Integrated circuit

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, electronic devices having large touch surfaces, such as electronic whiteboards, are increasingly being used for simultaneous operation (drawing) with multiple electronic pens.

[0003] Patent Document 1 discloses an example of a sensor controller that realizes simultaneous drawing with two electronic pens. The sensor controller in this example assigns a different local ID to each of two detected electronic pens, and includes the local ID in a command signal, thereby enabling each electronic pen 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] US Patent Publication No. 2015 / 0256329 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the protocol of 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 the others support only the old protocol (hereinafter referred to as the "old protocol"). Therefore, it has been necessary to make it possible to use both an electronic pen that supports both the old and new 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") in one electronic device.

[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 configured to receive an uplink signal generated in accordance with a first protocol, and transmit a downlink signal based on the reception timing of the uplink signal and a command placed in the uplink signal, and if, after receiving the uplink signal, during a period in which it is possible to receive a next uplink signal, the next uplink signal is not normally received and an uplink signal in a special state is received, the pen transmits the downlink signal in accordance with the first protocol, or including default data.

[0009] A pen according to another aspect of the present invention is 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, and after entering a second operating mode according to the second protocol in response to receiving the second uplink signal, when the pen receives the first uplink signal, transmits a second downlink signal according to the second protocol.

[0010] A sensor controller according to the present invention is a sensor controller configured to be capable of detecting both a first downlink signal generated according to a first protocol and a second downlink signal generated according to a second protocol different from the first protocol, and configured to alternately set a first frame for transmitting a first uplink signal for the first protocol and a second frame 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 frame. Effect of the Invention

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

[0012] [Figure 1] 1 is a diagram showing an overall configuration of a position detection system 1 according to an embodiment of the present invention. [Diagram 2] 4 is a diagram showing a schedule of transmission (Tx) and reception (Rx) in the sensor controller 31. FIG. [Diagram 3] FIG. 1 is a diagram showing the configuration of a downlink signal DS. [Figure 4] FIG. 2 is a diagram showing the configuration of an uplink signal US. [Diagram 5] FIG. 2 is a diagram showing the internal configuration of the pen 2. [Figure 6] 2 is a diagram showing the internal configuration of the electronic device 3. FIG. [Figure 7] FIG. 1A is a diagram showing an example of the configuration of an uplink signal US1, and FIGS. 1B to 1G are diagrams showing example configurations of an uplink signal US2. [Figure 8] FIG. 1A shows an example of a spreading code constituting a preamble PRE used in an old protocol, and FIG. 1B shows an example of a spreading code constituting a preamble PRE used in a new protocol. [Figure 9] FIG. 13 is a mode transition diagram of the old pen, pen 2a. [Figure 10] This is a mode transition diagram for pen 2b, which is a new pen. [Figure 11] FIG. 4 is a mode transition diagram of the sensor controller 31. [Figure 12] 10 is a diagram for explaining mode transition of the sensor controller 31. FIG. [Figure 13] 10 is a diagram for explaining mode transition of the sensor controller 31. FIG. [Figure 14] 11 is an explanatory diagram for explaining a procedure for transitioning communication with a pen 2b paired with an old protocol to a new protocol. FIG. [Figure 15] FIG. 11 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. 11 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 PREFERRED EMBODIMENTS

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

[0014] 1 is a diagram showing an overall configuration of a position detection system 1 according to the present 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 an active electrostatic method and can be used simultaneously or separately by one or more users. Hereinafter, when there is no need to distinguish between the pens 2a and 2b, they may be collectively referred to as the pens 2.

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

[0017] The transmission and reception of the uplink signal US and the downlink signal DS are performed according to a predetermined protocol, but this protocol may be changed due to technological advances, etc. In the following, a protocol that is newly launched at a certain point in time is referred to as a new protocol (second protocol), and the protocol that was used up until that point is referred to as an old protocol (first protocol). The explanation will be continued assuming that the pen 2a is an electronic pen (old pen) that supports only the old protocol, and the pen 2b is an electronic pen (new pen) that supports both the old and new protocols.

[0018] To give an overview of an input operation 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 FIG. 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 of the electronic device 3. FIG. 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 FIG. 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 later, the sensor controller 31 receives this downlink signal DS via the sensor electrode 30, thereby acquiring the position of the pen 2 on the touch surface, and acquiring the data transmitted by the pen 2. The position and data acquired 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 position and data thus supplied, and outputs the data to the liquid crystal display unit 34 after rendering, thereby drawing the above-mentioned trajectory on the touch surface.

[0020] 2 is a diagram showing a schedule of transmission (Tx) and reception (Rx) in the sensor controller 31. As shown in the figure, the sensor controller 31 is configured to transmit an uplink signal US and receive a downlink signal DS in units of frames F. In each frame F, the transmission of the uplink signal US and the reception of the downlink signal DS are executed 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 reception time slots TS1 and TS2 are provided in one frame F. In the following, when there is no need to particularly distinguish between the time slots TS1 and TS2, they may be collectively referred to as time slots 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, two time slots TS1 and TS2 are provided, so that up to two pens 2 can transmit downlink signals DS in one frame F. This means that the number of pens 2 that can be paired with the sensor controller 31 at the same time is up to two. However, as exemplified in FIG. 16 described later, the number of pens 2 that can be paired with the sensor controller 31 at the same time is not limited to two. The time slots TS used by each pen 2 are determined when the sensor controller 31 and the pen 2 perform pairing.

[0022] 3 is a diagram 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 the position signal PS as the 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 over the entire touch surface. This position detection is referred to as "global scan" in this specification. A specific method of position detection by 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 a data signal DATA as a downlink signal DS in addition to the above-mentioned position signal PS. 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 of 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 includes 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 having 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 the support status for the new protocol. Bit A only needs to be included in the downlink signal DS generated according to the old protocol, and does not have to be included in the downlink signal DS generated according to 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) composed of chips with a predetermined chip width (for example, 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 performs a detection operation of the spread code constituting the preamble PRE, detects the presence of the sensor controller 31 when it detects the preamble PRE, and synchronizes with the sensor controller 31 based on the timing of detecting the preamble PRE. The synchronization here means that 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) are determined based on the timing of detecting the preamble PRE. The pen 2 is configured to update this synchronization every time it receives the uplink signal US.

[0029] The command signal COM includes a local ID (LID) indicating the pen 2 which is the destination of this command signal COM, a command COMDATA including instructions for the pen 2, and slot status information STA which indicates 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 found the sensor controller 31, it checks the availability of the time slots TS1 and TS2 by referring to the slot status information STA. If any of the time slots TS is available as a result, the pen 2 uses that time slot TS to transmit a downlink signal DS including only the position signal PS. The sensor controller 31 receives this downlink signal DS and 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 to be transmitted. When the pen 2 receives this uplink signal US, it detects that it has been detected by the sensor controller 31 by detecting the change in the slot status information STA, and also obtains a predetermined local ID (for example, 0 for time slot TS1, 1 for time slot TS2, etc.) corresponding to the time slot TS from which the downlink signal DS was transmitted, and stores it in its own memory.

[0032] When the pen 2 that has stored the local ID subsequently receives and decodes an uplink signal US, it first refers to the local ID in the command signal COM and judges whether it matches the local ID stored in its own memory 45, thereby judging whether the uplink signal US was sent to itself. If it is judged as an uplink signal US sent to itself as a result of this judgment, the pen 2 extracts the command COMDATA from the command signal COM and performs processing according to the contents. This processing includes a process of acquiring data requested to be transmitted by the sensor controller 31 and placing it in the next or subsequent downlink signal DS. On the other hand, if it is judged that the uplink signal US was not sent to itself, the pen 2 transmits a default downlink signal DS including a position signal PS and a data signal DATA including only a pen pressure value, without acquiring 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 electrode 30. The indicated 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 the movement of the indicated positions P1 and P2. The sensor controller 31 is also configured to acquire data (such as writing pressure value) transmitted by the pen 2 by receiving a data signal DATA using the sensor electrode 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 to form 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 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 through this abutment. In a typical example, the writing pressure detection unit 23 is configured by a variable capacitance module whose capacitance changes according 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 constituted by, 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 a process of receiving an uplink signal US via the pen tip electrode 22, and a process of generating a downlink signal DS based on the received uplink signal US and transmitting it 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 described below is received after entering the communication mode S1. Hereinafter, an uplink signal US in a special state is referred to as an "uplink signal SUS," and an uplink signal US that is normally received according to the old protocol is referred to as an "uplink signal NUS."

[0041] On the other hand, although details will be described later with reference to Fig. 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 a discovery mode S10 for discovering the sensor controller 31, an old mode S11 (first operation mode) for communicating with the discovered sensor controller 31 by 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 operation mode) for communicating with the discovered sensor controller 31 by 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 is referred to as an "uplink signal US1", and the uplink signal US generated according to the new protocol is 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 the 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. More specifically, the MCU 60 is a microprocessor that has an internal ROM and RAM and operates based on a predetermined program. The processing performed by the MCU 60 includes, in addition to the processing for controlling the logic unit 61, the processing for 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 the processing for deriving the coordinates x, y of the pen 2 based on the downlink signal DS supplied from the reception unit 63, receiving the data Res transmitted by the pen 2, and outputting it to the electronic device control unit 33 together with the local ID of the pen 2. On the other hand, 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 the uplink signal US and receive the downlink signal DS according to the transmission and reception schedule shown in FIG. 2. Details will be described later with reference to FIG. 11, but the MCU 60 has three transmission modes of the uplink signal US: a new and old mixed mode, an old only mode, and a new only mode. When the MCU 60 is in the new and 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 (for example, 1:1). On the other hand, when the MCU 60 is in the old only mode, the MCU 60 is configured to transmit the uplink signal US1 for the old protocol in all frames F. Also, when the MCU 60 is in the new only mode, the MCU 60 is configured to transmit the uplink signal US2 for the new protocol in all frames 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: a discovery mode, an old mode, and a 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 according to 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 according to the new protocol. Hereinafter, the downlink signal DS generated according to the old protocol is referred to as a "downlink signal DS1", and the downlink signal DS generated according to the new protocol is 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 the frame F in which the uplink signal US1 is transmitted, and may detect both the downlink signals DS1 and DS2 in the frame F in which the uplink signal US2 is transmitted.

[0049] FIG. 7(a) is a diagram showing an example of the configuration of the uplink signal US1, and FIGS. 7(b)-(g) are diagrams showing examples of the configuration of the 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 protocols. The content of these differences is not particularly limited, and various aspects are possible. FIGS. 7(b)-(g) show six of such aspects. Each will be described in detail below.

[0050] FIG. 7(b) is 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 pen 2b, which is the new pen, can determine whether the uplink signal US is the 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 pen 2a, which is the old pen, determines that the uplink signal US has been received normally if bit B has the first value after decoding the received uplink signal US, but determines that an abnormality has been 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 above-mentioned uplink signal NUS, and in the latter case, the received uplink signal US is determined to be the above-mentioned uplink signal SUS in the special state.

[0051] The uplink signal US2 in FIG. 7(b) can be used, for example, when there is a reserved field in the uplink signal US1. The value of the reserved field does not have a specific meaning, but usually has a specific value (for example, "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 (for example, "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 an 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 by inverting that portion, thereby being able to determine 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 as a result of inverting the extracted portion and performing error detection, and can determine that it has received the uplink signal US1 if no error is detected as a result of performing error detection without inverting the extracted portion. On the other hand, in the pen 2a, which is the old pen, if an 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 an 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, when the decoded result is a code word, or when it is not a code word and an inverted value is included in the CRC field, the pen 2a determines that the received uplink signal US is the above-mentioned uplink signal NUS, and when the decoded result is not a code word, the pen 2a determines that the received uplink signal US is the above-mentioned uplink signal SUS in the special state. 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 FIG. 7(b).

[0053] FIG. 7(d) is an example in which the preamble PRE of the new protocol is longer than the preamble PRE of the old protocol, FIG. 7(e) is an example in which the new protocol does not have an error detection code CRC unlike the old protocol, FIG. 7(f) is an example in which the time length of the command signal COM of the new protocol is shorter than the time length of the command signal COM of the old protocol due to multi-values, and FIG. 7(g) is an example in which the new protocol does not have an error detection code CRC unlike the old protocol and the time length of the command signal COM of the new protocol is shorter than the time length of the command signal COM of the old protocol due to multi-values, etc. In either case, the pen 2b, which is the new pen, can determine whether the uplink signal US is the uplink signal US1 or US2 by attempting to decode the received uplink signal US assuming that it is each of the uplink signals US1 and US2. On the other hand, the pen 2a, which is the old pen, decodes the uplink signal US only as the uplink signal US1, and therefore an abnormal result is obtained 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 uplink signal SUS in a special state.

[0054] In addition, when different preambles PRE are used between the old protocol and the new protocol as in the example shown in FIG. 7(d), the preambles PRE may be configured so that only a part 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)), the partial match of the code (chip sequence) constituting the spreading code (including a match in which the result of the correlation calculation is equal to or greater than a predetermined value), or the leading part of the preamble PRE composed of a pattern of a plurality of spreading codes. In this case, when the pen 2a, which is the old pen, detects this partial match in addition to obtaining an abnormal decoding result, it may determine that the received uplink signal US is the uplink signal SUS in the above-mentioned special state. This makes it possible to prevent the pen 2a from determining that the uplink signal SUS in the special state has been received even in the case of a decoding error caused by noise.

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

[0056] Returning to Fig. 6, the transmission 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 transmission unit 62 in this embodiment, but it may be included in the MCU 60.

[0057] The pattern supplying unit 80 is a functional unit that outputs symbols constituting the preamble PRE in accordance with an instruction of a control signal ctrl_t1 supplied from the logic unit 61. The symbols constituting the preamble PRE are composed of symbols dedicated to the preamble that do not correspond to any of 0 to 15, for example.

[0058] The switch 81 plays a role of selecting either the pattern supplying unit 80 or the MCU 60 based on a control signal ctrl_t2 supplied from the logic unit 61, and supplying the output of the selected one to the spreading processing unit 83. When the switch 81 selects the pattern supplying unit 80, symbols constituting the preamble PRE are supplied from the pattern supplying unit 80 to the spreading processing unit 83. On the other hand, when the switch 81 selects the MCU 60, a command signal COM and an error detection code CRC are supplied from the MCU 60 to the spreading processing unit 83. The command signal COM and the error detection code CRC supplied to the spreading processing unit 83 are each composed of a string 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 for each type of symbol is held in the code sequence holding unit 82. 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 a 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 the transmission guard unit 84.

[0061] The transmission guard unit 84 has the function of inserting a guard period (a period during which neither transmission nor reception is performed) required to switch between the transmission period of the uplink signal US and the reception period of the downlink signal DS based on a 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 includes 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 selection unit 64. The detection 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 detection 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 multiple 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 multiple 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 selection unit 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 realizes the transmission of the uplink signal US and the reception of the downlink signal DS by controlling the selection unit 64 using these control signals sTRx, sTRy, selX, and selY.

[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 in progress in the time slot TS in which the position signal PS is received. In a time slot TS in which pairing is not in progress, the logic unit 61 controls the selection unit 64 so that all of the linear electrodes 30X, 30Y are sequentially connected to the input terminal of the receiving unit 63 within the duration of the time slot TS. In this way, the MCU 60 can obtain the reception strength of the position signal PS in each of all the linear electrodes 30X, 30Y, and it becomes possible to detect the position of the pen 2 over the entire touch surface (global scan). On the other hand, in a time slot TS in which pairing is not in progress, 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 is continuing. In this way, 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 a data signal DATA included in a 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 derived from the immediately preceding position signal PS for the pen 2 transmitting the data signal DATA 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 described above the configurations of the pen 2 and electronic device 3 that constitute the position detection system 1, as well as the uplink signal US and downlink signal DS. Next, we will describe 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 of the old pen, pen 2a. As shown in the figure, pen 2a is configured to operate in any one of discovery mode S0, communication mode S1, and continuation mode S1a.

[0074] The discovery mode S0 is a mode for discovering the sensor controller 31. The pen 2a that has entered the discovery mode S0 performs an operation of detecting the uplink signal US intermittently or continuously. Then, when the uplink signal NUS is received, the pen 2a determines a transmission / reception schedule of the uplink signal US and the downlink signal DS based on the reception timing, and transitions to the communication mode S1. On the other hand, when the uplink signal SUS is received, the pen 2a stays in the 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 according to the transmission / reception schedule. Specifically, the transmission / reception schedule is updated according to the reception timing of the received uplink signal NUS, and the downlink signal DS is transmitted according to the updated transmission / reception schedule. The downlink signal DS thus transmitted is a signal that the pen 2a generates according to the old protocol, and includes data instructed to be transmitted 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 left the sensor controller 31 and returns to the discovery mode S0. If the uplink signal SUS is received without normally 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 reception timing of the uplink signal SUS. Specifically, the pen 2a transmits a downlink signal DS including data according to a 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, when the uplink signal NUS is received, the pen 2a returns to the communication mode S1, and when the uplink signal SUS is detected n times or more (n is any natural number equal to or greater than 2) consecutively (i.e., the uplink signal NUS is not detected) and when 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 of 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] The discovery mode S10 is a mode for discovering the sensor controller 31, similar to the discovery mode S0 of the pen 2a shown in Fig. 9. The pen 2b that has entered the discovery mode S10 executes the detection operation of the uplink signal US intermittently or continuously. Then, when the uplink signal US1 is received, the transmission / reception schedule of the uplink signal US and the downlink signal DS is determined based on the reception timing, and the mode transitions to the old mode S11. On the other hand, when the uplink signal US2 is received, the transmission / reception schedule of the uplink signal US and the downlink signal DS is determined based on the reception timing, and the mode transitions to the new mode S12.

[0081] The pen 2b that 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 according to the transmission / reception schedule. Specifically, the transmission / reception schedule is updated according to the reception timing of the received uplink signal US (including the uplink signals US1 and US2), and the downlink signal DS is transmitted according to the updated transmission / reception schedule. The downlink signal DS thus transmitted is a signal that the pen 2b generates according to 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 left 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 reception timing of 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 received up to that point, or predetermined data such as a pen pressure value.

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

[0085] Here, when the command COMDATA arranged 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 shown 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 by 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 according to the transmission / reception schedule. Specifically, the transmission / reception schedule is updated according to the reception timing of the received uplink signal US (including the uplink signals US1 and US2), and the downlink signal DS is transmitted according to the updated transmission / reception schedule. The downlink signal DS thus transmitted is a signal that the pen 2b generates according to 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 pen 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 left 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 continue 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 received up to that point, or predetermined data such as the pen pressure value.

[0089] On the other hand, when the uplink signal US2 is received, the pen 2b returns to the new mode S12. Also, when the uplink signal US1 is detected n or more times (n is any natural number equal to or greater than 2, for example) consecutively (i.e., the uplink signal US2 is not detected), and when 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 figure, the sensor controller 31 has a reception mode of the downlink signal DS for each time slot TS, and also has a transmission mode of the uplink signal US. The former includes a discovery mode, an old mode, and a new mode, and the latter includes a new and old mixed mode, an old only mode, and a new only mode. 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] 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 modes, and the transmission mode of the uplink signal US is a mixed new and old mode. In this case, the sensor controller 31 alternates between a frame F for transmitting an uplink signal US1 for the old protocol and a frame F for 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] Fig. 12(a) shows a case where a downlink signal DS2 is received in a time slot TS1 in a frame F in which an uplink signal US2 is transmitted, when the sensor controller 31 is in a state S20. The pen 2 that transmits the first downlink signal DS2 in response to the uplink signal US2 is the 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 by the new protocol, and sets the reception mode of the downlink signal DS in the time slot TS1 to the new mode (state S21 in Fig. 11). As a result, communication by the new protocol is performed in the time slot TS1.

[0093] FIG. 12(b) shows a case where the downlink signal DS2 is received in the time slot TS2 in the frame F in which the uplink signal US2 was transmitted when the sensor controller 31 is in the state S21. The pen 2 transmitting this downlink signal DS2 is also the pen 2b (a different pen 2b from the pen 2b transmitting the downlink signal DS2 in the time slot TS1. The same applies below.) and entered the new mode S12 shown in FIG. 10 at the time of transmitting the downlink signal DS. The sensor controller 31 pairs with the pen 2 transmitting the detected downlink signal DS2 by the new protocol, sets the reception mode of the downlink signal DS in the 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 by the new protocol in both the 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 the downlink signal DS1 is received in the time slot TS2 in the frame F in which the uplink signal US1 is transmitted when the sensor controller 31 is in the state S21. The pen 2 transmitting this downlink signal DS1 can be either the pen 2a or the pen 2b. If it is the pen 2a, it has entered the communication mode S1 shown in FIG. 9 at the time of transmitting the downlink signal DS1. On the other hand, if it is the pen 2b, it has entered the old mode S11 shown in FIG. 10 at the time of transmitting the downlink signal DS1. The sensor controller 31 pairs with the pen 2 that transmitted the detected downlink signal DS1 by the old protocol, and sets the reception mode of the downlink signal DS in the time slot TS2 to the old mode (state S24 in FIG. 11). As a result, communication is performed by the new protocol in the time slot TS1, and communication is performed by the old protocol in the time slot TS2.

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

[0096] Fig. 13(b) shows a case where the downlink signal DS2 is received in the time slot TS2 in the frame F in which the uplink signal US2 was transmitted when the sensor controller 31 is in the state S22. The pen 2 transmitting this downlink signal DS2 is the 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 by the new protocol, and sets the reception mode of the downlink signal DS in the time slot TS2 to the new mode (state S25 in Fig. 11). As a result, communication is performed by the old protocol in the time slot TS1, and communication is performed by the new protocol in the time slot TS2.

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

[0098] Here, according to the above operation, even if the pen 2 to be paired is a pen 2b compatible with 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 started using the old protocol. Therefore, when communication is started using the old protocol, the sensor controller 31 judges whether the pen 2 is compatible with the new protocol by referring to bit A (see FIG. 2) included in the downlink signal DS1, and if it is judged that the pen 2 is compatible, a transition command that instructs transition to communication using the new protocol is placed in the uplink signal US1 to be transmitted next. This point will be described in detail below with reference to FIG. 14.

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

[0100] 14(a) shows a case where 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 the time slot TS1. The sensor controller 31, which has received this downlink signal DS1, pairs with the pen 2b in the time slot TS1 using the old protocol and transitions to state S22.

[0101] After that, the sensor controller 31 detects that the 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, which has detected that the pen 2b supports both the old and new protocols, transmits a command COMDATA (transition command) to the pen 2b instructing the pen 2b to transition to the new protocol, by the next uplink signal US1 that is transmitted. The pen 2b that has received this command COMDATA enters the new mode S12, as described with reference to FIG. 10. Then, the sensor controller 31, which has received the downlink signal DS2 transmitted by the pen 2b that has entered the new mode S12, performs re-pairing with the pen 2b in the new protocol, and transitions to state S21, in which the reception mode of 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 upon receiving the uplink signal US1 while the sensor controller 31 is in state S21, transmits a downlink signal DS1 using the time slot TS2. The sensor controller 31, which has received this downlink signal DS1, pairs with the pen 2b in the time slot TS2 using the old protocol and transitions to state S24.

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

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

[0106] After that, the sensor controller 31 detects that the pen 2b supports both the old protocol and the new protocol from bit A (see FIG. 3(b)) included in the downlink signal DS1 transmitted by the pen 2b during pairing in the time slot TS2. Then, the sensor controller 31 transmits a command COMDATA (transition command) to the pen 2b during pairing in the time slot TS2 by the next uplink signal US1 to instruct the pen 2b during pairing in the time slot TS2 to transition to the new protocol. The pen 2b that receives this command COMDATA enters the new mode S12 as described with reference to FIG. 10. Then, the sensor controller 31 receives the downlink signal DS2 transmitted by the pen 2b that has entered the new mode S12, performs re-pairing with the pen 2b using the new protocol, and transitions to a state S25 in which the reception mode of the downlink signal DS in the time slot TS2 becomes the new mode. Through the above procedure, communication with the pen 2b detected in the time slot TS2 in the 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 that supports only the old protocol receives an uplink signal SUS in a special state (for example, an uplink signal US2 according to the new protocol) from the sensor controller 31, it can operate based on the uplink signal NUS that has been received up to that point. Furthermore, the pen 2b that supports both the old and new protocols can operate based on the uplink signal US2 that has been received up to that point during communication with the sensor controller 31 according to the new protocol, even if it receives the uplink signal US1, and can operate based on the uplink signal US1 that has been received up to that point during communication with the sensor controller 31 according to the old protocol, even if it receives the uplink signal US2. 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 frame F that transmits the uplink signal US1 and the frame F that transmits the uplink signal US2. Therefore, according to this embodiment, it is possible to use both the pen 2a and the pen 2b 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, making it possible to communicate with the pen 2b that supports the new protocol using 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, the sensor controller 31 sends a transition command to transition the pen 2b that has entered the old mode S11 to the new mode S12, but the pen 2b may also autonomously transition to the new mode S12.

[0112] Fig. 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 way, the sensor controller 31 can communicate with the pen 2b by the new protocol.

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

[0114] 16 is a diagram showing a schedule of transmission (Tx) and reception (Rx) in the sensor controller 31 according to the second modified example of the embodiment of the present invention. As shown in the figure, in this modified example, two receiving channels Rx1 and Rx2 having different frequencies are used. Two time slots TS1 and TS2 are provided in the receiving channel Rx1, and two time slots TS3 and TS4 are provided in the receiving channel Rx2. Therefore, the number of time slots available for transmitting the downlink signal DS is four in total, and therefore, 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 preferentially use the time slots TS3 and TS4. This makes it possible to use as many pens 2 as possible at the same time.

[0116] Moreover, the sensor controller 31 according to this modification preferably changes the transmission ratio of the uplink signals US1, 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 becomes higher as the number of received downlink signals DS2 is greater than that of the downlink signal DS1.

[0117] In addition, in the above embodiment, the transition command transmitted by the sensor controller 31 has been described as a transition command for transitioning communication with the pen 2b from the old protocol to the new protocol, but the sensor controller 31 may also transmit a transition command for transitioning 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 to be transitioned from the old protocol to the new protocol, the sensor controller 31 transmits a transition command by the uplink signal US1, but 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 according to the transition command, that is, transition to the new mode S12.

[0119] In the above embodiment, an example of applying the present invention to old and new protocols (backward compatibility) has been described, but the present invention can also be applied to a multi-pen environment in which different protocols coexist. For example, the present invention can also be applied to two different protocols that are different from each other but in which the frame reference time is determined by the uplink signal and part of the signal is common. [Explanation of symbols]

[0120] 1 Position Detection System 2,2a,2b pen 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 Panel 32 33 Electronic equipment control section 34 LCD display section 45 Memory 60 MCU 61 Logic Section 62 Transmitter 63 Receiving section 64 Selection section 80 Pattern supply unit 81 Switch 82 Code string holding section 83 Diffusion Processing Unit 84 Transmission guard section 85 Amplification 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 normally received 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 channel 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 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 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; 2. 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 conforming to the first protocol; 2. An integrated circuit for a pen according to claim 1.

4. configured to transmit a first downlink signal according to the first protocol after entering a first operational mode according to the first protocol in response to receiving the first uplink signal; 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; 2. An integrated circuit for a pen according to claim 1.

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