Integrated Circuits

Abstract

To prevent a line width and transparency of a writing start part of a stroke from becoming unnatural due to pairing.SOLUTION: An integrated circuit is used in a pen that performing pairing with a sensor controller through bidirectional communication via a pen tip electrode. After processing for the pairing is completed, the integrated circuit periodically transmits a first downlink signal including an N-bit pen pressure value via the pen tip electrode, whereas during a period before the processing for the pairing is completed, the integrated circuit transmits a second downlink signal including an abbreviated pen pressure value consisting of an upper M-bit portion shorter than the N bits of the pen pressure value via the pen tip electrode.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] There is a known system that enables pen input to an electronic device such as a tablet terminal by performing bidirectional communication between a pen and a sensor controller. In this type of system, the sensor controller periodically transmits an uplink signal, and the pen transmits a downlink signal in response to the uplink signal.

[0003] The uplink signal is a signal that notifies the pen of the start timing of a frame used for transmitting and receiving signals and commands for controlling the pen. The downlink signal is a signal that includes a position signal, which is an unmodulated carrier wave signal, and a data signal, which is a carrier wave signal modulated with data such as a writing pressure value. Upon receiving the downlink signal, the sensor controller detects the position of the pen based on the reception strength of the position signal at each of the multiple sensor electrodes arranged on the touch surface, and obtains the data transmitted by the pen by demodulating the data signal. Of the data thus obtained, the writing pressure value is used to control the line width or transparency of the stroke drawn based on the detected position.

[0004] When new pen input is started in the above system, a process (hereinafter referred to as "pairing") is executed between the pen and the sensor controller to share a pen ID and various communication parameters. Patent documents 1 to 3 disclose examples of this pairing. In the example of Patent document 1, pairing is executed by transmitting configuration data including a stylus identifier from the pen to the sensor controller, and transmitting channel data specifying a frequency and a time slot from the sensor controller to the pen. In the example of Patent document 2, pairing is executed by transmitting a unique ID, which is 52-bit information that differs for each pen, from the pen to the sensor controller.

[0005] Patent Document 3 describes that communication between the pen and the sensor controller is performed in frame units, and that the sensor controller transmits an uplink signal at the beginning of each frame. In the example of Patent Document 3, pairing is performed by the pen receiving the uplink signal transmitting a response signal (ACK) within the same frame, and the sensor controller receiving this response signal notifying the pen of the pen ID (local ID), time slot, and frequency to be temporarily used using the uplink signal of the next frame. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 139861 [Patent Document 2] International Publication No. 2018 / 029855 [Patent Document 3] U.S. Patent No. 9,977,519 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when performing the above-mentioned pairing, there may be cases where a position signal is transmitted without a pen pressure value during pairing because the size of the data to be shared between the pen and the sensor controller is large, and it takes time for the pen to become able to transmit a pen pressure value. For example, as in the example of Patent Document 2, when the pen needs to transmit a 52-bit unique ID for pairing, there is insufficient free space for the data signal, and therefore the pen pressure value cannot be transmitted during pairing.

[0008] If a position signal without a pen pressure value is transmitted in this way, the line width and transparency of the stroke at the beginning of the stroke may become unnatural. For example, if an electronic device is configured to not draw a stroke until a pen pressure value is received, a discrepancy may occur between the original start position of the stroke and the start position of the stroke that is actually drawn. Furthermore, if an electronic device is configured to compensate for a missed pen pressure value with a later received pen pressure value, the stroke may be drawn with a pen pressure value that is far different from the original pen pressure value.

[0009] Therefore, one object of the present invention is to provide a system including a pen and a sensor controller, a pen, and a sensor controller that can prevent the line width and transparency of the starting part of a stroke from becoming unnatural due to pairing. [Means for solving the problem]

[0010] The system according to the present invention includes a pen and a sensor controller that are paired through bidirectional communication, and the pen periodically transmits an N-bit writing pressure value to the sensor controller. After the pairing process is completed, the pen periodically transmits the writing pressure value, while during the period before the pairing process is completed, the pen transmits an abbreviated writing pressure value consisting of the upper M-bit portion of the writing pressure value that is shorter than the N bits. is.

[0011] The pen according to the present invention is a pen that pairs with a sensor controller through bidirectional communication and periodically transmits an N-bit writing pressure value to the sensor controller. After the pairing process is completed, the pen periodically transmits the writing pressure value, while during the period before the pairing process is completed, the pen transmits an abbreviated writing pressure value consisting of the upper M-bit portion of the writing pressure value that is shorter than the N bits.

[0012] The sensor controller according to the present invention is a sensor controller that pairs with a pen through bidirectional communication and periodically receives an N-bit writing pressure value from the pen. When a shortened writing pressure value consisting of the upper M bits of the writing pressure value, which is shorter than the N bits of the writing pressure value, is received from the pen, the sensor controller acquires the writing pressure value by complementing the lower NM bits with a predetermined value. [Effects of the Invention]

[0013] According to the present invention, even if the pen cannot transmit an N-bit pressure value, it can transmit an abbreviated pressure value consisting of the upper M bits of the pressure value, thereby making it possible to prevent the line width and transparency of the starting part of the stroke from becoming unnatural due to pairing. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a configuration of a system 1 according to an embodiment of the present invention. [Figure 2] 2 is a diagram showing the internal configuration of each of the pen 2 and the tablet terminal 3. FIG. [Figure 3] 1 shows the structure of a frame used to transmit and receive uplink signals US and downlink signals DS. [Figure 4] (a) to (c) respectively show stroke data Sa to Sc when pen input is started in an unpaired state. [Figure 5] 10 is a flowchart showing the processing performed by the circuit section 23 of the pen 2. FIG. [Figure 6] 5. (a) is a diagram showing the downlink signal DS transmitted by the circuit unit 23 in step S6 of FIG. 5, and (b) is a diagram showing the downlink signal DS transmitted by the circuit unit 23 in step S7 of FIG. 5. [Figure 7] (a) is a diagram showing an example of the structure of a writing pressure value PRD, (b) is a diagram showing the structure of a shortened writing pressure value SPRD corresponding to the writing pressure value PRD shown in (a), and (c) is a diagram showing the writing pressure value PRD derived in step S28 of Figure 8 when the shortened writing pressure value SPRD is the one shown in (b). [Figure 8] 4 is a flowchart showing processing performed by the sensor controller 31. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] 1 is a diagram showing the configuration of a system 1 according to this embodiment. As shown in the figure, the system 1 includes a pen 2 and a tablet terminal 3.

[0017] The pen 2 is a position indicator for pen input to the tablet terminal 3, and is used to indicate a position on the panel surface 3a of the tablet terminal 3. The user inputs various figures and characters as shown in the figure by sliding the pen tip of the pen 2 on the panel surface 3a.

[0018] The tablet terminal 3 is a computer with a built-in display device such as a liquid crystal display or an organic EL display. Instead of the tablet terminal 3, a notebook or desktop personal computer, or a smartphone may be used. The panel surface 3a of the tablet terminal 3 serves as both the display surface of the display device and a touch surface for pen input. The display device plays a role in visually outputting figures and characters input by the user using the pen 2 on the panel surface 3a under the control of a host processor 32 (see FIG. 2), which will be described later. In the following description, the horizontal direction of the panel surface 3a as seen by the user is referred to as the X direction, the depth direction is referred to as the Y direction, and the direction perpendicular to the X and Y directions is referred to as the Z direction.

[0019] The tablet terminal 3 detects the pen 2 using a method in which the pen 2 and a sensor controller 31 (see FIG. 2), which will be described later, communicate bidirectionally. Specific examples of such methods include an active electrostatic method and an electromagnetic induction method. The following description will be given on the assumption that the active electrostatic method is used. The tablet terminal 3 may also support input by a finger (touch input), in which case finger detection is performed using, for example, a capacitance method.

[0020] 2 is a diagram showing the internal configuration of each of the pen 2 and the tablet terminal 3. However, with regard to the internal configuration of the tablet terminal 3, only the parts related to position detection of the pen 2 are shown.

[0021] 2, the pen 2 is configured to include a core 20, a pen tip electrode 21, a writing pressure detection sensor 22, a circuit section 23, and a power supply 24. The power supply 24 may be, for example, a cylindrical AAAA battery.

[0022] The lead 20 is a rod-shaped member arranged so that its longitudinal direction coincides with the pen axis direction of the pen 2. A conductive material is applied to the surface of the tip of the lead 20, forming a pen tip electrode 21. The rear end of the lead 20 abuts against the writing pressure detection sensor 22. The writing pressure detection sensor 22 serves to detect the pressure (writing pressure) applied to the tip of the lead 20.

[0023] The circuit unit 23 is an integrated circuit that performs various processes described below by reading and executing programs stored in its built-in memory, and is configured with a function of receiving an uplink signal US transmitted from the panel surface 3a of the tablet terminal 3 via the pen tip electrode 21, and a function of transmitting a downlink signal DS toward the panel surface 3a of the tablet terminal 3 via the pen tip electrode 21. In addition to the above programs, the built-in memory of the circuit unit 23 also stores a pen ID that has been assigned to the pen 2 in advance.

[0024] Next, focusing on the tablet terminal 3, the tablet terminal 3 is configured to include a sensor 30, a sensor controller 31, and a host processor 32.

[0025] The sensor 30 is a touch sensor embedded under the panel surface 3a and includes a plurality of sensor electrodes 30X and 30Y that are capacitively coupled to the pen tip electrode 21. The plurality of sensor electrodes 30X each extend in the Y direction and are juxtaposed at a constant pitch in the X direction. The plurality of sensor electrodes 30Y each extend in the X direction and are juxtaposed at a constant pitch in the Y direction. As shown in FIG. 2, the plurality of sensor electrodes 30X and the plurality of sensor electrodes 30Y are arranged to overlap in the Z direction. Note that while FIG. 2 shows the sensor electrodes 30X and 30Y as plate-shaped conductors, the actual sensor electrodes 30X and 30Y may be conductors of other shapes, such as mesh conductors.

[0026] The sensor controller 31 is an integrated circuit that performs various processes described below by reading and executing programs stored in an internal memory, and is configured to have a function of receiving a downlink signal DS transmitted by the pen 2 via the sensor 30, and a function of transmitting an uplink signal US toward the pen 2 via the sensor 30. As shown in Fig. 2, the sensor controller 31 is individually connected to each of the plurality of sensor electrodes 30X, 30Y.

[0027] Here, the uplink signal US is a signal that the sensor controller 31 sends to the pen 2 to notify it of the start timing of a frame used for transmitting and receiving signals, and a command for controlling the pen 2. The commands include a command that specifies a time slot (described later) within the frame, a command that specifies data to be transmitted by the pen 2, and the like. Upon receiving the uplink signal US, the pen 2 obtains a transmission and reception schedule for the uplink signal US and the downlink signal DS in accordance with the command contained therein, and generates a downlink signal DS, and transmits the generated downlink signal DS and receives the next uplink signal US in accordance with the obtained transmission and reception schedule.

[0028] The downlink signal DS is a signal that includes a position signal, which is an unmodulated carrier signal (burst signal), and a data signal, which is a carrier signal modulated by data to be transmitted to the sensor controller 31. The data transmitted by the data signal includes various data necessary for pairing (e.g., the pen ID described above, hereinafter referred to as "pairing data") and a writing pressure value indicating the value of the writing pressure detected by the writing pressure detection sensor 22. Upon receiving the downlink signal DS, the sensor controller 31 derives the position of the pen 2 on the panel surface 3a based on the reception strength of the position signal at each of the sensor electrodes 30X and 30Y, and also acquires the data transmitted by the pen 2 by demodulating the data signal. The position thus derived and the acquired data are sequentially supplied from the sensor controller 31 to the host processor 32.

[0029] FIG. 3 is a diagram showing the structure of a frame used for transmitting and receiving an uplink signal US and a downlink signal DS. As can be seen from the diagram, in this embodiment, the uplink signal US and the downlink signal DS are transmitted and received using time division multiplexing, with each frame F being divided into n time slots TS. Note that frequency division multiplexing or code division multiplexing may be used instead of or in addition to time division multiplexing. The sensor controller 31 transmits the uplink signal US in the first time slot TS1 of each frame F. The pen 2 acquires the time position of the frame F and each time slot TS by receiving the uplink signal US, and transmits the downlink signal DS using some or all of the subsequent time slots TS in the same frame F as the received uplink signal US.

[0030] FIG. 3 shows a case where a pen 2 and a sensor controller 31 are newly paired. A pen 2 that is not paired with the sensor controller 31 continuously or intermittently receives an uplink signal US (denoted by "R" in FIG. 2). As a result of this reception, the pen 2 receives the uplink signal US transmitted at the beginning (time t1) of the illustrated frame F1. The pen 2 then transmits a downlink signal DS using a time slot TS2 predetermined for unpaired pens 2. At this time, the pen 2 places pairing data in the data signal that constitutes the downlink signal DS. The pen 2 also starts receiving the uplink signal US at time t2, which is the start timing of frame F2.

[0031] The sensor controller 31 receives pairing data from an unpaired pen 2, stores the received pairing data, and determines one or more time slots TS to be assigned to the pen 2. Then, it notifies the pen 2 of the determined one or more time slots TS, for example, by using an uplink signal US transmitted at the beginning of frame F2 (time t2). Upon receiving this notification, the pen 2 determines that pairing is complete, and transmits a downlink signal DS using the notified one or more time slots TS from frame F2 onwards. The sensor controller 31 determines that pairing is complete by receiving the downlink signal DS transmitted in this manner.

[0032] Here, since the pairing data is large data, for example exceeding 50 bits, it may not be possible to transmit it all within one time slot TS. In this case, the pen 2 may transmit a downlink signal DS including the pairing data using time slots TS2 for multiple frames F. In this case, after receiving all of the pairing data, the sensor controller 31 may determine one or more time slots TS to be assigned to the pen 2 that has transmitted the pairing data, and notify the same using the uplink signal US.

[0033] Returning to Figure 2, the host processor 32 is the central processing unit of the tablet terminal 3, and plays a role in executing the operating system and various applications of the tablet terminal 3 by reading and executing programs stored in a storage device (not shown).

[0034] The applications executed by the host processor 32 include a drawing application. The drawing application plays a role in generating stroke data according to positions and data (including pen pressure values) sequentially supplied from the sensor controller 31. Specifically, the drawing application generates stroke data by generating curves such as Bézier curves and Catmull-Rom curves based on a series of positions and controlling the line width or transparency of the generated curve according to the pen pressure value. The drawing application renders the generated stroke data and supplies it to the display device described above, thereby drawing strokes on the panel surface 3a shown in FIG. 1. The drawing application also generates digital ink including the generated stroke data, stores it in a storage device (not shown), and transmits it to another computer.

[0035] The above describes the basic configuration of the pen 2 and the tablet terminal 3, and the basic processing performed by the pen 2 and the sensor controller 31. Next, we will explain in detail the processing performed by the pen 2 and the sensor controller 31 to prevent the line width and transparency of the starting part of a stroke from becoming unnatural due to pairing.

[0036] First, the problem to be solved by the present invention will be explained again with reference to FIG. 4. FIGS. 4(a) to 4(c) respectively show stroke data Sa to Sc when pen input is started from an unpaired state. Positions P1 to P8 shown in each figure indicate positions derived by the sensor controller 31 based on position signals sequentially transmitted from the pen 2. The size of the circle corresponding to each of positions P1 to P8 represents the magnitude of the pen pressure value at that time (the value of the pen pressure detected by the pen pressure detection sensor 22 of the pen 2). Here, an example will be described in which the sensor controller 31 controls the line width of the stroke data by deriving the envelope of these circles, but the same applies to a case in which the sensor controller 31 controls the transparency of the stroke data based on the pen pressure value.

[0037] FIG. 4(a) shows an ideal case in which all downlink signals DS contain pen pressure values. In this case, the sensor controller 31 can correctly acquire the pen pressure values corresponding to each of positions P1 to P8. As shown in FIG. 4(a), the sensor controller 31 is configured to control the line width of the stroke data by deriving the envelope of a circle representing the pen pressure values. Therefore, if all pen pressure values are correctly acquired, natural strokes corresponding to human movements will be expressed, as in the stroke data Sa shown in FIG. 4(a).

[0038] FIG. 4(b) shows a case where the downlink signal DS corresponding to positions P1 and P2 does not include a pen pressure value. As described above, the pen 2 during pairing must include a large amount of pairing data in the data signal that constitutes the downlink signal DS. As a result, it may not be possible to include a pen pressure value in the data signal even though the pen tip is in contact with the panel surface 3a. In this case, the sensor controller 31 will not be able to obtain pen pressure values corresponding to some positions that correspond to the start of a stroke (positions P1 and P2 in the example of FIG. 4(b)), as shown in FIG. 4(b).

[0039] In such a case, if the host processor 32 does not draw a stroke until the pen pressure value can be acquired, a discrepancy (a discrepancy of the distance D shown in the figure) will occur between the start position of the original stroke and the start position of the stroke that is actually drawn, as shown in Figure 4(b). In other words, even though the user intended to draw at positions P1 and P2, the stroke will only be drawn from position P3, which gives the user a sense of incongruity.

[0040] Figure 4(c) shows one possible process for improving the case of Figure 4(b). In this process, the host processor 32 regards the pen pressure value corresponding to position P3, which is derived immediately after positions P1 and P2, as the pen pressure value corresponding to positions P1 and P2, and generates stroke data. This alleviates the problem of discrepancy because stroke data is also drawn at positions P1 and P2, as shown in Figure 4(c), but results in unnatural line widths at the start of the stroke.

[0041] The pen 2 and sensor controller 31 according to this embodiment solve the above problem by periodically transmitting an N-bit writing pressure value from the pen 2 to the sensor controller 31 after the pairing process is completed, and by transmitting an abbreviated writing pressure value consisting of the upper M-bit portion of the writing pressure value, which is shorter than N bits, from the pen 2 to the sensor controller 31 during the period before the pairing process is completed. Below, a detailed explanation will be given with reference to the processing flows of the pen 2 and the sensor controller 31.

[0042] 5 is a flow diagram showing the processing performed by the circuit unit 23 of the pen 2. The initial state of the processing shown in the figure is a state in which the pen 2 and the sensor controller 31 are not paired. As shown in the figure, the circuit unit 23 first performs an operation to receive an uplink signal US (step S1). Then, it determines whether or not the uplink signal US has been received (step S2). If the uplink signal US has not been received, it waits for reception of the uplink signal US by repeatedly executing the processing of step S1.

[0043] On the other hand, if it is determined in step S2 that the uplink signal US has been received, the circuit unit 23 executes an operation according to the command contained in the uplink signal US (step S3). For example, if the command instructs transmission of certain data, the operation performed in step S3 is to generate a downlink signal DS including that data. If the command notifies a local ID, the operation performed in step S3 is to store the local ID in memory. Furthermore, if the command specifies a time slot (or a frequency or spreading code), the operation performed in step S3 is to determine a transmission and reception schedule for the uplink signal US and the downlink signal DS, and to store information indicating the determined transmission and reception schedule and information indicating that pairing has been completed in memory.

[0044] The circuit unit 23 further acquires the start timing of the frame based on the reception timing of the uplink signal US (step S4). The circuit unit 23 receives the uplink signal US and transmits the downlink signal DS thereafter based on the acquired timing and the transmission / reception schedule determined in step S3.

[0045] Next, the circuit unit 23 determines whether or not pairing with the sensor controller 31 has been completed (step S5). If the circuit unit 23 determines that pairing has not been completed, it transmits a downlink signal DS including an abbreviated writing pressure value and pairing data in accordance with the acquired transmission / reception schedule and frame start timing (step S6). The abbreviated writing pressure value will be described in detail later. On the other hand, if it determines in step S5 that pairing has been completed, the circuit unit 23 transmits a downlink signal DS including a writing pressure value in accordance with the acquired transmission / reception schedule and frame start timing (step S7).

[0046] After completing step S6 or step S7, the circuit unit 23 executes a receiving operation of the uplink signal US in accordance with the acquired transmission / reception schedule and frame start timing (step S8), and based on the result, determines whether a pairing cancellation condition, such as not receiving the uplink signal US for a predetermined period of time, is satisfied (step S9). If the sensor controller 31 determines that the condition is satisfied, it cancels the pairing (step S10) and returns to step S1 to continue processing. On the other hand, if the sensor controller 31 determines that the condition is not satisfied in step S9, it returns to step S3 to continue processing.

[0047] 6(a) is a diagram showing the downlink signal DS transmitted by the circuit unit 23 in step S6, and FIG. 6(b) is a diagram showing the downlink signal DS transmitted by the circuit unit 23 in step S7. As shown in these diagrams, both downlink signals DS include a position signal PS and a data signal DATA, but the content of the data signal DATA differs between steps S6 and S7.

[0048] Specifically, the data signal DATA (second data signal) transmitted in step S6 includes the reduced writing pressure value SPRD and pairing data PAIRD, whereas the data signal DATA (first data signal) transmitted in step S7 includes the writing pressure value PRD and other data, including data indicating the on / off state of a switch provided on the surface of the pen 2.

[0049] FIG. 7(a) is a diagram showing an example of the structure of the pen pressure value PRD, and FIG. 7(b) is a diagram showing the structure of the shortened pen pressure value SPRD corresponding to the pen pressure value PRD shown in FIG. 7(a). As shown in FIG. 7(a), the pen pressure value PRD is N-bit data (N is a natural number of 2 or more), and in this example, N = 11. Then, as shown in FIG. 7(b), the shortened pen pressure value SPRD is composed of the upper M bits (1 ≦ M < N) shorter than N bits among the pen pressure values PRD. FIG. 7(b) shows an example of M = 5. Thus, the shortened pen pressure value SPRD is obtained by extracting only the upper M bits from the original pen pressure value PRD. As a result, even when the pairing data PAIRD has to be transmitted, the possibility of transmission is increased.

[0050] FIG. 8 is a flowchart showing the processing performed by the sensor controller 31. As shown in the figure, the sensor controller 31 first transmits an uplink signal US in the time slot TS at the head of the frame (step S20), and executes the reception operation of the downlink signal DS in each subsequent time slot (step S21). Then, it is determined whether there is a pen 2 that meets the pairing release condition such as the downlink signal DS not being received for a predetermined period (step S22). If it is determined that there is, the pairing with the pen 2 that satisfies the release condition is released (step S23).

[0051] If it is determined in step S22 that there is no pen 2 that meets the pairing release condition, or when step S23 is completed, the sensor controller 31 executes the processing of steps S25 to S29 for each pen 2 that has received the downlink signal DS (step S24).

[0052] Specifically, the sensor controller 31 first derives the position of the processing target pen 2 based on the reception strength of the position signal PS at each of the sensor electrodes 30X, 30Y (see FIG. 2) (step S25). Next, the sensor controller 31 determines whether pairing with the processing target pen 2 has been completed (step S26). The result of this determination becomes positive after information indicating that pairing has been completed is stored in memory in step S29, which will be described later.

[0053] If the sensor controller 31 determines in step S26 that pairing has been completed, it acquires the writing pressure value PRD by extracting it from the data signal DATA (step S27), and proceeds to step S29. On the other hand, if the sensor controller 31 determines in step S26 that pairing has not been completed, it performs a process of deriving the writing pressure value PRD based on the shortened writing pressure value SPRD included in the data signal DATA (step S28), and then proceeds to step S29.

[0054] FIG. 7(c) is a diagram showing the writing pressure value PRD derived in step S28 when the shortened writing pressure value SPRD is the one shown in FIG. 7(b). As shown in the figure, the sensor controller 31 is configured to derive the writing pressure value PRD by assigning the shortened writing pressure value SPRD to the upper M bits of the N-bit writing pressure value PRD and complementing the lower N M bits with a predetermined value. The predetermined value to be complemented is preferably "0" as shown in the figure, but may also be "1." The writing pressure value PRD derived in this way will contain an error, but since the upper M bits are correct, it will be a value (=1216) close to the correct writing pressure value PRD, as can be seen by comparing it with the correct writing pressure value PRD (=1238) shown in FIG. 7(a).

[0055] Returning to FIG. 8 , in step S29, the sensor controller 31 executes an operation according to the position derived in step S25, the pen pressure value PRD acquired or derived in steps S27 and S28, and other data included in the data signal (step S29). To give a specific example, the sensor controller 31 supplies the derived position and the acquired or derived pen pressure value to the host processor 32. The host processor 32 generates stroke data based on the position and pen pressure value thus provided. Furthermore, for example, when pairing data is received from a pen 2 in which pairing is being performed, the sensor controller 31 stores the pairing data in memory. When all necessary pairing data has been received, the sensor controller 31 further stores information indicating that pairing has been completed in memory, determines a time slot (or frequency or spread code) to be assigned to the pen 2 to be processed, and assigns data indicating the determined time slot (or frequency or spread code) to the uplink signal US to be transmitted next. When the processing of steps S25 to S29 has been completed for all pens 2 that have received the downlink signal DS, the sensor controller 31 returns to step S20 and continues the processing.

[0056] As described above, according to the system 1 of this embodiment, even if the pen 2 cannot transmit the N-bit pressure value PRD, it can transmit the shortened pressure value SPRD consisting of the upper M bits of the pressure value PRD. This makes it possible to prevent the line width and transparency of the starting part of a stroke from becoming unnatural due to pairing.

[0057] 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. [Explanation of symbols]

[0058] 1 System 2 pens 3. Tablet devices 3a Panel surface 20 cores 21 Pen tip electrode 22 Pen pressure detection sensor 23 Circuit section 24 Power supply 30 sensors 30X Sensor Electrodes 30X, 30Y sensor electrodes 31 Sensor Controller 32 host processor DATA Data signal DS downlink signal F Frame P1~P8 position PAIRD Pairing data PRD pen pressure value PS position signal Sa~Sc stroke data SPRD Reduced pressure value TS Time Slot US uplink signal

Claims

1. An integrated circuit used in a pen that pairs with a sensor controller through bidirectional communication via a pen tip electrode, After the pairing process is completed, a first downlink signal including an N-bit writing pressure value is periodically transmitted via the pen tip electrode; During a period before the pairing process is completed, a second downlink signal including a shortened writing pressure value consisting of a most significant M-bit portion of the writing pressure value that is shorter than the N bits is transmitted via the pen tip electrode. Integrated circuit.

2. the first downlink signal includes a position signal and a first data signal including the writing pressure value; the second downlink signal includes a position signal and a second data signal including the shortened writing pressure value; 10. The integrated circuit of claim 1.

3. the second data signal includes data necessary for the pairing; 3. The integrated circuit of claim 2.

4. The data required for the pairing is at least a part of a pen ID written in advance in the pen.

4. The integrated circuit of claim 3.

5. transmitting the second downlink signal using a time slot predetermined for unpaired pens; 10. The integrated circuit of claim 1.

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