JPH10149251A - Pen input device and positional coordinate correcting method for the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pen input device and a positional coordinate correcting method capable of preventing the generation of a deviation on positional coordinates due to the misreception of a top wave of an ultrasonic wave at a high response. SOLUTION: An ultrasonic wave transmitted from an ultrasonic wave sender of an input pen 1 is received by ultrasonic wave receiving elements 31a, 31b, a distance between the sender and the receiving elements 31a, 31b is calculated by a reception processing part 32 based on time required from the sending of the ultrasonic wave up to its reception and the distance is sent to an arithmetic processing part 40 through a communication part 33. The processing part 40 calculates the positional coordinates of the input pen 1 by the use of the inputted distance data and displays the calculated result on a display part 50. At the time the processing part 40 compares past measurement data with current measurement data, and when its difference coincides with one wavelength of the ultrasonic wave, the current measurement data are substituted for the past measurement data and reculcuiates the positional coordinates of the input pen 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pen input device in a computer system or the like having a handwriting input function, and more particularly, to a pen for detecting the position coordinates of an input pen using ultrasonic waves and inputting a designated position of the input pen. The present invention relates to an improvement in a processing method for correcting a positional coordinate shift due to a reception error of the leading wave of the ultrasonic wave in the input device.

[0002]

2. Description of the Related Art Conventionally, input devices in a computer system or the like having a handwriting input function include: 1) an infrared type; 2) a pressure-sensitive type; 3) a capacitive type; 4) an electromagnetic type; An ultrasonic type is known.

[0003] In the infrared method of 1), a spot position detected by a light pen that emits infrared light is detected using a semiconductor position detecting element, and a plurality of infrared light emitting elements and a light receiving element are arranged on an input surface. There is known a device that detects an indicated position by determining a position where infrared light emitted from an infrared light emitting element is blocked by a finger, an input pen, or the like from an output of the light receiving element.

[0004] In the pressure sensing method of 2), an electrode sheet provided with a plurality of X-axis electrodes and a plurality of Y-electrodes are arranged.
A pressure-sensitive panel in which a support on which an axis electrode is disposed is overlapped with a dot spacer interposed therebetween,
Sheets are superimposed via a three-dimensional spring,
2. Description of the Related Art There is known a device that detects a designated position by detecting a change in current at a position touched by a finger, an input pen, or the like.

[0005] In the case of the method of 3), the conductive films formed by vapor deposition on two sheets of glass are used as X-axis and Y-axis electrode patterns, respectively. A device using a capacitive coupling type panel in which surfaces are bonded to each other is known.

Further, according to the electromagnetic method of 4), a plurality of sensor antenna coils are arranged on an input surface, and a resonance circuit including a coil and a capacitor is built in an input pen. A current is caused to flow through the resonance circuit of the input pen using electromagnetic induction by flowing an alternating current through the coil, and then the alternating current flowing through the plurality of sensor antenna coils is turned off. There is known a device that detects a pointing position of an input pen by detecting a magnetic field generated by a current flowing through a resonance circuit with the plurality of sensor antenna coils.

[0007] In the ultrasonic method of 5), a) an ultrasonic vibration element and an ultrasonic receiving element for generating an ultrasonic surface acoustic wave are provided on a glass substrate to absorb an elastic wave of a finger or the like. An ultrasonic surface acoustic wave system for detecting the presence of a body from a change in the reception signal of the ultrasonic receiving element. B) As disclosed in JP-A-64-10319, at least two A set of ultrasonic transceivers is mounted, and ultrasonic waves transmitted from the ultrasonic transceivers of each set are reflected by a stylus pen indicating a desired position on the screen panel, and are transmitted by the ultrasonic transceivers of the set. The position on the screen panel indicated by the stylus pen is calculated and calculated from the time until it is received. C) The method disclosed in Japanese Utility Model Application Laid-Open No. 64-7340. As there,
Microphones are arranged at three or more known points on the same plane, and a sounding body which can be placed at an arbitrary coordinate position on the plane is provided, and a voltage generated at two microphones among the microphones is measured. It is known that a position of a hyperbola including the sounding body is determined from a time difference, and a coordinate position of the sounding body is determined from two or more intersections of the hyperbola.

However, the conventional input devices 1) to 4) have a problem that the structure is complicated and the manufacturing cost is high. In addition, it is difficult to apply an arbitrary size and type of input surface (display).

Also, the method 5) a) has a problem that its production is difficult and the production cost is high.
As in 4), there is a problem that it is difficult to apply it to an input surface (display) of any size and type.

[0010] Furthermore, in the case of item 5) b), it is impossible to distinguish between the stylus pen and the hand of the operator, and there is a problem that a malfunction is likely to be caused due to this. In the case of 5) c), it is necessary to arrange at least three microphones, for example, in order to detect the designated position on the two-dimensional coordinates of the stylus pen, and the processing becomes complicated. There's a problem. Also, it is difficult to realize a multi-pen function that enables the use of a plurality of input pens.

Therefore, nowadays, the ultrasonic transmitting means is mounted on the stylus pen, and the ultrasonic receiving means is arranged at a predetermined position in the input area of the stylus pen. The distance between the ultrasonic transmitting means and the ultrasonic receiving means is measured from the time when the ultrasonic wave is transmitted and the time when the ultrasonic wave is received by the ultrasonic receiving means, and the stylus pen is used by using the measured distance. An ultrasonic position detecting mechanism has been realized in which two-dimensional or three-dimensional position coordinates are calculated, and a position indicated by a stylus pen in a predetermined input area is input based on the calculated position coordinates.

[0012]

With the above configuration,
Generally, the ultrasonic wave transmission timing from the stylus pen is controlled so as to transmit an ultrasonic wave having a predetermined frequency for a certain period at a certain interval. Observing this from the receiving side, an ultrasonic wave of a predetermined frequency is received for a certain period at a certain period, but at this time, there is a risk that the leading wave of the ultrasonic wave may be missed at each reception timing. is there. This is mainly due to the amplifying ability of the amplifier section of the receiving circuit section, and is a problem peculiar to the position detecting mechanism using ultrasonic waves.

In this case, an error occurs in the measurement distance between the ultrasonic transmission / reception means due to the loss of the leading wave, and the position coordinates of the stylus pen are calculated using the incorrect measurement distance. In the case where the cursor is displayed in correspondence with the coordinate position of the stylus pen, a phenomenon similar to a shaky hand-shake of the cursor may occur even though the stylus pen is stopped.

In order to solve this problem, conventionally, for example, coordinate values calculated in the past are sampled retroactively to a plurality of reception timings, and an average value of the plurality of sampled data is calculated. Thus, there has been a method of correctly correcting the calculated value of the position coordinates.

However, according to such a conventional correction method, a sufficient response to the movement of the stylus pen is obtained due to the processing of sampling the past calculated coordinate values up to a plurality of times before and taking the average value of these values. However, there is a problem that the correction with the error cannot be performed.

As a general method of correcting the measured distance in this type of position detection mechanism, as disclosed in Japanese Patent Application Laid-Open No. 7-64696, 6) Immediately before the coordinate Pi read from the position detection mechanism. The detected coordinates Pi-1 and the coordinates Pi + 1 detected immediately after the coordinates Pi
To determine the validity of Pi from
No. 75821, JP-A-63-14220, JP-A-4-38510, JP-A-8-16308, etc. 7) For a stylus pen equipped with an ultrasonic transmitter At least two or three ultrasonic receivers are arranged, and an ultrasonic position detecting mechanism for detecting the two-dimensional or three-dimensional position coordinates of the stylus pen is premised. The minimum number of ultrasonic receivers required There is known an ultrasonic receiver which is additionally provided to improve the detection accuracy of the position coordinates of the stylus pen.

However, the method 6) is intended to prevent an erroneous input due to suddenly generated electrical noise or the like, and as described above, the measurement is performed due to the reception error of the leading ultrasonic wave. It was impossible to cope with a distance measurement error that is unique to this type of ultrasonic position detection mechanism, which causes an error in the distance.

In the case of item (7), the detection accuracy itself can be improved by providing more ultrasonic receivers than necessary, but no measures are taken to prevent the leading wave from being missed by the ultrasonic receiver. As a result, as in the case of 6), it was impossible to cope with a distance measurement error peculiar to the ultrasonic position detecting mechanism caused by a head wave reception error. In this type of ultrasonic position detecting mechanism, it is desired that the ultrasonic receiver be small and simple in mounting the ultrasonic receiver on the input surface.
In the case of 7) in which more ultrasonic receivers are provided than the required number, there is a problem that the product value is reduced in this respect.

Therefore, in the present invention, it is possible to prevent displacement of the position coordinates of the input pen due to erroneous measurement of the distance between the ultrasonic transmitting / receiving means when the leading wave of the ultrasonic wave transmitted from the ultrasonic transmitting means is missed. An object of the present invention is to provide a pen input device capable of responding with good response and a position coordinate correction method in the device.

[0020]

In order to achieve the above-mentioned object, a pen input device according to the present invention uses a time when an ultrasonic wave is transmitted from an ultrasonic transmitting means mounted on an input pen and an ultrasonic receiving means. A distance measuring means for measuring a distance between the ultrasonic transmitting means and the ultrasonic receiving means from a time at which the ultrasonic wave is received;
Calculating means for calculating three-dimensional or three-dimensional position coordinates, and a pen input device for inputting a position indicated by the input pen in a predetermined input area based on the position coordinates calculated by the calculating means; A measurement distance storage unit that stores a measurement distance between the ultrasonic transmission unit and the ultrasonic reception unit, and a comparison unit that compares a past measurement distance and a current measurement distance stored in the measurement distance storage unit. When the difference between the past measurement distance and the current measurement distance is equal to one wavelength of the ultrasonic wave, the current measurement distance is abandoned, and correction means for giving the past measurement distance to the calculation means. It is characterized by having.

In this pen input device, the comparison result of the comparison means is monitored, and the comparison result that the difference between the past measurement distance and the current measurement distance is equal to one wavelength of the ultrasonic wave is continuously N. If (N is a natural number) times, the past measurement distance is abandoned and the current measurement distance may be provided to the calculation means.

Further, the position coordinate correcting method in the pen input device according to the present invention is characterized in that the ultrasonic wave transmitting means mounted on the input pen transmits ultrasonic waves, and the ultrasonic receiving means receives the ultrasonic waves. Measuring the distance between the ultrasonic transmitting means and the ultrasonic receiving means from the input pen, calculating the two-dimensional or three-dimensional position coordinates of the input pen using the measured distance, and calculating the input pen in a predetermined input area. In the pen input device for inputting the pointing position according to, the measured distance between the ultrasonic transmitting means and the ultrasonic receiving means in the past is stored, and the stored past measured distance is compared with the current measured distance. If the difference between the past measurement distance and the current measurement distance is equal to one wavelength of the ultrasonic wave, the current measurement distance is discarded, and the previous measurement distance is used using the past measurement distance. And calculates the position coordinates.

In the position coordinate correcting method in the pen input device, the comparison result that the difference between the past measured distance and the present measured distance is equal to one wavelength of the ultrasonic wave is continuously N (N is When the number is obtained (natural number) times, the use of the past measurement distance is stopped, and the position coordinates are calculated using the current measurement distance.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pen input device according to the present invention comprises:
The transmission timing of the ultrasonic waves transmitted from the ultrasonic transmission means provided on the input pen is synchronized with the reception timing of the ultrasonic reception means for receiving the ultrasonic waves transmitted from the ultrasonic transmission means. Above, the distance between the ultrasonic transmitting means and the ultrasonic receiving means is calculated from the time difference between the timing at which the ultrasonic wave is transmitted from the ultrasonic transmitting means and the timing at which the ultrasonic wave is received by the ultrasonic receiving means, Further, the position coordinates of the input pen are calculated using the distance between the ultrasonic transmission unit and the reception unit, and the position indicated by the input pen in a predetermined input area such as a display of a personal computer is input using a cursor or the like. This is based on the premise of an ultrasonic position detecting mechanism.

In particular, in the present invention, in the above-mentioned ultrasonic position detecting mechanism, in order to prevent a displacement of a designated position caused by an erroneous measurement of a distance between an ultrasonic transmitting unit and a receiving unit due to a reception error of a leading ultrasonic wave. The distance data already measured is stored, and thereafter, each time the distance data is measured, the current measurement data is compared with the stored past measurement data, and these differences are used in the mechanism. If it coincides with one wavelength of the ultrasonic wave, it is determined that the reception of the leading wave of the ultrasonic wave is a mistake,
It has a measurement distance correction processing function of replacing current measurement data with past measurement data and recalculating the position coordinates of the input pen.

According to the correction processing function, whether the leading wave of the ultrasonic wave could not be received depends on whether the difference between the past measured data and the present measured data corresponds to one wavelength of the ultrasonic wave or not. Recognize whether or not the leading wave of the ultrasonic wave could not be received, because the position coordinates of the input pen are recalculated using the past measurement data correctly measured with the reception of the leading wave In addition, an erroneous measurement distance between the ultrasonic transmission unit and the reception unit due to a reception error of the leading wave can be correctly corrected each time, and the displacement of the position indicated by the input pen can be reliably prevented.

Hereinafter, embodiments of a pen input device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an information processing apparatus configured by applying a pen input device according to the present invention. This information processing apparatus uses an input pen (hereinafter referred to as a stylus pen) 1 to display a display unit 5.
The image corresponding to the designated position designated on the display screen 0 is displayed on the display screen of the display unit 50.

In this embodiment, the stylus pen 1 is provided with an ultrasonic transmitting means for outputting ultrasonic waves from its tip, as will be described in detail later. The designated position on the display screen of the display unit 50 is detected based on the detected position, and an image corresponding to the designated position is displayed on the display screen of the display unit 50.

That is, the information processing apparatus according to the present embodiment includes two ultrasonic receiving elements 31a and 31b for receiving ultrasonic waves generated from the stylus pen 1, and two ultrasonic receiving elements 31a and 31b. An ultrasonic receiving unit 30 that processes a reception output, an arithmetic process that calculates a position indicated by the stylus pen 1 based on a processing result of the ultrasonic receiving unit 30, and performs display control on the display unit 50 corresponding to the indicated position. It comprises a unit 40.

The overall configuration of the information processing apparatus according to this embodiment is as shown in FIG. The operator operates the stylus pen (ultrasonic transmitter) 1 synchronized with the pen holder 34.
Using the input area (Displ used as the display unit 50)
ay Display area of the device). At this time, the ultrasonic receiver 30 calculates the distance between the stylus pen 1 and the ultrasonic sensors (ultrasonic receiving elements) 31a, 31b,... From the transmission / reception timing of the ultrasonic wave transmitted from the stylus pen 1, Computer as arithmetic processing unit 40
Is input to The Computer calculates the two-dimensional or three-dimensional position of the stylus pen 1 in the display area of the display device from the distance value received from the ultrasonic receiving unit 30, and performs a process on the application based on the data.

FIG. 3 shows a specific example of the external structure of the information processing apparatus according to the present embodiment.
The two ultrasonic receiving elements 31a and 31b are disposed in a predetermined positional relationship with respect to the display screen of the CRT display as the first embodiment, and the ultrasonic receiving unit 30 disclosed in FIGS. The unit 40 includes the information processing apparatus main body 1
It is built in 00.

In the vicinity of the display screen of the display unit 50,
A pen holder 34 for accommodating the stylus pen 1 when the stylus pen 1 is not used is provided. Here, the stylus pen 1 is configured as a cordless stylus pen, a driving power source of the stylus pen 1 is a secondary battery built in the stylus pen 1, and the pen holder 34 charges the secondary battery. It also has a function as an adapter for performing.

First, the display unit 5 based on the reception outputs of the two ultrasonic receiving elements 31a and 31b in this embodiment.
The principle of detecting the position indicated by the stylus pen 1 on the display screen 0 will be described.

FIG. 4 shows two ultrasonic receiving elements 31 arranged in a predetermined positional relationship with respect to the display screen of the display unit 50.
3A and 3B show the relationship between the position indicated by the stylus pen 1 and 31b. Now, these two ultrasonic receiving elements 31
Considering the two-dimensional coordinate system XY fixed to a and 31b, the horizontal length of the display screen of the display unit 50 is W.

Here, the ultrasonic receiving element 31a
It is arranged at the origin (0, 0) of the dimensional coordinate system XY,
The ultrasonic receiving element 31b is provided in the two-dimensional coordinate system XY.
It is assumed that it is arranged at a point (0, W) on the axis.

It is assumed that the position indicated by the stylus pen 1 is a point (x, y) on the two-dimensional coordinate system XY, and a distance from the ultrasonic receiving element 31a to the point (x, y). the a, point from the ultrasonic receiving elements 31b (x, y) and the distance to the ^{b, a 2 = x 2 +} y 2 ... (1) b 2 = a ^{(W-x) 2 + y} 2 ... (2) The relationship is established. When x and y are solved from the equations (1) and (2), x = (a ² −b ² + W) / 2W (3) y = ± SQRT [a ² − ｛(a ² −b ² + W ² )] / 2W｝ ² ] (4) where SQRT (A) indicates the square root of A.

Is as follows. Here, since W is a known value, if the distance a from the ultrasonic receiving element 31a to the point (x, y) and the distance b from the ultrasonic receiving element 31b to the point (x, y) are known, 2 is obtained. The position (x, y) indicated by the stylus pen 1 on the two-dimensional coordinate system XY fixed to the ultrasonic receiving elements 31a and 31b can be obtained.

In this embodiment, the position indicated by the stylus pen 1 from the ultrasonic receiving element 31a (x,
The distance a to y) and the distance b from the ultrasonic receiving element 31b to the position (x, y) indicated by the stylus pen 1 are detected using the ultrasonic wave output from the tip of the stylus pen 1.

More specifically, the distances a and b are detected by detecting the time T until the ultrasonic waves output from the tip of the stylus pen 1 are detected by the ultrasonic receiving elements 31a and 31b.
This is performed by detecting a and Tb.

That is, assuming that the spatial transmission speed of the ultrasonic wave output from the tip of the stylus pen 1 is C, the distances a and b can be obtained by detecting the times Ta and Tb as follows: a = C × Ta (5) B) = C × Tb (6)

The processing for detecting the time Ta and Tb until the ultrasonic wave output from the tip of the stylus pen 1 is detected by the ultrasonic receiving elements 31a and 31b is performed by the ultrasonic receiving unit 30 shown in FIG. The processing is performed by the processing unit 32.

FIG. 5 shows a specific configuration of the reception processing section 32 in the ultrasonic receiving section 30 shown in FIG.
In this embodiment, a pen holder 34 for storing the stylus pen 1 when the stylus pen 1 is not used is provided. As will be described in detail later, the pen holder 34 is provided with an ultrasonic transmission unit of the stylus pen 1. A synchronization circuit 35 is provided for synchronizing the output timing of the output ultrasonic wave with the reception processing in the reception processing unit 32.

The synchronizing circuit 35 counts the basic clock output from the basic clock generating circuit 324 provided in the reception processing unit 32, and every time the counted value becomes a constant value, the ultrasonic transmission of the stylus pen 1 is performed. It is configured to output a synchronization signal for controlling the output timing of the ultrasonic wave output from the means.

The stylus pen 1 is provided with a basic clock generating circuit (an oscillator 13 described later) for generating a basic clock having the same frequency as the basic clock generating circuit 324. When the stylus pen 1 is stored in the pen holder 34, a synchronization signal output from the synchronization circuit 35 is input to establish synchronization with the basic clock generation circuit 324 provided in the reception processing unit 32, After the pen 1 is taken out of the pen holder 34, as shown in FIG. 6 (a) output from the basic clock generation circuit that operates in synchronization with the basic clock generation circuit 324 provided in the reception processing unit 32, similarly to the synchronization circuit 35. ) Is counted, and as shown in FIG. 6B, the styler is counted every time the counted value becomes a constant value. It is configured to control the output timing of the ultrasonic waves output from the ultrasonic wave transmission means of the pen 1.

That is, when the stylus pen 1 is stored in the pen holder 34, the output timing of the ultrasonic wave output from the ultrasonic wave transmitting means of the stylus pen 1 and the reception processing unit 3
2 and the output timing of the ultrasonic wave output from the ultrasonic wave transmitting means of the stylus pen 1 coincides with the timing of the synchronization signal applied from the synchronization circuit 35 to the reception processing unit 32. .

The synchronizing signal applied from the synchronizing circuit 35 to the reception processing unit 32 is output from the counters 321 and 3
Counters 321, 32
2 is cleared in synchronization with this synchronization signal.

The basic clock output from the basic clock generating circuit 324 is input to the count input terminals of the counters 321 and 322.
Receiving clocks output from the ultrasonic receiving elements 31a and 31b when an ultrasonic wave output from the tip of the stylus pen 1 is received are input to a control input terminal for controlling the stop of counting of the stylus pen 2.

That is, the counters 321 and 322 are simultaneously reset at the timing when the ultrasonic wave is output from the tip of the stylus pen 1, and the respective ultrasonic receiving elements 31
The basic clock output from the basic clock generation circuit 324 is counted until the reception clock is input from the a and 31b. As a result, the count values of the counters 321 and 322 are determined by the ultrasonic wave output from the tip of the stylus pen 1. Times Ta and Tb until detection by ultrasonic receiving elements 31a and 31b
It corresponds to.

FIG. 7 is a timing chart showing the operation of detecting the times Ta and Tb by the counters 321 and 322. That is, a basic clock generation circuit (not shown) of the stylus pen 1 generates a basic clock shown in FIG. 7A, and generates an ultrasonic wave from the tip of the stylus pen 1 in synchronization with the rise of the synchronization signal shown in FIG. 7B. A transmission clock shown in FIG. 7C for output is generated, and an ultrasonic drive signal shown in FIG. 7D for driving the ultrasonic transmission means of the stylus pen 1 is generated in synchronization with the transmission clock. I do. The stylus pen 1 is driven by this ultrasonic drive signal.
Is transmitted, and the ultrasonic wave is output from the tip of the stylus pen 1 only while the transmission clock is generated.

The ultrasonic waves output from the tip of the stylus pen 1 are received by the ultrasonic receiving elements 31a and 31b.
A reception clock as shown in FIG. 7E is output from the ultrasonic receiving elements 31a and 31b in response to the reception of the ultrasonic waves.

Therefore, the counters 321 and 322 use the rising timing of the synchronizing signal shown in FIG.
The time T up to the rising timing of the reception clock shown in (e), that is, the times Ta and Tb can be obtained by counting the basic clock shown in FIG.

Times Ta and T until the ultrasonic waves output from the tip of the stylus pen 1 counted by the counters 321 and 322 are detected by the ultrasonic receiving elements 31a and 31b.
b is held in the reception time holding circuits 325 and 326, respectively, and is processed by the arithmetic processing unit 40 via the communication unit 33 shown in FIG.
Is transmitted to

The arithmetic processing unit 40 receives the times Ta and Tb transmitted via the communication unit 33, and receives the times Ta and Tb.
The designated position designated on the screen of the display unit 50 by the stylus pen 1 is calculated based on Tb.

In this calculation, first, the distances a and b from the stylus pen 1 to the ultrasonic receiving elements 31a and 31b are calculated based on the above-mentioned equations (5) and (6).
Then, based on the calculated distances a and b and the above equations (3) to (4), the ultrasonic receiving elements 31a and 31
The position (x, y) indicated by the stylus pen 1 on the two-dimensional coordinate system XY fixed to b is calculated. Then, display control on the display unit 50 is performed based on the calculated position (x, y) indicated by the stylus pen 1.

Next, a specific detailed configuration of the stylus pen 1, the ultrasonic receiving unit 30, and the arithmetic processing unit 40 shown in FIG. 1 will be described.

The external structure of the stylus pen 1 used in the apparatus according to this embodiment has, for example, a form as shown in FIG. The stylus pen 1 has an ultrasonic transmission unit inside and has three buttons, a first button 14a, a second button 14b, and a third button 14c. Here, the first button 14a is operated when drawing is performed using the stylus pen 1, for example. The second button 14c and the third button are also associated with various functions that can be executed using the stylus pen 1, such as setting of a display mode in the multi-mode function. Operated when executing a function.

Thus, in the present embodiment, for example, the first button 14a provided on the stylus pen 1
When the operation state of the stylus pen 1 is controlled to the ON state, the stylus pen 1 is given a function as a drawing pen. When the operation state of the second button 14b provided to the stylus pen 1 is controlled to the ON state, It is possible to operate the stylus pen 1 such as giving it a function as an eraser, that is, an eraser.

FIG. 9 shows an internal circuit configuration of the stylus pen 1. As can be seen from the figure, this stylus pen 1 is a transmission timing control unit 1 that controls the transmission timing of ultrasonic waves from the stylus pen 1.
1. An amplifier 15 having an operational amplifier 16 for amplifying the ultrasonic transmitter driving signal output from the transmission timing controller 11, and an ultrasonic transmitter driving signal output from the amplifier 15 having an ultrasonic transmitter 18 And a transmitting unit 17 for transmitting ultrasonic waves.

The transmission timing controller 11 further includes a first button 14a, a second button 14b, and a third button 14b shown in FIG.
A sequencer 12 is provided for controlling the state transition of the ultrasonic transmission timing control from the stylus pen 1 in accordance with the output of the button 14 composed of the button 14c and the basic clock from the oscillator (basic clock generator) 13 for generating the basic clock. Have been.

FIG. 10 shows the ultrasonic receiving unit 30 shown in FIG.
2 shows a specific configuration of the arithmetic processing unit 40.
In the figure, an ultrasonic receiving unit 30 includes a reception processing unit 32,
The communication unit 33 is configured.

Here, the ultrasonic receiving section 30 performs an input process on the ultrasonic receiving output from the receiving sensor section 31 composed of the ultrasonic receiving elements 31a and 31b shown in FIG. The reception processing unit 32 includes an amplifier unit 60, a reception timing control unit 70
The amplifier section 60 is provided with an operational amplifier 61, and the reception timing control section 70 is provided with a counter, a register 71, a sequencer 72, an oscillator 73, and an SCC (serial communication control section) initialization section 74.

Here, the counter and the register 71 are shown in FIG.
The oscillator 73 corresponds to the counters 321 and 322 and the reception time holding circuits 325 and 326 shown in FIG. 5, and generates the basic clock.
Corresponds to 4.

The sequencer 72 includes an oscillator 73
The transition state of the reception timing control of the reception timing control unit 70 is controlled based on the basic clock output from. The sequencer 72 is reset by a synchronization signal (reset signal) from the synchronization circuit 35 of the pen holder 34 shown in FIG.
The transition state of the reception timing control is controlled. The communication unit 33 includes an SCC (serial communication control unit) 3
A 232C driver 332 for driving the RS232C 31 and the RS232C interface is provided.

In FIG. 10, the arithmetic processing unit 40
Is equipped with a predetermined application, has a window processing unit and a mouse driver for controlling display corresponding to the position indicated by the stylus pen 1, and is connected to the communication unit 33 of the ultrasonic receiving unit 30 via the RS232C interface. It consists of a personal computer.

The apparatus according to the present embodiment also supports a multi-pen function that allows simultaneous use of a plurality of stylus pens. Whether or not to select the multi-pen function and the number of stylus pens to be used simultaneously are determined. It can be switched by a dip switch (not shown).

FIG. 11 shows the configuration of this embodiment.
PenNo when the multi-pen function is selected
9 is a timing chart showing ultrasonic wave transmission timing control of the stylus pen of # 0 and the stylus pen of PenNo = # 1.

In this example, the stylus pen with PenNo = # 0 and the stylus pen with PenNo = # 1 each have four ultrasonic transmission timings (shown by $ numbers 1-4, hereinafter referred to as frames # 1- # 4). Are alternately transmitted as a unit.

That is, as shown in FIG.
stylus pen with o = 0, ie, stylus pen Pe
n # 0 transmits ultrasonic waves with four ultrasonic transmission timings as one block. Here, the ultrasonic transmission period at each ultrasonic transmission timing is Tsend, and the ultrasonic transmission interval is Twwait. At the first ultrasonic transmission timing of the four ultrasonic transmission timings, the ultrasonic wave is constantly controlled to follow the cursor displayed on the display unit 50 in accordance with the position of the stylus pen Pen # 0. Is sent. At the second ultrasonic transmission timing, the stylus pen Pen
The ultrasonic wave is transmitted only when the first button 14a is pressed in # 0. At the third ultrasonic transmission timing, the stylus pen Pen # 0 is used for the second button 14b.
Transmits ultrasonic waves only when is pressed. At the fourth ultrasonic transmission timing, the stylus pen P
Ultrasonic waves are transmitted only when the third button 14c is pressed at en # 0.

Similarly, in the stylus pen with PenNo = 1, that is, in the stylus pen Pen # 1, 4
Ultrasonic waves are transmitted with one ultrasonic transmission timing as one block. In other words, in the first ultrasonic transmission timing of the four ultrasonic transmission timings, the ultrasonic wave is constantly controlled to follow the cursor displayed on the display unit 50 in correspondence with the position of the stylus pen Pen # 1. Is sent. At the second ultrasonic transmission timing, the first button 14 is pressed with the stylus pen Pen # 1.
The ultrasonic wave is transmitted only when a is pressed. At the third ultrasonic transmission timing, ultrasonic waves are transmitted only when the second button 14b is pressed with the stylus pen Pen # 1. At the fourth ultrasonic transmission timing, the third button 1 is pressed by the stylus pen Pen # 1.
The ultrasonic wave is transmitted only when 4c is pressed.

The ultrasonic drive signal (ultrasonic drive clock) generated at each ultrasonic transmission timing is, for example, F
Hz signal, and the ultrasonic drive clock is applied to the transmission unit 17 via the amplifier unit 15 shown in FIG.
7 transmits this FHz ultrasonic wave.

In FIG. 11, the ultrasonic transmission timing when the multi-pen function is selected has been described. However, the stylus pen is one of PenNO = 0,
When the multi-pen function is not selected, only the ultrasonic transmission timing control by the stylus pen Pen # 0 shown in FIG. 7 is stored in the pen holder 34 shown in FIG. Is repeated until a synchronization signal is received from the synchronization circuit 35 of FIG. Also, the multi-pen function is selected,
When the number of stylus pens used simultaneously is three or more, each stylus pen sequentially transmits ultrasonic waves with four ultrasonic transmission timings as one unit.

Further, in the above example, the stylus pen Pen
Although the ultrasonic transmission timing in # 0 and Pen # 1 is defined as four times, the number of ultrasonic transmission timings depends on the number of buttons 14 provided on the stylus pens Pen # 0 and Pen # 1, operating conditions, and the like. It can be set as desired. In the above example, the stylus pen Pen # 0,
First button 14a operated at the time of drawing of Pen # 1, for example
When the first button 14a is pressed, an ultrasonic wave indicating that the first button 14a is pressed is generated only at the second ultrasonic transmission timing.
When the button is pressed, an ultrasonic wave indicating that the first button 14a has been pressed may be generated at the second ultrasonic transmission timing and, for example, at the fifth ultrasonic transmission timing. In this case, the detection density (sampling cycle) of the designated position related to the drawing of the first button 14a can be increased, and the designated position can be detected with higher accuracy.

The stylus pen Pen # shown in FIG.
The sequencer 72 in the reception timing control unit 70 of the ultrasonic receiving unit 30 synchronizes the ultrasonic transmission timing on the 0, Pen # 1 side with the ultrasonic transmission timing (the respective frames # 1 to # 4). Receiving elements 31a, 31
The received signal received in step b is processed, and the arithmetic processing unit 40 calculates the positions of the two stylus pens Pen # 0 and Pen # 1 described above, for example.

Here, the frames # 1 to # 4 are synchronized with the ultrasonic transmitting side (stylus pens Pen # 0 and Pen # 1) and the ultrasonic receiving side (ultrasonic reception) as described above. Section 30) has the same meaning. Accordingly, the sequencer 72 of the ultrasonic receiving unit 30 responds to the received signal in the frame # 1 by using the stylus pen Pen.
The ultrasonic receiving element 31a for each of # 0 and Pen # 1,
31b and the frame #
Each of these pens Pen # 0 according to the received signals at # 2 to # 4
And first, second, and third buttons 1 in Pen # 1 and Pen # 1
It is possible to recognize the pressing state of 4a, 14b, 14c. The calculated distance and the recognized button pressing state are transmitted from the reception timing control unit 70 to the arithmetic processing unit 40 through the communication unit 33.

FIG. 12 is a diagram showing an example of the structure of data transmitted from the reception timing control unit 70 to the arithmetic processing unit 40. This data is composed of three bytes, and the first byte (FIG. 3A) shows the pressed state of each button 14 mounted on the stylus pen 1. The second byte [(b) in the figure] is a value indicating the distance from the ultrasonic receiving element 31a in the ultrasonic receiving unit 30 to the stylus pen 1, that is, the distance a in FIG. The third byte [(c) in the figure] is a value indicating the distance from the ultrasonic receiving element 31b in the ultrasonic receiving unit 30 to the stylus pen 1, that is, the distance b in FIG.

The values of the second and third bytes are obtained by converting the basic clock generated by the basic clock generation circuit 324 in FIG.
The numbers counted by the counters 321 and 322 until the ultrasonic waves are transmitted from the stylus pen 1 and received by the ultrasonic receiving elements 31a and 31b, respectively, are shown. Using this count value, the arithmetic processing unit 40
For example, if the basic clock is 1 MHz, one clock time is 1 μsec, and one bit of the second and third bytes is a distance (0.344 m) at which the ultrasonic wave propagates in the air within 1 μsec.
m), each ultrasonic receiving element 31a,
The distance between the stylus pen 1b and the stylus pen 1 is calculated. Furthermore,
Using the calculated distances between the ultrasonic receiving elements 31a and 31b and the stylus pen 1, the coordinates of the stylus pen 1 on the coordinate axes set on the input surface (see FIG. 4) are calculated. This calculation method is as described above.

Incidentally, the calculation accuracy of the position coordinates in the arithmetic processing unit 40 depends on the distance measurement accuracy in the reception timing control unit 70 in the preceding stage. Receive timing control unit 7
In order to perform accurate distance measurement at zero, the ultrasonic receiving element 3
As a countermeasure against this, it is usually necessary to amplify the reception signals from the ultrasonic receiving elements 31a and 31b to a predetermined level by the amplifier unit 60 and receive the signals. A method of inputting to the sequencer 72 of the timing control unit 70 is adopted.

Next, the process of amplifying the received signal in the amplifier section 60 will be described. FIG. 13 shows an amplifier unit 60 in the ultrasonic receiving unit 30 of the device according to the present embodiment.
FIG. 3 shows a detailed circuit diagram of FIG. In the amplifier section 60, the received signals (received analog signals) of the ultrasonic receiving elements 31a and 31b are amplified 100 times by the first-stage operational amplifier 601 and further amplified 100-times by the second operational amplifier 602. . This operational amplifier configuration is generally known as an instrumentation amplifier, and is a circuit used for amplifying a small signal such as a sensor output.

Next, in the amplifier section 60, in the third-stage operational amplifier (comparator) 603 whose threshold voltage is set to 1 V, the reception signal (Vout) amplified by the second-stage operational amplifier 602 and A threshold voltage is compared, and if the value of the received signal is higher than the threshold voltage, a received digital signal corresponding to 5 V is generated, and if the value is lower than the threshold voltage, a received digital signal corresponding to 0 V is generated and output.

In the above amplification process, the ultrasonic receiving element 3
The reception signals (reception analog signals) of 1a and 31b are several mV.
Since the analog signal is very small, it is necessary to pay particular attention to measures against noise in the circuit shown in FIG. This is because normal operation cannot be expected if noise or the like generated by surrounding digital signals enters this circuit.

FIG. 14 shows the received analog signal as 100
FIG. 14 is a diagram illustrating an example of a waveform of a signal amplified twice, that is, a signal 1 in FIG. 13. Thus, even if the received analog signal handled by this device is amplified 100 times,
The leading wave is amplified only to a level of about 200 mV. That is, the leading wave of the received analog signal in this case has a level of only about 2 mV. It is very difficult to amplify such a minute level signal into a digital waveform. However, as shown in FIG. 15, this minute level signal (the leading wave of the received signal) is amplified to about several hundred mV. If it can be done, it is easy to amplify it into a digital waveform as shown in FIG.

However, in the present apparatus, there are many cases where the leading waveform of the received analog signal cannot be amplified due to the amplifying ability of the amplifier unit 60. The reason is,
As described earlier with reference to FIG. 14, the voltage level of the leading wave of the received analog signal is very small, and therefore, the time required for the leading wave to rise and return to the GND level is shorter than that of other waveforms. Because it is extremely small.

According to an experiment performed by the inventor, each waveform level (see FIG. 14) of the received analog signal is increased by approximately twice the magnification for each received waveform. As a result, the waveform following the leading wave can be amplified by the operational amplifier 601 with a probability of 100%, and is not dropped. Also, by the experiment of the inventor, the probability of dropping the leading wave is 1/2.
It is known that it is about 0 or less. This experiment is for the case of using a general-purpose high-precision operational amplifier. The result of this experiment is shown in FIG.
This is an example in which the amplification factor of the first-stage operational amplifier 601 is set to 10 times and the amplification factor of the second-stage operational amplifier 602 is set to 200 times.

As described above, in the present apparatus, the ultrasonic wave transmitted from the stylus pen 1 is sampled in a normal state (a state in which correction processing described later is not performed), and the ultrasonic wave transmitting means and the ultrasonic wave receiving element are sampled. The distance between the stylus pen 1a and the stylus pen 31 is measured using the measured distance.
When the position coordinates are calculated and the position coordinates are transferred to the host software, an incorrect stylus pen position is recognized with a probability of not more than once every 20 times.

As a handwriting input device as shown in FIG.
When an ultrasonic position detection mechanism such as the present device is used, the above-described misrecognition of the stylus pen position causes the D in FIG.
When an input operation is performed on the isplay device using the stylus pen 1, a phenomenon such as a so-called camera shake occurs. For example, when the stylus pen 1 is moved and the cursor is followed, the cursor shakes when the cursor shakes, and when drawing input is performed with the stylus pen 1, a phenomenon occurs in which a drawing line is wavy.

The mechanism of occurrence of these phenomena will be described in more detail with reference to FIGS. In the apparatus according to the present embodiment, two ultrasonic transceivers 1 and 2 (the ultrasonic receiving elements 31) are provided at the upper end of the input surface shown in FIG.
a, 31b), and the stylus pen 1
The ultrasonic transceivers 1 and 2 receive the ultrasonic waves transmitted from the ultrasonic transceivers 1 and 2 and specify the position coordinates of the stylus pen 1. At this time, the X and Y axes are defined as shown in the figure with respect to the input surface, and the coordinates XL and X on the X axis and the Y axis corresponding to the designated position of the stylus pen 1 are determined in the manner described above. Calculate YL.

Next, in FIG. 17, when the ultrasonic receiver 2 measures the distance of the stylus pen 1, if the leading wave can be received correctly, the distance L in the figure can be measured. In the case where is missed, the distance L + a is measured. This distance a is, as described above, one of the ultrasonic waves.
This corresponds to a distance corresponding to the wavelength, for example, 40 which is usually used.
It is 8.6 mm for the KHz ultrasonic wave, and it can be easily predicted that the measurement error becomes a problem in many cases as a handwriting input device.

FIG. 18 shows how the distance between the ultrasonic receiver 1 and the stylus pen 1 is measured. As in the case of the ultrasonic receiver 2 in FIG. 17, a distance measurement error occurs when the leading waveform is missed. Problems occur.

As a result, as shown in FIG. 19, the coordinates where the stylus pen 1 is shown should be originally calculated, but the coordinates of the other three black circles can be calculated. Sex is thought enough. As mentioned above,
When an ultrasonic wave of 40 KHz is used, a in the figure is 8.6 mm, and as a result, a phenomenon occurs in which the cursor trembles at the coordinates of the four corners of a square area having one side of approximately 8.6 mm.

As one method for avoiding the erroneous detection of the stylus pen position that causes the above-mentioned phenomenon such as camera shake,
Each of the ultrasonic receiving elements 31a and 31b from the ultrasonic receiving unit 30
The arithmetic processing unit 40 (which corresponds to PC in FIG. 10) which receives the distance between the stylus pen and the distance between the ultrasonic transmitter and the ultrasonic transmitter performs a correction process using the following equations (7) and (8). It is possible. In this case, a two-dimensional coordinate system is assumed as the coordinate system.

X = (X0 + 3 × X1 + 2 × X2 + 2 × X3 + 2 × X4) ÷ 10 (7) Y = (Y0 + 3 × Y1 + 2 × Y2 + 2 × Y3 + 2 × Y4) ÷ 10 (8) Here, X and Y are upper software. Stylus pen coordinates to pass to. X0 and Y0 are the calculated latest stylus pen coordinate values. Xn and Yn (n = 1 to 4) are stylus pen coordinate values transferred to the host software n times ago.

By performing this correction processing, it is possible to avoid a phenomenon similar to a hand shake of a cursor or the like caused by a reception error of the leading wave in the ultrasonic receiving elements 31a and 31b, and realize a smooth input. This correction method is a simple method of generating stable stylus pen coordinate values by averaging stylus pen coordinate values sampled several times before, but it can be said that the effect is extremely high.

However, according to this correction method, the coordinates of the stylus pen to be passed to the host software are calculated by referring to the sampling coordinate data of the stylus pen up to several times in the past. On the other hand, the reaction (followability) is slowed down, and there is a high tendency to give a great stress to the operator.

In this regard, for example, it is acceptable that the response is somewhat degraded at the time of drawing. The reason is that it is generally accepted that an operator performs an input by slowly moving the stylus pen 1 in order to perform a smooth input. Therefore, by recognizing the drawing operation and performing heavy correction processing based on the above equations (7) and (8), it is possible to avoid obstacles such as wavy drawing lines.

As described above, in the present embodiment, three buttons (see FIG. 8) are mounted on the stylus pen 1, and the stylus pen 1 has a functional configuration that is depressed when the first button 14a draws. In the ultrasonic transmission sequence composed of frames # 1 to # 4 in FIG. 11, ultrasonic waves are always transmitted in frame # 1 and frames # 2 to # 4 are the first to third buttons (14a to 14c) of the stylus pen 1. Ultrasonic waves are transmitted only when is pressed. Therefore, if the ultrasonic wave is transmitted and received in the frame # 2 between the ultrasonic transmitting side and the ultrasonic receiving side synchronized with each other, it can be recognized that the drawing operation has been performed.

However, even if a certain degree of response reduction can be tolerated at the time of drawing, there has been no improvement in drawing with good response. From this viewpoint, a phenomenon similar to the above-described camera shake can be always achieved without lowering the response. It is desired to realize a correction method for avoiding this.

[0097] In addition, there are many operation examples in which the poor operation of the cursor with respect to the movement of the stylus pen 1 (response) adversely affects the operation thereof. For example, during a presentation, when the presenter points to a place to be explained using the stylus pen 1, if the response of the cursor is poor, the explanation cannot be performed smoothly.

Therefore, in the ultrasonic position detecting mechanism according to the present embodiment, the measured distance data is stored as described below, and the current measured data is stored every time the distance data is measured. Compared to past measurement data
When these differences correspond to one wavelength of the ultrasonic wave, the current measurement data is replaced with the past measurement data, and the stylus pen position coordinates are always calculated using the accurate measurement data at the time of the normal reception of the first wave. This prevents erroneous recognition of the stylus pen position coordinates when the leading wave of the ultrasonic wave is missed, and maintains a good response.

Hereinafter, an outline of the correction processing based on the first correction method of the present invention will be described with reference to FIG. FIG.
In order to make the explanation easy to understand, a measurement distance correction method between ultrasonic transmitters / receivers on one-dimensional coordinates is shown.

Now, as a target of the correction processing based on the first correction method, time 1n to 3n, 7n, 8 in FIG.
It is assumed that the distance between the ultrasonic transmitters / receivers has been measured as the distance L at n and 10n and the distance L + a at times 4n to 6n and 9n. Here, the measurement of the distance between the ultrasonic transmitters / receivers is sequentially performed from time 1n to 10n, and the distance a in FIG.
Is one wavelength of the ultrasonic wave to be used.

At this time, the measured distance at the time 4n is different from the past measured data (in this example, the distance data L at the time 3n) by a distance a, that is, the measured distance is one wavelength of the ultrasonic wave to be used. Since a corresponding difference is recognized, the measurement distance at the time 4n is discarded, and the stylus pen 1 is used using the past measurement data (distance data L at the time 3n).
Is calculated. Further, at this time, the measurement data between the ultrasonic transmitter / receiver at the time 4n is stored as the distance L which is a corrected value.

Next, at time 5n, since the past measurement data which has already been stored is L and the current measurement data is L + a, the measurement distance at this time 5n is discarded, and The position of the stylus pen 1 is calculated using the measurement data (L stored as the measurement data for the time 4n). The measurement data at this time 5n is stored as L.

Such processing is repeated. At time 10n, since the stored past measurement data is L and the current measurement data is L, the stylus pen 1 is used by using the measurement distance at time 10n as it is. Is detected. The measurement data at this time 10n is naturally L
Is stored.

In the apparatus according to the embodiment of the present invention (see FIG. 1), the above-described correction processing is performed in the arithmetic section 42 of the arithmetic processing section 40. FIG. 21 is a block diagram showing a detailed functional configuration of the operation unit 42. The data acquisition unit 421, the operation execution unit 422, and the reception timing monitoring unit 42
3, a history data storage unit 424, a comparison unit 425, and a data replacement unit 426. In the device illustrated in FIG. 10, the calculation unit 42 corresponds to a PC.

A more detailed operation of the correction processing in the arithmetic section 42 will be described with reference to a flowchart shown in FIG. In the arithmetic processing unit 42, when the process of receiving the distance data between the ultrasonic transmitter / receiver input from the reception processing unit 32 through the communication unit 33 is started (step 220), first, the reception timing monitoring unit 423 0 is substituted for a variable n indicating whether it is the second reception timing (step 221), and the distance data is acquired by the data acquisition unit 421 (step 222).

Next, the reception timing monitoring section 423 determines whether or not the number of reception timings n is 0 (step 223). If n = 0 (step 223Ye)
s) The current measurement data is stored in the history data storage unit 424 as past measurement data (step 227).
At this time, the calculation execution unit 422 calculates the coordinate value of the stylus pen 1 using the stored current measurement data (step 226).

On the other hand, if n = 0 is not satisfied (NO in step 223), the past measurement data already stored in the history data storage unit 424 and the current measurement data acquired by the data acquisition unit 421 in step 222 are used. Are compared by the comparing unit 425 (step 224), and it is determined whether or not the difference between the past measurement data and the current measurement data matches the distance of one wavelength of the ultrasonic wave used in the present apparatus. In the present embodiment, it is assumed that an ultrasonic wave of 40 KHz is used, and the distance difference between the current measurement data and the current measurement data described above with reference to a length of 8.6 mm for one wavelength of the ultrasonic wave is used as a reference value. It is determined whether or not the value matches the reference value (step 225).

Here, when the difference between the present measurement data and the past measurement data does not match the length of one wavelength (step 225 NO), the data replacement unit 426 supplies the current measurement data to the calculation execution unit 422. The calculation execution unit 422 calculates the coordinate value of the stylus pen 1 using the current measurement data (step 226).

On the other hand, when the difference between the present measurement data and the past measurement data coincides with the length for one wavelength (YES in step 225), data replacement section 426 stores the current measurement data in history data storage section 424. The measured data is replaced with the past measurement data and supplied to the calculation execution unit 422, and the replaced past measurement data is stored in the history data storage unit 424 as the current measurement data (step 22).
8). Further, at this time, the arithmetic execution unit 422 regards the past measurement data replaced by the data replacement unit 426 as the current measurement data, and calculates the coordinate value of the stylus pen 1 using the measurement data (step 226). .

By repeatedly performing the above processing for the number of reception timings n, the correction processing as shown in FIG. 20 can be realized. Although only the correction processing between a pair of ultrasonic transmitters / receivers is disclosed in the flowchart in FIG. 22, the correction processing is actually performed by the number of mounted ultrasonic receivers. In a PC illustrated in FIG. 10 as an example of an actual device, the above-described correction process
This will be executed by the C mouse driver or application.

Next, a second correction method according to the present invention will be described. In the measurement distance correction processing between the one-dimensional ultrasonic transmitter / receiver based on the first correction method described above (see FIG. 20), when the distance measured at time 1n is obtained by dropping the leading wave of the ultrasonic wave. According to the principle of “when the difference between the current measurement data and the past measurement data corresponds to one wavelength of the ultrasonic wave, the current measurement data is replaced with the past measurement data” in this correction processing, the measurement data of time 1n is obtained. As a result of the replacement processing of the measured value that is followed, as shown in FIG. 23, after the time 1n, a distance of an erroneous value longer than the actual measured distance by one waveform length of the ultrasonic wave is calculated at all reception timings. Will be done. According to the measurement distance correction result shown in the figure, the original distance L is calculated as the position coordinate value of the stylus pen 1 as the distance L + a, although the distance between the ultrasonic transmitter and the receiver is originally L. Will be. In this case, the movement of the cursor does not occur, but the position indicated by the stylus pen 1 and the position of the cursor are shifted.

According to the result of the experiment conducted by the inventor, the probability of dropping the leading wave is about 1/20, which is very low in frequency. Therefore, in the measurement of the distance between the ultrasonic transmitters and the receivers, it is apparent that the case where the accurate distance L is measured as shown in FIG.

From this viewpoint, in the second correction method of the present invention, when a difference of one wavelength of the ultrasonic wave occurs twice consecutively in the comparison between the past measurement data and the present measurement data, The inconvenience is solved by storing current measurement data as past measurement data and using the current data for detecting the position of the stylus pen 1.

FIG. 24 shows an example of the measurement distance correction result based on the second correction method. As shown in the drawing, in the correction result based on the second correction method, this ultrasonic transmission is performed from time 2n to time 3n with respect to the measurement distance L + a when the leading wave of the ultrasonic wave is missed at time 1n. As the distance between the receivers becomes the distance L + a two consecutive times, the distance is corrected to the distance a which is the second measurement data.

In this case, the distance between the ultrasonic transmitters / receivers fluctuates from time 2n to time 3n, and at this moment, the cursor shakes, etc., but after that, an accurate value is measured. It is possible. Since the instantaneous movement of the cursor falls within an instant, there is no problem in actual operation. The reason is that it has been found that at least 40 points of input per second are required in order to realize sufficient cursor tracking and smooth drawing input in detecting the position coordinates of the stylus pen 1. The time required for one point is at most 1/40 second or 25mse
This is because it can be said that the human eye cannot perceive the instantaneous vibration.

FIG. 25 is a block diagram showing a functional configuration of an operation unit 42 for realizing the second correction method of the present invention. The operation unit 42 corresponding to the first correction method shown in FIG.
In the functional configuration of (1), the comparison result of the comparison unit 425 is monitored, and the comparison result that the difference between the past measurement data and the present measurement data is equal to one wavelength of the ultrasonic wave is continuously N (N is a natural number). If the number of times has been obtained, the process further includes a replacement canceling unit 427 that prohibits the process of replacing the current measurement data with the past measurement data and gives the current measurement data to the calculation execution unit 422 as it is.

Hereinafter, a more detailed operation of the correction process based on the second correction method will be described with reference to a flowchart shown in FIG. Note that, in the flowchart in the figure, the number N of consecutive comparison results indicating a difference for one wavelength (hereinafter, referred to as the number of consecutive comparison results) N is represented as m.
In the case of (m = 1), that is, when the replacement of the current measurement data with the past measurement data occurs continuously, the above replacement is prohibited and the process returns to the process using the current measurement data as it is. An example is shown.

In the arithmetic processing section 42, the reception processing section 32
Of processing for receiving distance data between ultrasonic transmitters / receivers input from communication unit 33 through communication unit 33 (step 260)
Accordingly, first, the reception timing monitoring unit 423 and the replacement canceling unit 427 substitute 0 for both a variable n indicating the number of reception timings and a variable m indicating the number of consecutive comparison results (step 261). The distance data is acquired by the acquisition unit 421 (step 262).

Next, the reception timing monitoring section 423 determines whether or not the number of reception timings n is 0 (step 263), and if n = 0 (step 263Ye).
s) The current measurement data is stored as past measurement data in the history data storage unit 424 (step 268).
At this time, the arithmetic execution unit 422 calculates the coordinate value of the stylus pen 1 using the stored current measurement data (step 267).

On the other hand, if n = 0 (step 263 NO), the past measurement data already stored in the history data storage unit 424 and the current measurement data acquired by the data acquisition unit 421 in step 262 are used. Are compared by the comparing unit 425 (step 264), and it is determined whether or not these differences match the distance for one wavelength of the ultrasonic wave used in the present apparatus. In the present embodiment, it is assumed that an ultrasonic wave of 40 KHz is used, and the distance difference between the current measurement data and the current measurement data described above with reference to a length of 8.6 mm for one wavelength of the ultrasonic wave is used as a reference value. It is determined whether or not the value matches the reference value (step 265).

If the difference between the current measurement data and the past measurement data does not match the length of one wavelength (step 265 NO), the data replacement unit 426 replaces the current measurement data with the past measurement data. And supply it to the calculation execution unit 422 without any change. At this time, the replacement canceling unit 427
Is the number of continuous comparison results m
Is maintained at (m = 0) (step 266), and the calculation execution unit 422 calculates the coordinate value of the stylus pen 1 using the current measurement data provided from the data replacement unit 426 (step 267).

On the other hand, if the difference between the current measurement data and the past measurement data matches the length of one wavelength (step 265 YES), the replacement canceling unit 427 determines that the number m of consecutive comparison results at the time is It is determined whether a preset value m = 1 (step 269). here,
If not m = 1 (step 269 NO), the data replacement unit 426 stores the current measurement data in the history data storage unit 424
The measured data is replaced with the past measurement data and supplied to the calculation execution unit 422, and the replaced past measurement data is stored in the history data storage unit 424 as the current measurement data (step 270). At that time, the replacement canceling unit 42
No. 7 adds 1 to the continuous number m of comparison results due to the occurrence of the above-mentioned replacement to make (m = 1) (step 27).
1) On the other hand, the operation execution unit 422 regards the past measurement data replaced by the data replacement unit 426 as the current measurement data, and uses the measurement data to use the stylus pen 1.
Is calculated (step 267).

In the above processing, when the comparison result that the difference between the present measurement data and the past measurement data corresponds to one wavelength of the ultrasonic wave is continuously obtained, the replacement canceling unit 427 determines in step 269 by the replacement canceling unit 427. = 1 (Yes in step 269). In this case, the replacement canceling unit 427 transmits the determination result to the data replacing unit 426, and the data replacing unit 426 notifies the data canceling unit 427 that "a difference of one ultrasonic wave has occurred continuously". Based on the determination result, the current measurement data is not replaced with the past measurement data, and the current data is stored in the history data storage unit 424 as the past data (step 268). At this time, the arithmetic execution unit 422 calculates the coordinate value of the stylus pen 1 using the stored current measurement data (step 267).

With the above-described processing, the correction processing as shown in FIG. 24 can be realized. In this case, even if the distance measured at time 1n is the time when the leading wave of the ultrasonic wave was missed, the actual processing is performed thereafter. A situation in which the distance measurement longer than the measurement distance of the ultrasonic wave by one waveform length continues can be reliably prohibited after performing the above-described replacement processing N times, and the position indicated by the stylus pen 1 and the position of the cursor are matched. It becomes possible.

Next, consider a case where the stylus pen 1 has really moved by one wavelength of the ultrasonic wave. The operator moves the stylus pen 1 for one wavelength of the ultrasonic wave (for example, when the frequency of the ultrasonic wave is 40 KHz, it corresponds to about 8.6 mm).
Moving is considered very infrequent in practice, but is possible in practice. In this case, if the above-described correction method (see FIGS. 20 and 24) is applied, the coordinates where the stylus pen 1 has moved will be ignored. However, the present invention can cope with such a situation without any problem as described below.
Here, the above-mentioned coping method will be examined by distinguishing between a case where the stylus pen 1 really moves by one wavelength of the ultrasonic wave and then continues to move and a case where the stylus pen 1 stops.

In the case where the stylus pen 1 keeps moving In FIG. 27, it is assumed that the distance between the ultrasonic transmitter / receiver is measured as L at time 1n. In addition, time 2
At n, it is assumed that the distance between the ultrasonic transceivers is measured as L + a. The first measurement of the present invention
By using the correction method described above, the distance between the ultrasonic transmitters and the receivers at the time 2n is corrected to L (see FIGS. 7A and 7B).

Next, at time 3n, since the stylus pen 1 is moving, the distance between the ultrasonic transmitter / receiver is L.
It takes a value other than + a. Therefore, the distance value at time 3n is L + b (a and b are not equal) as shown in FIGS. 27A and 27B, and the position coordinates of the stylus pen 1 are determined based on this value. calculate. At this time, time 2n
In this case, the cursor is momentarily displayed in a place different from the movement of the stylus pen 1, but as described above, this time is at most 25 msec, and does not pose a problem to human eyes.

When the stylus pen 1 is stationary In FIG. 28, it is assumed that the distance between the ultrasonic transmitter / receiver is measured as L at time 1n. Further, it is assumed that the distance between the ultrasonic transmitter / receiver is measured as L + a at time 2n. By using the first correction method of the present invention with respect to this measurement result, the distance between the ultrasonic transmitter / receivers at time 2n is corrected to L as shown in FIG.

Next, at time 3n, since the stylus pen 1 is stationary, the distance between the ultrasonic transmitter / receiver is L.
Take the value of + a. At this time, by applying the second correction method of the present invention, the distance value between the ultrasonic transmitter / receiver at the time 3n is corrected to L + a. At this time, time 2n
In this case, the cursor momentarily points to a place different from the actual stylus pen position, but there is no operational problem for the reasons already described.

In the above embodiment, a rear projector display is assumed as the display unit 50 in FIG. 4, but the pen input device of the present invention is not limited to an information processing device using the rear projector display.
For example, the present invention can be similarly applied to an information processing apparatus using a front projector display as the display unit 50 as shown in FIG.

In addition to the information processing apparatus using the large-sized display, the pen input device of the present invention can be configured as shown in FIG.
The present invention can be similarly applied to an information processing apparatus using a desktop computer having a CRT display as shown in FIG. 1 or a notebook computer having an LCD display as shown in FIG.

In the above embodiment, the configuration for detecting the position of the stylus pen 1 two-dimensionally has been described. However, the present invention can also detect the position of the stylus pen 3 three-dimensionally. Further, in the above embodiment, the RS232C interface is used as a communication interface between the ultrasonic receiving unit 30 and the arithmetic processing unit 40 (PC). However, in the present invention, a communication interface other than the RS232C interface is similarly used. It goes without saying that it can be applied.

[0133]

As described above, according to the present invention,
An arithmetic processing unit that receives a measurement distance between the ultrasonic transmitter / receiver from the ultrasonic reception unit compares the past measurement data with the current measurement data, and a difference between the two is equal to one wavelength of the ultrasonic wave used in the apparatus. If the current position is equal to the current position, the current measurement data is replaced with the past measurement data, and the pointing position of the input pen is always calculated using the accurate measurement data when the first wave is normally received. In the case of a mistake, a stable pointing position can be input without a shake phenomenon with the input pen. In this case, if at least one distance data measured immediately before is held as past measurement data, it is not necessary to hold a sampling value from several times before. Good response can be maintained.

Also, in the present invention, if the state in which the difference between the past measurement data and the current measurement data is equivalent to one wavelength of the ultrasonic wave continues continuously N times, the current measurement data is replaced with the past measurement data. Since the replacement of the measurement data is stopped and the pointing position of the input pen is calculated using the current measurement data, the first distance data erroneously detected due to the reception error of the leading wave is used as a reference value for all subsequent distances. It is possible to prevent a situation in which the measurement distance at the reception timing is continuously corrected following the erroneous reference value, and that an erroneous distance measurement between the ultrasonic transmitter / receiver cannot be continuously performed N times. A highly reliable correction function according to the actual situation can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an information processing apparatus to which a pen input device according to the present invention is applied.

FIG. 2 is a diagram showing a schematic configuration of the entire information processing apparatus shown in FIG. 1;

FIG. 3 is an exemplary perspective view showing an example of the external structure of the information processing apparatus shown in FIG. 1;

4 is a diagram showing a relationship between two ultrasonic receiving elements arranged in a predetermined positional relationship with respect to a display screen of a display unit shown in FIG. 1 and a position designated by a stylus pen.

FIG. 5 is a block diagram showing a functional configuration of a reception processing unit of the ultrasonic receiving unit shown in FIG.

FIG. 6 is a flowchart showing a relationship between a basic clock and an ultrasonic wave transmission timing in the stylus pen shown in FIG. 5;

FIG. 7 is a timing chart showing an operation of detecting an ultrasonic reception time by the counter shown in FIG. 5;

8 is an external configuration diagram of a stylus pen used in the information processing apparatus shown in FIG.

FIG. 9 is a block diagram showing an internal circuit configuration of a stylus pen used in the information processing apparatus shown in FIG. 1;

FIG. 10 is a block diagram illustrating a functional configuration of an ultrasonic receiving unit and an arithmetic processing unit illustrated in FIG. 1;

11 is a timing chart showing ultrasonic transmission timing control of a stylus pen with PenNO = 0 and a stylus pen with PenNO = 1 when the multi-pen function is selected in the information processing apparatus shown in FIG. 1;

FIG. 12 is a diagram illustrating an example of a data format of output data from the reception timing control unit illustrated in FIG. 10;

FIG. 13 is a diagram illustrating an example of a circuit configuration of an amplifier unit in the reception processing unit illustrated in FIG. 10;

FIG. 14 is a diagram showing an example of a received ultrasonic amplification waveform by a first-stage operational amplifier of the amplifier unit shown in FIG. 13;

FIG. 15 is a diagram showing an example of a desirable received ultrasonic amplification waveform by a first-stage operational amplifier of the amplifier section shown in FIG. 13;

FIG. 16 is a diagram showing a relationship between an input surface and input coordinates in the information processing apparatus shown in FIG. 1;

FIG. 17 shows an ultrasonic transmission / reception on the input surface shown in FIG. 16;
The figure which shows an aspect of the distance measurement mistake between receivers.

FIG. 18 shows an ultrasonic transmission / reception on the input surface shown in FIG.
The figure which shows another aspect of the distance measurement mistake between receivers.

FIG. 19 is a diagram illustrating a state of a displacement of the pointing position of the input pen when the calculated distance in the mode illustrated in FIGS. 17 and 18 is used.

FIG. 20 shows an ultrasonic transmission / reception based on the first correction method of the present invention.
The conceptual diagram which shows an example of the measurement distance correction between receivers.

FIG. 21 is a block diagram showing a functional configuration of an arithmetic unit for realizing the correction processing shown in FIG. 20 in the arithmetic processing unit of the information processing apparatus shown in FIG. 1;

FIG. 22 is a flowchart showing a correction processing operation by the calculation unit shown in FIG. 21;

FIG. 23 shows an ultrasonic transmission / reception based on the correction processing shown in FIG.
The conceptual diagram which shows an example of the measurement distance correction mistake between receivers.

FIG. 24 is a conceptual diagram showing an example of a measurement distance correction process between an ultrasonic transmitter and a receiver based on the second correction method of the present invention for eliminating the correction error shown in FIG. 23.

FIG. 25 is a block diagram showing a functional configuration of an arithmetic unit for implementing the correction processing shown in FIG. 24 in the arithmetic processing unit of the information processing apparatus shown in FIG. 1;

FIG. 26 is a flowchart showing a correction processing operation by the calculation unit shown in FIG. 25;

FIG. 27 is a conceptual diagram showing an application example of the correction processing shown in FIG. 20 when the stylus pen is actually moved by one wavelength of the ultrasonic wave.

FIG. 28 is a conceptual diagram showing an application example of the correction processing shown in FIG. 24 when the stylus pen is actually moved by one wavelength of the ultrasonic wave.

FIG. 29 is a diagram showing another embodiment of the present invention using a front projector display as a display unit.

FIG. 30 is a diagram showing still another embodiment of the present invention using a desktop computer having a CRT display as a display unit.

FIG. 31 is a diagram showing another embodiment of the present invention using a notebook computer having an LCD display as a display unit.

[Explanation of symbols]

1 stylus pen, 11 transmission timing control unit, 1
2 ... sequencer, 13 ... oscillator, 14 ... button, 1
5: Amplifier section, 16: Operational amplifier, 17: Sending section, 18
... Ultrasonic wave transmitter, 30 ... Ultrasonic wave receiving unit, 31 ... Reception sensor unit, 31a, 31b, 31c ... Ultrasonic wave receiving element, 32
... Reception processing unit, 60 ... Amplifier unit, 61 ... Op amp, 7
0: reception timing control unit, 71: counter, register, 72: sequencer, 73: oscillator, 74: SC
C (serial communication control unit) initialization unit, 321, 322 ...
Counter, 324... Basic clock generation circuit, 325, 3
26: reception time holding circuit, 33: communication unit, 331: SC
C (serial communication control unit), 332: 232C driver, 34: pen holder, 35: synchronous circuit, 40: arithmetic processing unit, 41: communication unit, 42: arithmetic unit, 421: data acquisition unit, 422: arithmetic execution unit 423: reception timing monitoring unit 424: history data storage unit 425: comparison unit
26: Data replacement unit, 427: Replacement cancellation unit, 43: Judgment unit, 44: Display control unit, 50: Display unit

Claims (4)

[Claims] 1. An apparatus for transmitting an ultrasonic wave from an ultrasonic transmitting unit mounted on an input pen and receiving the ultrasonic wave by an ultrasonic receiving unit based on a time between the ultrasonic transmitting unit and the ultrasonic receiving unit. Distance measuring means for measuring the distance of the input pen, and calculating means for calculating two-dimensional or three-dimensional position coordinates of the input pen using the measured distance, based on the position coordinates calculated by the calculating means. In a pen input device for inputting a position indicated by the input pen in a predetermined input area, a measurement distance storage means for storing a measurement distance between the ultrasonic transmission means and the ultrasonic reception means in the past, and a measurement distance storage means Comparison means for comparing the past measurement distance and the current measurement distance stored in the, the difference between the past measurement distance and the current measurement distance to one wavelength of the ultrasonic wave A pen input device comprising: a correction unit that abandons the current measurement distance when the distances are equal and gives the past measurement distance to the calculation unit. 2. A comparison result of the comparison means is monitored, and a comparison result that a difference between a past measurement distance and a current measurement distance is equal to one wavelength of the ultrasonic wave is continuously N (N is a natural number). 2. The pen input device according to claim 1, further comprising: a correction canceling unit that abandons the past measurement distance when the number of times has been obtained and gives the current measurement distance to the calculation unit. 3. The time between the ultrasonic transmitting means and the ultrasonic receiving means based on the time at which the ultrasonic wave is transmitted from the ultrasonic transmitting means mounted on the input pen and the time at which the ultrasonic wave is received by the ultrasonic receiving means. A pen input device that measures the distance of the input pen, calculates two-dimensional or three-dimensional position coordinates of the input pen using the measured distance, and inputs a position indicated by the input pen in a predetermined input area. While storing the measured distance between the ultrasonic transmitting means and the ultrasonic receiving means, comparing the stored past measured distance and the current measured distance, the past measured distance and the current measured distance When the difference from the current distance is equal to one wavelength of the ultrasonic wave, the current measurement distance is abandoned, and the position coordinates are calculated using the past measurement distance. Position coordinate correction method that. 4. If the comparison result that the difference between the past measurement distance and the current measurement distance is equal to one wavelength of the ultrasonic wave is obtained continuously N times (N is a natural number), 4. The position coordinate correction method in the pen input device according to claim 3, wherein the use of the measurement distance is stopped, and the position coordinates are calculated using the current measurement distance.