JPS6144378A - Ultrasonic digitizer - Google Patents

Abstract

PURPOSE:To perform accurate positional detection, by calculating the position of the leading end of a display pen by receiving the signals of plural ultrasonic oscillators provided to the display pen by plural ultrasonic receivers provided on a drawing picture. CONSTITUTION:First and second ultrasonic oscillators 3, 4 are provided to a display pen 1 in the axial direction thereof and ultrasonic receivers 6-8 are provided to the corner parts on a drawing picture 5 to receive ultrasonic waves emitted from the oscillators 3, 4. From the oscillators 3, 4, the period ultrasonic waves shown by a wave form (a) are emitted and the receivers 6-8 receive the ultrasonic waves emitted with time delay to obtain the output with a wave form (b). The section of the wave form (d) from the rising of the wave form (a) to that of the wave form (b) comes to the distance data of the receivers 6-8 and the oscillators 3, 4. The position of the leading end of the display pen 1 on the drawing picture 5 is operated and calculated from the distance data (d) and the mount position data of the oscillators 3, 4 in the display pen 1.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an ultrasonic digitizer.

(Prior Art) Conventionally, a method of determining distance using an ultrasonic wave meter has already been used. That is, this method measures the time it takes for an ultrasonic wave emitted from one oscillator to reach one receiver, and calculates the distance from the measured time.

When this method is applied to a digitizer, an oscillator must be attached to the tip of the indicator pen in order to accurately detect the position. however.

Since the tip of the indicator pen is sharp, it is physically impossible to incorporate an oscillator into the tip of the indicator pen, and in reality, the oscillator is located slightly above the tip of the indicator pen.
, I have to install the device.

(Problem to be Solved by the Invention) Therefore, if we look at the position of the tip of the pointing pen and the position of the sound source of the oscillator with respect to the xy coordinates of the plane that includes the drawing surface, if the pointing pen ejects once, the sound source of this oscillation 23 XYpi
There is a problem in that an error occurs between the target and the actual XY coordinates of the tip of the pointing pen, making it impossible to accurately detect the position of the tip of the pointing pen on the drawing surface.

(Means for Solving the Problems) The ultrasonic digitizer of the present invention uses a plurality of ultrasonic oscillators and a plurality of ultrasonic receivers to detect the position of the contact point of the tip of the pointing pen on the drawing surface. , the ultrasonic oscillators are provided at intervals in the axial direction within the pointing pen, and the ultrasonic receivers are provided at intervals on the drawing surface, or.

Distance measuring means comprising ultrasonic receivers disposed at intervals in the axial direction within the pointing pen, and ultrasonic oscillators disposed at intervals on the drawing surface.

and contact point position calculation means for calculating the position of the contact point of the pointing pen on the drawing surface based on the distance from each ultrasonic oscillator to each ultrasonic receiver measured by the distance measuring means. be.

(Operation) The above means operates as follows. That is, a plurality of ultrasonic oscillators or ultrasonic receivers provided in the indicator pen and a plurality of corresponding ultrasonic receivers or ultrasonic oscillators provided on the drawing plane each generate a drawing surface. The x and y coordinates above are determined, and based on the values of the plurality of x and y coordinates, the exact position of the tip of the pointing pen on the drawing surface is calculated.

(Example) FIG. 1 shows an example of an pointing pen 1 of an ultrasonic digitizer according to the present invention, and FIG. 2 shows a state in which the pointing pen 1 is brought into contact with a drawing surface 5.

Inside the indicator pen 1, a first ultrasonic oscillator 3 of a distance measuring device 10 (see FIG. 3) is installed along the axis 2 of the indicator pen 1.
and a second ultrasonic oscillator 4. In addition, a first ultrasonic receiver 6 of the distance measuring device 10 is located at a corner of the drawing surface 5. Second ultrasonic receiver7. A third ultrasonic receiver 8 is provided respectively.

The ultrasonic waves emitted from the first ultrasonic oscillator 3 and the second ultrasonic oscillator 4 are received. Figure 3 is.

A schematic block diagram of the distance measuring device 10 is shown.

Here, a distance measuring circuit between the first ultrasonic oscillator 3 and the first ultrasonic receiver 6 will be described as an example.

In the figure, 11 is an oscillation circuit, 12 is a gate circuit, and 13 is a gate circuit.
14 is an amplifier, 14 is a waveform shaping circuit, 15 is a D-flip-flop, 16 is an AND gate, 17 is a counter, and 18 is a central processing circuit. A control signal S1 having a waveform shown in FIG. 4(a) output from the central processing circuit 18 is input to the control terminal of the gate circuit 12, and is also input to the clear terminal (CL) of the D-flip-flop 15 and the AN
Each is input to one input terminal of the D gate 16. From the waveform shaping circuit 14, an output pulse S2 having a waveform shown in FIG.
) is output.

The inverting terminal (0) of the D-flip-flop 15 outputs a signal S3 having the waveform shown in FIG. 4(C), which is set at the rising edge of the output pulse S2 of the waveform shaping circuit 14. Output terminal of AND gate 16.

The control signal S1 from the central processing circuit 18 is
It rises in synchronization with the rise of signal S3 from D-flip-flop 15, and falls in synchronization with the fall of signal S3 from D-flip-flop 15. An output pulse S4 shown in FIG. 4 (di) is output. This output pulse S4 is counted by a counter clock f,
It is output to the central processing circuit 18 as a count signal S5. In the central processing circuit 18, the nine force count signals S
5, the distance from the ultrasonic oscillator 3 to the ultrasonic receiver 6 is calculated.

In this way, the first ultrasonic oscillator 3. from the second ultrasonic oscillator 4 to the first ultrasonic receiver 6. Second wave wave receiver7.
The respective distances to the third ultrasonic receiver 8 are calculated by the central processing circuit 18 . Based on these calculated values, the positional deviation between the tip of the pointing pen and the first ultrasonic oscillator 3 and the second ultrasonic oscillator 4 is corrected by calculation, and the tip of the pointing pen on the drawing surface is corrected by calculation. Detect the exact location of.

Next, a specific calculation means for detecting the position of the tip of the pointing pen on the drawing surface by the distance measuring device having the above configuration will be explained.

In general, the propagation speed of sound waves in the air, , is the temperature t
``If it is c.

Vs = 331 +0.6 L (m/s)
-・-(represented by it. Therefore, from the first ultrasonic oscillator 3 or the second ultrasonic oscillator 4 to each first ultrasonic receiver 6. second ultrasonic receiver 7. third ultrasonic receiver The distance up to 8 is determined by measuring the time from the emission of ultrasonic waves to the reception of the ultrasonic waves.
It can be determined from the propagation velocity V3 determined using equation (1).

Now, as shown in Figure 5.

The distance between the first ultrasonic receiver 6 and the second ultrasonic receiver 7 is a.

The distance between the second ultrasonic receiver 7 and the third ultrasonic receiver 8 is the distance between the second ultrasonic receiver 7 and the third ultrasonic receiver 8.

The first ultrasonic wave receiver 6 from the first ultrasonic wave oscillator 3 determined by the distance measuring device. When the distances to the second ultrasonic receiver 7 and the third ultrasonic receiver 8 are α1°βI+7++, respectively, it is expressed by XY of the sound source Sl of the first ultrasonic oscillator 3. Similarly, from the second ultrasonic oscillator 4 to the first ultrasonic receiver 6. Second ultrasonic receiver7. The distances to the third ultrasonic receiver 8 are determined, α2°β2. Assuming γ2,
XYZ coordinates (Xz,
'It, hz) is.

It is expressed as

Further, the distance i%lf J from the tip of the pointing pen 1 to the sound source S1 of the first ultrasonic oscillator 3 is expressed as the value of each xyz coordinate obtained by equation 21 (31) above.

becomes.

On the other hand, the xy coordinates (xp, yp) of the point P on the drawing surface 5 that the tip of the pointing pen 1 actually contacts are as follows.

Therefore, by substituting the equation (21, (31, +4j) into the equation (5) and calculating it, the position of the point P on the drawing surface 5 can be accurately detected. It will be held in

In the above embodiment, two ultrasonic oscillators are provided in the indicator pen and three ultrasonic receivers are provided on the fif screen, but two ultrasonic receivers are provided in the indicator pen. , three ultrasonic oscillators may be provided on the drawing surface. In this case as well, it is possible to accurately detect the position of the pointing pen contact point on the drawing surface in exactly the same manner as in the above embodiment. Further, the number of ultrasonic oscillators and ultrasonic receivers is not limited to the above embodiment.

(Effects of the Invention) As explained above, the ultrasonic digitizer of the present invention measures the distance from a plurality of ultrasonic oscillators to a plurality of ultrasonic receivers, and according to this measured distance, Since the position is determined by calculation, it is possible to correct the error caused by the tilt of the pointing pen and to accurately detect the position of the tip of the pointing pen.

Moreover, the mounting position of the ultrasonic oscillator or ultrasonic receiver within the indicator pen can be freely selected.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, in which FIG. 1 is a perspective view of the pointing pen, FIG. 2 is a perspective view showing the drawing surface and the pointing pen, and FIG. 3 is a perspective view of the pointing pen.
The figure is a schematic block diagram of the distance measuring device, Figures 4(a) to 4(f)
dl is a diagram showing the waveforms of each part of the distance measuring device shown in FIG. 3, and FIG. 5 is a diagram showing the xyz coordinate system on the drawing surface. 1... Indication pen 3... First ultrasonic oscillator 4... Second ultrasonic oscillator 5... Drawing surface 6... First ultrasonic receiver 7... Second ultrasonic receiver 8...Third ultrasonic receiver 11...Oscillation circuit 12...Gate circuit 13...Amplifier 14...Waveform shaping circuit 15...D-flip-flop 16...AND gate 17・・・Counter 1 day・
...Central processing circuit and 1 other person Fig. 1 112 Fig. M3 Fig. 1 δ Fig. 4 (cf) ' ゛ Fig. 5

Claims (1)

[Claims] 1) In detecting the position of a contact point of the tip of an indicator pen on a drawing surface, the ultrasonic oscillator has a plurality of ultrasonic oscillators and a plurality of ultrasonic receivers, and the ultrasonic oscillator is connected to the tip of the indicator pen. The ultrasonic receivers are provided with an interval in the axial direction within the indicator pen, and the ultrasonic receivers are provided with an interval in the axial direction on the drawing surface, or the ultrasonic receivers are provided with an interval in the axial direction within the indicator pen. a distance measuring means in which ultrasonic oscillators are provided at intervals on the drawing surface, and a distance measuring means from each ultrasonic oscillator to each ultrasonic receiver measured by the distance measuring means 1. An ultrasonic digitizer comprising contact point position calculation means for calculating the position of a contact point of an indicator pen on a drawing surface based on the above.