JP2002132436A - Coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and highly precise coordinate input device. SOLUTION: Ultrasonic propagation time detected by using the envelope and the zero crossing point of ultrasonic waves received with two ultrasonic wave receivers produces a certain level of error, but the phase difference of ultrasonic waves that the two ultrasonic wave receivers receive produces a very small error. Accordingly, the phase difference of ultrasonic waves received by the two ultrasonic wave receivers is used for detecting a coordinate. More specifically, the phase difference between the two ultrasonic waves received is the time corresponding to the difference M (=L2-L1) between respective distances L1, L2 of the ultrasonic wave transmitter and the two receivers. Consequently, the inputted coordinate of an input device is computed, by triangulation, from the first distance L1 obtained using the envelope or the like, and the difference M between the distances obtained from the phase difference between the received waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for detecting a position of an input device using ultrasonic waves and inputting coordinates, and more particularly, to a compact fixed unit having a plurality of ultrasonic receivers. The present invention relates to a coordinate input device capable of improving the accuracy of position detection. The coordinate input device of the present invention includes a pen type or a mouse type for inputting a trajectory of a handwritten character or the like and inputting coordinates of an input surface.

[0002]

2. Description of the Related Art A coordinate input device using ultrasonic waves has been proposed as a device for inputting the trajectory and coordinates of an input device to a computer. A coordinate input device using an ultrasonic wave receives, for example, an ultrasonic wave from an ultrasonic transmitter provided in an input device by a plurality of ultrasonic receivers provided at predetermined positions with respect to an input surface. Then, the distances L1 and L2 between the input device and the ultrasonic receiver are obtained from the products of the respective ultrasonic propagation times and the ultrasonic velocities, and the coordinates of the input device are obtained by triangulation. When the input surface is provided at an arbitrary position in the three-dimensional coordinate space, the position of the input device can be detected by providing at least three ultrasonic receivers. Since such a coordinate input device uses an ultrasonic wave, it is not necessary to use a tablet having a special structure as an input surface, and the input surface is not limited and is highly convenient.

In order to determine the distance between the input device and the ultrasonic receiver with high accuracy, it is desirable to shorten the wavelength of the ultrasonic wave as much as possible. However, if the wavelength of the ultrasonic wave is short,
The attenuation rate of the ultrasonic wave accompanying propagation in the air increases, and it becomes difficult to input coordinates from a wide range of input surfaces. Also, the attenuation of the ultrasonic wave causes a decrease in the accuracy of the detected distance. Therefore, the ultrasonic wavelength of the coordinate input device that is currently widely used is a certain long wavelength, for example, a frequency of about 40 KHz,
It has a wavelength of about 8 mm. With this degree, the attenuation is not so large, and a region that can be used practically can be used as the input surface.

The above propagation time is obtained from the time from the synchronization timing using infrared rays or the like to the reception timing of the ultrasonic wave, and the sound speed is multiplied to obtain the distances L1 and L2 between the input device and the receiver.

As shown in FIG. 1, when an ultrasonic transmitter emits an ultrasonic wave by vibrating its membrane by a driving pulse, the ultrasonic wave has a waveform whose amplitude gradually increases. Therefore, in order to detect the reception timing of the ultrasonic wave, the timing at which the envelope of the ultrasonic wave exceeds the predetermined threshold values rt1 and rt2 on the receiving side is generally used. That is, the envelope of each received ultrasonic wave is determined from the synchronization signal such as infrared rays by the threshold values rt1 and rt.
Times T1 and T2 until the time exceeds 2 are detected as propagation times. However, since the envelope has a small slope and a gradually increasing waveform, the timing exceeding a certain threshold is
It may be shifted back and forth due to noise, and includes some error.

Therefore, as shown in FIG. 2, it has been proposed to use the timing of the zero-cross point after the received ultrasonic wave exceeds the reference value rt3 as a method for eliminating the above error. At the zero-cross point of the ultrasonic wave, the above-described error can be eliminated because the slope of the amplitude is steeper than the envelope. However, even when the zero-cross point is used, the difference between the timing at which the received wave 1 exceeds the reference value tr3 and the timing at which the received wave 1b exceeds the reference value tr3 in FIG. In the above example, a displacement of 8 mm) occurs.

Hitherto, as means for solving the problem of the wavelength shift, it has been proposed to monitor the timing continuously and replace it with the previous timing when the timing greatly changes. For example, JP-A-10-149251.
However, such a method requires continuous monitoring of a plurality of received ultrasonic waves, and cannot be used when coordinates are input sporadically.

As described above, the distances L1 and L2 between the ultrasonic transmitter of the input device and the ultrasonic receiver of the fixed unit.
There is a certain limit to obtaining with high accuracy. Therefore, the conventionally proposed coordinate input device increases the distance between the plurality of ultrasonic receivers to some extent, maintains the accuracy of the triangulation method, and increases the total coordinate detection accuracy.

[0009]

However, in the case of a relatively large input surface such as a blackboard, there is no problem even if the distance of the ultrasonic receiver is increased to some extent, but a relatively small area which can be secured beside the computer. An ultrasonic receiver with such a large separation distance cannot be used on the input surface or desk surface of the system. In a mobile environment using a notebook computer or a portable information terminal, it is desired to reduce the distance between the ultrasonic receivers.

However, when the distance between the ultrasonic receivers is reduced, the coordinate detection accuracy of the triangulation method is reduced, and this is coupled with the decrease in the measurement accuracy of the distance between the input device having the ultrasonic transmitter and the ultrasonic receiver. However, the accuracy of the total coordinate detection is not improved, which is an obstacle to the practical use of the small coordinate input device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coordinate input device in which the distance between ultrasonic receivers is made as small as possible and which is compact, and which has high coordinate detection accuracy.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, one aspect of the present invention is to provide an ultrasonic wave propagating apparatus utilizing an ultrasonic envelope received by two ultrasonic receivers and a zero-cross point. Although some error occurs when time is detected, 2
The phase difference between the ultrasonic waves received by the two ultrasonic receivers has very little error. Therefore, the phase difference between the ultrasonic waves received by the two ultrasonic receivers is used for coordinate detection. That is, the phase difference between the two received ultrasonic waves is a time corresponding to the difference M (= L2−L1) between the respective distances L1 and L2 between the ultrasonic transmitter and the two receivers. Therefore, the difference M between the first distance L1 obtained by using an envelope or the like and the distance obtained from the phase difference of the received wave.
Then, the input coordinates of the input device are calculated by the triangulation method.

When the distance between the ultrasonic receivers is large to some extent, the distance L1 and the distance difference M may be obtained with a certain resolution. However, when the distance between the ultrasonic receivers is small, the resolution of the distance L1 is not so large. It is not necessary to increase the distance difference M
It is necessary to increase the resolution of That is, as the distance between the receivers becomes smaller, the change in the distance difference between the two input points also becomes smaller, and a higher resolution is required accordingly. Therefore, the above-described necessary condition can be satisfied by obtaining the distance difference M from the phase difference of the received wave, which can be expected to have high accuracy.

In a preferred embodiment of the present invention, the first distance L1 is obtained by using the envelope of the received ultrasonic wave, and the distance difference M = L2-L1 is obtained by using the phase difference of the zero cross point of the received wave.
Is obtained, and the input coordinates are obtained from these values by triangulation.

In the preferred embodiment of the present invention, when the phase difference at the zero-cross point of the received wave is used, if the distance of the receiver increases, the distance difference (phase difference × sound velocity) obtained from the phase difference and the actual distance difference Causes an error of an integral multiple of the wavelength.
In this case, the area of the input surface is limited to a narrow area where no error occurs, or two distances L obtained from the envelope are used.
1, L2, the distance difference M obtained from the phase difference
Is corrected to an integral multiple of the wavelength.

According to another aspect of the present invention, there is provided a coordinate input device for inputting coordinates from an input surface to a computer, the input device having an ultrasonic transmitter and being movable to a desired position in the input surface. A fixed unit attached to a predetermined position with respect to an input surface and having at least first and second ultrasonic receivers for receiving ultrasonic waves from an ultrasonic transmitter of the input device; A first ultrasonic propagation time between the ultrasonic transmitter and the first ultrasonic receiver is generated from the ultrasonic wave received by the receiver, and the first and second ultrasonic receivers receive the ultrasonic wave. And a receiving unit that generates a phase difference between the ultrasonic waves, wherein the position of the input device is obtained according to the first ultrasonic wave propagation time and the phase difference.

Still another aspect of the present invention is an ultrasonic mouse that realizes the same operability as a mechanical mouse as a coordinate input device using ultrasonic waves. The ultrasonic mouse of the present invention
A pressure-sensitive switch is provided at the bottom of the main body to detect a pressure when the operator is touching the main body on a horizontal surface. Only when the pressure-sensitive switch is detecting pressure, the synchronization infrared ray and the ultrasonic transmitter are driven at predetermined time intervals. By adopting such a configuration, input of coordinates when the mouse is in the air is prevented, driving of the infrared or ultrasonic transmitter when the operator is not operating is prohibited, and power consumption can be suppressed. The relative distance when the mouse is moved on the horizontal plane can be reflected on the cursor on the screen of the computer.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

FIG. 3 is a diagram illustrating the principle of triangulation in the present embodiment. In the figure, the coordinates T where the input device is located and the positions of the two ultrasonic receivers R1 and R2 separated by the distance p are shown with respect to the two-dimensional coordinates xy on the input surface. The distance from the input device to the first receiver R1 is L
1, if the distance to the second receiver is L2, the distance L2
Is L1 + M (M is a distance difference). Therefore, if the distance L1 and the distance difference M = L2-L1 are obtained from the propagation time and the phase difference of the ultrasonic wave, the input coordinates T are obtained according to the principle of the triangulation method shown in FIG.

That is, by solving the following equation x ² + y ² = L1 ² (x−p) ² + y ² = (L1 + M) ² for x and y, x = (p ² −2 L1M−M ² ) / 2 py = a (L1 ² -x ^{2) 1/2,} input coordinates T (x, y) can be obtained.

FIG. 4 is a diagram showing the locus of the distance difference M.
The locus of the difference M between the distance between the input point T and the two receivers R1 and R2 is a hyperbola 50 uniquely determined from the position of the receivers R1 and R2 and the distance difference M. Therefore, two distances L1, L
If one of the two is determined, the position of the input point T is determined. In this case, the required resolution of the distances L1 and L2 is determined by the receiver R
It is understood that the resolution of the distance difference M needs to be smaller as the distance p between the receivers becomes smaller, though it does not depend on the distance p between R1 and R2.

That is, when the distance p between the receivers is small, what is actually required to be obtained with high accuracy is the distance difference M = L1−L2. For example, when determining the position of the input device at a resolution of 0.1 mm at the position of x = p / 2 mm and y = 300 mm,
At 200mm, distance L1 is 0.1mm resolution and distance difference M is 0.063mm
What is necessary is just to obtain by resolution. On the other hand, when the distance p between the receivers is 15 mm, the distance L1 may be kept at 0.1 mm resolution, but the distance difference M must be obtained at 0.005 mm.

Therefore, in the present embodiment, the distance L1 that does not require high accuracy is determined by an envelope waveform of an ultrasonic wave that does not cause a wavelength error unlike the case of using zero cross, and the distance difference M1 that requires high accuracy is obtained.
Is obtained from the phase difference of the received wave itself.

FIG. 5 is a diagram showing a method for obtaining a propagation time and a phase difference from two received waves. The time T1 from the synchronization signal using infrared rays or the like to the timing when the envelope of the reception wave SA1 of the first receiver R1 exceeds the threshold rt1 is equal to the time T1 from the input device having the ultrasonic transmitter to the first receiver. Detected as ultrasonic propagation time. By using the envelope, it is possible to avoid occurrence of an error corresponding to the wavelength described in FIG. That is, although the propagation time T1 includes some error, it is possible to avoid the occurrence of a large error of the wavelength λ (for example, 8 mm) accompanying the use of the zero cross point.

On the other hand, the envelope of the first received wave SA1 is equal to the threshold rt1.
Is detected as the phase difference between the two received waves, the timing difference T3 between the zero-cross point Z1 after exceeding the threshold value and the zero-cross point Z2 of the second received wave SA2 immediately after the zero-cross point Z1. Here, the zero-cross point is a point where the phase of the received wave is 0 °. of course,
It is also possible to set the point at a phase of 180 ° as the zero cross point. You only need to unify them.

In the example shown in FIG. 5, when the propagation time T2 is obtained at a timing when the envelope of the second received wave SA2 exceeds the threshold value rt2, the deviation from T1 + T3 using the phase difference T3 is as shown. Occurs. However, the phase difference T3 obtained by comparing the zero-cross points of the received wave having a steep rise is
Accuracy is higher than that obtained by using an envelope.

When obtaining the distance difference M using the phase difference,
The following issues need to be considered: When the second reception wave SA2 shown in FIG. 5 advances, the zero cross point of the second reception wave SA2 corresponding to the zero cross point Z1 of the first reception wave SA1 is Z
2, Z3, Z4. . . Will be one of Therefore, between the distance difference m obtained by the phase difference T3 due to the zero cross point Z2 immediately after the zero cross point Z1 and the actual distance difference M,
The relationship of M = m + nλ (−λ / 2 <m <λ / 2) holds. That is, there is an ambiguity (error) of an integral multiple of the wavelength λ between the distance difference m obtained from the phase difference and the actual distance difference M.

As shown in FIG. 4, the distance difference M is the distance p between at most two receivers R1 and R2. Therefore, 2
If the distance p between the two receivers is within a half wavelength λ / 2, there is no error of the integral multiple of the wavelength λ. As the distance p between the two receivers increases, the distance difference M (−p <M <
p) has an error that is an integral multiple of the wavelength λ. It is understood that the number of possible integers n increases as the distance p increases.

Therefore, in the present embodiment, the distance difference L1 obtained by using the highly accurate unnecessary distances L1 and L2 obtained from the envelope.
The above ambiguity is eliminated by obtaining the approximate position of the correct zero-cross point according to -L2 = M.

FIG. 6 is a diagram for explaining the occurrence of ambiguity in the distance difference m obtained from the phase difference. In the case of the inter-receiver distance p ≦ λ / 2 shown in FIG. 6A, the distance difference M ≦ ± λ / 2 regardless of the position of the input point Ta. No ambiguity occurs. In the figure, it is assumed that only one of the 180 ° regions for the receivers R1 and R2 is considered.

The distance between the receivers λ / 2 <p ≦ in FIG.
In the case of λ, M ≤ ± λ, so n = ± 1 in addition to n = 0
The case occurs. For example, when p = λ, as shown in Fig. 6 (b), the range of ± 30 ° between the straight line −λ / 2 and λ / 2 is the case of n = 0, and If n = 1 on the left,
The right side of −λ / 2 is the case where n = −1. Therefore, the distance difference m obtained from the phase difference T3 may be the position of Ta or the position of Tb, and it cannot be distinguished which is correct. However, since the positions Ta and Tb are far apart, it is possible to distinguish between Ta and Tb based on the distance difference obtained from the distances L1 and L2 with large errors. FIGS. 6 (c) and 6 (d)
This is an example in which the distance p is further large. As the distance p increases, the number of possible points increases.

In the case shown by a solid line in FIG.
The line dividing ± 2,… is explained. As shown in FIG. 4, when the receivers R1 and R2 are apart from each other by a distance p, the locus of the difference M between the distances L1 and L2 from both receivers is 4 (x−p / 2) ² / M ² + 4 y ² / (M−p) ² = 1. The hyperbola R1 and R2 of the middle point forms a through y-axis the angle theta is θ = 90 - arctan {(p / M) 2 - 1} is asymptotic to ^1/2 of a straight line. Therefore, by substituting the distances p and M into this equation, a line dividing the multiple n is obtained.

For example, p = λ / 2, λ, 3λ / 2, 2λ, 5
In the case of λ / 2 and 3λ, they are separated by the angle lines in the table below.

[0034]

[Table 1]

As shown in the above table, the distance between the receivers p =
At λ / 2, the line of M = ± λ / 2 becomes ± 90 °, and Fig. 6 (a)
As shown in the figure, the whole range (± 90 °) is obtained when n = 0. When p = λ, the line for M = ± λ / 2 is ± 30 °, and the line for M = ± λ is ± 90 °, as shown in FIG. 6 (b). When p = 3λ / 2,
The lines dividing n are ± 19.5 °, ± 41.8 °, ± 90 °, and as shown in FIG. 6C, Ta (n = 0), Tb (n = 1), and Tc (n = −
It becomes ambiguity of 1).

As described above, as the inter-receiver distance p increases, the number of areas to be divided increases, so that the accuracy of the distance difference L2−L1 obtained from the approximate distances L1 and L2 for distinguishing them is necessary. Since the accuracy of the position obtained from the envelope increases as the distance p increases, the problem is not so significant.

As described above, when the distance p between the receivers is limited to λ / 2 or less, ambiguity of an integral multiple of the wavelength λ does not occur. Thus, by limiting the position of the two receivers in that way, the ambiguity can be avoided. Alternatively, be separated receiver distance p is lambda / 2 or more, the range of the input surface to be used, within the scope of the above formula θ, θ <90 -arctan {( p / M) 2 - 1} 1 / If it is ² , ambiguity of an integral multiple of the wavelength λ does not occur.
For example, even if p = λ, the range of use of the input surface is −30 °
If it can be limited to <θ <30 °, it is limited to n = 0, so no ambiguity occurs.

FIG. 7 is a diagram showing a coordinate input device according to the first embodiment. A display 52 is connected to the computer 51, and a coordinate input device including a pen-type input device 4 having an ultrasonic transmitter and a receiving unit 54 provided with an ultrasonic receiver is connected to the computer 51. The receiving unit 54 is an input surface 53 such as paper.
The coordinates of the input device 4 are detected, and the drawing drawn on the input eye 53 is given to the computer and displayed.

FIGS. 8 and 9 show another example of use of the coordinate input device. In FIG. 8, the receiving unit 54 is attached to the upper left corner of the personal computer display screen 55. In this case, the coordinate system of the receiving unit 54 and the display screen 55
If the relationship of the coordinate system is set in advance, it becomes possible to input coordinates with the input pen 4. When a character or a figure is drawn on the screen 55 with the input pen 4, it is displayed on the screen 55. By doing so, it becomes possible to input coordinates more easily than in the conventional method in which a special sheet is placed on a CRT or LCD screen. Further, the receiving unit 54 may be fixed to the screen 55 or fixed to paper as necessary.

In FIG. 9, the receiving unit 56 is connected to the input pen 4
The handwriting of the input pen can be stored in the memory of the microcontroller in the receiving unit 56. In this way, the user carries the input pen 4 with the cap, removes the cap 56 from the input pen as necessary, fixes the cap 56 to the input paper 53, writes with the input pen 4, and writes the handwriting at that time. Just save it in the cap, return to the office, and transfer the handwriting to your computer. Infrared LED for synchronization for data transfer at this time
It is preferable to be able to carry out in.

FIG. 10 is a configuration diagram of a pen-type input device. As shown in FIG. 10A, the pen-type input device 4 is provided with an ultrasonic transmitter 17 made of a cylindrical piezoelectric film made of polyvinylidene fluoride.
A 40 kHz ultrasonic pulse is transmitted. With the cylindrical shape, the ultrasonic waves can be transmitted in the same manner even when the input pen 4 rotates. In addition, an infrared LED 18 for generating infrared light is provided on the head of the pen to synchronize with the receiving unit. The pen point is provided with a ball-point pen core 16 for writing on an input surface such as paper like a normal ball-point pen. When writing is performed, the ball-point pen core 16 is pushed upward and the contact detection switch 19 is turned on.

As shown in FIG. 10B, the drive circuit 20 includes a timer 23, an ultrasonic drive circuit 25, and an LED drive circuit 24. Is detected, the timer 23
Generates the trigger signal S23 at a constant period,
5, 24 cause the infrared LED 18 and the ultrasonic transmitter 17 to generate an infrared pulse and an ultrasonic pulse, respectively. This cycle is set to, for example, about 100 Hz, since it is sufficient if the movement of the pen can be detected stably.

FIG. 11 is a configuration diagram of the receiving unit.
The receiving unit 54 includes two ultrasonic receivers R1 and R2.
Are provided close to each other, for example, at a distance of 15 mm, and the receivers detect the ultrasonic pulse from the input pen 4. Also,
The receiving unit is provided with an infrared light receiving element PD that detects infrared light that is a synchronization pulse. Receiving unit 54
A clip-shaped paper scissors 57 is provided at the bottom of the receiver, and the receiving unit is fixed to paper or the like on the input surface. Further, the receiving unit 54 has a built-in receiving unit 58 that detects the received infrared rays and ultrasonic waves and detects the propagation time and the phase difference. The receiving unit 54 is provided with two receivers close to each other, so that the receiving unit 54 is configured to be compact as a whole.

FIG. 12 is a configuration diagram of the coordinate input control unit. A receiving unit 58 incorporated in the receiving unit 54 detects the propagation times T1 and T2 of the ultrasonic wave and the phase difference T3 and supplies them to a coordinate input control unit 60 in the computer. The input coordinate calculation unit 62 in the coordinate input control unit 60 calculates a distance L1 from the input pen to the first receiver R1 from the propagation time T1, and a distance L1 from the phase difference T3 and a distance L2 from the phase difference T3 to the second receiver R2.
Is obtained, and an input coordinate value is further obtained by a triangulation method. The obtained coordinate values are given to the display control unit 63 and reflected on the display on the display unit 52.

The coordinate input control unit 60 further has an input surface setting unit 61. For example, when the receiving unit 54 is fixed to the input surface, the input surface setting unit 61 sets a conversion formula between the two-dimensional coordinates of the receiver of the receiving unit and the two-dimensional coordinates of the input surface. Initial values such as the distance p and the area of the input surface are also set. The set initial data is stored in the memory 64.

The coordinate input control unit 60 is, for example, a program installed in a computer as a driver of a coordinate input device. Alternatively, the coordinate input control unit 60 may be built in the receiving unit.

FIG. 13 is a block diagram of the receiving unit in the receiving unit. Referring to the ultrasonic wave shown in FIG.
The operation of the receiving unit will be described. When the contact detection switch 19 detects that the ball-point pen core is pressed, the input pen 4 sends out an infrared pulse and an ultrasonic pulse at a constant cycle. On the receiving unit side, when the infrared light receiving element PD detects the infrared synchronization pulse, the timers 70a and 70b start operating in response to the detection signal S65.

At the same time, when the transmitted ultrasonic waves SA1, SA2 are received by the ultrasonic receivers R1, R2, the input amplifiers 66a, 66
b, and the envelope detection circuits 67a and 67b generate the envelopes of the respective received waves. As shown in FIG. 5, at the timing when the envelope of the ultrasonic reception wave SA1 exceeds the threshold value rt1, the computer 68a detects the reception of the ultrasonic wave and stops the timer 70a. As a result, the timer 70a can measure the airborne ultrasonic propagation time T1 from the input pen 4 to the receiver R1. Similarly, the propagation time T2 to the receiver R2 is measured by the timer 79b.

Further, the time difference between the received waves SA1 and SA2
T3 is detected when the zero-cross comparators 69a and 69b detect the respective zero-cross points Z1 and Z2. That is, when the comparator 68a detects that the envelope of the first received wave SA1 has exceeded the threshold, the zero-cross comparator 69a detects the timing of the next zero-cross point Z1 in response thereto. At this timing, the timer 70c starts measuring. Next, in response to the detection of the zero-cross point Z1 by the zero-cross comparator 69a, the second zero-cross comparator 69b detects the zero-cross point Z2 of the second received wave SA2 immediately after that, and stops the measurement by the timer 70c. As a result, the timer 70c can measure the phase difference T3 shown in FIG. The timer 70c is masked by the output of the comparator 68a so as not to operate until the ultrasonic wave arrives.

The times T1, T2, T3 detected as described above
Accordingly, the input coordinate calculation unit 62 in the coordinate input control device 60 calculates the coordinates (x, y) of the input pen.

FIG. 14 is an operation flowchart of the input coordinate calculation unit in the coordinate input control device. First, the input coordinate calculation unit 62 takes in the propagation times T1 and T2 and the phase difference T3 (S11), and adds the sound speed V to the propagation times T1 and T2 (about 364 m / s2 at 20 ° C.).
And the approximate distances L1, L between the input pen 4 and the receivers R1, R2
2 is obtained (S12). Next, the approximate distance difference M0 (= L2−L1) is obtained from the difference between the approximate distances L1 and L2 (S13). After that, the distance difference m1 (= T3 × V) is calculated from the highly accurate phase difference T3, and the error nλ for the wavelength is corrected by comparing with the approximate distance difference M0 to obtain the accurate distance difference M (S14). Then, based on the approximate distance L1 and the high-precision distance difference M, the above-described triangulation equation is solved to determine the coordinates (x0, y0) of the input pen (S15).

The input coordinates (x0, y0) may include an error depending on the position. The reason is the first
In addition, since the ultrasonic wave is attenuated as the distance increases, the amplitude of the entire envelope detected when the propagation distance is long decreases. Therefore, if the reception timing is detected with a certain threshold, the position where the envelope exceeds the threshold shifts backward as the distance from the input pen to the receiver increases, and the detected reception timing is delayed, and the actual distance Distances L1 and L2 farther than are detected. As a result, calculated input coordinates (x0, y0)
Is farther than it really is.

Second, since the ultrasonic receiver has directivity, the amplitude of the received wave decreases as the input pen moves away from the front having the highest directivity. So, similarly,
The calculated input coordinates (x0, y0) are farther than they actually are, as the position of the input pen is shifted sideways with respect to the receiver.

Since these errors are almost constant once the coordinate input device is determined, the errors can be measured in advance and the detected input coordinates can be corrected. FIG. 15 is a diagram showing a measurement result of the error. FIG. 15A shows the error depending on the distance for each different angle, and FIG. 15B shows the error depending on the angle for each different distance. As shown in FIG. 15A, the error occurs at a distance of 50 mm or more, and increases in a substantially proportional relationship as the distance increases. From these measurement results, it can be seen that the error e is approximated by a third-order polynomial with respect to the angle θ and a straight line with respect to the distance L1. Therefore, the approximate expression of the error is as follows.

[0055] ^{e = (a3θ 3 + a2θ 2} + a1θ + a0) (L1-L0)
+ (b3θ ³ + b2θ ² + b1θ + b0) where L0 = 50mm,

[0056]

[Table 2]

Is as follows.

Therefore, as shown in step S16 of the flowchart, it is preferable to correct the distance L1 from the error e and recalculate the correct coordinates (x1, y1). The correction method is not limited to the calculation according to the error equation as described above. An appropriate error correction table is created in advance, recorded in the memory 64 of FIG. 12, and the table is referred to. Correction may be performed.

Further, in FIG.
Is bent and fixed to the paper 53 as the input surface,
The coordinates (x1, y1) detected by the receiving unit 54 are rotated with respect to the coordinates (X, Y) on the input paper 53. Therefore, when the receiving unit 54 is fixed to the input paper 53,
It is necessary to calibrate the rotation angle amount α as an initial value and perform coordinate conversion at the time of coordinate calculation. The setting of the initial value is shown in FIG.
Is performed by the input surface setting unit 61.

FIG. 16 is a diagram showing such coordinate conversion. The two-dimensional coordinates XY of the input surface shifted by a certain angle α with a certain distance from the two-dimensional coordinates xy of the receiving unit 54 are shown. In the calibration of the above initial values, a position A to be used as a reference on the paper and a horizontal position B (a position at the same X coordinate) are designated by the input pen 4. When the coordinates (xa, ya) and (xb, yb) of the two positions A and B at the receiving unit 54 and the input surface setting unit 61 at the receiving unit are obtained, the rotation angle α is α = arctan ((yb− ya) / (xb−xa)).

Therefore, the coordinates (x1, y1) obtained by the receiving unit 54 are converted into coordinates (X, Y) on the input paper 53 by the following conversion formula (S17 in FIG. 14).

X = (x1−xa) × cosα + (y1−ya) × sinα Y = − (x1−xa) × sinα + (y1−ya) × cosα By the above processing, the coordinates of the input pen on the input paper surface ( X,
Y) is obtained and displayed on the display unit 52 via the display control unit 63.

In the above embodiment, the input pen 4 is provided with an infrared LED. However, the receiving unit 54 is provided with an infrared light emitting element LED, the input pen 4 is provided with an infrared light receiving element PD, and the input pen receives infrared light. It is also possible to transmit an ultrasonic wave upon reception.

In the above embodiment, the receiving unit 54 may be provided with two ultrasonic transmitters, and the input pen 4 may be provided with one ultrasonic receiver. In this case, the two ultrasonic waves may be alternately transmitted so that they are not simultaneously transmitted. First, the distance L1 between the first transmitter and the input pen is measured, and then the second transmitter and the input pen are measured. Measure the distance L2 from the pen,
The phase difference may be obtained by subtracting the transmission interval difference from the time from the phase at the first transmission to the phase at the second transmission. Also,
If the timer overflows at a specific time and the remainder can be calculated, setting the transmission interval to the overflow time of the timer eliminates the need for long-term measurement or subtraction, thereby simplifying the configuration.

FIG. 17 shows a modification of the receiving section in the receiving unit. FIG. 18 is a timing chart illustrating the operation of the receiving unit in FIG. The receiving unit of FIG. 17 is the same as that of FIG. 13 except that timers 70d and 70e are added as compared with the receiving unit of FIG.

According to the experiments performed by the inventors, when the distance between the input pen and the receiving unit is short, the relationship between the amplitude and the distance of the received ultrasonic wave becomes complicated, and is proportional to the distance shown in FIG. Correction may not be possible. For example, distance 5
If the distance is 0 mm or less, it is difficult to correct the error accurately. Therefore, FIG. 15A does not show an error smaller than 0 mm.

Therefore, as a modified example of the method of detecting the distance, in this example, when the distance is shorter than the predetermined reference value Lth, the envelope of the received ultrasonic waves SA1 and SA2 is changed as shown in FIG. Time T4 of zero crossings Z1, Z2 after exceeding thresholds rt1, rt2
Then, distances L1 and L2 are calculated from T5. When the distance is limited to the reference value Lth or less, the amplitude of the ultrasonic wave is stably large.
An error of one wavelength does not occur due to the relationship between the envelope and the threshold values rt1 and rt2. Therefore, the first propagation time T4 is obtained from the first zero cross position Z1 exceeding the threshold value rt1, and the second propagation time T5 is obtained from the first zero cross position Z2 exceeding the threshold value rt2.

In order to obtain the time T4, in the receiving unit 58 shown in FIG.
The measurement is started by the start signal from the reception of R, the comparator 68a masks the stop signal of the zero-cross comparator 69a until the envelope exceeds the threshold rt1, and the timer 70d responds to the detection of the subsequent zero-cross point Z1 to start the measurement. finish. In a similar manner, the timer 70e measures the second propagation time T5 from the other received ultrasonic wave SA2.

FIG. 19 is a flowchart of the coordinate input operation unit in a modification of FIGS. If the distance L1 is equal to or longer than the reference value Lth, the process goes to step S13 as in the case of FIG.
Through steps S16 to S16, the position (x0, y0) is obtained from the approximate distance L1 and the highly accurate distance difference M, and the position (x1, y1) is obtained by position correction. When the distance L1 is less than the reference value Lth, the input pen is located near the receiving unit, and as described with reference to FIG. 18, the position (x1, y1) is directly obtained from the times T4 and T5 to correct the position. Is not performed. In any case, the position (x1, y1) obtained from the receiving unit is coordinate-transformed to obtain the coordinates (X, Y) of the input surface.

The phase difference T3 is usually detected by one received ultrasonic wave. However, if the phase differences T3 of a plurality of ultrasonic waves are obtained and averaged, the accuracy of the phase difference T3 is further improved. For this purpose, for example, the timer 70c in FIG. 17 is constituted by a counter for counting a specific clock, and the operation of the counter is not terminated by one received ultrasonic wave, but the counting of the ultrasonic power of 2 q is continued. Then, if the lower q bits of the counter are ignored, the average value of 2 ^q times can be easily calculated. By configuring the timer 70c with a counter, it is possible to easily obtain the average value of the coefficient a plurality of times, and to obtain the highly accurate phase difference T3.

As described above, the two-dimensional coordinate values in the input plane are
Even a receiving unit in which two ultrasonic receivers are brought close to each other can be obtained with high accuracy. By utilizing this principle, it is possible to detect the position of the input device in a three-dimensional space using a compact receiving unit.

FIG. 20 is a diagram showing an example applied to a three-dimensional mouse. In the example of FIG. 20, a receiving unit 76 that receives an ultrasonic wave from the three-dimensional mouse 75 is provided on the display 52 for a three-dimensional mouse 75 having an ultrasonic oscillator 77 and an infrared LED.

FIG. 21 is a diagram showing a receiving unit for a three-dimensional mouse. The receiving unit 76 has a photodiode PD that receives infrared rays, and three ultrasonic receivers R1, R2, and R3 that are provided close to each other. Inside, a receiving unit is provided similarly to the two-dimensional example, and the timing at which each of the ultrasonic receivers R1, R2, and R3 receives an ultrasonic wave and the phase difference are detected from the infrared synchronization signal. Further, a coordinate input control unit for obtaining three-dimensional coordinates according to the propagation time and time difference detected by the receiving unit is built in the receiving unit 76 or installed in a computer.

FIG. 22 is a diagram showing an example of a receiving section in the case of a three-dimensional mouse. To use a three-dimensional mouse,
It is necessary to detect the three-dimensional coordinates of the mouse. In this example, similarly to the case where the two-dimensional coordinates are obtained from the approximate distance L1 and the high-precision phase difference M described above, the ultrasonic wave SA1 received by the receiver R1 is used.
The propagation time T11 is obtained by the timer 70a from the envelope of the above, and then the approximate distance L1 is obtained. Further, the phase difference T14 between the ultrasonic waves SA1 and SA2 is obtained by the timer 70ab. When obtaining the phase difference T14, the ambiguity of the wavelength is removed by using the approximate distance obtained from the propagation time T12 of the ultrasonic wave SA2. Further, the phase difference T15 between the ultrasonic waves SA1 and SA3 is obtained by the timer 70bc. The ambiguity of the wavelength at this time also depends on the propagation time T of the ultrasonic SA3.
13 removed. From the phase differences T14 and T15, distance differences M1 and M2 are obtained by multiplying the sound speeds, respectively.

Then, from the approximate distance L1 and the distance differences M1 and M2,
The three-dimensional coordinates (x, y, z) of the input device are obtained as follows. In this case, the distances between the receivers R1, R2 and R1, R3 are both p.

X ² + y ² + z ² = L 1 ² (x−p) ² + y ² + z ² = (L 1 + M 1) ² x ² + (y−p) ² + z ² = (L 1 + M 2) ² If y and z are solved, x = (p ² −2 L1 M1 −M1 ² ) / 2 py = (p ² −2 L1 M2 −M2 ² ) / 2 pz = (L1 ² −x ² −y ² ) ^{1 /} It becomes ² .

The receiving unit shown in FIG. 22 has three ultrasonic waves SA1, SA2,
Three sets of input amplifiers, half-wave rectifier circuits, comparators, and zero-cross comparators for detecting SA3 are provided.
1, T12, T13 and phase differences T14, T15 are obtained. And
The above-described calculation is performed by the coordinate input control unit 60 to calculate three-dimensional coordinates.

As described in the example of the two-dimensional coordinates, when the distance to the input device is small, it is difficult to perform the correction according to the distance.
It is preferable that three-dimensional coordinates be obtained by obtaining 2, L3. When the distance to the input device is large, the three-dimensional coordinates are obtained by the above method. Then, correction is made according to the distance and the angle.

[Second Embodiment] The input device using ultrasonic waves has been described. Among the input devices that use ultrasonic waves, the ultrasonic mouse does not require a special contact surface on the desk unlike a conventional mechanical mouse, and there is no danger of dust accumulating on the ball that contacts the contact surface. Is excellent. However, in a mouse using an ultrasonic wave, as described above, coordinates are input to a computer using the coordinate positions in the input surface, so that a relatively wide input surface is required. In addition, a mouse that uses ultrasonic waves can transmit ultrasonic waves even when the mouse is in the air, providing the operability of moving the cursor in the computer screen according to the relative distance on the desk like a mechanical mouse. Can not do.

As a second problem of the ultrasonic mouse, there is a problem of power consumption. The ultrasonic mouse transmits infrared rays as a synchronization signal without connecting to a computer, and transmits ultrasonic waves for position detection. Therefore, if the ultrasonic mouse always transmits the synchronization signal and the ultrasonic wave, the power consumption in the mouse increases, and the power of the built-in battery is lost.

Therefore, in the mouse using ultrasonic waves according to the second embodiment, it is detected that the mouse is placed on the desk and the operator is in contact with the mouse, and only during that time the infrared synchronization is performed. A signal and an ultrasonic wave are transmitted at a constant cycle.

FIG. 23 is a block diagram of such an ultrasonic mouse. An ultrasonic mouse 80 has an input click button 82 at the top of a main body 81, and an infrared LED at the front of the main body 81.
83, and an ultrasonic transmitter 84, and a driving circuit 8 therein.
5 and a battery 86. Also, at the bottom of the main body 81,
A pressure-sensitive switch 87 is provided for detecting the weight of the mouse when placed on a flat surface such as a desk and the weight when the mouse touches the operator. The pressure-sensitive switch 87 detects the state when the mouse is placed on a flat surface and the operator touches the mouse, and supplies a detection signal to the drive circuit.

FIG. 24 is an internal configuration diagram of an ultrasonic mouse according to the second embodiment. The signals from the right button 82R and the left button 82L of the click button are supplied to the LED drive circuit 89 in the drive circuit, and in response, infrared rays modulated so that the right and left buttons can be detected are transmitted from the infrared LED 83. . When detecting the above-mentioned state, the pressure-sensitive switch 87 gives a detection signal to the timer 88. In response, the timer 88 outputs a trigger signal with a fixed period to the LED.
The signals are supplied to the driving circuit 89 and the ultrasonic driving circuit 90, and the infrared synchronization signal and the ultrasonic wave are transmitted to the receiving unit. The infrared synchronization signal is also a signal modulated so as to be distinguishable from the button signal.

FIG. 25 is a configuration diagram of a receiving section according to the second embodiment. The configuration of the receiving unit shown in FIG.
A demodulation circuit 91 is added to the receiver shown in FIG. 3 so that left and right button inputs can be distinguished from ultrasonic synchronization signals.

FIG. 26 is a view for explaining the coordinate detection of the ultrasonic mouse. In this example, the ultrasonic receivers R1 and R2 are provided at the upper left end of the display unit 93 of the notebook personal computer 92, and the infrared light receiving element PD is provided at the center thereof. Infrared mouse, which is an input device, is located on the desk P (Xm, Ym)
It is located in. Infrared mouse, ultrasonic receiver R1, R2
Is always located in the plane of z = H of the three-dimensional coordinates (x, y, z).

Therefore, the coordinates (Xm, Y
m) is the distance L between the two ultrasonic receivers R1 and R2.
If 1, L2 can be measured, it can be calculated. In the ultrasonic mouse according to the present embodiment, the infrared LED and the ultrasonic transmitter are driven only when the operator operates the desk with the pressure-sensitive switch. Can be detected.

FIG. 27 is a flow chart of the cursor position detection in the second embodiment. The ultrasonic mouse according to the present embodiment transmits an infrared synchronization signal and an ultrasonic wave at a constant cycle only when the ultrasonic mouse is placed on a desk and touched by an operator. Then, it is necessary to control the movement of the cursor on the computer screen according to the moving distance of the mouse moving on the desk surface.

Therefore, in the flowchart of FIG. 27, an operation is performed to obtain the new cursor position by adding the moving distance of the mouse on the desk to the current position of the cursor. Furthermore,
In order to detect that it is the moving distance of the mouse on the desk, it is also determined whether or not the front and rear detection positions have been detected corresponding to the cycle time of the timer built in the mouse.

As shown in FIG. 27, first, the initial position (Xm, Ym) of the mouse and the initial position (Xc, Yc) of the cursor are registered (S31). When the mouse's pressure-sensitive switch detects the state of operation on the desk, it receives an infrared synchronization signal and an ultrasonic wave, and receives a new position (Xm ', Y
m ') is detected (S32). Whether or not the new mouse position corresponds to a certain period of time of the mouse timer is checked based on whether or not it is within a specified time from the previous mouse position input (S33). If it is within the specified time, it is considered that the position of the mouse has been changed as a result of operating on the desk, and the registered cursor position (Xc, Yc)
Is changed by the relative movement distance of the mouse (Xm′−Xm, Ym′−Ym) (S34). Then, the mouse position (Xm ', Y
m ') is replaced with the new current position (Xm, Ym) (S3
Five). If the input of the new position of the mouse is not within the specified time from the previous input, it is considered that the movement of the mouse is not being performed on the desk, and only the position of the mouse is updated (S35). ).

By performing such control, even if the mouse is returned to its original position on the desk in the air, the position of the cursor in the computer does not change. The relative distance when moved with is reflected in the conversion of the cursor position in the computer. Such operability is the same as that of a conventional mechanical mouse. The pressure-sensitive switch detects that the mouse has been placed on a horizontal surface, such as a desk, by the pressure-sensitive switch, and only when this happens, the infrared LED or ultrasonic transmitter is driven, thus reducing power consumption. Can be.

Further, the ultrasonic mouse according to the second embodiment is provided with an ultrasonic receiver on the mouse side, receives ultrasonic waves from two ultrasonic transmitters, and obtains a distance between the two. Is also good.

The above embodiments can be summarized as follows.

(Supplementary Note 1) A coordinate input device for inputting coordinates from an input surface to a computer, comprising: an input device having an ultrasonic transmitter and movable to a desired position in the input surface; Is attached to the specified place,
A fixed unit having at least first and second ultrasonic receivers for receiving ultrasonic waves from an ultrasonic transmitter of the input device; and transmitting the ultrasonic waves from the ultrasonic waves received by the first ultrasonic receiver. A receiving unit that generates a first ultrasonic propagation time between the first ultrasonic receiver and the first ultrasonic receiver, and generates a phase difference between the ultrasonic waves received by the first and second ultrasonic receivers; And a position of the input device is obtained according to the first ultrasonic wave propagation time and the phase difference.

(Supplementary Note 2) In the supplementary note 1, the receiving unit generates the first ultrasonic wave propagation time at a timing when an envelope of the received ultrasonic wave exceeds a predetermined threshold. apparatus.

(Supplementary note 3) In Supplementary note 1 or 2, the receiving unit obtains the phase difference based on a timing difference between zero-cross points of ultrasonic waves received by the first and second ultrasonic receivers. Coordinate input device.

(Supplementary note 4) The coordinate input device according to supplementary note 1, wherein a distance between the first and second ultrasonic receivers is set to be equal to or less than a half wavelength of the ultrasonic wave.

(Supplementary note 5) In Supplementary note 1, in the case of the distance p between the first and second ultrasonic receivers,
An angle θ (= θ <90−arctan [(2p / λ) ² −1｝ ^1/2 , where λ is the ultrasonic wavelength) is determined from a line perpendicular to the midpoint of the straight line connecting the two ultrasonic receivers. A coordinate input device provided within a range.

(Supplementary note 6) In Supplementary note 1, the time difference between the second ultrasonic wave propagation time between the ultrasonic wave transmitter and the second ultrasonic wave receiver and the first ultrasonic wave propagation time may be calculated. Therefore, an error of an integral multiple of the ultrasonic wavelength is added to the phase difference.

(Supplementary Note 7) In the supplementary note 1, the first and second ultrasonic receivers are connected according to a first distance obtained from the first ultrasonic propagation time and the ultrasonic velocity. The coordinate input device according to claim 1, wherein the first distance obtained from the first ultrasonic wave propagation time is corrected according to an angle between a line and the input device.

(Supplementary note 8) In Supplementary note 7, the correction is
The coordinate input apparatus is performed when the input device is at least a predetermined reference distance from the first and second ultrasonic receivers.

(Supplementary note 9) In Supplementary note 1, if the input device is shorter than a predetermined reference distance from the first and second ultrasonic receivers, the reception ultrasonic waves of the first and second ultrasonic receivers may be changed. The position of the input device is determined according to the first and second distances determined based on the timing of the zero-cross point of the sound wave.
According to the first ultrasonic propagation time and the phase difference,
A coordinate input device, wherein a position of the input device is obtained.

(Supplementary Note 10) A coordinate input device for inputting coordinates from an input surface to a computer, comprising: an input device having an ultrasonic receiver and movable to a desired position in the input surface; Is attached to the specified place,
A fixed unit having at least first and second ultrasonic transmitters for sequentially transmitting ultrasonic waves to an ultrasonic receiver of the input device; and the ultrasonic receiver transmitted from the first ultrasonic transmitter. Generates a first ultrasonic propagation time between the ultrasonic receiver and the first ultrasonic transmitter from the ultrasonic waves received by the ultrasonic wave generator, and generates the ultrasonic waves transmitted by the first and second ultrasonic transmitters. A coordinate input device, comprising: a receiving unit that generates a phase difference between sound waves; and a position of the input device is obtained according to the first ultrasonic wave propagation time and the phase difference.

(Supplementary Note 11) In a coordinate input device for inputting coordinates from an input surface to a computer, there is provided a main body provided with an ultrasonic transmitter (or a receiver), an infrared transmitter, and input buttons, and a bottom part of the main body. A pressure-sensitive switch for detecting a pressure when the operator touches the main body in a state where the main body is placed on a horizontal surface. A synchronization signal is transmitted every time, and the ultrasonic transmitter (or receiver) transmits (or receives) the ultrasonic wave in synchronization with the synchronization signal, and the position of the main body is determined from a distance according to the propagation time of the ultrasonic wave. Is detected, and the cursor position of the computer is updated according to the movement of the position of the main body when the pressure-sensitive switch detects the pressure.

[0104]

As described above, according to the present invention, the coordinates of the input device can be accurately obtained even when the distance between the transmitters is reduced by the ultrasonic wave, and the degree of freedom in the arrangement of the receiving unit is increased. Also,
It is possible to provide an ultrasonic mouse having operability similar to that of a mechanical mouse.

As described above, the scope of protection of the present invention is not limited to the above-described embodiment, but extends to the inventions described in the claims and their equivalents.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional method for detecting an ultrasonic reception timing.

FIG. 2 is a diagram illustrating a conventional method for detecting an ultrasonic reception timing.

FIG. 3 is a principle diagram of triangulation in the present embodiment.

FIG. 4 is a diagram illustrating a locus of a distance difference M;

FIG. 5 is a diagram showing a method for obtaining a propagation time and a phase difference from two received waves.

FIG. 6 is a diagram illustrating occurrence of ambiguity in a distance difference m obtained from a phase difference.

FIG. 7 is a diagram showing a coordinate input device according to the first embodiment.

FIG. 8 is another usage example of the coordinate input device.

FIG. 9 is another usage example of the coordinate input device.

FIG. 10 is a configuration diagram of a pen-type input device.

FIG. 11 is a configuration diagram of a receiving unit.

FIG. 12 is a configuration diagram of a coordinate input control unit.

FIG. 13 is a block diagram of a receiving unit in the receiving unit.

FIG. 14 is an operation flowchart of an input coordinate calculation unit in the coordinate input control device.

FIG. 15 is a diagram showing a measurement result of an error.

FIG. 16 is a diagram showing coordinate conversion.

FIG. 17 is a modified example of the receiving unit in the receiving unit.

18 is a timing chart illustrating the operation of the receiving unit in FIG.

FIG. 19 is a flowchart of a coordinate input operation unit in a modified example of FIGS.

FIG. 20 is a diagram showing an example applied to a three-dimensional mouse.

FIG. 21 is a diagram illustrating a receiving unit for a three-dimensional mouse.

FIG. 22 is a diagram illustrating an example of a receiving unit in the case of a three-dimensional mouse.

FIG. 23 is a configuration diagram of an ultrasonic mouse according to the second embodiment.

FIG. 24 is an internal configuration diagram of an ultrasonic mouse according to the second embodiment.

FIG. 25 is a configuration diagram of a receiving unit according to the second embodiment.

FIG. 26 is a diagram illustrating coordinate detection of an ultrasonic mouse.

FIG. 27 is a flowchart of the cursor position detection in the second embodiment.

[Explanation of symbols]

 Reference Signs List 4 input device, input pen 17 ultrasonic transmitter 18 infrared LED 54, 56 receiving unit R1, R2 ultrasonic receiver PD infrared receiving element 58 receiving unit 60 coordinate input control unit 61 input surface setting unit 62 input coordinate calculation unit L1, L2 Approximate distance M Distance difference 80 Ultrasonic mouse 81 Main body 87 Pressure sensitive switch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Fujii 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Fujitsu Limited (Reference) 5B068 AA04 BB21 BC03 BD02 BD11 BD17 BD22 BD25 BE08 BE15 CC17 CD05 CD06 5B087 AA02 BC03 BC17 BC31 CC26 CC47 DD02 DD06 DD17

Claims (5)

[Claims] 1. A coordinate input device for inputting coordinates from an input surface to a computer, comprising: an input device having an ultrasonic transmitter and movable to a desired position in the input surface; And a fixed unit having at least first and second ultrasonic receivers for receiving ultrasonic waves from an ultrasonic transmitter of the input device,
Generating a first ultrasonic propagation time between the ultrasonic transmitter and the first ultrasonic receiver from the ultrasonic wave received by the first ultrasonic receiver; A receiving unit that generates a phase difference between the ultrasonic waves received by the ultrasonic receiver,
According to the first ultrasonic propagation time and the phase difference,
A coordinate input device, wherein a position of the input device is obtained. 2. The coordinate input device according to claim 1, wherein the receiving unit generates the first ultrasonic wave propagation time at a timing when an envelope of the received ultrasonic wave exceeds a predetermined threshold. . 3. The coordinate system according to claim 1, wherein the receiving unit obtains the phase difference from a timing difference between zero-cross points of ultrasonic waves received by the first and second ultrasonic receivers. Input device. 4. The ultrasonic receiver according to claim 1, wherein said input device is less than a predetermined reference distance from said first and second ultrasonic receivers. The position of the input device is determined according to the first and second distances determined by the timing of the zero-cross point of the above. If the distance is equal to or longer than the predetermined reference distance, the first ultrasonic propagation time and the phase difference are determined. The position of the input device is obtained according to the following. 5. A coordinate input device for inputting coordinates from an input surface to a computer, wherein the ultrasonic transmitter (or receiver) is provided.
And a pressure-sensitive switch provided at the bottom of the main body, the pressure-sensitive switch being provided at the bottom of the main body and detecting pressure when an operator touches the main body while the main body is placed on a horizontal surface. In response to the pressure detection of the pressure-sensitive switch, the infrared transmitter sends out a synchronization signal at predetermined time intervals, and the ultrasonic transmitter (or receiver) emits an ultrasonic wave in synchronization with the synchronization signal. Transmitting (or receiving) the position of the main body from the distance according to the propagation time of the ultrasonic wave, and the cursor position of the computer is changed according to the movement of the position of the main body when the pressure-sensitive switch detects the pressure. A coordinate input device characterized by being updated.