JP4128296B2 - Digitizer sensor coil scanning method - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a digitizer that detects coordinate information of a position indicator by electromagnetic action and inputs the coordinate information to a computer, and a sensor coil scanning method thereof. In particular, the present invention relates to a digitizer that performs electromagnetic interaction between a position indicator and a tablet, and a coordinate detection method thereof.
[0002]
[Prior art]
A digitizer is a device that inputs coordinate information to a computer, and includes a position indicator (called a stylus pen, a cursor, etc.) and a tablet (plate-like). A conventional technique called a transmission / reception digitizer is known for electromagnetically coupling a position indicator and a tablet.
[0003]
As shown in FIG. 2, the transmission / reception digitizer includes loop coil groups (X-axis coils X01-X40 and Y-axis coils Y51-Y80 provided on the tablet side. Here, 40 and 30 respectively are examples. 2 is omitted and 5 or 4 are drawn), and a position indicator 420 (from a coil and a capacitor) having a coil that electromagnetically interacts with the loop coil group. Resonance circuit is built-in, and electromagnetic resonance is achieved by resonating at a natural resonance frequency determined from the values of those elements, for example, 500 kilohertz), and a signal of a specific frequency (the natural resonance frequency of the position indicator) A transmitting circuit 430 for sending to the loop coil group, a receiving circuit 440 for receiving a signal output from the loop coil group, and processing the received signal to check the status of the indicator. A signal processing circuit 450. Since both the transmission circuit and the reception circuit are on the tablet side, this type of digitizer is referred to as a transmission / reception digitizer. Here, the X-axis coil refers to a coil disposed in the X-axis direction. In other words, the longitudinal direction of the coil is parallel to the Y axis. Since the output value is used to detect the X coordinate, it is called an X-axis coil. The Y-axis coil refers to a coil disposed in the Y-axis direction, in other words, a coil whose longitudinal direction is provided in parallel to the X-axis. Since the output value is used to detect the Y coordinate, it is called a Y-axis coil. These loop coils may be referred to as position detection coils or sensor coils (hereinafter simply referred to as “coils” in the present specification unless there is a particular possibility of confusion).
[0004]
The operation of a conventional transmission / reception digitizer will be briefly described. Which coil is supplied with the signal from the transmission circuit 430 (or which signal is passed from the coil to the reception circuit 440) depends on the transmission / reception changeover switch 435, the X-axis coil selection switch 406, and the Y-axis coil selection switch 416. Depends on the work of These three switches are controlled by a control circuit (not shown). A signal of 500 kHz is supplied to the coil for 32 microseconds (hereinafter referred to as “unit period”) after one of the X-axis coil and the Y-axis coil is selected. (The magnitude of 32 microseconds and 500 kilohertz is an example.) If an alternating magnetic field is generated thereby, and the position indicator 420 exists in the vicinity thereof, the resonance circuit in the position indicator 420 is excited to resonate. Begin. In the next unit period, while continuing to select the same coil on the tablet side, by switching the transmission / reception changeover switch 435, the alternating magnetic field returning from the position indicator 420 to the tablet side is received, and the signal is received by the receiving circuit. Pass to 440. Although the resonance of the resonance circuit in the position indicator 420 is attenuated but does not disappear immediately, the signal can be detected by the reception circuit 440. The magnitude (voltage level) of this signal increases as the selected coil on the tablet side is closer to the position of the position indicator 420.
[0005]
By performing this series of operations from the X-axis coils X01 to X40 and further from the Y-axis coils Y51 to Y80, it is possible to acquire the signal level distribution for each of the X-axis and Y-axis. If the coil pitch is appropriately set, signals can be acquired from three adjacent coils. The coordinates of the position indicator can be obtained by regarding the level distribution as a parabola and obtaining its vertex. By performing this calculation for each of the X axis and the Y axis, the two-dimensional coordinates of the position indicator 420 with respect to the tablet are obtained. This calculation depends on the functions of a control circuit and a signal processing circuit 450 (not shown).
[0006]
[Problems to be solved by the invention]
In the transmission / reception digitizer described above, when the digitizer is turned on, or when it is out of the range that the position indicator can detect and then reenters, the approximate position of the position indicator is located. Since it is unknown, the sensor coil needs to be scanned over the entire position detection region. The scan at this time is called an approximate position detection operation. Once the approximate position is known, only the sensor coil in the vicinity needs to be scanned, so the time required for coordinate detection can be relatively short (detailed position detection operation). However, the time required for the approximate position detection is relatively long. In particular, the wider the coordinate detection area of the digitizer (for example, A0 size), the longer it takes.
[0007]
It is known that there is room for selecting whether to select all scan or skip scan in the method of the approximate position detection operation. All-scan is literally scanning all X-axis loop coils and all Y-axis loop coils. In the above example, a total of 70 coils are scanned, 40 and 30. As an example of the skip scan, there is one jointly proposed by Masanobu Yamamoto and Takeshi Yoneda (Japanese Patent Laid-Open No. 8-286814).
[0008]
An example of skip scanning will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of the skip scanning method. FIG. 3 schematically shows the relationship between a tablet having a large number of sensor coils and a position indicator when viewed from the side. The “schematic” means that the sensor coil is represented by a single circle or double circle as if it were a straight line ignoring the actual shape (loop shape), and the position indicator is like a pencil silhouette. This means that only a contour is represented by a simple shape. The first, third, fifth and seventh (odd number) coils from the left are represented by single circles. The second, fourth and sixth (even-numbered) coils from the left are represented by double circles. Hereinafter, the first coil from the left is abbreviated as coil 1. Curved arcs centered on coil 1, coil 3, and coil 5 are drawn. These curved arcs indicate the limit that the alternating magnetic field generated from the coil 1, the coil 3, and the coil 5 excites the resonance circuit in the position indicator and detects the position indicator.
[0009]
Further, in FIG. 3, an arrow pointing from the bottom to the top represents an alternating magnetic field emanating from the coil toward the position indicator, and an arrow pointing from the top to the bottom constitutes the position indicator (more specifically, a resonance circuit in the position indicator). The alternating magnetic field is emitted from the coil) toward the sensor coil on the tablet side. Although four position indicators are displayed in FIG. 3, it does not mean that four position indicators exist on the tablet at the same time, and the position indicator is located at the position depicted in the figure. This means that the digitizer can detect this position indicator.
[0010]
Here, the concept of “reading height” is considered. “Reading height” refers to the height limit of how high the position indicator can be detected from the tablet. Usually, it is expressed as a vertical distance from the tablet plate surface. Consider performing a skip scan in which only the odd-numbered coils are used for detection in the transmission / reception digitizer described above and the even-numbered coils are skipped. Then, as can be seen from FIG. 3, the reading height is high immediately above the odd-numbered coils used for detection, and the reading height is low directly above the even-numbered coils to be skipped. As a result, a phenomenon occurs in which the reading height varies depending on the location on the tablet plate surface. Two horizontal lines drawn in broken lines in FIG. 3 represent this situation. The higher of the two horizontal lines represents the reading height near the coil used for detection, and the lower horizontal line represents the reading height near the skipped coil.
[0011]
This phenomenon can be understood as “the reading height has a fluctuation range”. The magnitude of this fluctuation range increases as the skip rate increases. If the curved arc indicating the limit of the alternating magnetic field in FIG. 3 is compared to a mountain, the pitch of adjacent mountains is increased and the valley is deepened as the skip rate increases. Here, the skip rate is a ratio of skipping the coil to be detected, and is 50% when one of the two is skipped, and 75% when skipping three of the four.
[0012]
Consider how the large fluctuation in the reading height affects the coordinate input operation by the digitizer. In the first place, as described above, skip scanning is more necessary for larger digitizers. By the way, as one of the uses of a large-sized digitizer, there is a use in which a large drawing is pasted on the plate surface and used to input coordinate information to a computer. In such an input operation, frequent input on a large board surface is frequently performed (an operator instructs a jump location using a position indicator). Therefore, it is necessary to detect the position from a state where the approximate position is unknown by losing sight of where the position indicator is.
[0013]
If a thick drawing is pasted, or if multiple sheets of paper are pasted, depending on the input location, there may be a gap between the "variation width of the reading height". . In this case, a solution may be considered in which the detection operation is performed again with the skipped coil. However, this is a solution that is far from the original purpose of skip scanning, which is to shorten the time required for the approximate position detection operation.
[0014]
The present invention has been made in view of such problems, and provides a digitizer and a sensor coil scanning method in which the “variation width of the reading height” in skip scanning is further reduced.
[0015]
[Means for solving the problems]
In order to solve the above problems and achieve the object of the present invention, a sensor coil scanning method of the present invention includes a position indicator having a resonance circuit and a transmission for transmitting a signal that can resonate the resonance circuit in the position indicator. Means, a receiving means capable of receiving a signal returned as a result of resonance from a resonance circuit in the position indicator, a signal processing means for processing the signal received by the receiving means and detecting the state of the position indicator, substantially in the same plane A plurality of sensor coils arranged in two directions (X-axis direction and Y-axis direction) perpendicular to each other, and a tablet having connection means for selectively connecting the sensor coils and the transmission means or reception means. a sensor coil scanning method of the digitizer, transmitted from one of the plural X-axis direction sensor coils, immediately after stopping the transmission, or X-axis direction of the sensor coils the transmission The process of receiving at another X-axis direction Sensakoi Le with a space therebetween distance skip a certain number of coils is repeated for some of the plurality sensor coils of the X-axis direction, the resulting received It is characterized in that coordinate information for the tablet of the position indicator is detected by processing the signal.
[0016]
Further, the sensor coil scanning method of the present invention includes a position indicator having a resonance circuit, a transmission means for transmitting a signal capable of resonating the resonance circuit in the position indicator, and a resonance result from the resonance circuit in the position indicator. Receiving means capable of receiving a return signal, signal processing means for processing the signal received by the receiving means and detecting the state of the position indicator, two directions (X-axis direction and substantially perpendicular to each other) provided in substantially the same plane Y-axis direction) to a number disposed a sensor coil, a sensor coil scanning method of the digitizer comprising a tablet having a connection means for selectively connecting said transmitting means or the receiving means and the sensor coil, a plurality of Y sending from one of the axial direction of the sensor coils, immediately after stopping the transmission, the spatial distance skip a certain number of coils from the Y-axis direction of the sensor coils the transmission The process of receiving at another Y-axis direction Sensakoi Le had repeated for some of the plurality sensor coils of the Y-axis direction, with respect to the tablet of the position indicator by processing a received signal obtained as a result It is characterized by detecting coordinate information.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is an explanatory diagram of a scanning method according to the present invention. The apparatus configuration is the same as that of the conventional apparatus shown in FIG. FIG. 1 illustrates a case where only an odd-numbered coil is used for detection at a skip rate of 50%. The odd-numbered coils refer to X01, X03, X05,..., X39 for the X-axis coil, and Y51, Y53, Y55,. Say. Now, assuming that FIG. 1 shows an X-axis coil, the single circle shown in FIG. 1 shows X01, X03, X05, and X07 from the left.
[0019]
The scanning method according to the present invention will be described below with reference to FIGS. 1 and 2 at the same time. For convenience, the skip scan in the approximate position detection of the X coordinate will be described. The approximate position detection of the Y coordinate is similarly performed.
[0020]
First, in the first unit period, the transmission / reception changeover switch 435 connects the signal from the transmission circuit to the X-axis coil selection switch 406 and the X-axis coil selection switch 406 switches the X-axis coil X01 under the control of a control unit (not shown). Select (this is hereinafter simply expressed as “transmit from X01”). At this time, an alternating magnetic field is emitted upward from X01 (three upward arrows pointing upward from the left single circle in FIG. 1). If there is a position indicator in the vicinity, the alternating magnetic field excites a resonance circuit provided in the position indicator, and the resonance circuit starts to vibrate.
[0021]
Next, in the second unit period, the transmission / reception changeover switch 435 disconnects the connection in the first unit period under the control of a control unit (not shown), the X-axis coil selection switch 406 selects the X-axis coil X03, and the X-axis coil. The signal generated at X03 is sent to the receiving circuit 440, and the output is sent to the signal processing circuit 450 (this is hereinafter simply expressed as "received at X03"). If there is a position indicator in the vicinity, the forced vibration of the resonance circuit is terminated by cutting the signal from the transmission circuit 430, and the free vibration is started. This free vibration attenuates but does not disappear immediately, so that a state in which an alternating magnetic field is generated from the coil constituting the resonance circuit is maintained for a while. A signal is generated in the X-axis coil X03 due to the influence of the alternating magnetic field. This is detected by the receiving circuit 440 and sent to the signal processing circuit 450.
[0022]
Further, transmission is performed from X03 in the third unit period, and reception is performed at X05 in the fourth unit period. In the fifth unit period, transmission is performed at X05, and in the sixth unit period, reception is performed at X07. Thereafter, the same is repeated, and transmission is performed at X37 in the 37th unit period, and reception is performed at X39 in the 38th unit period. When the reading height when such a scanning method is employed is measured, it can be seen that it has a substantially constant height as shown by the dotted line in FIG.
[0023]
Here, in order to bring about such a result, the coil arrangement and the conditions to be satisfied by the scanning method will be organized and considered. First of all, a large number of sensor coils are arranged at equal intervals, and secondly, skip scanning that skips (n-1) of n consecutive coils, and the skip rate is constant. (N is an integer such as 2, 3, 4, etc.) Third, when considering the coils used for detection in order from one end to the other end, the transmission period for transmitting with the first coil This is a scanning method that continues repeatedly, such as a reception period received by the second coil, a transmission period transmitted by the second coil, and a reception period received by the third coil.
[0024]
As described above, the skip rate is 50% when one is skipped for two lines, 67% when two are skipped for three lines, and 75% when three are skipped for four lines. Considering the coil used for detection when the skip rate is 75% as an example, X04, X08, X12, X16, X20, X24, X28, X32, X36, and X40 are used for detection and other coils are skipped. .
[0025]
【Example】
[Example 1]
Consider the special case where n is 1. When n is 1, n-1 is zero, so it can no longer be skipped. However, this is a new scanning method different from the scanning method of the conventional transmission / reception digitizer. In other words, specifically for scanning of the X-axis coil, X01 is transmitted in the first unit period, X02 is received in the second unit period, X02 is transmitted in the third unit period, X03 is received in the fourth unit period, Sent at X03 in the fifth unit period, received at X04 at the sixth unit period, transmitted at X04 at the seventh unit period, ... (omitted) ..., received at X39 at the 76th unit period, 77th unit In this scanning method, X39 is transmitted during the period and X40 is received during the 78th unit period. The same applies to the Y-axis coil. Even in the special case where n is 1, the effect that the variation in the reading height is small can be obtained similarly.
[0026]
[Example 2]
In the above-described embodiment, the X-axis coil and the Y-axis coil are arranged at equal intervals, and the skip rate is constant. In that case, the reading height can be obtained at a substantially constant height on the entire surface of the tablet plate. However, even when this equidistant property is not strictly observed, the object of the present invention can be achieved in which fluctuation in reading height is reduced. This is because the reading height can be obtained almost linearly between the coils used for detection.
[0027]
[Example 3]
In the above-described embodiment, the skip scan is performed for both the X axis and the Y axis. However, if the position indicator is detected by executing the skip scan for only one of the axes, the details are as follows. An embodiment that enters the position detection operation is also possible.
[0028]
[Example 4]
In the above-described embodiment, the scanning direction is determined and skip scanning is performed in order, but an embodiment in which scanning is selected at random without sequentially scanning is also possible. Even in such a case, if transmission is performed in a certain unit period, the coil used for the transmission and a coil (coil belonging to the same axis) that is separated by a predetermined spatial distance will be protected even in the next unit period. Then, the effect of the present invention can be obtained that the fluctuation of the reading height is reduced.
[0029]
【The invention's effect】
With the above-described configuration, the approximate position detection operation can be performed quickly. In the skip scan of the transmission / reception digitizer, the fluctuation range of the reading height can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a scanning method according to the present invention. FIG. 2 is a block diagram of a transmission / reception digitizer. FIG. 3 is an example of a skip scanning method.
X01-X40 X-axis coil Y51-Y80 Y-axis coil 406 X-axis coil selection switch 416 Y-axis coil selection switch 420 Position indicator 430 Transmission circuit 435 Transmission / reception changeover switch 440 Reception circuit 450 Signal processing circuit

Claims (5)

Position indicator having a resonance circuit, transmission means for transmitting a signal capable of resonating the resonance circuit in the position indicator, and reception means for receiving a signal returned as a result of resonance from the resonance circuit in the position indicator The signal processing means for processing the signal received by the receiving means and detecting the state of the position indicator, provided in a large number in two directions (X-axis direction and Y-axis direction) which are provided in substantially the same plane and are orthogonal to each other. A sensor coil scanning method for a digitizer comprising a sensor coil and a tablet having a connection means for selectively connecting the sensor coil and the transmission means or reception means,
Sending from one of said plurality of X-axis direction sensor coils, immediately after stopping the transmission, spaced spatial distance skip a certain number of coils from the X-axis direction of the sensor coils the transmission the process of receiving at Sensakoi Le other X-axis direction, the number is repeated for one of the X-axis direction of the plurality sensor coils, the tablet of the position indicator by processing a received signal obtained as a result A sensor coil scanning method characterized by detecting coordinate information with respect to. Position indicator having a resonance circuit, transmission means for transmitting a signal capable of resonating the resonance circuit in the position indicator, and reception means for receiving a signal returned as a result of resonance from the resonance circuit in the position indicator The signal processing means for processing the signal received by the receiving means and detecting the state of the position indicator, provided in a large number in two directions (X-axis direction and Y-axis direction) which are provided in substantially the same plane and are orthogonal to each other. A sensor coil scanning method for a digitizer comprising a sensor coil and a tablet having a connection means for selectively connecting the sensor coil and the transmission means or reception means,
Sending from one of said plurality of Y-axis direction of the sensor coils, immediately after stopping the transmission, spaced spatial distance skip a certain number of coils from the Y-axis direction of the sensor coils the transmission the process of receiving at Sensakoi Le other Y-axis direction, the Y-axis several repeated for one of the directions of the plurality sensor coils, the tablet of the position indicator by processing a received signal obtained as a result A sensor coil scanning method characterized by detecting coordinate information with respect to.   3. The sensor coil scanning method according to claim 1, wherein the number of skipping coils is one.   3. The sensor coil scanning method according to claim 1, wherein the number of skipping the coils is two.   3. The sensor coil scanning method according to claim 1, wherein the number of skipping the coils is three.

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