JP2004029915A - Electronic writing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an electronic writing system in which the error of measuring the position of a stylus point P<SB>0</SB>of a writing means is more reduced. <P>SOLUTION: As for this electronic writing system for measuring a position on a writing face WS of the stylus point P<SB>0</SB>of the writing means, at least two points P<SB>1</SB>and P<SB>2</SB>to be measured are set so that the stylus point P<SB>0</SB>and these parts P<SB>1</SB>and P<SB>2</SB>can be arranged on an almost straight line in the writing means. A measuring means measures the positions of these parts P<SB>1</SB>and P<SB>2</SB>, and a calculating means calculates the position of the point P<SB>0</SB>on the writing face WS based on the positions of the points P<SB>1</SB>and P<SB>2</SB>measured by the measuring means and a distance relation between the points P<SB>0</SB>and the parts P<SB>1</SB>and P<SB>2</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic writing system that can suitably support information sharing.
[0002]
[Prior art]
2. Description of the Related Art Recently, an electronic writing system capable of recording characters, figures, illustrations, and other written contents written on a notebook, a whiteboard, or the like has been developed. Such an electronic writing system tracks the movement of the tip of a writing means used for writing and converts the movement into digital data.
[0003]
[Problems to be solved by the invention]
By the way, when a person performs a writing action, the writing means moves up, down, left and right on the writing surface, and the writing means tilts up, down, left, and right. In particular, when writing Japanese characters, the change in the inclination of the writing means when the tip is moved is large compared to writing in English or the like. Then, when measuring the position of the writing tip of the writing means, if the inclination of the writing means changes, an error occurs in the measurement. To give a specific example, in a system in which the position of a predetermined measurement target point set in the writing means is repeatedly measured to obtain a time series of the coordinate data, the writing tip is changed according to a change in the inclination of the writing means. The positional relationship between the object and the measurement target point changes. That is, the coordinates of the writing tip are not uniquely determined from the coordinates of the measurement target point, and the coordinates of the writing tip cannot be calibrated based on the magnitude and direction of the inclination of the writing means. Therefore, when the inclination of the writing means changes, an error occurs in the measurement of the position of the writing tip. As a result, the accuracy of tracking the movement of the brush tip and, consequently, the accuracy of recording the written contents have been reduced.
[0004]
In view of the above problems, an object of the present invention is to realize an electronic writing system in which the measurement error in measuring the position of the writing tip of the writing means is reduced.
[0005]
[Means for Solving the Problems]
In order to solve the problems described above, according to the present invention, in an electronic writing system that repeatedly measures a position of a writing tip of a writing means on a writing surface to obtain a time series of coordinate data of the writing tip, the writing means may include at least two points. The two measurement target parts are set so that the pen tip and each of these measurement target parts are substantially on a straight line, the measuring means measures the position of each measurement target part, and the calculating means measures by the measuring means. The position of the writing tip on the writing surface is calculated based on the position of each measurement target part and the distance relationship between the writing tip and each measurement target part.
[0006]
That is, the position of the plurality of measurement target portions set in the writing means is measured, and the position of the writing tip is calculated based on the plurality of measured values, thereby measuring the position of the writing tip with a change in the inclination of the writing means. The error was reduced. With such a configuration, it is possible to further improve the accuracy of tracking the movement of the writing tip and to reliably record the writing contents. In particular, the electronic writing system functions effectively even when writing in Japanese.
[0007]
In addition, the writing surface generally refers to a target to which the writing tip of the writing means is brought into contact when performing a writing operation or the like. Applicable. The writing surface is generally substantially flat, but the orientation is not particularly limited. The distance relationship between the writing tip and each measurement target portion refers to information that is known in advance and that can guide knowledge about the respective distances between each measurement target portion and the writing tip.
[0008]
As a method of measuring the position of the measurement target part set in the writing means, the distance between at least two observation parts provided in the measurement means and the measurement target part is measured, and the measurement target part is measured using a triangulation method. That determine the position of the The distance between the observation unit and the measurement target unit is measured by measuring the time from when one of the observation unit and the measurement target unit transmits a measurement signal to when the other receives the measurement signal. It is possible by measuring. At this time, it is preferable that the measurement signal be a sound wave as a signal medium.
[0009]
If one of the measuring means and the writing means also transmits a timing signal at substantially the same time as the transmission of the measurement signal and the other also receives the timing signal, the time at which the measurement signal was transmitted is measured. The means can be known. Since it is desirable that this timing signal has a sufficiently high propagation speed, it is preferable to use an electromagnetic wave as a signal medium.
[0010]
Further, it is easy to measure the positions of the plurality of measurement target units in a time-division manner.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The electronic writing system according to the present invention exerts its effect by making the writing means, the measuring means, and the calculating means 32 cooperate. FIG. 1 shows an example of the configuration of an electronic writing system. The electronic writing system according to the present embodiment uses a writing surface WS, for example, a measuring device 2 installed on a peripheral portion of a board surface of a whiteboard, and an information processing device 3 connected to the measuring device 2 to write information. Brush point P₀Is repeatedly measured on the writing surface WS.
[0012]
The writing means is used directly by a user who performs a writing operation or the like, and uses the writing device 1. The writing device 1 is configured as a device having a function as a writing instrument or as an optional product attached to a ready-made writing instrument. The writing implements referred to herein generally include various pens, pencils, fountain pens, writing brushes, chalks, and the like. In the illustrated example, a writing device 1 in the form of a holder capable of accommodating the marker pen is attached to the marker pen to provide writing means. As shown in FIG. 2, the writing device 1 includes a writing action sensing unit 11, at least two measurement target units 121 and 122, a timing signal transmission unit 13, and a control unit 14.
[0013]
The writing action sensing unit 11 senses that a writing action is being performed, in other words, the writing point P of the writing means.₀Is for detecting that the writing surface WS is in contact with the writing surface WS, and includes a sensor 11a for detecting the writing pressure and the like. In addition, the writing action detecting unit 11₀Is informed to the control unit 14 by an electrical method as to whether or not is touching the writing surface WS.
[0014]
The positions of the measurement target portions 121 and 122 are repeatedly measured by the measurement means. The writing device 1 according to the present embodiment includes two measurement target portions 121 and 122,₀And the measurement target portions 121 and 122 are set to be substantially on a straight line. Brush point P₀The distance relationship between the measurement target units 121 and 122 is known. That is, the brush point P₀Is given as a known constant to the distance between each of the measurement target portions 121 and 122,₀And the distance between the measurement target portions 121 and 122 can be derived from a known constant. In addition, each measurement target section 121, 122 is provided with a function of transmitting measurement signals M1, M2. In the present embodiment, the measurement signals M1 and M2 use a sound wave, particularly an ultrasonic wave as a signal medium. Therefore, each of the measurement target units 121 and 122 includes the ultrasonic transmitters 121a and 122a. The measurement signals M1 and M2 transmitted from the measurement target units 121 and 122 are received by an observation unit provided in the measurement unit.
[0015]
The timing signal transmitting section 13 transmits a timing signal T. In the present embodiment, the timing signal T uses an electromagnetic wave, particularly an infrared ray as a signal medium. Therefore, the timing signal transmitting unit 13 includes the infrared signal transmitting device 13a. The timing signal T transmitted by the timing signal transmitting unit 13 is received by the timing signal receiving unit 23 provided in the measuring unit.
[0016]
The control unit 14 controls the timing at which the measurement target units 121 and 122 transmit the measurement signals M1 and M2 and the timing signal transmission unit 13 transmits the timing signal T. An example of control of the measurement target units 121 and 122 and the timing signal transmission unit 13 by the control unit 14 will be described with reference to a timing chart illustrated in FIG. The control unit 14 in the example illustrated in FIG. 2 includes a control circuit 14a that sends out two control signals S2 and S3, a measurement signal generation circuit 14b that generates a signal based on the measurement signals M1 and M2, and the like. I have. The control circuit 14a includes a writing point P of the writing means.₀While the writing action sensing unit 11 senses that the contact is in contact with the writing surface WS, it sends out the control signals S2 and S3. Each of the control signals S2 and S3 transmitted by the control circuit 14a is, for example, a periodic pulse having a required pulse width. A time difference is provided between one control signal S2 and the other control signal S3. The measurement signal generation circuit 14b supplies the signal S1 for driving the ultrasonic transmitters 121a and 122a of the respective measurement target units 121 and 122, and the measurement signal generation circuit 14b and each of the ultrasonic transmitters 121a and A gate is interposed between the ultrasonic transmitters 122a and 122a, and the signal S1 is sent to the ultrasonic transmitters 121a and 122a (as signals S4 and S5) only during a period in which the gate is opened by the pulses of the control signals S2 and S3. It can be supplied. The control circuit 14a also sends out the control signals S2 and S3 to the infrared signal transmission device 13a of the timing signal transmission unit 13. The infrared signal transmitting device 13a transmits the timing signal T in synchronization with the rising of the pulse of the control signals S2 and S3 (the signal S6). As a result, the writing point P₀Is in contact with the writing surface WS, one of the measurement target portions 121 and the other measurement target portion 122 transmit the measurement signals M1 and M2 in a time-division manner, and the timing signal transmission portion 13 transmits these measurement signals M1 and M1. The timing signal T is transmitted almost simultaneously with the transmission of M2. The transmission of the measurement signals M1 and M2 and the timing signal T₀Is repeatedly performed as long as is in contact with the writing surface WS.
[0017]
Incidentally, a plurality of writing means can be used together in a single electronic writing system. For example, the ink color and the brush tip P₀A plurality of writing means having different thicknesses or the like can be selectively used. In such a case, the ink color and the brush tip P₀It is preferable that the additional information for identifying the thickness or the like is transmitted from the writing means to the measuring means. The additional information can be transmitted as an infrared signal from the infrared signal transmitting device 13a together with the timing signal T or separately from the timing signal T, for example.
[0018]
The measuring means measures the position of each of the measurement target parts 121 and 122 set in the writing means. The measuring means includes at least the measuring device 2 as a component thereof. The measuring device 2 is usually attached to the periphery of the writing surface WS. In the illustrated example, the measuring device 2 is attached to the periphery of the white boat. The measuring device 2 is configured to be connected to an information processing device 3 typified by a personal computer so as to exchange data. Then, the measuring device 2 includes at least two observing units 21 and 22, a timing signal receiving unit 23, and a measuring unit 24, as shown in FIG.
[0019]
The observation units 21 and 22 serve as a reference when measuring the positions of the measurement target units 121 and 122 set in the writing unit. The measuring device 2 according to the present embodiment includes two fixed observation units 21 and 22. The distance between the two observation units 21 and 22 is given as a known constant or is derived from the known constant. Therefore, by measuring the respective distances between the observation units 21 and 22 and the measurement target units 121 and 122, the positions of the measurement target units 121 and 122 can be determined. Each of the observation units 21 and 22 is provided with a function of receiving measurement signals M1 and M2 transmitted from the measurement target units 121 and 122. As described above, in this embodiment, the measurement signals M1 and M2 use a sound wave, particularly an ultrasonic wave as a signal medium. Therefore, each of the observation units 21 and 22 includes the ultrasonic receivers 21a and 22a.
[0020]
The timing signal receiving unit 23 receives a timing signal T transmitted from the writing device 1. As described above, in the present embodiment, the timing signal T uses an electromagnetic wave, particularly an infrared ray as a signal medium. Therefore, the timing signal receiving unit 23 includes the infrared signal receiving device 23a.
[0021]
The measurement unit 24 measures the distance between each of the observation units 21 and 22 and the measurement target units 121 and 122. In the present embodiment, the measurement units 121 and 122 measure the time from when the measurement signals M1 and M2 are transmitted to when the observation units 21 and 22 receive the measurement signals M1 and M2. The distance between 22 and the measurement target parts 121 and 122 is measured. An example of the measurement of the propagation times of the measurement signals M1 and M2 by the measurement unit 24 will be described with reference to the timing chart of FIG. The measuring unit 24 in the example shown in FIG. 4 includes the same number of timers 24a and 24b as the observing units 21 and 22, a clock generation circuit 24c that supplies clock pulses to the timers 24a and 24b, and synchronization with the reception of the measurement signals M1 and M2. Detection circuits 24d, 24e for inputting stop signals S7, S8 to the timers 24a, 24b, buffers 24f, timers 24a, 24b, and buffers for sending the measurement values measured by the timers 24a, 24b to the external information processing device 3. A control circuit 24g for sending various control signals to 24f and the like is provided. The timers 24a and 24b measure the times ta1, tb1, ta2 and tb2 from when the start signal is input to when the stop signals S7 and S8 are input. More specifically, the timers 24a and 24b stop after the start signal is input. It counts the number of clocks until the signals S7 and S8 are input. The start signal is input by the control circuit 24g, and the stop signals S7 and S8 are input by the detection circuits 24d and 24e. The measurement values measured by the timers 24a and 24b are sent to the buffer 24f. The detection circuits 24d and 24e are interposed between the ultrasonic receivers 21a and 22a of the observation units 21 and 22 and the timers 24a and 24b, and when the ultrasonic receivers 21a and 22a receive the measurement signals M1 and M2. , And sends stop signals S7 and S8 to the timers 24a and 24b. The detection circuits 24d and 24e, for example, amplify and detect the reception signals provided from the ultrasonic receivers 21a and 22a, and then generate stop signals S7 and S8 in the form of square pulses through a Schmitt trigger circuit, and send them to the timer 24a. , 24b. In addition, the stop signals S7 and S8 output from the detection circuits 24d and 24e are also provided to the control circuit 24g. The control circuit 24g sends a start signal to both timers 24a and 24b when the infrared signal receiver 23a of the timing signal receiver 23 receives the timing signal T. The start signal substantially synchronizes, for example, the moment when the timing signal T rises with the start of measurement by the timers 24a and 24b.
[0022]
In other words, the timing signal T transmitted from the writing means in the form of an infrared signal is used as a signal to start measurement, and the measurement signal M1 transmitted in the form of an ultrasonic signal from the measurement target unit 121 reaches the observation unit 21. Can be measured by the timer 24a, and the time tb1 until reaching the observation unit 22 can be measured by the timer 24b. When the measurement by the timers 24a and 24b is completed, that is, when the stop signals S7 and S8 are provided from the detection circuits 24d and 24e, the control circuit 24g sends a control signal to the buffer 24f. The buffer 24f that has received the control signal sends the measured value to the external information processing device 3 via the interface 25. After sending the measured values, the control circuit 24g inputs a reset signal to both timers 24a and 24b to reset the counters of the timers 24a and 24b. However, the reset signal may be input to the timers 24a and 24b together with the start signal. Similarly, using the timing signal T transmitted from the writing means as a signal to start the measurement, the time ta2 until the measurement signal M2 transmitted from the measurement target unit 122 reaches the observation unit 21 is measured by the timer 24a. The time tb2 until reaching the unit 22 can be measured by the timer 24b.
[0023]
Furthermore, the measuring means in the present embodiment also includes the information processing device 3 connected to the measuring device 2 as a constituent element. As shown in FIG. 5, for example, the information processing apparatus 3 includes a processor 3a, a main memory 3b, an auxiliary storage unit 3c represented by a hard disk drive, a display control unit 3d including a graphics chip, a video memory, and the like. A communication interface 3e for exchanging data with the device is controlled by control devices, that is, a system controller 3f and an I / O controller 3G, and operates in cooperation with each other. The system controller 3f is interposed between the processor 3a bus of the processor 3a, the memory bus of the main memory 3b, and the like, and includes a PCI bridge and a memory controller. The I / O controller 3G controls exchange between the processor 3a and peripheral devices. Normally, a program to be executed by the processor 3a is stored in the auxiliary storage means 3c. When the program is executed, the program is read from the auxiliary storage means 3c into the main memory 3b and decoded by the processor 3a. Then, the above-mentioned hardware resources are operated according to the program, so that at least the function as the position determining unit 31 shown in FIG. 6 is exhibited.
[0024]
The position determination unit 31 determines the positions of the measurement target units 121 and 122 from the measured values of the distances between the observation units 21 and 22 and the measurement target units 121 and 122. As described above, since the distance between the two observation units 21 and 22 is known, the measurement target unit 121 and the measurement target unit 121 are determined using a triangulation method using a line connecting the two observation units 21 and 22 as a base line. It is possible to determine the position of 122. The position determination unit 31 uses the two measurement values provided from the buffer 24f of the measurement unit 24 via the interface 25 and the communication interface 3e, and the value of the distance between the observation units 21 and 22 to determine the measurement target unit. The relative positions of 121 and 122 with respect to observation units 21 and 22 are calculated, and their coordinate data is obtained. The position determination unit 31 in the present embodiment is mainly configured by software. Since the writing means includes a plurality of measurement target parts 121 and 122, the measurement means measures the position of each of the measurement target parts 121 and 122 and determines the position of each of the measurement target parts 121 and 122. It is necessary to obtain a set of coordinate data. In this embodiment, the writing point P of the writing means₀As long as is in contact with the writing surface WS, the measurement of each distance between one measurement target unit 121 and the two observation units 21 and 22 and the measurement between the other measurement target unit 122 and the two observation units 21 and 22 are performed. The measurement of each distance is performed alternately and repeatedly by the measuring unit 24. Therefore, the position determination unit 31 sets two sets of coordinate data calculated from the measurement values continuously provided by the measurement unit 24 as a set, and stores the set in the required storage area of the main memory 3b or the auxiliary storage unit 3c. .
[0025]
That is, the measurement unit in the present embodiment utilizes the functions of the measurement device 2 and the information processing device 3 and includes observation units 21 and 22, a timing signal reception unit 23, a measurement unit 24, and a coordinate determination unit 31. .
[0026]
Incidentally, the propagation speed of the sound wave in the air changes depending on the temperature. Therefore, in order to always perform highly accurate measurement, a temperature sensor or the like (not shown) is provided in the measurement device 2 or the information processing device 3 which is a component of the measurement unit, and the temperature of the temperature sensor is measured. It is desirable to calibrate the measurement of the distance between the measurement target units 121 and 122 and the observation units 21 and 22 based on the measurement values.
[0027]
Then, the calculating means 32 calculates the positions of the measurement target parts 121 and 122 measured by the measuring₀Based on the distance relationship between the₀Is calculated on the writing surface WS. In the present embodiment, the calculating means 32 uses the information processing device 3 connected to the measuring device 2. The calculation means 32 includes a tip coordinate calculation unit 321 and a tip coordinate storage unit 322.
[0028]
The writing point coordinate calculation unit 321 calculates the writing point P based on the coordinate data of the positions of the measurement target units 121 and 122 of the writing means measured by the measurement means.₀Is calculated, and its coordinate data is obtained. The writing point coordinate calculation unit 321 in the present embodiment is mainly configured by software.
[0029]
The writing point coordinate storage unit 322 is configured by using a required storage area of the main memory 3b or the auxiliary storage unit 3c.₀The coordinate data of is stored. Measurement of the position of each of the measurement target portions 121 and 122 set in the writing means and the writing point P₀Calculation of the position of₀Is repeatedly performed as long as it is in contact with the writing surface WS, and the writing point coordinate storage unit 322 stores the time-series coordinate data obtained as a result. Brush point P₀Is the stroke data of one stroke (writing tip P)₀(From contact with the writing surface WS to separation from the writing surface WS).
[0030]
The time-series coordinate data stored in the writing point coordinate storage unit 322 can be used for storing writing contents in writing using writing means, reproducing a writing action, and the like. Of course, characters, figures, illustrations, and the like written on the writing surface WS can be expressed on the display of the information processing device 3. In addition, the ink color and brush point P₀In the case where additional information for identifying the thickness or the like is transmitted from the writing unit, the measuring unit receives the additional information, and the additional information and the writing point P are stored in the writing point coordinate storage unit 322.₀Can be stored in association with the coordinate data. In such a case, the ink color and the brush tip P together with the written contents written on the writing surface WS are used.₀Can be reproduced.
[0031]
Note that the position determination unit 31, the tip coordinate calculation unit 321, and the tip coordinate storage unit 322 may be included in the measurement device 2. Further, the measuring unit 24 may be included in the information processing device 3.
[0032]
Thereafter, the distance between the two observing units 21 and 22 included in the measuring unit and the two measurement target units 121 and 122 set in the writing unit is measured, and thereby the writing point P of the writing unit is measured.₀Indicates that the position of can be uniquely determined.
[0033]
As shown in FIG. 7, the tip P of the writing means in the three-dimensional Euclidean space₀Coordinate of P₀(X₀, Y₀, 0), the coordinates of the two measurement target parts 121 and 122 are P₁(X₁, Y₁, Z₁), P₂(X₂, Y₂, Z₂)far. Here, the writing surface WS; z = 0, and three points P of the writing means₀, P₁, P₂Is in the region of z> 0. In addition, brush point P₀And each measurement target part P₁, P₂Is known, and P₀And P₁Distance to ka, P₀And P₂Is a (where 0 <k <1). a and k are known constants.
[0034]
On the other hand, the coordinates of the two observation units 21 and 22 of the₄(0,0, m), P₅(0, l, m). l is two observation points P₄, P₅, M is the observation point P₄, P₅And the writing surface WS, which are known constants. However, the observation part P₄From the observation surface P to the writing surface WS₅Does not prevent the distance from the writing surface WS to the writing surface WS from being different.
[0035]
At this time, the measurement target part P₁And observatory P₄D is the measured value of the distance to₁₁, Measurement target part P₁And observatory P₅D is the measured value of the distance to₁₂After all,
d₁₁ ²= X₁ ²+ Y₁ ²+ (Z₁-M)²
d₁₂ ²= X₁ ²+ (Y₁−l)²+ (Z₁-M)²
Holds. Similarly, the measurement target part P₂And observatory P₄D is the measured value of the distance to₂₁, Measurement target part P₂And observatory P₅D is the measured value of the distance to₂₂After all,
d₂₁ ²= X₂ ²+ Y₂ ²+ (Z₂-M)²
d₂₂ ²= X₂ ²+ (Y₂−l)²+ (Z₂-M)²
Holds.
[0036]
Also, two measurement target parts P₁, P₂About the distance between
(A-ka)²= (X₂-X₁)²+ (Y₂-Y₁)²+ (Z₂-Z₁)²
Holds.
[0037]
In addition, brush point P₀And each measurement target point P₁, P₂Are arranged substantially on a straight line, or in the measurement of the position of the tip P0, the tip P₀And each measurement target point P₁, P₂Can be considered to be aligned. Further, when a writing action is being performed, the writing point P₀Is in contact with the writing surface WSz = 0,
z₁= Kz₂
Holds.
[0038]
As described above, the six unknowns x₁, Y₁, Z₁, X₂, Y₂, Z₂Since six equations hold for d₁₁, D₁₁, D₂₁, D₂₂By measuring these unknowns x₁, Y₁, Z₁, X₂, Y₂, Z₂Can be determined. By the way, P₁, P₂When the coordinates are determined, it is not always necessary to use the analytic solution of the above simultaneous equations, and an approximate solution within an allowable range may be obtained.
[0039]
And two measurement target parts P₁, P₂Is determined, the writing point P of the writing means₀Can be calculated. That is,
x₀= (X₁-Kx₂) / (1-k)
y₀= (Y₁-Ky₂) / (1-k)
It becomes. Of course, P₀When the coordinates are determined, an approximate solution may be obtained within an allowable range.
[0040]
Therefore, according to the present embodiment, at least two measurement target portions 121 and 122 are added to the writing means by the writing point P.₀Are set so that they are substantially in line with each other, and the measuring means measures the position of each of the measuring objects 121 and 122, and the calculating means 32 measures the position by the measuring means. Position of each of the measurement target portions 121 and 122 and the tip P₀Based on the distance relationship between the₀Is configured to calculate the position on the writing surface WS of the writing surface WS.₀The measurement error of the position of the₀It is possible to further improve the accuracy of tracking the movement of the user and to reliably record the written contents. In particular, the electronic writing system functions effectively even when writing in Japanese. In addition, the measurement target portions 121 and 122 are₀Is not required to be set in the vicinity, the degree of freedom in designing the writing device 1 and the measuring device 2 is also increased.
[0041]
The measurement means includes at least two observation units 21 and 22, and measures the distance between each of the observation units 21 and 22 and the measurement target units 121 and 122 to determine the positions of the measurement target units 121 and 122. Since it is determined, it can be configured using an existing distance measuring device.
[0042]
The measuring means measures the time from when one of the observation units 21 and 22 and the measurement target units 121 and 122 transmits the measurement signals M1 and M2 to when the other receives the measurement signals M1 and M2. By doing so, the distance between the observation units 21 and 22 and the measurement target units 121 and 122 is measured, so that the configuration of the measurement device 2 can be simplified and the system does not need to be large.
[0043]
Since the measurement signals M1 and M2 use sound waves as a signal medium, existing ultrasonic transmission and reception devices can be used, and the configuration can be made at low cost. In addition, compared to the case where microwaves or the like are used as the signal medium, the influence on electronic devices and metals, or the influence of these, is small, and the pen tip₀Can be measured.
[0044]
If one of the measuring means and the writing means also transmits the timing signal T substantially simultaneously with the transmission of the measurement signals M1 and M2, and the other also receives the timing signal T, the timing signal T The time difference between the reception and the reception of the measurement signals M1 and M2 can be used as the arrival time of the measurement signals M1 and M2, and the side transmitting the measurement signals M1 and M2 receives only the signal transmission and receives the measurement signals M1 and M2. The receiving side only needs to perform signal reception processing. That is, there is no need to perform complicated communication between the writing device 1 and the measuring device 2, which leads to simplification of the internal configuration of the writing device 1 and the measuring device 2 and speeding up of processing.
[0045]
If the timing signal T uses an electromagnetic wave as a signal medium, the propagation speed is sufficiently high, so that the distance can be measured appropriately. Then, wireless communication between the writing means and the measuring means can be achieved. Further, it is also possible to execute transmission and reception of information such as additional information using the timing signal T as a carrier wave.
[0046]
If the measurement of one position and the measurement of another position among the plurality of measurement target units 121 and 122 are performed in a time-division manner, the measurement target units 121 and 122 and the observation units 21 and 22 are connected to each other. It is not necessary to set the respective measurement signals M1 and M2 transmitted and received between them to different frequencies or to add an identifier for identifying the respective measurement signals M1 and M2 to the measurement signals M1 and M2. The transmitter and the receiver of the measurement signals M1 and M2 can have a simple configuration, and there is no need to perform frequency modulation and demodulation and other complicated processes in transmission and reception of the measurement signals M1 and M2. No software resources are required. In addition, in the present embodiment, since the ultrasonic signals are used as the measurement signals M1 and M2, the positions of the plurality of measurement target units 121 and 122 are measured by the frequency division method, that is, each measurement target unit 121 and 122 If the measurement signals M1 and M2 transmitted and received between the observation units 21 and 22 are set to different frequencies, it is necessary to use the ultrasonic receivers 21a and 22a having different resonance frequencies. In the example of the present embodiment, the number of the ultrasonic receivers 21a and 22a to be provided in the measuring instrument 2, in other words, the number of the observation units 21 and 22 is doubled, and the manufacturing cost is increased. However, if the measurement of the positions of the plurality of measurement target units 121 and 122 is performed in a time-division manner as in the present embodiment, the number of the observation units 21 and 22 may be two, and the positions of the measurement target units 121 and 122 may be two. The observation units 21 and 22 can be shared in the measurement of.
[0047]
Note that the present invention is not limited to the embodiment described in detail above. In particular, transmission and reception of the measurement signal and the timing signal can take aspects other than the above embodiment. For example, if the writing device 1 that transmits a timing signal from the measurement device 2 and receives the measurement signal from the measurement target unit transmits the timing signal, the measurement device 2 transmits the timing signal, and then the measurement signal. You can measure the time until receiving. The measurement device 2 may transmit the measurement signal and measure the time until the measurement target unit set in the writing device 1 receives the measurement signal. Alternatively, the writing device 1 and the measuring device 2 may be connected by wire. In this case, transmission and reception of the timing signal and the like can be performed by wire.
[0048]
In addition, it does not prevent the measurement of the positions of the plurality of measurement target parts from being performed by a method other than time division.
[0049]
Further, the measurement of the position of the measurement target portion set in the writing means is not always performed by using the triangulation method. For example, the measuring means may optically observe the measurement target portion from a plurality of directions and directly measure the position.
[0050]
The electronic writing system of the present invention can be used in combination with a projector such as a personal computer that projects a display screen. More specifically, the projection screen of the projector is a writing surface WS, and the writing means is moved up, down, left, and right on the writing surface WS, and the writing point P is moved through the measuring means and the calculating means.₀Is fed back to the personal computer or the like, whereby the writing means can be used as a pointing device. The writing means in such a case does not necessarily leave ink, carbon powder, etc. on the writing surface WS.
[0051]
In addition, the specific configuration of each unit is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0052]
【The invention's effect】
According to the present invention described in detail above, it is possible to realize an electronic writing system in which the measurement error in measuring the position of the writing tip of the writing means is reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of an electronic writing system according to an embodiment of the present invention.
FIG. 2 is a block diagram of a writing unit according to the embodiment;
FIG. 3 is a timing chart of the electronic writing system according to the embodiment.
FIG. 4 is a block diagram of a measurement device according to the embodiment.
FIG. 5 is an exemplary view showing a hardware resource configuration of the information processing apparatus according to the embodiment;
FIG. 6 is a functional block diagram of the information processing apparatus.
FIG. 7 is a view for explaining measurement of a position of a writing tip by an electronic writing system.
[Explanation of symbols]
1. Writing equipment
121, 122 ... Measurement target part
2. Measurement equipment
21, 22… Observation unit
P₀… Brush tip
WS: Writing surface

Claims (9)

An electronic writing system for measuring a position of a writing means on a writing surface of a writing tip,
In the writing means, at least two measurement target portions are set such that the writing tip and each of the measurement target portions are substantially on a straight line,
Measuring means measures the position of each measurement target portion,
An electronic writing system, wherein the calculating means calculates a position of the writing tip on a writing surface based on a position of each measurement target part measured by the measurement means and a distance relationship between the writing tip and each measurement target part. 2. The electronic writing system according to claim 1, wherein the measurement unit includes at least two observation units, and determines a position of the measurement target unit by measuring a distance between each of the observation units and the measurement target unit. system. The measuring means measures a distance between the observation unit and the measurement target unit by measuring a time from when one of the observation unit and the measurement target unit transmits the measurement signal to when the other receives the measurement signal. 3. The electronic writing system according to claim 2, wherein the electronic writing system is configured to measure the value of the electronic writing. 4. The electronic writing system according to claim 3, wherein the measurement signal uses sound waves as a signal medium. The electronic writing system according to claim 3, wherein one of the measuring unit and the writing unit also transmits a timing signal substantially simultaneously with the transmission of the measurement signal, and the other receives the timing signal. The electronic writing system according to claim 5, wherein the timing signal uses electromagnetic waves as a signal medium. The electronic writing system according to claim 1, wherein the measurement of one position and the measurement of another position of the plurality of measurement target units are performed in a time-sharing manner. A method of measuring a position of a writing means on a writing surface of a writing tip,
Measuring the positions of at least two measurement target portions set so that the writing tip is substantially on a straight line;
Calculating the position of the writing tip on the writing surface based on the position of each measurement target part measured by the measuring means and the distance relationship between the writing tip and each measurement target part. . A writing device, which is used for configuring the electronic writing system according to claim 1, 2, 3, 4, 5, 6, or 7, and includes at least two measurement target units.

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