Sensor controller, method, and position detector

Abstract

To provide a sensor controller and a method which can suppress a pen detection signal from interfering with a pixel driving signal.SOLUTION: A sensor controller according to the present invention is connected to an EMR sensor on a display. The sensor controller conducts an operation to detect an electromagnetic induction pen with the EMR sensor in synchronization with a touch detection operation to detect a touch that a passive pointer made on the panel surface of the display, and conducts an operation of detecting the electromagnetic induction pen with the EMR sensor in synchronization with pixel drive of the display in a case where the sensor controller detected the electromagnetic induction pen.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sensor controller, a method, and a position detection device, and particularly to a sensor controller connected to a sensor of an electromagnetic induction method (EMR method), a method executed by the sensor controller, and a position detection device including the sensor controller.

Background Art

[0002] There is known a position detection device having a configuration in which an EMR sensor for detecting an electromagnetic induction pen in pen input by an electromagnetic induction method and a touch sensor for detecting a passive pointer in touch input by a passive pointer such as a finger by a capacitance method are superimposed on a display for displaying an image or the like. Patent Document 1 discloses an example of such a position detection device.

[0003] Further, Patent Document 2 discloses a position detection device having an EMR sensor and a touch sensor. When an electromagnetic induction pen is detected by the EMR sensor, this position detection device is configured to stop the position detection of the passive pointer by the touch sensor and perform only the position detection of the pen by the EMR sensor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, among conventional position detection devices in which an EMR sensor, a touch sensor, and a display are superimposed, the detection operation of a passive pointer (hereinafter referred to as "touch detection operation") performed using the touch sensor is executed in synchronization with the pixel driving of the display (hereinafter simply referred to as "pixel driving"), and the operation for detecting an electromagnetic induction pen using the EMR sensor (hereinafter referred to as "pen detection operation") is executed in synchronization with the touch detection operation. As a result, there is a type in which the pen detection operation is indirectly synchronized with the pixel driving.

[0006] In such a position detection device, when the position detection of the passive pointer as described in Patent Document 2 stops, the pen detection operation cannot be synchronized with the touch detection operation. Then, since it becomes impossible to synchronize with the pixel driving as well, there is a problem that interference occurs between the signal used for the pen detection operation (including a current signal for generating an alternating magnetic field and a current signal generated by the alternating magnetic field sent out by the electromagnetic induction pen) and the pixel driving signal (including a gate signal and a source signal) used for the pixel driving of the display.

[0007] Here, among conventional position detection devices, there are some that generate a synchronization signal synchronized with the pixel driving and perform the touch detection operation in synchronization with this synchronization signal, thereby synchronizing the touch detection operation with the pixel driving. And furthermore, there are some in which the generation of this synchronization signal does not stop even when the touch detection operation is stopped due to the detection of the electromagnetic induction pen. In such a position detection device, if the pen detection operation is performed in synchronization with the above synchronization signal even during the stop of the touch detection operation, it is possible to perform the pen detection operation in synchronization with the touch detection operation (which is actually not performed).

[0008] However, the reason for executing the pen detection operation in synchronization with the touch detection operation in the conventional position detection device in the first place is to prevent the pen detection operation and the touch detection operation from interfering with each other as noise. Therefore, during the stop of the touch detection operation, there is no need to synchronize with the touch detection operation in the first place. If so, it is preferable to directly synchronize the pen detection operation with the pixel driving. By doing so, the effect of suppressing the interference between the signal used for the pen detection operation and the pixel driving signal used for the pixel driving of the display can be maximized. Nevertheless, according to the above method, even during the stop of the touch detection operation, the pen detection operation is performed in synchronization with the touch detection operation. Therefore, the synchronization between the pen detection operation and the pixel driving becomes indirect, and the interference suppression effect that should originally be obtained cannot be sufficiently obtained.

[0009] Therefore, one of the objects of the present invention is to provide a sensor controller, a method, and a position detection device that can surely suppress the interference between the signal used for the pen detection operation and the pixel driving signal used for the pixel driving of the display.

Means for Solving the Problems

[0010] The sensor controller according to the present invention is a sensor controller connected to an EMR sensor disposed overlapping a display, and performs an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation for detecting a touch by a passive pointer within a panel surface of the display. When the electromagnetic induction pen is detected, it is a sensor controller that performs an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with the pixel driving of the display.

[0011] The method according to the present invention is a method executed by a sensor controller connected to an EMR sensor disposed overlapping a display, the method including: performing an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation for detecting a touch by a passive pointer within a panel surface of the display; and performing an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with pixel driving of the display when the electromagnetic induction pen is detected.

[0012] A position detection device according to the present invention includes: a display; an EMR sensor and a touch sensor disposed overlapping the display; and a sensor controller connected to each of the EMR sensor and the touch sensor, wherein the sensor controller performs an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation performed using the touch sensor for detecting a touch by a passive pointer within a panel surface of the display, and performs an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with pixel driving of the display when the electromagnetic induction pen is detected.

Advantages of the Invention

[0013] According to the present invention, when a touch detection operation is performed, a pen detection operation is performed in synchronization with the touch detection operation, and when the touch detection operation is not performed, the pen detection operation is performed in synchronization with pixel driving of the display. Therefore, it is possible to surely prevent signals used for the pen detection operation and signals used for pixel driving of the display from interfering with each other.

Brief Description of the Drawings

[0014]

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Embodiments for Carrying Out the Invention

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

[0016] FIG. 1 is a diagram showing the configuration of a position detection system 1 according to a first embodiment of the present invention. As shown in the figure, the position detection system 1 is configured to include an electromagnetic induction pen 2 and a position detection device 3. Among these, the electromagnetic induction pen 2 is a pen corresponding to position detection by the EMR method, and is configured to have a resonance circuit including a coil and a capacitor inside.

[0017] The position detection device 3 is a computer corresponding to pen input by the EMR method and touch input by the capacitance method, and is configured to include a sensor controller 30, a host processor 31, a touch sensor 41, a display 42, and an EMR sensor 43. In a typical example, the position detection device 3 is a tablet terminal or a notebook personal computer corresponding to pen input and touch input.

[0018] The touch sensor 41, the display 42, and the EMR sensor 43 are arranged in this order and stacked from the panel surface 3a side of the position detection device 3. As a result, the panel surface 3a is the display surface of the display 42 and also serves as a touch surface for the user to perform pen input and touch input.

[0019] The touch sensor 41 is a sensor used to detect a passive pointer by the capacitance method, and includes a plurality of first linear electrodes extending in a first direction in the panel surface 3a and juxtaposed at equal intervals in a second direction orthogonal to the first direction in the panel surface 3a, and a plurality of second linear electrodes extending in the second direction and juxtaposed at equal intervals in the first direction. The plurality of first linear electrodes and the plurality of second linear electrodes are each connected to a touch detection circuit 22 (described later) in the sensor controller 30.

[0020] The EMR sensor 43 is a sensor used to detect the electromagnetic induction pen 2, and includes a plurality of first loop coils each extending in a first direction and arranged side by side in a second direction, and a plurality of second loop coils each extending in the second direction and arranged side by side in the first direction. The plurality of first loop coils and the plurality of second loop coils are each connected to a pen detection circuit 23 (described later) in the sensor controller 30.

[0021] The sensor controller 30 is an integrated circuit having a function of deriving the position of a passive pointer in the panel surface 3a using the touch sensor 41 and a function of deriving the position of the electromagnetic induction pen 2 in the panel surface 3a using the EMR sensor 43. The sensor controller 30 is also configured to have a function of receiving data transmitted by the electromagnetic induction pen 2. The position derived by the sensor controller 30 and the received data are sequentially supplied to the host processor 31.

[0022] The host processor 31 is the central processing unit of the position detection device 3 and is connected to the display 42 and the sensor controller 30. The host processor 31 serves to execute the operating system and various applications of the position detection device 3 by executing a program read from a memory (not shown). The processes executed by the host processor 31 according to the program include a process of generating a video signal and supplying it to the display 42, and various processes performed using the position and data supplied from the sensor controller 30. The various processes performed using the position and data include, for example, moving the cursor displayed by the display 42 on the panel surface 3a, and generating stroke data indicating the trajectory of the electromagnetic induction pen 2 in the panel surface 3a. Regarding the stroke data among these, the host processor 31 also performs processes such as rendering and displaying the generated stroke data, generating and recording digital ink including the generated stroke data, and transmitting the generated digital ink to an external device according to a user's instruction.

[0023] The display 42 is a display device having a plurality of pixels arranged in a matrix and a drive circuit for driving these pixels individually. In a specific example, the display 42 can be configured by a liquid crystal display, an organic EL display, an electronic paper, or the like. The drive circuit of the display 42 plays a role of displaying a video signal on the panel surface 3a by driving each pixel according to the video signal supplied from the host processor 31.

[0024] FIG. 2 is a diagram showing the internal configuration of the sensor controller 30. As shown in the figure, the sensor controller 30 includes a touch detection operation control circuit 20, a pen detection operation control circuit 21, a pen detection circuit 23, and a touch detection circuit 22. Further, FIG. 3 is a time chart showing each signal according to the present embodiment, as well as the operation and operation mode of the sensor controller 30. Hereinafter, the configuration and operation of the sensor controller 30 will be described in detail with reference to these figures.

[0025] The touch detection circuit 22 is a circuit that plays a role of executing the touch detection operation described above using the touch sensor 41. Specifically, the touch detection circuit 22 transmits different touch detection signals to each of a plurality of first linear electrodes in the touch sensor 41 and receives them at each of a plurality of second linear electrodes. Then, based on the reception result, it is configured to derive the position of the passive pointer in the panel surface 3a.

[0026] The touch detection operation control circuit 20 is a circuit that controls the timing at which the touch detection circuit 22 performs the above operation. Specifically, the touch detection operation control circuit 20 generates a touch detection operation synchronization signal TP_VSYNC indicating the operation timing of the touch detection operation and is configured to supply it to the touch detection circuit 22. As shown in FIG. 3, the touch detection circuit 22 is configured to perform one touch detection operation (indicated as "TS" in FIG. 3) each time the touch detection operation synchronization signal TP_VSYNC is activated.

[0027] Here, the host processor 31 is configured to generate a vertical synchronization signal DISP_VSYNC indicating the start timing of a frame period F, which is a period during which one-screen display is executed, and a horizontal synchronization signal DISP_HSYNC indicating the switching timing of video lines, and supply them to the display 42 together with a video signal. The drive circuit of the display 42 described above is configured to drive a plurality of pixels at a timing according to these signals. As a result, the image displayed on the panel surface 3a by the display 42 is updated at the frame period F.

[0028] As shown by the dashed arrow in FIG. 3, the touch detection operation control circuit 20 is configured to activate a synchronization signal TP_VSYNC for touch detection operation in synchronization with the vertical synchronization signal DISP_VSYNC generated by the host processor 31. As a result, the touch detection circuit 22 performs a touch detection operation in synchronization with the pixel driving of the display 42.

[0029] The pen detection circuit 23 is a circuit that plays a role of executing the above-described pen detection operation using the EMR sensor 43. Specifically, the pen detection circuit 23 generates an alternating magnetic field on the panel surface 3a by supplying an alternating current to one of a plurality of first loop coils in the EMR sensor 43 for a predetermined period. When the coil constituting the resonance circuit of the electromagnetic induction pen 2 enters this alternating magnetic field, an electromotive force is generated at both ends of the coil, and the capacitor constituting the resonance circuit together with the coil is charged. When the alternating magnetic field on the panel surface 3a disappears due to the pen detection circuit 23 stopping the supply of the alternating current, an alternating current flows through the coil of the resonance circuit by the power stored in the capacitor, and the alternating magnetic field is transmitted. The pen detection circuit 23 detects an alternating current (pen signal) generated by this alternating magnetic field in each of the plurality of second loop coils and acquires the detection intensity. The pen detection circuit 23 is configured to execute the above processing for each of the plurality of first loop coils, acquire the distribution of the detection intensity in the panel surface 3a, and derive the position of the electromagnetic induction pen 2 in the panel surface 3a based on the result.

[0030] The pen detection circuit 23 is configured to execute the above-described pen detection operation by any one of global scan, idle scan, and sector scan in accordance with the control of a pen detection operation control circuit 21 described later.

[0031] The global scan is a pen detection operation executed using all the first loop coils and all the second loop coils in the EMR sensor 43. In FIG. 3, the global scan is denoted as "GS". According to the global scan, it becomes possible to detect the electromagnetic induction pen 2 over the entire panel surface 3a, while it takes a relatively long time to execute one pen detection operation.

[0032] The idle scan is a pen detection operation executed when the host processor 31 is in an idle state, and is the same as the global scan in that it is executed using all the first loop coils and all the second loop coils in the EMR sensor 43, but is different from the global scan in that the pen detection operation is executed at a lower frequency than the global scan. According to the idle scan, the electromagnetic induction pen 2 can be detected only at a lower frequency than the global scan, but it becomes possible to reduce the power consumption due to the pen detection operation. When the host processor 31 in the idle state operates at a lower clock than the normal state, the idle scan is executed at a lower clock (i.e., over a longer time) than the global scan.

[0033] Sector scan is a pen detection operation for updating the position of the detected electromagnetic induction pen 2 when the electromagnetic induction pen 2 has already been detected, and is executed using only a predetermined number of first loop coils and second loop coils in the vicinity of the previously derived position among the plurality of first loop coils and the plurality of second loop coils in the EMR sensor 43. In FIG. 3, the sector scan is denoted as "SS". According to the sector scan, although the electromagnetic induction pen 2 cannot be detected throughout the panel surface 3a, it is possible to complete one pen detection operation in a relatively short time.

[0034] In the following description, the operation modes of the pen detection circuit 23 that executes the global scan, the idle scan, and the sector scan are referred to as the global scan mode, the idle scan mode, and the sector scan mode, respectively.

[0035] The pen detection operation control circuit 21 is a circuit that controls the timing at which the pen detection circuit 23 executes the pen detection operation and also controls the operation mode of the pen detection circuit 23. Specifically described, the pen detection operation control circuit 21 is configured to selectively generate either the pen detection operation synchronization signal INT_VS_EMR_G indicating the operation timing of the pen detection operation in global scan or the pen detection operation synchronization signal INT_VS_EMR_S indicating the operation timing of the pen detection operation in sector scan, and supply it to the pen detection circuit 23. As shown in FIG. 3, the pen detection circuit 23 is configured to perform one global scan each time the pen detection operation synchronization signal INT_VS_EMR_G is activated, and perform one sector scan each time the pen detection operation synchronization signal INT_VS_EMR_S is activated. The pen detection operation control circuit 21 operates the pen detection circuit 23 in the global scan mode by activating the pen detection operation synchronization signal INT_VS_EMR_G at a relatively high frequency, operates the pen detection circuit 23 in the idle scan mode by activating the pen detection operation synchronization signal INT_VS_EMR_G at a relatively low frequency, and operates the pen detection circuit 23 in the sector scan mode by activating the pen detection operation synchronization signal INT_VS_EMR_S.

[0036] Here, the host processor 31 stores a status flag IDLE indicating whether it is in an idle state. The pen detection operation control circuit 21 determines whether the host processor 31 is in an idle state by referring to this status flag IDLE. When it is determined that the host processor 31 is in an idle state, the pen detection operation control circuit 21 operates the pen detection circuit 23 in the idle scan mode by activating the pen detection operation synchronization signal INT_VS_EMR_G at a relatively low frequency. On the other hand, when it is determined that the host processor 31 is not in an idle state, the pen detection operation control circuit 21 operates the pen detection circuit 23 in the global scan mode by activating the pen detection operation synchronization signal INT_VS_EMR_G at a relatively high frequency.

[0037] As shown by the dashed arrows in FIG. 3, the pen detection operation control circuit 21 activates the synchronization signal INT_VS_EMR_G for pen detection operation in synchronization with the touch detection operation synchronization signal TP_VSYNC generated by the touch detection operation control circuit 20 as a general rule. On the other hand, after the electromagnetic induction pen 2 is detected, the pen detection operation control circuit 21 activates the synchronization signals INT_VS_EMR_G and INT_VS_EMR_S for pen detection operation in synchronization with the vertical synchronization signal DISP_VSYNC generated by the host processor 31. Note that since the electromagnetic induction pen 2 is always detected at the timing when the synchronization signal INT_VS_EMR_S for pen detection operation is activated, the synchronization signal INT_VS_EMR_S for pen detection operation is not activated in synchronization with the touch detection operation synchronization signal TP_VSYNC. Thus, before detecting the electromagnetic induction pen 2, the pen detection circuit 23 performs a pen detection operation (specifically, global scan or idle scan) in synchronization with the touch detection operation. When the electromagnetic induction pen 2 is detected by this pen detection operation, the pen detection circuit 23 performs a pen detection operation (specifically, global scan or sector scan) in synchronization with the pixel driving of the display 42.

[0038] The reason why the pen detection operation control circuit 21 performs such an operation is that in the present embodiment, when the electromagnetic induction pen 2 is detected by the pen detection circuit 23, the touch detection operation control circuit 20 stops generating the touch detection operation synchronization signal TP_VSYNC. This stop is performed to prevent the touch detection operation from being performed while pen input is being performed by the electromagnetic induction pen 2 and noise from being mixed into the stroke data as a result. The pen detection circuit 23 stores a status flag PFLG indicating whether or not the electromagnetic induction pen 2 is being detected. The touch detection operation control circuit 20 is configured to determine whether or not the electromagnetic induction pen 2 is being detected by referring to this status flag PFLG and to determine whether or not to stop generating the touch detection operation synchronization signal TP_VSYNC according to the result.

[0039] FIG. 3 shows an example in which the electromagnetic induction pen 2 is detected at time t1 when the pen detection circuit 23 is operating in the idle scan mode. In this case, the pen detection operation control circuit 21 once operates the pen detection circuit 23 in the global scan mode immediately after the electromagnetic induction pen 2 is detected. That is, the pen detection operation control circuit 21 activates the synchronization signal INT_VS_EMR_G for pen detection operation in synchronization with the vertical synchronization signal DISP_VSYNC. As described above, the idle scan may be executed at a lower clock than the global scan. As a result, the position of the electromagnetic induction pen 2 detected by the idle scan may be less accurate than the position of the electromagnetic induction pen 2 detected by the global scan. However, by once causing the pen detection circuit 23 to perform a global scan in this way, it becomes possible to detect the position of the electromagnetic induction pen 2 with the accuracy of a normal global scan. After the position of the electromagnetic induction pen 2 is detected by the global scan, the pen detection operation control circuit 21 activates the synchronization signal INT_VS_EMR_S for pen detection operation in synchronization with the vertical synchronization signal DISP_VSYNC. Thereby, the pen detection circuit 23 can update the position of the electromagnetic induction pen 2.

[0040] FIG. 4 is a flowchart showing the processing of the touch detection operation control circuit 20, and FIGS. 5 to 7 are flowcharts showing the processing of the pen detection operation control circuit 21. Hereinafter, the operation of the sensor controller 30 will be described in more detail again with reference to these figures.

[0041] First, referring to FIG. 4, the touch detection operation control circuit 20 determines whether or not the pen detection circuit 23 is detecting the electromagnetic induction pen 2 by referring to the status flag PFLG stored in the pen detection circuit 23 (step S1). If it is determined in this determination that detection is in progress, the touch detection operation control circuit 20 continues the determination process of step S1. In this case, the synchronization signal TP_VSYNC for touch detection operation is not activated, and the touch detection operation by the touch detection circuit 22 is not performed.

[0042] On the other hand, when it is determined in step S1 that detection is not in progress, the touch detection operation control circuit 20 performs a process of activating the synchronization signal TP_VSYNC for touch detection twice in synchronization with the vertical synchronization signal DISP_VSYNC (steps S2 to S5).

[0043] Specifically, the touch detection operation control circuit 20 determines whether the vertical synchronization signal DISP_VSYNC is activated (step S2). When it is determined that it is not activated, the process of step S2 is repeated. On the other hand, when it is determined that it is activated, the synchronization signal TP_VSYNC for touch detection is activated (step S3). Then, it is determined whether a predetermined time has elapsed (step S4). When it is determined that the predetermined time has elapsed, the synchronization signal TP_VSYNC for touch detection is activated again (step S5).

[0044] After step S5 is completed, the touch detection operation control circuit 20 returns to step S1 and repeats the above process. As a result, on the condition that the pen detection circuit 23 is not detecting the electromagnetic induction pen 2, the touch detection operation is executed twice for each frame period F shown in FIG. 3.

[0045] Next, referring to FIG. 5, the pen detection operation control circuit 21 determines whether the host processor 31 is in the idle state or the normal state by referring to the status flag IDLE stored in the host processor 31 (step S10). When it is determined in this determination that it is in the normal state, the pen detection operation control circuit 21 moves to step S20 shown in FIG. 6 and continues the process.

[0046] On the other hand, the pen detection operation control circuit 21 that determines in step S10 that it is in the idle state operates the pen detection circuit 23 in the idle scan mode. Therefore, every time the synchronization signal TP_VSYNC for touch detection is activated three times, the synchronization signal INT_VS_EMR_G for pen detection is activated in synchronization with the synchronization signal TP_VSYNC for touch detection at a ratio of once (steps S11 to S15).

[0047] Specifically, the pen detection operation control circuit 21 first sets 0 to a variable N which is a counter (step S11), and repeatedly performs a process of determining whether or not a synchronization signal TP_VSYNC for touch detection operation is activated until the synchronization signal TP_VSYNC for touch detection operation is activated (step S12). When it is determined in this determination that the synchronization signal TP_VSYNC for touch detection operation is activated, the pen detection operation control circuit 21 determines whether or not the variable N is 2 or more (step S13). If it is 2 or more, the synchronization signal INT_VS_EMR_G for pen detection operation is activated (step S15). On the other hand, if it is not 2 or more, after adding 1 to N (step S14), the process returns to step S12. When the synchronization signal INT_VS_EMR_G for pen detection operation is activated in step S15, the pen detection circuit 23 executes a global scan once.

[0048] The pen detection operation control circuit 21 that activated the synchronization signal INT_VS_EMR_G for pen detection operation in step S15 determines whether or not the electromagnetic induction pen 2 is detected (step S16). The result of this determination is affirmative when the pen detection circuit 23 detects the electromagnetic induction pen 2 by the global scan executed according to the synchronization signal INT_VS_EMR_G activated in step S15, and negative otherwise.

[0049] When a negative result is obtained in step S16, the pen detection operation control circuit 21 determines again whether the host processor 31 is in an idle state or a normal state by referring to the status flag IDLE stored in the host processor 31 again (step S17). When an affirmative result is obtained in step S16, and when the pen detection operation control circuit 21 obtains a determination result of the normal state in step S17, the process proceeds to step S20 shown in FIG. 6 and continues the process. On the other hand, the pen detection operation control circuit 21 that obtains a determination result of the idle state in step S17 returns to step S11 and continues the process.

[0050] Next, referring to FIG. 6, the pen detection operation control circuit 21 that has transitioned to step S20 performs a process of activating a synchronization signal INT_VS_EMR_G for pen detection in synchronization with the vertical synchronization signal DISP_VSYNC each time the vertical synchronization signal DISP_VSYNC is activated in order to operate the pen detection circuit 23 in the global scan mode (steps S20 to S23).

[0051] Specifically, the pen detection operation control circuit 21 repeatedly performs a process of determining whether or not the vertical synchronization signal DISP_VSYNC has been activated until the vertical synchronization signal DISP_VSYNC is activated (step S20). If it is determined in this determination that the vertical synchronization signal DISP_VSYNC has been activated, the pen detection operation control circuit 21 activates the synchronization signal INT_VS_EMR_G for pen detection (step S21). By this activation, the pen detection circuit 23 will execute a global scan once.

[0052] The pen detection operation control circuit 21 that has activated the synchronization signal INT_VS_EMR_G for pen detection in step S21 performs the same processes as steps S16 and S17 shown in FIG. 5 (steps S22 and S23). That is, the pen detection operation control circuit 21 determines whether or not the electromagnetic induction pen 2 has been detected as a result of the activation in step S21 (step S22). If a negative result is obtained, by referring to the status flag IDLE stored in the host processor 31, the pen detection operation control circuit 21 determines whether the host processor 31 is in the idle state or the normal state (step S23). The pen detection operation control circuit 21 that has obtained an affirmative result in step S22 moves to step S30 in FIG. 7 and continues the process. Also, when the pen detection operation control circuit 21 obtains a determination result of the normal state in step S23 executed in response to the negative result in step S22, it returns to step S20 and continues the process. When a determination result of the idle state is obtained, it moves to step S11 in FIG. 5 and continues the process.

[0053] Next, referring to FIG. 7, the pen detection operation control circuit 21 that has transitioned to step S30 operates the pen detection circuit 23 in the sector scan mode. Therefore, each time the vertical synchronization signal DISP_VSYNC is activated, a process is performed to activate the synchronization signal INT_VS_EMR_S for pen detection twice in synchronization with the vertical synchronization signal DISP_VSYNC (steps S30 to S33).

[0054] Specifically, the pen detection operation control circuit 21 determines whether the vertical synchronization signal DISP_VSYNC has been activated (step S30). If it is determined that it has not been activated, the process of step S30 is repeated. On the other hand, if it is determined that it has been activated, the synchronization signal INT_VS_EMR_S for pen detection is activated (step S31). After that, it is determined whether a predetermined time has elapsed (step S32). If it is determined that the predetermined time has elapsed, the synchronization signal INT_VS_EMR_S for pen detection is activated again (step S33).

[0055] After step S33 is completed, the pen detection operation control circuit 21 determines whether the electromagnetic induction pen 2 has been detected as a result of the activation in step S31 or step S33 (step S34). If a negative result is obtained, the process moves to step S20 to cause the pen detection circuit 23 to perform a global scan. On the other hand, if a positive result is obtained in step S34, the pen detection operation control circuit 21 returns to step S30 and repeats the above process. As a result, while the pen detection circuit 23 is detecting the electromagnetic induction pen 2, the sector scan is executed twice for each frame period F shown in FIG. 3.

[0056] As described above, according to the sensor controller 30 according to the present embodiment, before the electromagnetic induction pen 2 is detected, the touch detection operation is executed in synchronization with the pixel driving of the display 42, and the pen detection operation is executed in synchronization with the touch detection operation. On the other hand, when the touch detection operation stops in response to the detection of the electromagnetic induction pen 2, the pen detection operation is executed in synchronization with the pixel driving of the display 42. Therefore, it is possible to reliably suppress the interference between the signal used for the pen detection operation and the signal used for the pixel driving of the display 42.

[0057] Next, the position detection system 1 according to the second embodiment of the present invention will be described. The position detection system 1 according to the present embodiment is different from the position detection system 1 according to the first embodiment in terms of the internal processing of the sensor controller 30, and is the same as the position detection system 1 according to the first embodiment in other respects. Hereinafter, the description will focus on the differences from the position detection system 1 according to the first embodiment.

[0058] FIG. 8 is a diagram showing the internal configuration of the sensor controller 30 according to the present embodiment. As can be understood by comparing this figure with FIG. 2, the pen detection operation control circuit 21 according to the present embodiment generates a pen detection operation synchronization signal EMR_VSYNC and a touch detection enable signal Enable_TP instead of the pen detection operation synchronization signals INT_VS_EMR_G and INT_VS_EMR_S, and supplies both of them to the pen detection circuit 23 and only the touch detection enable signal Enable_TP to the touch detection circuit 22. In the present embodiment, the state flags IDLE and PFLG are not used.

[0059] When the touch detection enable signal Enable_TP is activated, the pen detection circuit 23 according to this embodiment performs one global scan each time the synchronization signal EMR_VSYNC for pen detection operation is activated. When the touch detection enable signal Enable_TP is deactivated, the pen detection circuit 23 is configured to execute one sector scan each time the synchronization signal EMR_VSYNC for pen detection operation is activated. In this embodiment, idle scan is not used.

[0060] The touch detection operation control circuit 20 according to this embodiment is configured to generate the synchronization signal TP_VSYNC for touch detection operation in synchronization with the vertical synchronization signal DISP_VSYNC regardless of whether the electromagnetic induction pen 2 is detected by the pen detection circuit 23. On the other hand, when the touch detection enable signal Enable_TP is activated, the touch detection circuit 22 according to this embodiment performs a touch detection operation in response to the activation of the synchronization signal TP_VSYNC for touch detection operation. When the touch detection enable signal Enable_TP is deactivated, the touch detection circuit 22 is configured not to perform a touch detection operation regardless of the state of the synchronization signal TP_VSYNC for touch detection operation.

[0061] FIG. 9 is a time chart showing each signal according to the present embodiment, as well as the operations and operation modes of the sensor controller 30. The touch detection signal TP_TX shown in FIG. 9 is a signal transmitted by the touch detection circuit 22 to each of a plurality of first linear electrodes in the touch sensor 41 in order to derive the position of the passive pointer. The black-filled area shown in FIG. 9 indicates that the touch detection signal TP_TX is being transmitted. The EMR transmission signal EMR_TX is an alternating current supplied by the pen detection circuit 23 to one of a plurality of first loop coils in the EMR sensor 43. The black-filled area shown in FIG. 9 indicates that the EMR transmission signal EMR_TX is being supplied. The EMR reception signal EMR_RX represents the one with the highest detection intensity among the alternating currents detected by the pen detection circuit 23 in each of a plurality of second loop coils in the EMR sensor 43. The black-filled area shown in FIG. 9 represents the detection intensity of the EMR reception signal EMR_RX. The EMR position derivation processing state EMR_CALC indicates the state of derivation of the position of the electromagnetic induction pen 2 by the pen detection circuit 23. The black-filled area shown in FIG. 9 indicates that this derivation is being executed. These points are the same in FIG. 14 described later.

[0062] As shown in FIG. 9, the pen detection operation control circuit 21 according to this embodiment activates the touch detection enable signal Enable_TP in response to the detection of the electromagnetic induction pen 2 at time t1, and deactivates the touch detection enable signal Enable_TP in response to the disappearance of the detection of the electromagnetic induction pen 2 at time t2 (that is, the loss of the electromagnetic induction pen 2). Further, the pen detection operation control circuit 21 generally activates the pen detection operation synchronization signal EMR_VSYNC in synchronization with the touch detection operation synchronization signal TP_VSYNC generated by the touch detection operation control circuit 20. On the other hand, while the electromagnetic induction pen 2 is being detected (between time t1 and time t2 in FIG. 9), each time the vertical synchronization signal DISP_VSYNC generated by the host processor 31 is activated, the pen detection operation synchronization signal EMR_VSYNC is configured to be activated three times. As a result, when the pen detection circuit 23 is not detecting the electromagnetic induction pen 2, it performs a pen detection operation (specifically, a global scan) in synchronization with the touch detection operation. On the other hand, when the electromagnetic induction pen 2 is detected by this pen detection operation, each time the vertical synchronization signal DISP_VSYNC is activated, three pen detection operations (specifically, sector scans) are performed in synchronization with the pixel driving of the display 42. Note that the pen detection circuit 23 may perform one sector scan by dispersing it among these three pen detection operations. Further, when the pen detection circuit 23 is not detecting the electromagnetic induction pen 2, the touch detection circuit 22 performs a touch detection operation in synchronization with the pixel driving of the display 42, and when the pen detection circuit 23 is detecting the electromagnetic induction pen 2, the touch detection circuit 22 does not perform a touch detection operation.

[0063] In this embodiment, unlike the first embodiment, even when the electromagnetic induction pen 2 is detected by the pen detection circuit 23, the generation of the synchronization signal TP_VSYNC for the touch detection operation by the touch detection operation control circuit 20 is not stopped. Nevertheless, the reason why the pen detection operation control circuit 21 performs the above-described operation is that when the touch detection operation is performed, it is essential to perform the pen detection operation in direct synchronization with the touch detection operation in order to avoid the touch detection operation and the pen detection operation from becoming mutual noise. On the other hand, when the touch detection operation is not performed, such a necessity does not exist. Rather, in order to avoid the pixel driving of the display 42 and the pen detection operation from becoming mutual noise, it is preferable to perform the pen detection operation in direct synchronization with the pixel driving of the display 42.

[0064] FIG. 10 is a flowchart showing the processing of the touch detection operation control circuit 20 according to this embodiment, and FIGS. 11 and 12 are flowcharts showing the processing of the pen detection operation control circuit 21 according to this embodiment. Hereinafter, with reference to these figures, the operation of the sensor controller 30 according to this embodiment will be described in more detail again.

[0065] First, referring to FIG. 10, the operation of the touch detection operation control circuit 20 according to this embodiment is the same as the operation of the touch detection operation control circuit 20 according to the first embodiment shown in FIG. 4 (steps S40 to S43), except that there is no determination process of the state flag PFLG. Therefore, according to the touch detection operation control circuit 20 according to this embodiment, regardless of whether the pen detection circuit 23 is detecting the electromagnetic induction pen 2, the touch detection circuit 22 is supplied with an execution instruction for the touch detection operation twice for each frame period F shown in FIG. 9. However, as described above, the touch detection circuit 22 according to this embodiment does not perform the touch detection operation when the touch detection enable signal Enable_TP is inactive. Eventually, when the pen detection circuit 23 is detecting the electromagnetic induction pen 2, the touch detection operation is not executed.

[0066] Next, referring to FIG. 11, the pen detection operation control circuit 21 according to the present embodiment first activates the touch detection enable signal Enable_TP (step S50), creates a state in which the touch detection operation is performed by the touch detection circuit 22, and enters the pen detection circuit 23 into the global scan mode. Subsequently, the pen detection operation control circuit 21 repeatedly performs a process of determining whether or not the touch detection operation synchronization signal TP_VSYNC has been activated until the touch detection operation synchronization signal TP_VSYNC is activated (step S51), and activates the pen detection operation synchronization signal EMR_VSYNC in response to determining that the touch detection operation synchronization signal TP_VSYNC has been activated (step S52). Thereafter, the pen detection operation control circuit 21 determines whether or not the electromagnetic induction pen 2 has been detected by the pen detection circuit 23 (step S53). If it is determined that the pen has not been detected, the process returns to step S51. On the other hand, if it is determined that the pen has been detected, the process proceeds to step S60 in FIG. 12.

[0067] Next, referring to FIG. 12, the pen detection operation control circuit 21 that has transitioned to step S60 makes the touch detection operation by the touch detection circuit 22 not performed by inactivating the touch detection enable signal Enable_TP (step S60), and also enters the pen detection circuit 23 into the sector scan mode. Subsequently, the pen detection operation control circuit 21 determines whether the vertical synchronization signal DISP_VSYNC is activated (step S61). If it is determined that it is not activated, the process of step S61 is repeated. On the other hand, if it is determined that it is activated, the synchronization signal EMR_VSYNC for pen detection operation is activated (step S62). Thereafter, it is determined whether a predetermined time has elapsed (step S63). If it is determined that the predetermined time has elapsed, the synchronization signal EMR_VSYNC for pen detection operation is activated again (step S64). Then, the pen detection operation control circuit 21 further determines whether a predetermined time has elapsed (step S65). If it is determined that the predetermined time has elapsed, the synchronization signal EMR_VSYNC for pen detection operation is activated for the third time (step S66). As a result, each time the vertical synchronization signal DISP_VSYNC is activated, the detection operation of the electromagnetic induction pen 2 by the pen detection circuit 23 is executed three times.

[0068] After step S66 ends, the pen detection operation control circuit 21 determines whether the electromagnetic induction pen 2 has been detected as a result of the activation in steps S62, S64, and S66 (step S67). If a negative result is obtained, the touch detection enable signal Enable_TP is activated (step S68), and the process proceeds to step S51 in FIG. 11. On the other hand, if a positive result is obtained in step S67, the pen detection operation control circuit 21 returns to step S61 and repeats the above process.

[0069] As described above, according to the sensor controller 30 according to the present embodiment, before the electromagnetic induction pen 2 is detected, the touch detection operation is executed in synchronization with the pixel driving of the display 42, and the pen detection operation is executed in synchronization with the touch detection operation. On the other hand, when the touch detection operation stops in response to the detection of the electromagnetic induction pen 2, the pen detection operation is executed in synchronization with the pixel driving of the display 42 even though the generation of the synchronization signal TP_VSYNC for the touch detection operation by the touch detection operation control circuit 20 has not stopped. Therefore, it is possible to surely suppress the interference between the signal used for the pen detection operation and the signal used for the pixel driving of the display 42.

[0070] Next, the position detection system 1 according to the third embodiment of the present invention will be described. The position detection system 1 according to the present embodiment is different from the position detection system 1 according to the second embodiment in that it uses a synchronization signal EMR_HSYNC for pen detection operation that is synchronized with the horizontal synchronization signal DISP_HSYNC, and is the same as that of the position detection system 1 according to the second embodiment in other respects. Hereinafter, the description will focus on the differences from the position detection system 1 according to the second embodiment.

[0071] FIG. 13 is a diagram showing the internal configuration of the sensor controller 30 according to the present embodiment. As can be understood by comparing this figure with FIG. 8, the pen detection operation control circuit 21 according to the present embodiment is configured to supply the pen detection circuit 23 with the synchronization signal EMR_HSYNC for pen detection operation instead of the synchronization signal EMR_VSYNC for pen detection operation. In the present embodiment, the synchronization signal EMR_VSYNC for pen detection operation is used only as an internal signal of the pen detection operation control circuit 21 and is not supplied to the pen detection circuit 23.

[0072] When the touch detection enable signal Enable_TP is activated, the pen detection circuit 23 according to the present embodiment performs one global scan each time the synchronization signal EMR_HSYNC for pen detection operation is activated. When the touch detection enable signal Enable_TP is deactivated, the pen detection circuit 23 is configured to perform one sector scan each time the synchronization signal EMR_HSYNC for pen detection operation is activated.

[0073] FIG. 14 is a time chart showing each signal according to the present embodiment, as well as the operation and operation modes of the sensor controller 30. As shown in the figure, when the electromagnetic induction pen 2 is not detected, the pen detection operation control circuit 21 according to the present embodiment is configured to activate the pen detection operation synchronization signal EMR_HSYNC twice each time the pen detection operation synchronization signal EMR_VSYNC synchronized with the touch detection operation synchronization signal TP_VSYNC is activated. Further, when the electromagnetic induction pen 2 is detected, the pen detection operation control circuit 21 is configured to activate the pen detection operation synchronization signal EMR_HSYNC five times at a timing synchronized with the horizontal synchronization signal DISP_HSYNC each time the pen detection operation synchronization signal EMR_VSYNC synchronized with the vertical synchronization signal DISP_VSYNC is activated. As a result, when the electromagnetic induction pen 2 is not detected, the pen detection circuit 23 performs two pen detection operations (specifically, global scans) each time the touch detection operation synchronization signal TP_VSYNC is activated. On the other hand, when the electromagnetic induction pen 2 is detected by this pen detection operation, the pen detection circuit 23 performs ten pen detection operations (specifically, sector scans) synchronized with the pen detection operation synchronization signal EMR_HSYNC each time the vertical synchronization signal DISP_VSYNC is activated. Note that the pen detection circuit 23 may perform one global scan by dispersing it among the above two pen detection operations, or may perform one global scan by dispersing it among the above ten pen detection operations (or five pen detection operations executed in response to one activation of the pen detection operation synchronization signal EMR_VSYNC).

[0074] FIG. 15 and FIG. 16 are flowcharts showing the processing of the pen detection operation control circuit 21 according to the present embodiment. Further, FIG. 17 is a flowchart showing the specific content of the EMR-HSYNC activation process shown in FIG. 16. Hereinafter, with reference to these figures, the operation of the sensor controller 30 according to the present embodiment will be described in more detail again.

[0075] First, referring to FIG. 15, steps S70 to S72 in the operation of the pen detection operation control circuit 21 according to the present embodiment are the same as steps S50 to S52 of the pen detection operation control circuit 21 according to the second embodiment shown in FIG. 11. After activating the synchronization signal EMR_VSYNC for pen detection operation in step S72, the pen detection operation control circuit 21 according to the present embodiment activates the synchronization signal EMR_HSYNC for pen detection operation (step S73), waits for a predetermined time (step S74), and then activates the synchronization signal EMR_HSYNC for pen detection operation again (step S75). Thereafter, the pen detection operation control circuit 21 determines whether the electromagnetic induction pen 2 is detected by the pen detection circuit 23 as a result of the activation in steps S73 and S75 (step S76). If it is determined that the pen is not detected, the process returns to step S71, while if it is determined that the pen is detected, the process proceeds to step S80 of FIG. 16.

[0076] Next, referring to FIG. 16, a series of processes (steps S80 to S88) shown in FIG. 16 are the same as a series of processes (steps S60 to S68) shown in FIG. 12, except that the activation of the synchronization signal EMR_VSYNC for pen detection operation (steps S82, S85) is only performed twice in response to one activation of the vertical synchronization signal DISP_VSYNC, and the EMR-HSYNC activation process (steps S83, S86) is executed after activating the synchronization signal EMR_VSYNC for pen detection operation.

[0077] Regarding the EMR-HSYNC activation process executed in steps S83 and S86, referring to FIG. 17, the pen detection operation control circuit 21 first sets 0 to a variable N which is a counter (step S90), and repeatedly performs a process of determining whether the horizontal synchronization signal DISP_HSYNC is activated until the horizontal synchronization signal DISP_HSYNC is activated (step S91). When it is determined in this determination that the horizontal synchronization signal DISP_HSYNC is activated, the pen detection operation control circuit 21 determines whether the remainder when the variable N is divided by 2 is 1 (step S92). And when it is determined that it is 1, while activating the synchronization signal EMR_HSYNC for pen detection operation (step S93), when it is determined that it is 0, the activation of the synchronization signal EMR_HSYNC for pen detection operation is not performed, and the process proceeds to step S94.

[0078] In step S94, the pen detection operation control circuit 21 adds 1 to N (step S94), and then determines whether N is 10 or more (step S95). And when it is determined that N is not 10 or more, the process returns to step S91 to continue the process, and when it is determined that N is 10 or more, the EMR-HSYNC activation process ends. By the above process, the pen detection operation control circuit 21 activates the synchronization signal EMR_HSYNC for pen detection operation 5 times each time the synchronization signal EMR_VSYNC for pen detection operation is activated. Also, the horizontal synchronization signal DISP_HSYNC is activated when the activation of the horizontal synchronization signal DISP_HSYNC is the even number of times counted from the activation of the immediately preceding synchronization signal EMR_VSYNC for pen detection operation.

[0079] As described above, even with the sensor controller 30 according to the present embodiment, before the electromagnetic induction pen 2 is detected, the touch detection operation is executed in synchronization with the pixel driving of the display 42, and the pen detection operation is executed in synchronization with the touch detection operation. On the other hand, when the touch detection operation stops in response to the detection of the electromagnetic induction pen 2, the pen detection operation is executed in synchronization with the pixel driving of the display 42 even though the generation of the synchronization signal TP_VSYNC for the touch detection operation by the touch detection operation control circuit 20 has not stopped. Therefore, it is possible to reliably suppress the interference between the signal used for the pen detection operation and the signal used for the pixel driving of the display 42.

[0080] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist thereof.

Explanation of Reference Numerals

[0081] 1 Position detection system 2 Electromagnetic induction pen 3 Position detection device 3a Panel surface 20 Touch detection operation control circuit 21 Pen detection operation control circuit 22 Touch detection circuit 23 Pen detection circuit 30 Sensor controller 31 Host processor 41 Touch sensor 42 Display 43 EMR sensor DISP_VSYNC Vertical synchronization signal DISP_HSYNC Horizontal synchronization signal EMR_VSYNC, EMR_HSYNC, INT_VS_EMR_G, INT_VS_EMR_S Synchronization signals for pen detection operation EMR_TX EMR transmission signal EMR_RX EMR reception signal EMR_CALC EMR position derivation processing status Enable_TP Touch detection enable signal F Frame period IDLE, PFLG Status flag TP_VSYNC Synchronization signal for touch detection operation TP_TX Signal for touch detection

Claims

1. A sensor controller connected to an EMR sensor disposed overlapping a display, performing an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation for detecting a touch by a passive pointer within a panel surface of the display, when the electromagnetic induction pen is detected, performing an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with pixel driving of the display, the sensor controller.

2. The touch detection operation is executed using a touch sensor disposed overlapping the display, when the electromagnetic induction pen is detected, stopping the touch detection operation, The sensor controller according to claim 1.

3. The operation for detecting the electromagnetic induction pen executed in synchronization with the touch detection operation is executed with lower power than the operation for detecting the electromagnetic induction pen executed in synchronization with pixel driving of the display, The sensor controller according to claim 1.

4. The operation for detecting the electromagnetic induction pen executed in synchronization with the touch detection operation and the operation for detecting the electromagnetic induction pen executed in synchronization with pixel driving of the display are operations for detecting the electromagnetic induction pen over the entire panel surface, The sensor controller according to claim 3.

5. The operation for detecting the electromagnetic induction pen executed in synchronization with the touch detection operation is an operation for detecting the electromagnetic induction pen over a longer time than the operation for detecting the electromagnetic induction pen executed in synchronization with pixel driving of the display, The sensor controller according to claim 4.

6. after detecting the electromagnetic induction pen by the operation for detecting the electromagnetic induction pen executed in synchronization with pixel driving of the display, performing the operation for detecting the electromagnetic induction pen for updating the position of the already detected electromagnetic induction pen in synchronization with pixel driving of the display, The sensor controller according to claim 4 or 5.

7. The operation for detecting the electromagnetic induction pen executed in synchronization with pixel driving of the display is the operation for detecting the electromagnetic induction pen for updating the position of the already detected electromagnetic induction pen, The sensor controller according to claim 1 or 2.

8. The operation for detecting the electromagnetic induction pen, which is executed in synchronization with the pixel driving of the display, is executed in synchronization with the horizontal synchronization signal of the display. The sensor controller according to claim 7.

9. When the electromagnetic induction pen is not detected as a result of performing the operation for detecting the electromagnetic induction pen that is executed in synchronization with the pixel driving of the display, an operation for detecting the electromagnetic induction pen is performed in synchronization with the touch detection operation. The sensor controller according to claim 7.

10. A method executed by a sensor controller connected to an EMR sensor disposed overlapping a display, the method comprising: performing an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation for detecting a touch by a passive pointer within the panel surface of the display; when the electromagnetic induction pen is detected, performing an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with the pixel driving of the display; A method including the above.

11. A display, an EMR sensor and a touch sensor disposed overlapping the display, a sensor controller connected to each of the EMR sensor and the touch sensor, A position detection device including: The sensor controller: performs an operation for detecting an electromagnetic induction pen using the EMR sensor in synchronization with a touch detection operation performed using the touch sensor to detect a touch by a passive pointer within the panel surface of the display; when the electromagnetic induction pen is detected, performs an operation for detecting the electromagnetic induction pen using the EMR sensor in synchronization with the pixel driving of the display. Position detection device.

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