JP2018198051A - Position detection system, position detection method, and position detector - Google Patents

Abstract

To be able to posteriorly add a touch panel function to a picture display unit.SOLUTION: A position detection system 1 includes a display 21 provided with a display screen 21a, and a position detector 3 that is detachably mounted and fixed to a rear face of the display 21, and detects the position of an indication body touched to the display screen 21a of the display 21. The position detector 3 has a conductive layer 41 that is arranged to face the display screen 21a of the display 21 and detects the position of the indication body touched to the display screen 21a, and a detection side operation part that calculates the position of the indication body approached to the conductive layer 41 on the basis of the output signal from the conductive layer 41. A positional information of the indication body calculated at the detection side operation part is transmitted to a communication part 23 of the display 21 via a communication part 32 of the position detector 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position detection device, a position detection system including the position detection device and an image display device, and a position detection method.

  Some computer devices such as personal computers, smartphones, and tablets employ a display in which a capacitive touch panel is provided on the front surface of a display screen. Such a display can operate a computer device or input characters by bringing an indicator such as a finger into contact with a display on which an image is displayed without operating an operation unit such as a mouse. (For example, Patent Document 1).

  Patent Document 2 discloses a patternless touch panel in which electrodes are provided on four sides of a transparent conductive film and an AC voltage for position detection having the same phase and the same potential is supplied. Specifically, four waveform detection circuits are provided corresponding to the electrodes at the four corners of the conductive film, and the coordinate position is calculated based on the output voltage of the detection circuit.

JP 2012-138067 A International publication WO2013 / 153609 pamphlet

  In recent computer equipment, an operating system and various software are designed to be adapted for touch operation.

  However, many stationary computer devices called desktop personal computers and laptop computer devices called notebook personal computers do not have a touch panel function. For example, an old notebook computer has a problem that although it can still be used sufficiently, it does not have a touch panel, so some functions of the software cannot be used. In general, since it is difficult to design a touch panel by replacing the display portion of a notebook computer, there has been a problem that a set of notebook computers must be purchased separately in order to perform touch panel operations. Further, even if the touch panel function is provided, if the touch panel fails, even if there is no problem with the image display on the display, it may not be possible to perform an operation by touch.

  Therefore, the present invention provides a position detection system that can add a touch panel function to the image display device afterwards even if the image display device has a touch panel that does not have a touch panel function or does not function normally. With the goal.

  In order to achieve the above object, in the position detection system according to the present invention, a position detection device that is detachably attached and fixed to the back side of the image display device is provided, and position information detected by the position detection device is displayed on the image display device. Was sent to.

  That is, a position detection system according to an aspect of the present invention includes an image display device provided with a display screen, and a position of an indicator touching the display screen that is detachably attached and fixed to the back surface of the image display device. A position detecting device for detection. The image display device includes a display-side communication unit configured to be able to communicate with the position detection device. In addition, the position detection device is disposed opposite to the display screen and is disposed apart from the conductive layer for detecting the position of the indicator touching the display screen, each of which is the conductive layer A plurality of electrodes connected to each other, a signal source that provides a measurement signal to a pair of electrodes selected from the plurality of electrodes, and difference information between output signals output from the pair of electrodes to which the measurement signals are applied Based on the detection side calculation unit that calculates the position of the indicator approaching the conductive layer, and transmits the position information of the indicator calculated by the detection side calculation unit to the display side communication unit of the image display device And a detection side communication unit.

  Here, the “image” is a concept including a still image and a moving image.

  Further, “touching” is a concept including both a direct touch on the display screen (contact with the display screen) and an indirect touch on the display screen (so-called hovering).

  The position detection system according to the above aspect is configured to detect the position of the indicator that has touched the display screen of the image display device by the position detection device attached and fixed to the back surface of the image display device. Furthermore, the touch position of the indicator on the display screen detected by the position detection device is transmitted from the detection side communication unit to the display side communication unit. Thereby, the image display device can execute processing related to the touch operation of the user (indicator) by comparing the touch position received from the position detection device with the image displayed on the display screen. That is, even for an image display device that does not have a touch panel function or a touch panel that does not function properly (image display device), the touch panel function can be added to the image display device afterwards.

  As described above, according to the present invention, since the touch position of the indicator can be detected by the position detection device attached and fixed to the back surface of the image display device, a touch panel function is added to the image display device afterwards. Can do.

It is a schematic block diagram of a position detection system. It is a front view which shows schematic structure of a position detection apparatus. It is a schematic sectional drawing in the III-III line of FIG. It is a schematic sectional drawing in the IV-IV line of FIG. It is a schematic diagram which shows an example of the relationship between the position and magnitude | size of the display screen of a display, and the detection area of a position detection part. It is a schematic diagram which shows the other example of the relationship between the position of the display screen of a display, and the detection area of a position detection part, and a magnitude | size. It is a block diagram which shows the function structure of a position detection system. It is a flowchart which shows an example of the detection operation of the touch position of a position detection system. It is a flowchart which shows the detection operation of the touch position of a position detection apparatus. It is the figure which showed an example of the signal waveform when the point TP of FIG. 2 is touched. It is a flowchart which shows the other example of the detection operation of the touch position of a position detection system. It is a flowchart which shows the setting operation | movement of a reference coordinate. It is a figure for demonstrating the detection operation of a touch position.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

  As shown in FIG. 1, a position detection system 1 according to the present embodiment includes a computer device 2 having a display 21 and a position detection device 3 configured to be attached / detached to / from the back surface of the display 21. I have. In the display 21, a surface on which the display screen 21a is displayed is a front surface, and a surface facing the front surface is a back surface. The front side may be referred to as the front side, and the back side may be referred to as the back side. The direction from the back side to the front side may be referred to as the front, and the direction from the front side to the back side may be referred to as the rear.

  The position detection system 1 is configured to detect the touch position TP when an indicator (for example, an operator's finger or the like) approaches or contacts the display screen 21a of the display 21. In the present embodiment, the touch means both an operation state in which the indicator directly touches the display 21 and an operation state in which the indicator approaching the display 21 moves in a non-contact state (so-called hovering operation state). It is a concept that includes Further, the touch of the indicator on the display 21 is simply referred to as “touch”. The touched position when the indicator touches the display 21 and the position on the conductive layer 41 corresponding to the position of the indicator are referred to as “touch position TP”.

  Hereinafter, each component of the position detection system will be described in detail.

≪Computer equipment (electronic equipment) ≫
FIG. 1A illustrates a general-purpose laptop computer device 2 including a horizontally long display 21 that does not have a touch panel function as an electronic device. The computer device 2 includes a computer main body 20 and a display 21.

  The computer body 20 includes an input operation unit 22 such as a keyboard and a mouse, a communication unit 23 (see FIG. 7) configured to be capable of communication such as USB communication, a CPU 24 (see FIG. 7), and a storage such as a hard disk drive. Unit 25 (see FIG. 7).

  The communication unit 23 is configured to be able to perform bidirectional communication with a communication unit 32 (see FIG. 7) of the position detection device 3 to be described later. A communication method related to bidirectional communication is not particularly limited, and may be wireless communication, wired communication, or both. FIG. 1 shows an example in which the computer device 2 and the position detection device 3 are connected by wire, and the computer device 2 is provided with an interface port 23a.

  In the present embodiment, the computer apparatus 2 is described as an example of the electronic apparatus. However, the technique according to the present disclosure can be applied as long as an image display apparatus that displays an image on at least a display screen is included. . For example, electronic devices including an image display device widely include televisions, smartphones, tablets, electronic book readers, electronic music players, mobile phones, and the like. In the example of FIG. 1A, an integrated computer device in which the computer main body 20 and the display 21 are integrated is shown. However, the computer main body 20 and the display 21 are physically separated. Also good.

<Display (image display device)>
The display 21 as an image display device can display an image on a display screen 21a formed on the surface, and specifically, image information such as software executed by a computer device is displayed. The image includes a still image and a moving image. Note that the display form, display principle, display method, and the like of the display 21 are not particularly limited. Examples of the display 21 include a liquid crystal display, an organic EL display, a plasma display, a surface conduction electron-emitting device display, a particle movement type electronic paper, and the like. The display 21 may include a backlight, a light reflecting plate, a light reflecting sheet, and the like.

  The thickness (front and back direction) of the display 21 is not particularly limited, but is preferably 5 cm or less from the viewpoint of securing stable detection accuracy of the touch position TP. Moreover, it is preferable that the back surface of the display 21 is flat, and if it is flat, the position detection device 3 can be easily attached, and the position stability after the attachment is high.

≪Position detection device≫
The position detection device 3 is a patternless detection device (hereinafter referred to as a patternless detection device), and is disposed on the back side of an image display device that displays a display screen that functions as a touch panel. FIG. 1 (c) shows an example in which the position detection device 3 is attached and fixed to the back side of the display 21 of the laptop computer device 2, and the presence / absence of touch on the display 21 and the touch position TP are detected. It is configured to be able to. Specifically, the position detection device 3 includes a position detection unit 4 (see FIG. 2) provided with a detection region Rd for detecting the position of the indicator touching the display screen 21a of the display 21, and a position detection unit. 4 is provided with an attachment mechanism 31 for attaching and fixing 4 to the back side of the display 21 and a communication unit 32 for performing bidirectional communication with computer equipment.

  Below, each structure of a position detection apparatus is explained in full detail.

<Mounting mechanism>
The attachment mechanism 31 only needs to be configured so that the position detection device 3 can be detachably attached to the back surface of the display 21, and the specific attachment structure and attachment method are not particularly limited. For example, the attachment mechanism 31 may be realized by hooks that can be hooked to the peripheral end of the display 21 as shown in FIG. 1B (in FIG. 1B, both lateral sides of the upper end). Moreover, the attachment mechanism 31 may have a screwing mechanism, and may be comprised so that it can affix with a double-sided tape, an adhesive sheet, or a suction cup. Furthermore, the attachment mechanism 31 may be a rubber band that is used by being hung around the outer periphery of the display 21. If the back surface of the display 21 is made of a magnetic material, it may be a magnet or the like that is adhered to the back surface. Good. In mounting and fixing, it is more preferable that attachment / detachment is high and that fixing strength, positional stability and adhesion stability at the time of mounting and fixing are high, and the above elements may be combined for realizing them. For example, by combining the collar portion with a suction cup, an adhesive sheet, and the like, the fixing strength, the positional stability, and the adhesion stability during mounting and fixing can be increased.

<Communication unit (detection side communication unit)>
The communication unit 32 is configured to perform bidirectional communication with the communication unit 23 of the computer device 2. A communication method related to bidirectional communication is not particularly limited, and may be wireless communication, wired communication, or both. In the present embodiment, an example is shown in which the communication unit 32 includes an interface circuit (not shown) provided in a position detection circuit 5 (see FIG. 7) described later and a communication cable 32a. One end of the communication cable 32 a is connected to the terminal of the position detection circuit 5, and the other end is provided with a connector 32 b for connecting to the interface port 23 a of the computer device 2. Although not shown, an interface port may be provided on the position detection device 3 side, and one end of the communication cable 32a may be connected to the interface port. When the position detection device 3 and the computer device 2 are connected by wireless communication, the communication unit 32 includes an antenna (not shown) provided integrally with the position detection circuit 5 or separately.

<Position detector>
As shown in FIGS. 2 to 4, the position detection unit 4 includes a base body 40 having a conductive layer 41 and a wiring 42 formed on the surface thereof, and a position detection circuit 5 mounted on the base body 40. The outer shape and size of the position detection unit 4 (base 40) are not particularly limited. For example, the position detection unit 4 is configured so that the outer dimensions are substantially the same as those of the display 21. Thereby, the position alignment at the time of attaching and fixing the position detection part 4 to the display 21 becomes easy.

  The position detector 4 may be entirely or partially covered with a protective member (not shown). For example, the entire outer surface of the position detection unit 4 may be covered with a protective member formed of resin or the like, or specific portions such as a conductive layer, an electrode, and a wiring may be protected by the protective member. That is, it is possible to apply a protective member whose design has been changed as appropriate in order to improve the design of the display 21 or to improve various performances such as durability and weather resistance. Note that the position detection device 3 can detect the touch position even when the entire position detection unit 4 is covered with the protective member.

-Substrate-
Although the shape of the base | substrate 40 is not specifically limited, For example, it is a rectangular sheet form (film shape or thin plate shape) and a rectangular flat plate shape. For example, if the base body 40 is in the form of a sheet, when the back surface of the display 21 is uneven or curved, there is a merit that the position detection unit 4 can be formed by deforming the base body 40 along the shape. . For example, if the base 40 is flat, there is an advantage that when the back surface of the display 21 is flat, it is easy to mount and fix to the back side of the display 21 and the mounting stability is high. Note that the base body 40 does not have to be formed of a single object. For example, a conductive sheet having a conductive layer formed on the front or back surface of an insulating sheet is provided, and the conductive sheet is integrally attached to a base member of an arbitrary shape (for example, a flat plate shape) or a housing of an electronic device or the like. Alternatively, the substrate may be configured by pasting or the like.

  Furthermore, the shape of the base body 40 as viewed in the front-rear direction (front view) is not particularly limited, but since the shape of the display screen 21a of the display 21 is often rectangular, it is rectangular from the viewpoint of enhancing versatility. Is preferred. Therefore, when the shape of the display 21 is different from the rectangular shape, the technique according to the present disclosure is preferably matched to the shape of the display 21. Further, for example, from the viewpoint of improving the ease of attachment, some corners of the rectangular base body 40 may be rounded or notched. Furthermore, the base body 40 may have another shape such as a polygonal shape that is a pentagon or more, or a circular shape. The same applies to the shape of the conductive layer 41 to be described later. From the viewpoint of enhancing versatility, the shape is preferably rectangular, and is preferably matched to the shape of the display screen 21a of the display 21.

  The base 40 is preferably made of an insulating material from the viewpoint of preventing a short circuit due to contact between the other member and the conductive layer 41. The material of the base 40 is not particularly limited as long as it is a substance having insulating properties.

  The surface of the base body 40 includes a detection region Rd including a central portion of the base body 40 and a wiring region Rw surrounding the detection region Rd. In FIG. 2, since the electrode E is provided on the side of the conductive layer 41, the formation range of the conductive layer 41 and the range of the detection region Rd are substantially the same. However, the position where the electrode E is provided may not be on the side of the conductive layer 41. When the electrode E is provided inwardly away from the side of the conductive layer 41, the formation range of the conductive layer 41, The range of the detection region Rd may be different.

  FIG. 2 shows an example in which the wiring region Rw surrounds (encloses) the conductive layer 41, and the conductive layer 41 is not formed in the wiring region Rw. Thus, by not forming the conductive layer 41 in the wiring region Rw, the parasitic capacitance generated between the conductive layer 41 and the wiring 42 can be reduced, and the generation of noise in the position detection operation can be suppressed. Can do.

  Note that the shape of the wiring region Rw is not limited to the mode of FIG. 2, and the wiring region Rw only needs to be provided around the detection region Rd. Specifically, for example, when the base body 40 is rectangular and the detection region Rd is also rectangular, the wiring region Rw is (1) U-shaped (provided around the three sides of the detection region Rd). (2) D-shape (provided around two opposing sides of the detection region Rd) and (3) L-shape (provided around two orthogonal sides of the detection region Rd) It may be. However, since it is preferable from the viewpoint of improving the detection accuracy of the touch position TP that the electrode E that connects the conductive layer 41 and the wiring 42 to be provided on the periphery of the conductive layer 41 at an equal pitch is preferable. Most preferably, it surrounds the detection region Rd. For example, when the detection region Rd (conductive layer 41) is rectangular, the wiring region Rw is most preferably formed in a square shape. By doing so, for example, when the conductive layer 41 is rectangular, the electrodes E can be provided on each side of the conductive layer 41.

  The material of the base body 40 is not limited to an insulating material, and the base body 40 itself is made of the same material as the conductive layer 41 described later, so that the entire base body 40 has a function as the conductive layer 41, and the surface or An insulating layer (for example, an insulating film or an insulating film) may be provided on the back surface. In this case, the electrode E is provided at the side end or corner of the base body 40, and the electrode E and the position detection circuit 5 are connected using wiring such as a lead wire.

-Conductive layer-
The conductive layer 41 is uniformly formed in the detection region Rd on the surface of the base body 40. Thus, the detection region Rd in which the conductive layer 41 is formed corresponds to a region for detecting the touch position. That is, the position detection circuit 5 that detects the touch position TP can be configured to detect the presence or absence of a touch operation on the conductive layer 41.

  The conductive layer 41 contains one or more conductive materials selected from the group consisting of carbon, silver, copper, ITO, ATO, polythiophene (PEDOT), polyaniline, and water-soluble sulfonated polyaniline. Laminated (formed) on top. The carbon is not particularly limited as long as it exhibits electrical conductivity. For example, carbon black, graphene, or carbon nanotube can be used.

(Area of conductive layer)
The detection region Rd preferably includes the entire surface of the display screen 21a of the display 21 from the viewpoint of enabling a touch operation on the entire surface of the display screen 21a. The detection region Rd includes the entire surface of the display screen 21a of the display 21. (1) The area of the detection region Rd is larger than the display screen 21a, and (2) the position as shown in FIG. When the detection device 3 is mounted and fixed on the back side of the display 21, when the display screen 21a is viewed from the front, the entire display screen 21a is within the detection region Rd. It is preferable to be configured as such.

(Resistance value of conductive layer)
The conductive layer 41 preferably has a resistance value R0 of 1 kΩ / □ or more and 10 MΩ / □ or less from the viewpoint of excellent detection accuracy and excellent stability over time. If the resistance value R0 is less than 1 kΩ / □, the differential potential between the applied current and the detected current becomes small, so that the S / N ratio is lowered in the detection of the touch position, which may affect the detection accuracy. Further, when the initial resistance value R0 exceeds 10 MΩ / □, there is a possibility that a delay occurs in detection of the touch position.

(Resistance variation of conductive layer)
The resistance value variation of the conductive layer 41 is preferably 20% or less from the viewpoint of obtaining stability in detection accuracy. Thereby, regardless of the location on the conductive layer 41, the stability is high and good detection accuracy can be realized.

−Wiring−
Four wirings 42 extending along the periphery of the conductive layer 41 are formed in the wiring region Rw on the base body 40. The wiring 42 is used for applying a pulse current to the conductive layer 41 and acquiring a current output from the electrode E. Each of the wirings 42 is connected to the conductive layer 41 via electrodes E that are provided apart from each other. Each wiring 42 is routed along the peripheral edge of the conductive layer 41, collected at one corner on the base 40 (upper right corner in FIG. 2), and position detection mounted on the corner It is connected to the circuit 5.

  The electrode E is provided at the center position of each side of the conductive layer 41. For convenience of explanation, in FIG. 2, of the electrodes E, the electrode provided along the side extending in the vertical direction at the left end of the conductive layer 41 is referred to as a first electrode E1, and the clockwise direction from the first electrode E1. The electrodes provided on each side are referred to as second, third, and fourth electrodes E2, E3, E4, respectively. However, when it does not indicate a specific electrode, it may be simply referred to as an electrode E.

  In addition, the position and number of the electrodes E are not limited to the aspect shown in FIG. For example, the electrodes E may be formed at the four corners of the conductive layer 41, or two or more electrodes E may be formed on one side of the conductive layer 41. That is, it is sufficient that at least two electrodes E are formed on the conductive layer 41 in total, and there is no particular limitation on which side the electrodes E are provided. For example, among the sides of the conductive layer 41, there may be sides where the electrode E is not provided. When the number of electrodes E changes, the number of wirings 42 may be increased or decreased according to the number of electrodes E.

  Specifically, the arrangement of the electrodes E and the number of electrodes can be appropriately changed based on design specifications such as the size of the conductive layer 41 (display size) and detection accuracy. However, the patternless type detection device is characterized in that it is not necessary to provide a large number of electrodes E, as compared with a conventional array type detection device (array type touch panel). Specifically, the number of electrodes E required for the patternless detection device depends on the size of the conductive layer 41 (detection region Rd) and the required accuracy, but the circumference of the conductive layer 41 is less than 1 m. , 20 can provide sufficient detection accuracy. The number of necessary electrodes E may be increased as appropriate in accordance with the size of the display when the size of the display is increased. For example, even when the circumference of the conductive layer 41 is several meters, sufficient detection accuracy can be obtained with about 30 to 40 electrodes E.

-Position detection circuit-
The position detection circuit 5 is realized by, for example, an LSI (Large-Scale Integrated circuit). FIG. 2 shows an example in which the position detection circuit 5 is mounted on the base body 40. Note that the position detection circuit 5 only needs to be configured so that the function of the block shown in FIG. 7 can be realized, and the specific circuit configuration, implementation method, mounting method, and the like are not particularly limited. For example, the position detection circuit 5 may be mounted on a substrate separate from the base body 40. Further, the position detection circuit 5 is not limited to the case where it is realized by an LSI. For example, a circuit may be configured by combining passive elements and active elements and mounted on a printed circuit board or the like.

  FIG. 7 is a block diagram showing a functional configuration of the position detection system according to the present embodiment. As shown in FIG. 7, the position detection circuit 5 includes a signal source 6 for providing a pulse signal as a measurement signal to the electrode E connected to the conductive layer 41, a position information acquisition unit 7, and a calculation unit 8. I have.

  The signal source 6 includes a pulse generator 61 (denoted as PG in FIG. 7) and an analog switch 62 (denoted as AS in FIG. 7). The pulse generator 61 generates a rectangular pulse signal that varies periodically. The analog switch 62 is provided between the pulse generator 61 and each electrode E. Among the four electrodes E1, E2,..., E4, a pulse is applied to an electrode indicated by an electrode selection signal SC1 output from the arithmetic unit 8 described later. It is a switch to give a signal. The electrode selection signal SC1 is a signal indicating two electrodes or four electrodes forming a pair.

  The position information acquisition unit 7 includes a pair of analog switches 71 and 71 having the same configuration (indicated as AS in FIG. 7), a differential amplifier 72, a noise filter 73, and a peak hold circuit 74 (in FIG. 7, P / H And an analog-digital conversion circuit 75 (denoted as ADC in FIG. 1).

  The pair of analog switches 71 receives output signals from the four electrodes E1, E2,..., E4, and is a pair of electrodes to be measured that are selected based on an electrode selection signal SC2 output from the arithmetic unit 8 described later. The output signal of E (hereinafter also referred to as pair electrode E) is passed and output to the input terminal of the differential amplifier 72, respectively. Specifically, one analog switch 71 passes an output signal from one electrode E of the pair electrode E, and the other analog switch 71 passes an output signal from the other electrode E of the pair electrode E. Accordingly, the differential amplifier 72 outputs a differential signal indicating a signal amount difference between output signals from the pair electrode E. The noise filter 73 removes the noise component of the differential signal output from the differential amplifier 72. The peak hold circuit 74 holds the peak voltage of the differential signal from which noise has been removed as an analog signal. The analog-digital conversion circuit 75 converts the peak voltage value and the sign information of the peak voltage into a digital value based on the peak voltage (analog signal). The peak hold circuit 74 is not necessarily required, and the output signal of the noise filter 73 may be directly input to the analog-digital conversion circuit 75. In this case, the analog-digital conversion circuit 75 may be operated in a time division process. Specifically, the analog-to-digital conversion circuit 75 performs digital conversion processing on the analog signal input from the noise filter 73 every predetermined unit time that is time-divided by an appropriate number of samplings. Then, the maximum value is extracted from the digital signal after the digital conversion process, and the peak voltage value and the peak voltage code information based on the maximum value may be recorded.

  The arithmetic unit 8 selects an electrode E that provides a pulse signal from the four electrodes E1, E2,..., E4, and outputs an electrode selection signal SC1 indicating the electrode E to the analog switch 62 of the signal source 6. Further, a pair electrode E to be measured is selected, and an electrode selection signal SC2 indicating the pair electrode E is output to the analog switch 71 of the position information acquisition unit 7. The operation of both switches is controlled by the electrode selection signals SC1 and SC2.

  The electrode selection signal SC1 is a signal indicating two electrodes E or four electrodes E forming a pair arbitrarily selected by the calculation unit 8. Here, there is no particular limitation as to which electrode is selected in what order as the electrode E to which the calculation unit 8 gives the pulse signal. However, when four electrodes are selected, one electrode from each side is selected. Is preferably selected. More preferably, an imaginary line orthogonal to the conductive layer is drawn, electrodes are provided at positions (4 positions) where the imaginary line and the side of the conductive layer 41 overlap, and a signal is given to these electrodes E. preferable.

  The electrode selection signal SC2 is a signal indicating a pair electrode arbitrarily selected from the electrodes selected by the electrode selection signal SC1. Therefore, when the electrode selection signal SC1 is a signal indicating the two electrodes E, the electrode selection signal SC1 and the electrode selection signal SC2 are signals indicating the same electrode.

  Further, the calculation unit 8 determines the position of the indicator (for example, the user's finger) that has approached or contacted the display 21 based on the difference information included in the differential signal (digital value) output from the analog-digital conversion circuit 75. Is obtained by calculation. Here, the difference information refers to all information obtained based on the differential signal. For example, the difference information includes sign information indicating whether the differential signal is a positive voltage signal or a negative voltage signal, voltage difference information indicating the magnitude of the differential signal, and until the differential signal reaches a predetermined voltage. Time information and the like can be included. The calculation unit 8 includes a memory 81 that stores a program for performing the above control and a storage unit 82 that stores a database in which display information, reference coordinate information, and the like described later are registered.

≪Touch position detection operation≫
Next, the touch position detection operation of the position detection system will be described in detail.

<Detection operation (1)>
Here, as shown in FIG. 5, the area of the display screen 21a of the display 21 and the area of the detection region Rd are the same, and the display screen 21a and the detection region Rw according to the fixed state of FIG. The operation of detecting the touch position TP will be described in the case where the positions in the left and right directions (vertical direction and horizontal direction) match.

  In this configuration, if the position detection device 3 and the display 21 are aligned and attached, the position of the display screen 21a and the detection region Rw can be aligned. Therefore, it is possible to detect the touch position TP on the display screen 21a without performing alignment processing (for example, coordinate setting processing or coordinate conversion processing) related to alignment between the two. Such a configuration can be considered, for example, when the position detection device 3 is a dedicated product for a specific electronic device (for example, a specific computer device). Hereinafter, specific description will be given with reference to the drawings.

  In the following description, in order to facilitate understanding, the conductive layer 41 will be described as having a uniform sheet resistance. However, even when the sheet resistance of the conductive layer 41 is partially different, effects similar to those described below can be obtained by performing resistance value correction processing or the like. Although not shown in FIG. 2, each wiring 42 includes an input wiring that connects the output terminal of the position detection circuit 5 that outputs a pulse signal from the pulse generator 61 and the electrode E, and an electrode E. And an output wiring that connects between the input terminal of the position detection circuit 5. Further, it is assumed that a reference resistor R0 is connected between the output terminal of the position detection circuit 5 and each electrode E (input wiring). The same applies to the following “detection operation (2)”.

  FIG. 8 is a flowchart showing an example of the touch position detection operation of the position detection system 1.

  First, as shown in FIG. 1C, when the position detection device 3 is attached and fixed to the back surface of the display 21 and the communication cable 32 a connected to the position detection device 3 is connected to the computer equipment 2, the position detection device. 3 and the CPU 24 of the computer device 2 execute an authentication process (step S0). In the authentication process, basic information related to the position detection operation is exchanged in addition to general mutual authentication (for example, authentication defined in the interface standard). The basic information is information that the CPU 24 acquires from the position detection device 3, for example. This basic information includes information (for example, model number) necessary for determining whether or not the product is a dedicated product, the outer size of the base body 40, the size of the detection region Rd, and the like. Based on this basic information, the CPU 24 determines whether or not it is necessary to perform the above-described alignment process. Here, it is assumed that the CPU 24 determines that the alignment process is unnecessary.

  When the authentication process related to step S0 ends, the computer device 2 and the position detection device 3 each move to the next operation. For example, in the computer device 2, it is assumed that the user operates the input operation unit 22 and activates touch panel software that performs processing based on “touch operation”. Then, CPU24 displays the initial screen of the said software, for example on the display screen 21a of the display 21 (step S21). At this time, in the position detection device 3, the touch position detection process according to step S10 is executed.

-Touch position detection operation (1) (within position detection device)-
Hereinafter, the touch position detection operation in the position detection device 3 will be described in detail with reference to FIG. Here, it is assumed that the electrode selection signal SC1 and the electrode selection signal SC2 are signals indicating the same two electrodes.

  In step S <b> 11, the calculation unit 8 of the position detection circuit 5 (hereinafter simply referred to as the calculation unit 8) determines the first combination of the pair electrodes E. The combination order of the pair electrodes E may be stored in advance in its own circuit (for example, the memory 81), or may be determined based on an instruction from the computer device 2 or an instruction by a user input operation. Here, it is assumed that the first electrode E1 and the second electrode E2 are set as the first pair electrode. That is, the arithmetic unit 8 outputs signals indicating the first and second electrodes E1 and E2 as the electrode selection signals SC1 and SC2.

  In step S12, the pulse signal output from the pulse generator 61 is applied to the first and second electrodes E1, E2 via the analog switch 62. Thereafter, output signals (hereinafter also referred to as position detection signals) from the first and second electrodes E1 and E2 are input to the differential amplifier 72 via the analog switch 71. A differential signal (hereinafter also simply referred to as a differential signal) is output (step S13).

  In step S14, the calculation unit 8 determines whether or not the absolute value of the peak-recorded differential signal (hereinafter also simply referred to as a differential signal) is equal to or greater than a predetermined value. If the absolute value of the differential signal is less than the predetermined value (NO in step S14), the flow returns to step S12, and the pulse signal output from the pulse generator 61 is again applied to the first and second electrodes E and E2. It is done. Here, when there is no touch on the display 21 of the indicator, the absolute value of the differential signal is set so as not to exceed a predetermined value. The operations from S12 to S14 are repeated.

Next, an operation when the user touches the touch position TP of the display will be described. Here, as shown in FIG. 2, it is assumed that the touch position TP is closer to the first electrode E1 than to the second electrode E2. That is, the resistance of the conductive layer 41 between the first electrode E1 and the touch position TP (hereinafter, referred to as a first resistor R1, the resistance value is referred to as R ₁₎ and, the second electrode E2 and the touch position TP It is assumed that a relationship of R ₁ <R ₂ is established with the resistance of the conductive layer 41 between them (hereinafter referred to as the second resistor R ₂ and the resistance value is described as R ₂ ).

In step S12, when a pulse signal is input to the first electrode E1 while the touch position TP is touched, the capacitance CT (capacitance value is C _T ) between the touched indicator and the conductive layer 41 is obtained. The touch position TP is charged up with a voltage corresponding to the time constant with the first resistor R1. This charge-up state is reflected by the first electrode E1, and a reflected signal represented by the following formula (1) is input to one input terminal of the differential amplifier 72.

V ₁ = V _dd (1-exp (−t / R ₁ C _T )) (1)

Here, the capacitance C _T, primarily, the mounting position of the substrate is a value determined depending on the installation conditions such as the thickness of the display. As shown in FIG. 2, a load Z1 having a specific value that differs for each user who touches occurs between the capacitor _CT and the ground. In order to facilitate understanding of the invention, the influence is omitted in this equation. The same applies to the following equations.

Similarly, when a pulse signal is input to the second electrode E2 while the position TP is touched, the other input terminal of the differential amplifier 72 according to the time constant between the capacitor _CT and the second resistor R2. A reflection signal represented by the following formula (2) is input to

V ₂ = V _dd (1-exp (−t / R ₂ C _T )) (2)

  Therefore, the differential amplifier 72 generates a differential signal (difference signal between the expressions (1) and (2)) shown in the following expression (3) and outputs it to the peak hold circuit 74 (step S13).

V _df = V ₁ −V ₂
= V _dd (−exp (−t / R ₁ C _T ) + exp (−t / R ₂ C _T )) (3)

  The peak hold circuit 74 holds the maximum voltage value of Expression (3) as a peak voltage when the differential signal is positive, and holds the minimum voltage value of Expression (3) as the peak voltage when the differential signal is negative. To do.

  In step S14, since the absolute value of the differential signal is equal to or larger than the predetermined value (YES in step S14), the flow proceeds to step S15, and the calculation unit 8 determines the touch position based on the peak voltage value and the sign information of the peak voltage. An operation for obtaining TP is executed. Here, the calculation for obtaining the touch position based on the peak voltage of the differential signal and the arrival time of the peak voltage will be described with reference to FIG.

  Here, a vertical bisector of a virtual straight line IE12 (see the two-dot chain line in FIG. 13) connecting the first electrode E1 and the second electrode E2 is defined as BP12 (see the thick one-dot chain line in the lower right part in FIG. 13). A region closer to the first electrode E1 than the bisector BP12 is referred to as a first region Rd1, and a region closer to the second electrode E2 than the vertical bisector BP12 is referred to as a second region Rd2. Further, imaginary straight lines extending in parallel with BP12 and arranged at an equal pitch α are drawn in each of the first region Rd1 and the second region Rd2 (see the thin one-dot chain line in the lower right part of FIG. 13). In the following description, for convenience of description, in FIG. 13, a parallel straight line of BP12 in the first region Rd1 is illustrated as BP12 + Kα, and a parallel straight line of BP12 in the first region Rd1 is illustrated as BP12−Kα. K is a natural number (K = 1, 2, 3,...) That increases with distance from BP12. A line group including the virtual bisector BP12 drawn in this way and the virtual straight line BP12 ± Kα extending in parallel with BP12 is referred to as a virtual straight line group BPG, and the virtual straight lines constituting the virtual straight line group BPG are collectively referred to. In this case, a description will be given with reference to BP120.

First, a method for specifying a virtual straight line (BP12 + 3α in FIG. 13) closest to the touch position TP from the virtual straight line BP120 will be described. Since the conductive layer 41 having a uniform sheet resistance value, the imaginary straight line BP120, the ratio of the resistance value _{R 1} of the resistance value _{R 2} and the resistor R1 of the resistor R2 is constant _(R 2 _{/ R} 1 = This is a line indicating a place where the value is a constant value.

In the above equation (3), R1 and R2 are both included in the exponential function, and the maximum voltage value of equation (3) is constant when R2 / R1 is constant. Specifically, since the voltage signal output from each electrode (see the above formulas (1) and (2)) increases as the resistance value increases, the peak value of the voltage signal in each virtual line is the virtual line IE12. It gets lower as you move away from. On the other hand, the differential voltage V _df between the first and second electrodes E1 and E2 is output as substantially the same profile. Therefore, based on the magnitude of the peak value of the differential signal of both electrodes E1 and E2, among the virtual straight lines constituting the virtual straight line group BPG, on which straight line the touch position TP exists or which straight line is the most. It is possible to identify (determine) whether they are close.

  Next, a method for identifying where the touch position TP is on the identified virtual straight line (virtual straight line BP12 + 3α in FIG. 13) will be described.

On each virtual straight line BP120, the distance between the first and second electrodes E1 and E2 and the touch position TP is minimized at the point where the virtual straight line IE12 between the first and second electrodes E1 and E2 intersects. The resistance values R ₁ and R _{2 of} R2 are both minimized. That is, the intersection of each virtual straight line BP120 and the virtual straight line IE12 is a point group having the shortest time to reach the differential peak voltage. Then, as illustrated on the imaginary straight line of BP12-α, the resistance values R ₁ and R ₂ increase as they move away in the direction indicated by the arrows D1 and D2, so that the resistance values R ₁ and R ₂ increase in the direction indicated by the arrows D1 and D2. Depending on the distance, the time to reach the differential peak voltage is delayed. Therefore, based on the time to reach the differential peak voltage, it is possible to identify (determine) where the touch position is on the identified virtual straight line 120.

In this way, the touch position TP can be specified based on the peak voltage of the differential signal between the first and second electrodes E1 and E2 and the arrival time thereof. Therefore, even if the touch position detection process in step S10 is terminated at this time, the touch position TP can be detected with sufficient accuracy. On the other hand, as described above, since the resistance values R ₁ and R _{2 of the} resistors R1 and R2 increase as the touch position TP moves away from the virtual straight line IE12 connecting the measurement electrodes (for example, the electrodes E1 and E2), the touch position There may be a difference in detection accuracy between the case where TP is close to the virtual straight line IE12 and the place far from the virtual straight line IE12. Therefore, by changing the combination of the electrodes E in step S16 in FIG. 9, detection with high accuracy can be performed regardless of the touch position TP. Note that the electrodes E (E1 to E4 in FIG. 13) are preferably arranged at an equal pitch in the circumferential direction of the conductive layer 41 from the viewpoint of realizing position detection with high accuracy regardless of the touch position TP.

  In step S16, the flow after changing the combination of the electrodes E is the same as that described above with respect to steps S11 to S15. Then, when the detection of the temporary touch position is completed for all the measurement electrode combinations, in S18, the touch position TP is determined based on the value of the temporary touch position so far, and the detection process of the touch position TP is ended.

  In the above “touch position detection operation (1)”, the detection of the touch position based on the peak voltage of the differential signal and the arrival time of the peak voltage has been described. However, the touch position TP can be detected using the differential signal. Any method or algorithm may be used as long as it is a method. Specifically, it may be arbitrarily selected according to the required accuracy and the processing capability of the arithmetic unit 8. For example, in the following “touch position detection operation (2)”, an example in which the touch position TP is detected based on the polarity of the differential signal will be described. In the following description, it is assumed that the electrode selection signal SC1 and the electrode selection signal SC2 are signals indicating the same two electrodes.

-Touch position detection operation (2) (within position detection device)-
Here, the difference from the “touch position detection operation (1)” will be mainly described. For example, the operation from step S11 to step S14 is the same as the “touch position detection operation (1)”, and the detailed description thereof is omitted here.

In step S15, the calculation unit 8 determines whether the touch position is in the first region Rd1 or the second region Rd2 based on the sign of the peak voltage (see FIG. 10B). Since the resistance values R ₁ and R ₂ of the first and second resistors R ₁ and R ₂ are values proportional to the distance between the touch position and the electrode, the relationship of R ₁ <R ₂ is established, and the peak voltage ( The sign in FIG. 10B is “+”. Therefore, the calculation unit 8 can determine that the touch position TP is in the first region Rd1, and uses this coordinate position as a temporary coordinate position.

  Next, in step S16, it is determined whether or not the combination of the pair electrodes E is to be changed. For example, when electrode combination rules such as the order of changing the combination of the pair electrodes E, the number of combinations, and the number of repetitions are stored in the memory 81, the determination is made based on the electrode combination rules. Specifically, if not all combinations of predetermined pair electrodes E have been completed (YES in step S16), the process proceeds to step S17, and the combination of pair electrodes E is changed. Here, it is assumed that the calculation unit 8 selects the first electrode E1 and the fourth electrode E4 as a pair electrode. Then, the calculation unit 8 draws a vertical bisector BP14 (see a one-dot chain line rising to the right in FIG. 2) of a virtual straight line (not shown) that connects the first electrode E1 and the fourth electrode E4, and bisects the vertical bisector. A region closer to the first electrode E1 than the line BP14 is referred to as a third region Rd3, and a region closer to the fourth electrode E4 than the vertical bisector BP14 is referred to as a fourth region Rd4.

  Similarly to the previous step, after steps S12 to S14 are executed, the calculation unit 8 can determine in step S15 that the touch position TP is in the third region Rd3 based on the sign of the peak voltage. That is, the calculation unit 8 can determine that the temporary touch position is in the overlapping portion (the region indicated by the hatched line in FIG. 3) between the first region Rd1 and the third region Rd3 based on the above two measurements. As described above, the detection accuracy of the temporary touch position can be increased by repeatedly executing the flow from S12 to S17. The flow from S12 to S15 is performed, for example, by changing the combination of the electrodes constituting the pair electrode every period of 5 ms. Accordingly, the calculation unit 8 can generally detect temporary touch positions for several hundred combinations of the pair electrodes E as the total number of times including the number of repetitions until the touch position TP of the indicator changes.

  When the number of combinations of the paired electrodes E reaches a predetermined number (NO in step S16), the calculation unit 8 determines the final touch position TP based on the temporary touch positions calculated so far. Is determined (step S18), and the detection process of the touch position TP is terminated.

  After the touch position detection processing is completed, the processing returns to FIG. 8, and when the detection operation of the touch position TP of the position detection device 3 is completed, the calculation unit 8 performs the touch indicating the touch position TP determined for the CPU 24 of the computer device 2. Output position signal.

  In step S22, the CPU 24 that has received the touch position signal compares the touch position TP indicated by the touch position signal with the display screen 21a displayed on the display 21 in step S21, and touches the touch position on the display screen 21a. The process which concerns on is performed. For example, when the selection screen is displayed in step S21, the CPU 24 displays the selection result related to the touch operation on the display screen 21a of the display 21 (step S23).

-Touch position detection operation (3) (within position detection device)-
Next, the touch position detection operation when the electrode selection signal SC1 is a signal indicating four electrodes and the electrode selection signal SC2 is a signal indicating two electrodes will be described. The basic operation flow is as shown in FIG. 9 (similar to “touch position detection operation (1)”). Here, the difference from “touch position detection operation (1)” is mainly described. explain.

  In step S11, the calculation unit 8 determines a combination of the four electrodes E that are initially set as the electrode selection signal SC1. When the number of electrodes E provided on the conductive layer 41 is four as shown in FIG. 2, the arithmetic unit 8 outputs a signal indicating the four electrodes E1 to E4 as the electrode selection signal SC1. Note that the combination of the first four electrodes E when the number of the electrodes E provided on the conductive layer 41 is five or more may be determined in the same manner as the “touch position detection operation (1)”.

  Furthermore, the calculating part 8 determines the combination of the pair electrode E initially set as electrode selection signal SC1. Here, it is assumed that the first electrode E1 and the second electrode E2 are set as the first pair electrode E. That is, the calculation unit 8 outputs signals indicating the first and second electrodes E1 and E2 as the electrode selection signal SC2.

  In step S <b> 12, the pulse signal output from the pulse generator 61 is given to the first to fourth electrodes E <b> 1 to E <b> 4 via the analog switch 62. At this time, the same pulse signal is given to the pair electrode E (here, the first electrode E1 and the second electrode E2), and the other electrode E (here, the third electrode E3 and the fourth electrode E4) Provide another pulse signal. By doing so, detection position specificity increases and the effect of a sensitivity improvement is acquired. However, the same pulse signal may be given to the first to fourth electrodes E1 to E4.

  The operations in steps S13 to S16 are the same as the “touch position detection operation (1)”. The temporary touch position is detected in step S15 by, for example, preparing a corresponding lookup table (for example, six types of tables) for each combination of the pair electrodes E set as the electrode selection signal SC2. Judgment should be made based on the table.

  In step S17, the combination of the electrodes E set by the electrode selection signals SC1 and SC2 is changed. In FIG. 2, since there are four electrodes E provided on the conductive layer 41, the electrode selection signal SC1 is not changed, and only the combination of the pair electrodes E set by the electrode selection signal SC2 is changed. For example, as the combination of the pair electrodes E, all electrode combinations (six types) are sequentially selected. However, the order of changing the combination of the pair electrodes E, the number of combinations, the number of repetitions, and the like can be arbitrarily set. The flow (loop processing) of steps S11 to S17 after the setting change is the same as the above description and the “touch position detection operation (1)”, and the detailed description thereof is omitted here.

  When the number of combinations of the paired electrodes E reaches a predetermined number (NO in step S16), the calculation unit 8 determines the final touch position TP based on the temporary touch positions calculated so far. Is determined (step S18), and the detection process of the touch position TP is terminated. The flow after the end of the touch position detection process (see FIG. 8) is the same as “Touch position detection operation (1)” and “other embodiments” described later, and detailed description thereof is omitted here. To do.

<Detection operation (2)>
Here, as shown in FIG. 6, the detection operation of the touch position TP when the detection area of the position detection unit is slightly wider than the display screen of the display will be described. Specifically, the detection region Rd has a protruding region Re having a uniform width in the vertical and horizontal directions with respect to the display screen 21a of the display 21. Note that the amount of protrusion of the protrusion region Re does not have to be equal on each side. However, from the viewpoint of operating the entire display screen 21a as a touch panel, the detection region Rd preferably includes the entire display screen 21a in the fixed state of FIG. 1 (c). It becomes easy to install in such an inclusion state.

  The configuration as shown in FIG. 6 has an advantage that versatility can be improved. For example, even with a laptop computer of the same size, the size of the display screen may differ slightly from manufacturer to manufacturer. Therefore, as shown in FIG. 6, by setting the detection region Rd wider than the size of the display screen 21a, the difference in size between the two can be absorbed.

  Hereinafter, a specific description will be given with reference to FIGS. 6 and 11. Although not shown in FIG. 11, the “authentication process” according to step S0 in FIG. 8 is also executed in this aspect. As a result of step S0, the following description will be given here assuming that the CPU 24 determines that the alignment process is necessary.

-Reference coordinate setting (positioning process)-
In step S <b> 41, the CPU 24 performs control to display the marker MK as an identifier on the display 21 and to display a message or the like that prompts the marker MK to be touched on the message area Rm on the display 21. Under the control of the CPU 24, a marker MK and a message are displayed on the display 21 (step S42). For example, as shown in FIG. 6, the markers MK are displayed at the four corners of the display screen, and a message (for example, “touch the marker at the upper left of the screen”) is displayed. In this manner, the user is prompted to touch the marker MK1 (see FIG. 6) at the upper left of the screen. Note that the display order, display mode, and the like of the marker MK are not particularly limited as long as the CPU 24 can grasp which marker is to be touched. For example, the display of the message in the message area Rm may be omitted, and only the marker MK1 may blink to prompt the user to touch. Moreover, it is not necessary to display the marker MK at all four corners. For example, if the markers MK are displayed at least at the two corners facing in the diagonal direction, sufficiently accurate alignment can be performed. In FIG. 6, the markers are MK1, MK2, MK3, and MK4 in the clockwise order from the upper left of the screen. However, when it does not indicate a specific marker, it may be simply referred to as a marker MK.

  Next, in step S <b> 43, the CPU 24 transmits display information to the calculation unit 8. Display information includes, for example, shape information of the display 21 (external shape and size of the display 21, presence / absence of unevenness on the back surface), display screen information (for example, shape and size of the display screen 21a, display screen 21a in the display 21) ), Marker display information related to marker display (for example, display coordinates of the marker MK in the display screen 21a, display order of the marker MK, display time of the marker MK, etc.).

  The calculation unit 8 that has received the display information performs a process related to “reference coordinate setting” in step S30. Hereinafter, a detailed description will be given with reference to FIG.

  In step S <b> 31, the calculation unit 8 refers to the display information received from the CPU 24 and sets a touch estimation region Rt indicating which part of the conductive layer 41 is touched first. For example, when the center of the detection area Rd coincides with the center of the display screen 21a, a fan-shaped area centering on the position on the detection area Rd corresponding to the display position of the marker MK is set as the touch estimation area Rt. (See FIG. 6). Note that the touch estimation region Rt can be arbitrarily set, and the shape and size of the region are not particularly limited. For example, the touch estimation area Rt may be a rectangular area. In this way, by including the display 21 shape information, display screen information, and marker display information in the display information, the prediction accuracy of the touch estimation region Rt can be increased.

  When the touch is performed by the user, the position detection unit 4 performs a detection operation of the touch position TP (step S32). The specific operation in step S32 is the same as the process in step S10 of FIG. 9, and although detailed description thereof is omitted here, the temporary touch position is calculated while changing the combination of the pair electrodes E, and step S18. Then, the touch position of the indicator on the marker MK on the detection region Rd is calculated.

  When the calculation of the touch position is completed, in S33, the calculation unit 8 determines whether or not the detected touch position is within the estimation region Rt. When the detected touch position is outside the estimation region Rt (NG in step S33), the calculation unit 8 outputs an NG signal indicating that the touch detection to the marker MK has not been normally detected to the CPU 24 ( Step S34). As a result, it is possible to prevent a mounting failure of the position detection device 3 and to detect a failure of the position detection device 3.

  Upon receiving the NG signal, for example, the CPU 24 displays an error in the message area Rm and notifies the user to that effect. In addition to the error notification, other display may be performed. For example, it may be possible to prompt retouching or to slightly change the position of the marker. At this time, the flow on the position detection device 3 side returns to step S32. Even when no NG signal is received, for example, when no signal is received from the position detection device 3 even after a certain period of time, an error is displayed in the message area Rm, and the user is prompted to touch again. May be.

  On the other hand, when the detected touch position is within the estimated region Rt (OK in step S33), the calculation unit 8 outputs an OK signal indicating that the touch detection to the marker MK has been normally performed to the CPU 24. Output (step S35).

  Upon receiving the OK signal, the CPU 24 changes the display position of the marker, displays a comment prompting the user to touch the newly displayed marker (for example, the marker MK2 in the upper right of the screen), or makes a sound. Inform the user that the new marker MK has been displayed. At this time, the flow on the position detection device 3 side proceeds to step S36, and determines whether or not the next marker MK is displayed based on the display information. That is, it is determined whether the reference coordinate setting process is completed.

  When the next marker is displayed (NO in step S36), the calculation unit 8 changes the position of the marker to be referred to in step S37, and the flow returns to step S32. For example, when the marker MK2 is displayed after the marker MK1 on the CPU 24, the estimated region Rt is moved to a position centered on the marker MK2.

  In this way, the processing from step S32 to S37 is repeated until all the markers are displayed. When the reference coordinate setting process is completed (YES in step S36), that is, when the display of all the markers MK is completed, the calculation unit 8 registers the calculated reference coordinates in the database of the storage unit 82. The reference coordinates are coordinates serving as a reference for converting a position on the detection region Rd to a position on the display screen 21a. At this time, the CPU 24 can determine, for example, that the reference coordinate setting process in the calculation unit 8 has been completed by receiving an OK signal of the marker (for example, the marker MK4) to be displayed last.

  CPU24 deletes the display of the marker MK and the message of the display screen 21a after the process of the calculating part 8 is complete | finished, for example, displays the initial screen of the software for touchscreens (step S21). Further, in the position detection device, the touch position detection process is started (see FIG. 9), similarly to the “detection operation (1)”.

  In step S <b> 10 </ b> A, the calculation unit 8 detects the touch position TP on the detection region Rd as in the “detection operation (1)”. When the detection of the touch position TP ends, the calculation unit 8 performs a conversion process of the touch position TP using the reference coordinates registered in the database of the storage unit 82 (step S39). Specifically, based on the touch position TP on the detection region Rd and the reference coordinates, a touch coordinate signal indicating the touch position TP on the display screen 21a of the display 21 is generated and transmitted to the CPU 24.

  The CPU 24 that has received the touch coordinate signal compares the touch position TP indicated by the touch coordinate signal with the screen displayed on the display 21 in step S21, and processing necessary when the touch position TP is operated on the screen. Execute. For example, when the selection screen is displayed on the display 21 in step S21, the CPU 24 displays the selection result on the display screen 21a of the display 21 (steps S22 and S23).

  As described above, according to the present embodiment, the position detection device 3 is mounted and fixed on the back side of the display 21 by the mounting mechanism 31 so that the display screen 21a and the detection region Rd face each other. Thereby, when the indicator touches the display screen 21a, the position detection circuit 5 can detect the touch position based on the difference information of the output signals from the conductive layer 41. Therefore, even if the computer device 2 (display 21) does not have a touch panel function or has a touch panel that does not function normally, a touch panel function is added to the computer device 2 (display 21) afterwards. be able to.

  Further, by performing an alignment process such as “setting of reference coordinates”, the position of the display screen 21a of the display 21 and the position of the detection region Rd are not the same in the mounting and fixing state of FIG. In addition, even if the relative positions differ for each attachment, the touch panel function can be effectively functioned.

  Note that the alignment process between the display screen 21a and the detection area Rw is not limited to the “reference coordinate setting” shown in the “detection operation (2)”, for example, a conversion coefficient relating to the conversion of the touch position is registered. A conversion table may be created, and a touch coordinate signal may be generated based on the conversion table. Alternatively, the detection result of the touch position of the marker MK may be transmitted to the CPU 24 as it is, and coordinate conversion or touch position correction processing may be performed in the CPU 24. In addition, the touch position conversion processing and correction processing by the calculation unit 8 or the CPU 24 may be executed based on the movement locus, movement amount, movement speed, and the like from the existing touch position.

<Detection operation (3)>
Although not shown, the touch position TP can be detected even when the detection area of the position detection unit is narrower than the display screen of the display. Specifically, for example, whether the plurality of position detection devices 3 or the plurality of position detection units 4 are arranged side by side in the direction along the surface of the display 21, and the detection area Rd has the same size as the display screen 21 a of the display 21. It should be slightly wider. In this case, what is necessary is just to set the position detection coordinate of each position detection apparatus 3 according to the arrangement place of the said several position detection apparatus 3 (multiple position detection part 4). The specific position detection operation is the same as the above-described “detection operation (1)” or “detection operation (2)”, and detailed description thereof is omitted here. Similarly, the mounting and fixing method of the position detection device 3 is the same as the content described in the “mounting mechanism”, and detailed description thereof is omitted here.

<Other embodiments>
In the above-described embodiment, the detection area is divided using the vertical bisector connecting the pair of electrodes E as a boundary, and the touch position is detected based on the overlapping area. The touch position may be detected with. For example, a touch panel is divided into a plurality of detection areas, and a lookup table (not shown) that lists standard difference information indicating standard difference information when each divided area is touched is prepared. The touch position may be determined based on the up table.

  By using such standard difference information, the touch position detection accuracy can be improved. Specifically, high definition can be realized by increasing the number of divided areas of the detection area.

  Further, the detection accuracy can be improved by correcting the lookup table or using a plurality of lookup tables. Specifically, since the touch capacitance varies among individuals, a lookup table prepared in advance is not always suitable. Therefore, it is possible to improve the accuracy of detecting the touch position by correcting the lookup table or referring to the optimum table among a plurality of lookup tables.

  Furthermore, the detection accuracy of the touch position TP may be improved by performing a majority process based on the detection result of the temporary touch position when the combination of the pair electrodes E is changed. Specifically, for example, when the detection region Rd has a rectangular shape and N electrodes (N is an integer set arbitrarily) are provided on each side, the number PN of electrode combinations is expressed by the following formula ( As shown in 4).

  PN = 4N × 3N / 2 (4)

  In the above equation (4), the combination of the pair electrodes E on the same side is not sensitive, and thus is excluded from the majority process. In other words, the above formula (4) sets the majority of all electrode combinations when one electrode of the pair electrodes E is arbitrarily selected and the other electrode is selected from a side different from the one electrode. The case is illustrated, and when N = 3, the number of combinations is 54. In the majority decision process, for example, a temporary touch position may be detected for each of the 54 electrode combinations, and a position having the highest degree of overlap may be specified as the touch position from the temporary touch positions. In addition, for example, multiple simultaneous touches are detected by arranging the positions extracted as temporary touch positions in the descending order of the degree of overlap and determining whether or not each overlap number exceeds a predetermined threshold. It is also possible to do.

  In the correction of the lookup table, when the marker position is touched in the “reference coordinate setting” process, the lookup table may be corrected based on the difference information related to the touch operation. . This is because the CPU 24 displays the marker MK on the display 21 and makes the user touch the marker MK, so that correction based on the position of the marker MK can be performed. Accordingly, it is possible to perform a lookup table correction process together with “setting of reference coordinates”, and it is possible to increase the detection accuracy of the touch panel while reducing the user's trouble.

  Further, the technology according to the present disclosure can also cope with so-called hovering detection. The touch capacitance is inversely proportional to the square of the vertical distance between the indicator (for example, a finger or a stylus pen) and the position detection unit 4. Therefore, the distance between the indicator and the position detection unit 4 can be calculated based on the magnitude of the peak voltage of the differential signal, and in combination with the detection method of the touch position TP described so far, the hovering can be performed. Detection is possible. In hovering detection, when it is determined that the touch capacitance is small due to the large vertical distance between the indicator and the position detection unit 4, the sensitivity is increased by increasing the detection magnification. The touch position may be detected by. More specifically, sampling is repeatedly performed, and when the peak value does not increase, the calculation unit 8 may increase the detection magnification. Thereafter, when the peak value increases, the calculation unit 8 may be dynamically changed so as to return to the original detection accuracy. Furthermore, the determination can be made more reliable by determining the number of repeated samplings.

  Moreover, in said embodiment, the display 21 does not have a touch panel function, and it demonstrates that a touch panel function can be added afterward by applying the position detection system which concerns on the said embodiment to such a display. did. The position detection system according to the present disclosure can be applied to a display that originally has a touch panel function. For example, when a display panel having a touch panel function or a position detection function cannot be used due to failure or damage, the touch panel function can be supplemented by the position detection system 1 of the present invention.

  In addition, the electrode selection signal SC1 is a signal indicating two electrodes or four electrodes forming a pair, but is not limited thereto. For example, when the shape of the conductive layer 41 is a polygonal shape other than a rectangular shape or a circular shape, the same effect as in this embodiment can be obtained even if the number of electrodes selected by the calculation unit 8 is other than two or four. May be obtained.

  Moreover, although the said embodiment has shown the example in which the pair electrode E used as a measuring object is selected from the electrode E to which the measurement signal (pulse signal) was given, the electrode to which the pair electrode E gives the measurement signal E may not be included. For example, a signal supply electrode for supplying a measurement signal and a signal reception electrode for receiving a measurement signal are separated, and the corresponding signal supply electrode and signal reception electrode are paired, and the counter electrodes are arranged close to each other. Alternatively, they may be arranged slightly apart from each other, and the same effect as in the above embodiment can be obtained.

  Moreover, in the said embodiment, although the signal source 6 shall give a measurement signal to the conductive layer 41 via the electrode E connected to the conductive layer 41, it is not limited to this. For example, the signal source 6 may provide a measurement signal directly or indirectly to the conductive layer 41 from a different location from the electrode E.

  Specifically, for example, the signal source 6 may directly apply a measurement signal to the conductive layer 41 from one or a plurality of nodes (contact points) different from the electrode E of the conductive layer 41.

  Further, the signal source 6 may give a measurement signal to the conductive layer 41 via a load or a component having a capacitive component. For example, a wiring area for signal input or a sheet-like signal input area is disposed to face the conductive layer 41 at a predetermined interval in the thickness direction, and the signal source 6 is connected to the wiring area or signal. You may make it give a measurement signal to the conductive layer 41 indirectly via an input area. At this time, an insulator such as air or a substrate is preferably interposed between the conductive layer 41 and the wiring region or the signal input region. Also in this case, the configuration and operation of the position information acquisition unit 7 may be the same as those in the above embodiment, and the same effects as those in the above embodiment can be obtained.

  The present invention is extremely useful because a touch panel function can be added to the image display device afterwards.

DESCRIPTION OF SYMBOLS 1 Position detection system 3 Position detection apparatus 4 Position detection part 6 Signal source 8 Calculation part (detection side calculation part)
21 Display (image display device)
21a Display screen 23 Communication unit (display side communication unit)
24 CPU (display side calculation unit)
31 Mounting mechanism 32 Communication unit (detection side communication unit)
41 Conductive layer E electrode Rd detection area MK marker (identifier)

Claims (12)

An image display device provided with a display screen;
A position detection device that is detachably attached and fixed to the back surface of the image display device and detects the position of the indicator that touches the display screen;
The image display device includes:
A display-side communication unit configured to be able to communicate with the position detection device;
The position detection device includes:
A conductive layer arranged opposite to the display screen and for detecting the position of the indicator touching the display screen;
A plurality of electrodes, spaced apart from each other, each connected to the conductive layer;
A signal source for providing a measurement signal to the conductive layer;
Based on difference information of output signals output from a pair of electrodes selected from the plurality of electrodes, a detection side calculation unit that calculates the position of the indicator touching the display screen;
A position detection system comprising: a detection side communication unit that transmits position information of the indicator calculated by the detection side calculation unit to a display side communication unit of the image display device. The position detection system according to claim 1, wherein the signal source provides a measurement signal to the conductive layer through an electrode selected from the plurality of electrodes. Two or four electrodes are provided with the measurement signal,
The position detection system according to claim 2, wherein the detection side calculation unit selects the pair electrode from the electrodes to which the measurement signal is given. The position detection device has a table in which standard difference information according to the position of the indicator is registered for each combination of electrodes paired among the plurality of electrodes.
The detection side calculation unit calculates a position of an indicator touching the display screen based on a result of comparing difference information of the output signal and standard difference information of the table. Or the position detection system according to 2. The image display device includes a display-side arithmetic unit that displays an identifier on the display screen and transmits position information of the identifier to the position detection device via the display-side communication unit,
When the detection side calculation unit detects a first touch when the position of the identifier on the display screen is touched, the detection side calculation unit corrects the standard difference information of the table based on the difference information of the output signal related to the first touch. And setting position detection coordinates based on the position of the first touch and the position information of the identifier,
The position detection system according to claim 4, wherein the detection-side communication unit transmits position information of the indicator on the position detection coordinates to the display-side communication unit. An image display device provided with a display screen, and detachably attached and fixed to the back side of the image display device, and disposed opposite the back surface of the display screen to detect the position of the indicator touching the display screen A position detection method of a position detection system comprising a position detection device having a detection region made of a conductive layer for performing,
A reference transmission step of displaying an identifier on the display screen by the image display device and transmitting position information of the identifier to the position detection device;
A first touch when the position of the identifier on the display screen is touched is detected by the position detection device, and position detection coordinates are determined based on the first touch position related to the first touch and the position information of the identifier. A coordinate setting step to be set;
After the coordinate setting, a second touch when the display screen is touched is detected by the position detection device, and a second touch position related to the second touch on the position detection coordinates set in the coordinate setting step is determined. A position detection method comprising: a touch position detection step of outputting to the image display device. The display screen is rectangular,
7. The reference transmitting step, wherein the identifier is displayed by at least two corners opposed to each other in a diagonal direction among the four corners of the display screen by the image display device. The position detection method described. The position detection method according to claim 6 or 7, wherein in the reference transmission step, the image display device transmits size information of the display screen to the position detection device. In the coordinate setting step, the position detection device sets a touch prediction area having a predetermined area in the detection area based on the size information of the display screen and the position information of the identifier, and When it is detected that a touch is made inside the touch prediction area, the position detection coordinates are set, while when it is detected that the first touch is made outside the touch prediction area, the position detection coordinates are set. The position detection method according to claim 8, wherein a notification to that effect is sent to the image display device without setting the value. In the coordinate setting step, if the first touch is not detected even after a predetermined time has elapsed after receiving the position information of the identifier from the image display device by the position detection device, the image display device indicates that. The position detection method according to claim 6, wherein notification is performed. A position detection device for detecting the position of an indicator touching the display screen, which is detachably attached and fixed to the back surface of the image display device provided with a display screen on the front surface,
A conductive layer for detecting the position of the indicator touching the display screen;
A plurality of electrodes, spaced apart from each other, each connected to the conductive layer;
A signal source for providing a measurement signal to the conductive layer;
Based on difference information of output signals output from a pair of electrodes selected from the plurality of electrodes, a calculation unit that calculates the position of the indicator touching the display screen;
A communication unit that outputs position information of the indicator calculated by the calculation unit, and a position detection unit,
And an attachment mechanism that is provided integrally with the position detection unit and detachably attaches the position detection unit to the image display device so that the conductive layer is disposed along the back surface of the display screen. A position detection device characterized by the above. The position detection device according to claim 11, wherein the signal source provides a measurement signal to the conductive layer through an electrode selected from the plurality of electrodes.

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