Sensor controller and method

Abstract

To achieve both improving the accuracy of detecting coordinates of an electrode in contact with a panel surface, and improving the accuracy of detecting coordinates of an electrode not in contact with the panel surface.SOLUTION: A sensor controller according to the present invention determines whether or not a pen is in contact based on data received from the pen via short-range wireless communication, and when it is determined that the pen is in contact, performs a first scan to select a plurality of first reference positions that are evenly spaced from a plurality of reference positions that are evenly spaced and to detect a signal level of a position signal at each of the plurality of selected first reference positions, and when it is determined that the pen is not in contact, performs a second scan to select a plurality of second reference positions that are evenly spaced at intervals wider than the plurality of first reference positions among the plurality of reference positions and to detect a signal level of a position signal at each of the plurality of selected second reference positions.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method implemented by a sensor controller for detecting the coordinates of a pen that includes electrodes for transmitting signals, to said sensor controller and to an electronic device including said sensor controller. [Background technology]

[0002] A touchpad, which is provided on a notebook personal computer or the like, is a type of pointing device used to specify a position on the screen. A user can operate a mouse pointer by sliding a finger over the panel surface of the touchpad.

[0003] In the past, touch pads were used exclusively for input by fingers, but in recent years, use of touch pads for pen input has been considered. Patent Document 1 discloses an example of a notebook personal computer in which the touch pad is also used for pen input. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-154482 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when performing pen input on a touchpad, the panel surface needs to be associated with the entire screen, and the result of the pen input on the panel surface is then enlarged and displayed on the screen. In order to obtain the same coordinate detection accuracy for pen input on a touchpad as for pen input on a screen, it has been considered to make the spacing of the sensor electrodes placed under the panel surface to detect the position signal from the pen closer than when they are placed under the screen. This has the effect of improving the accuracy of coordinate detection for at least the electrodes in contact with the panel surface (such as the pen tip electrode in contact with the panel surface) among the electrodes provided on the pen.

[0006] However, as a result of extensive research, the inventors of the present application have found that configuring a touchpad with closely spaced sensor electrodes can actually worsen coordinate detection accuracy. Specifically, it has been found that the detection accuracy of the coordinates of electrodes that are not in contact with the panel surface (such as the pen tip electrode during hover and the second electrode for tilt detection) can worsen. This is believed to be because the position signal transmitted by the pen spreads over the panel surface, making it difficult to obtain a clear peak.

[0007] Therefore, one object of the present invention is to provide a method, a sensor controller, and an electronic device that can improve both the coordinate detection accuracy of electrodes in contact with a panel surface and the coordinate detection accuracy of electrodes not in contact with the panel surface. [Means for solving the problem]

[0008] A method according to the present invention is a method executed by a sensor controller that detects coordinates of a pen including one or more electrodes that transmit signals, and includes: a first scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is in contact with a panel surface at each of three or more first reference positions at which a signal level can be detected from the signal detected in a group of sensor electrodes included in a first range among a plurality of juxtaposed reference positions; a second scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is not in contact with the panel surface at each of three or more second reference positions at which a signal level can be detected from the signal detected in a group of sensor electrodes included in a second range among the plurality of reference positions that is wider than the first range; a first derivation step of deriving coordinates based on the signal level at each of the three or more first reference positions of the signal detected in the first scanning step; and a second derivation step of deriving coordinates based on the signal level at each of the three or more second reference positions of the signal detected in the second scanning step.

[0009] The sensor controller according to the present invention is a sensor controller that detects the coordinates of a pen that includes one or more electrodes that transmit signals, and executes the following steps: a first scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is in contact with a panel surface, at each of three or more first reference positions where a signal level can be detected from the signal detected in a group of sensor electrodes included in a first range among a plurality of juxtaposed reference positions; a second scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is not in contact with the panel surface, at each of three or more second reference positions where a signal level can be detected from the signal detected in a group of sensor electrodes included in a second range among the plurality of reference positions that is wider than the first range; a first derivation step of deriving coordinates based on the signal level of the signal detected in the first scanning step at each of the three or more first reference positions; and a second derivation step of deriving coordinates based on the signal level of the signal detected in the second scanning step at each of the three or more second reference positions.

[0010] The electronic device according to the present invention is an electronic device including a pen and a sensor controller that detects coordinates of the pen, wherein the pen includes one or more electrodes that each transmit a signal, and the sensor controller executes a first scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is in contact with a panel surface at each of three or more first reference positions at which a signal level can be detected from the signal detected in a group of sensor electrodes included in a first range among a plurality of juxtaposed reference positions, a second scanning step of detecting a signal transmitted from an electrode of the one or more electrodes that is not in contact with the panel surface at each of three or more second reference positions at which a signal level can be detected from the signal detected in a group of sensor electrodes included in a second range among the plurality of reference positions that is wider than the first range, a first derivation step of deriving coordinates based on the signal level of the signal detected in the first scanning step at each of the three or more first reference positions, and a second derivation step of deriving coordinates based on the signal level of the signal detected in the second scanning step at each of the three or more second reference positions. Effect of the Invention

[0011] According to the present invention, it is possible to capture signals from electrodes that are not in contact with the panel surface over a wider range, making it possible to simultaneously improve the accuracy of coordinate detection of electrodes that are in contact with the panel surface and the accuracy of coordinate detection of electrodes that are not in contact with the panel surface. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a state in which an electronic device 1 according to an embodiment of the present invention is used. [Diagram 2] 2 is a diagram showing the internal configuration of each of the pen 2 and the computer 3. FIG. [Diagram 3] FIG. 11 is a process flow diagram showing a reception process of a downlink signal DS executed by the sensor controller 31 during a local scan. [Figure 4]4(a) is a process flow diagram showing details of the first scan performed in step S3 of FIG. 3, and (b) is a process flow diagram showing details of the second scan performed in step S6 of FIG. 3. [Diagram 5] 4(b) is a diagram showing a first example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a); and FIG. 4(c) is a diagram showing a second example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a). [Figure 6] 4(b) is a diagram showing a first example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a); and FIG. 4(c) is a diagram showing a second example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a). [Figure 7] 4(b) is a diagram showing a first example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a); and FIG. 4(c) is a diagram showing a second example of a reference position selected in step S17 of FIG. 4(b) when the correspondence between the reference position and the sensor electrode 30X is as shown in FIG. 4(a). [Figure 8] FIG. 4 is a process flow diagram showing a more specific example of the reception process shown in FIG. 3. [Figure 9] 13 is a diagram showing measurement results of the signal level of the position signal transmitted from the rear end electrode 22 at each reference position in the X direction when the inclination θ of the pen 2 is 0°. FIG. [Figure 10] 13 is a diagram showing measurement results of the signal level of the position signal transmitted from the rear end electrode 22 at each reference position in the Y direction when the inclination θ of the pen 2 is 0°. FIG. [Figure 11] 13 is a diagram showing measurement results of the signal level of the position signal transmitted from the rear end electrode 22 at each reference position in the Y direction when the inclination θ of the pen 2 is 30°. FIG. [Figure 12] 1A is a diagram showing the trajectory of the position of the rear electrode 22 when the tip of the pen 2 is slid on the panel surface 12a while maintaining θ=0° in a comparative example to which the present invention is not applied, and FIG. 1B is a diagram showing the trajectory of the position of the rear electrode 22 when the tip of the pen 2 is slid on the panel surface 12a while maintaining θ=0° in an embodiment to which the present invention is applied. [Figure 13] FIG. 11 is a process flow diagram showing a reception process of a downlink signal DS executed by a sensor controller 31 during a local scan according to a 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 a state in which an electronic device 1 according to an embodiment of the present invention is in use. As shown in the figure, the electronic device 1 includes a pen 2 and a computer 3.

[0015] The pen 2 is a position indicator that inputs position information to the computer 3, and is used by the user to indicate a position on the panel surface 12a of the touch pad 12. The position indicated by the pen 2 becomes an input to the computer 3.

[0016] The computer 3 is a notebook personal computer and includes a display 10, a keyboard 11, and a touchpad 12. The display 10 is a display device having a display screen such as a liquid crystal display or an organic EL display, and serves to visually output characters and figures.

[0017] The keyboard 11 and the touch pad 12 are each an input device that allows a user to input data to the computer 3. Of these, the touch pad 12 functions as an input device by detecting the position of a finger or pen 2 on the panel surface 12a and outputting the position to a host processor 32 (see FIG. 2), which will be described later. In the following description, the horizontal direction of the panel surface 12a as viewed 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.

[0018] The touch pad 12 detects the position of the finger by, for example, a capacitive method. The pen 2 is detected by, for example, an active electrostatic method. The following description will be given on the assumption that the active electrostatic method is used, but the present invention is also applicable to cases where the pen 2 is detected by other methods, such as an electromagnetic induction method.

[0019] The pen 2, which supports the active electrostatic method, is configured to be able to transmit and receive signals bidirectionally to and from the touch pad 12 through built-in electrodes (a tip electrode 21 and a rear electrode 22 shown in FIG. 2, which will be described later). Hereinafter, a signal transmitted from the touch pad 12 to the pen 2 is referred to as an uplink signal US, and a signal transmitted from the pen 2 to the touch pad 12 is referred to as a downlink signal DS.

[0020] The touchpad 12 also has a function of detecting a click operation. Specifically, the click operation may be detected by detecting a tap operation on the touch surface with a pressure sensor (not shown) (pressure pad), or a push button switch may be arranged on the underside of the panel surface 12a, and the panel surface 12a itself may be displaced downward in response to a user's press to press the push button switch, thereby detecting a click operation (click pad). Alternatively, a separate button for clicking may be provided near the panel surface 12a, and a click operation may be detected by pressing the button.

[0021] 2 is a diagram showing the internal configuration of each of the pen 2 and the computer 3. However, with regard to the internal configuration of the computer 3, only the part related to the position detection of the pen 2 is shown.

[0022] 2, the pen 2 is configured to have a core 20, a tip electrode 21, a rear electrode 22, a writing pressure detection sensor 23, a circuit section 24, and a power source 25. As the power source 25, for example, a cylindrical AAAA battery is used.

[0023] 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 to form a tip electrode 21 (pen tip electrode). Note that the tip electrode 21 does not necessarily have to be arranged on the surface of the most distal end of the lead 20. In that case, a state may arise in which the most distal end of the lead 20 is in contact with the panel surface 12a but the tip electrode 21 is not in contact with the panel surface 12a, and the "tip electrode 21 in contact" in this embodiment includes a tip electrode 21 in such a state.

[0024] The rear end of the lead 20 abuts against the writing pressure detection sensor 23. The writing pressure detection sensor 23 serves to detect the pressure (writing pressure) applied to the tip of the lead 20. A rear end electrode 22 (a second electrode for detecting tilt) is provided at the rear end of the lead 20 (a position closer to the rear end of the pen 2 than the tip electrode 21). The rear end electrode 22 is a ring-shaped (donut-shaped) conductor, and is positioned so that the lead 20 passes through a hole in the center of the rear end electrode 22.

[0025] The circuit section 24 has a function of receiving an uplink signal US transmitted from the panel surface 12a of the touchpad 12 via the front electrode 21, and a function of transmitting a downlink signal DS toward the panel surface 12a of the touchpad 12 via the front electrode 21 or the rear electrode 22. These signals will be described in detail later.

[0026] Next, looking at the computer 3, the computer 3 is configured with a sensor 30, a sensor controller 31, and a host processor 32 shown in Fig. 2. Of these, the sensor 30 and the sensor controller 31 are components of the touchpad 12, and the host processor 32 is a central processing unit of the computer 3.

[0027] The sensor 30 is a touch sensor embedded under the panel surface 12a, and includes a plurality of sensor electrodes 30X, 30Y that are capacitively coupled to the front electrode 21 and the rear electrode 22, respectively. The plurality of sensor electrodes 30X extend in the Y direction and are juxtaposed at a constant pitch P in the X direction. The plurality of sensor electrodes 30Y extend in the X direction and are juxtaposed at a constant pitch P 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, although 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.

[0028] The pitch P is set to a value smaller than the pitch of sensor electrodes embedded under a screen in a tablet terminal or the like that supports pen input on the screen (hereinafter referred to as the "conventional pitch"). In a typical example, the pitch P is about 1 / 3 of the conventional pitch. This makes it possible for the touchpad 12 to detect the coordinates of the tip electrode 21 in contact with the panel surface 12a with higher accuracy than when the sensor electrodes 30X, 30Y are arranged at the conventional pitch.

[0029] 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.

[0030] The uplink signal US is a signal that includes an instruction (command) for the pen 2 and also serves to notify the pen 2 of the start of a schedule determined by a signal transmission / reception protocol. The sensor controller 31 is configured to transmit the uplink signal US using at least one of the multiple sensor electrodes 30X and the multiple sensor electrodes 30Y, and the pen 2 is configured to receive the uplink signal US using the tip electrode 21. Having received the uplink signal US, the pen 2 performs an operation in accordance with the command contained therein.

[0031] The commands transmitted by the uplink signal US include a command to specify a signal transmission / reception protocol to be used for transmitting and receiving signals to and from the pen 2, a command to specify data (hereinafter referred to as "pen data") to be transmitted by the pen 2 to the sensor controller 31, etc. The pen data includes a value indicating the writing pressure detected by the writing pressure detection sensor 23. After receiving the command to specify the signal transmission / reception protocol, the pen 2 receives an uplink signal US and transmits a downlink signal DS according to the schedule determined by the specified signal transmission / reception protocol and the start time of the schedule notified by the uplink signal US.

[0032] The downlink signal DS includes a downlink signal DS transmitted from the front electrode 21 and a downlink signal DS transmitted from the rear electrode 22. The former downlink signal DS includes a position signal for causing the sensor controller 31 to detect the position of the front electrode 21, and a data signal for transmitting pen data. The position signal is, for example, an unmodulated carrier signal (burst signal), and the data signal is a carrier signal modulated by the pen data to be transmitted. The latter downlink signal DS includes a position signal for causing the sensor controller 31 to detect the position of the rear electrode 22. This position signal is also, for example, an unmodulated carrier signal (burst signal).

[0033] The downlink signal DS transmitted from the front electrode 21 and the downlink signal DS transmitted from the rear electrode 22 are multiplexed and transmitted so that the sensor controller 31 can distinguish between them when receiving them. As a multiplexing method, various methods such as time division multiplexing, frequency division multiplexing, and code division multiplexing can be used, but the following description will be continued assuming that time division multiplexing is used.

[0034] The sensor controller 31 is configured to detect coordinates indicating the position of the tip electrode 21 on the panel surface 12a by receiving a position signal when receiving a downlink signal DS transmitted from the tip electrode 21, and to obtain pen data transmitted by the pen 2 by receiving a data signal. On the other hand, when receiving a downlink signal DS transmitted from the rear electrode 22, the sensor controller 31 is configured to detect coordinates indicating the position of the rear electrode 22 on the panel surface 12a by receiving a position signal, and then derive the distance from the previously detected coordinates indicating the position of the tip electrode 21, and derive the tilt of the pen 2 based on the result. The sensor controller 31 is configured to supply the detected coordinates, the acquired pen data, and the derived tilt to the host processor 32 each time.

[0035] The specific content of the process performed by the sensor controller 31 using the uplink signal US and the downlink signal DS differs depending on whether or not the sensor controller 31 has been paired with the pen 2. The process performed by the sensor controller 31 when it has not been paired with the pen 2 is hereinafter referred to as a "global scan," and the process performed by the sensor controller 31 when it has been paired with the pen 2 is hereinafter referred to as a "local scan." An overview of each process will be described below.

[0036] When performing a global scan, the sensor controller 31 transmits an uplink signal US to the unpaired pen 2, including a command to transmit only a position signal from the tip electrode 21. After transmitting this uplink signal US, the sensor controller 31 detects a position signal by sequentially scanning all of the sensor electrodes 30X, 30Y that constitute the sensor 30. Having thus detected the position signal, the sensor controller 31 derives the coordinates of the tip electrode 21 based on the detected position signal, and enters a state in which pairing with the pen 2 has been completed.

[0037] When performing a local scan, the sensor controller 31 transmits a position signal and a data signal from the tip electrode 21 in sequence to the paired pen 2, and then transmits an uplink signal US including a command to transmit a position signal from the rear electrode 22. The sensor controller 31 then selects a predetermined number of sensor electrodes 30X, 30Y located near the previously derived position of the tip electrode 21 from among the multiple sensor electrodes 30X, 30Y, and sequentially scans the selected sensor electrodes 30X, 30Y to first detect the position signal transmitted from the tip electrode 21. The sensor controller 31 thus detects the position signal, derives the coordinates of the tip electrode 21 based on the detected position signal, and outputs the coordinates of the pen 2 to the host processor 32.

[0038] Next, the sensor controller 31 selects one sensor electrode 30X or 30Y that is closest to the previously or currently derived position of the tip electrode 21 from among the multiple sensor electrodes 30X, 30Y, and scans the selected sensor electrode 30X or 30Y to detect the data signal transmitted from the tip electrode 21. Having detected the data signal in this manner, the sensor controller 31 acquires the pen data transmitted by the pen 2 by demodulating the detected data signal.

[0039] Finally, the sensor controller 31 selects a predetermined number of sensor electrodes 30X, 30Y located near the previously derived position of the rear electrode 22 (or the previously or currently derived position of the tip electrode 21) from among the multiple sensor electrodes 30X, 30Y, and sequentially scans the selected sensor electrodes 30X, 30Y to detect the position signal transmitted from the rear electrode 22. Having thus detected the position signal, the sensor controller 31 derives the coordinates of the rear electrode 22 based on the detected position signal. Then, based on the derived coordinates of the tip electrode 21 and the newly derived coordinates of the rear electrode 22, it derives the tilt of the pen 2 and outputs it to the host processor 32.

[0040] The host processor 32 is a processing device that executes the operation system and various applications of the computer 3 by reading and executing programs stored in a storage device (not shown). The applications executed by the host processor 32 include a drawing application. The drawing application plays a role in generating stroke data according to the coordinates, pen data (including a value indicating pen pressure), and inclination supplied from the sensor controller 31, and rendering and displaying the data on the display 10 shown in FIG. 1. The drawing application also generates digital ink data including the generated stroke data, stores the data in a storage device (not shown), and transmits the data to another computer.

[0041] We have described above the basic configurations of the pen 2 and the computer 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 sensor controller 31 to achieve both improved accuracy in detecting the coordinates of electrodes in contact with the panel surface and improved accuracy in detecting the coordinates of electrodes not in contact with the panel surface.

[0042] 3 is a process flow diagram showing the reception process of the downlink signal DS executed by the sensor controller 31 during local scanning. As shown in the figure, the sensor controller 31 performs different processes at the reception timing of the electrode in contact with the panel surface 12a and the reception timing of the electrode not in contact with the panel surface 12a. The "electrode in contact with the panel surface 12a" here is, for example, the tip electrode 21 in contact, and the "electrode not in contact with the panel surface 12a" is, for example, the rear electrode 22 or the tip electrode 21 in hover. The process related to these specific examples will be described in detail in FIG. 8 below.

[0043] 3, the sensor controller 31 first judges whether the reception timing of the electrode in contact with the panel surface 12a has arrived (step S1). If it is judged that the reception timing has arrived, the first scan is executed (step S3). On the other hand, if it is judged that the reception timing has not arrived, the sensor controller 31 further judges whether the reception timing of the electrode not in contact with the panel surface 12a has arrived (step S2). If the sensor controller 31 judges that the reception timing has arrived in step S2, it executes the second scan (step S6). If the sensor controller 31 judges that the reception timing has not arrived, it returns to step S1 and continues the process.

[0044] 4(a) is a process flow diagram showing details of the first scan executed in step S3. As shown in the figure, the sensor controller 31, which has started the first scan, performs the processes of steps S11 and S12 for each of the X direction and the Y direction (step S10). Below, the processes of steps S11 and S12 will be specifically explained focusing on the process in the X direction, but the process in the Y direction is similar.

[0045] First, the sensor controller 31 selects a predetermined number of sensor electrodes 30X included in a predetermined range (hereinafter referred to as a "first range") from the previously derived coordinates (step S11). Next, the sensor controller 31 selects at least three or more reference positions (first reference positions) at which a signal level can be detected from a position signal detected in the selected sensor electrodes 30X, and detects the signal level of the position signal at each of the selected reference positions (step S12).

[0046] Here, the reference positions are positions to be detected for the signal level of the position signal, and are arranged at equal intervals on the X-axis (on the Y-axis in the Y-direction processing). In step S12, the sensor controller 31 is configured to select three or more reference positions that are arranged consecutively among the previously derived coordinates. More specifically, the three or more reference positions are selected in order of proximity to the previously derived coordinates. Each reference position is previously associated with one or more sensor electrodes 30X, and the signal level of the position signal at each reference position detected in step S12 is the signal level of the position signal at the sensor electrode 30X if there is one sensor electrode 30X corresponding to the reference position, and is a statistically processed signal level of the position signal at those sensor electrodes 30X if there are two or more sensor electrodes 30X corresponding to the reference position. The specific content of the statistical processing may be, for example, a simple average, or a weighted addition performed by multiplying the signal level by a weight determined based on the distance from the reference position to each sensor electrode 30X. The first range is a range including all sensor electrodes 30X required to obtain the signal level of the position signal at each reference position by the processing in step S12.

[0047] 5(a), 6(a), and 7(a) are diagrams for explaining an example of the correspondence between the reference positions and the sensor electrode 30X. In these diagrams, X-coordinates K-7 to K+7 each represent a reference position. Furthermore, the X-coordinate K represents the reference position closest to the previously derived X-coordinate. Furthermore, the reference position in which the corresponding X-coordinate is surrounded by a square represents the reference position selected in step S12. Moreover, the bar graph shown above the X-axis represents the signal level of the position signal at each reference position, and the upward-sloping hatching on the bar graph represents that the signal level is actually detected in step S12.

[0048] 5(a) shows an example in which one sensor electrode 30X corresponds to each reference position. In this case, each reference position is the center position in the X direction of the corresponding sensor electrode 30X. Moreover, the signal level of the position signal at each reference position is the signal level of the position signal at the corresponding sensor electrode 30X.

[0049] 6(a) shows an example in which two sensor electrodes 30X correspond to each reference position. In this case, each reference position is the middle position in the X direction between the two corresponding sensor electrodes 30X. In addition, the signal level of the position signal at each reference position is the average value of the signal levels of the position signals at the two corresponding sensor electrodes 30X.

[0050] 7(a) shows an example in which three sensor electrodes 30X correspond to each reference position. In this case, each reference position is the center position in the X direction of the sensor electrode 30X that is located in the middle of the three corresponding sensor electrodes 30X. In addition, as the signal level of the position signal at each reference position, a value obtained by statistically processing the signal levels of the position signals at the three corresponding sensor electrodes 30X is used.

[0051] Returning to FIG. 3, after completing step S3, the sensor controller 31 derives coordinates indicating the position of the electrode in contact with the panel surface 12a based on the level of the position signal at each reference position detected in the first scan (step S4). This derivation can be performed by finding an approximation curve (quadratic function) of the detected signal level by the least squares method and deriving the coordinates of its apex. After step S4, the sensor controller 31 executes other processes (step S5) and then moves the process to step S2. The specific contents of the other processes executed in step S5 will be described later with reference to FIG. 8.

[0052] 4(b) is a process flow diagram showing details of the second scan executed in step S6. As shown in the figure, the sensor controller 31, which has started the second scan, performs the processes of steps S16 and S17 for each of the X direction and Y direction (step S15). Below, the processes of steps S16 and S17 will be specifically explained focusing on the process in the X direction, but the process in the Y direction is similar.

[0053] First, the sensor controller 31 selects a predetermined number of sensor electrodes 30X included in a predetermined range (hereinafter referred to as "second range") from the previously derived coordinates (step S16). The second range is set to a range wider than that in the first scan. Next, the sensor controller 31 selects at least three or more reference positions (second reference positions) where a signal level can be detected from a position signal detected in the selected sensor electrodes 30X, and detects the signal level of the position signal at each selected reference position (step S17). At this time, the sensor controller 31 is configured to select three or more reference positions that are discretely arranged from the multiple reference positions arranged side by side according to the previously derived coordinates. More specifically, the sensor controller 31 is configured to select a reference position closest to the previously derived coordinates and two or more reference positions arranged at a predetermined number of intervals from the reference position.

[0054] 5(b), 6(b), and 7(b) are diagrams showing a first example of the reference positions selected in step S17 when the correspondence between the reference positions and the sensor electrode 30X is as shown in FIG. 5(a), FIG. 6(a), and FIG. 7(a), respectively. The sensor controller 31 in this example is configured to select every other reference position, and as a result, a second range wider than the first range is required. Also, the width (width between both ends) of the three or more reference positions selected by the sensor controller 31 in this example is wider than the width (width between both ends) of the three or more reference positions selected by the sensor controller 31 in the corresponding first scan.

[0055] 5(c), 6(c), and 7(c) are diagrams showing a second example of the reference positions selected in step S17 when the correspondence between the reference positions and the sensor electrode 30X is as shown in FIG. 5(a), FIG. 6(a), and FIG. 7(a), respectively. The sensor controller 31 in this example is configured to select every third reference position, and as a result, a second range wider than the second range in the first example is required. In addition, the width (width between both ends) of the three or more reference positions selected by the sensor controller 31 in this example is wider than the width (width between both ends) of the three or more reference positions selected by the sensor controller 31 in the first example.

[0056] Returning to FIG. 3, after completing step S6, the sensor controller 31 derives coordinates indicating the positions of the electrodes not in contact with the panel surface 12a based on the level of the position signal at each reference position detected in the second scan (step S7). This derivation can be performed by obtaining an approximation curve (quadratic function) of the detected signal level by the least squares method and deriving the coordinates of its apex, as in step S4. After step S7, the sensor controller 31 executes other processes (step S8) and then moves the process to step S1. The specific contents of the other processes executed in step S8 will also be described later with reference to FIG. 8.

[0057] Fig. 8 is a process flow diagram showing a more specific example of the reception process shown in Fig. 3. Hereinafter, with reference to the same figure, the reception process of the downlink signal DS executed by the sensor controller 31 during local scan will be described along with a more specific example.

[0058] First, the sensor controller 31 judges whether the reception timing of the tip electrode 21 has arrived (step S20). If it is judged that the reception timing has arrived, the sensor controller 31 next judges whether the pen 2 is in hover (step S21). Specifically, if the value of the writing pressure included in the pen data received from the pen 2 in the previous local scan was 0, it is judged that the pen 2 is in hover, and otherwise it is judged that the pen 2 is not in hover (i.e., in contact).

[0059] Here, the pen 2 may place contact / hover information indicating whether or not it is hovering in the pen data, and in that case, the sensor controller 31 may determine whether or not the pen 2 is hovering based on this contact / hover information. Also, the sensor controller 31 may determine whether or not the pen 2 is hovering based on data (pen pressure value or contact / hover information) received from the pen 2 via short-range wireless communication such as Bluetooth (registered trademark).

[0060] If the sensor controller 31 determines in step S21 that the sensor is not hovering, it executes the process of step S22. Step S22 is a process corresponding to step S3 in FIG. 3, in which the sensor controller 31 executes a first scan and obtains the signal level of the position signal at each reference position as a result. On the other hand, if the sensor controller 31 determines in step S21 that the sensor is hovering, it executes step S23. Step S23 is a process corresponding to step S6 in FIG. 3, in which the sensor controller 31 executes a second scan and obtains the signal level of the position signal at each reference position as a result.

[0061] After completing step S22 or step S23, the sensor controller 31 executes the processes of steps S24 to S26. Step S24 corresponds to step S4 or step S7 in Fig. 3, and the sensor controller 31 derives coordinates indicating the position of the tip electrode 21 based on the signal level obtained in step S22 or step S23. Steps S25 and S26 correspond to step S5 or step S8 in Fig. 3, and the sensor controller 31 receives the pen data transmitted by the pen 2 by receiving the above-mentioned data signal (step S25), and outputs it to the host processor 32 together with the coordinates derived in step S24 (step S26).

[0062] If the sensor controller 31 determines in step S20 that the signal has not arrived, it determines whether the reception timing of the rear end electrode 22 has arrived (step S30). If the sensor controller 31 determines that the signal has not arrived, it returns to step S20 and continues processing. On the other hand, if the sensor controller 31 determines that the signal has arrived, it determines whether the pen 2 is in hover (step S31). The specific method of this determination may be the same as that in step S21. If the sensor controller 31 determines that the signal is in hover in step S31, it returns to step S20 and continues processing.

[0063] On the other hand, if the sensor controller 31 determines in step S31 that the object is not hovering, it executes the processes of steps S32 to S35. Note that step S31 may not be executed, and in that case, the sensor controller 31 may always execute the processes of steps S32 to S35 in response to the determination in step S30 that the object has not arrived.

[0064] Step S32 corresponds to step S6 in Fig. 3, in which the sensor controller 31 executes a second scan and obtains the signal level of the position signal at each reference position as a result. Step S33 corresponds to step S7 in Fig. 3, in which the sensor controller 31 derives coordinates indicating the position of the rear electrode 22 based on the signal level obtained in step S32. Steps S34 and S35 correspond to step S8 in Fig. 3, in which the sensor controller 31 derives the tilt of the pen 2 based on the coordinates of the tip electrode 21 derived in step S24 and the coordinates of the rear electrode 22 derived in step S33 (step S34), and outputs the tilt to the host processor 32 (step S35).

[0065] As described above, according to the touch pad 12 of the present embodiment, by making the pitch P of the sensor electrodes 30X, 30Y smaller than the conventional pitch, it is possible to perform coordinate detection of the tip electrode 21 in contact with high accuracy, while scanning the position signal transmitted from the rear end electrode 22 or the tip electrode 21 in hover over a wider range than the position signal transmitted from the tip electrode 21 in contact. Therefore, it is possible to capture the position signal from the rear end electrode 22 or the tip electrode 21 in hover, which tends to spread on the panel surface 12a, over a wider range, and therefore it is possible to improve both the accuracy of coordinate detection of the tip electrode 21 in contact and the accuracy of coordinate detection of the rear end electrode 22 or the tip electrode 21 in hover.

[0066] The effects achieved by the present invention will be described in detail below with reference to FIGS.

[0067] 9(a) to 9(c), 10(a) to 10(c), and 11(a) to 11(c) are diagrams showing measurement results of the signal level of the position signal transmitted from the rear electrode 22 at each reference position. In these diagrams, the vertical axis represents the signal level. In addition, in FIG. 9(a) to FIG. 9(c), the horizontal axis represents the reference position in the X direction, and in FIG. 10(a) to FIG. 10(c) and FIG. 11(a) to FIG. 11(c), the horizontal axis represents the reference position in the Y direction. In addition, FIG. 9(a) to FIG. 9(c) and FIG. 10(a) to FIG. 10(c) show a case where the inclination θ of the pen 2 (the angle between the pen axis of the pen 2 and the normal line to the panel surface 12a) is 0° (i.e., the pen 2 stands perpendicular to the panel surface 12a), and FIG. 11(a) to FIG. 11(c) show a case where θ is 30°. Furthermore, Figures 9(a), 10(a), and 11(a) show the signal levels at all reference positions, Figures 9(b), 10(b), and 11(b) show the signal levels at every other reference position selected, and Figures 9(c), 10(c), and 11(c) show the signal levels at every third reference position selected.

[0068] 9(a) and 10(a), when θ=0°, the upper end of the curve represented by the signal levels of each reference position is flat, so that even if three reference positions are selected from the center and approximated by the least squares method, it is not possible to correctly derive the coordinates of the rear electrode 22. The reasons why the upper end of the curve is flat as in Fig. 9(a) and Fig. 10(a) include the fact that the rear electrode 22 is not in contact with the panel surface 12a, and the fact that the tip electrode 21 exists between the rear electrode 22 and the panel surface 12a.

[0069] 9(b) and 10(b), it can be seen that thinning out the reference positions by half makes the flat part at the top of the curve a little smaller. However, in this state, the flat part is still not sufficiently reduced, and it is not necessarily possible to correctly derive the coordinates of the rear electrode 22.

[0070] Next, referring to Figures 9(c) and 10(c), it can be seen that by thinning out the reference positions to 1 / 3, the flat portion at the top end of the curve becomes even smaller. In this state, it can be said that the flat portion has been sufficiently reduced, and it becomes possible to correctly derive the coordinates of the rear electrode 22. Therefore, when θ=0°, it can be said that it becomes possible to correctly derive the coordinates of the rear electrode 22 by configuring the sensor controller 31 to select every third reference position, as in the examples shown in Figures 5(c), 6(c), and 7(c).

[0071] On the other hand, referring to Figures 11(a) to 11(c), when θ=30°, even in the state of Figure 11(a) where the reference positions are not thinned out, the upper end of the curve represented by the signal levels of each reference position is sufficiently convex upward, so it is understood that the coordinates of the rear electrode 22 can be correctly derived. Also, as is clear from Figures 11(b) and 11(c), it is understood that even if the reference positions are thinned out, the coordinates of the rear electrode 22 can still be correctly derived. Note that Figures 11(a) to 11(c) only show the measurement results at each reference position in the Y direction, but the same applies to the measurement results at each reference position in the X direction.

[0072] As can be seen from the measurement results in Figures 9(a) to 9(c), 10(a) to 10(c), and 11(a) to 11(c), the coordinate detection accuracy of the electrode not in contact with the panel surface tends to deteriorate as the inclination θ becomes smaller. Therefore, it can be said that the effect of improving the coordinate detection accuracy according to the present invention is more remarkable as the inclination θ becomes smaller. Although not shown, for example, in the case of θ=10°, which is between θ=0° and θ=30° described above, thinning out the reference positions by half makes it possible to derive the coordinates of the rear electrode 22 sufficiently accurately.

[0073] Fig. 12(a) and Fig. 12(b) are diagrams showing the trajectory of the position of the rear electrode 22 when the tip of the pen 2 is slid on the panel surface 12a while maintaining θ=0°. Fig. 12(a) shows a comparative example to which the present invention is not applied, and Fig. 12(b) shows an embodiment to which the present invention is applied. However, in the embodiment of Fig. 12(b), the sensor controller 31 is configured to select every third reference position in the second scan.

[0074] As can be seen from Fig. 12(a), in the comparative example to which the present invention is not applied, large jitter appears in the trajectory of the position of the rear electrode 22. This indicates that the upper end of the curve represented by the signal levels of each reference position becomes flat, as in the example shown in Fig. 9(a), and the position of the apex of the approximation curve (quadratic function) obtained by the least squares method becomes unstable.

[0075] In contrast, in the embodiment to which the present invention is applied, almost no jitter is observed, as can be seen from Fig. 12(b). From this result, it can be seen that according to the present invention, it is possible to improve the detection accuracy of the coordinates detected based on the position signal transmitted from the rear electrode 22.

[0076] 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.

[0077] Fig. 13 is a process flow diagram showing a receiving process of a downlink signal DS executed by the sensor controller 31 according to a modification of the above embodiment during a local scan. The sensor controller 31 according to this modification is configured to select whether to perform the first scan or the second scan for each electrode of the pen 2 based on the detection result of the previous signal level. This will be described in detail below with reference to Fig. 13.

[0078] First, the sensor controller 31 according to this modification sets a transition flag, which is a Boolean variable provided for each electrode of the pen 2, to false (step S40). Then, the sensor controller 31 executes the processes of steps S42 to S51 for each electrode of the pen 2 (step S41).

[0079] Specifically, the sensor controller 31 first judges whether the reception timing of the electrode of interest has arrived (step S42). If it is judged that the reception timing has not arrived, the process proceeds to the next electrode, whereas if it is judged that the reception timing has arrived, the value of the transition flag of the electrode of interest is judged (step S43). If it is judged to be False, the first scan is executed (step S44), and if it is judged to be True, the second scan is executed (step S47). The specific contents of the first scan and the second scan are as described with reference to FIG. 4.

[0080] After executing the first scan in step S44, the sensor controller 31 determines whether the difference between the maximum (peak level) of the detected signal levels and the other signal levels is equal to or less than a predetermined value (step S45). Only when it is determined that the difference is equal to or less than the predetermined value, the sensor controller 31 sets the transition flag of the target electrode to true, and proceeds to step S48.

[0081] The sensor controller 31 that has performed the second scan in step S47, or that has completed the processes of steps S45 and S46, derives coordinates indicating the position of the target electrode based on the signal level detected in step S44 or step S47 (step S48). A specific method of this derivation may be similar to steps S4 and S7 in FIG. 3. After step S48, the sensor controller 31 executes other processes (step S49). The specific contents of the other processes vary depending on the document of the target electrode, but are, for example, the processes of steps S25 and S26 or steps S34 and S35 shown in FIG. 8.

[0082] Next, the sensor controller 31 judges again the value of the transition flag of the electrode of interest (step S50). As a result, if it is judged to be False, the process proceeds to the next electrode, whereas if it is judged to be True, the process proceeds to judge whether a factor for returning the transition flag of the electrode of interest to False has occurred (step S51). For example, if the electrode of interest is the tip electrode 21, this factor may be that the value of the writing pressure received from the pen 2 has become greater than 0 (i.e., the tip electrode 21 has entered contact), and if the electrode of interest is the rear electrode 22, the derived inclination θ of the pen 2 has become equal to or greater than a predetermined value. Only when it is judged in step S51 that a return factor has occurred, the sensor controller 31 sets the transition flag of the electrode of interest to False and proceeds to the next electrode.

[0083] As described above, according to touchpad 12 of this modification, it is possible to change the scanning method from the first scan to the second scan for electrodes where the difference between the peak level and other signal levels is equal to or less than a predetermined value. Therefore, it is possible to capture position signals transmitted from electrodes where the upper ends of the curves represented by the signal levels of the reference positions are flat over a wider range, so that touchpad 12 of this modification also makes it possible to improve both the accuracy of detecting the coordinates of electrodes in contact with panel surface 12a and the accuracy of detecting the coordinates of electrodes not in contact with panel surface 12a.

[0084] In the above modification, the scanning method of an electrode in which the difference between the peak level and other signal levels is equal to or less than a predetermined value is changed from the first scan to the second scan, but the scanning method of a specific electrode may be changed from the first scan to the second scan by other methods. For example, when the value of the tilt θ detected previously is equal to or less than a predetermined value, the scanning method of the rear electrode 22 may be changed from the first scan to the second scan. [Explanation of symbols]

[0085] 1 Electronic equipment 2 Pen 3. Computer 10. Display 11 Keyboard 12 Touchpad 12a Panel surface 20 cores 21 Tip electrode 22 Back end electrode 23 Pen pressure detection sensor 24 Circuit section 25 Power supply 30 Sensors 30X, 30Y Sensor electrodes 31 Sensor Controller 32 Host Processor DS Downlink Signal Pitch US uplink signal

Claims

1. determining whether the pen is in contact based on data received from the pen via near field communication; When it is determined that the pen is in contact, a first scan is performed to select a plurality of first reference positions that are equally spaced from a plurality of reference positions that are equally spaced, and to detect a signal level of a position signal at each of the selected plurality of first reference positions; when it is determined that the pen is not in contact, a second scan is performed to select a plurality of second reference positions, which are equally spaced and spaced wider than the plurality of first reference positions, from among the plurality of reference positions, and to detect a signal level of a position signal at each of the selected plurality of second reference positions; Sensor controller.

2. The plurality of first reference positions are the plurality of reference positions that are consecutively arranged. The sensor controller of claim 1 .

3. deriving coordinates indicative of a position of the pen based on the signal level obtained by the first scan or the second scan; The sensor controller of claim 1 .

4. selecting the plurality of first reference positions or the plurality of second reference positions based on previously derived coordinates; The sensor controller according to claim 3 .

5. The data is a value of the writing pressure applied to the tip of the pen. The sensor controller of claim 1 .

6. connected to each of a plurality of sensor electrodes arranged in parallel at a constant pitch; the plurality of reference positions each correspond to one or more predetermined number of the sensor electrodes; a signal level of the position signal at the reference position is detected based on signal levels of the position signals at the predetermined number of sensor electrodes corresponding to the reference position; The sensor controller of claim 1 .

7. determining whether the pen is in contact based on data received from the pen via short-range wireless communication; a step of selecting a plurality of evenly spaced first reference positions from a plurality of evenly spaced reference positions in response to determining that the pen is in contact with the touch panel, and executing a first scan to detect a signal level of a position signal at each of the selected plurality of first reference positions; a step of selecting a plurality of second reference positions, which are equally spaced apart from the plurality of reference positions and are spaced apart more widely than the plurality of first reference positions, from the plurality of reference positions in response to determining that the pen is not in contact with the touch panel, and executing a second scan to detect a signal level of a position signal at each of the selected plurality of second reference positions; The method includes:

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