Position detection device and position detection method

Abstract

To make it possible to detect a position of a second position indicator even after shifting to local scanning of a first position indicator.SOLUTION: A position detecting device 1 includes a sensor 10, and a sensor controller 20 for detecting a first position indicated by a position indicator 2b and a second position indicated by a position indicator 2a via the sensor 10. In a case of shifting to local scanning that is position detection in a region in the vicinity of a detected position by detecting the first position or the second position, the sensor controller 20 determines whether or not a frequency used in the local scan is a second frequency. When it is determined that the frequency used in the local scan is not the second frequency, the sensor controller performs position detection by the second frequency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a position detection device and a position detection method, and more particularly to a position detection device and a position detection method that appropriately detect positions indicated by a plurality of position indicators. [Background technology]

[0002] Electromagnetic induction input devices are known as input devices for electronic devices such as tablet computers and smartphones. This type of input device includes, for example, a pen-shaped position indicator and a position detection device with a flat input surface. A user holds the position indicator in their hand and performs input operations by sliding the position indicator across the input surface as if they were writing letters or pictures on a piece of paper.

[0003] The position pointer is configured with a resonant circuit including an inductor and a capacitor. The position detection device is configured with multiple loop coils arranged within the input surface. Briefly, the position detection device detects the position of the position pointer by first generating a magnetic field from one of the loop coils. This generates induced power in the inductor of the position pointer, charging the capacitor. After that, when the position detection device eliminates the magnetic field, a reflected signal is transmitted from the position pointer using the power charged in the capacitor. The position detection device detects the position of the position pointer within the input surface by determining the reception strength of the transmitted reflected signal at each loop coil.

[0004] Patent Document 1 discloses a position pointer having resonant circuits at both ends. The resonant circuits at both ends are configured so that the phases of the reflected signals relative to the signal from the position detection device are different from each other, allowing the position detection device to distinguish and detect them. As a result, for example, one end can be used as a pen and the other end as an eraser, allowing the user to use the position pointer as if they were using a pencil with an eraser. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-69350 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, typical stationery items often have erasers separate from the pencil, in addition to those attached to the end of a pencil. Therefore, the inventors of the present application are considering using separate devices for the position indicators, one with an eraser function and one with a pen function. In this case, the following position detection method can be considered, for example, to distinguish and detect the positions indicated by each position indicator. A different resonance frequency can be assigned to each position indicator. First, a global scan (scanning the entire sensor) using each resonance frequency is performed in a time-division manner. When a position indicated by one of the position indicators is detected by the global scan, the method transitions to a local scan (scanning the area of ​​the sensor near the previously detected position) of the position indicated by that position indicator.

[0007] However, when such a position detection method is adopted, after a position indicated by a certain position indicator is detected, it becomes impossible to detect a position indicated by another position indicator. Therefore, even when a position indicated by a certain position indicator is detected, it is required to be able to detect a position indicated by another position indicator. For example, even when a position indicated by a position indicator having an eraser function is detected, it is required to be able to detect a position indicated by a pen position indicator when a position indicator having a pen function approaches.

[0008] Therefore, one object of the present invention is to provide a position detection device and a position detection method that can appropriately detect positions indicated by a plurality of position indicators depending on the situation. [Means for solving the problem]

[0009] The position detection device of the present invention comprises a sensor and a controller that detects a first position indicated by a first position indicator and a second position indicated by a second position indicator via the sensor, and is characterized in that, after transitioning from a state in which neither the first position nor the second position has been detected to a state in which the first position has been detected, the controller continues detecting the first position while stopping detecting the second position, whereas, after transitioning from a state in which neither the first position nor the second position has been detected to a state in which the second position has been detected, the controller continues detecting both the second position and the first position.

[0010] The position detection method of the present invention is a position detection method that detects a first position indicated by a first position indicator and a second position indicated by a second position indicator via a sensor, and is characterized in that, after transitioning from a state in which neither the first position nor the second position is detected to a state in which the first position is detected, detection of the second position is stopped while continuing detection of the first position, while, after transitioning from a state in which neither the first position nor the second position is detected to a state in which the second position is detected, detection of both the second position and the first position is continued. [Effects of the Invention]

[0011] According to the present invention, the positions indicated by the plurality of position indicators can be detected appropriately depending on the situation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing the appearance of a position detection device 1 and position indicators 2a and 2b according to a first embodiment of the present invention. [Figure 2] 2 is a diagram showing the internal configuration of a position indicator 2, a sensor 10, and a sensor controller 20. FIG. [Figure 3] FIG. 2 is a diagram showing an outline of a position detection method performed by a control unit 28 according to the first embodiment of the present invention. [Figure 4] FIG. 1 is a process flow diagram showing a position detection method according to a first embodiment of the present invention. [Figure 5] FIG. 1 is a process flow diagram showing a position detection method according to a first embodiment of the present invention. [Figure 6] 4, 11, and 13. (a) is a processing flow diagram showing details of the Y-axis side global scan executed in step S2 of FIG. 4, FIG. 11, and FIG. 13. (b) is a processing flow diagram showing details of the Y-axis side global scan executed in step S7 of FIG. 4, FIG. 11, and FIG. 13. [Figure 7] 12A is a process flow diagram showing details of the local scan performed in step S11 of FIG. 5, FIG. 12, and FIG. 13, and FIG. 12B is a process flow diagram showing details of the partial global scan performed in step S43 of FIG. 5 and step S64 of FIG. 12. [Figure 8] FIG. 14 is a diagram schematically showing the resonance levels detected in steps S2 and S7 of FIGS. 4, 11, and 13. [Figure 9] FIG. 10 is a diagram showing the appearance of a position detection device 1 and position indicators 2a to 2c according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an outline of a position detection method performed by a control unit 28 according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a process flow diagram showing a position detection method according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a process flow diagram showing a position detection method according to a second embodiment of the present invention. [Figure 13] FIG. 1 is a process flow diagram showing a specific example of a position detection method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0014] FIG. 1 is a diagram showing the appearance of a position detection device 1 and position indicators 2a and 2b according to a first embodiment of the present invention. The position detection device 1 is a computer such as a tablet terminal having an input surface 10a, and as shown in FIG. 1, is configured with a sensor 10, a sensor controller 20, and a host processor 40. Of these, the sensor 10 and the sensor controller 20 will be described in detail later. The host processor 40 is a central processing unit of the position detection device 1, which is a computer, and performs processes such as generating stroke data based on coordinates input from the sensor controller 20, storing the generated stroke data in a storage device, transmitting the generated stroke data to another computer, and rendering the generated stroke data to display it on a display device.

[0015] The position indicators 2a and 2b each function as an input device for the position detection device 1. As shown in FIG. 1, the position indicator 2a with a pen function is pen-shaped, and the position indicator 2b with an eraser function is eraser-shaped. As will be described in detail later, the position detection device 1 can distinguish and detect these indicators based on the difference in resonance frequency, and when generating the above-mentioned stroke data, the position indicator 2a is treated as a pen and the position indicator 2b is treated as an eraser. In the following description, the position indicators 2a and 2b (and the position indicator 2c described in the second embodiment) may be collectively referred to as the position indicator 2.

[0016] 2 is a diagram showing the internal configurations of the position indicator 2, the sensor 10, and the sensor controller 20. First, focusing on the position indicator 2, the position indicator 2 is configured with an LC resonant circuit including an inductor 3 and a capacitor 4. The inductance of the inductor 3 and the capacitance of the capacitor 4 are set so that the resonant frequency of this LC resonant circuit differs for each type of position indicator 2. The inductor 3 generates an induced voltage in response to the magnetic field supplied from the sensor 10 and charges the capacitor 4. After the supply of the magnetic field from the sensor 10 stops, the inductor 3 uses the charge accumulated in the capacitor 4 to transmit a reflected signal to the position detection device 1.

[0017] As shown in Fig. 2, the sensor 10 has a configuration in which a plurality of loop coils LC are arranged in a rectangular planar area. One end of each loop coil LC is grounded, and the other end is connected to the sensor controller 20. In Fig. 3, as an example of the plurality of loop coils LC, m loop coils X1 to X2 on the X-axis side extending in the y direction are shown. m and n Y-axis side loop coils Y1 to Y2 extending in the x direction perpendicular to the y direction. n In the figure, m and n are each, for example, 40.

[0018] The sensor controller 20 detects a position (first position) on the input surface 10a indicated by the position indicator 2a and a position (second position) on the input surface 10a indicated by the position indicator 2b via the sensor 10. As shown in FIG. 2 , the sensor controller 20 is configured to include a selection circuit 21, a switch circuit 22, an amplifier 23, a detection circuit 24, a low-pass filter (LPF) 25, a sample-and-hold circuit (S / H) 26, an analog-to-digital conversion circuit (A / D) 27, a control unit 28, an oscillator 29, and a current driver 30.

[0019] The other end of each loop coil LC is connected to the selection circuit 21. The selection circuit 21 selects one or more of the multiple loop coils LC in accordance with control from the control unit 28, and connects the selected ones to the switch circuit 22.

[0020] The switch circuit 22 is a switch having one common terminal and two selection terminals, and is configured to be able to switch the selection terminal connected to the common terminal under control of the control unit 28. The common terminal of the switch circuit 22 is connected to the selection circuit 21, one selection terminal is connected to the input terminal of the amplifier 23, and the other selection terminal is connected to the output terminal of the current driver 30.

[0021] The amplifier 23 is a circuit that amplifies the voltage signal supplied from the selection circuit 21 via the switch circuit 22 and outputs the amplified signal to the detection circuit 24. The detection circuit 24 is a circuit that generates an envelope signal by performing envelope detection on the voltage signal output from the amplifier 23 and outputs the envelope signal to the low-pass filter 25. The low-pass filter 25 serves to remove high-frequency components from the envelope signal generated by the detection circuit 24. The sample-and-hold circuit 26 is configured to sample and hold the envelope signal, from which high-frequency components have been removed by the low-pass filter 25, at predetermined time intervals. The analog-to-digital conversion circuit 27 generates a digital signal by performing analog-to-digital conversion on the signal held by the sample-and-hold circuit 26 and outputs the digital signal to the control unit 28.

[0022] The control unit 28 is a processor that operates according to a program stored in a storage device, and is connected to the host processor 40 shown in Fig. 1. The control unit 28 controls the selection circuit 21, the switch circuit 22, the sample-and-hold circuit 26, the analog-to-digital conversion circuit 27, and the oscillator 29, and is configured to execute processes such as detecting the position of the position indicator 2 based on the digital signal supplied from the analog-to-digital conversion circuit 27, and outputting the coordinates indicating the detected position to the host processor 40 in association with the type of the position indicator 2.

[0023] 3 is a diagram showing an outline of a position detection method performed by the control unit 28 according to this embodiment. (a) in FIG. 3 shows a global scan mode in which a global scan is performed to scan the entire sensor 10 to detect a position indicated by each position indicator 2, and (b) in FIG. 3 shows a local scan mode in which a local scan is performed to scan an area of ​​the sensor 10 near a position that has already been detected. (b) in FIG. 3 shows a local scan mode for detecting a position indicated by a position indicator 2b with an eraser function, which will be described in detail later. Between the global scan mode and the local scan mode, there is an intermediate mode for confirming a position detected in the global scan mode.

[0024] After entering the global scan mode, the control unit 28 is configured to time-share a global scan of each position indicator 2 at a frequency of once per time TG. "PGS" shown in Fig. 3 represents a global scan (GlobalScan) of the position indicator 2a having a pen function, and "EGS" represents a global scan (GlobalScan) of the position indicator 2a having an eraser function.

[0025] The time TG is set to, for example, 0.125 seconds (8 Hz). The control unit 28 divides the global scan of each position indicator 2 into a Y-axis global scan in which the Y-axis loop coil LC is scanned and an X-axis global scan in which the X-axis loop coil LC is scanned, and in the global scan mode, repeatedly executes the Y-axis global scan of each position indicator 2 in a time-division manner. Note that the symbol "y" added to the end of each of "PGS" and "EGS" in FIG. 3 indicates that this is a Y-axis global scan. When any of the position indicators 2 is detected in these Y-axis global scans, the control unit 28 is configured to transition to the intermediate mode for that position indicator 2.

[0026] In the global scan mode according to this embodiment, the order in which the position indicators undergo the Y-axis side global scan is determined in advance, and when the global scan mode is entered from another mode, the Y-axis side global scan of each position indicator is started in this predetermined order. In the following description, a position indicator for which the Y-axis side global scan is performed relatively earlier in the global scan mode is referred to as a "priority position indicator," and a position indicator for which the Y-axis side global scan is performed relatively later is referred to as a "non-priority position indicator." As shown in FIG. 3, the Y-axis side global scan is performed in the order of the position indicator 2a and the position indicator 2b. Therefore, in this embodiment, the position indicator 2a having the pen function is the priority position indicator, and the position indicator 2b having the eraser function is the non-priority position indicator.

[0027] The intermediate mode will now be described. Upon entering the intermediate mode, the control unit 28 is configured to execute an X-axis side global scan for the position indicator 2 detected in the global scan mode and a determination process for confirming the detection. The determination process is a process for determining whether the detection results of the Y-axis side global scan and the X-axis side global scan satisfy predetermined detection conditions. As will be described in detail later, the predetermined detection conditions include, for example, whether the reception intensity distribution of the reflected signals detected in the Y-axis side global scan and the X-axis side global scan has a predetermined shape. If the position detection is confirmed as a result of the determination process, the control unit 28 transitions to a local scan mode for the position indicator 2 whose position detection has been confirmed. On the other hand, if the position detection is not confirmed, the control unit 28 returns to the global scan mode.

[0028] After entering the local scan mode, the control unit 28 is configured to perform a local scan of the target position indicator once every time TL, as shown in FIG. 3(b). TL is set to, for example, approximately 0.0075 seconds (133 Hz), a value smaller than the time TG described above. This is to enable the stroke data described above to be generated with high accuracy. Note that "ELS" in FIG. 3 represents a local scan of the position indicator 2b having an eraser function. The symbols "x" and "y" suffixed to "ELS" represent a scan of the X-axis loop coil LC and a scan of the Y-axis loop coil LC, respectively. As shown in FIG. 3(b), the control unit 28 is configured to sequentially perform a scan of the X-axis loop coil LC and a scan of the Y-axis loop coil LC during one local scan.

[0029] The control unit 28 performs a local scan on the target position indicator once every time TL. Meanwhile, the control unit 28 performs a global scan on the other position indicators 2. In one example of the present embodiment, the global scan on the other position indicators 2 is divided and executed. That is, the control unit 28 is configured to execute a partial global scan (hereinafter referred to as a partial global scan) of the other position indicators 2. A partial global scan is a part of the corresponding global scan, and refers to scanning, for example, two or three loop coils LC. Note that the loop coils LC to be scanned in the partial global scan may include one or both of the Y-axis side loop coils LC and the X-axis side loop coils LC. The specific number of loop coils LC that can be scanned in the partial global scan is determined, for example, in consideration of the time length of the partial global scan.

[0030] In this embodiment, the control unit 28 gives priority to the position indicator 2a having the pen function, and is therefore configured to alternately perform a local scan of the position indicator 2b and a partial global scan of the position indicator 2a when the control unit 28 has entered the local scan mode for the position indicator 2b having the eraser function. Note that "PGSp" shown in FIG. 3 indicates a partial global scan of the position indicator 2a having the pen function. As a result, the control unit 28 continues to detect the positions of both the position indicator 2a and the position indicator 2b after detecting the position of the position indicator 2b in a state where neither the position of the position indicator 2a nor the position indicator 2b has been detected.

[0031] In this embodiment, when the local scan mode for the position indicator 2a having the pen function is entered, the control unit 28 does not perform a partial global scan for the position indicator 2b having the eraser function. That is, after the control unit 28 transitions from a state in which the positions of both the position indicator 2a and the position indicator 2b are not detected to a state in which the position of the position indicator 2a is detected, the control unit 28 continues to detect the position of the position indicator 2a while stopping the detection of the position of the position indicator 2b. This configuration is based on an example of a user's actual situation in which a position is input using the position indicator 2a having the pen function while a position is not input using the position indicator 2b having the eraser function. Of course, depending on the user's actual situation, a partial global scan for the position indicator 2b may be performed when the local scan mode for the position indicator 2a is entered.

[0032] If the position indicator 2a is detected in the partial global scan, the control unit 28 returns to the global scan mode. Since the position indicator 2a is detected in the global scan, after the global scan is completed, the control unit 28 transitions to the local scan mode for the position indicator 2a and continues to detect the position of the position indicator 2a.

[0033] Returning to FIG. 2, oscillator 29 is a circuit configured to be able to generate an AC signal of any frequency (hereinafter referred to as the "detection signal"). The frequency of the detection signal generated by oscillator 29 (hereinafter referred to as the "detection frequency") is controlled by control unit 28. Current driver 30 converts the detection signal output from oscillator 29 into a current signal and supplies it to switch circuit 22.

[0034] A specific method by which the control unit detects the position indicated by the position indicator 2 will be described in more detail below with reference to a processing flow executed by the control unit .

[0035] FIG. 13 is a process flow diagram showing a specific example of a position detection method executed by the control unit 28.

[0036] 13, the control unit 28 first enters the global scan mode (step S1). When entering the global scan mode, the control unit 28 initializes the detection frequency. In this embodiment, the detection frequency thus initialized becomes the resonance frequency of the position pointer 2a (see FIG. 3(a)).

[0037] After entering the global scan mode, the control unit 28 performs a global scan on the Y-axis side (step S2).

[0038] 6(a) is a process flow diagram showing details of the Y-axis side global scan executed in step S2. The control unit 28 is configured to repeat the processes of steps S21 and S22 (step S20) while selecting each loop coil LC on the Y-axis side one by one (specifically, while connecting each loop coil LC to the common terminal of the switch circuit 22 by the selection circuit 21 shown in FIG. 2).

[0039] Step S21 is a process of transmitting a predetermined detection signal from the current loop coil LC (loop coil LC on the Y-axis side) using the current detection frequency for a predetermined time by connecting the switch circuit 22 shown in Fig. 2 to the oscillator 29. If the position pointer 2 having the current detection frequency as its resonant frequency is present in the vicinity of the current loop coil LC, the capacitor 4 shown in Fig. 2 will be charged during step S21.

[0040] In step S22, after the transmission of the detection signal is completed, the switch circuit 22 shown in FIG. 2 is connected to the detection circuit 24 side to scan the current loop coil LC (loop coil LC on the Y-axis side). The scanning here refers to the process of detecting the reception intensity (resonance level) of the reflected signal transmitted by the position pointer 2. The control unit 28 temporarily stores the detected resonance level for each loop coil LC on the Y-axis side.

[0041] Returning to FIG. 13, when the Y-axis side global scan is completed, the control unit 28 determines whether or not any of the multiple resonance levels temporarily stored is equal to or greater than the threshold value (step S3). As a result, if the control unit 28 determines that there is no such resonance level, the control unit 28 switches the detection frequency to the next one (if the current detection frequency is the resonance frequency for the position indicator 2a, the resonance frequency for the position indicator 2b; if the current detection frequency is the resonance frequency for the position indicator 2b, the resonance frequency for the position indicator 2a) (step S4), and the process returns to step S2. By providing this step S4, in the global scan mode, detection of the position of the position indicator 2a by the Y-axis side global scan and detection of the position of the position indicator 2b by the Y-axis side global scan are alternately repeated.

[0042] On the other hand, if the control unit 28 determines in step S3 that the loop coil LC is present, the control unit 28 enters the intermediate mode (step S5), and determines the Y-axis loop coil LC to which the position indicator 2 is closest (hereinafter referred to as the "closest Y-axis loop coil LC") based on the multiple resonance levels temporarily stored in step S2 (step S6). Then, the control unit 28 performs a global scan of the X-axis side of the position indicator 2 (step S7).

[0043] 6(b) is a process flow diagram showing details of the X-axis side global scan executed in step S7. The control unit 28 is configured to repeat the processes of steps S26 and S27 (step S25) while selecting each loop coil LC on the X-axis side one by one (specifically, while connecting each loop coil LC to the common terminal of the switch circuit 22 by the selection circuit 21 shown in FIG. 2).

[0044] Step S26 is a process of connecting the switch circuit 22 shown in Fig. 2 to the oscillator 29 side, thereby transmitting a predetermined detection signal from the nearest Y-axis loop coil LC using the current detection frequency for a predetermined time. At this point, there is a high probability that the position pointer 2 having the current detection frequency as its resonant frequency is located near the nearest Y-axis loop coil LC. Therefore, the capacitor 4 of such a position pointer 2 is charged during step S26.

[0045] In step S27, after the transmission of the detection signal is completed, the switch circuit 22 shown in FIG. 2 is connected to the detection circuit 24 side to scan the current loop coil LC (loop coil LC on the X-axis side). The scanning here also refers to the process of detecting the reception intensity (resonance level) of the reflected signal transmitted by the position pointer 2. The control unit 28 temporarily stores the detected resonance level for each loop coil LC on the X-axis side.

[0046] Returning to FIG. 13, after completing the global scan on the X-axis side, the control unit 28 performs a determination process to confirm the position detection in response to the execution results of steps S2 and S7 (step S8). This determination process, like step S3, includes determining whether any of the multiple resonance levels temporarily stored for each loop coil LC on the X-axis side is equal to or greater than a threshold value, as well as whether the distribution of the resonance levels has a predetermined shape (for example, a convex shape as shown in FIG. 8, which will be described later), whether the phase difference of the electromagnetic resonance is that of a side lobe, and whether the ratio of the resonance levels of the side lobe and the main peak is normal. It may also be possible to perform a local scan once and determine whether the position pointer 2 is detected as a result.

[0047] 8 is a diagram schematically showing the resonance level detected in steps S2 and S7. The horizontal axis of the diagram is the x-axis or y-axis, and the vertical axis is the resonance level. As shown in the diagram, the resonance level detected in steps S2 and S7 is composed of a relatively large peak (main peak) appearing at position Pm shown in the diagram and relatively small peaks (side lobes) appearing on both sides of it (position Ps shown in the diagram). The side lobes are generated because the magnetic field lines generated from the sensor 10 are ring-shaped, and the position pointer 2 is not present at the position of the side lobes.

[0048] 13, the process of step S8 is essentially a process of confirming that the waveform shown in Fig. 8 has been correctly obtained and that the position to be detected is position Pm. In step S8, position Pm is also determined as the position of the position indicator 2.

[0049] If the detection of the position indicator 2 is not confirmed as a result of the determination process performed in step S8, the control unit 28 returns the process to step S1 and re-enters the global scan mode. On the other hand, if the detection of the position indicator 2 is confirmed, the control unit 28 enters the local scan mode (step S10) and starts a local scan of the position indicator 2 (step S11). In this case, the resonance frequency (specified frequency) used in the local scan is the current detection frequency.

[0050] 7(a) is a process flow diagram showing details of the local scan executed in step S11. The control unit 28 is configured to repeat the processes of steps S31 and S32 (step S30) while selecting a predetermined number (e.g., three or four) of Y-axis side loop coils LC one by one in order of proximity to the position of the target position indicator 2 (the position determined in step S8 immediately after switching from the intermediate mode; the position determined in the immediately preceding local scan in the second or subsequent local scans) (specifically, while connecting the coils to the common terminal of the switch circuit 22 by the selection circuit 21 shown in FIG. 2).

[0051] Step S31 is a process of transmitting a predetermined detection signal from the current loop coil LC (Y-axis side loop coil LC) using a specified frequency for a predetermined time by connecting the switch circuit 22 shown in Fig. 2 to the oscillator 29 side. Step S32 is a process of scanning the current loop coil LC by connecting the switch circuit 22 shown in Fig. 2 to the detection circuit 24 side after completing the transmission of the detection signal. The control unit 28 temporarily stores the detected resonance level for each selected loop coil LC.

[0052] Next, the control unit 28 is configured to repeat the processes of steps S34 and S35 while selecting a predetermined number (e.g., three or four) of X-axis side loop coils LC one by one in order of proximity to the position of the target position indicator 2 (specifically, while connecting them to the common terminal of the switch circuit 22 by the selection circuit 21 shown in FIG. 2) (step S33).

[0053] Step S34 is a process of transmitting a predetermined detection signal from the current loop coil LC (X-axis side loop coil LC) using a specified frequency for a predetermined time by connecting the switch circuit 22 shown in Fig. 2 to the oscillator 29 side. Step S35 is a process of scanning the current loop coil LC by connecting the switch circuit 22 shown in Fig. 2 to the detection circuit 24 side after completing the transmission of the detection signal. The control unit 28 temporarily stores the detected resonance level for each selected loop coil LC.

[0054] In step S34, a predetermined detection signal is transmitted from the current loop coil LC, but similar to the case of global scanning, the closest Y-axis loop coil LC to which the position indicator 2 is closest may be determined based on the result of step S30, and the detection signal may be transmitted from the closest Y-axis loop coil LC. Also, although Fig. 7(a) shows an example in which steps S33 to S35 are executed after steps S30 to S32, this order may be reversed.

[0055] Returning to FIG. 13, after the process of step S11 is completed, the control unit 28 determines whether or not the reflected signal has been lost (step S12). The state in which the reflected signal has been lost refers to a case in which a sufficient resonance level has not been detected as a result of scanning each loop coil, such as when the target position indicator 2 has moved away from the input surface 10a. In this case, the control unit 28 returns the process to step S1 and re-enters the global scan mode. On the other hand, if it is determined in step S12 that the reflected signal has not been lost, the control unit 28 determines the position of the position indicator 2 based on the multiple resonance levels temporarily stored in step S11 and supplies coordinates indicating the determined position to the host processor 40 shown in FIG. 1 (step S13). Thereafter, the process returns to step S11 and executes the local scan again.

[0056] In the above-described position detection method, the following two states may occur. Each state will be explained below.

[0057] In the first state, after the mode has been switched to the local scan mode for the position indicator 2b having the eraser function, it becomes impossible to detect the position indicator 2a having the pen function. As an example, there may be a state in which the user leaves the position indicator 2b having the eraser function on the input surface 10a and performs input using the position indicator 2a having the pen function. Therefore, in this state, it is necessary to be able to detect the position indicator 2a having the pen function even after the mode has been switched to the local scan mode for the position indicator 2b having the eraser function.

[0058] The second state is when the process for the position indicator 2a, which is the priority position indicator, proceeds to step S9, but the determination there is negative, preventing the process from proceeding to local scanning. If this state continues, after the position indicator 2a re-enters the global scan mode, the position indicator 2a, which is the priority position indicator, is detected, and the Y-axis global scan of the non-priority position indicators is not performed. As a result, the position indicator 2b, which is the non-priority position indicator, cannot be detected. This state occurs because the detection frequency is initialized in step S1 every time a negative determination is made in step S9. For example, this state can occur when the position indicator 2a having a pen function is left lying on its side on the input surface 10a, and an accurate waveform cannot be obtained in the determination process in step S8. Therefore, it is necessary to avoid the situation where the position indicator 2b, which is the non-priority position indicator, cannot be detected while achieving a rapid global scan by employing the global scan mode and the intermediate mode.

[0059] 4 and 5 are process flow diagrams showing a position detection method executed by control unit 28 to avoid the above-described state. Hereinafter, the position detection method executed by control unit 28 according to this embodiment will be described in detail with reference to these figures.

[0060] 4 and 5 differ from the method shown in Fig. 13 in that step S1 is divided into steps S1a and S1b, that if the determination result of step S9 is negative, the process proceeds to step S40 instead of step S1, and that steps S41 to S44 are executed after step S13. The following description will focus on these differences.

[0061] The control unit 28 executes step S1 by dividing it into steps S1a and S1b as shown in Fig. 4. Step S1a is a process for initializing the detection frequency, and step S1b is a process for entering the global scan mode.

[0062] 4, when the determination result of step S9 is negative, the control unit 28 proceeds to step S40 instead of step S1. Like step S4, step S40 is a process of switching the detection frequency to the next one. After executing step S40, the control unit 28 executes step S1b. As a result, the control unit 28 re-enters the global scan mode without initializing the detection frequency. Therefore, when the control unit 28 transitions to the global scan mode because the position of the position indicator 2a has not been determined in step S9, the control unit 28 first executes a global scan on the Y-axis side of the position indicator 2b. Therefore, by employing the global scan mode and the intermediate mode, a rapid global scan can be achieved while avoiding the position indicator 2b, which is a non-priority position indicator, from being unable to be detected.

[0063] As shown in FIG. 5, the control unit 28 further executes steps S41 to S44 after step S13. More specifically, the control unit 28 first determines whether the current detection frequency is the resonance frequency of the position indicator 2b having the eraser function (step S41). If the control unit 28 determines that the current detection frequency is not the resonance frequency of the position indicator 2b having the eraser function, the control unit 28 returns the process to step S11 and continues the local scan of the position indicator 2a. On the other hand, if the control unit 28 determines that the current detection frequency is the resonance frequency of the position indicator 2b having the eraser function, the control unit 28 selects a loop coil LC (coil for partial global scan) to be used in the partial global scan (step S42) and then executes a partial global scan of the position indicator 2a (step S43). In step S42, for example, a plurality of loop coils LC including one or both of the Y-axis side and the X-axis side may be selected in order, or the selection may be performed in another order. The resonance frequency (specified frequency) to be used in the partial global scan of step S43 is the resonance frequency (pen frequency) of the position indicator 2a.

[0064] 7(b) is a process flow diagram showing details of the partial global scan executed in step S43 by the control unit 28. As shown in the figure, the control unit 28 is configured to repeat the processes of steps S51 and S52 (step S50) while selecting the loop coils LC (selected in step S42 of FIG. 5) for the partial global scan one by one (specifically, while connecting them to the common terminal of the switch circuit 22 by the selection circuit 21 shown in FIG. 2).

[0065] Step S51 is a process of transmitting a predetermined detection signal from the current loop coil LC using a specified frequency for a predetermined time by connecting the switch circuit 22 shown in Fig. 2 to the oscillator 29. Step S52 is a process of scanning the current loop coil LC by connecting the switch circuit 22 shown in Fig. 2 to the detection circuit 24 after completing the transmission of the detection signal. The control unit 28 temporarily stores the detected resonance level for each selected loop coil LC.

[0066] Returning to FIG. 5, after executing the partial global scan, the control unit 28 determines whether the position indicator 2a has been detected based on whether a reflected signal from the position indicator 2a has been detected (step S44). If the control unit 28 determines that the position indicator 2a has been detected, the control unit 28 returns the process to step S1a, thereby stopping the local scan of the position indicator 2b and re-entering the global scan mode. As a result, the Y-axis side global scan is restarted. However, since the reflected signal from the position indicator 2a has been detected, the control unit 28 transitions to the local scan mode for the position indicator 2a, allowing the user to perform input using the position indicator 2a with a pen function. On the other hand, if the control unit 28 determines that the position indicator 2a has not been detected in step S44, the control unit 28 returns the process to step S11. As a result, the local scan mode for the position indicator 2b continues, allowing the user to continue input using the position indicator 2b with an eraser function.

[0067] As described above, according to the position detecting device 1 and the position detecting method of this embodiment, since the detection of the position indicated by the position indicator 2a continues even after the detection of the position indicated by the position indicator 2b, it is possible to detect the position indicated by the position indicator 2a as well as the position indicated by the position indicator 2b. Therefore, the user can perform input using the position indicator 2a having a pen function without moving the position indicator 2b having an eraser function from the input surface 10a.

[0068] In this embodiment, the case where a partial global scan of the position indicator 2a is performed in the local scan mode for the position indicator 2b has been described, but it goes without saying that a partial global scan of the position indicator 2b may be performed in the local scan mode for the position indicator 2a. This enables the user to perform input using the position indicator 2b with the eraser function without moving the position indicator 2a with the pen function from the input surface 10a.

[0069] Furthermore, according to the position detecting device 1 and the position detecting method of this embodiment, when the detection of the position of the position indicator 2a is not confirmed in the determination process after the end of the X-axis side global scan and the system transitions to the global scan mode, the Y-axis side global scan of the position indicator 2b is executed first. Therefore, by providing the global scan mode and the intermediate mode, it is possible to realize a quick global scan while avoiding the situation where the position indicator 2b, which is a non-priority position indicator, becomes unable to be detected.

[0070] In this embodiment, the position detection device 1 has been described as having both a configuration (e.g., steps S41 to S44) that enables detection of the position indicator 2a even after transitioning to the local scan mode for the position indicator 2b, and a configuration (e.g., steps S1a, S1b, S40) that enables rapid global scanning by providing a global scan mode and an intermediate mode while avoiding the position indicator 2b, which is a non-priority position indicator, from becoming unable to be detected. However, the present invention also includes a position detection device that has either one of these configurations.

[0071] Next, a position detection device 1 and a position detection method according to a second embodiment of the present invention will be described.

[0072] FIG. 9 is a diagram showing the appearance of a position detection device 1 and position indicators 2a to 2c according to a second embodiment of the present invention. The basic configuration of the position detection device 1 is the same as that of the position detection device 1 according to the first embodiment, but differs from the position detection device 1 according to the first embodiment in that it also supports detection of a position indicator 2c. The position indicator 2c has the same basic structure as the position indicator 2a, but differs from the position indicator 2a in that it has a side switch 5 and its resonance frequency differs depending on whether the side switch 5 is pressed or not. Hereinafter, the position indicator 2a will be referred to as pen 1 (P1), the position indicator 2c with its side switch 5 not pressed will be referred to as pen 2 (P2), and the position indicator 2c with its side switch 5 pressed will be referred to as pen 3 (P3). The position indicator 2b, which is an eraser, will also be referred to simply as the eraser.

[0073] FIG. 10 is a diagram showing an outline of a position detection method performed by the control unit 28 according to this embodiment. FIG. 10(a) shows a global scan mode in which a global scan is performed to scan the entire sensor 10 to detect the position of each position indicator 2, and FIG. 10(b) shows a local scan mode in which a local scan is performed to scan an area of ​​the sensor 10 near a position that has already been detected. As will be described in detail later, FIG. 10(b) shows the local scan mode for the position indicator 2b, which is an eraser. Although not shown in FIG. 10, an intermediate mode exists between the global scan mode and the local scan mode for confirming the position detected in the global scan mode, as in the first embodiment.

[0074] One difference from the position detection method shown in Fig. 3 is that the control unit 28, which has entered the global scan mode, performs four types of Y-axis side global scans in a time-division manner. Specifically, the Y-axis side global scans are executed in the order of pen 2 (P2GSy), pen 3 (P3GSy), eraser (EGSy), and pen 1 (P1GSy). Note that, because the four types of Y-axis side global scans are performed in a time-division manner, the length of time TG is twice as long as the length of time TG in the first embodiment.

[0075] 10(b), in this embodiment as well, in the local scan mode for the position indicator 2b, which is an eraser, the local scan of the position indicator 2b and the partial global scan (first partial global scan) of the position indicator 2a are performed alternately. Note that "P1GSp" shown in FIG. 10(b) indicates the partial global scan of the pen 1.

[0076] The key point of this embodiment is that the order of global scans on the Y-axis side of the position indicators 2a and 2b in global scan mode is reversed from that of the first embodiment. In other words, in this embodiment, the pen 1, which is the target of partial global scan, is a non-priority position indicator relative to the eraser, which is the target of local scan. Due to this difference from the first embodiment, in this embodiment, even if the pen 1 is detected by partial global scan, it is necessary to temporarily switch to global scan mode to confirm the detection. However, after switching to global scan mode, the eraser, which is a priority position indicator that has priority over the pen 1, is detected again. As a result, even though the pen 1, which is a non-priority position indicator, is detected by partial global scan, it is not possible to switch to local scan mode for the pen 1. Therefore, it is necessary to be able to switch to local scan mode for the pen 1 when the pen 1 is detected by partial global scan.

[0077] 11 and 12 are process flow diagrams showing a position detection method executed by control unit 28 to avoid such a situation. Hereinafter, the position detection method executed by control unit 28 according to this embodiment will be described in detail with reference to these figures.

[0078] 11 and 12 differ from the method shown in Figures 4 and 5 in that steps S60 to S62 are inserted between steps S2 and S3, and steps S63 to S67 are adopted instead of steps S41 to S44. The following description will focus on these differences.

[0079] 12, after executing step S13, the control unit 28 determines whether or not the current detection frequency is for the pen 1 (i.e., the resonance frequency of the position indicator 2a) (step S63). As a result, if it is determined that the current detection frequency is for the pen 1, the control unit 28 returns the process to step S11 and continues the local scan of the pen 1. On the other hand, if it is determined that the current detection frequency is not for the pen 1, the control unit 28 selects a coil for partial global scanning in the same manner as in step S42 shown in FIG. 5 (step S64), and then executes a partial global scan similar to step S43 shown in FIG. 5 (step S65). Note that the resonance frequency (specified frequency) used in the partial global scan of step S65 is the resonance frequency of the pen 1 (the frequency for the pen 1).

[0080] After executing the partial global scan, the control unit 28 determines whether or not pen 1 has been detected based on whether or not a reflected signal from pen 1 has been detected (step S66). If the control unit 28 determines that pen 1 has not been detected, it returns the process to step S11. This allows the eraser local scan mode to continue, allowing the user to continue inputting with the eraser. On the other hand, if the control unit 28 determines that pen 1 has been detected in step S66, it sets the pen 1 detection flag to True (step S67). Then, it returns the process to step S1a, initializes the detection frequency (step S1a), and re-enters the global scan mode (step S1b). This results in the Y-axis side global scan of step S2 being executed in the order of pen 2, pen 3, eraser, and pen 1.

[0081] 11, after step S2 is completed, the control unit 28 performs a process of determining whether the pen 1 detection flag is True (step S60). If the control unit 28 determines that the flag is True in step S60, it further performs a process of determining whether the current detection frequency is for pen 1 (step S61). If the control unit 28 obtains a negative determination result in step S61, it skips step S3 and proceeds to step S4. As a result, each process of the intermediate mode, including the determination process in step S8, is skipped. Therefore, even if the positions of pen 2, pen 3, or the eraser are detected in step S2, these positions are not ultimately detected, and a Y-axis side global scan is performed for the next position indicator 2. The determination result in step S61 is positive if a Y-axis side global scan for pen 1 is performed. In this case, step S3 is executed, and it is possible to proceed to the intermediate mode. Therefore, if pen 1 is detected by the partial global scan, it is possible to transition to the local scan mode for pen 1.

[0082] If the control unit 28 determines that the result in step S60 is False, it skips the processes of steps S61 and S62 and proceeds to step S3. As a result, if the pen 1 is not detected in the partial global scan, it is possible to transition to the intermediate mode as usual, regardless of the type of position indicator 2. If the control unit 28 obtains a positive determination result in step S61, it performs a process of setting the pen 1 detection flag to False (step S62) and then proceeds to step S3. In this way, the determination result of step S60 can be fixed to False until the next partial global scan for pen 1 is executed.

[0083] As described above, according to the position detection device 1 and position detection method of this embodiment, when the position of pen 1 is detected as a result of performing a partial global scan and the mode is switched to global scan mode, the positions of pen 2, pen 3, or the eraser are not detected, so it is possible to detect the position of pen 1 even though pen 1 is a non-priority position indicator. Therefore, it is possible to switch pen 1, which is a non-priority position indicator, to local scan mode by performing a partial global scan.

[0084] 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.

[0085] For example, in this embodiment, an example of a position detection method according to the present invention has been described using a position indicator 2a having a pen function and a position indicator 2b having an eraser function, but the present invention is widely applicable to a plurality of position indicators having different functions.

[0086] In addition, in this embodiment, the position indicator 2a having the pen function has been described as having a pen-like shape, and the position indicator 2b having the eraser function has been described as having an eraser-like shape. However, by providing a switch for switching between the pen function and the eraser function in the position indicator and controlling this switch, it is possible to realize both the pen function and the eraser function in a position indicator of the same shape.

[0087] Furthermore, for example, in this embodiment, global scans are performed in the order of Y-axis side global scan followed by X-axis side global scan (see Figure 4 and others), and local scans are performed in the order of X-axis side local global scan followed by Y-axis side local scan (see Figure 7(a)), but the present invention can also be preferably applied when one or both of these orders are reversed. [Explanation of symbols]

[0088] 1 Position detection device 2 Position indicator 2a Position indicator (pen 1) 2b Position indicator (eraser) 2c Position indicator (Pen 2, Pen 3) 3. Inductors 4 capacitors 5 Side Switch 10 sensors 10a Input surface 20 Sensor Controller 21 Selection circuit 22 Switch Circuit 23 Amplifier 24 Detector circuit 25 Low-pass filter 26 Sample and hold circuit 27 Analog-to-digital conversion circuit 28 Control Unit 29 Oscillators 30 Current Driver 40 Host Processor LC,X1~X m ,Y1~Y n Loop coil Pm Main peak position Ps Sidelobe position

Claims

1. A sensor, a controller that detects, via the sensor, a first position indicated by a first position indicator using a first frequency and a second position indicated by a second position indicator using a second frequency; The controller When the first position or the second position is detected and the process shifts to a local scan, which is a position detection in an area near the detected position, determining whether the frequency used in the local scan is the second frequency; when it is determined that the frequency used in the local scan is not the second frequency, alternately performing the local scan and position detection using the second frequency; the position detection using the second frequency is a partial global scan that is a part of a global scan that scans the entire sensor; A position detection device characterized by:

2. the controller performs the global scan when the second position indicator is detected by the execution of the partial global scan.

2. The position detection device according to claim 1.

3. The controller when the global scan has been executed, determining whether the global scan has been executed in response to the detection of the second position indicator by the execution of the partial global scan; when it is determined that the global scan has been executed in response to the detection of the second position indicator by the execution of the partial global scan, restricting transition to the local scan when the global scan is not being executed at the second frequency.

3. The position detection device according to claim 2.

4. A position detection method for detecting, via a sensor, a first position indicated by a first position indicator using a first frequency and a second position indicated by a second position indicator using a second frequency, the method comprising: When the first position or the second position is detected and the process shifts to a local scan, which is a position detection in an area near the detected position, determining whether the frequency used in the local scan is the second frequency; when it is determined that the frequency used in the local scan is not the second frequency, alternately performing the local scan and position detection using the second frequency; the position detection using the second frequency is a partial global scan that is a part of a global scan that scans the entire sensor; A position detection method comprising:

Images