JP2005242452A - Coordinate inputting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coordinate input device equipped with a function for stably and efficiently notifying a main body side of the state of a pointer, and configured to realize the function without installing any battery at the pointer side. <P>SOLUTION: This coordinate inputting device for coordinate-inputting the arbitrary positions of an input region with a predetermined pointer is provided with a function for stably and efficiently notifying the main body side of the state of the pointer (pen-up/down information and switch information when the pointer is used as an electronic pen and right button/left button signal and personal identification information or the like when the pointer is used as a mouse for virtual computer), and configured to realize the function without installing any battery at the pointer side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coordinate input device, and more specifically, coordinates used to control a connected computer or write characters, figures, etc. by inputting coordinates by pointing to an input surface with an indicator or a finger. The present invention relates to a technology for improving the performance of an input device.

  Conventionally, as this type of device, various types of touch panels have been proposed or commercialized, and it is widely used because the operation of a PC or the like can be easily performed on a screen without using a special instrument. ing.

  There are various methods such as those using a resistance film and those using an ultrasonic wave, but as shown in Patent Document 1 and the like as using light, recursion outside the coordinate input surface. In a configuration in which a reflective sheet is provided, the light from the means for illuminating light is reflected by the retroreflective sheet, and the light quantity distribution is detected by the light receiving means, the angle of the area shielded by a finger or the like in the input area is detected. It is known to determine the shielding position, that is, the coordinates of the input position.

In addition, as disclosed in Patent Document 2, Patent Document 3, and the like, devices that detect the coordinates of a portion where the retroreflective member is configured around the input region and the retroreflected light is shielded are disclosed. For example, in Patent Document 1, the angle of the light shielding part is detected by detecting the peak of the light shielding part by waveform processing such as differentiation, and in Patent Document 2, one of the light shielding parts is detected by comparison with a specific level pattern. The structure which detects the edge of this and the other edge and detects the center of those coordinates is shown.

  Further, in the above-described Patent Document 1, when each pixel of the RAM imager is read out and compared by a comparator, a light-shielding portion is detected, and when there is a light-shielding portion having a certain width or more, the center of the pixels at both ends thereof is detected. A detection method for detecting (1/2 position) is shown.

U.S. Pat. No. 4,507,557 JP 2000-0105671 A Japanese Patent Laid-Open No. 2001-1472642

  By the way, in general, in order to make use of the simplicity of touch panels, there are many that are assumed to be pointed and used with fingers or pen-shaped light shielding members without electronic functions. The function of notifying the switch and the function of notifying the switch information of the pointing tool is necessary. However, at present, the function of the touch panel is such that the light shielding state changes when the pointing tool is brought into contact with the input surface. In this case, the functional performance is insufficient when used as a digitizer.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to provide a function of stably and efficiently informing the main body of the state of the pointing device, and to provide a battery on the side of the pointing device. It is an object of the present invention to provide a coordinate input device that can be realized without holding.

  To achieve the above object, according to the present invention, in an apparatus for inputting coordinates at an arbitrary position of an input area with a predetermined pointing tool, the state of the pointing tool (pen up / down information when used as an electronic pen, switch information virtual (Left button / right button signal, individual identification signal, etc.) when used as a computer mouse, etc.) is provided with a function for stably and efficiently informing the main body, and the function is realized without having a battery on the indicator side. Is.

  In the present invention, an electromagnetic wave or an electromagnetic field is sent from the main body side to the pointing device, and based on this, the state of the pointing device (electronic Pen up / down information when used as a pen, left button / right button signal when used as a mouse for switch information virtual computer, individual identification signal, etc.) are transmitted to the main body side by electromagnetic waves or electromagnetic fields.

  In particular, in the present invention, it is assumed that the input area such as a touch panel for a large projector is relatively large. In this case, the strength of the electromagnetic wave or electromagnetic field for charging can be sufficiently obtained on the indicator side. For this reason, it is conceivable that the charging time must be lengthened, and as a result, the transmission cycle from the pointing device must be lengthened, that is, the sampling frequency must be reduced. It also proposes a solution.

  According to the present invention, in the coordinate input device including the pointing tool, the input area, and the main body portion, the input area is provided with two or more light emitting portions and two or more light receiving portions around the input region, and the light emitted from a plurality of light emitting portions. Conventionally, the state of the indicator has been changed as in the case of a coordinate input device in which light passing through the vicinity of the input region is substantially parallel to the input region is shielded by the indicator and the coordinate position of the indicator is detected by the shielded position. In a coordinate input device that did not have a function for sending to the main body side transmission / reception unit, the coordinate input device has a particularly large screen when the pointing device is provided with a transponder group having a predetermined configuration and the main body side transmission / reception unit has a function corresponding thereto. Accordingly, when the input area is large, the state of the pointing tool can be transmitted from the pointing tool to the main body without using the battery and without reducing the sampling frequency.

  Specifically, the pointing device includes N transponders (N is an integer of 2 or more), each of the transponder groups includes a tuning circuit set to a different frequency, and the same frequency from the main body received by the tuning circuit. The control signal is detected from the signal of the same frequency received from the main body received by the tuning circuit, and the state of the pointing device is triggered by a predetermined control signal or one end of the signal from the main body as a trigger. The response signal is generated and transmitted to the main body by the tuning circuit. The main body transmits electromagnetic waves or electromagnetic fields having the same frequency as the tuning frequency of the transponder in the indicator in order at a certain timing. Then, a response signal sent in turn from the N transponders is combined to generate a combined response signal, and a signal indicating the state of the indicator is detected from the combined response signal. The Rukoto in batteryless, besides without reducing the sampling frequency, it is possible to transmit the state of the pointing tool from the instruction device to the main body side.

<Outline of the present invention>
The present invention introduces a method used for data exchange between a battery-less transponder and a reader used in a so-called RFID system or the like into a coordinate input device.

  The pointing device in the present invention corresponds to a transponder in the RFID, and a main body (specifically, a main body side transmitting / receiving unit) corresponds to the reader.

  In particular, in the present invention, in the exchange of the data, the means for incorporating the state determination of the pointing tool, such as a digitizer for a large screen, when the communication distance between the main body side transmission / reception unit and the pointing tool is large, it is sufficient without dropping the sampling frequency. It proposes a means to maintain a stable charge.

  In general, there are mainly two methods for charging or exchanging data from a reader to a transponder.

1) Sequential system 2) Full-duplex communication system The schematic configuration of the transponders 1) and 2) is shown in FIGS. 16 (a) and 16 (b), respectively.

  In the case of 1), the transmission or charging from the reader and the response from the transponder are alternately performed. As shown in FIG. 17, first, the reader and the transponder are supplied with electromagnetic waves or electromagnetic fields for charging and transmission from the reader to the transponder. After the elapse of a predetermined time in consideration of the distance, the charge transmission is completed. Next, the transponder transmits (responses) the charged charge toward the reader. After a predetermined response, the transponder discharges the remaining charge and repeats the same sequence again.

  In the case of 2), transmission charging is always performed from the reader side to the transponder. The transponder side performs frequency modulation on the signal from the reader side by controlling the load (resistive load) connected in parallel to the tuning circuit at a predetermined frequency while receiving the signal from the reader, and as if reflected. Reply to the leader.

  At this time, if the frequency of the signal from the reader is Fh1, and the frequency of the modulation signal on the transponder side is Fh2, the frequency of the response signal received by the reader side is Fh1 ± Fh2.

  In the case of 1), when the distance between the transponder and the reader is long or electromagnetic coupling is weak, sufficient charging can be performed by maintaining the charging time to maintain communication. On the other hand, in the case of 2), since it is always charged, there is no other way but to strengthen the electromagnetic wave or electromagnetic field transmitted from the reader. However, since there is a restriction by the Radio Law here, an electromagnetic field without a transmission electromagnetic wave cannot be strengthened unnecessarily, and as a result, there is a limit to use in a long distance or weak electromagnetic coupling.

  The present invention proposes a means for extending the charging time and not lowering the sampling frequency by using the method 1) described here.

  The pointing device of the present invention includes the transponder as means for communicating the state of the pointing device to the main body. In addition, as a means for notifying the pen-up / down, switching of the transponder response function established / not established is used.

  Specifically, as shown in FIGS. 18A to 18C, the pen up / down switching is performed when the tuning function is established or not established in the loop of the antenna or the tuning circuit of the transponder. When the tuning function is established, the main body side transmission / reception unit recognizes that there is an approximate transponder. When the tuning function is not established, the main body side transmission / reception unit recognizes that there is no transponder. Determine pen up and down.

  In this way, apart from the fact that the pointing tool does not actually exist, it can be said that pen-up / down is determined based on the fact that it cannot be seen as a transponder from the main body side transmitting / receiving unit.

Switching between establishment and non-establishment of the tuning function is, for example,
1) Cut the tuning loop itself as shown in FIG. 18 (a) 2) Shift the tuning frequency as shown in FIG. 18 (b) 3) Increase the loss of the tuning loop as shown in FIG. 18 (c), etc. There is a way.

<Sequential operation of N transponders>
The present invention is also intended for a coordinate input device in a relatively large image display device.

  In such a case, the distance between the main body side transmission / reception unit and the pointing device (transponder) is longer than that of a normal tablet or a non-contact card ID discrimination device, and the distance may be 1 m to 2 m. In this case, in order to fully charge the transponder on the pointing tool from the main body transmission / reception unit, the charging time must be set long. However, the present invention is a coordinate input device, which requires, for example, a sampling rate of several tens of points per second, and cannot increase the sequence, that is, simply increase the charging time.

  Therefore, in the present invention, a configuration is provided in which a plurality of (N) transponders are provided in the pointing tool, and these are controlled so as to operate in order at equal time intervals from the main body side transmitting / receiving unit. In this way, the individual charging time is lengthened without lengthening the sequence.

  An actual case where N = 3 will be described as an example. This is shown in FIGS. 19 (a) and 19 (b).

  On the indicator side, transponders that are tuned to the tuning frequencies F1, F2, and F3 are provided. The main body side transmission / reception unit transmits the signals of the frequencies F1, F2, and F3 to the transponder with a shift of 1/3 period. As a result, the three transponders on the pointing device operate in order, and a sampling frequency substantially three times higher can be realized.

  Conversely, if the entire sequence is extended three times, the charging time can be tripled while maintaining the sampling frequency. This situation is shown in the timing chart of FIG.

  As shown in FIG. 23, by transmitting F1, F2, and F3 with a shift of 1/3 period from the main body side transmission / reception unit, the response signal returned from the pointing device to the main body side transmission / reception unit is the original single case. The period T0 is (1/3) T0.

<Improved sequential operation of N transponders>
Next, the improvement of the sequential operation of N transponders will be described.

  As shown in FIG. 23, when the signal [F1] is transmitted from the main body side transmission / reception unit, the response signal (Resp_1A) from the pointing tool is transmitted at a period of T0 during the period when SW_A is (H). Similarly, the response signal (Resp_2A) from the pointing tool is sent in a period of T0 during the period when SW_A is (H) with respect to the signal [F2] from the main body side transmission / reception unit. In response to [F3], the response signal (Resp_3A) from the pointing tool is sent in the period of T0 during the period when SW_A is (H).

Here, since [F1], [F2], and [F3] are transmitted with a shift of 1/3 period, the above Resp_1A, Resp_2A, and Resp_3A are shifted by 1/3 period, and as a result, these sum signals ( Rsep_A ＝ Resp_1A + Resp_2A + Resp_3A
) Is a period of (1/3) T0, and the determination signal [Re_SW_A] indicating the presence or absence of Rsep_A has a timing as shown in FIG.

However, [Re_SW_A] for the rise of SW1
The rising edge of FIG. 2 causes a delay of T0 or more, and the falling edge of [Re_SW_A] with respect to the falling edge of SW1 is a delay within (1/3) T0. As described above, the delay of the rise is large because when SW1 is L, none of the transponders is charged, and at least one cycle (T0) from the rise of SW1 until the first Resp_a is transmitted. This is because the charging time is required.

  On the other hand, regarding the fall, when SW1 is turned OFF, the next Resp_a is interrupted, so that the determination can be made within (1/3) T0. That is, in this method, the rise of SW_A is detected with a delay of the original period T0 or more, and the fall of SW1 is detected within (1/3) T0.

  In view of such a fact, in the present invention, as shown in FIG. 20, when SW_A is on the “H” side, a tuning circuit for one transponder a is established, and when SW_A is on the “L” side, The pair configuration is such that the tuning circuit of the transponder b is established.

  The transponder pairs a and b operate at the same tuning frequency, and there are N combinations (hereinafter referred to as N = 3), and F1, F2 and F3 for each pair from the main body side transmitting / receiving unit ( 1/3) Control is performed sequentially by shifting T0.

<Explanation regarding the combination operation of transponders a and b>
Hereinafter, the combined operation of the transponders a and b will be described.

  Here, the timing chart of FIG. 23 will be described again.

  FIG. 23 shows the operation of FIG. 19 (transponder configuration when N = 3 and not a combination of a and b pairs).

F1, F2, and F3 are signals sent from the reader side with a shift of 1/3 period. As a result, the responses Resp_1A, Resp_2A, and Resp_3A of each transponder are controlled to be shifted by (1/3) period. In the main unit side transceiver unit, the main unit side transceiver unit demodulates Resp_1A, Resp_2A, and Resp_3A, then Rsep_A = Resp_1A + Resp_2A + Resp_3A
And a signal Re_SW_A indicating whether or not the Rsep_A exists at a predetermined pitch.

  Re_SW_A corresponds to the switch signal SW_A on the indicator side that is received and restored by the main body side transmitting / receiving unit.

  As shown in FIG. 23, Re_SW_A has a relatively large delay DL_front_A on the front side (rising side) and SW_A is delayed by a relatively small delay DL_end_A on the end side (falling side).

DL_front_A = (1/3) T0 * (3 + α1) (1-1)
DL_end_A = (1/3) T0 * α2 (1-2)
(However, 0 ≦ α1 <1, 0 ≦ α2 <1)
In this way, in the case of a transponder configuration that does not have a combination of a and b pairs as shown in FIG. 19, the SW end side timing is advanced even when a plurality of units are operated sequentially, but the front side timing is not operated sequentially. The effect of increasing the sampling frequency is small.

  For the reasons described above, the present invention has a configuration as shown in FIG. 20, that is, one of the selected tuning circuits is established and the other is not established, and is tuned to the same frequency. N sets of transponder pairs, and the N sets are adjusted to the same tuning frequency, which is different for each pair, and match each tuning frequency for the N sets of transponders from the main body side transmitting / receiving unit. In this configuration, the N transponders are operated in order by sending the signals to be transmitted in order, and all the switches provided in the N transponders operate in conjunction with each other.

  Here, the configuration of FIG. 20 is a SW that cuts the tuning loop itself, but switching such as shifting the tuning frequency as shown in FIG. 18B or increasing the loss of the tuning loop as shown in FIG. 18C. Can be constituted by “a pair of transponders in such a relationship that one of the selected tuning circuits is established and the other is not established”.

  Next, the operation of the transponder configuration shown in FIG. 20 will be described using the timing chart of FIG.

SW_A is a signal that becomes H when SW_A is “1” and L when it is “0”.
On the contrary
SW_B (= / SW_A) is a signal that is low when SW_A is “1” and high when “0”.
And

  The process of generating Resp_A and Re_SW_A from SW_A is the same as the timing chart of FIG. Similarly, the process of generating Resp_B and Re_SW_B from SW_B is the same as the timing chart of FIG.

In this configuration, Re_SW_AB is newly generated from Re_SW_A and Re_SW_B as shown in FIG. Re_SW_AB corresponds to a signal obtained by restoring SW_A by the main body side transmitting / receiving unit. Re_SW_AB, as shown in FIG.
This signal rises at the falling edge of, and falls at the falling edge of Re_SW_A.

  As a result, Re_SW_AB is delayed by DL_end_B from the rising edge of SW_A at the rising edge, and delayed by DL_end_A from the rising edge of SW_A at the falling edge.

Where DL_end_A and DL_end_B are
DL_end_A = (1/3) T0 * α1 (2-1)
DL_end_A = (1/3) T0 * α2 (2-2)
(However, 0 ≤ α1 <1, 0 ≤ α2 <1)
It can be said that this is a delay amount in which the effect of the N sets of sequential operations is sufficiently exhibited.

  As described above, in the present invention, the indicator is charged by storing electromagnetic waves or electromagnetic fields from the main body side transmission / reception unit to store power, and the state of the indication tool is changed to the main body side transmission / reception unit by the charged power. A transponder having a function of returning to the inside is provided in the indicator, and one of the tuning circuits selected as the configuration of the transponder is established and the other is not established, and they have the same frequency. N pairs of transponders tuned to each other, and the N sets are adjusted to different tuning frequencies, and signals corresponding to the respective tuning frequencies are sequentially transmitted from the main body side transmitting / receiving unit to the N sets of transponders. The N transponders are operated in turn, and the switches provided in the N transponders are operated in sequence. By operating all of them in conjunction with each other, the function of transmitting the switch signal on the pointing device of the coordinate input device to the main body side transmission / reception unit has a large screen, large input area, no battery, and sampling frequency. It can be realized without dropping.

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

<Embodiment 1>
FIG. 20 best represents the present invention.

  In this embodiment, the present invention is applied to a light-shielding touch panel. A schematic configuration of the coordinate input device according to the present embodiment will be described with reference to FIG.

  In FIG. 1, reference numerals 1L and 1R denote sensor units each having a coordinate detection light projecting unit and a coordinate detection light receiving unit, and are installed at a predetermined distance. The sensor units 1 </ b> L and 1 </ b> R are connected to a control / coordinate operation unit 2 that performs control / coordinate operations, receive control signals from the control / coordinate operation unit 2, and transmit detected signals to the control / coordinate operation unit 2. Reference numeral 3 denotes a reflecting means having a retroreflecting surface that reflects incident light in the direction of arrival as shown in FIG. 2, and directs light projected from the left and right sensor units in a range of approximately 90 ° toward the sensor units 1L and 1R. To retroreflect.

  The reflected light is detected one-dimensionally by the detection means of the sensor units 1L and 1R configured by a condensing optical system provided in the coordinate sensor unit and a line CCD or the like, and the light quantity distribution is controlled / calculated unit 2 Sent to.

  Reference numeral 100 is a main body side transmission / reception unit, 101 is a transmission / reception tuning circuit 1, 102 is a transmission / reception tuning circuit 2, and 103 is a transmission / reception tuning circuit 3. The unit is for time-series signal detection, and the unit charges and controls the battery-less indicator by sending electromagnetic waves or electromagnetic fields to the indicator through the transmission / reception tuning circuits 101, 102, 103. A function of receiving a response signal sent based on the charged power and restoring a switch signal on the pointing device is provided.

  Here, the response signal is pen up / down determination information when the pointing tool is used as a pen, information on a switch on the pointing tool, and the like.

  Reference numeral 5 denotes an input area, which is configured as a display screen of a display device such as a PDP, a rear projector, or an LCD panel, and can be used as an interactive input device.

  In such a configuration, when an input instruction with a finger or the like is given to the input area, the light projected from the light projecting means is blocked, and the reflected light due to retroreflection cannot be obtained. It can no longer be obtained.

  The arithmetic control means of the main unit detects the light shielding range of the input supported portion from the light quantity change of the left and right sensor units, specifies the detection point within the same range, and calculates the respective angles. The coordinate position on the input area is calculated from the calculated angle, the distance between the sensor units, and the like, and the coordinate value and the state of the pointing tool are connected to the PC connected to the display device via an interface such as USB. Information (pen up / down determination signal, mouse first and second control button signals, etc.) to be transmitted is transmitted to a PC or the like connected to the display device via an interface such as USB or RS232C.

  In this way, the PC can be operated such as drawing a line on the screen or operating an icon with a predetermined pointing tool.

  The present invention particularly relates to a method for transmitting and receiving information indicating the state of the pointing tool.

  Hereinafter, each part will be described in detail.

<Detailed explanation of sensor unit>
FIG. 3 is a configuration example of the light projecting means in the sensor unit.

  FIG. 3A is a diagram of the light projecting unit viewed from above (perpendicular to the input surface). In the figure, reference numeral 31 denotes an infrared LED that emits infrared light for coordinate detection. The emitted light is projected by a light projection lens 32 in a range of approximately 90 °. On the other hand, FIG. 3B is a view of the same configuration viewed from the side. In this direction (horizontal with respect to the input surface), in this direction, the light from the infrared LED 31 is projected as a light beam restricted in the vertical direction, Mainly, light is projected to the retroreflective means 4.

  FIG. 4 is a view of the detection means in the sensor unit as viewed from the direction perpendicular to the input surface.

  The detection means includes a one-dimensional line CCD 41, lenses 42 and 43 as a condensing optical system, a diaphragm 44 that limits the incident direction of incident light, and an infrared filter 45 that prevents the incidence of extra light such as visible light. ing.

  The light from the light projecting means is reflected by the retroreflective member, passes through the infrared filter 45 and the aperture 44, and the light in the approximately 90 ° range of the input surface is incident on the CCD detection surface by the condensing lenses 42 and 43. An image is formed on the pixel depending on the incident angle, and the light amount distribution for each angle is shown. That is, the pixel number represents angle information.

  FIG. 5 shows the configuration when the coordinate sensor unit 1 is formed by overlapping the light projecting means and the detection means when viewed from the horizontal direction with the input surface.

  The distance between the optical axes of the light projecting means and the detecting means may be set in a range that can be sufficiently detected from the angle characteristics of the retroreflective member.

<About the reflective member>
The retroreflective member 3 of FIG. 1 has a reflection characteristic with respect to an incident angle.

  As shown in FIG. 6, when the retroreflective tape is configured to be flat, the amount of reflected light obtained when the angle from the reflecting member exceeds 45 ° decreases, and changes occur when there is a shield. Will not be enough.

  The amount of reflected light is determined by the light amount distribution (illumination intensity and distance), the reflectance of the reflecting member (incident angle, the width of the reflecting member), and the imaging system illuminance (cosine fourth law). If the amount of light is insufficient, it is conceivable to increase the illumination intensity. However, if the reflection distribution is not uniform, when a strong portion of light is received, the portion may be saturated by the CCD as the light receiving means. There is a limit to increasing the illumination intensity. In other words, it is possible to increase the amount of light incident on the low light amount portion by making the reflection distribution of the reflecting member as uniform as possible.

In order to make the angle direction uniform, the member to which the retroreflective member 3 is attached has a shape in which triangular prisms are arranged as shown in FIG. 7, and the retroreflective member 3 is installed thereon. By doing so, the angle characteristics can be improved. Note that the angle of the triangular prism may be determined from the reflection characteristics of the retroreflective member, and the pitch is preferably set to be equal to or lower than the detection resolution of the CCD.
(About the indicator)
The indicator in the present invention is approximately pen-shaped as shown in FIG. There is a switch on the tip of the pen and the front part of the pen.

  In the present invention, as already described, a so-called transponder is provided in the pointing device, and has a function of transmitting a switch signal on the pointing device by electromagnetic waves or radio waves to the main body side transmission / reception unit without a battery.

  The transponder assumed in the present invention has a configuration as shown in FIG. Hereinafter, the configuration of the transponder will be described with reference to FIG.

  The transponder receives electromagnetic waves or electromagnetic fields sent from the main body side transmission / reception unit by a tuning circuit including a coil or antenna and a resonance capacitor, and charges the power for power supply by rectifying and smoothing the received signal. On the other hand, the control signal sent from the main body side transmitting / receiving unit is restored by demodulating the signal superimposed on the signal received by the tuning circuit.

  Further, when the charging reaches a predetermined level and a predetermined control signal is received from the main body side transmission / reception unit, the charging is stopped, and a response signal is oscillated toward the main body side transmission / reception unit through the tuning circuit. The content of the response signal is a switch signal on the pointing tool.

  The configuration of the transponder in the pointing device is such that one of the selected tuning circuits is established and the other is not established, and includes N pairs of transponders tuned to the same frequency, and The N sets are adjusted to different tuning frequencies, and signals corresponding to the tuning frequencies are sequentially sent from the main body side transmission / reception unit to the N sets of transponders. All the switches provided in the N transponders are operated in conjunction with each other.

With this configuration, the sampling period can be increased N times while maintaining the charging time for each transponder pair, or the charging time can be increased N times while keeping the sampling period constant. . In the present embodiment, N = 3.
(About the main unit side transceiver unit)
The main body side transmitting / receiving unit will be described with reference to FIG.

  The main body side transmission / reception unit transmission / reception unit includes a modulation circuit, a demodulation circuit, a transmission / reception circuit, an antenna, a control circuit, and a switch signal restoration circuit for each transmission signal Fi (i = 1 to N).

  The reason why the N systems of the transmission signals Fi (i = 1 to N) are provided is that the N transponders on the indicator are sequentially operated so that the sampling frequency is N times that of a single sampling frequency. . In the present embodiment, N = 3 corresponding to the number of transponder pairs on the indicator side, that is, three systems of transmission signals F1, F2, and F3. That is, it comprises a modulation circuit, a demodulation circuit, a transmission / reception circuit, an antenna, a control circuit, and a switch signal restoration circuit for each of F1, F2, and F3.

  By setting N = 3, the three transponders on the indicator are operated sequentially, and the sampling frequency is tripled compared to a single sampling frequency, or the sampling frequency is the same as a single sampling frequency. To triple the transponder charging time.

  As shown in FIG. 22, first, a control signal (oscillation timing superimposed signal) for transmitting F1, F2, and F3 is sent from the control circuit of the main body side transmission / reception unit to the modulation circuits 1, 2, and 3. Further, transmission signals are sent from the modulation circuits 1, 2 and 3 to the respective transmission / reception circuits F1, F2 and F3, and transmitted as electromagnetic waves or electromagnetic fields toward the pointing device. Each transmission / reception circuit is tuned to F1, F2, and F3, respectively.

  Further, as shown in [F1], [F2], and [F3] in FIG. 23, each transmission signal is transmitted with the timing shifted by 1/3 period, that is, (1/3) T0. All of these timings are based on commands from the control circuit.

Next, when each transmission circuit finishes transmitting the transmission signal, it immediately enters the reception state. This is because the end of each transmission signal becomes a response start command for each transponder.
In this way, for example, immediately after transmitting the [F1] signal, the F1 transmission / reception circuit receives Resp_1A Resp_1B sent from the transponders 1a and 1b in the pointing device, and sends it to the demodulation circuit 1, whereby Resp_1A and Resp_1B. To restore. These series of operations are the same for F1, F2, and F3, and the timing is only shifted by (1/3) T0.

The switch signal restoration circuit is the Resp_1A obtained in this way.
, Resp_1B, Resp_2A, Resp_2B, Resp_2A, Resp_2B, a switch signal, that is, a signal Re_SW_AB signal obtained by restoring SW_A, is generated and sent to the control circuit as an indicator switch signal, and further sent from the control circuit to the main unit, that is, the coordinate input device.
(Signal processing procedure for switch signals)
A signal processing procedure in the switch signal restoration circuit will be described.

  The switch signal restoration circuit uses a pen up / down signal (Pen_Down), a proxy from the Resp_1A, Resp_2A, Resp_3A, Resp_1B, Resp_2B, and Resp_3B signals sent from the pointing tool and the non-shielded signal (Shk) obtained from the coordinate detection system. It has a function to generate a mity judgment signal (Proximity).

  The method for obtaining the signal (Re_SW_AB) obtained by restoring the switch signal (SW_A) on the indicator based on Resp_1A, Resp_2A, Resp_3A, Resp_1B, Resp_2B, and Resp_3B is as described above. FIG. Yes.

  Here, a method of generating a pen-up / down signal (Pen_Down) and a proximity determination signal (Proximity) from signals Re_SW_A and Re_SW_B in the middle of the signal, and a signal with and without shading (Shk) will be described (FIG. 21'a) and (b). )reference).

  This embodiment is a light-shielding touch panel. Therefore, it is an effective way to determine the state of the pointing tool by adding information on whether or not there is a light shielding in addition to the detection of pen up / down which is one of the subjects of the present invention.

  As shown in FIG. 21 (a), the state of the pointing device is divided into four states.

  State 1 is a state in which there is no electromagnetic signal response from the pointing tool and there is no light shielding, state 2 is a state in which there is no electromagnetic signal response from the pointing tool, and there is no light shielding, and state 3 is a state in which there is no electromagnetic signal response from the pointing tool. Yes, there is light shielding, pen-up state, state 4 is a response of an electromagnetic signal from the pointing tool, and there is light-shielding and pen-down state. Here, the state 3 is a so-called proximity state.

  Further, since the range in which the electromagnetic signal spreads is considered to be wider than the vertical height of the light shielding effective region with respect to the screen, it can be determined that there is no state where there is no response to the electromagnetic signal and only the light shielding signal exists.

Re_SW_A and Re_SW_B are signals as shown in the state explanatory diagram, but as shown in FIG.
DL_front_A = (1/3) T0 * (3 + α1)
Falling
DL_end_A = (1/3) T0 * α2
Just late,
As described above, the latter is a sufficiently small amount of delay compared to the former. Therefore, it is preferable to always use one of the falling edges as the state transition information.

  Here, transitions 1, 4 and 6 in the state explanatory diagram (FIG. 21A) are DL_end_A delays and 2, 3 and 5 DL_front_A delays. In the present invention, only 1 and 4 are used as the transition timing in the sense that the logic fall (end side) is used. Further, the transition between the state 1 and the state 2 is masked by Shk = “L” with or without light shielding, and it is determined that there is no pen regardless of which transition is made. The states obtained as a result of these are shown in the bottom row of FIG. FIG. 21B shows the state explanatory diagram shown in FIG. 21A as a truth table.

  In this way, the switch on the pointing device can be detected by the main body side transmission / reception unit at a cycle of 1 / N, and further 1 / N by judging together with the light shielding presence / absence signal. It is possible to detect the status signal (Pen_Down signal, Proximity signal) of the pointing tool with a period of.

<Description of control / coordinate operation unit>
A CCD control signal, a CCD clock signal, a CCD output signal, and a coordinate detection LED drive signal are exchanged between the control / arithmetic unit and the sensor units 1L and 1R in FIG.

  FIG. 7 is a block diagram of the control / arithmetic unit and the main body side transmitting / receiving unit.

  The CCD control signal is output from an arithmetic control circuit 83 constituted by a one-chip microcomputer or the like, and performs CCD shutter timing, data output control, and the like. The clock for the CCD is sent from the clock generation circuit 87 to the sensor unit, and is also input to the arithmetic control circuit 83 for performing various controls in synchronization with the CCD.

  The coordinate detection LED drive signal is supplied from the calculation control circuit 83 to the coordinate detection infrared LED of the sensor unit via the coordinate detection LED drive circuits 84L and 84R. Detection signals from the CCD, which is the detection means of the sensor unit, are input to the A / D converters 81L and 81R of the control / arithmetic unit, and are converted into digital values under the control of the arithmetic control circuit. The converted digital value is stored in the memory 82 and used for angle calculation. A coordinate value is obtained from the calculated angle and output to an external PC or the like via the serial interface 88 or the like.

  On the other hand, a control signal to be transmitted to the pointing device from the arithmetic control circuit 83 to the main body side transmission / reception unit, a signal indicating the presence / absence of light shielding at that time, and the like are transmitted. (Pen-up / down signal, switch signal) and the like are transmitted, and these signals are output to the external PC or the like through the serial interface 88 or the like together with the coordinate calculation result.

<Explanation of light intensity distribution detection>
FIG. 14 is an overall timing chart.

  The coordinate main body side starts a coordinate detection system timing sequence after a predetermined time when F1 (or F2, F3) is transmitted. This is the timing indicated by the broken line in FIG. 14, and the coordinate detection system operates in a predetermined timing sequence from here.

  On the other hand, after the timing of starting the timing sequence of the coordinate detection system, the pointing tool state detection system detects the pointing tool state (detection of pointer switch information and pen up / down signal) independently of the coordinate detection system. The time series data processing 1 in FIG. 14 is performed. The timing sequence of the coordinate system starts with a predetermined time when F1 (or F2, F3) is transmitted.

First, both the CCD and LR are cleared. This is for erasing charges that may have jumped into the CCD due to the infrared of the time-series information signal. Next, the CCD_L is exposed, and the coordinate detection LED_L is lit during this period. Continue to CCD_R as well
The coordinate detection LED_R is turned on during this period. Thereafter, the internal charge of the CCD is transferred simultaneously with the LR, and is read into the CPU via the A / D converter. If coordinate calculation and communication with the external PC are performed based on this data, the sampling of one coordinate and time-series information signal is completed. In the present embodiment, as shown in FIG. 14, this one sampling period is approximately 10 ms. Therefore, about 100 points can be sampled per second. This speed is sufficient for a normal coordinate input device (this period is established by setting N = 3).

  Next, a procedure for calculating coordinates based on a signal data string read from the CCD will be described.

  When the signals read from the left and right CCDs are not input due to light shielding, a light quantity distribution as shown in FIG. 10 is obtained as an output from each sensor. Of course, such a distribution is not necessarily obtained in any system, but depending on the characteristics of the retroreflective sheet, the characteristics of the LED, the reflection of the image display screen surface, the deformation of the reflection surface, the time change (dirt of the reflection surface, etc.) Distribution changes.

  In the figure, the A level is the maximum light amount, and the B level is the lowest level. That is, in a state where there is no reflected light, the level obtained is near B, and the direction from B to A increases as the amount of reflected light increases. The data output from the CCD in this manner is sequentially AD converted and taken into the CPU as digital data.

  FIG. 9 shows an example of output when input is performed with a finger or the like, that is, when reflected light is blocked. Since the reflected light is blocked by a finger or the like in the portion C, the amount of light is reduced only in that portion. The detection is performed by obtaining the light shielding position from the change in the light amount distribution.

  Specifically, an initial state without input (no light shielding) as shown in FIG. 10 is stored in advance, and whether or not there is a change as shown in FIG. 9 in each sample period is different from the initial state. Only when it is determined that there has been a change, an operation for determining the input angle using that portion as an input point is performed.

  Hereinafter, data of one sensor unit will be described, but the same processing is performed on the other.

  For the sake of explanation, the following is defined by taking a sensor on one side as an example.

  The number of effective pixels of the line sensor is Nc, and the physical quantity distributed with the pixel number is expressed as a matrix of elements i (i = 1 to Nc) as follows.

Blind_data [i]: Light intensity distribution obtained by the line sensor when the light projecting means does not illuminate
Ref_data_abs [i]: Light intensity distribution obtained by the line sensor when the light projecting means illuminates and there is no light blocking (no input by an indicator or finger)
CCD_data_abs [i]: Light intensity distribution obtained by the line sensor when the light projecting means illuminates and there is light shielding (with an indicator or finger input). Also, from Ref_data_abs [i], CCD_data_abs [i] to Blind_data Subtract [i]
Ref_data [i] = Ref_data_abs [i] −Blind_data [i] Equation 1-1
CCD_data [i] = CCD_data_abs [i] −Blind_data [i] Equation 1-2
Also, the ratio of CCD_data [i] to Ref_data [i]
Norm_dat [i] = CCD_data [i] / Ref_data [i] Equation 1-3
Vth_sh: threshold value for determining whether there is light shielding Equation 1-4
Vth_posi: Threshold value for shading position calculation Formula 1-5
It is defined as

  When the power is turned on, the CCD output is first AD-converted without illumination from the light projecting means without input, and this is stored in the memory as Bas_data [i]. This is data for evaluating variations in sensitivity of the CCD and the like, and is data near the level B (broken line) in FIG. Here, N is a pixel number, and a pixel number corresponding to an effective input range is used.

  Next, the light quantity distribution in the state illuminated from the light projecting means is stored. This data is represented by a solid line in FIG. 8 and is Ref_data_abs [Nc].

Here, in order to correct the sensitivity variation and variation of the CCD,
Ref_data [i] = Ref_data_abs [i] −Blind_data [i] Expression 2-1
Calculate

  This completes the basic initialization and starts the normal sampling loop. In normal sampling, first, CCD_data_abs [Nc] is measured.

Next, in order to correct the sensitivity variation and variation of the CCD,
CCD_data [i] = CCD_data_abs [i] − Blind_data [i]... Formula 2-2
Perform the calculation.

Next, as a physical quantity that expresses a purely shaded state,
Norm_data [i] = CCD_data [i] / Ref_data [i] Equation 2-3
Calculate

  Hereinafter, based on this Norm_data [i], the calculation of the light shielding depth, the presence or absence of light shielding is determined from the light shielding depth, and if there is light shielding, the light shielding position is calculated (signal to be sent to the main body side transmitting / receiving unit) And Shk = “1”). Further, XY coordinates are calculated from the light shielding position obtained for each of the two line sensors.

  Here, in determining the presence or absence of light shielding from the light shielding depth, a predetermined threshold value Vth_sh (between 0 and 1, usually about 0.2 to 0.3) is set for Norm_data [i]. When the number of pixels exceeding the threshold value Vth_sh is a predetermined number or more, it is determined that there is light shielding, that is, there is an input.

  In addition, as described above, by subtracting the intensity distribution without illumination from the absolute intensity distribution, it is possible to avoid the influence of the CCD sensitivity unevenness, CCD variation, etc., and the intensity distribution always without light shielding. By standardizing the intensity distribution when there is light shielding with reference as the reference, the light shielding depth and light shielding position can be obtained without being affected by fluctuations in the luminance distribution on the illumination side and fluctuations in the optical system such as the reflecting member. be able to.

  Next, a method for actually calculating the light shielding position from Norm_data [i] will be described.

  The threshold value Vth_posi is applied to this data, and the angle is obtained from the pixel numbers of the rising and falling portions with the center of both as the input pixel (that is, the central pixel number Np of the data string is obtained). In order to calculate an actual coordinate value from the obtained center pixel number, it is necessary to convert it into angle information. In actual coordinate calculation described later, it is more convenient to obtain the value of the tangent at the angle rather than the angle itself.

  A table reference or a conversion formula is used for conversion from the pixel number to tan θ. Predetermined data is obtained by actual measurement, an approximate expression is created for this data, and pixel number and tan θ conversion is performed using the approximate expression. For example, when a high-order polynomial is used as the conversion formula, the accuracy can be ensured, but the order and the like may be determined in consideration of the calculation capability and the required accuracy. For example, when a fifth order polynomial is used, six coefficients are required, and this data may be stored in a nonvolatile memory or the like at the time of shipment.

Now, when the coefficients of the fifth order polynomial are L5, L4, L3, L2, L1, and L0,
tan θ is
tan θ = (L5 * Npr + L4) * Npr + L3) * Npr
L2) * Npr + L1) * Npr + L0 (7)
Can be represented.

  If the same thing is done for each sensor, the respective angle data can be determined. Of course, in the above example, tan θ is obtained, but the angle itself may be obtained and then tan θ may be obtained.

<Description of coordinate calculation method>
Coordinates are calculated from the obtained angle data.

  FIG. 11 is a diagram showing a positional relationship with the screen coordinates.

  Each sensor unit is mounted on the left and right sides of the input range, and the distance between them is represented by Ds. The center of the screen is the origin position of the screen, and P0 is the intersection of the angle 0 of each sensor unit.

  The respective angles are θL and θR, and tan θL and tan θR are calculated using the above polynomials.

At this time, the x and y coordinates of the point P are x = Ds * (tan θL + tan θR) / (1+ (tan θL * tan θR)) (8)
y = -Ds * (tan θR_tan θL_ (2 * tan θL * tan θR)) / (1+ (tan θL * tan θR)) + P0Y (9)
Calculated by

  FIG. 12 is a flowchart showing steps from data acquisition to coordinate calculation.

  When the power is turned on in S101, various initializations such as port setting of the arithmetic control circuit, timer setting, etc. are performed (S102). S103 is a preparation for removing unnecessary charges that is performed only at startup. In a photoelectric conversion element such as a CCD, unnecessary charge may be accumulated when it is not operated. If the data is used as it is as reference data, it becomes impossible to detect or causes false detection. In order to avoid this, data is first read multiple times without illumination. In S103, the number of times of reading is set. In S104, unnecessary charges are removed by reading data a predetermined number of times without illumination.

  S105 is a determination sentence for repeating a predetermined number of times. S106 is fetching of data without illumination as reference data, and corresponds to the above Bas_data. The data fetched here is stored in the memory and used for calculation thereafter.

  This and another reference data, data Ref_data corresponding to the initial light quantity distribution when illuminated, are fetched (S108), and are also stored in the memory. Up to this step is the initial setting operation when the power is turned on, and then the normal capturing operation is performed.

In S109, a control signal or charging signal F1 (or F2, F3) to the pointing tool is transmitted. A series of normal operations including detection of coordinates, detection of the state of the pointing tool, and transmission of the result to a PC or the like is performed after S109. Normally, after completing one cycle, the process proceeds to S109 again. In S110, the light amount distribution obtained by the CCD is captured, and in S111, the presence / absence of a light-shielding portion is determined based on a difference value from Ref_data. If it is determined in S112 that there is a light-shielding area, the ratio is calculated in S112 by the processing of Expression (2). With respect to the obtained ratio, a rising part and a falling part are determined by a threshold value, and the center is calculated by the equations (4), (5), and (6).

  In S113, the presence or absence of light shielding is detected from the light amount distribution. Tan θ is calculated from an approximate polynomial from the center value obtained in S114 (S115), and x and y coordinates are calculated from the tan θ values in the left and right sensor units using equations (8) and (9).

  On the other hand, at the same time as S1100 to S115, the main body side transmission / reception unit receives a response signal by an electromagnetic wave or electromagnetic field from the transponder in the pointing tool and generates a signal (PenDown, Proximity) indicating the state of the pointing tool. In S116, a signal (PenDown, Proximity) indicating the coordinate calculation result and the state of the pointing tool is transmitted to a PC or the like. In normal operation, the process thereafter returns to S109, and at the end, the process proceeds to S117 and ends.

<Embodiment 2>
This embodiment is applied to another method of a touch panel. That is, the first and second light-emitting element groups, the first light-receiving element group, the second light-emitting element group, and the second line that are linearly arranged on opposite sides of the periphery of the predetermined input region, respectively. The present invention is applied to a coordinate input device composed of a light receiving element group.

  The light shielding position in the X direction is calculated from the light intensity distribution detected by the first light receiving element group arranged in the X direction, and the light shielding position in the Y direction is calculated by the second light receiving element group arranged in the X direction. It is calculated from the detected light intensity distribution, and coordinates are calculated from the light shielding position in the X and Y directions by the control calculation means.

  Even in such a touch panel, as described above, the present embodiment also includes a so-called transponder in the pointing device, and a function of transmitting a switch signal on the pointing device by electromagnetic waves or radio waves to the main body side transmission / reception unit without a battery. have.

  The transponder assumed in the present invention has a configuration as shown in FIG.

The configuration of the transponder will be described below with reference to the figure. The transponder receives electromagnetic waves or electromagnetic fields sent from the main body side transmitting / receiving unit by a tuning circuit including a coil, an antenna and a resonance capacitor, and rectifies the received signal. The electric power for the power source is charged by smoothing.

  On the other hand, the control signal sent from the main body side transmitting / receiving unit is restored by demodulating the signal superimposed on the signal received by the tuning circuit. Further, when the charging reaches a predetermined level and a predetermined control signal is received from the main body side transmission / reception unit, the charging is stopped, and a response signal is oscillated toward the main body side transmission / reception unit through the tuning circuit. The content of the response signal is a switch signal on the pointing tool.

  The structure of the transponder on the pointing device is such that one of the selected tuning circuits is established and the other is not established, and includes N pairs of transponders that are tuned to the same frequency, and The N sets are adjusted to different tuning frequencies, and signals corresponding to the respective tuning frequencies are sequentially sent from the main body side transmission / reception unit to the N sets of transponders. All the switches provided in the N transponders are operated in conjunction with each other.

  With this configuration, the sampling period can be increased N times while maintaining the charging time for each transponder pair, or the charging time can be increased N times while keeping the sampling period constant. . In this embodiment, N = 3.

  The present invention is applicable to a coordinate input device that inputs coordinates by pointing to an input surface with an pointing tool or a finger, and is used for controlling a connected computer or writing characters, figures, etc. Useful for this.

1 is an overall view showing features of the present invention. It is a figure explaining the retroreflection of this invention. (A) is a block diagram of a 1st light emission part, (b) is a block diagram of a 1st light emission part. It is a 1st light-receiving unit block diagram. It is a 1st light-receiving unit block diagram. It is a 1st light-receiving unit light intensity distribution. It is a block diagram which shows the structure of the coordinate input device which concerns on Embodiment 1 of this invention. It is explanatory drawing of light shielding. It is explanatory drawing of light shielding. It is explanatory drawing of light shielding. It is explanatory drawing of a coordinate calculation means. It is a flowchart which shows the operation procedure of the coordinate input device which concerns on this invention. It is a figure which shows the basic shape of an indicator. It is a whole sequence diagram. It is a block diagram which shows the structure of the coordinate input device which concerns on Embodiment 2 of this invention. It is explanatory drawing of a transponder. It is transponder operation | movement explanatory drawing. It is explanatory drawing of the switch of a transponder tuning circuit. It is explanatory drawing of a transponder multiple structure. It is explanatory drawing of the transponder structure in embodiment of this invention. (A) is state explanatory drawing in an Example, (b) is a truth table in an Example. It is explanatory drawing regarding the main body side transmission / reception unit in an Example. It is explanatory drawing which operates a transponder sequentially. It is explanatory drawing of a switch signal restoration procedure.

Explanation of symbols

1L, 1R Sensor unit 2 Control / coordinate operation unit 3 Reflecting means 5 Input area 31 Infrared LED
32 lenses 41 line CCD
42, 43 Lens 44 Aperture 45 Infrared filter 82 Memory 83 Operation control circuit 88 Serial interface 100 Main body side transmission / reception unit 101 Transmission / reception tuning circuit 1
102 Transmission / reception tuning circuit 2
103 Transmission / reception tuning circuit 3

Claims (7)

A coordinate input device comprising an indicator, an input area, and a main body,
Provided with a predetermined coordinate position detection function, in addition to the coordinate detection function, the main body unit receives an electromagnetic wave or an electromagnetic field to the indicator, and receives a response signal sent as an electromagnetic wave or an electromagnetic field from the indicator The indicator has an electromagnetic wave or electromagnetic field sent from the main body and stores the power by charging it, and the state of the indicator as a response signal to the main body based on the power A coordinate input device which sends a signal representing   The indicator includes a transponder, the transponder includes a tuning circuit adjusted to the same frequency as a transmission signal from the main body, stores a signal from the main body received by the tuning circuit as power, and the main body received by the tuning circuit A control signal is detected from the signal from the control signal, a response signal indicating the state of the pointing device is generated by using a predetermined control signal or one end of the signal from the main body as a trigger, and transmitted to the main body side by the tuning circuit. The coordinate input device according to claim 1.   The indicator includes a plurality of switches, and at least one of the switches has a function of electrically switching between establishment and non-establishment of the tuning circuit of the transponder, and controls a response signal representing the state of the indicator by the switching. The coordinate input device according to claim 1.
A coordinate input device comprising an indicator, an input area, and a main body, comprising two or more light emitting units and two or more light receiving units in the periphery of the input region, wherein the vicinity of the input region emitted from the plurality of light emitting units In the coordinate input device in which light that passes substantially parallel to the input area is shielded by the indicator, and the coordinate position of the indicator is detected by the shielded position,
The indicator includes N transponders (N is an integer of 2 or more), each of the transponders includes a tuning circuit set to a different frequency, and a signal of the same frequency from the main body received by the tuning circuit is supplied as power. The control signal is detected from the signal of the same frequency from the main body received by the tuning circuit, and a response signal indicating the state of the pointing device is triggered by a predetermined end of the control signal or the signal from the main body. And has a function of transmitting to the main body side by the tuning circuit, and the main body portion sequentially transmits an electromagnetic wave or an electromagnetic field having a frequency matching the tuning frequency of the transponder in the indicator at a certain timing in order, N A response signal sequentially sent from the transponder is generated, and a signal representing the state of the pointing device is detected from the response signal. Coordinate input device.   Each of the N transponders is a switch on an indicator, and is configured so that the establishment and non-establishment of a tuning circuit can be switched at the same time. The coordinate input device according to claim 4.
A coordinate input device composed of an indicator, an input area, and a main body, comprising two or more light emitting units and two or more light receiving units in the periphery of the input region, and the vicinity of the input region region emitted from a plurality of light emitting units In the coordinate input device in which the light passing through the input area is shielded by the indicator, and the coordinate position of the indicator is detected by the shielded position.
The indicator includes a transponder group, and each of the transponder groups stores a signal of the same frequency from the main body received by the tuning circuit as electric power, and receives a control signal from the signal of the same frequency from the main body received by the tuning circuit. Detecting and generating a response signal indicating the state of the pointing tool triggered by a predetermined end of a predetermined control signal or signal from the main body, and transmitting the response signal to the main body side by the tuning circuit. A switch on the indicator so that a pair of transponders tuned to the same frequency (N is an integer greater than or equal to 2) and the tuning circuit of one of the selected transponders is established and the other is not established And the N pairs are adjusted to different tuning frequencies, and the N transponders -Pairs are configured to be switched at the same time by a switch on the pointing tool, and the main body portion sequentially transmits electromagnetic waves or electromagnetic fields having the same frequency to the N transponder pairs at equal intervals. The coordinate input device according to claim 6, wherein response signals sequentially transmitted from a plurality of transponder pairs are combined to restore switch information on the pointing tool. The coordinate input device according to claim 6 has a function of determining whether or not the light is shielded by the pointing tool. The pointing tool restored from the signal Shk (1: light-shielded, 0; no light-shielded) by the main body unit. When the upper switch information is PenDown (1: pen down)
1) Pen-down when Shk∩PenDown = 1 2) Proximity when Shk∩ (/ PenDown) = 1 3) When Shk = 0, determination is made that there is no indicator. Coordinate input device.

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