JP7457067B2 - Controller that performs stylus detection operations - Google Patents

Description

The present invention relates to a stylus and a controller, and more particularly to a stylus and a controller used in a position detection system in which a liquid crystal display screen has a touch surface function.

In recent years, the use of electronic devices such as smartphones and tablet computers that have liquid crystal display screens with touch screen functions has become commonplace. This type of electronic equipment was initially realized by placing a transparent electrode for a touch sensor as a separate component on the display screen of a liquid crystal component, but in order to reduce the number of components and make it even thinner, In recent years, a technique has been used in which an electrode for a liquid crystal screen (common electrode or pixel electrode) is also used as a part of an electrode for a touch sensor. In the following, a type of electronic device in which a display screen electrode and an independent touch sensor electrode are arranged on the display screen is referred to as a "non-in-cell" type, and the display screen electrode is part of the touch sensor electrode. The type of electronic equipment used as an "in-cell" type is called an "in-cell" type.

Patent Document 1 discloses an example of an in-cell electronic device. In this example, one of a pair of electrodes constituting a mutual capacitance type touch sensor is also used as a common electrode of the liquid crystal display device.

Patent Document 2 also discloses an example of an in-cell type electronic device. The document describes that in an electronic device similar to Patent Document 1, a touch detection operation and a display operation are performed in a time-sharing manner for each display horizontal period, and that in the touch detection operation, different drive electrodes are used for each display horizontal period. It is stated that you can choose.

In addition, in recent years, active electrostatic styluses that are configured to be able to send and receive signals to and from position detection devices are increasingly being used as input devices for handwriting input on the touch surfaces of electronic devices. There is. Hereinafter, the active electrostatic stylus will be simply referred to as a "stylus." Furthermore, a signal transmitted from the stylus to the electronic device is referred to as a "downlink signal," and a signal transmitted from the electronic device to the stylus is referred to as an "uplink signal."

Patent Document 3 describes an example of a stylus configured to transmit an unmodulated continuous signal for position detection as well as a signal modulated by pen pressure information, a unique ID, or the like. Hereinafter, a position detection signal that has a predetermined pattern such as an unmodulated signal and does not include information will be referred to as a "position signal", and a signal modulated by pen pressure information or a unique ID will be referred to as a "data signal". It is called.

JP2009-244958A Japanese Patent Application Publication No. 2011-233018 International Publication No. 2015/111159

By the way, it would be convenient if the stylus as described above could be used in the above-mentioned non-in-cell type and in-cell type electronic devices as well. In this case, the touch sensor electrode is also used as a downlink signal receiving electrode and an uplink signal transmitting electrode.

However, in in-cell electronic devices, the electrodes for the LCD screen (common electrode and pixel electrode) and part of the electrode for the touch sensor are also used, so the electrode for the LCD screen has a potential for pixel driving. During the pixel drive operation in which the touch sensor is set, the part of the electrode for the touch sensor cannot be used for receiving a downlink signal or for transmitting an uplink signal. Due to this, various problems as shown below have arisen in making the stylus usable in non-in-cell type or in-cell type electronic equipment, and a solution has been required.

The first challenge is to configure a stylus so that it can be used in both non-in-cell and in-cell electronic devices. It would be convenient if the user could use one stylus with both non-in-cell electronic devices and in-cell electronic devices without having to change the stylus. In order to achieve this, it is necessary to configure the stylus so that the transmission of the downlink signal is paused while the pixel driving operation of the liquid crystal display device is being performed. However, this transmission suspension period is nothing but waste from the perspective of a non-in-cell type electronic device that can receive downlink signals even while performing a pixel driving operation. However, if the stylus is configured to transmit downlink signals even while pixel driving operations are in progress, unnecessary transmission pause periods from the perspective of non-in-cell electronic devices will be eliminated, but this time, in-cell When used in a type of electronic device, there may be a case where the electronic device fails to receive a downlink signal, resulting in a loss of transmitted information. As described above, it is difficult to simultaneously improve transmission efficiency when used with non-in-cell type electronic equipment and prevent loss of transmitted information when used with in-cell type electronic equipment, and as a result, until now, It has been considered difficult to construct a stylus for use in both non-in-cell and in-cell electronic devices.

The second challenge is to reduce the time it takes for the stylus to start transmitting downlink signals to an in-cell electronic device after detecting an uplink signal from the in-cell electronic device. In order to transmit a downlink signal to an in-cell electronic device, the stylus needs to know a period during which no pixel driving operation is performed in the electronic device (hereinafter referred to as a "blank period"). Therefore, if an electronic device sends an uplink signal to the stylus that includes information indicating how to arrange blank periods (interval, duration, etc.) as part of the negotiation operation performed at the start of communication, such an uplink signal is quite large, so it takes a long time before the stylus can start transmitting downlink signals. Therefore, there is a need to shorten this time.

The third issue is ensuring a high position detection execution rate when the stylus is used with in-cell electronic equipment. In an in-cell type electronic device, as described above, there is a period during which a downlink signal cannot be transmitted, so the frequency of transmitting the position signal described above must be reduced accordingly. As a result, the execution rate of position detection becomes low, so improvements are needed.

One of the objects of the present invention is to provide a stylus and a controller that can solve various problems that need to be solved in order to enable the stylus to be used in non-in-cell type or in-cell type electronic equipment, as described above. It is in.

A stylus according to a first aspect of the present invention is a stylus configured to be able to transmit data consisting of a K-bit (K>0) digital value to an electronic device, and the stylus has a coupling capacitance with a sensor electrode of the electronic device. A stylus electrode forming a Which mode to operate in: a first mode in which the data is transmitted using a first period, and a second mode in which the data is transmitted using N pieces of second period (N>M). and a signal processing circuit that repeatedly transmits the data according to the determined mode.

The stylus according to the second aspect of the invention is the stylus according to the first aspect, further comprising: the signal processing circuit including the command as one of the uplink signals when operating in the second mode. Transmission of the data is started in response to detection of a shortened synchronization signal, which is a signal with a shorter time length than the uplink signal.

The controller according to the third aspect of the present invention is configured to perform the stylus detection operation in each of N (N>1) second periods arranged within a display period that is one period of the display operation. A controller for a display device configured to transmit a second command for specifying data to be transmitted by the stylus using the second period after the stylus is detected by the detection operation. On the other hand, before the stylus is detected by the detection operation, a first command including type specifying information that specifies the type of the display device is sent once in one display cycle. The message is sent multiple times within the same period.

A stylus according to a fourth aspect of the present invention is a stylus used with a controller of a display device configured to perform a stylus detection operation during each of N (N>1) second periods arranged within a display cycle, which is one period of a display operation, and transmits a position signal in response to receiving a first command from the controller that includes type-specific information that identifies the type of the display device, and transmits a data signal including data specified by the second command in response to receiving a second command from the controller that specifies data to be transmitted using the second period.

A controller according to a fifth aspect of the present invention has first and second electrodes that intersect with each other, and supplies a voltage for pixel driving to the first electrode during the pixel driving period, while supplying a pixel driving voltage to the first electrode during the pixel driving period. A controller for an in-cell liquid crystal display device that detects the position of a stylus using the first and second electrodes during a different stylus detection period, the controller using the second electrode to detect the position of the stylus. transmitting a command requesting transmission of a downlink signal, and performing and detecting the downlink signal transmitted from the stylus in response to the command using both the first and second electrodes; The position of the stylus is detected based on the downlink signal.

According to the first aspect of the invention, when the type of electronic device indicated by the command is a non-in-cell type, the stylus uses a relatively small number of first periods to generate a K-bit digital value. On the other hand, if the type of electronic device indicated by the command is an in-cell type, a relatively large number of By transmitting data consisting of K-bit digital values (for example, pen pressure data) using the second period, it is possible to prevent transmission information from being lost due to reception failure in the electronic device. Therefore, it becomes possible to configure the stylus so that it can be used in both non-in-cell type electronic equipment and in-cell type electronic equipment.

According to the second aspect of the present invention, the stylus can know its arrival every second period by means of a simple shortened synchronization signal (for example, data for one spreading code). Therefore, it is no longer necessary to transmit an uplink signal containing information indicating the arrangement (interval, duration, etc.) of the blank period at the start of communication, so that after the stylus detects the uplink signal from the in-cell electronic device, It becomes possible to shorten the time required to start transmitting a downlink signal to the electronic device.

According to the third or fourth aspect of the present invention, the controller realizes an in-cell electronic device (that is, N controllers are arranged within a display period that is one period of display operation (N>1 controllers). ), the commands are transmitted at different frequencies before the stylus is detected and after the stylus is detected, and specifically sends commands less frequently (once in one display period) after the stylus is detected than before the stylus is detected, whereas before the stylus is detected, After the stylus is detected, the stylus sends a command specifying which communication protocol to use to send downlink signals more frequently than after the stylus is detected, so when the stylus is used with in-cell electronics. It becomes possible to shorten the response time of stylus detection before the stylus is detected, while ensuring the execution rate of position detection when the stylus is detected.

According to the fifth aspect of the present invention, the controller can send commands to the stylus even while using the first electrode for pixel driving. Therefore, it is possible to ensure the execution rate of position detection when the stylus is used with an in-cell type electronic device.

1 is a diagram illustrating how the position detection system according to the first embodiment of the present invention is used; FIG. 2 is a diagram showing a configuration of the stylus 2 shown in FIG. 1 . 2 is a diagram showing the configuration of a tablet 3B shown in FIG. 1. FIG. (a) is a schematic cross-sectional view showing the arrangement of sensor electrodes 30X, 30Y in tablet 3B, and (b) is a schematic top view corresponding to (a). (a) is a schematic cross-sectional view showing the arrangement of sensor electrodes 30X, 30Y on tablet 3A, and (b) is a schematic cross-sectional view showing the arrangement of sensor electrodes 30X, 30Y on tablet 3C. FIG. 3 is a diagram showing the configuration of an uplink signal US. It is a figure which shows the operation|movement of the controller 31 of the tablet 3B at the time of finger detection execution. FIG. 13 is a diagram showing the operation of the controller 31 of the tablet 3B when a display operation is executed. FIG. 13 is a diagram showing the operation of the controller 31 of the tablet 3B when transmitting an uplink signal. It is a figure which shows the operation|movement of the controller 31 of the tablet 3B at the time of a downlink signal reception. 2 is a state transition diagram of the stylus 2 shown in FIG. 1. FIG. 11 is a diagram showing details of the operation of the stylus 2 in state S103 (operation mode) shown in FIG. 10. FIG. (a) is a time chart of the respective operations when the stylus 2 and tablet 3A communicate with each other (when data is transmitted using M (M≧1) first periods S), and (b) is a time chart of the respective operations when the stylus 2 and tablet 3B communicate with each other (when data is transmitted using N (N>M) second periods T). 7 is a diagram showing the arrangement of signals within a second period T. FIG. 3A and 3B are diagrams showing how the second period T is used by the tablet 3B, in which (a) shows before the stylus 2 is detected, and (b) shows after the stylus 2 is detected. FIG. 7 is a diagram showing how to use the second period T by the stylus 2, (a) before being detected by the tablet 3B, (b) being detected by the tablet 3B and in the hover state, (c) ) respectively indicate a case where the tablet 3B is detected and is in a contact state. It is a process flow diagram of the process which tablet 3B performs. It is a process flow diagram of the process which tablet 3B performs. 3 is a processing flow diagram of processing performed by the stylus 2. FIG. 3 is a processing flow diagram of processing performed by the stylus 2. FIG. 3 is a processing flow diagram of processing performed by the stylus 2. FIG. FIG. 7 is a diagram showing the operation of the controller 31 of the tablet 3B according to the second embodiment of the present invention when driving pixels. 12 is a time chart of respective operations when the stylus 2 and tablet 3B communicate with each other according to the second embodiment of the present invention. 12 is a time chart of respective operations when the stylus 2 and tablet 3B communicate with each other according to the third embodiment of the present invention.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

FIG. 1 is a diagram showing an example of a usage state of a position detection system according to a first embodiment of the present invention. The position detection system according to this embodiment includes tablets 3A, 3B, and 3C and a stylus 2 shown in the figure.

The detailed configuration of tablets 3A to 3C will be described later, but tablets 3A and 3C are the non-in-cell type electronic devices (display devices) described above, and tablet 3B is the in-cell type electronic device (display device) described above. Each of tablets 3A to 3C is configured to be able to write pictures and characters using both the stylus 2 and the user's finger 4. In addition, both tablets 3A and 3B are configured to be able to send and receive signals in both directions with the stylus 2, and perform two-way communication with the stylus 2. Meanwhile, tablet 3C is configured to be able to receive downlink signals from the stylus 2, but does not have the ability to send uplink signals to the stylus 2, and instead receives signals sent unidirectionally from the stylus 2.

The stylus 2 is a multi-protocol stylus (triple stylus) that supports three protocols (communication protocols) for communication with each of the tablets 3A to 3C. The user can draw pictures on the tablets 3A to 3C by pressing the pen tip of the stylus 2 against the touch surface of any of the tablets 3A to 3C and moving the pen tip of the stylus 2 on the touch surface while maintaining this state. or write characters. Further, the user continues to use the stylus 2, which he has started using, by moving it back and forth between the tablets 3A to 3C without changing to another stylus.

FIG. 2 is a diagram showing the configuration of the stylus 2. As shown in FIG. As shown in the figure, the stylus 2 includes a stylus electrode 20, a signal processing circuit 21, an amplifying section 22, a power source 23, a writing pressure detecting section 24, and a switch 25.

The stylus electrode 20 is a conductor installed near the pen tip of the stylus 2, and receives the uplink signal US transmitted by the tablets 3A and 3B and supplies it to the signal processing circuit 21. It plays the role of sending the supplied downlink signal DS toward the tablets 3A to 3C.

The pen pressure detection unit 24 includes a pressure sensor that detects pressure (pen pressure) applied to the pen tip of the stylus 2 (not shown). The pen pressure detection unit 24 converts the pen pressure detected by the pressure sensor into pen pressure data P consisting of a digital value of K bits (K>0), and supplies the data to the signal processing circuit 21 .

The switch 25 is a switch provided on the surface (side surface or end surface) of the housing of the stylus 2, and is configured to be turned on and off by the user. Switch information SW indicating the on/off state of this switch 25 is supplied to the signal processing circuit 21 .

The power supply 23 is a functional unit that supplies operating power to each part of the stylus 2, and is, for example, a battery.

The signal processing circuit 21 and the amplifying section 22 perform reception processing on the uplink signal US supplied from the stylus electrode 20, and generate one of two types of downlink signals DS1 and DS2 based on the result. It has a function of supplying to the electrode 20.

Here, in this embodiment, the downlink signal DS1 is a downlink signal DS made up of a pulse train signal, and the downlink signal DS2 is a downlink signal DS made up of a sine wave signal. More specifically, the position signal that is the downlink signal DS1 is an unmodulated pulse train signal, and the data signal that is the downlink signal DS1 is a signal obtained by modulating the pulse train signal with pen pressure data P or the like. Further, the position signal that is the downlink signal DS2 is an unmodulated sine wave signal, and the data signal that is the downlink signal DS2 is a signal obtained by modulating the sine wave signal with pen pressure data P or the like. Each of the tablets 3A to 3C is configured to be able to receive only one of the downlink signals DS1 and DS2. Therefore, when starting communication with the tablets 3A to 3C, the signal processing circuit 21 of the stylus 2 detects the type of downlink signal DS that can be received by the tablet as the communication partner, and performs a downlink signal DS according to the detected type. It is configured to transmit a link signal DS.

Now, as shown in FIG. 2, the signal processing circuit 21 includes a control section 21a, a boost section 21b, an oscillation section 21c, and a switch section 21d.

The booster 21b is a circuit that boosts the DC voltage supplied from the power supply 23 to generate the DC voltage V1. In a specific example, the booster 21b is configured by a DC-DC converter or a charge pump circuit.

The oscillator 21c is a circuit that generates an unmodulated sine wave signal (carrier signal) that oscillates at a predetermined frequency by performing an oscillation operation based on the DC voltage supplied from the power supply 23. The amplification section 22 plays the role of generating an unmodulated sine wave signal v2 by amplifying the sine wave signal generated by the oscillation section 21c at a predetermined amplification factor. As shown in FIG. 2, the amplification section 22 is preferably configured with an amplification circuit including a transformer and a capacitor.

The switch section 21d is a switch element configured so that the common terminal c and any one of the terminals a, b, g, and r are connected. Terminal a is connected to the output end of the boosting section 21b, terminal b is connected to the output end of the amplification section 22, terminal g is connected to a power supply wiring to which ground potential is supplied, and terminal r is connected to the control section 21a through a buffer. The common terminal c is connected to the stylus electrode 20.

The control unit 21a is an IC that not only supplies a control signal Ctrl for controlling the switch unit 21d but also receives an uplink signal US, and is configured to operate with the power supplied from the power supply 23. In a specific example, the control unit 21a may be an ASIC or an MCU. The control unit 21a operates by executing programs stored in an internally provided ROM and RAM.

When transmitting the downlink signal DS1, the control unit 21a switches between a state in which the terminal a is connected to the common terminal c and a state in which the terminal g is connected to the common terminal c, according to the control signal Ctrl. A process of switching the section 21d is performed. More specifically, when transmitting a position signal using the downlink signal DS1, the control section 21a periodically controls switching of the switch section 21d between the above two states at a predetermined period. As a result, an unmodulated pulse train signal is output from the switch section 21d. Further, when transmitting a data signal using the downlink signal DS1, the control unit 21a switches between the above two states according to data Res (see FIG. 3) such as pen pressure data P and switch information SW. Controls switching of the section 21d. As a result, a pulse train signal modulated based on the data Res is output from the switch section 21d. Note that the data Res may include other information such as identification information of the stylus 2 that is stored in advance in the signal processing circuit 21.

When transmitting the downlink signal DS2, the control unit 21a switches between a state where the terminal b is connected to the common terminal c and a state where the terminal g is connected to the common terminal c using the control signal Ctrl. A process of switching the section 21d is performed. More specifically, when transmitting a position signal using the downlink signal DS2, the control section 21a fixes the switch section 21d to the terminal b side. As a result, an unmodulated sine wave signal v2 is output from the switch section 21d. Further, when transmitting a data signal using the downlink signal DS2, the control section 21a controls switching of the switch section 21d between the above two states according to the above-mentioned data Res. As a result, a sine wave signal modulated based on the data Res is output from the switch section 21d.

When receiving the uplink signal US, the control unit 21a fixes the switch unit 21d to the terminal r side using the control signal Ctrl. As a result, the charge appearing on the stylus electrode 20 is supplied to the receiving terminal of the control section 21a, so that the control section 21a receives the uplink signal US based on the thus supplied charge.

Figure 3 shows the configuration of tablet 3B. Below, the configuration of tablet 3B, which is an in-cell type, will be explained in detail with reference to the figure, but the configuration is basically the same for tablets 3A and 3C. However, since they are not exactly the same, the differences from tablet 3B will be explained one by one in the explanation of tablet 3B given below.

As shown in FIG. 3, the tablet 3B includes a sensor 30, a controller 31, and a host processor 32.

The sensor 30 includes a plurality of sensor electrodes 30X each extending in the Y direction and arranged at equal intervals in the X direction perpendicular to the Y direction, and a plurality of sensor electrodes 30X each extending in the X direction and arranged at equal intervals in the Y direction. It has a configuration in which a plurality of sensor electrodes 30Y are arranged in a matrix. The sensor 30 is configured to form a coupling capacitance with the stylus 2 by these sensor electrodes 30X, 30Y. Further, the sensor 30 is used to detect not only the stylus 2 but also the finger 4. Although an example is shown in which both the sensor electrodes 30Y and 30X are made of linear conductors, the sensor electrodes 30Y and 30X may be made of conductors of other shapes. For example, one of the sensor electrodes 30Y and 30X, such as an electrode having a shape as exemplified in Patent Document 1, is constituted by a plurality of rectangular conductors arranged two-dimensionally so that the two-dimensional coordinates of the stylus can be detected. It may also be a thing.

FIG. 4(a) is a schematic cross-sectional view showing the arrangement of sensor electrodes 30X and 30Y in tablet 3B, and FIG. 4(b) is a schematic top view corresponding to FIG. 4(a). In FIG. 4(a), the side far from the stylus 2 is shown at the bottom, and the side near the stylus 2 is shown at the top. This point also applies to FIGS. 5(a) and 5(b), which will be described later.

As shown in FIG. 4(a), the tablet 3B has a liquid crystal layer 60, a color filter glass 61, and a polarizing plate 62 as components of the liquid crystal display device, in order from the bottom, and the sensor electrodes 30Y, 30X are placed between these. More specifically, the sensor electrode 30X is formed on the top surface of the liquid crystal layer 60, and the sensor electrode 30Y is formed on the top surface of the color filter glass 61. Although not shown, transparent insulating layers are arranged between the sensor electrode 30X and the color filter glass 61 and between the sensor electrode 30Y and the polarizing plate 62, respectively.

A pixel electrode (not shown) for each pixel is formed under the liquid crystal layer 60. The host processor 32 performs a driving operation for each pixel by controlling the potential of the pixel electrode while supplying a predetermined pixel driving voltage Vcom (fixed value in this case) to each sensor electrode 30X. Since the pixel driving voltage Vcom is supplied in this manner, the sensor electrode 30X cannot be used for communicating with the stylus 2 or detecting the finger 4 while the pixel driving operation is being performed.

The plurality of sensor electrodes 30X and the plurality of sensor electrodes 30Y are arranged to intersect with each other, as shown in FIG. 4(b). Therefore, when viewing the tablet 3B from the touch surface side, the intersection of the sensor electrodes 30Y and 30X appears to be two-dimensionally arranged.

Here, the arrangement of the sensor electrodes 30X, 30Y in the tablets 3A, 3C will also be explained. FIG. 5(a) is a schematic cross-sectional view showing the arrangement of the sensor electrodes 30X, 30Y on the tablet 3A, and FIG. 5(b) is a schematic cross-sectional view showing the arrangement of the sensor electrodes 30X, 30Y on the tablet 3C. It is a diagram.

In the tablets 3A and 3C, a common electrode 63 is formed on the upper surface of the liquid crystal layer 60, as shown in FIGS. 5(a) and 5(b). Further, in the tablet 3A, the sensor electrodes 30X and 30Y are arranged as separate parts above the polarizing plate 62 from the liquid crystal display device, as shown in FIG. As shown in (b), it is arranged between a color filter glass 61 and a polarizing plate 62. Although tablets 3A and 3C are both non-in-cell types, the configuration of tablet 3A is sometimes referred to as an "out-sell" type, and the configuration of tablet 3C is sometimes referred to as an "on-sell" type.

In the tablets 3A and 3C, the above-mentioned pixel drive potential Vcom is supplied to the common electrode 63 independent of the sensor electrode, and is not supplied to the sensor electrode 30X. Therefore, in the tablets 3A and 3C, the sensor electrode 30X can be used for communicating with the stylus 2 or detecting the finger 4 even during execution of the pixel driving operation.

Returning to FIG. 3, the controller 31 is composed of an MCU 40, a logic unit 41, transmission units 42 and 43, a reception unit 44, and a selection unit 45.

The MCU 40 and the logic unit 41 are control units that control the transmitting and receiving operations of the controller 31 by controlling the transmitting units 42 and 43, the receiving unit 44, and the selecting unit 45. Specifically, the MCU 60 is a microprocessor that has an internal ROM and a RAM and operates by executing programs stored in these. The MCU 60 also has a function of outputting the pixel driving potential Vcom described above and a command COM described later. On the other hand, the logic unit 41 is configured to output control signals ctrl_1 to ctrl_4 and ctrl_r under the control of the MCU 40. Note that the function of outputting the pixel driving potential Vcom is provided in the host processor 32 in the tablets 3A and 3C, and is not provided in the MCU 40.

The transmitter 42 is a circuit that generates a finger detection signal FDS used to detect the finger 4 under the control of the MCU 40 . The finger detection signal FDS may be, for example, an unmodulated pulse train signal or a sine wave signal.

The transmitting unit 43 is a circuit that generates an uplink signal US under the control of the MCU 40 and the logic unit 41, and as shown in FIG. and a transmission guard section 54. Note that, in this embodiment, the pattern supply section 50 in particular will be described as being included in the transmitting section 43, but it may also be included in the MCU 40. Furthermore, the transmitter 43 is not provided in the controller 31 of the tablet 3C, which does not have the function of transmitting the uplink signal US.

Here, the configuration of the uplink signal US will be explained. Figure 6 is a diagram showing the configuration of the uplink signal US. As shown in the figure, the uplink signal US used in this embodiment is composed of a start bit SB consisting of 1 bit of information, and a command COM consisting of 5 bits of information. The command COM is composed of 4 bits of data CC0 to CC3 and 1 bit of cyclic redundancy code CRC calculated based on the data CC0 to CC3.

The start bit SB is used by the stylus 2 to detect the presence of the controller 31, and is known to the stylus 2 in advance (before the stylus 2 detects the controller 31). As will be described later, the stylus 2 detects the arrival of the uplink signal US by detecting this start bit SB. Additionally, the tablet 3B may transmit the start bit SB alone without transmitting a subsequent signal, and in the following, the uplink signal US in that case will be abbreviated as a shorter signal than the uplink signal US including the command COM. It may be called a synchronization signal PI.

Data CC0 to CC3 indicate commands for the stylus 2. There are two types of commands indicated by data CC0 to CC3.

The first command is a command that includes type identification information that specifies the type of communication protocol used between the stylus 2 and the tablet, and may be referred to as a "first command" below. The types of communication protocols mainly include the communication frequency (including rectangular wave or sine wave) for the stylus 2 to transmit the downlink signal DS (position signal or data signal), the format of the downlink signal DS (position signal This information distinguishes prior arrangements regarding the transmission time (timing and transmission period) of the downlink signal DS (including the type of data signal and the type of data transmitted using the data signal), and the transmission time (timing and transmission period) of the downlink signal DS. The first command is sent by tablets 3A, 3B that have not yet detected stylus 2. Note that the type identification information may be given to the stylus 2 as the type of tablet. The type identification information is, for example, information indicated by 1 bit of data CC0, and indicates whether the tablet that sent the command is of the tablet 3A or 3B, thereby determining the type of communication protocol required for the stylus 2. show.

Here, as will be described in detail later, when communicating with the tablet 3B, the stylus 2 executes the transmission of the downlink signal DS upon receiving the shortened synchronization signal PI. On the other hand, when communicating with the tablet 3A, the shortened synchronization signal PI is not used in the first place, and the stylus 2 executes the transmission of the downlink signal DS upon receiving the uplink signal US including the command COM. I will do it. Therefore, the type identification information can also be said to be information indicating whether the stylus 2 should transmit the downlink signal DS in response to the shortened synchronization signal PI.

The second command is a command that specifies data to be transmitted by the stylus 2, such as the pen pressure data P shown in FIG. 2, and may be referred to as a "second command" below. The second command is sent by the tablets 3A and 3B, which have already detected the stylus 2. In other words, the second command indicates that the controller 31 has detected the stylus 2.

Return to Figure 3. The pattern supply section 50 holds a start bit SB, and is configured to output the held start bit SB according to the instruction of the control signal ctrl_t1 supplied from the logic section 41. On the other hand, the command COM is supplied from the MCU 40 to the transmitter 43.

The switch 51 has a function of selecting either the pattern supply section 50 or the MCU 40 based on the control signal ctrl_t2 supplied from the logic section 61, and supplying the output of the selected one to the diffusion processing section 53. When the switch 51 selects the pattern supply section 50, the start bit SB is supplied to the spreading processing section 53. On the other hand, when the switch 51 selects the MCU 40, the command COM is supplied to the diffusion processing section 53.

The code sequence holding unit 52 has a function of generating and holding a spreading code PN of a predetermined chip length having autocorrelation characteristics based on a control signal ctrl_t3 supplied from the logic unit 41. The spreading code PN held by the code sequence holding unit 52 is supplied to the spreading processing unit 53.

The spreading processing unit 53 modulates the spreading code PN held by the code string holding unit 52 based on the value (start bit SB or command COM) supplied via the switch 51, thereby generating transmission chips of a predetermined chip length. Has the ability to retrieve columns. FIG. 6 shows an example of a transmission chip sequence obtained regarding the start bit SB. The spreading processing unit 53 is configured to supply the acquired transmission chip sequence to the transmission guard unit 54.

The transmission guard unit 54 is necessary for switching between the transmission operation and the reception operation between the transmission period of the uplink signal US and the reception period of the downlink signal DS based on the control signal ctrl_t4 supplied from the logic unit 41. It has a function to insert a guard period (a period in which neither transmission nor reception is performed).

The receiving unit 44 is a circuit for receiving the downlink signal DS transmitted by the stylus 2 or the finger detection signal FDS transmitted by the transmitting unit 42 based on the control signal ctrl_r of the logic unit 41. Specifically, it is configured to include an amplifier circuit 55, a detection circuit 56, and an analog-to-digital (AD) converter 57.

The amplifier circuit 55 amplifies and outputs the downlink signal DS or finger detection signal FDS supplied from the selection section 45. The detection circuit 56 is a circuit that generates a voltage corresponding to the level of the output signal of the amplifier circuit 55. The AD converter 57 is a circuit that generates a digital signal by sampling the voltage output from the detection circuit 56 at predetermined time intervals. The digital signal output from the AD converter 57 is supplied to the MCU 40. Based on the digital signal supplied in this way, the MCU 40 detects the position of the stylus 2 or finger 4 and acquires the data Res (the above-mentioned pen pressure data P, switch information SW, identification information, etc.) transmitted by the stylus 2. . The MCU 40 sequentially outputs the coordinates x, y indicating the acquired position and the acquired data Res to the host processor 32.

The selection unit 45 includes switches 58x and 58y and conductor selection circuits 59x and 59y.

The switch 58y is a switch element configured such that the common terminal is connected to either the T terminal or the R terminal. The common terminal of the switch 58y is connected to the conductor selection circuit 59y, the T terminal is connected to the output end of the transmitter 43, and the R terminal is connected to the input end of the receiver 44. Further, the switch 58x is a switch element configured such that the common terminal is connected to any one of the T1 terminal, the T2 terminal, the D terminal, and the R terminal. The common terminal of the switch 58x is connected to the conductor selection circuit 59x, the T1 terminal is connected to the output end of the transmitting section 43, the T2 terminal is connected to the output end of the transmitting section 42, and the D terminal outputs the pixel driving voltage Vcom. The R terminal is connected to the input end of the receiving section 44.

The conductor selection circuit 59x is a switching element for selectively connecting the plurality of sensor electrodes 30X to the common terminal of the switch 58x. The conductor selection circuit 58x is also configured to be able to simultaneously connect some or all of the plurality of sensor electrodes 30X to the common terminal of the switch 58x.

The conductor selection circuit 59y is a switching element for selectively connecting the plurality of sensor electrodes 30Y to the common terminal of the switch 58y. The conductor selection circuit 59y is also configured to be able to connect some or all of the plurality of sensor electrodes 30Y to the common terminal of the switch 58y at the same time.

The selection unit 45 is supplied with four control signals sTRx, sTRy, selX, and selY from the logic unit 41. Specifically, the control signal sTRx is supplied to the switch 58x, the control signal sTRy is supplied to the switch 58y, the control signal selX is supplied to the conductor selection circuit 59x, and the control signal selY is supplied to the conductor selection circuit 59y. The logic unit 41 controls the selection unit 45 using these control signals sTRx, sTRy, selX, and selY, thereby transmitting the uplink signal US or the finger detection signal FDS, applying the pixel driving voltage Vcom, and controlling the downlink signal US or the finger detection signal FDS. Reception of the link signal DS or the finger detection signal FDS is realized.

7 to 10 are diagrams showing the operation of the controller 31. Hereinafter, the relationship between the control state of the selection section 45 by the logic section 41 and the operation of the controller 31 will be explained in detail with reference to these figures as well as FIG. 3.

FIG. 7 is a diagram showing the operation of the controller 31 when performing finger detection. In this case, the logic unit 41 controls the switch 58x so that the T2 terminal is connected to the common terminal, and controls the switch 58y so that the R terminal is connected to the common terminal. Further, the conductor selection circuits 59x and 59y are controlled so that combinations of the plurality of sensor electrodes 30X and 30Y are selected in sequence. By doing so, the finger detection signal FDS that has passed through each of the plurality of intersections formed by the plurality of sensor electrodes 30X and 30Y is sequentially received by the reception unit 44. The MCU 40 detects the position of the finger 4 on the touch surface based on the reception strength of the finger detection signal FDS sequentially received in this way.

FIG. 8 is a diagram showing the operation of the controller 31 when executing a pixel driving operation. In this case, the logic unit 41 controls the switch 58x so that the D terminal is connected to the common terminal, and also controls the conductor selection circuit 59x so that all the plurality of sensor electrodes 30X are connected to the switch 58x at the same time. As a result, the pixel driving voltage Vcom is supplied from the MCU 40 to each sensor electrode 30X, so that the host processor 32 can execute the pixel driving operation. Note that the MCU 40 causes the logic unit 41 to execute the above control at a timing based on a timing signal supplied from the host processor 32.

FIG. 9 is a diagram showing the operation of the controller 31 when transmitting the uplink signal US. In this case, the logic unit 41 controls the switch 58x so that the T1 terminal is connected to the common terminal, and controls the switch 58y so that the T terminal is connected to the common terminal. Furthermore, the conductor selection circuits 59x and 59y are controlled so that all of the plurality of sensor electrodes 30X and 30Y are selected at the same time. As a result, the uplink signal US is transmitted from all of the plurality of sensor electrodes 30X and 30Y.

Here, the sensing range SR and uplink detection height AH shown by broken lines in FIG. 9 will be explained. First, the sensing range SR is a range in which the controller 31 can receive the downlink signal DS. In other words, in order for the controller 31 to receive the downlink signal DS transmitted by the stylus 2, the stylus 2 must be close to the touch surface of the tablet 3B to the extent that the downlink signal DS can reach the controller 31. . The sensing range SR indicates the range in which this downlink signal DS reaches the controller 31.

The uplink detection height AH indicates the limit of the height (distance from the touch surface) at which the stylus 2 can receive the uplink signal US. Generally, the uplink detection height AH is located at a location higher than the upper limit of the sensing range SR (a location away from the touch surface). This is due to the difference in transmission strength between the uplink signal US and the downlink signal DS. In the following, a state in which the stylus 2 is below the uplink detection height AH but not in contact with the touch surface is referred to as a "hover state," and a state in which the stylus 2 comes into contact with the touch surface is referred to as a "contact state." It is called.

FIG. 10 is a diagram showing the operation of the controller 31 when receiving the downlink signal DS. In this case, the logic unit 41 controls each of the switches 58x and 58y so that the R terminal is connected to the common terminal. The method of controlling the conductor selection circuits 59x and 59y differs depending on the type of downlink signal DS to be received.

That is, when receiving the downlink signal DS, which is a position signal, the logic unit 41 controls the conductor selection circuits 59x, 59y so that combinations of the multiple sensor electrodes 30X, 30Y are selected sequentially. In this way, the position signal that has passed through each of the multiple intersections formed by the multiple sensor electrodes 30X, 30Y is sequentially received by the receiver 44. The MCU 40 detects the position of the stylus 2 on the touch surface based on the reception strength of the position signals thus sequentially received.

On the other hand, when receiving the downlink signal DS, which is a data signal, the logic unit 41 selects a predetermined number of sensor electrodes that are located near the position of the stylus 2 detected by reception of the previous position signal, among the plurality of sensor electrodes 30X, 30Y. The conductor selection circuits 59x and 59y are controlled so that only one book (for example, one book) is selected. Data signals received by the selected predetermined number of sensor electrodes are supplied to the MCU 40 via the receiving section 44. The MCU 40 acquires the above-mentioned data Res from the data signal supplied in this way.

The configurations of the stylus 2 and tablets 3A to 3C have been described above. Next, the operation of the stylus 2 will be explained in more detail.

FIG. 11 is a state transition diagram of the stylus 2. Further, FIG. 12 is a diagram showing details of the operation of the stylus 2 in state S103 (operation mode) shown in FIG. 11.

As shown in FIG. 11, the initial state of the stylus 2 is the sleep mode (state S100). In the sleep mode, the stylus 2 does not perform any special processing other than periodically transitioning to a state in which it detects the uplink signal US and pen pressure (state S101).

The stylus 2 in state S101 detects the uplink signal US and the writing pressure. Specifically, first, it detects the start bit SB that constitutes the first bit of the uplink signal US. Then, when the start bit SB is detected, it also detects the type-specific information described above. In parallel with these detection operations, it also determines whether the writing pressure data P output by the writing pressure detection unit 24 is 0 or not.

If neither the start bit SB nor the pen pressure is detected by the detection operation performed in state S101, or if the type identification information is not detected even if the start bit SB is detected, the stylus 2 continues to use the uplink signal US until a timeout occurs. and repeat the pen pressure detection operation. After the timeout, the process returns to state S100 and enters sleep mode.

On the other hand, if the start bit SB and type identification information are detected, or if pen pressure is detected, the stylus 2 transitions to a state where communication protocol selection is performed (state S102). For example, in the case of a communication protocol for communicating with the tablet 3B, it includes a method of using the second period T (see FIG. 16), which will be described later.

As shown in FIG. 12, when the start bit SB is detected and the type of tablet indicated by the type identification information is tablet 3A, stylus 2 selects a communication protocol for communicating with tablet 3A. . In addition, if the start bit SB is detected and the type of tablet indicated by the type identification information is an in-cell tablet 3B, a communication protocol for communicating with the tablet 3B is selected, and the start bit SB is detected. When the pen pressure is detected in a state where the pen pressure data P is not 0 (that is, when the pen pressure data P is not 0), a communication protocol for communicating with the tablet 3C is selected.

The stylus 2 that has selected the communication protocol in state S102 transitions to the operation mode (state S103), as shown in FIG. The operation mode is a mode in which communication is performed according to the selected communication protocol, and as shown in FIG. 12, it is configured to include three states S103a to S103c in detail.

State S103a is a mode in which the stylus 2 communicates with the tablet 3A according to the communication protocol for communicating with the tablet 3A (data is transmitted using M first periods S (M≧1), which will be described later). (first mode). In this case, the stylus 2 repeats the operation of receiving the uplink signal US including the command COM (state S111) and transmitting the downlink signal DS in accordance with the received command COM (state S112). The downlink signal DS transmitted in state S112 is composed of only a position signal when the command COM indicates the above-mentioned first command, and when the command COM indicates the above-mentioned second command. , a position signal, and a data signal containing data specified by the command COM.

State S103b is a mode in which the stylus 2 communicates with the tablet 3B according to the communication protocol for communicating with the tablet 3B (data is transmitted using N pieces (N>M) of second periods T, which will be described later). The second mode is In this case, the stylus 2 first performs an operation of receiving the uplink signal US including the command COM (state S113). The stylus 2 that has received the command COM in state S113 prepares to transmit a position signal if the command COM indicates the first command. On the other hand, if the received command COM indicates the second command, it prepares to transmit a position signal, acquires the data specified by the command COM, and prepares to transmit a data signal including the acquired data. conduct.

Subsequently, the stylus 2 performs an operation of receiving the shortened synchronization signal PI (state S114). As described above, the shortened synchronization signal PI is an uplink signal US consisting only of the start bit SB and has a shorter time length than the uplink signal US including the command COM. Since the shortened synchronization signal PI is a signal with a shorter time length than the uplink signal US including the command COM, the stylus 2 detects that the detected uplink signal US is a shortened synchronization signal depending on the time length of the detected uplink signal US. It is possible to determine which of the signals includes the signal PI and the command COM.

When the shortened synchronization signal PI is received, the stylus 2 transmits part of the prepared position signal or data signal in response to the shortened synchronization signal PI (state S115). Since the stylus 2 can only transmit one bit of information in response to the shortened synchronization signal PI, the tablet 3B is configured to repeatedly transmit the shortened synchronization signal PI, and the stylus 2 transmits the shortened synchronization signal PI each time it receives the shortened synchronization signal PI. , configured to transmit a portion of a position signal or a data signal. After the transmission of all bits of the data signal is completed, the stylus 2 returns to state S113 and repeats the operation of receiving the uplink signal US including the command COM. These points will be explained in more detail later.

State S103c is a mode in which the stylus 2 transmits a one-way downlink signal DS to the tablet 3C according to a communication protocol for communicating with the tablet 3C. In this case, the stylus 2 unilaterally repeats transmission of the downlink signal DS (state S116).

Return to FIG. 11. When a predetermined timeout state occurs in operation mode S103, the stylus 2 transitions to a timeout state (state S104). This timeout condition occurs when the start bit SB is not received for a predetermined period of time with respect to communication with tablets 3A, 3B. On the other hand, communication with the tablet 3C occurs when pen pressure is no longer detected. The stylus 2 that has transitioned to the timeout state returns to state S101 and repeats the uplink signal US and writing pressure detection operation.

The state transition of the stylus 2 has been described above. Next, these operations when the stylus 2 and each of the tablets 3A and 3B communicate will be described in more detail with reference to a time chart.

FIG. 13(a) is a time chart of each operation when the stylus 2 and tablet 3A communicate, and FIG. 13(b) is a time chart of each operation when the stylus 2 and tablet 3B communicate. This is a time chart. Note that the video synchronization signal Vsync shown in FIGS. 13A and 13B is a pulse signal that indicates the operation cycle VT of video display by the host processor 32 (display cycle that is one cycle of display operation). The host processor 32 is configured to perform the display of one image frame during one operating cycle VT.

First, as shown in FIG. 13A, the controller 31 of the tablet 3A basically performs an uplink signal US transmission operation, a downlink signal DS reception operation, and a finger detection operation in one operation cycle VT. are configured to be executed repeatedly in this order. The period during which the downlink signal DS reception operation is performed is hereinafter referred to as a first period S. Assuming that the number of first periods S provided after the transmission of the uplink signal US is M (M≧1), M=1 in the example of FIG. 13(a), but the data amount of the downlink signal DS is M≧2 may be used, such as when the downlink signal DS cannot be fully received in one reception operation considering the required execution cycle of the finger detection operation. In this case, a finger detection operation will be arranged during each first period S. Note that the start timing of one or more first periods S that are set after the transmission period of the uplink signal US may be determined in advance by the communication protocol, or the start timing of the one or more first periods S that is set after the transmission period of the uplink signal US may be determined in advance by the communication protocol, or the start timing of the first period S that is set after the transmission period of the uplink signal 2 may be notified.

After the stylus 2 that communicates with the tablet 3A receives the command COM through the uplink signal US reception operation, the stylus 2 receives the selected communication protocol or one or more first periods from the uplink signal US in state S102 of FIG. The arrangement of S is acquired, and the acquired first period S is used to transmit the downlink signal DS in accordance with the received command COM. Specifically, a position signal is first transmitted, and then a data signal including data instructed by the command COM is transmitted. The tablet 3A that receives this downlink signal DS first detects the position of the stylus 2 based on the position signal, and then uses one or more sensor electrodes near the detected position to receive the data signal. conduct.

Next, as for tablet 3B, as shown in FIG. 13(b), multiple horizontal retrace periods HB are arranged within one operation cycle VT. In the latter half of the horizontal retrace period HB, a process is performed to return the pixels to be driven from the right end of the screen to the left end, and during this process, the host processor 32 pauses the pixel drive process. The period during which the pixel drive process is paused in this manner is generally called a blank period BP, and tablet 3B uses this blank period BP as a second period T for communicating with the stylus 2 or detecting the finger 4. The second period T is a period shorter than the first period S, and if the number of second periods T provided within one operation cycle VT is N, N is a number greater than the above-mentioned M (N>M). In the example of FIG. 13(b), N=40 (second periods T1 to T40), but N does not have to be 40.

FIG. 14 is a diagram showing the arrangement of signals within the second period T. As shown in the figure, the controller 31 of the tablet 3B transmits the start bit SB as the shortened synchronization signal PI in synchronization with the start timing of the second period T. Then, the stylus 2 transmits a downlink signal DS (position signal or data signal) in response to receiving the shortened synchronization signal PI. When transmitting a data signal, the amount of data that can be transmitted within one second period T is 1 bit, as described above.

FIG. 15 is a diagram showing a specific method of using the second period T by the tablet 3B. FIG. 15(a) shows the state before the stylus 2 is detected, and FIG. 15(b) shows the state after the stylus 2 is detected.

As shown in FIG. 15(a), the tablet 3B before detecting the stylus 2 transmits the second period T a plurality of times (for example, In each of the two second periods T1 and T21), the uplink signal US including the command COM is transmitted. The command COM in this case indicates the first command and includes type identification information that identifies the type of tablet. Further, the tablet 3B in this case performs the detection operation of the stylus 2 and the finger 4 by using each of the other second periods T in a time-sharing manner.

On the other hand, after detecting the stylus 2, the tablet 3B transmits the command COM a smaller number of times than the number of times it transmits the command COM before detecting the stylus 2 (for example, one (only during period T1) transmits the uplink signal US including the command COM. The command COM in this case indicates the second command, and specifies the data (pen pressure data P, etc.) that the stylus 2 should transmit using the second period T. The tablet 3B then detects the position of the stylus 2 using each of the ten second periods T2, T5, T9, T13, T17, T21, T25, T29, T33, T37 (stylus detection periods), 20 second periods T3, T6, T7, T10, T11, T14, T15, T18, T19, T22, T23, T26, T27, T30, T31, T34, T35, T38, T39, T40 (data signal reception The data signal is received using each of the nine second periods T4, T8, T12, T16, T20, T24, T28, T32, and T36 (finger detection periods). The position of finger 4 is detected.

FIG. 16 is a diagram showing a specific method of using the second period T by the stylus 2. 16(a) is before being detected by the tablet 3B, FIG. 16(b) is being detected by the tablet 3B and in the hover state, and FIG. 16(c) is being detected by the tablet 3B and When in contact, the following are shown.

As described above, the command COM sent by the tablet 3B that has not yet detected the stylus 2 indicates the first command that includes type identification information that identifies the type of tablet. When the stylus 2 detects the uplink signal US including this command COM and understands that the transmission source of the uplink signal US is the tablet 3B from the type identification information included therein, it refers to FIGS. 11 and 12. As described above, the communication protocol used for communication with the tablet 3B is selected, and position signals are continuously transmitted as shown in FIG. 16(a). Note that although only the second period T is shown in FIG. 16(a), this continuous transmission is the time between two adjacent second periods T (the time during which the pixel driving operation is performed). will continue to be executed.

The command COM transmitted by the tablet 3B that has detected the stylus 2 indicates the second command that specifies the data to be transmitted by the stylus 2, such as the pen pressure data P, as described above. Upon receiving this command COM, the stylus 2 performs different operations depending on whether it is hovering or touching. That is, as shown in FIG. 16(b), the stylus 2 during hovering uses the second periods T6 and T7 to sequentially transmit the second bit SW2 to the first bit SW1 of the switch information SW. , predetermined bits "1" and "0" are transmitted alternately. On the other hand, the stylus 2 at the time of contact transmits a predetermined bit "0" using the second period T3, and the second period T6, T7, T10, T11, T14 , T15, T18, T19, T22, T23, T26, T27, T30, and T31 to sequentially transmit the 14th bit P13 to the 1st bit P0 of the pen pressure data P, and transmit the second period T34 and T35. The second bit SW2 to the first bit SW1 of the switch information SW are transmitted in order, and the second period T38 to T40 is used to transmit the third bit of the checksum generated by the stylus 2 based on the transmitted data. The bits from Sum2 to the first bit Sum0 are transmitted in order.

In this way, the system related to the stylus 2 and tablet 3B of the present invention has two operating modes: hover and contact after the tablet 3B detects the stylus 2, as well as an operating mode before the stylus 2 is detected. including. In each of the three operating modes, the stylus 2 responds to its own state (whether it is hovering or contacting) and whether or not it has already been detected by the tablet 3B. , transmit position signals or data signals in accordance with the formats shown in FIGS. 16(b), 16(c), and 16(a), respectively.

Next, with reference to the processing flows of the tablet 3B and the stylus 2, the processing performed by each will be described in more detail.

FIGS. 17 and 18 are process flow diagrams of processes performed by the tablet 3B. However, the figure only shows the processing related to the stylus 2, and omits the illustration of the processing related to detecting the finger 4, for example.

<Operation before stylus detection>
FIG. 17 is a process flow diagram before the tablet 3B detects the stylus 2. As shown in FIG. 15, the tablet 3B first transmits the command COM indicating the first command (the command to be transmitted before the stylus 2 is detected) (specifically, at the timing shown in FIG. 15(a)) Wait for the arrival of the second period T1, T21) shown in FIG. The uplink signal US including the command COM indicating the command No. 1 is transmitted (step S2).

Subsequently, the tablet 3B scans all the sensor electrodes 30X and 30Y using the subsequent second period T (step S3). Note that since there is no need to specify the position of the stylus 2 here, only all the sensor electrodes 30Y may be scanned to shorten the scanning time. By doing so, it becomes possible to perform the detection operation of the finger 4 in a time-sharing manner within the same second period T over a longer period of time.

Next, the tablet 3B determines whether or not a position signal is detected as a result of the scan in step S3 (step S4). As a result, if it is determined that no detection has been made, the process returns to step S1 and continues.

<Operation after stylus detection>
FIG. 18 is a process flow diagram after the tablet 3B detects the stylus 2. As a result of the scan in step S3, if it is determined that a position signal has been detected, the tablet 3B determines the transmission timing (specific In this case, the stylus 2 waits for the arrival of the second period T1) shown in FIG. The uplink signal US including the command COM is transmitted (step S6).

Thereafter, as shown in FIG. 18, the tablet 3B sends the command COM indicating the second command (the command to be sent after detecting the stylus 2) at the transmission timing (second period T1 shown in FIG. 15(b)). ), the timing to detect the position of the stylus 2 (such as the second period T2 shown in FIG. 15(b)), and the timing to receive the data signal from the stylus 2 (such as the second period T3 shown in FIG. 15(b)). etc.) is waited for (step S7).

If, as a result of waiting, the timing for transmitting the command COM indicating the second command arrives, tablet 3B transmits an uplink signal US including the command COM indicating the second command (step S8).

When the time to detect the position of the stylus 2 arrives, the tablet 3B first transmits an abbreviated synchronization signal PI (start bit SB) (step S9), and then sequentially scans all the sensor electrodes 30X and 30Y (step S10). Then, it is determined whether or not a position signal has been detected by this scan (step S11), and if it is determined that a position signal has been detected, the position of the stylus 2 is identified based on the position of the sensor electrode that detected the position signal (step S12). On the other hand, if it is determined that the position signal has not been detected, the tablet 3B determines that the stylus 2 has left the tablet 3B, and returns the process to step S1. Note that here, the process is returned to step S1 in response to the failure to detect the position signal once, but it may be possible to return the process to step S1 only if the position signal has not been detected a predetermined number of times in succession.

When the timing to receive the data signal from the stylus 2 has arrived, the tablet 3B first transmits a shortened synchronization signal PI (start bit SB) (step S13), and then selects the sensor electrode identified immediately before among all the sensor electrodes 30X and 30Y. Only one or more sensor electrodes near the position of the stylus 2 are scanned (step S14). Then, it is determined whether or not a data signal has been detected through this scan (step S15), and if it is determined that a data signal has been detected, the data transmitted by the stylus 2 is obtained by extracting data from the data signal. (Step S16). On the other hand, if it is determined that the stylus 2 has not been detected, the tablet 3B determines that the stylus 2 has left the tablet 3B, and returns the process to step S1. Note that here, the process is returned to step S1 in response to the fact that the data signal is not detected once, but similarly to step S11, the process is returned to step S1 only when the data signal is not detected a predetermined number of times in succession. It is also possible to return it. Alternatively, the process may be returned to step S1 when the sum of the number of consecutive non-detections of the data signal and the number of consecutive non-detections of the position signal reaches a predetermined number of times.

Figures 19 to 21 are processing flow diagrams of the processing performed by stylus 2.

<Before detection of tablet 3A or 3B>
As shown in Fig. 19, the stylus 2 first executes a receiving operation (step S21), and then determines whether or not a start bit SB has been detected as a result of the receiving operation (step S22).

If it is determined in step S22 that the start bit SB is not detected, the stylus 2 subsequently determines whether the writing pressure is 0 (step S24). As a result, if it is determined that the pen pressure is 0, the process returns to step S21, whereas if it is determined that the pen pressure is not 0, a position signal and a data signal are transmitted (step S25). This corresponds to communication with the tablet 3C, which does not have an uplink signal US transmission function. The stylus 2 repeats step S25 and repeatedly determines whether the pen pressure has become 0 (step S26), and when it is determined that the pen pressure has become 0, it terminates communication with the tablet 3C and returns to step S21. Return to

If it is determined in step S22 that the start bit SB has been detected, the stylus 2 subsequently determines whether type identification information has been detected (step S27). The case where the type identification information is not detected is usually the case where the received start bit SB is the shortened synchronization signal PI, and in that case, the stylus 2 returns the process to step S21 (step S27). negative judgment). On the other hand, if the type identification information indicates that the tablet 3A is a non-in-cell tablet, the stylus 2 starts communicating with the tablet 3A according to the communication protocol with a non-in-cell tablet (FIG. 20). Similarly, when the type identification information indicates that the tablet 3B is an in-cell type tablet, the stylus 2 starts communicating with the tablet 3B according to the communication protocol with the in-cell type tablet (FIG. 21).

<When tablet 3A is detected>
FIG. 20 is a processing flow diagram of the stylus 2 when the stylus 2 detects the tablet 3A. As shown in the figure, the stylus 2 that has started communicating with the tablet 3A first continuously transmits a position signal over a predetermined period of time (step S30). Subsequently, the receiving operation is performed and an attempt is made to receive the uplink signal US including the command COM (step S31). As a result, it is determined whether the command COM has been received (step S32), and if it is determined that the command COM has not been received, the communication with the tablet 3A is ended and the process returns to step S21. On the other hand, if it is determined that the command COM has been received, it is determined whether the command COM indicates the second command (step S33).

If it is determined that the received command COM indicates the second command, the stylus 2 transmits the position signal and the data signal (step S34), and when finished, returns to step S31 and repeats the receiving operation. This repeats the process in which the stylus 2 transmits a position signal and a data signal each time the tablet 3A transmits the second command.

On the other hand, the stylus 2 that has determined that the received command COM does not indicate the second command returns to step S30 and continuously transmits position signals in order to inform the tablet 3A of its presence.

<When tablet 3B is detected>
FIG. 21 is a processing flow diagram of the stylus 2 when the stylus 2 detects the tablet 3B. The stylus 2 that has started communicating with the tablet 3B first continuously transmits position signals as shown in the figure (step S40). This continuous transmission is repeated until the reception timing of the uplink signal US including the command COM (specifically, the second period T1, T21 shown in FIG. 16) arrives (step S41).

If it is determined in step S41 that the timing to receive the uplink signal US including the command COM has arrived, the stylus 2 performs a receiving operation and attempts to receive the uplink signal US including the command COM (step S42). As a result, it is determined whether or not the command COM has been received (step S43), and if it is determined that the command COM has not been received, the communication with the tablet 3B is ended and the process returns to step S21. On the other hand, if it is determined that the command COM has been received, it is determined whether the command COM indicates the second command (step S44).

Having determined that the received command COM does not indicate the second command, the stylus 2 returns to step S40 and continuously transmits position signals in order to inform the tablet 3B of its presence.

On the other hand, the stylus 2 that has determined that the received command COM indicates the second command acquires the transmission data specified by the command COM (step S45). Then, the reception operation is executed again (step S46), and it is determined whether the start bit SB is detected (step S47). As a result, if it is determined that the start bit SB has been detected, it is further determined whether or not the command COM has been received following the start bit SB (step S48), and if it is determined that the command COM has been received, it is determined in step S45. The process returns to , and acquires the transmission data specified by the new command COM again. On the other hand, if it is determined that the command COM has not been received, the position signal or data is transmitted according to the assignment of the transmission content to each second period T shown in FIG. A signal is transmitted (step S46). Then, the process returns to step S46 and waits again for reception of the start bit SB.

If it is determined in step S47 that the start bit SB has not been detected, the stylus 2 further determines whether a predetermined time has elapsed since the last start bit SB was received (step S50). If it is determined that the elapsed time has elapsed (that is, if the uplink signal US is not detected for a predetermined period of time), the communication with the tablet 3B is terminated and the process returns to step S21. On the other hand, if it is determined that the time has not elapsed, the process returns to step S46 and the start bit SB reception operation is performed again.

As described above, according to the present embodiment, the stylus 2 indicates that the type of the tablet transmitting the uplink signal US is a non-in-cell type based on the type of communication protocol indicated by the command COM. (in the case of the tablet 3A), data transmission efficiency can be improved by transmitting data such as pen pressure data P using a relatively small number of first periods S. On the other hand, if the type of communication protocol indicated by the command COM indicates that the type of tablet transmitting the uplink signal US is an in-cell type (if it is a tablet 3B), a relatively large number of By transmitting data such as the pen pressure data P using the second period T, it is possible to prevent the transmission information from being lost due to reception failure at the tablet 3B. Therefore, it is possible to configure the stylus 2 so that it can be used with both the non-in-cell tablet 3A and the in-cell tablet 3B.

The stylus 2 can also know the arrival (time of each blank period BP) of each second period T by a simple abbreviated synchronization signal called the abbreviated synchronization signal PI (start bit SB). Therefore, when starting communication between the stylus 2 and the tablet 3B, it is no longer necessary to transmit an uplink signal US including information indicating the arrangement (interval, duration, etc.) of the blank periods BP, so it is possible to shorten the time it takes for the stylus 2 to start transmitting a downlink signal DS to the tablet 3B after detecting an uplink signal US from the in-cell tablet 3B.

In addition, since the controller 31 of the tablet 3B is configured to transmit the command COM only once in one operation cycle VT after the stylus 2 is detected, the position of the stylus 2 when used together with the tablet 3B is It becomes possible to secure the execution rate of detection.

Figure 22 is a diagram showing the operation of the controller 31 of the tablet 3B according to the second embodiment of the present invention when driving pixels. As can be seen by comparing this figure with Figure 8, the controller 31 according to this embodiment differs from the first embodiment in that the sensor electrode 30Y is used as a transmission electrode even during the period when the pixel is driven (pixel driving period), but is otherwise similar to the first embodiment. Below, this embodiment will be described in detail, focusing on the differences from the first embodiment.

FIG. 23 is a time chart of the respective operations when the stylus 2 and tablet 3B communicate with each other according to the present embodiment. As shown in the figure, the controller 31 (see FIG. 3) of the tablet 3B according to the present embodiment controls the sensor voltage during the pixel drive period in which the pixel drive voltage Vcom is supplied to the sensor electrode 30X (first electrode). The electrode 30Y (second electrode) is used to transmit an uplink signal US including a command COM and a shortened synchronization signal PI. That is, the controller 31 of the tablet 3B according to the present embodiment transmits the uplink signal US by effectively utilizing the vacant time of the sensor electrode 30Y that occurred in the first embodiment.

According to this embodiment, since the transmission and reception of the command COM is performed outside the second period T, it becomes possible to also use the second period T1 for the transmission and reception of the downlink signal DS. Therefore, when the second period T1 is used, for example, for transmitting and receiving position signals, it is possible to improve the execution rate of position detection of the stylus 2 compared to the first embodiment. Further, when the second period T1 is used for transmitting and receiving data signals, it is possible to increase the amount of data signals transmitted by the stylus 2 compared to the first embodiment. Furthermore, when the second period T1 is used to detect the position of the finger 4, it is possible to improve the execution rate of position detection of the finger 4 compared to the first embodiment.

Furthermore, according to the present embodiment, since the transmission and reception of the shortened synchronization signal PI is performed outside the second period T, the entire second period T is used to transmit and receive the downlink signal DS. It becomes possible to do so. Therefore, it is possible to transmit, for example, 2 bits of data within one second period T, so the amount of data of the data signal transmitted by the stylus 2 is increased compared to the first embodiment. becomes possible. Furthermore, when maintaining the data amount of the data signal, the transmission frequency of the data signal can be lowered, so the execution rate of position detection of the stylus 2 or finger 4 can be improved compared to the first embodiment. becomes possible.

FIG. 24 is a time chart of the respective operations when the stylus 2 and tablet 3B communicate with each other according to the third embodiment of the present invention. The figure shows the operation before the tablet 3B detects the stylus 2.

As described above, in the first embodiment, the tablet 3B before detecting the stylus 2 performs the detection operation of the stylus 2 and the detection operation of the finger 4 in each second period T in a time-sharing manner. was. This also applies to the second embodiment. In contrast, the tablet 3B according to the present embodiment performs only the finger 4 detection operation in each second period T, and the stylus 2 detection operation is performed outside the second period T. This embodiment is similar to the second embodiment in other respects, and therefore will be described in detail below, focusing on the differences from the second embodiment.

As shown in FIG. 24, the controller 31 of the tablet 3B according to the present embodiment transmits the uplink signal US including the command COM before the start of the second period T1, and then transmits the uplink signal US during each second period T1. Taking advantage of the time, the operation of receiving the position signal transmitted by the stylus 2 is performed using only the sensor electrode 30Y. Since only the sensor electrode 30Y is used, the position of the stylus 2 cannot be detected, but the presence of the stylus 2 can be detected. After detecting the presence of the stylus 2, the controller 31 receives a downlink signal DS including a position signal using both sensor electrodes 30X, 30Y during a second period T, as shown in FIG. 23, for example. By doing this, the position of the stylus 2 can be detected.

In FIG. 24, the position signal is received before the start of the second period T1, but if there is not enough time, this reception may be omitted. Also, although not shown in FIG. 24, the controller 31 of the tablet 3B in this embodiment transmits the command COM between the second periods T20 and T21, which was transmitted during the second period T21 in the first embodiment, and the reception during this period may also be omitted.

According to the present embodiment, it is possible to secure a longer time for detecting the position of the finger 4 before the tablet 3B detects the stylus 2 than in the first embodiment.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and the present invention may be implemented in various forms without departing from the gist thereof. Of course.

For example, in the above embodiment, as shown in steps S9 to S12 in FIG. 18, the position detection of the stylus 2 is performed every second period T, but the second period T is short and all sensor If scanning of 30X and 30Y is not possible, multiple second periods T (for example, all the second periods T used for receiving position signals within one operation cycle VT) 2 period T) may be used. The same applies to the detection of the finger 4.

In addition, in the above embodiment, it has been described that the data signal and the position signal are transmitted with different times, but in cases where it is not necessary to transmit the position signal, such as when the tablet can also identify the position of the stylus 2 based on the data signal, the transmission time of the position signal may be replaced with the transmission time of the data signal.

In addition, although the above embodiment has been described using a liquid crystal display device as an example, other display devices (such as organic EL, ) is also applicable to the present invention.

Furthermore, as the stylus 2, a triple stylus that supports three communication protocols used with the tablet 3A, tablet 3B, and tablet 3C has been described. It may be something that works.

In addition, the stylus 2 has an input section such as a switch that accepts an operation from the user in place of the function of receiving the uplink signal US, and receives the uplink signal US when the input section is operated. Alternatively, a configuration may be adopted in which communication protocols for tablet 3A, tablet 3B, and tablet 3C are switched.

2 Stylus 3A to 3C Tablet 4 Finger 20 Stylus electrode 21 Signal processing circuit 21a Control unit 21b Boosting unit 21c Oscillator 21d Switch unit 22 Amplifying unit 23 Power supply 24 Pen pressure detection unit 25 Switch 30 Sensors 30X, 30Y Sensor electrode 31 Controller 32 Host Processor 41 Logic section 42, 43 Transmission section 44 Receiving section 45 Selection section 50 Pattern supply section 51 Switch 52 Code string holding section 53 Spreading processing section 54 Transmission guard section 55 Amplification circuit 56 Detection circuit 57 Analog-to-digital converter 58x, 58y Switch 59x , 59y Conductor selection circuit 60 Liquid crystal layer 61 Color filter glass 61 Logic section 62 Polarizing plate 63 Common electrode AH Uplink detection height BP Blank period COM Command CRC Cyclic redundancy code DS, DS1, DS2 Downlink signal FDS Finger detection signal HB Horizontal retrace period P Pen pressure data PI Short synchronization signal Res Data S First period SB Start bit SR Sensing range SW Switch information T, T1 to T40 Second period (blank period)
US Uplink signal Vcom Pixel drive voltage Vsync Video synchronization signal VT Operation cycle

Claims (4)

A controller for detecting a position of a stylus using a first electrode and a second electrode disposed so as to intersect with the first electrode and closer to a touch surface than the first electrode,
transmitting an uplink signal to the stylus using the second electrode;
performing detection of a downlink signal transmitted from the stylus in response to the uplink signal using both the first and second electrodes, and detecting a position of the stylus based on the detected downlink signal;
after transmitting the uplink signal, detecting the downlink signal using only the second electrodes, thereby detecting the downlink signal using both the first and second electrodes to detect the position of the stylus after the downlink signal is detected ;
controller . A controller that detects the position of a stylus using a first electrode and a second electrode disposed closer to a touch surface than the first electrode and intersecting the first electrode,
transmitting an uplink signal to the stylus using the second electrode;
performing detection of a downlink signal transmitted from the stylus in response to the uplink signal using both the first and second electrodes and determining the position of the stylus based on the detected downlink signal; detect,
The first and second electrodes are each provided in an in-cell liquid crystal display device,
The first electrode is an electrode to which a pixel driving voltage is supplied within the pixel driving period of the liquid crystal display device, while the second electrode is an electrode to which the pixel driving voltage is supplied within the pixel driving period. is an electrode that is not supplied with
controller . The first and second electrodes are arranged between the touch surface and a pixel electrode provided on the liquid crystal display device.
The controller according to claim 2 . The uplink signal includes a signal including a command transmitted every display period of the liquid crystal display device, and a shortened synchronization signal transmitted every pixel drive period.
The controller according to claim 2 .

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