JP2017220187A - Position detection device and position detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detection device placed on an image display device.SOLUTION: A position detection device includes: a resonance circuit; a transmission unit for transmitting an electromagnetic wave; a reception unit for receiving the electromagnetic wave radiated by the resonance circuit; a first ladder-like antenna by providing one-turn loop coils together and forming a ladder-shaped continuous loop coil; a second ladder-like antenna provided by rotating a similar ladder-shaped antenna by 90 degrees; a loop connection switching unit capable of selectively connecting both ends of a loop coil group; a transmission/reception switching unit capable of connecting a connection line from the loop connection switching unit with the transmission unit or the reception unit by switching between them; and a signal processing unit for calculating an instruction position on the basis of characteristic distribution of a received signal. The antennas allow people to visually recognize an opposite side. They are formed on a transparent base material. An opacity conductive material is made into a thin wire and a mesh shape. It is any of copper, aluminum or silver, or alloy including them. The reception unit includes a differential reception circuit and removes a common mode noise.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a position detection device that transmits position information of a position indicator from a cordless position indicator to a tablet. In particular, the present invention relates to an image display device that is provided on the upper side of the image display device, and the sensor is made of a mesh-like metal wire.

Patent Document 1 (published on May 27, 1994) describes an example of an electromagnetic induction oscillation digitizer.
Patent Document 2 (issued on March 6, 2000) describes an electromagnetic induction type position detection device that detects a coordinate by fixing a transmission antenna and switching a reception antenna.
Patent Document 3 (published on December 17, 2001) discloses an electromagnetic induction type position detection device that transmits a signal from a loop coil that surrounds an outer periphery.
Patent Document 4 (issued on April 8, 2002) describes an electromagnetic induction type position detection device that sends a signal after phase inversion.
Patent Document 5 (issued on July 13, 2004) discloses an example in which electromagnetic induction and pressure-sensitive resistance or electrostatic finger touch are realized with a transparent pattern.
Patent Document 6 (issued on September 4, 2007) discloses an example of realizing an electromagnetic induction pen.
Patent Document 7 (published on November 24, 2015) describes an electromagnetic induction type position detection device that is driven by a Y-axis transmission antenna and detected by an X-axis reception antenna.
Patent Document 8 (issued on May 7, 2015) discloses an electromagnetic induction type position detection device using a sensor constituting a parallel resonant circuit.

Japanese Patent Laid-Open No. 06-149451 Japanese Patent No. 3015269 Japanese Patent No. 3239195 Japanese Patent No. 3273669 US Pat. No. 6,676,752 US Pat. No. 7,265,303 Specification Japanese Patent No. 5819565 Japanese Patent No. 5714194

  In order to detect a pen touch, it is advantageous to dispose an electromagnetic induction sensor on the image display device (side viewed from the operator). However, since a transparent conductive film such as ITO has a high electric resistance value, it has been difficult to actually realize an electromagnetic induction pen sensor. Increasing the number of turns (number of turns) of the loop coil increases the electromagnetic wave. However, in the sensor placed on the image display device, it is difficult to form a through hole in the transparent film, so the number of turns is one turn. Is desirable. Further, in order to receive an electromagnetic wave signal returned from the resonance circuit, there is a problem that noise generated from the image display device side should be cleared.

Recently, there has been a technique that does not obscure the image display device even though a conductive wire is provided on the image display device by a thin metal wire called a metal mesh.
The inventor of the present invention uses a one-turn loop coil that does not use a through hole, supplies electric power to an electronic pen incorporating a resonance circuit in a non-contact manner, and receives an electromagnetic wave signal returned from the resonance circuit. The resonance circuit of the electronic pen of the electromagnetic induction type position detection device under various constraints such as clearing the noise from the device and enabling the combined use with the electrostatic induction type touch sensor. I thought that it would be possible to use a metal mesh to supply power from the sensor, and as a result of studying every day, I finally realized it.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a position detection device and a position detection method that are arranged on an image display device (side viewed from an operator).

  The present inventor has found that an electromagnetic induction type position detecting device provided on an image display device can be realized by a sensor using a metal mesh. In addition, a technique for receiving and processing a signal returned from the resonance circuit of the position indicator has been found together.

  That is, a position detection device according to the present invention includes a position indicator having a resonance circuit capable of transmitting and receiving an electromagnetic induction signal, a transmission unit that transmits an electromagnetic wave that can resonate in the resonance circuit of the position indicator, A receiving unit that receives electromagnetic waves radiated from the resonance circuit and a plurality of rectangular one-turn loop coils are arranged so as to be in continuous contact with each other, and by making the contact side common, a ladder-like continuous A ladder-shaped continuous antenna is formed by arranging a first ladder-shaped antenna, which forms a loop coil, and a plurality of rectangular one-turn loop coils so as to be in continuous contact with each other, and by sharing a contact side. A ladder antenna in which a loop coil is formed, wherein the first ladder antenna includes a second ladder antenna rotated by 90 degrees, and each of the ladder antennas. A loop connection switching unit that can select and connect both ends of the loop coil group that constitutes the connection, a transmission / reception switching unit that can be connected by switching the connection line from the loop connection switching unit to the transmission unit or the reception unit, And a signal processing unit that calculates an indication position of the position indicator based on a characteristic distribution of the signal received by the reception unit. Thereby, the position detection apparatus arrange | positioned above an image display apparatus can be provided.

  The first ladder-shaped antenna and the second ladder-shaped antenna are formed of a conductor that allows a person operating the position indicator to visually recognize the other side of the ladder-shaped antenna, and is transparent. It is formed on a base material. Thereby, it can arrange | position to the upper side of an image display apparatus, and can make the display of an image display apparatus visible.

The first ladder-shaped antenna and the second ladder-shaped antenna can make the other side of the ladder-shaped antenna visible by thinning an opaque conductive material into a mesh shape. Accordingly, it is possible to provide a position detection device that does not hinder the display of the image display device despite using an opaque material.

  The opaque conductive material may be any metal of copper, aluminum, or silver or an alloy containing any of these metals. Thereby, an advantageous configuration in terms of electrical resistance can be provided.

  The receiving unit includes a differential receiving circuit that differentially detects signals from both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna, and is superimposed on the loop coil. Remove common mode noise. Thereby, the noise emitted from the image display apparatus can be canceled.

  By connecting a parallel resonance capacitor to the output end of the transmission unit, the loop coil constituting the first ladder antenna or the second ladder antenna and the parallel resonance capacitor resonate to drive. A resonance current is generated and the drive resonance current is output. This increases the drive current.

  The receiving unit has a synchronous detection circuit corresponding to the frequency of the signal, and obtains phase information of the signal. As a result, information such as a change in the state of the position indicator can be transmitted to the position detection device.

  The transmission unit has an inverting drive circuit capable of sending a drive signal to be inverted to both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna. The power supply voltage can be doubled. Thereby, since the loop coil is one turn, the disadvantage that the transmission radio wave is weak can be covered.

  The transmitter has a plurality of frequency sources capable of selecting and transmitting one frequency from electromagnetic waves having a plurality of frequencies according to the type and state of the position indicator. Thereby, for example, a pen-shaped position indicator, an eraser-shaped position indicator, a colored pen-shaped position indicator, etc. are provided with resonance circuits having different resonance frequencies, respectively. By transmitting and identifying the frequency that was actually received, the pen type can be determined.

  The loop connection switching unit can take different antenna configurations when transmitting electromagnetic waves to the position indicator and receiving electromagnetic waves from the position indicator. This increases the degree of freedom in changing the width of the loop coil, phase inversion, and the like.

The loop connection switching unit is fixed to one antenna configuration capable of sending a strong electromagnetic wave to the position indicator during transmission of the electromagnetic wave to the position indicator in a unit sequence for coordinate detection, When receiving an electromagnetic wave from the position indicator, a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection are employed. As a result, a constant and strong radio wave is sent to the resonance circuit of the position indicator as compared with a method in which transmission and reception are performed by the same loop coil while the loop coil is sequentially switched to obtain a signal distribution necessary for coordinate detection. As a result, the returned electromagnetic wave signal can be increased.
The unit sequence refers to a series of processes for measuring the distribution of characteristics such as signal strength and phase by sequentially transmitting and receiving while changing the position of the antenna in order to detect the position indicated by the position indicator. It is necessary to finish the position indicator within a predetermined time which is considered not to have moved greatly.

  The loop connection switching unit takes a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection during transmission of electromagnetic waves to the position indicator in a unit sequence for coordinate detection. When receiving the electromagnetic wave from the position indicator, the antenna is fixed to one antenna configuration capable of receiving a strong electromagnetic wave from the position indicator. Thereby, since the weak electromagnetic wave which returns from the coil of a resonance circuit is received in the position which can be received most strongly, reception strong against noise can be performed.

  The receiving unit includes a first receiving unit connected to the first ladder-shaped antenna, and a second receiving unit connected to the second ladder-shaped antenna, and the first ladder-shaped unit The antenna and the second ladder antenna can be received simultaneously. Thereby, signals in both the X direction and the Y direction can be processed simultaneously.

  The loop connection switching unit changes connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that an effective loop coil By changing the width, the width can be selected according to the height and posture of the position indicator. This makes it possible to perform appropriate processing depending on the situation, such as position detection processing when the coordinates of the position indicator are lost, position detection processing for obtaining detailed coordinates while grasping the rough coordinates of the position indicator. can do.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are simultaneously connected, the resistance of the loop coil is reduced, the supply current is increased, and the electromagnetic wave transmitted to the position indicator is strengthened. Thereby, the electromagnetic wave signal returned from the position indicator can be strengthened, which is advantageous for the reception process and the coordinate detection process.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are connected at the same time, and a plurality of loop coils are simultaneously realized as a closed circuit. This makes it ideal for scanning loop coils of various sizes in random order, or losing sight of the position indicator without sticking to sequentially scanning the loop coils of the smallest unit size. Various processes such as finding a proper scan order and executing it are possible.

  A part of the plurality of loop coils realized as a closed circuit at the same time is connected so as to invert a loop current during transmission or reception. This enables signal control and signal processing including phase inversion processing.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are connected at the same time, and by transmitting simultaneously from each ladder antenna, it has become possible to send a stronger electromagnetic wave to a specific position. As a result, it is possible to transmit an electromagnetic wave aiming at the position of the position indicator.

  The respective ladder antennas of the first ladder antenna and the second ladder antenna are formed on different planes, and each rectangular antenna constituting the respective ladder antennas is formed. Capacitance detection that detects the change in capacitance at the point where each wire antenna group on the two planes intersects with the center line that specifies the position of the loop coil, and is provided with linear wire antennas. A touch screen such as an operator's finger can be detected. Thereby, not only can position detection be performed by an electromagnetic induction method, but it can also be used as a touch panel using electrostatic capacitance.

  The transparent base material is provided on the front surface of a display device that displays an image. Thereby, it becomes easy to stack the position detection device on the image display device.

  The position detection method in the present invention is a position detection method in the position detection device, wherein the transmission unit connects a parallel resonance capacitor to an output terminal of the transmission unit, and the first ladder antenna or the first The loop coil constituting the two ladder antennas and the parallel resonance capacitor are resonated to generate a drive current and output the drive current. This increases the drive current.

  The position detection method in the present invention is a position detection method in the position detection device, and the reception unit performs synchronous detection according to the frequency of the signal to obtain the phase information of the signal. As a result, information such as a change in the state of the position indicator can be transmitted to the position detection device.

  The transmitter sends a driving signal that is inverted to both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna, and apparently doubles the power supply voltage. . The disadvantage of having one loop coil can be covered.

  The transmission unit selects and transmits one frequency from electromagnetic waves having a plurality of frequencies according to the type and state of the position indicator. This makes it possible to distinguish between a pen-shaped position indicator, an eraser-shaped position indicator, and a colored pen.

  The loop connection switching unit has different antenna configurations when electromagnetic waves are transmitted to the position indicator and when electromagnetic waves are received from the position indicator. This increases the degree of freedom in changing the width of the loop coil, phase inversion, and the like.

  The loop connection switching unit is fixed to one antenna configuration capable of transmitting a strong electromagnetic wave to the position indicator during transmission of the electromagnetic wave to the position indicator in a unit sequence for coordinate detection, When receiving an electromagnetic wave from the position indicator, a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection are employed. As a result, a constant and strong radio wave is sent to the resonance circuit of the position indicator as compared with a method in which transmission and reception are performed by the same loop coil while the loop coil is sequentially switched to obtain a signal distribution necessary for coordinate detection. As a result, the returned electromagnetic wave signal can be increased.

  The receiving unit includes a first receiving unit connected to the first ladder-shaped antenna, and a second receiving unit connected to the second ladder-shaped antenna, and the first ladder-shaped unit Reception is simultaneously performed by the antenna and the second ladder antenna. Thereby, signals in both the X direction and the Y direction can be processed simultaneously.

  The loop connection switching unit changes connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that an effective loop coil The width is changed, and the width is selected according to the height and posture of the position indicator. As a result, appropriate processing is performed according to the situation, such as position detection processing when the coordinates of the position indicator are lost, and position detection processing for obtaining detailed coordinates in a state where the rough coordinates of the position indicator are grasped. be able to.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are simultaneously connected, the resistance of the loop coil is reduced, the supply current is increased, and the electromagnetic wave transmitted to the position indicator is strengthened. Thereby, the electromagnetic wave signal returned from the position indicator can be strengthened, which is advantageous for the reception process and the coordinate detection process.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are connected at the same time, and a plurality of loop coils are closed at the same time. This makes it ideal for scanning loop coils of various sizes in random order, or losing sight of the position indicator without sticking to sequentially scanning the loop coils of the smallest unit size. Various processes such as finding a proper scan order and executing it are possible.

  A part of the plurality of loop coils realized as a closed circuit at the same time is connected so as to invert the loop current during transmission or reception. This enables signal control and signal processing including phase inversion processing.

  The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are transmitted at the same time, and a strong electromagnetic wave is transmitted to a specific position by transmitting simultaneously from each ladder antenna. As a result, it is possible to transmit an electromagnetic wave aiming at the position of the position indicator.

  The position detection apparatus of the present invention is an electromagnetic induction type position detection apparatus, and has an advantage that it is not placed on (attached to) an image display apparatus and does not interfere with visual recognition of an image.

In order to show the basic configuration of the position detection device 10 of the present invention, it is a diagram depicting the relationship between the first ladder antenna 1, the transmission unit 3, the reception unit 4, the loop connection switching unit 5, and the position indicator 8. . This is an example of a position detecting device provided with a second ladder antenna 2 in addition to the configuration of FIG. 1 so that XY coordinates can be acquired. It is a figure which shows the example which a 1st receiving part and a 2nd receiving part can operate | move simultaneously. It is a figure which shows the example which strengthens the electromagnetic waves transmitted from a loop coil to a position indicator by increasing the number of loop coils connected simultaneously. It is a figure explaining a broad scan and a narrow scan. It is a figure explaining the operation | movement which inverts a phase with the adjacent loop coil at the time of transmission, and supplies a drive current. It is a figure which shows the circuit structure in the case of inversion drive. It is a figure which shows the circuit structure of the transmission part in the case of parallel resonance. It is a figure which shows the structure which piled up the electrostatic induction type touch panel on the position detection apparatus of the electronic induction type. It is a figure which shows the example of 1 axis | shaft transmission and 2 axis | shaft reception. It is a figure of 1 axis all scans.

Hereinafter, an embodiment for carrying out an apparatus according to the present invention will be described in detail with reference to the drawings. Similar components will be described with the same reference numerals.
<Embodiment 1>
<Configuration>
1 to 3 are diagrams illustrating Embodiment 1 of the present invention. Here, FIG. 1 shows a basic configuration of the position detection device 10 of the present invention, a first ladder antenna 1, a transmission unit 3 (preferably a transmission unit having an inverting drive circuit), and a reception unit 4 (preferably FIG. 6 is a diagram illustrating a relationship among a receiving unit having a differential receiving amplifier), a loop connection switching unit 5, and a position indicator 8. The reason why the differential reception amplifier is used is to remove (cancel) common node noise superimposed on each ladder antenna. Similarly, it is desirable that the transmission unit has an inversion driving circuit.

As shown in FIG. 1, the first ladder-shaped antenna 1 has a shape in which five minimum unit rectangles are connected. That is, the long side of the minimum unit rectangle is common to the long sides of adjacent rectangles. In addition, for one of the two short sides, the short sides are connected and extend. The other short side is electrically opened and is connected to a switch constituting the loop connection switching unit 5.
In FIG. 1, the first ladder-like antenna 1 is drawn for illustration, but the drawing of the second ladder-like antenna 2 is omitted. The transmission unit 3 is connected to the ladder antenna 1 through the loop connection switching unit 5. The receiving unit 4 is connected to the ladder antenna 1 through the loop connection switching unit 5.

The first ladder-shaped antenna 1 (the same applies to a second ladder-shaped antenna 2 described later) is formed of a conductor that makes the other side visible. The conductor that makes the other side visible can include a transparent conductive film such as ITO. If a transparent conductive film having a sufficiently small resistance value is available, it can be used in the present invention. However, at the time of filing this application, a transparent conductive film having a sufficiently small electric resistance value cannot be obtained. Therefore, in the present invention, the ladder-shaped antenna is formed using a metal fine wire formed in a mesh shape (metal mesh). Although this thin metal wire is opaque per se, it is thin enough so that it does not interfere with the visual recognition of the other side. As a specific material, any metal of copper, aluminum, or silver can be used. Moreover, the alloy containing any of those metals may be sufficient.
About the manufacturing method which forms a metal fine wire with a metal mesh, it is as follows. The method of creating a transparent conductor with the lowest resistance is currently a method of removing unnecessary metal by etching and leaving a mesh-like metal wire after laminating a metal sheet on the base film. . In addition to this, a method of forming a metal layer on a film using electrolytic plating or electroless plating, or a method of printing a conductive pattern by a printing technique may be used.
The first ladder antenna 1 (and a second ladder antenna 2 described later) is formed on a transparent base material. The base material is, for example, a flexible transparent member, and is configured so that it can be attached to the surface of the image display device, and is transparent so as not to obstruct the display of the image displayed on the image display device. Have

Here, the loop connection switching unit 5 includes the switches a, b, c,..., L, m, n and the wirings shown in the figure, that is, the wirings that connect each of the loop coil groups and the switches, and the switches a, b, It consists of the wiring which connects c, d and switch e, f, g, ..., l, m, n. For example, the loop connection switching unit 5 can be configured using an analog switch, a multiplexer, or the like.
The position indicator 8 has a resonance circuit 9 (not shown) as its basic configuration. The resonance circuit 9 is an LC circuit, which is a passive circuit including a coil and a capacitor, and receives an electromagnetic wave having a frequency close to a resonance frequency (tuning frequency) determined by the inductance of the coil and the capacitance of the capacitor. This causes a resonance phenomenon.

<Operation 1>
In FIG. 1, the switch a, e, n, and b are closed by a function of a control device (not shown) and a drive current is supplied from the transmission unit 4. Then, the loop coil of the largest rectangle (a rectangle having a five times the area of the smallest unit rectangle) composed of the loop coils of the first ladder antenna is realized as a closed circuit. And the drive current from the transmission part 4 flows through the closed loop coil. As a result, electromagnetic waves are transmitted from the closed loop coil toward the position indicator 8. The frequency of the electromagnetic wave is close to the resonance frequency of the resonance circuit 9, and the resonance circuit 9 provided in the position indicator 8 resonates.
Next, while the resonance continues, the switches a and b are opened and the switches c and d are closed. At this time, the switches e and n remain closed. That is, a large rectangular loop coil is connected to the receiving unit 4 with the four switches c, e, n, and d closed. At this time, the loop coil receives the electromagnetic wave returned from the resonance circuit 9 and gives the signal to the receiving unit 4.
By obtaining this received signal, it can be known that the position indicator 8 exists within the area of this sensor. When the position detection device 10 has both an electromagnetic induction type sensor and a capacitance type touch sensor, by confirming the presence of the position indicator 8, the touch sensor (capacitance type) It is possible to disable the operation and enable the electromagnetic induction type position detection processing (palm rejection). Therefore, even when the touch sensor is operating, it is desirable to perform this operation 1 periodically.

<Operation 2>
The operation 2 is one of basic operations for detecting the coordinates of the position indicator 8. This is a method of obtaining a signal distribution required for coordinate detection by sequentially switching the loop coil while performing transmission and reception with the same loop coil to the resonance circuit 9 of the position indicator 8.
That is, in FIG. 1, with the switches e and f closed, the switches a and b are closed and transmitted, the resonance circuit 9 of the position indicator 8 is resonated, and the switches a and b are immediately opened. The switches c and d are closed and the electromagnetic wave signal returned from the resonance circuit 9 is received. Next, the switches e and f are opened, the switches g and h are closed, and the same operation is executed. Furthermore, i, j. k, l. m, n. The received signal is obtained from the five loop coils (minimum unit loop coil). Coordinates (here, Y coordinates) are calculated from the distribution state of these received signals.
The coordinates of the position indicator 8 are only the Y coordinates in the configuration of FIG. 1, but by providing not only the first ladder antenna 1 but also the second ladder antenna 2 as shown in FIG. Both XY coordinates can be acquired. The acquired XY coordinates are input to the computer, and are processed as input information to the computer in the same manner as information from an input device such as a keyboard or a mouse.
FIG. 2 shows an example of a position detection device provided with a second ladder antenna 2 in addition to the configuration of FIG. 1 so that XY coordinates can be acquired. For example, the scan operation for detecting the X coordinate is executed immediately after the scan operation for detecting the Y coordinate (the operation of acquiring a reception signal of each loop coil by switching a series of switches by the loop connection switching unit 5). By doing so, the XY coordinates indicated by the position indicator 8 can be detected.

<Operation 3>
The receiving unit 4 is provided with a synchronous detection circuit corresponding to the frequency of the signal so that the phase information of the received signal can be acquired, and the resonance frequency of the resonance circuit 9 is slightly set on the position indicator 8 side. If the switch (or writing pressure detection sensor) for shifting the position indicator is provided, the switch information and the writing pressure information of the position indicator 8 can be detected as phase information by the synchronous detection circuit. It is possible to perform an operation of acquiring on / off information and writing pressure information.
The phase information can be detected using the received signal for coordinate detection as it is, but in an operation different from the coordinate detection (an operation for selecting a larger range of loop coils by the loop connection switching unit 5). It is also possible to use the obtained received signal.

<Operation 4>
As shown in FIG. 3, the operation 4 is configured so that the receiving unit 4 includes a first receiving unit 41 and a second receiving unit 42, which operate simultaneously, and can receive and process signals. Thus, the X coordinate and the Y coordinate can be processed simultaneously.
In the above-described operation 2, the transmission and reception are performed by the same loop coil, and the loop coil is sequentially switched to obtain a signal distribution necessary for coordinate detection. In order to realize the operation 4, it is premised that different antenna configurations are employed when the electromagnetic wave is transmitted to the position indicator 8 and when the electromagnetic wave is received from the position indicator 8. In particular, a unit sequence for coordinate detection (a series of measuring the distribution of characteristics such as signal strength and phase by sequentially transmitting and receiving while changing the position of the antenna in order to detect the position indicated by the position indicator. In this case, it is necessary to finish the position indicator within a predetermined time period in which it is considered that the position indicator has not moved greatly.) In transmission, one antenna that can send a strong electromagnetic wave to the position indicator 8 Configuration (for example, in FIG. 3, a small loop surrounding the position indicator by the first ladder antenna and the second ladder antenna by closing the switches a, b, m, n, AB, J, M) In order to select a loop coil on the receiving side, a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection is adopted.
At this time, since the respective received signals can be detected by simultaneously scanning in the X direction and the Y direction, coordinate detection can be performed in half the time compared to the operation 2.
Further, by fixing the transmission antenna to one antenna closest to the position indicator, the power supplied to the resonance circuit 9 of the position indicator (pen) is large and constant, so the state of the resonance circuit is stabilized. . Thereby, there is an advantage that the signal that is returned becomes stronger and scanning on the receiving side can be performed quickly.

<Operation 5>
Similar to the operation 4, the operation 5 is another example in which different antenna configurations are used for transmission and reception. In the unit sequence for coordinate detection, at the time of transmission, it takes a series of different antenna configurations necessary to obtain the signal distribution necessary for coordinate detection, and at the time of reception of electromagnetic waves returning from the resonance circuit of the position indicator This is an operation that adopts an antenna configuration in which it is fixed to one antenna that can receive strong electromagnetic waves from the position indicator.
In this operation, since the state of the resonance circuit varies (in some cases, the signal is inverted), it is necessary to wait for a stable state, and scanning may be slightly delayed. However, since it is possible to receive a weak radio wave returned from the resonance coil at a position where it can be received most strongly, it is possible to receive a signal that is resistant to noise.

<Operation 6>
As shown in FIG. 4, the operation 6 is an example in which the electromagnetic wave transmitted from the loop coil to the position indicator is strengthened by increasing the number of loop coils connected simultaneously. As shown in FIG. 4A, when only the loop coil composed of the minimum unit rectangle is driven, the electromagnetic wave generated due to the problem of the electrical resistance value of the metal mesh that is the material of the loop coil is small. However, as shown in FIG. 4 (b), when driving by simultaneously connecting to a plurality of loop coils, the generated electromagnetic wave increases.
Since the loop connection switching unit 5 in the present invention can freely control the connection by the control of a control unit (not shown), the operation 6 can also be controlled.

<Operation 7>
As shown in FIG. 5, the operation 7 is an operation for switching the connection between the broad scan (FIGS. 5A and 5C) and the narrow scan (FIGS. 5B and 5C). Indicates. When the purpose is to detect rough coordinates when scanning for coordinate detection, a wide loop coil is selected to perform switching operation. This reduces the number of scans and enables high-speed detection.
When performing narrow scan (detailed coordinate detection), the switching operation is performed by selecting the smallest unit loop coil. Broad scan and narrow scan can be changed dynamically. For example, when the rough coordinates of the position indicator are found during the broad scan, the position indicator is narrowed to the range and dynamically shifted to the narrow scan. When the position indicator is lost during the narrow scan, the process immediately shifts to the broad scan. Is possible.

<Operation 8>
The operation 8 is an operation in which the antenna pitch at the time of transmission is different from the antenna pitch at the time of reception. Here, the antenna pitch is not the width of the loop coil but the distance between the centers of the loop coils that are sequentially formed during the scanning operation. In the present invention, the pitch of the loop antennas sequentially formed by switching the loop connection switching unit can also be changed.
As described above, in the unit sequence in which the transmission antenna is fixed and the reception antenna is scanned, the reception antennas sequentially formed are formed at a pitch suitable for coordinate detection. If this pitch is too narrow, a difference in distribution of signal characteristics necessary for coordinate calculation cannot be obtained sufficiently. On the other hand, if the indicated position has moved during the next unit sequence, the position of the transmitting antenna in the next sequence will be moved. A strong signal can be sent at a more appropriate position with respect to the device. Therefore, for example, by narrowing the pitch for forming the transmitting antenna and widening the pitch for forming the receiving antenna, it is possible to obtain both a strong signal level and an appropriate signal distribution. .

<Operation 9>
The operation 9 changes the connection at both ends of the loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna so as to connect both ends of the plurality of loop coils at the same time. This operation is realized as a circuit in which a plurality of loop coils are closed at the same time.
As shown in FIG. 6C, the connection is fixed to the three adjacent loop coils at the time of transmission, and a drive current whose phase is inverted (phase is shifted by 180 degrees) is supplied between the adjacent ones. At this time, at the time of reception, the loop coil is sequentially scanned to receive and process the electromagnetic wave signal returned from the resonance circuit 9 of the position indicator 8.
At this time, when the processing in the receiving circuit is diode detection, that is, absolute value detection, as shown in FIG. 6A, low peaks called so-called side lobes are detected on both sides of the maximum peak of the received signal. . Therefore, since the magnitude of the received signal is recognized as a difference between the high peak and the low peak, there is a disadvantage that the apparent received signal becomes small. Further, when the position indicator is at the end, it may cause the side lobe to be mistakenly recognized as the main lobe (central mountain).
Therefore, as shown in FIG. 6 (b), the processing of the received signal in the receiving circuit is a process called synchronous detection, that is, phase detection. Then, since the received signal is detected as a signal spreading on both sides of the + side and the − side, the signal difference between the high mountain and the low mountain increases. This is advantageous for coordinate detection.

<Operation 10>
As described above, the transmission unit 3 is desirably provided with a differential transmission circuit. An example is shown in FIG. By performing inversion driving with the circuit configuration of FIG. 7, the output amplitude becomes twice the driving voltage.

<Embodiment 2>
<Transmission circuit using resonance phenomenon by LC parallel resonance circuit>
An example in which a parallel resonant circuit is used to further increase the drive voltage from the transmitter 3 will be described.
The transmission unit 3 connects the input side parallel resonance capacitor connected in common to the other end of the loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna, so that the drive current flowing in the loop coil Is caused to resonate by the loop coil and the input side parallel resonance capacitor to generate a drive resonance current.
FIG. 8 shows a circuit configuration of the transmission unit in the case of parallel resonance. As shown in FIG. 8, a resonance capacitor 31, a current limiting resistor 32, an auxiliary inductor 33, a loop resistor 34, and switches S 1, S 2, S 3, and S 4 are provided to supply a driving current to the transmission loop coil 35.
In order to utilize resonance, the drive circuit does not remain connected but needs to be disconnected. Otherwise, the reverse voltage is applied to the drive circuit and is damaged.
The operation will be described on the assumption that both sides drive.
1) When the switches S1 and S4 are turned on, a voltage is applied to both ends of the resonance capacitor 31 to be charged. In FIG. 8 (b), it rises from zero to a position directly above. The current limiting resistor 32 is a small resistor for current limiting that prevents damage to S1 and S4.
2) Thereafter, the switches S1 and S4 are turned off, and a current is passed through the transmission loop coil 35. A current flows at the period of the resonance frequency and comes to a point where the voltage is zero (located at the right end in FIG. 8B). Even if it is as it is, a reverse current continues to flow through the transmission loop coil 35.
3) At that time, the switches S3 and S2 are turned on to apply a reverse voltage.
4) Thereafter, the switches S3 and S2 are turned off. A reverse voltage is applied to the resonant capacitor 31 (the lower position in FIG. 8B). At this time, if the resistance component Zres is ideally zero, the voltage is doubled. Actually, since there is a loss due to the resistance, the voltage increases to some extent or becomes the same voltage as the drive voltage.
5) A current flows from there, and the voltage returns to zero again (the left position in FIG. 8B). The current continues to flow through the transmission loop coil 35 as it is,
6) At that time, the switches S1 and S4 are turned on to apply a voltage. At this time, if the resistance component Zres is ideally zero, the voltage is tripled. However, in actuality, it will be somewhat higher or the same voltage as the drive voltage.
The auxiliary inductor 33 provided after the resonance capacitor 31 is an inductor added for adjusting the resonance frequency because the transmission loop coil 35 of the antenna portion often has an inductance that is too small.
The part of the transmission loop coil 35 is actually configured to switch and connect a plurality of loop coils, but the switching part is omitted.

<Embodiment 3>
<Use with electrostatic capacity method>
The electromagnetic induction type position detection device described above is provided with an antenna on a transparent base material, and is used by being laminated on the upper side of the image display device. Therefore, an electromagnetic induction type position detection device and an electrostatic capacitance type position detection device can be realized in the same plane by providing a capacitive touch pad sensor on the surface using the antenna. According to this configuration, when the electronic pen is not used, the operator touches with a finger to input coordinates, and when the electronic pen is used, the electronic pen is brought close to the input surface to some extent, so that the operation 1 described above is performed. By performing the operation of the described palm rejection, it is possible to shift from the electrostatic capacity type coordinate detection to the electromagnetic induction type coordinate detection.
As shown in FIG. 9, the specific configuration is such that each of the ladder antennas of the first ladder-shaped antenna 1 and the second ladder-shaped antenna 2 is formed in a separate planar shape. A straight wire antenna is provided on each center line that specifies the position of each rectangular loop coil that constitutes the ladder antenna, and a static point at the point where each wire antenna group on the two planes intersects. A capacitance detection unit that detects a change in capacitance is provided. A switch that switches the wire antenna, a transmission unit 53 that transmits a drive signal, and a reception unit 54 that processes a reception signal can be the same as those of the electromagnetic induction type.

<One-axis transmission and two-axis reception (sector scan) for electromagnetic induction coordinate detection>
As described above, since the loop connection switching unit 5 can switch the connection of the loop coil, in order to detect the indication position of the position indicator 8, the control unit ( (Not shown) is controlled to switch the loop coil.
FIG. 10 is an explanatory diagram of sector scan (detailed coordinate detection when the position of a rough position indicator is known). In FIG. 9, the first ladder-like antenna extending horizontally is an antenna for detecting the Y coordinate (Y-axis antenna), and the second ladder-like antenna extending vertically is used for detecting the X coordinate. An antenna (X-axis antenna).
Here, the loop connection switching for the transmitting antenna is performed on the receiving side in a state where a predetermined loop coil of the Y-axis antenna, which can cover the range in which the sector scan is performed, is fixed. In this scan, an X-axis scan and a Y-axis scan are performed. At this time, as described in the operation 4 (FIG. 3), the receiving unit is provided independently of the first receiving unit 41 and the second receiving unit 42 in the X axis and the Y axis, so that the processing of the received signal is performed at the same time in XY. It can be carried out.

<One-axis all-scan for electromagnetic induction type coordinate detection>
FIG. 11 is an explanatory diagram of all-scanning (scanning the entire tablet when the position indicator is unknown). In the all scan, scanning is performed with only one axis (for example, the Y axis) for transmission and reception. When the position indicator is found, the above sector scan is switched.

  The device of the present invention can be widely used in touch panels, tablets, and position detection devices.

DESCRIPTION OF SYMBOLS 1 1st ladder-shaped antenna 2 2nd ladder-shaped antenna 3 Transmission part 4 Reception part 5 Loop connection switching part 6 Transmission / reception switching part 7 Signal processing part 8 Position indicator 9 Resonance circuit 10 Position detection apparatus 31 Resonance capacitor 32 Current limitation Resistor 33 Auxiliary inductor 34 Loop resistor 35 Transmit loop coil 41 First receiver 42 Second receiver 53 Transmitter for touch panel 54 Receiver for touch panel

Claims (32)

A position indicator having a resonance circuit capable of transmitting and receiving electromagnetic induction signals;
A transmitter for transmitting an electromagnetic wave capable of resonating in a resonance circuit of the position indicator;
A receiver for receiving electromagnetic waves radiated from a resonance circuit of the position indicator;
A first ladder-shaped antenna that forms a ladder-like continuous loop coil by arranging a plurality of rectangular one-turn loop coils so as to be in continuous contact with each other, and by sharing a contact side;
A ladder-shaped antenna in which a plurality of rectangular one-turn loop coils are arranged so as to be in continuous contact with each other, and a side to be contacted is used to form a ladder-shaped continuous loop coil, The first ladder-shaped antenna is a second ladder-shaped antenna provided by being rotated 90 degrees;
A loop connection switching unit capable of selecting and connecting both ends of a loop coil group constituting each of the ladder-shaped antennas;
A connection line from the loop connection switching unit, a transmission / reception switching unit connectable by switching to the transmission unit or the reception unit,
And a signal processing unit that calculates an indication position of the position indicator based on a characteristic distribution of the signal received by the reception unit.   The first ladder-shaped antenna and the second ladder-shaped antenna are formed of a conductor that allows a person operating the position indicator to visually recognize the other side of the ladder-shaped antenna, and is transparent. The position detection device according to claim 1, wherein the position detection device is formed on a base material.   The first ladder-like antenna and the second ladder-like antenna are characterized in that the other side of the ladder-like antenna can be visually recognized by thinning an opaque conductive material into a mesh shape. The position detecting device according to claim 2.   4. The position detecting device according to claim 3, wherein the opaque conductive material is one of copper, aluminum, and silver, or an alloy containing any of these metals.   The receiving unit includes a differential receiving circuit that differentially detects signals from both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna, and is superimposed on the loop coil. 5. The position detection device according to claim 1, wherein common mode noise is removed.   By connecting a parallel resonance capacitor to the output end of the transmission unit, the loop coil constituting the first ladder antenna or the second ladder antenna and the parallel resonance capacitor resonate to drive resonance. The position detection device according to claim 1, wherein a current is generated and the driving resonance current is output.   The position detecting device according to any one of claims 1 to 6, wherein the receiving unit includes a synchronous detection circuit according to a frequency of the signal and obtains phase information of the signal.   The transmission unit has an inverting drive circuit capable of sending a drive signal to be inverted to both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna. The position detection device according to any one of claims 1 to 7, wherein the position detection device can be set to be twice the power supply voltage.   The transmission unit includes a plurality of frequency sources capable of selecting and transmitting one frequency among electromagnetic waves having a plurality of frequencies according to the type and state of the position indicator. The position detection device according to any one of claims 1 to 8.   The loop connection switching unit can take different antenna configurations when electromagnetic waves are transmitted to the position indicator and when electromagnetic waves are received from the position indicator. The position detection device according to any one of claims 1 to 9. The loop connection switching unit is a unit sequence for coordinate detection.
When transmitting electromagnetic waves to the position indicator, it is fixed to one antenna configuration that can send strong electromagnetic waves to the position indicator,
11. The position detecting device according to claim 10, wherein when receiving electromagnetic waves from the position indicator, a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection are adopted. The loop connection switching unit is a unit sequence for coordinate detection.
When transmitting electromagnetic waves to the position indicator, a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection are taken,
11. The position detecting device according to claim 10, wherein when receiving the electromagnetic wave from the position indicator, the position detecting device is fixed to one antenna configuration capable of receiving a strong electromagnetic wave from the position indicator. The receiver is
A first receiver connected to the first ladder antenna;
A second receiver connected to the second ladder antenna;
The position detection device according to claim 11 or 12, wherein the first ladder-shaped antenna and the second ladder-shaped antenna can receive simultaneously.   The loop connection switching unit changes connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that an effective loop coil The position detection device according to any one of claims 1 to 13, wherein the width can be selected according to the height and posture of the position indicator by changing the width.   The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends The electromagnetic wave transmitted to the position indicator is strengthened by reducing the resistance of the loop coil to increase the supply current and strengthening the electromagnetic wave transmitted to the position indicator. The described position detection device.   The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends The position detecting device according to any one of claims 1 to 15, wherein a plurality of loop coils are simultaneously realized as a closed circuit.   The position detection device according to claim 16, wherein a part of the plurality of loop coils realized as a closed circuit is connected so as to invert a loop current during transmission or reception.   The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends The electromagnetic waves are transmitted simultaneously from the respective ladder antennas, so that a stronger electromagnetic wave can be sent to a specific position. The position detection apparatus described in item 1. Each of the ladder antennas of the first ladder antenna and the second ladder antenna is formed on a separate plane,
Overlaying the center line that identifies the position of each rectangular loop coil that constitutes each of the ladder antennas, a linear wire antenna is provided.
A capacitance detection unit that detects a change in capacitance at a point where each of the wire antenna groups on the two planes intersects;
The position detection device according to any one of claims 1 to 18, wherein a touch of an operator's finger or the like can be detected.   The position detection device according to any one of claims 1 to 19, wherein the transparent base material is provided on a front surface of a display device that displays an image. A position detection method in the position detection device according to any one of claims 1 to 5,
The transmitter is
A parallel resonance capacitor is connected to the output end of the transmitter,
Resonating the parallel resonance capacitor with a loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna;
Generate drive current,
A position detection method characterized by outputting the drive current. A position detection method in the position detection device according to any one of claims 1 to 5,
The position detecting method, wherein the receiving unit performs synchronous detection according to a frequency of a signal to obtain phase information of the signal. A position detection method in the position detection device according to any one of claims 1 to 5,
The transmitter transmits a drive signal that is inverted to both ends of each loop coil constituting the first ladder-shaped antenna or the second ladder-shaped antenna,
A position detection method characterized in that the drive voltage is apparently twice the power supply voltage. A position detection method in the position detection device according to any one of claims 1 to 5,
The transmission unit selects and transmits one frequency from electromagnetic waves having a plurality of frequencies according to the type and state of the position indicator. A position detection method in the position detection device according to any one of claims 1 to 5,
The position detection method, wherein the loop connection switching unit has different antenna configurations when electromagnetic waves are transmitted to the position indicator and when electromagnetic waves are received from the position indicator. A position detection method in the position detection device according to any one of claims 1 to 5,
The loop connection switching unit is fixed to one antenna configuration capable of transmitting a strong electromagnetic wave to the position indicator during transmission of the electromagnetic wave to the position indicator in a unit sequence for coordinate detection,
A position detection method characterized by adopting a series of different antenna configurations necessary for obtaining a signal distribution necessary for coordinate detection upon reception of electromagnetic waves from the position indicator. A position detection method in the position detection device according to any one of claims 1 to 5,
The receiver is
A first receiver connected to the first ladder antenna;
A second receiver connected to the second ladder antenna;
A position detection method comprising receiving simultaneously by the first ladder-shaped antenna and the second ladder-shaped antenna. A position detection method in the position detection device according to any one of claims 1 to 5,
The loop connection switching unit changes connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that an effective loop coil A position detection method, wherein the width is changed and the width is selected according to the height or posture of the position indicator. A position detection method in the position detection device according to any one of claims 1 to 5,
The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends Are simultaneously connected, the resistance of the loop coil is reduced, the supply current is increased, and the electromagnetic wave transmitted to the position indicator is strengthened. A position detection method in the position detection device according to any one of claims 1 to 5,
The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends A position detecting method characterized in that a plurality of loop coils are simultaneously connected and realized as a circuit in which a plurality of loop coils are closed at the same time.   29. The position detection method according to claim 28, wherein a part of the plurality of loop coils realized as a closed circuit is connected so as to invert a loop current at the time of transmission or reception. A position detection method in the position detection device according to any one of claims 1 to 5,
The loop connection switching unit is configured to change a connection of both ends of a loop coil group constituting each ladder antenna of the first ladder-shaped antenna and the second ladder-shaped antenna, so that a plurality of loop coil ends The position detection method is characterized by transmitting a strong electromagnetic wave to a specific position by transmitting simultaneously from each ladder antenna.

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