JP7007984B2 - Position detection system, position detection method and position detection device - Google Patents

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 provided with a capacitive touch panel on the front of the display screen. With such a display, it has become possible to operate a computer device, input characters, etc. by bringing an indicator such as a finger into contact with the display on which an image is displayed without operating an operation unit such as a mouse. (For example, Patent Document 1).

Further, 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 positions are calculated based on the output voltage of the detection circuits.

Japanese Unexamined Patent Publication No. 2012-13867 International Publication WO 2013/153609 Pamphlet

In modern computer equipment, the operating system and various software are designed to be compatible with touch operations.

However, many stationary computer devices called desktop personal computers and laptop computer devices called laptop computers do not have a touch panel function on the display. For example, an old laptop computer has a problem that some functions of the software cannot be used because it does not have a touch panel even though it can be used sufficiently. In general, it is difficult to replace the display part of a notebook computer with a touch panel in terms of design, so there is a problem that a set of notebook computers must be replaced in order to operate the touch panel. Further, even if the touch panel function is provided, if the touch panel fails, the touch operation may not be possible even if there is no problem in displaying the image on the display.

Therefore, the present invention provides a position detection system capable of adding a touch panel function to the image display device after the fact even if the image display device has a touch panel that does not have the 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 detachably attached and fixed is provided on the back side of the image display device, and the position information detected by the position detection device is displayed on the image display device. I tried to send it to.

That is, the position detection system according to one aspect of the present invention is detachably attached and fixed to the image display device provided with the display screen and the back surface of the image display device, and the position of the indicator touching the display screen is determined. It is equipped with a position detection device for detection. The image display device has a display-side communication unit configured to enable communication with the position detection device. Further, the position detecting device is arranged so as to face the display screen and is arranged apart from each other with a conductive layer for detecting the position of the indicator touching the display screen, and each of the conductive layers is arranged. Difference information between a plurality of electrodes connected to, a signal source that gives a measurement signal to a pair of electrodes selected from the plurality of electrodes, and an output signal output from the pair of electrodes to which the measurement signal is given. The position information of the indicator calculated by the detection side calculation unit and the detection side calculation unit that calculates the position of the indicator close to the conductive layer are transmitted to the display side communication unit of the image display device. It is characterized in that it is provided with a detection side communication unit.

Here, "image" is a concept including a still image and a moving image.

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

The position detection system according to the above aspect is configured to detect the position of the indicator touching 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. Further, the touch position of the indicator to the display screen detected by the position detection device is transmitted from the detection side communication unit to the display side communication unit. As a result, the image display device can execute the process 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 if the image display device does not have the touch panel function or the touch panel (image display device) does not function normally, the touch panel function can be added to the image display device after the fact.

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, the touch panel function is added to the image display device after the fact. Can be done.

It is a schematic block diagram of a position detection system. It is a front view which shows the schematic structure of the position detection device. FIG. 3 is a schematic cross-sectional view taken along the line III-III of FIG. 2 is a schematic cross-sectional view taken along the line IV-IV of FIG. 2. It is a schematic diagram which shows an example of the relationship of the position and the 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 of the position and the size of the display screen of a display, and the detection area of a position detection part. It is a block diagram which shows the functional structure of a position detection system. It is a flow chart which shows an example of the touch position detection operation of a position detection system. It is a flow chart which shows the detection operation of the touch position of a position detection apparatus. It is a figure which showed an example of the signal waveform when the point TP of FIG. 2 is touched. It is a flow diagram which shows the other example of the touch position detection operation of a position detection system. It is a flow chart which shows the setting operation 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 preferred embodiments is merely exemplary and is not intended to limit the invention, its applications or its uses.

As shown in FIG. 1, the position detection system 1 according to the present embodiment includes a computer device 2 provided with 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, the surface on which the display screen 21a is displayed is the front surface, and the surface facing the front surface is the back surface. Further, the front side is referred to as a front side and the back side is referred to as a back side, and 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 comes into contact with the display screen 21a of the display 21. In the present embodiment, the touch is 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). Is a concept that includes. Further, the touch of the indicator to the display 21 is simply referred to as "touching". Further, when the indicator touches the display 21, the touched position 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-type computer device 2 provided with a horizontally long display 21 having no 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 stores an input operation unit 22 such as a keyboard and a mouse, a communication unit 23 (see FIG. 7) configured to enable communication such as USB communication, a CPU 24 (see FIG. 7), a hard disk drive, and the like. It is provided with a unit 25 (see FIG. 7).

The communication unit 23 is configured to enable bidirectional communication with the communication unit 32 (see FIG. 7) of the position detection device 3 described later. The communication method related to the two-way communication is not particularly limited, and may be wireless communication, wired communication, or both. FIG. 1 shows an example in which a computer device 2 and a 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 device 2 will be described as an example of the electronic device, but the technique according to the present disclosure can be applied if at least an image display device for displaying an image is included in the display screen. .. For example, electronic devices including image display devices include televisions, smartphones, tablets, electronic book readers, electronic music players, mobile phones, and the like. Further, 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, but the computer main body 20 and the display 21 are physically separated. May be 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 thereof, and specifically, displays image information such as software executed by a computer device. Images include still images and moving images. The display form, display principle, display method, etc. 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 element display, a particle transfer type electronic paper, and the like. Further, the display 21 may include a backlight, a light reflecting plate, a light reflecting sheet, and the like.

The thickness of the display 21 (front and back directions) is not particularly limited, but is preferably 5 cm or less from the viewpoint of ensuring stable detection accuracy of the touch position TP. Further, 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 mounted and the position stability after mounting 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 arranged behind an image display device that displays a display screen that functions as a touch panel. FIG. 1C 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 to 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 area Rd for detecting the position of the indicator touching the display screen 21a of the display 21, and a position detection unit. A mounting mechanism 31 for mounting and fixing the 4 to the back side of the display 21 and a communication unit 32 for bidirectional communication with a computer device are provided.

Hereinafter, each configuration of the position detection device will be described in detail.

<Mounting mechanism>
The mounting mechanism 31 may be configured so that the position detection device 3 can be detachably mounted and fixed on the back surface of the display 21, and the specific mounting structure and mounting method thereof are not particularly limited. For example, the mounting mechanism 31 may be realized by a hook portion that can be hooked to the peripheral end of the display 21 as shown in FIG. 1 (b) (both sides in the lateral direction of the upper end in FIG. 1 (b)). Further, the mounting mechanism 31 may have a screwing mechanism, and may be configured so that it can be attached by a double-sided tape, an adhesive sheet, or a suction cup. Further, the mounting mechanism 31 may be a rubber band used by hanging around the outer periphery of the display 21, or may be a magnet or the like to be adhered to the back surface of the display 21 when the back surface is made of a magnetic material. good. In addition, in mounting and fixing, those having high attachment / detachment ease and high fixing strength, position stability and adhesion stability at the time of mounting and fixing are more preferable, and the above elements may be combined in order to realize them. For example, by combining the hook portion with a suction cup, an adhesive sheet, or the like, it is possible to improve the fixing strength, the position stability, and the adhesion stability at the time of mounting and fixing.

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

<Position detector>
As shown in FIGS. 2 to 4, the position detection unit 4 includes a substrate 40 having a conductive layer 41 and a wiring 42 formed on its surface, and a position detection circuit 5 mounted on the substrate 40. The external shape and size of the position detection unit 4 (base 40) are not particularly limited, but for example, the position detection unit 4 is configured so that the external dimensions are substantially the same as those of the display 21. This facilitates positioning when the position detection unit 4 is attached and fixed to the display 21.

The position detection unit 4 may be covered with a protective member (not shown) in whole or in part on the outer surface. For example, the entire outer surface of the position detection unit 4 may be covered with a protective member formed of a resin or the like, or specific parts such as a conductive layer, electrodes, and wiring may be protected by the protective member. That is, it is possible to apply a protective member whose design has been appropriately modified in order to enhance the design of the display 21 and to enhance various performances such as durability and weather resistance. The position detection device 3 can detect the touch position even if the entire position detection unit 4 is covered with the protective member.

-Hypokeimenon-
The shape of the substrate 40 is not particularly limited, but is, for example, a rectangular sheet (film or thin plate) or a rectangular flat plate. For example, if the substrate 40 is in the form of a sheet, there is an advantage that the position detection unit 4 can be formed by deforming the substrate 40 according to the shape when the back surface of the display 21 has irregularities or curves. .. For example, if the substrate 40 has a flat plate shape, when the back surface of the display 21 is flat, there is an advantage that the display 21 can be easily mounted and fixed to the back side and the mounting stability is high. The substrate 40 does not have to be made of a single material. For example, a conductive sheet having a conductive layer formed on the front surface or the back surface of an insulating sheet is provided, and the conductive sheet is integrally attached to a base member having an arbitrary shape (for example, a flat plate shape) or a housing such as an electronic device. The substrate may be formed by sticking or pasting.

Further, the shape of the substrate 40 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 preferable. Therefore, when the shape of the display 21 is different from the rectangular shape, it is preferable to match the technique according to the present disclosure with the shape of the display 21. Further, for example, from the viewpoint of improving the ease of attachment, some corners of the rectangular substrate 40 may be rounded or notched. Further, the substrate 40 may have another shape such as a pentagon or more polygonal shape or a circular shape. The same applies to the shape of the conductive layer 41 described later, and from the viewpoint of enhancing versatility, it is preferably rectangular, and it is preferable to match the shape of the display screen 21a of the display 21.

It is preferable to use an insulating material for the substrate 40 from the viewpoint of preventing a short circuit due to contact between the other member and the conductive layer 41. The material of the substrate 40 may be any material having an insulating property, and is not particularly limited.

The surface of the substrate 40 includes a detection region Rd including the central portion of the substrate 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 does not have to be on the side of the conductive layer 41, and when the electrode E is provided inward away from the side of the conductive layer 41, the formation range of the conductive layer 41 and the formation range of the conductive layer 41. The range of the detection area Rd may be different.

FIG. 2 shows an example in which the wiring region Rw surrounds (surrounds) the conductive layer 41, and the conductive layer 41 is not formed in the wiring region Rw. By preventing the conductive layer 41 from being formed in the wiring region Rw in this way, 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 be done.

The shape of the wiring region Rw is not limited to the embodiment shown in FIG. 2, and the wiring region Rw may be provided around the detection region Rd. Specifically, for example, when the substrate 40 is rectangular and the detection region Rd is also rectangular, the wiring region Rw is provided around (1) U-shape (around the three sides of the detection region Rd). (2) D-shaped (provided around two opposite sides of the detection area Rd) and (3) L-shaped (provided around two orthogonal sides of the detection area Rd) It may be. However, it is preferable that electrodes E for connecting the conductive layer 41 and the wiring 42 are provided on the peripheral edge of the conductive layer 41 at equal pitches from the viewpoint of improving the detection accuracy of the touch position TP. Therefore, the wiring region Rw is set. It is most preferable to surround the detection region Rd. For example, when the detection region Rd (conductive layer 41) is rectangular, it is most preferable that the wiring region Rw is formed in a square shape. By doing so, for example, when the conductive layer 41 has a rectangular shape, electrodes E can be provided on each side of the conductive layer 41.

The material of the substrate 40 is not limited to the insulating material, and the substrate 40 itself is made of the same material as the conductive layer 41 described later, so that the entire substrate 40 has a function as the conductive layer 41, and the surface thereof or the surface thereof. 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 portion or the corner portion of the substrate 40, and the electrode E and the position detection circuit 5 are connected by 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 substrate 40. As described above, the detection region Rd on which the conductive layer 41 is formed corresponds to the region for detecting the touch position. That is, the position detection circuit 5 that performs the touch position TP detection process is 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, and the substrate 40 contains. It is laminated (formed) on top. The carbon is not particularly limited as long as it exhibits conductivity, and for example, carbon black, graphene, and carbon nanotubes 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 touch operation on the entire surface of the display screen 21a. The fact that the detection area Rd covers the entire surface of the display screen 21a of the display 21 means that (1) the area of the detection area Rd has an area larger than that of the display screen 21a, and (2) the position is as shown in FIG. 1 (c). When the display screen 21a is viewed from the front in a state where the detection device 3 is attached and fixed to the back side of the display 21, it means that the entire display screen 21a is within the range of the detection area Rd, and the position detection device 3 is used. It is preferable that it is configured in this way.

(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 detection current becomes small, so that the S / N ratio decreases in the detection of the touch position, which may affect the detection accuracy. Further, if the initial resistance value R0 exceeds 10 MΩ / □, a delay may occur in the detection of the touch position.

(Variation of resistance value of conductive layer)
The variation in the resistance value of the conductive layer 41 is preferably 20% or less from the viewpoint of obtaining stability of detection accuracy. As a result, it is possible to realize high stability and good detection accuracy regardless of the location on the conductive layer 41.

-wiring-
In the wiring region Rw on the substrate 40, four wirings 42 extending along the peripheral edge of the conductive layer 41 are formed. 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 wiring 42 is connected to the conductive layer 41 via electrodes E provided apart from each other. Each wiring 42 is routed along the peripheral edge of the conductive layer 41, aggregated in one corner portion on the substrate 40 (upper right corner portion in FIG. 2), and position detection mounted on the corner portion. 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, among 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 the first electrode E1, and the first electrode E1 is in the clockwise order. The electrodes provided on each side are the second, third and fourth electrodes E2, E3 and E4, respectively. However, when it does not refer to a specific electrode, it may be simply described as electrode E.

The position and number of the electrodes E are not limited to the mode 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 on. For example, among the sides of the conductive layer 41, there may be a side on which 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 the design specifications such as the size of the conductive layer 41 (the size of the display) and the detection accuracy. However, the patternless detection device has a feature that it is not necessary to provide a large number of electrodes E as compared with the 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 when the circumference of the conductive layer 41 is less than 1 m. If 20 pieces are used, sufficient detection accuracy can be obtained. When the size of the display becomes large, the number of necessary electrodes E may be appropriately increased according to the size. For example, even when the circumference of the conductive layer 41 is several meters, sufficient detection accuracy can be obtained if there are 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 substrate 40. The position detection circuit 5 may be configured so that the function of the block shown in FIG. 7 can be realized, and the specific circuit configuration, its realization 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 substrate 40. Further, the position detection circuit 5 is not limited to the case where it is realized by an LSI, and for example, a circuit may be configured by combining a passive element and an active element 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 giving 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 has 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 fluctuates periodically. The analog switch 62 is provided between the pulse generator 61 and each electrode E, and has a pulse on the electrode indicated by the electrode selection signal SC1 output from the arithmetic unit 8 described later among the four electrodes E1, E2, ..., E4. It is a switch to give a signal. The electrode selection signal SC1 is a signal indicating two or four electrodes in a pair.

The position information acquisition unit 7 includes a pair of analog switches 71 and 71 (denoted as AS in FIG. 7), a differential amplifier 72, a noise filter 73, and a peak hold circuit 74 (P / H in FIG. 7) having the same configuration. (Notated as) and an analog-to-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 selected based on the 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 through 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. As a result, the differential amplifier 72 outputs a differential signal indicating a signal amount difference of the output signal 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-to-digital conversion circuit 75 converts the peak voltage value and the code information of the peak voltage into digital values based on the peak voltage (analog signal). The peak hold circuit 74 is not always necessary, 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-to-digital conversion circuit 75 may be made to operate in time division processing. Specifically, the analog-to-digital conversion circuit 75 performs digital conversion processing on the analog signal input from the noise filter 73 at predetermined unit times divided by time with an appropriate sampling number. Then, it is preferable to extract the maximum value from the digital signal after the digital conversion process and record the peak voltage value and the sign information of the peak voltage based on the maximum value.

The calculation unit 8 selects an electrode E that gives 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, the pair electrode E to be measured is selected, and the 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 that form a pair arbitrarily selected by the arithmetic unit 8. Here, which electrode is selected by the arithmetic unit 8 as the electrode E for giving the pulse signal in what order is not particularly limited, but when four electrodes are selected, one electrode is selected from each side. It is preferable to select. Further, more preferably, it is preferable to draw orthogonal virtual lines on the conductive layer, provide electrodes at positions (4 locations) where the virtual lines and the sides of the conductive layer 41 overlap, and give a signal to those electrodes E. preferable.

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

Further, the arithmetic unit 8 determines the position of the indicator (for example, the user's finger) that has approached or touched the display 21 based on the difference information included in the differential signal (digital value) output from the analog-to-digital conversion circuit 75. Is calculated by calculation. Here, the difference information refers to all the information obtained based on the differential signal. For example, the difference information includes code 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. It can include time information and the like. Further, the arithmetic unit 8 includes a memory 81 in which a program for performing the above control is stored, and a storage unit 82 in which a database in which display information, reference coordinate information, etc., which will be described later are registered, is stored.

≪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 area Rd are the same, and the display screen 21a and the detection area Rw related to the fixed state of FIG. 1C are above and below. The detection operation of the touch position TP will be described when the positions in the left-right direction (vertical direction and horizontal direction) match.

In this configuration, if the position detection device 3 and the display 21 are aligned and mounted, the positions of the display screen 21a and the detection area Rw can be aligned. Therefore, the touch position TP to the display screen 21a can be detected without performing the alignment process (for example, the coordinate setting process or the coordinate conversion process) related to the alignment between the two. Such a configuration may be considered, for example, when the position detection device 3 is a dedicated product of a specific electronic device (for example, a specific computer device). Hereinafter, a 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, the same effect as described below can be obtained by performing a resistance value correction process or the like. Further, although not shown in FIG. 2, each wiring 42 includes an input wiring connecting between the output terminal of the position detection circuit 5 to which the pulse signal from the pulse generator 61 is output and the electrode E, and the electrode E. It is assumed that the output wiring connecting the device to the input terminal of the position detection circuit 5 is included. Further, it is assumed that the reference resistance 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 description of "detection operation (2)".

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

First, as shown in FIG. 1 (c), when the position detection device 3 is attached and fixed to the back surface of the display 21, and the communication cable 32a connected to the position detection device 3 is connected to the computer device 2, the position detection device 3 is attached. The authentication process is executed between the arithmetic unit 8 of 3 and the CPU 24 of the computer device 2 (step S0). In the authentication process, in addition to general authentication between mutual devices (for example, authentication defined by an interface standard), basic information related to position detection operation is exchanged. The basic information is, for example, information acquired by the CPU 24 from the position detection device 3. This basic information includes information necessary for determining whether or not the product is a dedicated product (for example, model number), the external size of the substrate 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-mentioned alignment process. Here, it is assumed that the CPU 24 determines that the alignment process is unnecessary.

When the authentication process according to step S0 is completed, the computer device 2 and the position detection device 3 each shift to the next operation. For example, in the computer device 2, it is assumed that the user operates the input operation unit 22 to activate the touch panel software that performs processing based on the "touch operation". Then, the CPU 24 causes the display screen 21a of the display 21 to display, for example, the initial screen of the above software (step S21). At this time, the position detection device 3 executes the touch position detection process according to step S10.

-Touch position detection operation (1) (inside the 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 S11, the calculation unit 8 of the position detection circuit 5 (hereinafter, simply referred to as the calculation unit 8) determines the combination of the first pair electrodes E. The combination order of the pair electrodes E may be stored in the own circuit (for example, the memory 81) in advance, or may be determined based on an instruction from the computer device 2 or an instruction by a user's 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 calculation 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 given to the first and second electrodes E1 and E2 via the analog switch 62. After that, 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, and the position detection signal is input from the differential amplifier 72. 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 higher than a predetermined value. When the absolute value of the differential signal is less than a predetermined value (NO in step S14), the flow returns to step S12, and the pulse signal output from the pulse generator 61 is given to the first and second electrodes E and E2 again. Be done. Here, when the indicator does not touch the display 21, the absolute value of the differential signal is set so as not to exceed a predetermined value, so that the step is performed until the display 21 is touched. The operations of S12 to S14 are repeated.

Next, the operation when the user touches the touch position TP of the display will be described. Here, as shown in FIG. 2, 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 the first resistance _R1 and the resistance value is referred to as R1), and the second electrode E2 and the touch position TP. It is assumed that the relationship of R ₁ <R ₂ is established between the resistance of the conductive layer 41 (hereinafter referred to as the second resistance R2 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, a capacitance CT (capacity value is _CT ) 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 the reflected signal represented by the following equation (1) is input to one input terminal of the differential amplifier 72.

V ₁ = V _dd (1-exp (-t / R _1CT )) ... ( ₁ )

Here, the capacitance _CT is a value uniquely determined mainly according to the mounting position of the substrate, the installation conditions such as the thickness of the display, and the like. As shown in FIG. 2, a load Z1 having a specific value different for each user to be touched is generated between the capacitance _CT and the ground. In order to facilitate the understanding of the invention, the influence thereof is omitted in this equation. The same applies to the following formula.

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 depends on the time constant of the capacitance _CT and the second resistor R2. The reflected signal represented by the following equation (2) is input to.

V ₂ = V _dd (1-exp (-t / R _2CT )) ... ( ₂ )

Therefore, in the differential amplifier 72, the differential signal represented by the following equation (3) (the signal of the difference between the equations (1) and (2)) is generated and output to the peak hold circuit 74 (step S13).

V _df = V ₁ -V ₂
= V _dd ( _-exp (-t / R ₁ CT) + exp (-t / R _{2 CT} )) ... (3)

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

In step S14, since the absolute value of the differential signal becomes a predetermined value or more (YES in step S14), the flow proceeds to step S15, and the arithmetic unit 8 touches the touch position based on the peak voltage value and the code information of the peak voltage. Execute the operation to find the TP. Here, the operation of 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, the perpendicular bisector of the virtual straight line IE12 (see the two-point chain line in FIG. 13) connecting the first electrode E1 and the second electrode E2 is defined as BP12 (see the thick single-point chain line in the lower right of FIG. 13), and is vertical. The region closer to the first electrode E1 than the bisector BP12 is referred to as the first region Rd1, and the region closer to the second electrode E2 than the perpendicular bisector BP12 is referred to as the second region Rd2. Further, virtual straight lines extending parallel to BP12 and arranged at equal pitch α intervals are drawn in each of the first region Rd1 and the second region Rd2 (see the thin alternate long and short dash line in FIG. 13). In the following description, for convenience of explanation, FIG. 13 shows the parallel straight line of BP12 in the first region Rd1 as BP12 + Kα and the parallel straight line of BP12 in the first region Rd1 as BP12-Kα. K is a natural number (K = 1, 2, 3, ...) That increases as the distance from BP12 increases. Further, the line group including the perpendicular bisectors BP12 drawn in this way and the virtual straight line BP12 ± Kα extending in parallel with the 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. The case will be described with a reference numeral of BP120.

First, a method of specifying the 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 has a uniform sheet resistance value, the ratio of the resistance value R2 of the resistor _R2 to the resistance value _R1 of the resistor R1 is constant in each virtual straight line BP120 (R ₂ / R ₁ =). It is a line showing the place where it becomes (constant value).

In the above equation (3), both R1 and R2 are included in the exponential function, and the maximum voltage value of the equation (3) becomes constant at a place where R2 / R1 is constant. Specifically, the voltage signal output from each electrode (see the above equations (1) and (2)) has a larger attenuation as the resistance value increases, so that the peak value of the voltage signal in each virtual straight line is the virtual straight line IE12. It becomes 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, which straight line the touch position TP exists on or which straight line is the most among the virtual straight lines constituting the virtual straight line group BPG. It is possible to specify (determine) whether it is close.

Next, a method for specifying where the touch position TP is on the specified 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 _R1 and R2 of _R2 are both the minimum. That is, the intersection of each virtual straight line BP120 and the virtual straight line IE12 is a point cloud in which the time to reach the differential peak voltage is the shortest. Then, as illustrated on the virtual straight line of BP12-α, the resistance values _R1 and _R2 become larger as the distance is increased in the directions indicated by the arrows D1 and D2. Depending on the distance, the time to reach the differential peak voltage becomes slower. Therefore, it is possible to specify (determine) where the touch position is on the specified virtual straight line 120 based on the time when the differential peak voltage is reached.

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 completed at this point, the touch position TP can be detected with sufficient accuracy. On the other hand, as described above, 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 resistance values _R1 and R2 of the resistors R1 and _R2 increase, so that the touch position There may be a difference in the detection accuracy between the case where the 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 of FIG. 9, high-precision detection can be performed regardless of the touch position TP. From the viewpoint of realizing position detection with high accuracy regardless of the touch position TP, the electrodes E (E1 to E4 in FIG. 13) are preferably arranged at equal pitches in the circumferential direction of the conductive layer 41.

In step S16, the flow after changing the combination of the electrodes E is the same as the description regarding steps S11 to S15 so far. Then, when the detection of the temporary touch position for all the combinations of the measurement electrodes is completed, the touch position TP is determined based on the values of the temporary touch position up to that point in S18, and the touch position TP detection process is completed.

In the above "touch position detection operation (1)", the touch position detection based on the peak voltage of the differential signal and the arrival time of the peak voltage has been described, but 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 capacity of the arithmetic unit 8. For example, in the following “touch position detection operation (2)”, an example of detecting the touch position TP 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) (inside the 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 detailed description thereof will be 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 code of the peak voltage (see FIG. 10B). Since the resistance values _R1 and R2 of the first and second resistances R1 and _R2 are proportional to the distance between the touch position and the electrode, the relationship of _R1 < _R2 is established, and the peak voltage ( The reference numeral in FIG. 10B) is “+”. Therefore, the calculation unit 8 can determine that the touch position TP is in the first region Rd1, and sets this coordinate position as the temporary coordinate position.

Next, in step S16, it is determined whether or not to change the combination of the pair electrodes E. For example, when the memory 81 stores the 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, the determination is made based on the electrode combination rules. Specifically, when all the predetermined combinations of the pair electrodes E have not been completed (YES in step S16), the process proceeds to step S17, and the combination of the 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 arithmetic unit 8 draws a perpendicular bisector BP14 (see the one-point chain line rising to the right in FIG. 2) of a virtual straight line (not shown) connecting the first electrode E1 and the fourth electrode E4, and divides the perpendicular bisector into vertical bisectors. The region closer to the first electrode E1 than the line BP14 is referred to as the third region Rd3, and the region closer to the fourth electrode E4 than the perpendicular bisector BP14 is referred to as the fourth region Rd4.

As before, after the steps S12 to S14 are executed, the arithmetic 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, based on the above two measurements, the calculation unit 8 can determine that the temporary touch position is in the overlapping portion (the region shown by the diagonal line in FIG. 3) between the first region Rd1 and the third region Rd3. By repeatedly executing the flow from S12 to S17 in this way, the detection accuracy of the temporary touch position can be improved. The flow from S12 to S15 is performed, for example, by changing the combination of electrodes constituting the pair electrode every 5 ms period. Therefore, the arithmetic unit 8 can generally detect the temporary touch position for hundreds of 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.

Then, when the change of the combination of the pair electrodes E reaches a predetermined 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 confirmed (step S18), and the touch position TP detection process is terminated.

After the touch position detection process is completed, the process returns to FIG. 8, and when the touch position TP detection operation of the position detection device 3 is completed, the arithmetic unit 8 indicates the touch indicating the confirmed touch position TP to the CPU 24 of the computer device 2. Output the 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. Executes the processing related to. For example, when the selection screen is displayed in step S21, the CPU 24 causes the display screen 21a of the display 21 to display the selection result related to the touch operation (step S23).

-Touch position detection operation (3) (inside the 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)"), and here, focusing on the difference from "touch position detection operation (1)". explain.

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

Further, the calculation unit 8 determines the combination of the pair electrodes E initially set as the 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 S12, the pulse signal output from the pulse generator 61 is given to the first to fourth electrodes E1 to E4 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 electrodes E (here, the third electrode E3 and the fourth electrode E4) are given the same pulse signal. Try to give another pulse signal. By doing so, the detection position specificity is increased, and the effect of improving the sensitivity can be obtained. However, the same pulse signal may be given to the first to fourth electrodes E1 to E4.

The operation of steps S13 to S16 is the same as the “touch position detection operation (1)”. For the detection of the temporary touch position in step S15, for example, a corresponding look-up table (for example, 6 types of tables) is prepared for each combination of the pair electrodes E set as the electrode selection signal SC2, and the lookup is performed. Judgment should be based on the table.

In step S17, the combination of 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 a combination of pair electrodes E, all combinations of electrodes (6 ways) 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 description so far and the “touch position detection operation (1)”, and the detailed description thereof will be omitted here.

Then, when the change of the combination of the pair electrodes E reaches a predetermined 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 confirmed (step S18), and the touch position TP detection process is terminated. The flow after the touch position detection process is completed (see FIG. 8) is the same as that of the “touch position detection operation (1)” and the “other embodiments” described later, and detailed description thereof is omitted here. 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 an equal width in the vertical and horizontal directions with respect to the display screen 21a of the display 21. 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, it is preferable that the detection region Rd covers the entire display screen 21a in the fixed state of FIG. It becomes easy to install in such an inclusion state.

The configuration as shown in FIG. 6 has an advantage that versatility can be enhanced. For example, even laptop computers of the same size may have slightly different display screen sizes depending on the manufacturer. Therefore, as shown in FIG. 6, by setting the detection area Rd wider than the size of the display screen 21a, it is possible to absorb the difference in size between the two.

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 executed in this embodiment as well. As a result of step S0, here, it is assumed that the CPU 24 determines that the alignment process is necessary, and the following description will be given.

-Setting of reference coordinates (alignment processing)-
In step S41, the CPU 24 controls the display 21 to display the marker MK as an identifier and to display a message or the like prompting the touch of the marker MK on the message area Rm on the display 21. Under the control of the CPU 24, the marker MK and the message are displayed on the display 21 (step S42). For example, as shown in FIG. 6, 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 way, the user is urged to touch the marker MK1 (see FIG. 6) at the upper left of the screen. The display order, display mode, and the like of the marker MK are not particularly limited, and it is sufficient that 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 be blinked to prompt the user to touch. Further, it is not necessary to display the marker MK in all four corners. For example, if the marker MK is displayed on at least two corners facing each other in the diagonal direction, the alignment can be performed with sufficiently high accuracy. In FIG. 6, the markers MK1, MK2, MK3, and MK4 are used in the clockwise order from the upper left of the screen. However, when it does not refer to a specific marker, it may be simply described as marker MK.

Next, in step S43, the CPU 24 transmits display information to the calculation unit 8. The 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, the shape and size of the display screen 21a, display screen 21a in the display 21). Position), marker display information related to marker display (for example, display coordinates of marker MK in the display screen 21a, display order of marker MK, display time of marker MK, etc.).

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

In step S31, the calculation unit 8 refers to the display information received from the CPU 24, and sets the touch estimation area Rt of which part of the conductive layer 41 is touched first. For example, when the center of the detection area Rd and the center of the display screen 21a coincide with each other, a fan-shaped area centered 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). The touch estimation area Rt can be arbitrarily set, and the shape and size of the area are not particularly limited. For example, the touch estimation area Rt may be a rectangular area. As described above, by including the shape information, the display screen information, and the marker display information of the display 21 in the display information, the prediction accuracy of the touch estimation area Rt can be improved.

When the user touches, the position detection unit 4 performs a touch position TP detection operation (step S32). The specific operation in step S32 is the same as the process of step S10 in FIG. 9, and although detailed description thereof will be omitted here, the temporary touch position is calculated while changing the combination of the pair electrodes E, and step S18. In, the touch position of the indicator to the marker MK on the detection area 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 area Rt. When the detected touch position is outside the estimation area Rt (NG in step S33), the arithmetic unit 8 outputs an NG signal indicating to the CPU 24 that the touch detection to the marker MK was not normally detected (NG). Step S34). As a result, it is possible to prevent the position detection device 3 from being improperly attached, and it is possible to detect the failure of the position detection device 3.

Upon receiving the NG signal, the CPU 24 displays, for example, an error in the message area Rm and notifies the user to that effect. In addition to the error notification, another display may be performed. For example, it is conceivable to encourage retouching or to slightly shift the position of the marker. At this time, the flow on the position detection device 3 side returns to step S32. Further, even when the NG signal is not received, for example, when the signal is not 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 urged to retouch. You may.

On the other hand, when the detected touch position is within the estimation area Rt (OK in step S33), the arithmetic unit 8 outputs an OK signal to the CPU 24 indicating that the touch detection to the marker MK has been normally performed. 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 on the upper right of the screen) in the message area Rm, or makes a sound. Notify 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 or not 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 next to 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 processes of steps S32 to S37 are repeated until all the markers are displayed. Then, when the setting process of the reference coordinates is completed (YES in step S36), that is, when the display of all the marker MKs is completed, the calculation unit 8 registers the calculated reference coordinates in the database of the storage unit 82. The reference coordinates are coordinates that serve as a reference for converting the position on the detection area Rd to the 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 the OK signal of the marker (for example, the marker MK4) to be displayed last.

After the processing of the calculation unit 8 is completed, the CPU 24 deletes the display of the marker MK and the message on the display screen 21a, and displays, for example, the initial screen of the touch panel software (step S21). Further, the position detection device starts the touch position detection process in the same manner as in the “detection operation (1)” (see FIG. 9).

In step S10A, the calculation unit 8 detects the touch position TP on the detection area Rd in the same manner as in the “detection operation (1)”. When the detection of the touch position TP is completed, the calculation unit 8 performs the 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 area 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 performs necessary processing when the touch position TP is operated on the screen. To execute. For example, when the selection screen is displayed on the display 21 in step S21, the CPU 24 causes the display screen 21a of the display 21 to display the selection result (steps S22 and S23).

As described above, according to the present embodiment, the position detection device 3 is mounted and fixed to 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. As a result, 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 signal from the conductive layer 41. Therefore, even if the computer device 2 (display 21) does not have the touch panel function or has a touch panel that does not function normally, the touch panel function is added to the computer device 2 (display 21) after the fact. be able to.

Further, when the position of the display screen 21a of the display 21 and the position of the detection area Rd are not the same in the mounting and fixing state of FIG. 1C by performing the alignment process such as "setting of reference coordinates". Further, even when the relative positions of the touch panels are different for each mounting, the touch panel function can be effectively functioned.

The alignment process between the display screen 21a and the detection area Rw is not limited to the "setting of reference coordinates" shown in the above "detection operation (2)". For example, a conversion coefficient related to the conversion of the touch position is registered. You may create a conversion table and generate a touch coordinate signal based on the conversion table. Further, the detection result of the touch position of the marker MK may be transmitted to the CPU 24 as it is, and the coordinate conversion and the correction process of the touch position may be performed in the CPU 24. Further, the calculation unit 8 or the CPU 24 may execute the touch position conversion process and the correction process based on the movement locus, the movement amount, the movement speed, and the like from the existing touch position.

<Detection operation (3)>
Further, 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 so that the detection area Rd has the same size as the display screen 21a of the display 21. , It should be a little wider. In this case, the position detection coordinates of each position detection device 3 may be set according to the arrangement location of the plurality of position detection devices 3 (plural position detection units 4). The specific position detection operation is the same as the above-mentioned "detection operation (1)" or "detection operation (2)", and detailed description thereof will be 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 will be omitted here.

<Other embodiments>
In the above embodiment, a method of dividing the detection area with the perpendicular bisector of the line segment connecting the pair electrodes E as a boundary and detecting the touch position based on the overlapping area has been described, but other algorithms have been described. You may detect the touch position with. For example, the touch panel is divided into a plurality of detection areas, and a look-up table (not shown) that lists the standard difference information showing the standard difference information when each divided area is touched is prepared and the look is obtained. The touch position may be determined based on the uptable.

By using such standard difference information, it becomes possible to improve the detection accuracy of the touch position. Specifically, it is possible to increase the number of divided areas of the detection area to realize high definition.

Further, the detection accuracy can be improved by correcting the look-up table or using a plurality of look-up tables. Specifically, since the touch capacity varies from person to person, the look-up table prepared in advance is not always suitable. Therefore, it is possible to improve the touch position detection accuracy by correcting the look-up table or referring to the optimum table from a plurality of look-up tables.

Further, the detection accuracy of the touch position TP may be improved by performing a majority decision process from 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 is rectangular and N electrodes (N is an arbitrarily set integer) are provided on each side, the number of combinations of electrodes PN is expressed by the following equation (P). As shown in 4).

PN = 4N × 3N / 2 (4)

In the above equation (4), since the combination of the pair electrodes E on the same side has low sensitivity, it is excluded from the target of the majority voting process. That is, in the above equation (4), the combination of all electrodes when one of the pair electrodes E is arbitrarily selected and the other electrode is selected from a side different from that of one electrode is subject to majority voting. The case is illustrated, and when N = 3, the number of combinations is 54. In the majority voting process, for example, the temporary touch position may be detected for each of the 54 combinations of electrodes, and the position having the highest degree of overlap may be specified as the touch position from the temporary touch positions. Further, for example, simultaneous touches at a plurality of locations are detected by arranging the positions extracted as temporary touch positions in descending order of the degree of overlap and determining whether or not each of the multiple layers exceeds a predetermined threshold value. It is also possible to do.

Further, in the correction of the look-up table, when the marker position in the above-mentioned "setting of reference coordinates" process is touched, the look-up 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 causes the user to touch the marker MK, so that the correction can be performed based on the position of the marker MK. As a result, the look-up table can be corrected in addition to the "setting of reference coordinates", and the detection accuracy of the touch panel can be improved while reducing the user's trouble.

Further, the technique according to the present disclosure can also cope with the detection of so-called hovering. The touch capacitance is inversely proportional to the square of the vertical distance between the indicator (eg, a finger or stylus pen) and the position detector 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 hovering can be performed by combining with the touch position TP detection method described so far. Detection becomes possible. In the hovering detection, if 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 detection magnification is increased to increase the sensitivity. The touch position may be detected with. More specifically, sampling may be repeated so that the calculation unit 8 increases the detection magnification when the peak value does not increase. After that, when the peak value rises, the arithmetic unit 8 may dynamically change the detection accuracy so as to return to the original detection accuracy. Further, by determining the number of repeated samplings, the judgment can be made more reliable.

Further, it is described that the display 21 does not have the touch panel function in the above embodiment, and the touch panel function can be added ex post facto by applying the position detection system according to the above embodiment to such a display. did. The position detection system according to the present disclosure can be applied not only to such a form but also to a display originally having a touch panel function. For example, when the panel of the display having the touch panel function or the position detection function cannot be used due to a failure or damage, the position detection system 1 of the present invention can supplement the touch panel function.

Further, the electrode selection signal SC1 is assumed to be a signal indicating two or four electrodes in a pair, but the present invention 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 that of the present 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.

Further, in the above embodiment, an example is shown in which the pair electrode E to be measured is selected from the electrodes E to which the measurement signal (pulse signal) is given, but the pair electrode E gives the measurement signal. It does not have to be included in E. For example, the signal supply electrode for giving a measurement signal and the signal reception electrode for receiving the measurement signal are separated, the corresponding signal supply electrode and the signal reception electrode are paired, and the counter electrodes are arranged close to each other. Alternatively, they may be arranged so as to be slightly separated from each other, and the same effect as that of the above embodiment can be obtained.

Further, in the above embodiment, the signal source 6 gives a measurement signal to the conductive layer 41 via the electrode E connected to the conductive layer 41, but the signal source 6 is not limited to this. For example, the signal source 6 may directly or indirectly give a measurement signal to the conductive layer 41 from a place different from the electrode E.

Specifically, for example, the signal source 6 may directly give a measurement signal to the conductive layer 41 from one or a plurality of nodes (contacts) 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 having a capacitive component, a component, or the like. For example, a wiring area for signal input or a sheet-shaped signal input area is arranged facing the conductive layer 41 at a predetermined interval in the thickness direction thereof, and the signal source 6 is the wiring area or the signal. The measurement signal may be indirectly given to the conductive layer 41 via the input region. At this time, it is preferable to interpose an insulator such as air or a substrate 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 the touch panel function can be added to the image display device after the fact.

1 Position detection system 3 Position detection device 4 Position detection unit 6 Signal source 8 Calculation unit (detection side calculation unit)
21 Display (image display device)
21a Display screen 23 Communication unit (display side communication unit)
24 CPU (display side arithmetic 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 equipped with a display screen and
It is provided with 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 is
It has a display-side communication unit configured to enable communication with the position detection device, and has a display-side communication unit.
The position detection device is
A conductive layer arranged so as to face the display screen and for detecting the position of the indicator that touches the display screen,
A plurality of electrodes arranged apart from each other and each connected to the conductive layer,
A signal source that gives a measurement signal to the conductive layer,
A detection side calculation unit that calculates the position of the indicator touching the display screen based on the difference information of the output signals output from the pair of electrodes selected from the plurality of electrodes.
A position detection system including a detection side communication unit that 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. The position detection system according to claim 1, wherein the signal source gives a measurement signal to the conductive layer via an electrode selected from the plurality of electrodes. The number of electrodes to which the measurement signal is given is two or four.
The position detection system according to claim 2, wherein the detection-side arithmetic unit selects the pair of electrodes from the electrodes to which the measurement signal is given. The position detection device has a table in which standard difference information corresponding to the position of the indicator is registered for each combination of electrodes paired among the plurality of electrodes.
The detection side calculation unit is characterized in that it calculates the position of the indicator touching the display screen based on the result of comparing the difference information of the output signal with the standard difference information of the table. Or the position detection system according to 2. The image display device has a display-side calculation 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 the first touch when the position of the identifier on the display screen is touched, the detection side calculation unit corrects the standard difference information in the table based on the difference information of the output signal related to the first touch. And set the 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 the position information of the indicator on the position detection coordinates to the display side communication unit. The image display device provided with the display screen and the image display device are detachably attached and fixed to the back side of the image display device, and are arranged facing the back surface of the display screen to detect the position of the indicator touching the display screen. It is a position detection method of a position detection system including a position detection device having a detection area made of a conductive layer for the purpose.
A reference transmission step of displaying an identifier on the display screen by the image display device and transmitting the position information of the identifier to the position detection device.
The position detection device detects the first touch when the position of the identifier on the display screen is touched, and the position detection coordinates are obtained based on the first touch position related to the first touch and the position information of the identifier. Coordinate setting steps to set and
After setting the coordinates, the position detection device detects the second touch when the display screen is touched, and the second touch position related to the second touch on the position detection coordinates set in the coordinate setting step is detected. A position detection method including a touch position detection step for outputting to the image display device. The display screen has a rectangular shape and has a rectangular shape.
6. The reference transmission step, wherein the image display device displays the identifier in at least two diagonally opposed corners of the four corners of the display screen. The described position detection method. The position detection method according to claim 6 or 7, wherein in the reference transmission step, the size information of the display screen is transmitted to the position detection device by the image display device. In the coordinate setting step, the position detection device sets a touch prediction area having a predetermined size in the detection area based on the size information of the display screen and the position information of the identifier, and the first. When it is detected that the touch is inside the touch prediction area, the position detection coordinates are set, while when it is detected that the first touch is outside the touch prediction area, the position detection coordinates are set. The position detection method according to claim 8, wherein the image display device is notified to that effect without setting. In the coordinate setting step, when 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 to that effect. The position detection method according to any one of claims 6 to 9, wherein the notification is given. It is a position detection device that is detachably attached and fixed to the back surface of an image display device provided with a display screen on the front surface and for detecting the position of an indicator that touches the display screen.
A conductive layer for detecting the position of the indicator touched on the display screen, and
A plurality of electrodes arranged apart from each other and each connected to the conductive layer,
A signal source that gives a measurement signal to the conductive layer,
A calculation unit that calculates the position of the indicator touching the display screen based on the difference information of the output signals output from the pair of electrodes selected from the plurality of electrodes.
A position detection unit including a communication unit that outputs the position information of the indicator calculated by the calculation unit, and a position detection unit.
It is provided integrally with the position detection unit, and is provided with a mounting mechanism for detachably attaching the position detection unit to the image display device so that the conductive layer is arranged along the back surface of the display screen. A position detection device characterized by. The position detection device according to claim 11, wherein the signal source gives a measurement signal to the conductive layer via an electrode selected from the plurality of electrodes.

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