion processing and performs cyclic shifting by the cyclic shifter 63c by the shift amount n.

[0111] Refer again here Fig. 9 , Fig. 9 The solid line of (a) indicates Figure 8 The correlation value between the coded sequence C1-0 shown in FIG. 1 and the coded sequence obtained by cyclically shifting the portion of the coded sequence C1-0 excluding the fixed chips NRa by an arbitrary shift amount. Fig. 9 The solid line in (b) indicates Figure 8 The code sequence C1-0 shown is the same as the reverse code (i.e., Figure 8The correlation value of the coded sequence C2-0) shown in FIG. 1 is obtained by cyclically shifting the portion other than the fixed code chip NRa by an arbitrary shift amount. Fig. 9 In any of (a)(b), the peak value of the correlation value shown by the solid line appears only when the shift amount is "0", just like the example of the dotted line. Although not shown in the figure, the same can be said for all the coding sequences C1-n and C2-n. Therefore, the stylus pen 2 that receives the coding sequences C1-n and C2-n stores the coding sequences C1-n and C2-n in advance, and can detect the coding sequences C1-n and C2-n contained in the received code chip sequence by calculating the correlation value with the received code chip sequence. In the position detection system 1 of the present embodiment, this property is used to send and receive the first control signal US_c1 and the second control signal US_c2. Details on the detection action of the stylus pen 2 on the coding sequences C1-n and C2-n are described later.

[0112] It should be noted that if Fig. 9 As shown in (a), the bottom value of the correlation value (dashed line) calculated for the extended code PN is "-1", while the bottom value of the correlation value (solid line) calculated for the code sequence C1-0 is "0". Fig. 9 As shown in (b), the bottom value of the correlation value (dashed line) calculated for the inverse coding of the spreading code PN is "+1", while the bottom value of the correlation value (solid line) calculated for the inverse coding of the code sequence C1-0 is "0". The bottom value of the correlation value is "0" in this way because the fixed chip NRa is arranged at the beginning of the chip sequence CN2 so that the number of positive chips is the same as the number of negative chips. In other words, the bottom value of the correlation value is "0" by arranging the fixed chip NRa at the beginning of the chip sequence CN2.

[0113] When the fixed chip NRa is not attached to the spread code PN, the distance between the bottom value "-1" of the correlation value and the maximum value "+11" is 10. On the other hand, when the fixed chip NRa is attached to the spread code PN, the distance between the bottom value "0" of the correlation value and the maximum value "+12" is 12. Therefore, it can be said that by attaching the fixed chip NRa to the spread code PN and setting the bottom value to "0", it can be said that the determination error on the receiving side can be reduced. Therefore, according to the position detector 3 of this embodiment, from this point of view, the possibility of making a determination error on the stylus pen 2 side can also be reduced.

[0114] return Figure 6The modulation circuit 63e performs secondary modulation processing for generating a transmission signal constituting the first control signal US_c1 or the second control signal US_c2 based on the chip sequence CN2 generated by the shift register 63d. The details of the secondary modulation processing are as described above. The transmission signal generated by the modulation circuit 63e through the secondary modulation processing is transmitted via Figure 2 The transmission protection unit 65 and the selection unit 40 shown in FIG. 4 reach the sensor 30, and pass through the sensor 30 via the touch surface 3a (refer to FIG. 4 ). Figure 1 ) is sent to stylus 2.

[0115] The control circuit 63a is a functional unit that controls the operation of each unit within the expansion processing unit 63. As part of its functions, it has the function of generating a fixed code NR and inversion information II and supplying them to the code inversion / non-inversion switching circuit 63b, and the function of generating a shift amount SA and supplying it to the circular shifter 63c.

[0116] Figure 7 1 is a block diagram showing a portion of the functional blocks of the control circuit 63a related to the generation of the inversion information II and the shift amount SA. As shown in the figure, the control circuit 63a functionally includes an input receiving unit 100, an inversion information determination unit 101, a shift amount determination unit 102, a shift amount / inversion information storage unit 103, and an output selection unit 104.

[0117] The input receiving unit 100 is Figure 2 The switch 62 shown is a functional unit for accepting inputs of the values ​​P, M, and D constituting the detection pattern c1, the division pattern STP, and the control information c2. When the input accepting unit 100 accepts an input of a value P or a value M that does not correspond to a specific bit string, it supplies the accepted value to the output selection unit 104. On the other hand, when the input of the value D of the bit string (here, 4 bits long) is accepted, the most significant bit is supplied to the inversion information determination unit 101 as the inversion information indication bit IIIB (the second bit string of 1 bit length to be sent to the stylus pen 2), and the remaining part (3 bits) is supplied to the shift amount determination unit 102 as the shift amount indication bit string SAIB (the first bit string of 2 or more specified bit lengths to be sent to the stylus pen 2).

[0118] The inversion information determination unit 101 is a functional unit that determines the first inversion information II1 based on the inversion information indication bit IIIB supplied from the input receiving unit 100. Specifically, the inversion information determination unit 101 stores an inversion allocation table 101a shown in Table 2 below, and determines the first inversion information II1 according to the inversion allocation table 101a. The first inversion information II1 thus determined is supplied to the output selection unit 104.

[0119] [Table 2]

[0120] Inversion information indication bit IIIB First reverse information II1 0 No reversal 1 There is a reversal

[0121] The shift amount determination unit 102 is a functional unit that determines the first shift amount SA1 based on the shift amount indication bit sequence SAIB supplied from the input receiving unit 100. Specifically, the shift amount determination unit 102 stores a shift amount allocation table 102a shown in Table 3 below, and determines the first shift amount SA1 based on the shift amount allocation table 102a. The first shift amount SA1 thus determined is supplied to the output selection unit 104.

[0122] [Table 3]

[0123] Shift amount indication bit string SAIB The first shift amount SA1 000 2 001 3 011 4 010 5 110 6 111 7 101 8 100 9

[0124] As can be seen from Table 3, the shift amount determination unit 102 of the present embodiment first determines the value "2" as the first shift amount SA1 for the bit string "000" (predetermined reference bit string). The value called "2" becomes the value "2" obtained by adding the predetermined value (=2) to the second shift amount SA2 (=0) described later. And, for each of the plurality of bit strings that are sequentially incremented from the bit string "000" according to the predetermined reference, the value obtained by adding the first shift amount SA1 (=2) determined for the bit string "000" to the number of increments is determined as the first shift amount SA1. It should be noted that the predetermined reference mentioned here is the case where the Hamming distance between the bit string before the increment and the bit string after the increment is 1. The significance of adopting such a reference will be described later.

[0125] For example, the bit string obtained by incrementing the bit string "000" three times according to the above-specified benchmark is "010", and the first shift amount SA1 assigned to the bit string "010" becomes "5" (=2+3) obtained by adding the number of increments 3 to the first shift amount SA1 (=2) determined for the bit string "000".

[0126] The shift amount / reversal information storage unit 103 stores the values ​​of the second reversal information II2, the second shift amount SA2, the third reversal information II3, and the third shift amount SA3. Specifically, "no reversal" is stored as the second reversal information II2, "0" is stored as the second shift amount SA2, "reversal" is stored as the third reversal information II3, and "0" is stored as the third shift amount SA3.

[0127] In response to the value P being supplied from the input receiving unit 100, the output selecting unit 104 uses the second inversion information II2 and the second shift amount SA2 stored in the shift amount / inversion information storing unit 103 as the inversion information II and the shift amount SA, respectively, to output the value P to the output selecting unit 104. Figure 6 The coding inversion / non-inversion switching circuit 63b and the circular shifter 63c shown are provided. Figure 6 The shift register 63d shown outputs Figure 8 The coded sequence C1-0 shown is used as the chip sequence CN2. In addition, in response to the supply of the value M from the input receiving unit 100, the output selection unit 104 uses the third inversion information II3 and the third shift amount SA3 stored in the shift amount / inversion information storage unit 103 as the inversion information II and the shift amount SA, respectively. Figure 6 The coding inversion / non-inversion switching circuit 63b and the circular shifter 63c shown are provided. Figure 6 The shift register 63d shown outputs Figure 8 The coded sequence C2-0 is shown as the chip sequence CN2.

[0128] On the other hand, in response to the case where neither the value P nor the value M is supplied from the input receiving unit 100 (i.e., the case where the value D is input to the input receiving unit 100), the output selecting unit 104 outputs the first inversion information II1 determined by the inversion information determining unit 101 as the inversion information II. Figure 6 The coding inversion / non-inversion switching circuit 63b shown in FIG. 1 is supplied and the first shift amount SA1 determined by the shift amount determination unit 102 is used as the shift amount SA to Figure 6 The circular shifter 63c shown is provided. Thus, Figure 6 The shift register 63d shown outputs Figure 8 Any one of the coded columns C1-2 to C1-9 and C2-2 to C2-9 shown is used as the chip column CN2. More specifically, when the inversion information II is "no inversion", the coded column C1-SA is output, and when the inversion information II is "inversion", the coded column C2-SA is output. It should be noted that Figure 8 The diagram also shows the correspondence between the 4-bit bit string received by the input receiving unit 100 and the chip string CN2 output by the shift register 63d. For example, when the bit string received by the input receiving unit 100 is "0010", the chip string CN2 output by the shift register 63d becomes the code string C1-5, that is, "110111000100". Furthermore, when the bit string received by the input receiving unit 100 is "1010", the chip string CN2 output by the shift register 63d becomes the code string C2-5, that is, "001000111011".

[0129] In this way, the transmitting unit 60 can generate a transmission signal including a chip sequence CN2 obtained by cyclically shifting the spread code PN having an autocorrelation characteristic by a shift amount based on the value of the symbol to be transmitted, and inverting (or not inverting) it when necessary, as shown in the aforementioned Table 1. It should be noted that the order of the cyclic shift processing and the inversion and non-inversion processing in the transmitting unit 60 is arbitrary as long as the chip sequence CN2 can be obtained as shown in Table 1. In addition, the transmitting unit 60 can store the correspondence between the symbol value and the chip sequence CN2 or the transmission signal including the chip sequence CN2 in advance in a memory, and read the chip sequence CN2 stored in the memory and transmit it every time the value of the symbol is input.

[0130] Fig.10 2 is a diagram showing the second control signal US_c2 sent by the position detector 3 to the stylus pen 2. In the example of the figure, after the position detector 3 sends the value P constituting the division pattern STP as a preamble twice in a row, it sends three values ​​D1 "0" (0b0000), D2 "8" (0b1000), and D3 "6" (0b0110) as control information c2. When sending the value P, the output from the shift register 63d is Figure 8 The coded sequence C1-0 shown in the figure, that is, "100010010111", is used as the chip sequence CN2. On the other hand, when sending the control information c2, the chip sequence CN2 is generated according to the 4-bit values ​​D1, D2, and D3. In this case, for the first 4-bit value D1, the corresponding bit string is "0000", and the chip sequence CN2 is generated. Figure 8 The code sequence C1-2 shown, that is, "111000100101", is used as the chip sequence CN2. As for the next 4-bit bit string D2, since its content is "1000", it generates Figure 8 The code sequence C2-2 shown, that is, "000111011010", is used as the chip sequence CN2. As for the last 4-bit bit string D3, since its content is "0110", it generates Figure 8 The code sequence C1-6, i.e., "101011100010", is shown as the chip sequence CN2.

[0131] It should be noted that, for example, a part or all of the bit string D3, which is the last 1 value (4-bit value) of the control information c2, may be composed of an error correction code calculated based on the bit strings D1 and D2 located before it. Thus, the stylus pen 2 on the receiving side can use the error correction code to detect or correct the bit errors generated in the bit strings D1 and D2.

[0132] Here, the significance of using the criterion that "the Hamming distance between the bit sequence before increment and the bit sequence after increment is 1" as the above-mentioned criterion for determining the first shift amount SA1 is explained. When the stylus pen 2 receives the chip sequence CN2, there is a case where the stylus pen 2 receives the chip sequence CN2 in a state where the shift amount deviates from 1. For example, although the position detector 3 sends Figure 8 In the example, the coding sequence C1-6 shown in the figure is judged as coding sequence C1-7 by the stylus 2. In order to correct such an erroneous judgment by using the above-mentioned error correction coding, the smaller the difference between the bit string represented by the coding sequence C1-6 and the bit string represented by the coding sequence C1-7, the better. In the present embodiment, by adopting the above-mentioned prescribed benchmark, the bit string represented by the coding sequence C1-6 is "0110", and the bit string represented by the coding sequence C1-7 is "0111", and the difference is only 1 bit. Therefore, even in the case of an erroneous judgment, it is only a difference of 1 bit. When the instruction is sent, the error correction can be performed by implementing the error correction coding that can perform 1-bit correction. In this way, by adopting the benchmark such as "the Hamming distance between the bit string before increment and the bit string after increment is 1" as the above-mentioned prescribed benchmark, a signal that is robust to erroneous judgment of the shift amount can be sent by adding the error correction coding.

[0133] Next, Fig.11 Yes means Figure 4 As shown in the figure, the correlation circuit 26b includes a shift register 110, a code sequence storage unit 111, a detection pattern detection unit 112, a division pattern detection unit 113 (preamble detection unit), a bit string detection unit 114, and an instruction restoration unit 115.

[0134] The shift register 110 is a first-in-first-out register that receives a series of chips received by the demodulation circuit 26a one chip at a time, and is configured to store chips for 12 chips. When chips exceeding 12 chips are input, the chips are deleted in order from the oldest chips.

[0135] The code sequence storage unit 111 stores a plurality of code sequences obtained by cyclically shifting a predetermined code sequence having an autocorrelation characteristic by an arbitrary shift amount. Specifically, the code sequences that the code sequence storage unit 111 needs to store are all the code sequences that the position detector 3 may send. Therefore, the code sequence storage unit 111 of this embodiment only needs to store Figure 8 The code sequences shown may be C1-0, C1-2 to C1-9, C2-0, C2-2 to C2-9.

[0136] The detection pattern detection unit 112 has a timer (not shown) inside, and the timer indicates the current time. Figure 5In the case of the reception period SRP shown in FIG. 1 , a functional unit performs a detection operation of the detection pattern c1 included in a series of chips output from the demodulation circuit 26a. Specifically, as this detection operation, each time a new chip is input to the shift register 110, the correlation value between the chip sequence temporarily accumulated in the shift register 110 and the code sequence corresponding to the values ​​P and M constituting the detection pattern c1, specifically, the code sequence C1-0 and the code sequence C2-0 among the plurality of code sequences stored in the code sequence storage unit 111 is calculated. And, when the correlation value with the code sequence C1-0 indicates a peak value, it is determined that the value P is detected, and when the correlation value with the code sequence C2-0 indicates a peak value, it is determined that the value M is detected. The detection pattern detection unit 112 determines that the detection pattern c1 is detected when the value P and the value M are detected alternately and continuously for a predetermined number of times, and issues the above-mentioned start signal EN to the control unit 28.

[0137] The division pattern detection unit 113 is a functional unit that starts the detection operation of the division pattern STP (preamble code) included in a series of chips output from the demodulation circuit 26a according to the detection pattern detection unit 112 detecting the detection pattern c1. As this detection operation, specifically, each time a new chip is input to the shift register 110, the correlation value between the chip sequence temporarily accumulated in the shift register 110 and the code sequence corresponding to the value P constituting the division pattern STP, specifically the code sequence C1-0, among the multiple code sequences stored in the code sequence storage unit 111 is calculated. And, when the correlation value calculated in this way indicates a peak value, it is determined that the value P is detected. The division pattern detection unit 113 determines that the division pattern STP is detected according to the situation that the value P is detected twice in a row, stops the detection operation, and outputs the above-mentioned detection time t2 to the control unit 28.

[0138] The bit string detection unit 114 is a functional unit that performs a detection operation of a value D (bit string of 4 bits) included in a series of chips output from the demodulation circuit 26a at a timing indicating the reception period of the control information c2 by the transmission and reception schedule generated by the control unit 28. Specifically, as this detection operation, each time a new chip is input to the shift register 110, the chip string temporarily accumulated in the shift register 110 and the code string corresponding to the value D among the plurality of code strings stored in the code string storage unit 111, specifically, the code strings C1-2 to C1-9 and C2-2 to C2-9 are calculated. And, when the correlation value calculated in this way indicates a peak value, it is determined that the value D (bit string of 4 bits) corresponding to the code string indicating the peak value is detected. Each time D is detected, the bit string detection unit 114 outputs the bit string as the detected value D to the instruction restoration unit 115.

[0139] The command restoration unit 115 is a functional unit that restores the control information c2 sent from the position detector 3 by combining the bit strings sequentially supplied from the bit string detection unit 114. The command restoration unit 115 outputs the restored control information c2 to the control unit 28. In this way, the command sent from the position detector 3 is supplied to the control unit 28.

[0140] As described above, according to the position detector 3 and the stylus pen 2 of the present embodiment, since the cyclic shift of the code sequence is used in the generation of the chip sequence CN2 sent by the position detector 3, more than 2 bits can be expressed by one code sequence. Therefore, compared with the background technology that can only express 1 bit by one code sequence, a higher bit rate can be obtained at the same chip rate.

[0141] Furthermore, since the chip sequence CN2 is formed by adding the fixed chip NRa to the chip sequence CN1, it is possible to reduce detection errors on the receiving side, thereby reducing the possibility of a reception error on the stylus pen 2 side.

[0142] In addition, for each of the plurality of bit strings formed by sequentially increasing from a prescribed reference bit string through a prescribed reference, a value obtained by adding the number of increments to the first shift amount SA1 determined for the reference bit string is determined as the first shift amount SA1, and a reference such as "the Hamming distance between the bit string before the increment and the bit string after the increment is 1" is adopted as the prescribed reference. Therefore, even if the chip sequence CN2 is received in a state where the shift amount deviates from 1, the error correction caused by the misjudgment of the shift amount can be suppressed to a 1-bit error, thereby achieving such an effect by a shorter error correction code.

[0143] As mentioned above, although the preferred embodiment of the present invention was described, the present invention is not limited to such embodiment at all, and the present invention can be implemented in various forms without departing from the scope of the present invention.

[0144] For example, in the above embodiment, 11 bits "00010010111" are used as the spread code PN, but any code sequence can be used as the spread code PN as long as it has an autocorrelation characteristic. In addition, one spread code PN is used to transmit the value of one symbol, but the value of one symbol may include multiple (for example, 5) identical chip sequences CN2. In this case, it is equivalent to transmitting the value of the same symbol multiple times (for example, 5 times), and the erroneous determination of the shift amount can be further reduced by selecting the shift amount that is most desired to be confirmed among the multiple shift amounts.

[0145] Table 4 and Table 5 and Fig.12 and Fig.13 In the first variation of the above embodiment, Figure 6An illustration of the chip column CN2 output by the shift register 63d.

[0146] [Table 4]

[0147]

[0148] [Table 5]

[0149]

[0150] In this modification, a 31-bit bit string "0000100100011011011110001010111" is used as the spread code PN. This spread code PN also has an autocorrelation characteristic similar to the 11-bit spread code PN used in the above embodiment.

[0151] In this modification, the shift amount allocation table 102a is constructed as the following Table 6. The difference between Table 6 and the shift amount allocation table 102a shown in Table 3 is that the first shift amount SA1 determined for the reference bit string "000" is not "2" but "5" (a value obtained by adding 5 to the second shift amount SA2 (=0)); and the number added to the first shift amount SA1 (=5) is not the number of increments itself, but a number corresponding to the number of increments (specifically, 3 times the number of increments). The inversion allocation table 101a and the second inversion information II2 and the second shift amount SA2 values ​​stored in the shift amount / inversion information storage unit 103 are the same as those shown in the above embodiment.

[0152] [Table 6]

[0153]

[0154] In this modification, Fig.12 The code column C3-0 shown corresponds to the value P, Fig.13 The code column C4-0 shown corresponds to the value M, Fig.12 The code columns shown are C3-5, C3-8, C3-11, C3-14, C3-17, C3-20, C3-23, C3-26 and Fig.13The coded sequences C4-5, C4-8, C4-11, C4-14, C4-17, C4-20, C4-23, and C4-26 shown correspond to bit strings of 4 bits in length, respectively. It should be noted that the coded sequence C3-0 is a structure in which a fixed code NR "1" is added to the beginning of the extended code PN "0000100100011011011110001010111", the coded sequence C3-n is a structure in which only the portion of the coded sequence C3-0 corresponding to the chip sequence CN1 is cyclically shifted by a shift amount n, the coded sequence C4-0 is an inverse code of the coded sequence C3-0, and the coded sequence C4-n is a structure in which only the portion of the coded sequence C4-0 corresponding to the chip sequence CN1 is cyclically shifted by a shift amount n.

[0155] In this way, even if a longer extended code PN is used, multiple values ​​of more than 2 bits can be expressed by one transmission signal, as in the above-mentioned embodiment. The extended code PN is long, and the bit rate decreases accordingly, but on the other hand, the difference in the shift amount between adjacent code columns can be obtained to a greater extent, so the possibility of the stylus 2 erroneously judging and detecting the shift amount (the value of the corresponding symbol) can be reduced. For example, even in the case where the shift amount to the right is detected to be +6, by making the value that is judged to be +5 to the right "0", the error in the shift amount can be reliably decoded. Moreover, by setting the shift amount to an odd number greater than 3 as in the modified example, for example, when the shift amount to the right is detected to be +7, the value that is +8 to the right is "1", and when the shift amount to the right is detected to be +5, the value that is +5 to the right is "0", etc., the same discrete amount redundancy can be achieved when judging the shift amount, which is preferred.

[0156] In the above-mentioned modification, the difference between the nearest shift amounts among the shift amounts of the bit string corresponding values ​​0 to 7 used for the instruction is also 3. On the other hand, the difference between the shift amount of the symbol value "P" used in the preamble code division pattern STP (i.e., 0) and the nearest value "0" (5 to the right) or "4" (5 to the left) among the shift amounts of the bit string corresponding values ​​0 to 7 used for the instruction is 5, which is larger than the difference of 3 in the shift amount of the bit string corresponding values ​​0 to 7. In this way, the smallest difference (5) among the differences between the shift amounts of the symbol values ​​"P" and "M" used in the preamble code division pattern and the shift amounts based on the values ​​constituting the instruction is larger than the smallest value (3) among the differences between the shift amounts based on one value constituting the instruction and the shift amounts based on another value, thereby reducing the probability of misjudging the preamble code division pattern as any value among the prescribed values ​​corresponding to the instruction.

[0157] In the above embodiment, the inverse processing of Manchester coding is performed in the demodulation circuit 26a of the stylus pen 2. However, when the expansion processing unit 63 of the position detector 3 performs Manchester coding, the inverse processing of Manchester coding may not be performed in the demodulation circuit 26a. Fig.14 Provide explanation.

[0158] Fig.14 2 is a block diagram showing the functional blocks of the related circuit 26b of the second modified example of the above-mentioned embodiment. As shown in the figure, the related circuit 26b of this modified example replaces Fig.11 The shift register 110, detection pattern detection unit 112, division pattern detection unit 113 (preamble detection unit) and bit string detection unit 114 shown are also composed of a shift register 120, Manchester encoding unit 121, detection pattern detection unit 122, division pattern detection unit 123 (preamble detection unit) and bit string detection unit 124.

[0159] The shift register 120 is different from the shift register 110 of the above embodiment which can store only 12 chips in that it is configured to store 24 chips. This is because the demodulation circuit 26a does not perform the inverse process of Manchester coding, so the number of chips to be input to the shift register 120 for one chip sequence CN2 increases to 24.

[0160] The Manchester encoding unit 121 is a functional unit that performs Manchester encoding on the code sequence when supplying the code sequence stored in the code sequence storage unit 111 to the detection pattern detection unit 122, the division pattern detection unit 123, and the bit sequence detection unit 124. Therefore, the Manchester-encoded code sequence is supplied to the detection pattern detection unit 122, the division pattern detection unit 123, and the bit sequence detection unit 124.

[0161] The detection pattern detection unit 122, the division pattern detection unit 123, and the bit string detection unit 124 calculate the correlation value between the 24-chip-long chip sequence temporarily accumulated in the shift register 120 and the 24-chip-long code sequence in the Manchester-coded state, and are different from the detection pattern detection unit 112, the division pattern detection unit 113, and the bit string detection unit 114 in this point. In other points, they are the same as the detection pattern detection unit 112, the division pattern detection unit 113, and the bit string detection unit 114.

[0162] Here, the Manchester-encoded state usually does not show Fig. 9However, since the peak value can be detected, the detection pattern detection unit 122, the division pattern detection unit 123 and the bit string detection unit 124 can respectively detect the detection pattern c1, the division pattern STP and the 4-bit long bit string through the above processing.

[0163] In addition, in the above-mentioned embodiment, the position detector 3 is described as follows. Figure 5 The situation shown in the figure is that the second control signal US_c2 is sent following the first control signal US_c1, but the second control signal US_c2 (specifically, the chip column CN2 corresponding to the control information c2) may be sent after a specified time greater than 0 has passed after the first control signal US_c1 (specifically, the chip column CN2 corresponding to the division pattern STP) has been sent.

[0164] Fig.15 1 is a timing chart for sequentially explaining the operation of the stylus pen 2 and the sensor controller 31 of the third modified example of the above embodiment. The position detector 3 shown in the figure does not send the second control signal US_c2 after the first control signal US_c1, but sets a reception period RDS of a predetermined time length WT after the first control signal US_c1 is sent, and sends the second control signal US_c2 only when the position signal DS_pos is received, which is different from the position detector 3 of the above embodiment. In this way, even if an interval is set between the first control signal US_c1 and the second control signal US_c2, as long as the time length of the interval is predetermined, the stylus pen 2 can determine the above-mentioned transmission and reception schedule in consideration of the interval, and can therefore receive the second control signal US_c2 without any problem.

[0165] In the above embodiment, one chip sequence CN2 is allocated to four bits, but the number of bits that can be allocated to one chip sequence CN2 is not limited to four. Fig.12 and Fig.13 In the case of a long code sequence as shown, more bits can be expressed by one code sequence.

[0166] In the above embodiment, the detection pattern c1 and the division pattern STP are expressed by the dedicated code sequences C1-0 and C2-0, but they can also be expressed by the same structure as the code sequence for the bit string. In the case where the code sequences C1-0 and C2-0 are set as dedicated to the detection pattern c1 and the division pattern STP, Figure 8 As shown, by making the difference in shift amount (in Figure 82) is greater than the difference in shift amount between the coding sequences C1-n (or coding sequences C2-n) (n≠1) (in Figure 8 1), the detection errors of the detection pattern c1 and the division pattern STP can be reduced, and on the other hand, the coding sequence used for sending the bit string is reduced. By using the same structure as the coding sequence used for the bit string as the division pattern STP as described above, the effect of increasing the coding sequence used for sending the bit string can be obtained.

[0167] In the above embodiment, the structure in which the fixed chip NRa is added to the chip sequence CN1 is used as the chip sequence CN2. However, if the noise caused by the bottom value of the correlation value not being "0" does not become a problem, the chip sequence CN1 may be directly used as the chip sequence CN2.

[0168] In the above embodiment, the chip sequence CN2 is formed by adding the fixed chip NRa to the beginning of the chip sequence CN1. However, the chip sequence CN2 may be formed by adding the fixed chip NRa to the end of the chip sequence CN1.

[0169] In the above embodiment, an example of sending the detection pattern c1 before the division pattern STP is described, but when the stylus pen 2 can perform the receiving operation continuously rather than intermittently, the sending of the detection pattern c1 can be omitted. In this case, the stylus pen 2 detects the position detector 3 by detecting the division pattern STP.

[0170] Furthermore, in the above embodiment, an example in which the present invention is applied to a signal transmitted from the position detector 3 to the stylus pen 2 is described, but the present invention can also be applied to a signal transmitted from the stylus pen 2 to the position detector 3 .

[0171] In addition, in the above-mentioned embodiment, a coding inversion / non-inversion switching circuit 63b and a circular shifter 63c are provided in the extension processing unit 63, and inversion and circular shift of the coding column are performed in the extension processing unit 63. However, the extension processing unit 63 may also be configured such that the value of a symbol that may be input to the control circuit 63a and the chip column CN2 to be output are preliminarily associated and stored in a storage area, and the chip column CN2 corresponding to the value of the input symbol is taken out from the storage area, thereby generating the chip column CN2.

[0172] Explanation of symbols

[0173] 1 Position detection system

[0174] 2 Stylus

[0175] 3 Position detector

[0176] 3a Touch surface

[0177] 20 cores

[0178] 20a Front end

[0179] 21 Electrode

[0180] 23 Pen pressure detection sensor

[0181] 24 Circuit Department

[0182] 25 Power Supply

[0183] 26 Receiving Department

[0184] 26a Demodulation circuit

[0185] 26b Related circuits

[0186] 27 Sending Department

[0187] 27a Modulation unit

[0188] 27b Boost Circuit

[0189] 28 Control Department

[0190] 30 Sensors

[0191] 30X, 30Y Linear Electrode

[0192] 31 Sensor Controller

[0193] 32 Main processor

[0194] 40 Selection Department

[0195] 41x, 41y conductor selection circuit

[0196] 44x, 44y switch

[0197] 50 Receiving Department

[0198] 51 Amplifier circuit

[0199] 52 Detection circuit

[0200] 53 Analog-to-digital converter

[0201] 60 Sending Department

[0202] 61 Control signal supply unit

[0203] 62 Switch

[0204] 63 Extended Processing Unit

[0205] 63a Control circuit

[0206] 63b Code inversion / non-inversion switching circuit

[0207] 63c Circular Shifter

[0208] 63d Shift Register

[0209] 63e Modulation Circuit

[0210] 64 Code sequence holding unit

[0211] 65 Send Protection Department

[0212] 70 Logic Department

[0213] 80 MCU

[0214] 100 Input Acceptance Department

[0215] 101 Reversal information determination unit

[0216] 101a Reverse Allocation Table

[0217] 102 Shift amount determination unit

[0218] 102a Shift amount allocation table

[0219] 103 Shift amount / reversal information storage unit

[0220] 104 Output selection unit

[0221] 110 Shift register

[0222] 111 Code sequence storage unit

[0223] 112 Detection pattern detection unit

[0224] 113 Division pattern detection unit

[0225] 114 Bit string detection unit

[0226] 115 Command Recovery Department

[0227] 120 Shift register

[0228] 121 Manchester Coding Department

[0229] 122 Detection pattern detection unit

[0230] 123 Division pattern detection unit

[0231] 124 Bit string detection unit

[0232] c1 Detection pattern

[0233] c2 control information

[0234] CN1, CN2 chip sequence

[0235] DS Downlink Signal

[0236] DS_pos Position signal

[0237] DS_res data signal

[0238] EN start signal

[0239] II Reversal Information

[0240] II1 First reversal information

[0241] II2 Second reversal information

[0242] IIIB Inversion information indication bit

[0243] NR fixed encoding

[0244] NRa Fixed Chip

[0245] PN extension code

[0246] PNa code column

[0247] SA Shift

[0248] SA1 First shift amount

[0249] SA2 Second shift amount

[0250] SAIB shift amount indication bit string

[0251] STP partition pattern

[0252] SW switch

[0253] US uplink signal

[0254] US_c1 First control signal

[0255] US_c2 Second control signal

Claims

1. A method for communicating between a sensor controller used in a position detector and a position indicator, wherein the sensor controller has a transmitting unit and a control unit, the transmitting unit is a circuit for transmitting a first control signal and a second control signal, and includes a first control signal supply unit, a switch, an expansion processing unit, and a code sequence holding unit, the switch selects either the first control signal supply unit or the control unit, and supplies the output of the selected one to the expansion processing unit, wherein: The method comprises the following steps: When the switch selects the control unit, control information is supplied to the extension processing unit, the control information being information including an instruction indicating content of instruction to the position indicator, generated by the control unit, and transmitted through the second control signal, the second control signal being transmitted with a division pattern as a preamble and subsequently including a transmission signal corresponding to a plurality of the control information, the preamble including a first chip sequence generated based on a predetermined encoding; The spreading processing unit performs primary modulation on the predetermined code based on the value of the symbol supplied via the switch to obtain a second chip sequence; The position indicator detects the preamble; The position indicator can obtain the data constituting the control information without mistaking the determination of polarity reversal and non-reversal even when the signal from the position detector arrives via the housing instead of the electrode and the polarity of the signal obtained via the electrode is reversed; The position indicator controls transmission of a signal to the position detector according to the data.

2. The method according to claim 1, wherein: The prescribed code is an extended code having an autocorrelation characteristic.

3. The method according to claim 1 or 2, wherein: The division pattern is composed of a pattern consisting of two consecutive bit string non-corresponding values ​​corresponding to the specified code, or a pattern consisting of two consecutive bit string non-corresponding values ​​corresponding to the inversion code that inverts the polarity of the specified code, wherein the bit string non-corresponding value is a value that is not converted into a bit string, When the position indicator detects a pattern in which a bit string non-corresponding value corresponding to an inversion code that inverts the polarity of the predetermined code is consecutively displayed twice, the position indicator inverts all subsequent chip sequences after the detection.

4. The method according to claim 3, wherein: The position indicator knows a detection pattern before detecting the sensor controller, the detection pattern being a pattern of values ​​of a sign used by the position indicator to detect the presence of the sensor controller.

5. The method according to claim 4, wherein: The detection pattern is constituted by repetition of a bit string non-corresponding value corresponding to the predetermined code and a bit string non-corresponding value corresponding to an inverted code in which the polarity of the predetermined code is inverted.

6. A position indicator that transmits and receives signals relative to a position detector via capacitive coupling, wherein: Include: electrode; a receiving part, connected to the electrode during reception; a transmitting unit connected to the electrodes during transmission; and a control unit connected to the receiving unit and the sending unit, The receiving unit sequentially detects a division pattern as a preamble code and a transmission signal corresponding to a plurality of control information sent by a sensor controller used in the position detector, wherein the control information is information including instructions indicating content of instructions to the position indicator, and the preamble code includes a first chip sequence generated based on a prescribed encoding, Furthermore, even when the signal from the position detector arrives via the housing instead of the electrode and the polarity of the signal obtained via the electrode is reversed, the receiving unit will not misjudge the determination of polarity reversal or non-reversal, and can obtain the data constituting the control information and supply it to the control unit. The control unit controls transmission of the signal by the transmission unit based on the data.

7. The position indicator according to claim 6, wherein: The position indicator knows a detection pattern before detecting the sensor controller, the detection pattern being a pattern of values ​​of a sign used by the position indicator to detect the presence of the sensor controller, The detection pattern is constituted by repetition of a bit string non-corresponding value corresponding to the predetermined code and a bit string non-corresponding value corresponding to an inverted code in which the polarity of the predetermined code is inverted.

8. The position indicator according to claim 7, wherein: The control unit is activated when an activation signal is supplied from the receiving unit, and the receiving unit issues the activation signal to the control unit when the detection pattern is detected. 9 . A sensor controller that communicates with the position indicator using the method according to claim 1 .

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