Integrated Circuits

Abstract

To enable simultaneous use of both an electronic pen having an integrated circuit compatible with both old and new protocols and an electronic pen having an integrated circuit compatible only with the old protocol, in one electronic device.SOLUTION: An integrated circuit 27 is an integrated circuit for a pen configured to be capable of receiving both a first uplink signal generated according to a first protocol and a second uplink signal generated according to a second protocol different from the first protocol. After entering a second operating mode according to the second protocol in response to receiving the second uplink signal, the integrated circuit transmits a second downlink signal according to the second protocol when the first uplink signal is received.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a pen and sensor controller. [Background technology]

[0002] 2. Description of the Related Art In recent years, there has been an increase in the use of electronic devices having large touch surfaces, such as electronic whiteboards, in which multiple electronic pens are used to simultaneously operate (draw on) the surface.

[0003] Patent Document 1 discloses an example of a sensor controller that enables simultaneous drawing with two electronic pens. The sensor controller in this example assigns a different local ID to each of the two detected electronic pens, and includes this local ID in a command signal, thereby enabling the electronic pens to be controlled individually.

[0004] Patent Document 2 discloses an example of a sensor controller that establishes synchronization with an electronic pen when it detects a pulse train of a predetermined length transmitted by the electronic pen. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 043203 [Patent Document 2] U.S. Patent Publication No. 2015 / 0256329 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the protocol for signals transmitted and received bidirectionally between the electronic pen and the sensor controller may change due to technological advances, etc. As a result, a situation may arise in which some of two or more electronic pens used simultaneously in an electronic device support a new protocol (hereinafter referred to as the "new protocol"), while others support only the old protocol (hereinafter referred to as the "old protocol"). Therefore, there has been a need for a single electronic device that can use both an electronic pen that supports both the new and old protocols (hereinafter referred to as the "new pen") and an electronic pen that supports only the old protocol (hereinafter referred to as the "old pen").

[0007] Therefore, one object of the present invention is to provide an electronic pen and a sensor controller that allows both a new pen and an old pen to be used simultaneously in one electronic device. [Means for solving the problem]

[0008] A pen according to one aspect of the present invention is a pen configured to receive an uplink signal generated in accordance with a first protocol, and to transmit a downlink signal based on the timing of reception of the uplink signal and the command placed in the uplink signal, and if, after receiving the uplink signal, during a period in which it is possible to receive the next uplink signal, it receives an uplink signal in a special state without successfully receiving the next uplink signal, it transmits the downlink signal in accordance with the first protocol, including data in accordance with the command placed in the first uplink signal received before that period, or including default data.

[0009] Another aspect of the present invention provides a pen configured to receive both a first uplink signal generated according to a first protocol and a second uplink signal generated according to a second protocol different from the first protocol, and which enters a second operating mode according to the second protocol in response to receiving the second uplink signal, and then transmits a second downlink signal according to the second protocol when it receives the first uplink signal.

[0010] A sensor controller according to the present invention is a sensor controller configured to be able to detect both a first downlink signal generated in accordance with a first protocol and a second downlink signal generated in accordance with a second protocol different from the first protocol, and is configured to alternately set first frames for transmitting a first uplink signal for the first protocol and second frames for transmitting a second uplink signal for the second protocol at a set ratio, and detects both the first and second downlink signals within the second frames. [Effects of the Invention]

[0011] According to the present invention, it becomes possible to use both the new pen and the old pen at the same time in one electronic device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an overall view of a position detection system 1 according to an embodiment of the present invention. [Figure 2] 10 is a diagram showing a transmission (Tx) and reception (Rx) schedule in the sensor controller 31. FIG. [Figure 3] FIG. 10 is a diagram showing the configuration of a downlink signal DS. [Figure 4] FIG. 1 is a diagram showing the configuration of an uplink signal US. [Figure 5] FIG. 2 is a diagram showing the internal configuration of the pen 2. [Figure 6] FIG. 2 is a diagram showing the internal configuration of the electronic device 3. [Figure 7] FIG. 1(a) is a diagram showing an example of the configuration of an uplink signal US1, and (b) to (g) are diagrams showing example configurations of an uplink signal US2, respectively. [Figure 8] 10A shows an example of a spreading code that constitutes a preamble PRE used in the old protocol, and FIG. 10B shows an example of a spreading code that constitutes a preamble PRE that is used in the new protocol. [Figure 9] FIG. 10 is a mode transition diagram of the old pen, pen 2a. [Figure 10] This is a mode transition diagram for the new pen, pen 2b. [Figure 11] FIG. 2 is a mode transition diagram of the sensor controller 31. [Figure 12] 10 is a diagram illustrating mode transitions of the sensor controller 31. FIG. [Figure 13] 10 is a diagram illustrating mode transitions of the sensor controller 31. FIG. [Figure 14] 10 is an explanatory diagram illustrating a procedure for transitioning communication with a pen 2b paired with an old protocol to a new protocol. FIG. [Figure 15] FIG. 10 is a mode transition diagram of a pen 2b according to a first modified example of the embodiment of the present invention. [Figure 16] FIG. 10 is a diagram showing a schedule of transmission (Tx) and reception (Rx) in a sensor controller 31 according to a second modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] 1 is a diagram showing the entirety of a position detection system 1 according to this embodiment. As shown in the figure, the position detection system 1 includes two pens 2a and 2b and an electronic device 3. The electronic device 3 includes a sensor electrode 30, a sensor controller 31, a panel 32, an electronic device control unit 33, and a liquid crystal display unit 34.

[0015] Both pens 2a and 2b are active styluses that support the active electrostatic method and can be used simultaneously or separately by one or more users. Hereinafter, when there is no need to particularly distinguish between pens 2a and 2b, they may be collectively referred to as pen 2.

[0016] The pen 2 and the sensor controller 31 are configured to be able to communicate bidirectionally. Hereinafter, as also shown in Fig. 1, a signal transmitted from the sensor controller 31 to the pen 2 will be referred to as an uplink signal US, and a signal transmitted from the pen 2 to the sensor controller 31 will be referred to as a downlink signal DS.

[0017] The uplink signal US and the downlink signal DS are transmitted and received according to a predetermined protocol, but this protocol may change due to technological advances, etc. In the following, a protocol that is newly released at a certain point in time will be referred to as a new protocol (second protocol), and the protocol that was previously used will be referred to as an old protocol (first protocol). The following explanation will be given assuming that pen 2a is an electronic pen (old pen) that supports only the old protocol, and pen 2b is an electronic pen (new pen) that supports both the old and new protocols.

[0018] To give an overview of input operations using the pen 2, the user gradually brings the pen 2 closer to the surface (touch surface) of the panel 32 (pen down, indicated as "DOWN" in Figure 1), and finally brings the tip of the pen 2 into contact with the touch surface (pen touch). Then, when the user moves the pen tip on the touch surface while maintaining this contact state (pen move), a trajectory of the movement is drawn on the touch surface by processing in the electronic device 3. Figure 1 shows three trajectories st1 to st3 as examples of trajectories drawn in this way. The drawing of the trajectories continues until the user removes the tip of the pen 2a from the touch surface (pen up, indicated as "UP" in Figure 1).

[0019] The pen 2 is configured to detect an uplink signal US supplied by the sensor controller 31 via the sensor electrode 30, and to transmit a predetermined downlink signal DS in response to the uplink signal US. As will be described in detail below, the sensor controller 31 receives this downlink signal DS via the sensor electrode 30, thereby obtaining the position of the pen 2 on the touch surface and the data transmitted by the pen 2. The position and data obtained by the sensor controller 31 are sequentially supplied to the electronic device control unit 33. The electronic device control unit 33 generates stroke data based on the supplied position and data, renders it, and outputs it to the liquid crystal display unit 34, thereby drawing the above-mentioned trajectory on the touch surface.

[0020] 2 is a diagram showing a transmission (Tx) and reception (Rx) schedule in the sensor controller 31. As shown in the diagram, the sensor controller 31 is configured to transmit an uplink signal US and receive a downlink signal DS in units of frames F. Within each frame F, the transmission of the uplink signal US and the reception of the downlink signal DS are performed in a time-division manner. Specifically, first, at the beginning of each frame F, the sensor controller 31 transmits an uplink signal US. Then, for the remaining time of each frame F, the pen 2 transmits a downlink signal DS.

[0021] As can be seen from FIG. 2, in this embodiment, two receiving time slots TS1 and TS2 are provided in one frame F. Hereinafter, when there is no need to particularly distinguish between the time slots TS1 and TS2, they may be collectively referred to as time slot TS. These time slots TS are provided so that different pens 2 can transmit downlink signals DS in a time-division manner. In this embodiment, by providing two time slots TS1 and TS2, a maximum of two pens 2 can transmit downlink signals DS within one frame F. This means that a maximum of two pens 2 can be simultaneously paired with a sensor controller 31. However, as illustrated in FIG. 16 (described later), the number of pens 2 that can simultaneously pair with a sensor controller 31 is not limited to two. The time slot TS used by each pen 2 is determined when the sensor controller 31 and the pen 2 are paired.

[0022] 3A and 3B are diagrams showing the configuration of a downlink signal DS, in which (a) shows a downlink signal DS transmitted by a pen 2 that has not yet detected the sensor controller 31, and (b) shows a downlink signal DS transmitted by a pen 2 that is paired with the sensor controller 31.

[0023] As shown in FIG. 3(a), the pen 2 that has not yet detected the sensor controller 31 transmits only a position signal PS as a downlink signal DS. The position signal PS is, for example, an unmodulated carrier signal. In this case, the position signal PS is used by the sensor controller 31 to detect the position of the pen 2 across the entire touch surface. This position detection is referred to as "global scan" in this specification. A specific method for position detection using global scan will be described later.

[0024] On the other hand, as shown in Fig. 3(b), the pen 2 paired with the sensor controller 31 transmits the data signal DATA as a downlink signal DS in addition to the position signal PS described above. In this case, the position signal PS is used by the sensor controller 31 to update the position of the pen 2. This position update is referred to as "local scan" in this specification. A specific method for updating the position by local scan will also be described later.

[0025] The data signal DATA is a signal for transmitting data held in the pen 2 to the sensor controller 31, and is configured to include a writing pressure value detected by a writing pressure detection unit 23 (see FIG. 5) described later, a value indicating the on / off state of a switch provided on the side or bottom of the housing of the pen 2, and a pen ID for uniquely identifying each pen 2. The pen 2 normally transmits a downlink signal DS in which only the writing pressure value is placed in the data signal DATA. On the other hand, when the sensor controller 31 instructs the pen 2 to transmit specific data by a command COMDATA described later, the pen 2 transmits a downlink signal DS including data according to the command COMDATA.

[0026] 3(b) is flag information that has a different value depending on whether the pen 2 supports only the old protocol or both the old and new protocols, and is used to notify the sensor controller 31 of its support status for the new protocol. Bit A only needs to be included in the downlink signal DS generated in accordance with the old protocol, and does not have to be included in the downlink signal DS generated in accordance with the new protocol.

[0027] 4 is a diagram showing the configuration of the uplink signal US. As shown in the figure, the uplink signal US includes a preamble PRE, a command signal COM, and an error detection code CRC.

[0028] The preamble PRE is a synchronization signal known to the pen 2 for synchronizing the pen 2 with the sensor controller 31. This synchronization signal is composed of a predetermined spread code (pulse train) made up of chips with a predetermined chip width (e.g., 0.5 us, 1.0 us, 2.0 us, etc.). The chip length (code length of the spread code) of this spread code is, for example, 7, 15, 31, 63 [chips], etc. Two or more spread codes with such chip lengths may be concatenated to form the synchronization signal. As another example, the synchronization signal may be a pulse train of a specific frequency in which a predetermined number of pulses, each having a pulse width as in the above example, are consecutive. The pen 2 continuously or intermittently detects the spread code that makes up the preamble PRE, and when it detects the preamble PRE, it detects the presence of the sensor controller 31 and synchronizes with the sensor controller 31 based on the timing of detecting the preamble PRE. The synchronization here means determining the transmission timing of the downlink signal DS and the reception timing of the next uplink signal US (i.e., the transmission and reception schedule of the uplink signal US and the downlink signal DS) based on the timing of detecting the preamble PRE. The pen 2 is configured to update this synchronization every time it receives an uplink signal US.

[0029] The command signal COM is composed of a local ID (LID) indicating the pen 2 that is the destination of this command signal COM, a command COMDATA containing instructions for the pen 2, and slot status information STA that represents the availability of each of the time slots TS1 and TS2 shown in Figure 2 with one bit each.

[0030] The error detection code CRC is a code obtained by performing a predetermined calculation using the command signal COM as an input, and is used to detect errors that occur during transmission of the command signal COM.

[0031] When the pen 2 receives the uplink signal US without having yet discovered the sensor controller 31, it checks the availability of time slots TS1 and TS2 by referring to the slot status information STA. If either of the time slots TS is found to be available, it uses that time slot TS to transmit a downlink signal DS containing only the position signal PS. The sensor controller 31, having received this downlink signal DS, changes the slot status information STA of the time slot TS in which the downlink signal DS was received to "in use" in the next uplink signal US it transmits. By detecting the change in the slot status information STA, the pen 2, having received this uplink signal US, detects that it has been detected by the sensor controller 31, and acquires a predetermined local ID (e.g., 0 for time slot TS1, 1 for time slot TS2, etc.) corresponding to the time slot TS from which it transmitted the downlink signal DS, and stores it in its own memory.

[0032] When the pen 2 subsequently receives and decodes an uplink signal US, it first references the local ID in the command signal COM and determines whether it matches the local ID stored in its own memory 45, thereby determining whether the uplink signal US was intended for itself. If this determination determines that the uplink signal US was intended for itself, the pen 2 extracts the command COMDATA from the command signal COM and performs processing according to its contents. This processing includes obtaining data requested for transmission by the sensor controller 31 and placing it in the next or subsequent downlink signal DS. On the other hand, if it determines that the uplink signal US was not intended for itself, the pen 2 transmits a default downlink signal DS including a position signal PS and a data signal DATA containing only a writing pressure value, without obtaining the command COMDATA in the command signal COM.

[0033] The sensor controller 31 is configured to detect the presence and position of the pen 2 by receiving a position signal PS using the sensor electrodes 30. The pointed positions P1 and P2 shown in FIG. 1 are examples of positions detected in this way. The above-mentioned trajectories st1 to st3 are the trajectories of movement of the pointed positions P1 and P2. The sensor controller 31 is also configured to acquire data (such as writing pressure values) transmitted by the pen 2 by receiving a data signal DATA using the sensor electrodes 30.

[0034] 5 is a diagram showing the internal configuration of the pen 2. As shown in the figure, the pen 2 is configured to include a core body 20, a pen tip electrode 22, a writing pressure detection unit 23, a power source 26, and an integrated circuit 27.

[0035] Core body 20 is a rod-shaped member arranged so that its longitudinal direction coincides with the pen axis direction of pen 2, and one end thereof forms pen tip portion 21 of pen 2. A conductive material is applied to the surface of core body 20, forming pen tip electrode 22.

[0036] The pen tip electrode 22 is a conductor provided near the core body 20 and is electrically connected to the integrated circuit 27 by wiring. The integrated circuit 27 receives the uplink signal US and transmits the downlink signal DS via this pen tip electrode 22. However, the pen tip electrode 22 may be separated into a transmitting electrode and a receiving electrode.

[0037] The writing pressure detection unit 23 is a functional unit that detects the force (writing pressure value) applied to the pen tip portion 21. Specifically, the writing pressure detection unit 23 abuts against the rear end of the core body 20, and is configured to detect, through this abutment, the force applied to the pen tip portion 21 when the user presses the pen tip of the pen 2 against a touch surface or the like. In a typical example, the writing pressure detection unit 23 is configured by a variable capacitance module whose capacitance changes in response to the force applied to the pen tip portion 21.

[0038] The power supply 26 is for supplying operating power (DC voltage) to the integrated circuit 27, and is formed of, for example, a cylindrical AAAA battery.

[0039] The integrated circuit 27 is a processing unit configured by a group of circuits formed on a substrate (not shown), and performs the following processes: receiving an uplink signal US via the pen tip electrode 22; generating a downlink signal DS based on the received uplink signal US; and transmitting the generated downlink signal DS via the pen tip electrode 22. The type of protocol supported by the pen 2 (only the old protocol, or both the new and old protocols) is determined by at least one of the firmware and hardware of the integrated circuit 27.

[0040] 9, the integrated circuit 27 of the pen 2a, which is an old pen that supports only the old protocol, is configured to operate in any one of a discovery mode S0 for discovering the sensor controller 31, a communication mode S1 for communicating with the discovered sensor controller 31, and a continuation mode S1a for continuing communication with the sensor controller 31 even when an uplink signal US in a special state, which will be described later, is received after entering the communication mode S1. Hereinafter, an uplink signal US in a special state will be referred to as an "uplink signal SUS," and an uplink signal US that is normally received according to the old protocol will be referred to as an "uplink signal NUS."

[0041] 10, the integrated circuit 27 of the pen 2b, which is a new pen compatible with both the old and new protocols, is configured to operate in any one of the following modes: a discovery mode S10 for discovering the sensor controller 31; an old mode S11 (first operating mode) for communicating with the discovered sensor controller 31 using the old protocol; an old continuation mode S11a for continuing communication with the sensor controller 31 even when an uplink signal US generated according to the new protocol is received after entering the old mode S11; a new mode S12 (second operating mode) for communicating with the discovered sensor controller 31 using the new protocol; and a new continuation mode S12a for continuing communication with the sensor controller 31 even when an uplink signal US generated according to the old protocol is received after entering the new mode S12. Hereinafter, the uplink signal US generated according to the old protocol will be referred to as an “uplink signal US1,” and the uplink signal US generated according to the new protocol will be referred to as an “uplink signal US2.” For pen 2a, uplink signal US1 is uplink signal NUS, and uplink signal US2 is uplink signal SUS.

[0042] 6 is a diagram showing the internal configuration of the electronic device 3. Hereinafter, the configuration and operation of the electronic device 3 will be described in detail with reference to this FIG.

[0043] The sensor electrode 30 is composed of a plurality of linear electrodes 30X each extending in the Y direction and a plurality of linear electrodes 30Y each extending in the X direction. The sensor electrode 30 is configured to be capacitively coupled with the pen 2 by these linear electrodes 30X and 30Y. The above-mentioned uplink signal US and downlink signal DS are transmitted and received via this capacitive coupling.

[0044] As shown in FIG. 6, the sensor controller 31 includes an MCU 60, a logic unit 61, a transmitting unit 62, a receiving unit 63, and a selecting unit 64.

[0045] The MCU 60 and logic unit 61 are control units that control the transmission and reception operations of the sensor controller 31 by controlling the transmission unit 62, the reception unit 63, and the selection unit 64. Specifically, the MCU 60 is a microprocessor that has an internal ROM and RAM and operates based on a predetermined program. In addition to controlling the logic unit 61, the processes performed by the MCU 60 include generating a command signal COM and an error detection code CRC under the control of the electronic device control unit 33 and supplying them to the transmission unit 62, and deriving the coordinates x, y of the pen 2 based on the downlink signal DS supplied from the reception unit 63, receiving data Res transmitted by the pen 2, and outputting them together with the local ID of the pen 2 to the electronic device control unit 33. Meanwhile, the logic unit 61 is configured to output control signals ctrl_t1 to ctrl_t4 and ctrl_r under the control of the MCU 60.

[0046] The MCU 60 is configured to transmit an uplink signal US and receive a downlink signal DS according to the transmission / reception schedule shown in FIG. 2. As will be described in detail later with reference to FIG. 11, the MCU 60 has three transmission modes for the uplink signal US: a new / old mixed mode, an old-only mode, and a new-only mode. When the MCU 60 is in the new / old mixed mode, the MCU 60 is configured to alternately set a frame F (first frame) for transmitting an uplink signal US1 for the old protocol and a frame F (second frame) for transmitting an uplink signal US2 for the new protocol at a set ratio (e.g., 1:1). On the other hand, when the MCU 60 is in the old-only mode, the MCU 60 is configured to transmit an uplink signal US1 for the old protocol in every frame F. When the MCU 60 is in the new-only mode, the MCU 60 is configured to transmit an uplink signal US2 for the new protocol in every frame F.

[0047] Also, as will be described in detail later with reference to FIG. 11 , the MCU 60 has three reception modes for the downlink signal DS for each time slot TS: discovery mode, old mode, and new mode. In a time slot TS that has entered the discovery mode, the MCU 60 waits to receive a downlink signal DS transmitted by an unpaired pen 2. In a time slot TS that has entered the old mode, the MCU 60 waits to receive a downlink signal DS generated by the pen 2 in accordance with the old protocol. On the other hand, in a time slot TS that has entered the new mode, the MCU 60 waits to receive a downlink signal DS generated by the pen 2 in accordance with the new protocol. Hereinafter, the downlink signal DS generated in accordance with the old protocol will be referred to as a "downlink signal DS1," and the downlink signal DS generated in accordance with the new protocol will be referred to as a "downlink signal DS2."

[0048] Here, the reception mode of the downlink signal DS is set regardless of the transmission mode of the uplink signal US. Therefore, the MCU 60 may detect both the downlink signals DS1 and DS2 in a frame F in which the uplink signal US1 is transmitted, and may also detect both the downlink signals DS1 and DS2 in a frame F in which the uplink signal US2 is transmitted.

[0049] FIG. 7(a) is a diagram showing an example of the configuration of uplink signal US1, and FIGS. 7(b) to 7(g) are diagrams showing examples of the configuration of uplink signal US2. Both uplink signals US1 and US2 have the configuration shown in FIG. 4 and share some common parts, but there are differences due to differences in protocol. The content of these differences is not particularly limited, and various variations are possible. FIGS. 7(b) to 7(g) show six of such variations. Each will be described in detail below.

[0050] FIG. 7(b) shows an example in which the value of bit B, which is specified as a first value (e.g., "0") in the old protocol, is set to a second value (e.g., "1") different from the first value in the new protocol. In this case, the new pen 2b can determine whether the uplink signal US is an uplink signal US1 or US2 by referring to the value of bit B after decoding the received uplink signal US. On the other hand, the old pen 2a determines that the received uplink signal US was received normally if bit B has the first value, but determines that an abnormality was detected in the decoding of the command if bit B has the second value. In the former case, the received uplink signal US is determined to be the uplink signal NUS described above, and in the latter case, the received uplink signal US is determined to be an uplink signal SUS in the special state described above.

[0051] The uplink signal US2 in FIG. 7(b) can be used, for example, when the uplink signal US1 contains a reserved field. The value of the reserved field does not have a specific meaning, but usually has a specific value (e.g., "0"). When designing the old protocol, it is impossible to specifically predict how bits will be assigned to this field in the new protocol. However, by setting a value (e.g., "1") different from the specific value in the field when designing the new protocol, the pen 2a can recognize that an unusual value is set in the field when receiving the uplink signal US1. Therefore, it becomes possible to determine that the received uplink signal US is an uplink signal SUS in a special state.

[0052] 7(c) shows an example in which, in the new protocol, instead of the error detection code CRC obtained by performing a predetermined calculation using the command signal COM as input, an inverted error detection code RCRC obtained by inverting the error detection code CRC is placed in the uplink signal US. In this case, the new pen 2b extracts a portion corresponding to the error detection code CRC or the inverted error detection code RCRC from the received uplink signal US, and attempts error detection without inverting that portion and also attempts error detection with inverting that portion, thereby determining whether the uplink signal US is the uplink signal US1 or US2. In other words, the pen 2b can determine that it has received the uplink signal US2 if no error is detected after inverting the extracted portion and, on the other hand, can determine that it has received the uplink signal US1 if no error is detected after performing error detection without inverting the extracted portion. On the other hand, in the old pen, pen 2a, if the error detection code CRC is placed in the received uplink signal US, the decoded result will be a code word (i.e., errors will not be detected by the error detection code), but if the inverted error detection code RCRC is placed, the decoded result will not be a code word (i.e., errors will be detected by the error detection code). Therefore, if the decoded result is a code word, or if it is not a code word and the CRC field contains an inverted value, pen 2a determines that the received uplink signal US is the uplink signal NUS described above. If the decoded result is not a code word, pen 2a determines that the received uplink signal US is the uplink signal SUS in the special state described above. In this way, it is possible to indicate that a command conforming to the new protocol has been issued by using the CRC field existing in the old protocol without using a new field as shown in Figure 7(b).

[0053] 7(d) shows an example in which the preamble PRE of the new protocol is longer than the preamble PRE of the old protocol. FIG. 7(e) shows an example in which the new protocol, unlike the old protocol, does not include an error detection code CRC. FIG. 7(f) shows an example in which the time length of the command signal COM of the new protocol is shorter than that of the command signal COM of the old protocol due to multi-level coding or the like. FIG. 7(g) shows an example in which the new protocol, unlike the old protocol, does not include an error detection code CRC and the time length of the command signal COM of the new protocol is shorter than that of the command signal COM of the old protocol due to multi-level coding or the like. In either case, the new pen 2b attempts to decode the received uplink signal US assuming that it is the uplink signal US1 or US2, thereby determining whether the uplink signal US is the uplink signal US1 or US2. On the other hand, the old pen 2a decodes the uplink signal US only as the uplink signal US1, and therefore will obtain an abnormal result if the uplink signal US is the uplink signal US2. Therefore, if a normal decoding result is obtained, the pen 2a determines that the received uplink signal US is the above-mentioned uplink signal NUS, and if an abnormal decoding result is obtained, it determines that the received uplink signal US is the above-mentioned special state uplink signal SUS.

[0054] In addition, when different preambles PRE are used between the old protocol and the new protocol as in the example shown in Figure 7(d), the preambles PRE may be configured so that only a portion of the preambles PRE match, such as the chip width of the spreading code (the time length per chip, i.e., the fundamental frequency or an integer multiple frequency of the chip (pulse)), a partial match (including a match such that the correlation calculation result is equal to or greater than a predetermined value) of the code (chip sequence) constituting the spreading code, or the beginning portion of the preamble PRE composed of multiple spreading code patterns. In this case, if the old pen 2a detects this partial match in addition to obtaining an abnormal decoding result, it may determine that the received uplink signal US is an uplink signal SUS in the above-mentioned special state. This makes it possible to prevent the reception of an uplink signal SUS in the special state from being determined to be received even in cases such as a decoding error due to noise.

[0055] 8(a) shows an example of a spreading code constituting the preamble PRE used in the old protocol, and FIG. 8(b) shows an example of a spreading code constituting the preamble PRE used in the new protocol. In these examples, different preambles PRE are used in the old protocol and the new protocol, but the chip width L of the spreading codes is the same. When using a preamble PRE like this example, the old pen 2a can determine that the received uplink signal US is the uplink signal SUS in the special state described above when it detects a match in the chip width L in addition to obtaining an abnormal decoding result (including a result in which the entire preamble PRE (or uplink signal US) does not match). The same applies when it detects a partial match in the codes constituting the spreading codes or the preamble PRE instead of or in addition to a match in the chip width L.

[0056] Returning to Fig. 6, the transmitting unit 62 is a circuit that generates an uplink signal US under the control of the MCU 60 and the logic unit 61, and is configured to include a pattern supplying unit 80, a switch 81, a code string holding unit 82, a spreading processing unit 83, and a transmission guard unit 84, as shown in Fig. 6. Of these, the pattern supplying unit 80 in particular will be described as being included in the transmitting unit 62 in this embodiment, but it may also be included in the MCU 60.

[0057] The pattern supplying unit 80 is a functional unit that outputs symbols that make up the preamble PRE in accordance with instructions from a control signal ctrl_t1 supplied from the logic unit 61. The symbols that make up the preamble PRE are made up of symbols that are exclusive to the preamble and do not correspond to any of 0 to 15, for example.

[0058] The switch 81 serves to select either the pattern supplying unit 80 or the MCU 60 based on a control signal ctrl_t2 supplied from the logic unit 61, and to supply the output of the selected one to the spreading processing unit 83. When the switch 81 selects the pattern supplying unit 80, the spreading processing unit 83 is supplied with symbols constituting the preamble PRE from the pattern supplying unit 80. On the other hand, when the switch 81 selects the MCU 60, the spreading processing unit 83 is supplied with a command signal COM and an error detection code CRC from the MCU 60. The command signal COM and the error detection code CRC supplied to the spreading processing unit 83 are each made up of a sequence of symbols associated with any of the numbers 0 to 15, for example.

[0059] The code sequence holding unit 82 has a function of generating and holding a spreading code PN of a predetermined chip length having autocorrelation characteristics, based on a control signal ctrl_t3 supplied from the logic unit 61. A different spreading code PN is held in the code sequence holding unit 82 for each type of symbol. The spreading code PN held in the code sequence holding unit 82 is supplied to a spreading processing unit 83.

[0060] The spreading processing unit 83 has a function of obtaining a transmission chip sequence by spreading the symbol value (preamble PRE or command signal COM) supplied via the switch 81 with a corresponding one of a plurality of spreading codes PN held in the code sequence holding unit 82. The spreading processing unit 83 is configured to supply the obtained transmission chip sequence to a transmission guard unit 84.

[0061] The transmission guard unit 84 has the function of inserting a guard period (a period in which neither transmission nor reception is performed) required to switch between transmission and reception operations between the transmission period of the uplink signal US and the reception period of the downlink signal DS based on the control signal ctrl_t4 supplied from the logic unit 61.

[0062] The receiving unit 63 is a circuit for receiving the downlink signal DS transmitted by the pen 2 based on the control signal ctrl_r supplied from the logic unit 61. Specifically, it is configured to include an amplifier circuit 85, a detection circuit 86, and an analog-to-digital (AD) converter 87.

[0063] The amplifier circuit 85 amplifies and outputs the downlink signal DS supplied from the selector 64. The detector circuit 86 is a circuit that generates a voltage corresponding to the level of the output signal of the amplifier circuit 85. The AD converter 87 is a circuit that generates a digital signal by sampling the voltage output from the detector circuit 86 at predetermined time intervals. The digital signal output by the AD converter 87 is supplied to the MCU 60. Based on the digital signal thus supplied, the MCU 60 acquires the data Res (pen pressure value, pen ID, etc.) transmitted by the pen 2.

[0064] The selection unit 64 includes switches 88x and 88y and conductor selection circuits 89x and 89y.

[0065] Each of the switches 88x and 88y is a one-circuit, two-contact switch element configured so that a common terminal is connected to either a T terminal or an R terminal. The common terminal of the switch 88x is connected to a conductor selection circuit 89x, the T terminal is connected to an output terminal of the transmitter 62, and the R terminal is connected to an input terminal of the receiver 63. The common terminal of the switch 88y is connected to a conductor selection circuit 89y, the T terminal is connected to an output terminal of the transmitter 62, and the R terminal is connected to an input terminal of the receiver 63.

[0066] The conductor selection circuit 89x is a switch element for selectively connecting the plurality of linear electrodes 30X to a common terminal of the switch 88x. The conductor selection circuit 89x is configured to be able to simultaneously connect some or all of the plurality of linear electrodes 30X to the common terminal of the switch 88x.

[0067] The conductor selection circuit 89y is a switch element for selectively connecting the plurality of linear electrodes 30Y to a common terminal of the switch 88y. The conductor selection circuit 89y is also configured to be able to simultaneously connect some or all of the plurality of linear electrodes 30Y to the common terminal of the switch 88y.

[0068] The selector 64 is supplied with four control signals sTRx, sTRy, selX, and selY from the logic unit 61. Specifically, the control signal sTRx is supplied to the switch 88x, the control signal sTRy is supplied to the switch 88y, the control signal selX is supplied to the conductor selection circuit 89x, and the control signal selY is supplied to the conductor selection circuit 89y. The logic unit 61 controls the selector 64 using these control signals sTRx, sTRy, selX, and selY, thereby realizing the transmission of the uplink signal US and the reception of the downlink signal DS.

[0069] More specifically, when transmitting an uplink signal US, the logic unit 61 controls the selection unit 64 so that all of the multiple linear electrodes 30Y (or all of the multiple linear electrodes 30X) are connected to the output terminal of the transmission unit 62.

[0070] The operation of the logic unit 61 when receiving the position signal PS included in the downlink signal DS differs depending on whether or not pairing with the pen 2 is occurring during the time slot TS in which the position signal PS is received. During a time slot TS in which pairing is not occurring, the logic unit 61 controls the selection unit 64 so that all of the plurality of linear electrodes 30X, 30Y are sequentially connected to the input terminal of the receiving unit 63 within the duration of the time slot TS. This allows the MCU 60 to acquire the reception strength of the position signal PS from each of the linear electrodes 30X, 30Y, thereby enabling detection of the position of the pen 2 over the entire touch surface (global scan). On the other hand, during a time slot TS in which pairing is not occurring, the logic unit 61 controls the selection unit 64 so that a predetermined number of linear electrodes 30X, 30Y located near the previously detected position are sequentially connected to the input terminal of the receiving unit 63 while the transmission of the position signal PS continues. By doing this, the MCU 60 can acquire the reception strength of the position signal PS from each of a predetermined number of linear electrodes 30X, 30Y located in the vicinity of the previously detected position, thereby making it possible to update the position of the pen 2 (local scan).

[0071] When receiving the data signal DATA contained in the downlink signal DS, the logic unit 61 controls the selection unit 64 so that, of each of the plurality of linear electrodes 30X, 30Y, only one that is closest to the position of the pen 2 transmitting the data signal DATA, as derived from the immediately preceding position signal PS, is connected to the input end of the receiving unit 63. This makes it possible to fully utilize the transmission time of the data signal DATA for sending data from the pen 2 to the sensor controller 31.

[0072] We have explained above the configurations of the pen 2 and electronic device 3 that make up the position detection system 1, as well as the uplink signal US and downlink signal DS. Next, we will explain in more detail the operations of the pen 2 and electronic device 3 with reference to their respective mode transition diagrams.

[0073] 9 is a mode transition diagram for the old pen 2a. As shown in the diagram, the pen 2a is configured to operate in one of a discovery mode S0, a communication mode S1, and a continuation mode S1a.

[0074] Discovery mode S0 is a mode for discovering the sensor controller 31. The pen 2a in discovery mode S0 intermittently or continuously performs detection operations for the uplink signal US. When an uplink signal NUS is received, the pen 2a determines a transmission / reception schedule for the uplink signal US and the downlink signal DS based on the reception timing, and transitions to communication mode S1. On the other hand, when an uplink signal SUS is received, the pen 2a remains in discovery mode S0 and attempts to receive the next uplink signal US.

[0075] The pen 2a that has entered the communication mode S1 remains in the communication mode S1 and communicates with the sensor controller 31 while the uplink signal NUS is being received in accordance with the transmission / reception schedule. Specifically, the transmission / reception schedule is updated in accordance with the reception timing of the received uplink signal NUS, and the downlink signal DS is transmitted in accordance with the updated transmission / reception schedule. The downlink signal DS transmitted in this manner is a signal that the pen 2a generates in accordance with the old protocol, and includes data that the pen 2a is instructed to transmit by the command COMDATA in the immediately preceding uplink signal NUS, or predetermined data such as a pen pressure value.

[0076] On the other hand, if the uplink signal US is not received according to the transmission / reception schedule, the pen 2a determines that it has moved away from the sensor controller 31 and returns to the discovery mode S0. Also, if the uplink signal SUS is received without successfully receiving the next uplink signal NUS according to the transmission / reception schedule (i.e., during the period when the next uplink signal NUS can be received), the pen 2a transitions to the continuation mode S1a.

[0077] When the pen 2a in the continuous mode S1a receives an uplink signal SUS, the pen 2a transmits a downlink signal DS according to the old protocol while updating the transmission / reception schedule according to the timing of receiving the uplink signal SUS. Specifically, the pen 2a transmits a downlink signal DS including data according to the command placed in the uplink signal NUS received before the above-mentioned period, or predetermined data such as a pen pressure value.

[0078] On the other hand, if the uplink signal NUS is received, the pen 2a returns to the communication mode S1, and if the uplink signal SUS is detected n or more times (n is any natural number equal to or greater than 2) consecutively (i.e., the uplink signal NUS is not detected), or if the uplink signal US is not received according to the transmission / reception schedule, the pen 2a returns to the discovery mode S0.

[0079] 10 is a mode transition diagram for the new pen, pen 2b. As shown in the figure, pen 2b is configured to operate in any one of discovery mode S10, old mode S11, old continuation mode S11a, new mode S12, and new continuation mode S12a.

[0080] Discovery mode S10 is a mode for discovering the sensor controller 31, similar to discovery mode S0 of the pen 2a shown in Fig. 9. The pen 2b that has entered discovery mode S10 intermittently or continuously executes detection operations for the uplink signal US. When an uplink signal US1 is received, the pen 2b determines a transmission / reception schedule for the uplink signal US and the downlink signal DS based on the timing of reception of the uplink signal US1 and transitions to old mode S11. On the other hand, when an uplink signal US2 is received, the pen 2b determines a transmission / reception schedule for the uplink signal US and the downlink signal DS based on the timing of reception of the uplink signal US2 and transitions to new mode S12.

[0081] The pen 2b, which has entered the old mode S11, remains in the old mode S11 and communicates with the sensor controller 31 while the uplink signal US1 is being received in accordance with the transmission / reception schedule. Specifically, the transmission / reception schedule is updated in accordance with the reception timing of the received uplink signal US (including the uplink signals US1 and US2), and the downlink signal DS is transmitted in accordance with the updated transmission / reception schedule. The downlink signal DS transmitted in this manner is a signal generated by the pen 2b in accordance with the old protocol, and includes data instructed to be transmitted by the command COMDATA in the immediately preceding uplink signal US1, or predetermined data such as a pen pressure value.

[0082] On the other hand, if the uplink signal US is not received according to the transmission / reception schedule, the pen 2b determines that it has moved away from the sensor controller 31 and returns to the discovery mode S10. If the uplink signal US2 is received according to the transmission / reception schedule, the pen 2b transitions to the old continuation mode S11a.

[0083] When the pen 2b in the old continuation mode S11a receives the uplink signal US2, the pen 2b transmits the downlink signal DS according to the old protocol while updating the transmission / reception schedule according to the timing of receiving the uplink signal US2. Specifically, the pen 2b transmits the downlink signal DS including data according to the command placed in the uplink signal US1 that has been received up to that point, or predetermined data such as a pen pressure value.

[0084] On the other hand, if the uplink signal US1 is received, the pen 2b returns to the previous mode S11. Also, if the uplink signal US2 is detected n or more times (n is any natural number equal to or greater than 2) consecutively (i.e., the uplink signal US1 is not detected), or if the uplink signal US is not received according to the transmission / reception schedule, the pen 2b returns to the discovery mode S10.

[0085] Here, if the command COMDATA placed in the received uplink signal US1 is a transition command instructing a mode transition, the pen 2b preferably transitions to the new mode S12 as indicated by the dashed line in Fig. 10. This makes it possible to forcibly switch the mode of the pen 2b to the new mode S12 in response to an instruction from the sensor controller 31.

[0086] Next, the pen 2b that has entered the new mode S12 remains in the new mode S12 and communicates with the sensor controller 31 while the uplink signal US2 is being received in accordance with the transmission / reception schedule. Specifically, the transmission / reception schedule is updated in accordance with the reception timing of the received uplink signal US (including the uplink signals US1 and US2), and the downlink signal DS is transmitted in accordance with the updated transmission / reception schedule. The downlink signal DS transmitted in this manner is a signal that the pen 2b generates in accordance with the new protocol, and includes data instructed to be transmitted by the command COMDATA in the immediately preceding uplink signal US2, or predetermined data such as a writing pressure value.

[0087] On the other hand, if the uplink signal US is not received according to the transmission / reception schedule, the pen 2b determines that it has moved away from the sensor controller 31 and returns to the discovery mode S10. If the uplink signal US1 is received according to the transmission / reception schedule, the pen 2b transitions to the new continuation mode S12a.

[0088] When the pen 2b in the new continuous mode S12a receives the uplink signal US1, the pen 2b transmits the downlink signal DS according to the new protocol while updating the transmission / reception schedule according to the reception timing of the uplink signal US1. Specifically, the pen 2b transmits the downlink signal DS including data according to the command placed in the uplink signal US2 that has been received up to that point, or predetermined data such as a pen pressure value.

[0089] On the other hand, if the uplink signal US2 is received, the pen 2b returns to the new mode S12. Also, if the uplink signal US1 is detected n or more times (n is any natural number equal to or greater than 2) consecutively (i.e., the uplink signal US2 is not detected), or if the uplink signal US is not received according to the transmission / reception schedule, the pen 2b returns to the discovery mode S10.

[0090] FIG. 11 is a mode transition diagram of the sensor controller 31. As shown in the diagram, the sensor controller 31 has a reception mode for the downlink signal DS for each time slot TS, and a transmission mode for the uplink signal US. The former includes a discovery mode, an old mode, and a new mode, while the latter includes a new and old mixed mode, an old only mode, and a new only mode. Also, FIGS. 12 and 13 are explanatory diagrams for explaining the mode transition of the sensor controller 31. Hereinafter, the mode transition of the sensor controller 31 will be explained with reference to FIGS. 11 to 13.

[0091] First, state S20 shown in Fig. 11 is an initial state in which the sensor controller 31 is not paired with any pen 2. In this state S20, the reception modes of the two time slots TS1 and TS2 are both discovery mode, and the transmission mode of the uplink signal US is mixed new and old mode. In this case, the sensor controller 31 alternates between frames F transmitting an uplink signal US1 for the old protocol and frames F transmitting an uplink signal US2 for the new protocol at a set ratio. This ratio is preferably 1:1, but does not have to be 1:1.

[0092] 12(a) shows a case where, when the sensor controller 31 is in state S20, a downlink signal DS2 is received in time slot TS1 within frame F in which an uplink signal US2 was transmitted. The pen 2 that transmits the first downlink signal DS2 in response to the uplink signal US2 is pen 2b, and at the time of transmitting the downlink signal DS2, the pen 2b has entered the new mode S12 shown in FIG. 10. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS2 using the new protocol, and sets the reception mode for the downlink signal DS in time slot TS1 to the new mode (state S21 in FIG. 11). As a result, communication using the new protocol is carried out in time slot TS1.

[0093] 12(b) shows a case where, when the sensor controller 31 is in state S21, a downlink signal DS2 is received in time slot TS2 within frame F in which an uplink signal US2 was transmitted. The pen 2 transmitting this downlink signal DS2 is also pen 2b (a different pen 2b from the pen 2b transmitting the downlink signal DS2 in time slot TS1; the same applies below), and at the time of transmitting the downlink signal DS, the pen 2 entered the new mode S12 shown in FIG. 10. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS2 using the new protocol, sets the reception mode of the downlink signal DS in time slot TS2 to the new mode, and sets the transmission mode of the uplink signal US to the new-only mode (state S23 in FIG. 11). As a result, communication is performed using the new protocol in both time slots TS1 and TS2, and only the uplink signal US2 is transmitted as the uplink signal US.

[0094] FIG. 12(c) shows a case where, when the sensor controller 31 is in state S21, a downlink signal DS1 is received in time slot TS2 within frame F in which the uplink signal US1 was transmitted. The pen 2 transmitting this downlink signal DS1 can be either pen 2a or pen 2b. If it is pen 2a, it has entered communication mode S1 shown in FIG. 9 at the time it transmitted the downlink signal DS1. On the other hand, if it is pen 2b, it has entered old mode S11 shown in FIG. 10 at the time it transmitted the downlink signal DS1. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS1 using the old protocol, and sets the reception mode for the downlink signal DS in time slot TS2 to the old mode (state S24 in FIG. 11). As a result, communication is performed using the new protocol in time slot TS1, and communication is performed using the old protocol in time slot TS2.

[0095] FIG. 13(a) shows a case where, when the sensor controller 31 is in state S20, a downlink signal DS1 is received in time slot TS1 within frame F in which the uplink signal US1 was transmitted. The pen 2 that transmits the first downlink signal DS1 in response to the uplink signal US1 can be either pen 2a or pen 2b. If it is pen 2a, it has entered communication mode S1 shown in FIG. 9 at the time it transmitted the downlink signal DS1. On the other hand, if it is pen 2b, it has entered old mode S11 shown in FIG. 10 at the time it transmitted the downlink signal DS1. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS1 using the old protocol, and sets the reception mode for the downlink signal DS in time slot TS1 to the old mode (state S22 in FIG. 11). As a result, communication using the old protocol is performed in time slot TS1.

[0096] 13(b) shows a case where, when the sensor controller 31 is in state S22, a downlink signal DS2 is received in time slot TS2 within frame F in which the uplink signal US2 was transmitted. The pen 2 transmitting this downlink signal DS2 is pen 2b, and at the time of transmitting the downlink signal DS2, the pen 2b has entered the new mode S12 shown in FIG. 10. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS2 using the new protocol, and sets the reception mode for the downlink signal DS in time slot TS2 to the new mode (state S25 in FIG. 11). As a result, communication is performed using the old protocol in time slot TS1, and communication is performed using the new protocol in time slot TS2.

[0097] FIG. 13(c) illustrates a case where, when the sensor controller 31 is in state S22, a downlink signal DS1 is received in time slot TS2 within frame F in which the uplink signal US1 was transmitted. The pen 2 transmitting this downlink signal DS1 can be either pen 2a or pen 2b. If it is pen 2a, it has entered communication mode S1 shown in FIG. 9 upon transmitting the downlink signal DS1. On the other hand, if it is pen 2b, it has entered old mode S11 shown in FIG. 10 upon transmitting the downlink signal DS1. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS1 using the old protocol, sets the reception mode of the downlink signal DS in time slot TS2 to the old mode, and sets the transmission mode of the uplink signal US to old-only mode (state S26 in FIG. 11). As a result, communication is performed using the old protocol in both time slots TS1 and TS2, and only the uplink signal US1 is transmitted as the uplink signal US.

[0098] According to the above operation, even if the pen 2 to be paired is a pen 2b that supports the new protocol, if the uplink signal US detected for the first time after the pen 2b approaches the touch surface is the uplink signal US1, communication will be initiated using the old protocol. Therefore, when communication using the old protocol is initiated, the sensor controller 31 determines whether the pen 2 supports the new protocol by referring to bit A (see FIG. 2) included in the downlink signal DS1. If it determines that the pen 2 supports the new protocol, it places a transition command in the uplink signal US1 to be transmitted next, instructing the transition to communication using the new protocol. This point will be explained in detail below with reference to FIG. 14.

[0099] Figure 14 is an explanatory diagram for explaining the procedure for transitioning communication with pen 2b paired under the old protocol to the new protocol. Figure 14(a) shows the procedure for transitioning communication with pen 2b detected in time slot TS1 in state S20 shown in Figure 11 to the new protocol, Figure 14(b) shows the procedure for transitioning communication with pen 2b detected in time slot TS2 in state S21 shown in Figure 11 to the new protocol, and Figure 14(c) shows the procedure for transitioning communication with pen 2b detected in time slot TS2 in state S22 shown in Figure 11 to the new protocol. Each of these procedures will be explained below in order.

[0100] 14(a) shows a case in which the pen 2b, which has entered the old mode S11 upon receiving the uplink signal US1 while the sensor controller 31 is in state S20, transmits a downlink signal DS1 using time slot TS1. Upon receiving this downlink signal DS1, the sensor controller 31 pairs with the pen 2b in time slot TS1 using the old protocol and transitions to state S22.

[0101] Thereafter, the sensor controller 31 detects that the paired pen 2b supports both the old and new protocols from bit A (see FIG. 3(b)) included in the downlink signal DS1 transmitted by the paired pen 2b in time slot TS1. Note that bit A is included in the data signal DATA shown in FIG. 3(b), so the sensor controller 31 performs this detection after transitioning to local scan.

[0102] The sensor controller 31, having detected that the pen 2b supports both the old and new protocols, transmits a command COMDATA (transition command) to the pen 2b in the next uplink signal US1, instructing the pen 2b to transition to the new protocol. Upon receiving this command COMDATA, the pen 2b enters the new mode S12, as described with reference to FIG. 10. The sensor controller 31 then receives the downlink signal DS2 transmitted by the pen 2b that has entered the new mode S12, and performs re-pairing with the pen 2b using the new protocol, and transitions to state S21, in which the reception mode for the downlink signal DS in time slot TS1 becomes the new mode. Through the above procedure, communication with the pen 2b detected in time slot TS1 in state S20 transitions to the new protocol.

[0103] 14(b) shows a case where the pen 2b, which has entered the old mode S11 in response to an uplink signal US1 while the sensor controller 31 is in state S21, transmits a downlink signal DS1 using time slot TS2. Upon receiving this downlink signal DS1, the sensor controller 31 pairs with the pen 2b in time slot TS2 using the old protocol and transitions to state S24.

[0104] Thereafter, the sensor controller 31 detects that the pen 2b, with which it is paired in time slot TS2, supports both the old and new protocols from bit A (see FIG. 3(b)) included in the downlink signal DS1 transmitted by the pen 2b. The sensor controller 31 then transmits, in the next uplink signal US1, a command COMDATA (transition command) to instruct the pen 2, with which it is paired in time slot TS2, to transition to the new protocol. Having received this command COMDATA, the pen 2b enters the new mode S12, as described with reference to FIG. 10. The sensor controller 31 then receives the downlink signal DS2 transmitted by the pen 2b that has entered the new mode S12. The sensor controller 31 then performs re-pairing with the pen 2b using the new protocol, and transitions to state S23, where the reception mode for the downlink signal DS in time slot TS2 becomes the new mode. Through the above procedure, communication with the pen 2b detected in time slot TS2 in state S21 transitions to the new protocol.

[0105] 14(c) shows a case where the pen 2b, which has entered the old mode S11 in response to the uplink signal US1 while the sensor controller 31 is in state S22, transmits a downlink signal DS1 using time slot TS2. Upon receiving this downlink signal DS1, the sensor controller 31 pairs with the pen 2b in time slot TS2 using the old protocol and transitions to state S26.

[0106] Thereafter, the sensor controller 31 detects that the pen 2b, with which it is paired in time slot TS2, supports both the old and new protocols from bit A (see FIG. 3(b)) included in the downlink signal DS1 transmitted by the pen 2b. The sensor controller 31 then transmits, in the next uplink signal US1, a command COMDATA (transition command) to instruct the pen 2b, with which it is paired in time slot TS2, to transition to the new protocol. Having received this command COMDATA, the pen 2b enters the new mode S12, as described with reference to FIG. 10. The sensor controller 31 then receives the downlink signal DS2 transmitted by the pen 2b that has entered the new mode S12. The sensor controller 31 then performs re-pairing with the pen 2b using the new protocol, and transitions to state S25, where the reception mode for the downlink signal DS in time slot TS2 becomes the new mode. Through the above procedure, communication with the pen 2b detected in time slot TS2 in state S22 transitions to the new protocol.

[0107] As described above, according to this embodiment, even if the sensor controller 31 has paired with a pen 2b that supports the new protocol using the old protocol, it is possible to redo the pairing using the new protocol and start communication using the new protocol.

[0108] As described above, according to this embodiment, even if the pen 2a, which is compatible only with the old protocol, receives an uplink signal SUS in a special state (e.g., an uplink signal US2 according to the new protocol) from the sensor controller 31, it can operate based on the uplink signal NUS it has previously received. Furthermore, even if the pen 2b, which is compatible with both the old and new protocols, receives an uplink signal US1 during communication with the sensor controller 31 according to the new protocol, it can operate based on the uplink signal US2 it has previously received. Also, even if the pen 2b receives an uplink signal US2 during communication with the sensor controller 31 according to the old protocol, it can operate based on the uplink signal US1 it has previously received. Furthermore, the sensor controller 31 can detect both the downlink signal DS1 generated according to the old protocol and the downlink signal DS2 generated according to the new protocol in each of the frames F transmitting the uplink signal US1 and the frame F transmitting the uplink signal US2. Therefore, according to this embodiment, both the pen 2a and the pen 2b can be used simultaneously in one electronic device 3.

[0109] Furthermore, according to this embodiment, even if a pen 2b that supports the new protocol is paired using the old protocol, the pen 2b can be transitioned to the new mode S12 by sending a transition command from the sensor controller 31, so that communication can be performed using the new protocol with the pen 2b that supports the new protocol.

[0110] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0111] For example, in the above embodiment, a transition command was sent from the sensor controller 31 to transition the pen 2b that had entered the old mode S11 to the new mode S12, but the pen 2b may also transition to the new mode S12 autonomously.

[0112] 15 is a mode transition diagram of the pen 2b according to the first modified example of the embodiment of the present invention. As shown in the figure, when the pen 2b according to this modified example detects the uplink signal US2 while in the old mode S11, it transitions to the new mode S12 instead of the continuation mode S11a shown in FIG. 10. In the example of FIG. 15, the continuation mode S11a is not provided. Even in this case, the sensor controller 31 can communicate with the pen 2b using the new protocol.

[0113] Furthermore, in the above embodiment, the number of pens 2 that can be paired with the sensor controller 31 simultaneously is set to two, but the number of pens 2 that can be paired with the sensor controller 31 simultaneously is not limited to two.

[0114] 16 is a diagram showing a transmission (Tx) and reception (Rx) schedule in a sensor controller 31 according to a second modified example of an embodiment of the present invention. As shown in the figure, this modified example uses two reception channels Rx1 and Rx2 with different frequencies. Two time slots TS1 and TS2 are provided in reception channel Rx1, and two time slots TS3 and TS4 are provided in reception channel Rx2. Therefore, the total number of time slots available for transmitting downlink signals DS is four, and according to this modified example, the number of pens 2 that can be simultaneously paired with the sensor controller 31 is four.

[0115] In this modified example, the old protocol may be compatible with only the receiving channel Rx1, and the new protocol may be compatible with the receiving channels Rx1 and Rx2. In this case, it is preferable for the pen 2b compatible with the new protocol to use the time slots TS3 and TS4 preferentially. This makes it possible to use as many pens 2 as possible simultaneously.

[0116] Furthermore, the sensor controller 31 according to this modification preferably changes the transmission ratio of the uplink signals US1 and US2 depending on the coexistence of the downlink signal DS1 generated according to the old protocol and the downlink signal DS2 generated according to the new protocol. Specifically, it is preferable to change the ratio so that the transmission rate of the uplink signal US2 increases as the number of received downlink signals DS2 increases compared to the number of received downlink signals DS1.

[0117] Furthermore, in the above embodiment, only the transition command sent by the sensor controller 31 to transition communication with the pen 2b from the old protocol to the new protocol has been described, but the sensor controller 31 may also send a transition command to transition communication with the pen 2b from the new protocol to the old protocol.

[0118] In the above embodiment, when communication with the pen 2b is transitioned from the old protocol to the new protocol, the sensor controller 31 transmits a transition command by the uplink signal US1. However, the transition command may be transmitted by the uplink signal US2. In this case, even if the pen 2b has entered the old mode S11 or the old continuation mode S11a, it is preferable that the pen 2b first decodes the command signal COM in the uplink signal US2 and determines whether or not the transition command is included. If the transition command is included, it is preferable that the pen 2b executes an operation in accordance with the transition command, i.e., transitions to the new mode S12.

[0119] Furthermore, in the above embodiment, an example of applying the present invention to both new and old protocols (backward compatibility) has been described, but the present invention can also be applied to a multi-pen environment where different protocols coexist. For example, the present invention can be applied to two different protocols that, although different from each other, both determine the frame reference time by an uplink signal and share a portion of the signal. [Explanation of symbols]

[0120] 1. Position detection system 2, 2a, 2b pens 3 Electronic equipment 20 core body 21 Pen tip 22 Pen tip electrode 23 Pen pressure detection unit 26 Power supply 27 Integrated Circuits 30 Sensor Electrode 30X linear electrode 30X,30Y linear electrode 30Y linear electrode 31 Sensor Controller 32 panels 33 Electronic equipment control section 34 LCD display section 45 memory 60 MCU 61 Logic Section 62 Transmitter 63 Receiving unit 64 Selection section 80 Pattern supply unit 81 Switch 82 Code string holding section 83 Diffusion processing section 84 Transmission guard 85 Amplifier circuit 86 Detector circuit 87 Analog-to-Digital (AD) Converter 88x,88y switch 89x, 89y Conductor selection circuit AB bit COM command signal COMDATA command CRC error detection code ctrl_t1~ctrl_t4,ctrl_r control signals DATA Data signal DS downlink signal F Frame NUS Uplink signal US received correctly according to the old protocol P1,P2 indicated position PN spreading code PRE Preamble PS position signal RCRC Reverse Error Detection Code Rx1, Rx2 receiving channels S0 Discovery Mode S1 communication mode S0,S10 Discovery mode S11 Old Mode S11a Old Continuation Mode S12 New Mode S12a New Continuation Mode S1a Continuous Mode st1~st3 trajectory STA slot status information sTRx, sTRy, selX, selY control signals SUS Special Status Uplink Signal US TS, TS1~TS4 time slots US uplink signal US1 Uplink signal US generated according to the old protocol US2 Uplink signal US generated according to the new protocol

Claims

1. An integrated circuit for a pen configured to be able to receive both a first uplink signal generated in accordance with a first protocol and a second uplink signal generated in accordance with a second protocol different from the first protocol, after entering a second operation mode conforming to the second protocol in response to receiving the second uplink signal, transmitting a second downlink signal conforming to the second protocol when receiving the first uplink signal; Integrated circuit for pen.

2. transitioning to a discovery mode for discovering a sensor controller when the second uplink signal is not detected and only the first uplink signal is detected for a predetermined period of time during operation in the second operation mode; 10. An integrated circuit for a pen according to claim 1.

3. transitioning to the second operation mode when a command instructing entry into the second operation mode is received by the first or second uplink signal while operating in the first operation mode according to the first protocol; 10. An integrated circuit for a pen according to claim 1.

4. configured to, after entering a first operational mode according to the first protocol in response to receiving the first uplink signal, transmit a first downlink signal according to the first protocol; the first downlink signal includes flag information indicating whether the integrated circuit for the pen is an integrated circuit that supports only a first protocol or an integrated circuit for the pen is an integrated circuit that supports both the first and second protocols; 10. An integrated circuit for a pen according to claim 1.

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