Integrated circuit

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 known a system that realizes 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 is configured to periodically transmit an uplink signal, and the pen is configured to transmit a downlink signal in response to the uplink signal.

[0003] The uplink signal is a signal for notifying the pen of the start timing of a frame used for transmitting and receiving signals and a command for controlling the pen. The downlink signal is a signal including a position signal, which is an unmodulated carrier wave signal, and a data signal, which is a carrier wave signal modulated by data such as a writing pressure value. The sensor controller that receives the downlink signal 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 a 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 the sensor controller transmits an uplink signal at the beginning of each frame. In the example of Patent Document 3, pairing is performed by a pen that receives an uplink signal transmitting a response signal (ACK) within the same frame, and the sensor controller that receives this response signal notifying the pen of a temporarily used pen ID (local ID), time slot, and frequency 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, a position signal may be transmitted without a pen pressure value during pairing because the size of data to be shared between the pen and the sensor controller is large, it takes time for the pen to become in a state where it can transmit a pen pressure value, etc. For example, as in the example of Patent Document 2, when the pen needs to transmit a 52-bit unique ID for pairing, the free space of the data signal becomes insufficient, 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 may become unnatural at the beginning of the stroke. That is, if the electronic device is configured not to 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. Also, if the 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 far removed 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 portion 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 which perform pairing through bidirectional communication, and the pen periodically transmits an N-bit writing pressure value to the sensor controller. After the processing for the pairing is completed, the pen periodically transmits the writing pressure value, while during a period before the processing for the pairing is completed, the pen transmits an abbreviated writing pressure value consisting of the upper M bits of the writing pressure value which is shorter than the N bits, instead of the writing pressure value. It is.

[0011] The pen of the present invention is a pen that pairs with a sensor controller through bidirectional communication and periodically transmits an N-bit pen pressure value to the sensor controller, and after the processing for the pairing is completed, the pen periodically transmits the pen pressure value, while during the period before the processing for the pairing is completed, the pen transmits an abbreviated pen pressure value consisting of the upper M bits of the pen pressure value that are 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 pen pressure value from the pen.When a shortened pen pressure value consisting of an upper M-bit portion shorter than the N bits of the pen pressure value is received from the pen, the sensor controller acquires the pen pressure value by complementing the lower NM bits with a predetermined value. Effect 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 description 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. [Diagram 2] 2 is a diagram showing the internal configuration of each of a pen 2 and a tablet terminal 3. FIG. [Diagram 3] A diagram showing the structure of a frame used for transmitting and receiving uplink signals US and downlink signals DS. [Figure 4] 5(a) to 5(c) respectively show stroke data Sa to Sc when pen input is started in an unpaired state. [Diagram 5] 4 is a flow chart showing a process performed by a 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. [Figure 7] 8. (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 FIG. 8 when the shortened writing pressure value SPRD is as shown in (b). [Figure 8] 4 is a flow chart showing a process performed by a sensor controller 31. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment 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 the present 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 performing pen input to the tablet terminal 3, and is used to indicate a position on the panel surface 3a of the tablet terminal 3. A 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 electroluminescence 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 a display surface of the display device and a touch surface for pen input. The display device plays a role of 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) 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 direction and the Y direction 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, perform two-way communication. 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 be compatible with 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 portion related to position detection of the pen 2 is shown.

[0021] 2, the pen 2 is configured to have a core 20, a pen tip electrode 21, a writing pressure detection sensor 22, a circuit section 23, and a power source 24. As the power source 24, for example, a cylindrical AAAA battery is used.

[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 the 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 in advance to the pen 2.

[0024] Next, looking at 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, 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. The plurality of sensor electrodes 30X and the plurality of sensor electrodes 30Y are arranged so as to overlap in the Z direction, as shown in FIG. 2. Note that while the sensor electrodes 30X, 30Y are shown as plate-shaped conductors in FIG. 2, the actual sensor electrodes 30X, 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 later 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 multiple sensor electrodes 30X, 30Y.

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

[0028] The downlink signal DS is a signal including 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 required for pairing (for example, the above-mentioned pen ID, 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. The sensor controller 31 that receives the downlink signal DS 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 obtains the data transmitted by the pen 2 by demodulating the data signal. The position derived in this way and the data obtained 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 figure, the transmission and reception of the uplink signal US and the downlink signal DS in this embodiment is performed by time division multiplexing, and each frame F is 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 obtains 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 following multiple time slots TS in the same frame F as the received uplink signal US.

[0030] FIG. 3 shows a case where the pen 2 and the sensor controller 31 are newly paired. The pen 2 that is not paired with the sensor controller 31 continuously or intermittently receives the uplink signal US (marked as "R" in FIG. 2). As a result of this reception, the pen 2 that receives the uplink signal US transmitted at the beginning (time t1) of the illustrated frame F1 transmits a downlink signal DS using a time slot TS2 that is predetermined for the unpaired pen 2. At this time, the pen 2 places data for pairing in a 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 the 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, for example, the sensor controller 31 notifies the pen 2 of the determined one or more time slots TS by using an uplink signal US transmitted at the beginning (time t2) of frame F2. 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 onward. 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 a large volume of data, for example exceeding 50 bits, it may not be possible to transmit it all within one time slot TS. In that case, the pen 2 may transmit a downlink signal DS including the pairing data using a time slot TS2 for a plurality of 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 an uplink signal US.

[0033] Returning to Figure 2, the host processor 32 is a 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 of generating stroke data according to positions and data (including pen pressure values) sequentially supplied from the sensor controller 31. Specifically, the drawing application generates curves such as Bezier curves and Catmull-Rom curves based on a series of positions, and controls the line width or transparency of the generated curve according to the pen pressure value, thereby generating stroke data. The drawing application renders the generated stroke data and supplies it to the above-mentioned display device, 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] We have described above the basic configurations 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 describe in detail the processing performed by the pen 2 and the sensor controller 31 to prevent the line width and transparency of the starting portion of a stroke from becoming unnatural due to pairing.

[0036] First, the problem to be solved by the present invention will be described again with reference to FIG. 4. FIGS. 4(a) to (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 the 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 the 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 where all downlink signals DS include pen pressure values. In this case, the sensor controller 31 can normally acquire pen pressure values ​​corresponding to the positions P1 to P8. Here, as also 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 value. Therefore, if all pen pressure values ​​are normally acquired, natural writing of strokes according to human movement 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 needs to place a large amount of pairing data in the data signal constituting the downlink signal DS, and as a result, it may not be possible to place a pen pressure value in the data signal even if the pen tip is in contact with the panel surface 3a. In this case, the sensor controller 31 cannot obtain pen pressure values ​​corresponding to some positions (positions P1 and P2 in the example of FIG. 4(b)) that correspond to the start of writing a stroke, as exemplified 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 deviation (a deviation 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 Fig. 4(b). In other words, even though the user intends to write at positions P1 and P2, the stroke will be drawn only from position P3, which gives the user a sense of incongruity.

[0040] Fig. 4(c) shows one possible process for improving the case of Fig. 4(b). In this process, the host processor 32 regards the pen pressure value corresponding to the position P3 derived immediately after the positions P1 and P2 as the pen pressure value corresponding to the positions P1 and P2, and generates stroke data. According to this, the stroke data is also drawn at the positions P1 and P2 as shown in Fig. 4(c), which alleviates the above-mentioned problem of deviation, but the line width becomes unnatural at the beginning of the stroke.

[0041] The pen 2 and sensor controller 31 according to this embodiment solve the above problems 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 transmitting an abbreviated writing pressure value consisting of the upper M-bit portion of the writing pressure value that is shorter than N bits from the pen 2 to the sensor controller 31 during the period before the pairing process is completed. The pen 2 and the sensor controller 31 will be described in detail below with reference to their respective processing flows.

[0042] 5 is a flow diagram showing the process performed by the circuit unit 23 of the pen 2. The initial state of the process 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 executes an operation to receive an uplink signal US (step S1). Then, it is determined whether or not the uplink signal US has been received (step S2), and if it has not been received, it waits for reception of the uplink signal US by repeatedly executing the process 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 an operation of generating a downlink signal DS including the data. If the command is for notifying a local ID, the operation performed in step S3 is an operation of storing the local ID in memory. Furthermore, if the command specifies a time slot (or a frequency or a spreading code), the operation performed in step S3 is an operation of determining a transmission / reception schedule for the uplink signal US and the downlink signal DS, and storing information indicating the determined transmission / 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 subsequent uplink signal US and transmits the downlink signal DS based on the acquired timing and the transmission / reception schedule determined in step S3.

[0045] Next, the circuit unit 23 judges whether or not pairing with the sensor controller 31 has been completed (step S5). If the circuit unit 23 judges 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 is determined 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 according to the acquired transmission / reception schedule and frame start timing (step S8), and judges whether or not a pairing cancellation condition, such as the uplink signal US not being received for a predetermined period of time, is satisfied based on the result (step S9). If the sensor controller 31 judges that the condition is satisfied, it cancels the pairing (step S10) and returns to step S1 to continue the process. On the other hand, if the sensor controller 31 judges that the condition is not satisfied in step S9, it returns to step S3 to continue the process.

[0047] Fig. 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 contents of the data signal DATA differ 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. The other data includes 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 of the pen pressure value PRD. FIG. 7(b) shows an example of M = 5. In this way, 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 high.

[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 or not pairing has been established with the processing target pen 2 (step S26). The result of this determination becomes positive after information indicating that pairing has been established 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 as shown in FIG. 7(b). As shown in the figure, the sensor controller 31 is configured to derive the writing pressure value PRD by applying the shortened writing pressure value SPRD to the upper M bits of the N-bit writing pressure value PRD and complementing the lower NM bits with a predetermined value. The predetermined value to be complemented is preferably "0" as shown in the figure, but may be "1". The writing pressure value PRD derived in this way contains an error, but since the upper M bits are correct, it becomes a value (=1216) close to the correct writing pressure value PRD, as can be understood by comparing it with the correct writing pressure value PRD (=1238) shown in FIG. 7(a).

[0055] Return 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). As a specific example, the sensor controller 31 performs an operation of supplying 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 supplied. In addition, for example, when pairing data is received from the pen 2 in which pairing is being performed, the sensor controller 31 performs a process of storing the pairing data in memory, and when all necessary pairing data is received, further performs a process of storing information indicating that pairing has been completed in memory, and also performs a process of determining a time slot (or a frequency or a spreading code) to be assigned to the pen 2 to be processed, and placing data indicating the determined time slot (or a frequency or a spreading code) in the uplink signal US to be transmitted next. When the processing of steps S25 to S29 has been completed for all the pens 2 that have received the downlink signal DS, the sensor controller 31 returns to step S20 to continue the processing.

[0056] As described above, according to the system 1 of this embodiment, even if the pen 2 cannot transmit the N-bit pen pressure value PRD, it can transmit the shortened pen pressure value SPRD consisting of the upper M bits of the pen pressure value PRD. Therefore, it is possible to prevent the line width and transparency of the starting part of the 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 Pen 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 Shortened pen pressure value TS Time Slot US uplink signal

Claims

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

2. the first downlink signal includes a position signal and a first data signal including the pen pressure value; the second downlink signal includes a position signal and a second data signal including the reduced pen 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 that is predetermined for unpaired pens; 10. The integrated circuit of claim 1.

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