JPH03271918A - Ultrasonic tablet - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic tablet where input from plural input pens is possible by providing plural input pens and a distributor which successively excites ultrasonic transmission elements incorporated in plural input pens one by one. CONSTITUTION:Plural input pens 1 and a distributor 4 which successively excites ultrasonic transmission elements incorporated in plural input pens 1a to 1c one by one are provided. When one input pen is excited, an ultrasonic wave is made incident on a medium 2 from this input pen and is propagated in the medium 2 and is converted to an electric signal by a detecting element 3. A time counter 9 counts the propagation time from the input pen 1 to the detecting element 3 of the ultrasonic wave to calculate the position coordinates of the input pen. The input pen is discriminated by information indicating which input pen the distributor 4 excites. The distributor 4 successively excites plural input pens 1a to 1c, and the input pen is discriminated and the position coordinates are calculated at each time of excitation. Thus, the ultrasonic tablet is realized which is provided with plural input pens 1a to 1c and where hand-written data can be simultaneously inputted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an ultrasonic tablet for manually inputting information into a computer, etc., and particularly to an ultrasonic tablet that can use multiple input pens at the same time. Regarding.

[Conventional technology]

An ultrasonic tablet uses a glass plate or the like as a writing plate, and measures the time it takes for ultrasonic waves to be incident on the writing plate from the pen tip and received by an ultrasonic detection element installed around the writing plate. The position of the pen tip on the writing board is determined based on the time, the sound speed and dimensions of the writing board, the position of the ultrasonic detection element, etc. Note that the ultrasonic waves used for this include longitudinal waves, plate waves, surface waves, and the like.

Among conventional ultrasonic tablets, one using surface waves has been proposed in Japanese Patent Application Laid-Open No. 50-50830.

Since an ultrasonic tablet can use a transparent glass plate as a writing plate, it can be combined with a liquid crystal display device or the like to form an integrated input/display tablet.

This allows handwritten information to be input by lighting up the corresponding cell of the liquid crystal display device based on the coordinate values of the input pen. Furthermore, since attributes such as the thickness and color of the input pen can be set, handwritten information can be input freely. It should be noted that this input/display integrated tablet can be constructed not only by an ultrasonic tablet but also by an electromagnetic coupling method, an electrostatic conduction method, or other tablets that can be made transparent.

[Problem to be solved by the invention]

Such an ultrasonic tablet in the above-mentioned conventional technology,
Since only one input pen can be used, attributes such as the thickness and color of the input pen must be set as necessary. However, from the user's point of view, it is more natural to switch input pens, just like switching pencils of different thickness or different colors.1 In other words, using multiple input pens If this is possible, it will be possible to provide an input/display integrated tablet that is easy to use for the user.

On the other hand, while one person is inputting handwritten information with an input pen, another person may also want to input handwritten information on the same tablet. In other words, this is a case where multiple people write together. However, conventional ultrasonic tablets can only hold one pen, which is inconvenient for multiple people to use, and it is impossible to input data at the same time.

An object of the present invention is to provide an ultrasonic tablet that allows input from multiple pens.

[Means to solve the problem]

The above object is to provide an input pen with a built-in ultrasonic transmitting element that is excited by an electric signal and generates an ultrasonic wave, a uniform isotropic medium that propagates the ultrasonic wave from the input pen, and a plurality of ultrasonic wave transmitters at the ends of the medium. It has a detection element that converts the propagated ultrasonic wave into an electric signal, and a time counter that counts the time until the ultrasonic wave propagates from the input pen to the detection element using a reference clock. An ultrasonic tablet that calculates the coordinate position of a plurality of input pens, and a distributor that sequentially excites ultrasonic transmitting elements built in each of the plurality of input pens one by one, the distributor comprising: This is achieved by identifying the input pen and calculating its position coordinates based on information indicating which input pen is excited and the count value of the time counter.

[Effect]

When one of the plurality of input pens is selectively excited by the distributor at a certain time, ultrasonic waves are incident on the medium from the corresponding input pen. The incident ultrasonic wave propagates through the medium and is converted into an electrical signal by the detection element installed at the edge of the medium.The zero time counter measures the time it takes for the ultrasonic wave to propagate from the input pen to the detection element. is counted using a reference clock, and the position coordinates of the corresponding input pen are calculated from that value. Further, the corresponding input pen is identified by information indicating which input pen is excited by the distributor. At the next time, one of the other input pens is selectively excited by the distributor, and the position coordinates and identification of the corresponding input pen are similarly performed. In this way, the distributor sequentially excites a plurality of input pens, each time calculating the identification and position coordinates of the corresponding input pen. Therefore, it is possible to realize an ultrasonic tablet equipped with a plurality of input pens and capable of simultaneous handwriting input.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 is a configuration diagram of an ultrasonic tablet according to the present invention;
The figure represents signal waveforms at various parts in FIG.

In FIG. 1, reference numeral 1 denotes an input pen with a built-in ultrasonic transmitting element, and in this embodiment, there are three input pens, 1a, 1b, and tc. 2 is input pen la, lb, l
It is a uniform isotropic medium that propagates the ultrasonic waves of 3 and serves as an input surface, and in this embodiment, a glass plate is used. 3
are detection elements that receive ultrasonic waves propagated through the glass plate 2 and convert them into electrical signals, and four detection elements 3a, 3b, 3c, and 3d are installed at some corners of the glass plate 2.

4 is a distributor that sequentially excites the ultrasonic transmitting elements built in each of the input pens la, lb, and lc one by one. 5
is a balsa that generates an electric signal to excite input vents la, lb, and lc; in this embodiment, 5a, 5b, and 5
I have three balsa c. 6 is balsa 5a, 5b
, 5c are timing circuits that determine the timing of electrical signals generated. Note that the distributor 4 includes balsa 5a, 5
b, 5c and a timing circuit 6.

7 is an amplifier circuit that amplifies the electrical signals converted by the detection elements 3a, 3b, 3c, and 3d. 8 is a waveform shaping circuit for using the electric signal from the amplifier circuit 7 to control the time counting circuit 9. 9 is a waveform shaping circuit for using the electric signal from the amplifier circuit 7 to control the time counting circuit 9. This is a time counting circuit that counts time.

lO is determined by the count value of the time counting circuit 9.
This is a position coordinate calculation circuit that calculates the position coordinates of a, lb, and lc.

Next, the operation of the ultrasonic digitizer according to one embodiment of the present invention shown in FIG. 1 will be explained with reference to FIG. 2.

The timing circuit 6 sequentially drives the balsers 5a, 5b, and 5c to output the corresponding input pens la, lb, and lc.
While exciting the built-in ultrasonic wave generating element, an instruction is issued to start counting of the time counting circuit 9, thereby,
The time counting circuit 9 starts counting based on the reference clock.

For example, at a certain timing, when the timing circuit 6 drives the balsa 5a, it excites the ultrasonic transmitting element built in the input pen la, and causes ultrasonic waves to be incident on the glass plate 2. The incident ultrasonic waves propagate through the glass plate 2 and reach the detection elements 3a, 3b, and 3c.

3d and is converted into four electrical signals. These four electrical signals pass through an amplifier circuit 7, a waveform shaping circuit 8,
The current count value of the time counting circuit 9 which has already started counting is held.

These four count values are the times tal, tbl, tcl, tdl until the ultrasonic waves emitted from the input pen 1a reach each of the detection elements 3a, 3b, 3c, and 3d.
Next, these four count values and information 1 from the timing circuit 6 indicating which input pen was excited.
1 (input pen la in the present example), the position coordinate calculation circuit lO calculates the position coordinates of the input pen la. The calculated position coordinates are transmitted to the external device via the interface 12 along with the identification information of the input pen.

At the next timing, the timing circuit 6
When the input pen 1b is driven, the ultrasonic transmitting element built in the input pen 1b is excited, and ultrasonic waves are incident on the glass plate 2. The incident ultrasonic waves propagate through the glass plate 2 and reach the detection element 3a.
, 3b, 3c, and 3d, and are converted into four systems of electrical signals. These four electrical signals pass through an amplifier circuit 7, a waveform shaping circuit 8, and a time counting circuit 9, which has already started counting.
The current count value of each is held. These four count values correspond to the times ta2, tb2, tc2, and td2 until the ultrasonic waves emitted from the input pen 1b reach the respective detection elements 3a, 3b, 3c, and 3d. The position coordinates of the input pen 1b are calculated by the position coordinate calculation circuit IO based on the count value of 1 and the information 11 from the timing circuit 6 about which input pen is excited (input pen lb in this example). . The calculated position coordinates are transmitted to the external device via the interface 12 along with the identification information of the input pen.

Furthermore, at the next timing, when the timing circuit 6 drives the balsa 5c, it excites the ultrasonic transmitting element built in the input pen IC, and causes ultrasonic waves to be incident on the glass plate 2. Thereafter, the position coordinates of the input pen 1c are calculated in the same manner.

Next, with reference to FIG. 3, a method of calculating the position coordinates of each input pen based on the count value of the time counting circuit 9, that is, a calculation performed by the position coordinate calculating circuit IO will be explained. FIG. 3 is a top view of the ultrasound tablet shown in FIG. 1. In FIG. 3, the glass plate 2 and each ultrasonic detection element 3a, 3b, 3c.

Only 3d is described for convenience of explanation.

The glass plate 2 is a rectangle with a horizontal direction X (+u) and a vertical direction Y (m). Then, the lower left corner of the glass plate 2 is defined as the origin of the XY orthogonal coordinate system. Also, change the position of the input pen l (
x, y), and the distances from the input pen l to each ultrasonic sensor are la, lb, lc.

ld (am) and the propagation time of the ultrasound wave is ta.

It is assumed that tb, tc, and td (am), and the propagation velocity of the ultrasonic wave propagating inside the glass plate 2 is V [m]. Also, the frequency of the reference clock of the time counting circuit 9 is f (Hz).
, the count values corresponding to the ultrasonic detection elements of the time counting circuit are Ca, Cb, Cc, and Cd. Therefore, l
a.

lb, lc, ld are aV la=V-La, La mini-la;-・Ca-(
1) Formula 1b=V-tb, tb=end→1b=7-Cb
・(2) Formula Cc V 1c++V'tc, tc= , -h 1c7-Cc
-(3) Formula 1d=V-td%td=end→””7-
ω...Equation (4). Also, the position coordinates of the input pen 1 (x.

y), la, lb, and X, X"+Y"=la"--(5) equation (X-x)"+y"4b'-(6) equation
Eliminate and solve for X, and then apply equations (1) and (2), x - "4" (Ca+CbXCa-Cb)
++ (7) Formula % Formula % If you solve for y in the same way, v1 y = 211 (Ca + Cd) (Ca cd) ++
<s> formula. Note that since X, Y, V, and f are constants, the count values of the time counting circuit 9 are Ca, Cb, and C.
If c and Cd are known, the position coordinates of the input pen 1 can be calculated.

As described above, the timing circuit 6 and the pulser 5a.

The distributor 4 consisting of input pens 5b and 5c has input pens la, .

By exciting lb and lc one after another and calculating the identification and position coordinates of the corresponding input pen each time,
It is possible to create an ultrasonic tablet that allows input from multiple pens at the same time.

Next, another embodiment according to the present invention will be described with reference to FIG.

The embodiment shown in FIG. 4 is an example in which a liquid crystal display device 13 is superimposed on the ultrasonic tablet of the embodiment shown in FIG. 1 as an input/display integrated tablet. The operation as an ultrasonic tablet is the same as that shown in FIG. 1, but the position coordinates of each input pen 1a, 1b, lc are calculated by the CPU 15 in place of the position coordinate calculating circuit 1O in FIG. Then, the CPU 15 causes the liquid crystal cell of the liquid crystal display device I3 corresponding to the calculated positional coordinates to be displayed via the liquid crystal drive circuit 14. This makes it possible to realize an input/display integrated tablet, which can be used, for example, as a tablet for inputting handwritten information.

According to embodiments of the present invention, it is possible to provide an ultrasound tablet that allows input from multiple pens at the same time.

In this embodiment, the case where there are four detection elements has been described, but in principle, (7).

As can be seen from equation (8), the position can be detected using three elements 3a, 3b, and 3d. The purpose of using four detection elements is that when the input pen 1 is close to the side of the glass plate 2, some detection elements generate large noise and the output of that detection element becomes unusable.

Therefore, if positioning accuracy is not so required, the effects of the present invention can be achieved even with three detection elements.

Furthermore, the input pens can be colored to be identified by color, and furthermore, the input pens can be displayed in color on a color liquid crystal display device in accordance with the inputs of the color-coded input pens.

Furthermore, it is also possible to identify the input pen by changing its thickness, and to display the input pen in a different thickness in correspondence with the input pen on the display section.

〔Effect of the invention〕

According to the present invention, an ultrasonic tablet capable of inputting from a plurality of input pens can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the ultrasonic tablet according to the present invention, FIG. 2 is a signal waveform of each part in FIG. The explanatory diagram, FIG. 4, is a diagram showing another embodiment of the present invention. Explanation of symbols 1... Input pen 2... Glass plate 3... Detection element 4... Distributor 5... Balsa 7... Amplifier circuit 9... Time counting circuit 13... Liquid crystal display device 15...CPU 6...Timing circuit 8...Waveform shaping circuit 10...Position coordinate calculation circuit 14...Liquid crystal drive circuit (Figure 5)

Claims (1)

[Claims] 1. An input pen containing an ultrasonic transmitting element that is excited by an electric signal to generate ultrasonic waves, a uniform isotropic medium that propagates the ultrasonic waves from the input pen, and an edge of the medium. A plurality of detecting elements are installed in the part, and the detecting element converts the propagated ultrasonic wave into an electric signal, and a time counter counts the time until the ultrasonic wave propagates from the input pen to the detecting element using a reference clock, An ultrasonic tablet that calculates the coordinate position of an input pen based on the count value includes a plurality of input pens and a distributor that sequentially excites ultrasonic transmitting elements built in each of the plurality of input pens one by one. An ultrasonic tablet comprising: identifying an input pen and calculating its position coordinates based on information indicating which input pen is excited by the distributor and a count value of the time counter.