JPH0562773B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a coordinate input device, in particular, detects vibrations input to a vibration transmission plate using a plurality of sensors provided on the vibration transmission plate, and detects vibrations on the vibration transmission plate. The present invention relates to a coordinate input device that detects the coordinates of a vibration input point on a vibration transmission plate from a delay time.

[Prior Art] Coordinate input devices using various input pens, tablets, etc. have been known as devices for inputting handwritten characters, figures, etc. to a processing device such as a computer. In this type of system, input image information consisting of characters, figures, etc. is output to a display device such as a CRT display or a recording device such as a printer.

The following various methods are known for detecting the coordinates of a tablet in this type of device.

(1) A method that detects changes in the resistance value of a sheet material placed opposite the resistive film.

(2) A method that detects electromagnetic or electrostatic induction from conductive sheets placed opposite each other.

(3) A method that detects ultrasonic vibrations transmitted from the input pen to the tablet.

In the methods (1) and (2) above, it is difficult to form a transparent tablet because a resistive film or a conductive film is used. On the other hand, in method (3), the tablet can be constructed from transparent materials such as acrylic plates and glass plates, so
Therefore, by placing an input tablet on a liquid crystal display or the like, it is possible to construct an information input/output device that is easy to operate and can be used as if writing images on paper.

[Problems to be Solved by the Invention] However, the above-mentioned ultrasonic vibration method has a problem in that it requires a special input pen called a vibrating pen. In other words, it is quite cumbersome to carry out input work by dragging a vibrating pen around with signal lines for synchronizing with the vibration detection side and signal lines for supplying power supply voltage. There is a problem that the operability is inferior compared to other methods that can perform this.

[Means for Solving the Problems] In order to solve the above problems, the coordinate input device of the present invention includes a first vibration transmission member made of the same material as the first vibration transmission member. is,
a second vibration transmission member having substantially the same thickness, a vibration detection means provided on the first vibration transmission member, a vibration generation means provided on the second vibration transmission member, and a vibration generation means provided on the second vibration transmission member; When the first vibration transmission member and the second vibration transmission member are brought into contact by pressing the vibration transmission member or the second vibration transmission member, the vibration detection means of the first vibration transmission member A configuration is adopted that includes deriving means for deriving the coordinates of the pressing point of the first vibration transmitting member or the second vibration transmitting member based on the detected vibration.

[Function] According to the above configuration, without using a special member such as a vibrating pen, the first or second vibration transmitting member is pressed with a finger, an ordinary pen, a pencil, etc. to bring them into contact, and the second vibration transmitting member is pressed. Detecting vibration input from the vibration generating means of the vibration transmitting member to the first vibration transmitting member via the contact point by the vibration detecting means of the first vibration transmitting member, and deriving the coordinates of the pressing point based on the detected vibration. I can do it.

[Examples] The present invention will be described in detail below based on examples shown in the drawings.

1A and 1B show the structure of a coordinate input device employing the present invention. The device shown in FIG. 1 is designed to allow coordinate input by directly operating a tablet with a finger, pencil, etc., without using a special member such as a vibrating pen. FIG. 1B shows the tablet in an exploded state, and FIG. 1A shows it in an assembled state.

The one designated by the reference numeral 8a in FIGS. 1A and 1B transmits vibrations transmitted by a vibration transmission plate made of acrylic, glass, etc. to two vibration sensors 6 provided at its corners. The vibration transmitting plate 8a is supported at its peripheral portion by an anti-reflection material 7 made of silicone rubber or the like in order to prevent transmitted vibrations from being reflected at the peripheral portion and returning toward the central portion. .

The vibration sensor 6 provided at the corner of the vibration transmission plate 8a is composed of a mechanical to electrical conversion element such as a piezoelectric element. The output signals of each of the two vibration sensors 6 are input to the waveform detection circuit 9, and are converted into detection signals that can be processed by the subsequent arithmetic control circuit 1.

In this embodiment, a vibration transmission plate 8b is provided as a member for inputting vibrations to the vibration transmission plate 8a. The vibration transmission plate 8b is made of the same material as the vibration transmission plate 8a and supported by an antireflection material 7, and two vibrators 4 made of piezoelectric elements or the like are provided at one corner of the vibration transmission plate 8b. This vibrator 4 is driven by a vibrator drive circuit 2.

The vibration frequency of the vibrator 4 is selected to a value that can generate plate waves on the vibration transmission plates 8a, 8b made of acrylic, glass, or the like. When a plate wave is used for vibration transmission, an advantage can be obtained that it is less affected by scratches, obstacles, etc. on the surface of the vibration transmission plate 8a, compared to surface waves.

The vibration transmission plate 8b provided with the vibrator 4 is placed under the vibration transmission plate 8a having the vibration sensor 6 as shown in FIG.
As shown in FIG. 3, they are arranged opposite to each other with a predetermined distance between them with a spacer 8c interposed therebetween.

The vibration of the vibrator 4 is transmitted to the lower side by the operator deforming the upper vibration transmitting plate 8b by pressing down with his finger F as shown in FIG. 2A, and bringing it into contact with the lower vibration transmitting plate 8a. The vibration is transmitted to the vibration transmission plate 8a. The vibration of the upper vibration transmission plate 8b is transferred to the vibration transmission plates 8a, 8.
The vibration is transmitted to the vibration transmission plate 8a via the contact point P of b. Therefore, by detecting vibration using the vibration sensor 6 and measuring the vibration delay time, the coordinates of the contact point P can be detected by finger operation.

The above-mentioned vibrators 4 are not driven simultaneously, but are driven in a time-division manner, and coordinate calculation is performed based on the vibration transmission time obtained using each vibrator.

The arithmetic control circuit 1 measures the vibration transmission time from the output of the signal waveform detection circuit 9, and detects the coordinate position of the input point P on the vibration transmission plate 8a.

The configuration and coordinate calculation processing of the calculation control circuit 1 will be described in detail below.

FIG. 3 shows the structure of the arithmetic and control circuit 1 of FIG. 1, that is, the structure of the drive system of the vibrator 4 of the vibration transmission plate 8b and the vibration detection system using the vibration sensor 6 of the vibration transmission plate 8a.

The microcomputer 11 has an internal counter,
Built-in ROM and RAM. The drive signal generation circuit 12 outputs a drive pulse of a predetermined frequency to the vibrator drive circuit 2 shown in FIG. 1, and is activated by the microcomputer 11 in synchronization with the coordinate calculation circuit.

The calculated value of counter 13 is latched into latch circuit 14 by microcomputer 11.

On the other hand, the waveform detection circuit 9 in FIG. 1 outputs timing information of a detection signal for measuring vibration transmission time for coordinate detection based on analysis of the signal waveform from the output of the vibration sensor 6 (described later). . This timing information is input to each input port 15.

The timing signal inputted from the waveform detection circuit 9 is inputted to the input port 15, and is compared with the count value in the latch circuit 14 by the determination circuit 16, and the result is transmitted to the microcomputer 11. That is, the vibration transmission time is expressed as the latch value of the output data of the counter 13, and coordinate calculations are performed using this vibration transmission time value.

FIG. 4 explains the detected waveform input to the waveform detection circuit 9 of FIG. 1 and the vibration transmission time measurement process based on the detected waveform. Number 4 in Figure 4
1 is a drive signal pulse applied to the vibrator 4 of the vibration transmission plate 8b.

The vibration transmitted from the vibration transmission plate 8b to the vibration transmission plate 8a travels within the vibration transmission plate 8a for a time tg corresponding to the distance to the vibration sensor 6, and then reaches the vibration sensor 6. Reference numeral 42 in FIG. 4 indicates a signal waveform detected by the vibration sensor 6.
The plate wave used in this embodiment is a dispersive wave, and therefore the envelope 421 and phase 42 of the detected waveform vary with respect to the propagation distance within the vibration transmission plate 8a.
2 changes depending on the transmission distance during vibration transmission.

Here, the advancing speed of the envelope is group velocity Vg,
Let the phase velocity be Vp. The distance between the vibration input point P and the vibration sensor 6 can be detected from the difference in group velocity and phase velocity.

First, if we focus only on the envelope 421,
Its velocity is Vg, and the point on a certain waveform,
For example, when a peak is detected as indicated by reference numeral 43 in FIG. 4, the distance d between the vibration input point P and the vibration sensor 6 becomes d=Vg·tg (1) where the vibration transmission time is tg.

Although this equation relates to one of the vibration sensors 6, the distances between the other two vibration sensors 6 and the vibration input point P can be expressed using the same equation.

Furthermore, in order to determine coordinate values with higher precision, processing based on phase signal detection is performed. Fourth
If tp is the time from a specific detection point of the phase waveform 422 in the figure, for example, the time from vibration application to the zero crossing point after passing the peak, then the distance d between the vibration sensor and the vibration input point is d=n・λp+Vp・tp...( 2) becomes. Here, λp is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integer n is shown as n=[(Vg·tg−Vp·tp)/λp+1/N] (3). Here, N is a real number other than 0, and an appropriate value is used. For example, if N=2, ±
If it is within 1/2 wavelength, n can be determined. n obtained as described above can be determined.

By substituting n determined as above into equation (2), the distance between the vibration input point P and the vibration sensor 6 can be accurately measured.

Since two transducers 4 are provided in the configuration shown in FIG.
is driven to calculate the distance information obtained by that vibrator, and then the other vibrator is driven to calculate the distance information obtained by that vibrator.

The two vibration transmission times tg and tp shown in Figure 4
The measurement is performed by the waveform detection circuit 9 shown in FIG. The waveform detection circuit 9 is constructed as shown in FIG.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by a preamplifier circuit 51. The amplified signal is sent to the envelope detection circuit 52.
, and only the envelope of the detection signal is extracted. The timing of the extracted envelope peak is detected by the envelope peak detection circuit 53. The peak detection signal is detected by a signal detection circuit 54 composed of a mono multivibrator, etc.
As a result, an envelope delay time detection signal Tg having a predetermined waveform is formed and input to the arithmetic control circuit 1.

In addition, this Tg signal and the delay time adjustment circuit 57
A phase delay time detection signal Tp is formed by the comparator detection circuit 58 from the original signal delayed by , and is input to the arithmetic control circuit 1.

The circuit shown above is for one vibration sensor 6, and the same circuit is provided for each of the other sensors. If the number of sensors is generalized to h, then h detection signals of envelope delay times Tg1 to h and phase delay times Tp1 to h are input to the arithmetic control circuit 1, respectively.

In the arithmetic control circuit of Fig. 3, the above Tg1 to h,
The Tp1 to h signals are inputted from the input port 15, and the count value of the counter 13 is taken into the latch circuit 14 using each timing as a trigger. As described above, since the counter 13 is started in synchronization with the driving of the vibrator, the latch circuit 14 receives data indicating the respective delay times of the envelope and the phase.

As shown in FIG. 6, the position where the vibration sensor 6 and the vibrator 4 are arranged at the corner of the vibration transmission plate 8a is denoted by S.
1 to S3, and the straight-line distances between each position S1 to S3 and the input point P are _d1 to _d3 . At this time, the straight line distance d ₁
~d Based on ₃ , the coordinates of the position P of the vibration input point P (x,
y) is expressed by the following formula from the 3-square theorem.

x=X/2+( _d1 + _d2 )( _d1 - _d2 )/2X...(4) y=Y/2+( _d1 + _d3 )( _d1 - _d3 )/2Y...(5) Here, X and Y are the distances along the X and Y axes between the vibration sensor 6 at the positions S2 and S and the sensor at the origin S1.

Here, the sum and difference of distances d ₁ to d ₃ are A
= d ₁ + d ₂ , B = d ₁ - d ₂ , C = d ₁ + d ₃ , D = d ₁ - _{d 3}
Let's define it as

On the other hand, as shown in FIG. 1, the vibrator 4 of the vibration transmission plate 8b is at the origin position S1 and the position S2 in FIG.
It is also assumed that the vibration sensors are installed at positions S2 and S3, respectively.

In this case, as is clear from FIG. 6, S2,
The distance information obtained by the vibration sensor 6 at each position of S3 is as follows since the vibration is transmitted through both the vibration transmission plates 8a and 8b.

First, when the vibrator at position S1 is vibrated, S2: d ₁ + d ₂ = A Also, at position S3, the vibrations of the two vibrators at positions S1 and S2 are input, so regarding the vibrator at position S1, S3: d ₁ + d ₃ = C For the oscillator at position S2 S3: d ₂ + d ₃ = I Therefore, from the two acquired information C, I at position S3, B = d ₁ - d ₂ , D = d ₁ - d ₃ By substituting these A, B, C, and D into equations (4) and (5), the coordinates (x, y) of the vibration input point P can be determined in real time. .

Since the above values of I, A, and C are calculated from the above equations (2) and (3), respectively, the group velocity Vg and phase velocity Vp of the vibration transmission plates 8a and 8b must be equal. In other words, since the vibration transmission plates 8a and 8b must have the same characteristics as a medium, the vibration transmission plates 8a and 8b must be made of the same material and have the same thickness.

Since there are no other restrictions, the vibration transmission plate 8a,
It is conceivable that 8b is constructed from a transparent plate made of glass, acrylic, etc., and used by stacking it on a display device such as a CRT display. In this case, a dot is displayed on the display corresponding to the coordinates of the detected vibration input point, and an image composed of elements such as points and lines input with a finger is displayed as if it were written on paper. It can be displayed in a summery manner.

Further, according to such a configuration, it is also possible to use an input method such as displaying a menu on the display and having the user select the menu item with a finger, or displaying a prompt and touching the finger at a predetermined position.

Alternatively, if the vibration transmission plate does not need to be transparent, metal or the like may be used as the material.

Vibration sensor 6 or vibration transmission plate 8 of vibrator 4
The mounting positions for a and 8b are not limited to the above and can be selected from various positions. however,
The method of coordinate calculation will be different.

FIG. 7 shows different arrangements of vibration sensors 6 and vibrators 4. In this embodiment, the vibrators 4 are provided at positions S1 to S3 of the vibration transmission plate 8b in FIG. 8, and the sensors of the vibration transmission plate 8a are provided at positions S2, S3, and S4 in FIG. 8.

In such a configuration, the coordinate calculation formula based on the straight line distance determined from the vibration delay time is as follows.

x=X/2+( _d1 + _d2 )( _d1 - _d2 )/2X...(4) (Formula (4) above) or =X/2+( _d3 + _d4 )( _d3 - _d4 ) /2X...(6) and y=Y/2+( _d1 + _d3 )( _d1 - _d3 )/2Y...(5) (Formula (5) above) or =Y/2+( _d2 + _d4 ) )(d ₂ - d ₄ )/2Y...(7) The x coordinate can be found from either equation (4) or (6) above, and the y coordinate can be found from either equation (5) or (7). .
Only one of formulas (4), (6) to (5), and (7) may be used, but here, the average value of x obtained by formulas (4) and (6), respectively, is used to detect the x coordinate. , (5), and (7), respectively, and the average value of y is determined as the detected y coordinate.

The data necessary for the above coordinate calculation uses all equations (4) to (7), so in addition to A to D consisting of the sum and difference of the distances d ₁ , d ₂ and d ₁ , d ₃ , E = _d3 + _d4 ,F= _d3 - _d4 ,G=
d ₂ + d ₄ and H=d ₂ −d ₄ are required.

On the other hand, the distance information obtained by each vibration sensor is as follows.

First, using the vibrator at position S1,
Using the sensor at S2: d ₁ + d ₂ = A S3: d ₁ + d ₃ = C Using the vibrator at position S2, using the sensor at positions S3 and S4, S3: d ₂ + d ₃ = I S4: d ₂ + d ₄ = G Using the transducer at position S3 and the sensor at position S4, S4: d ₃ + d ₄ = E From each of these combinations, the remaining D, B, F, H
can be calculated. Therefore, by substituting each obtained value into the above equations (4) to (7) to obtain two types of x and y, and averaging them, the final coordinates of the input point P (x, y) can be obtained.

According to the average value method using such different vibration transmission paths, coordinate detection accuracy can be greatly improved. For example, even if a vibration transmission path toward one vibration sensor is obstructed by an obstacle or the like, as long as the path toward one vibration sensor is normal, detection will not become impossible or accuracy will not deteriorate.

In the above example, a configuration in which vibration sensors and vibrators are provided at two locations or three locations each is illustrated, but the number of sensors and vibrators may be reduced.

For example, as shown in FIGS. 9 and 10, a configuration can be considered in which one vibrator is provided at position S1, and one vibrator is provided at each of positions S1 and S2.

In this case, the coordinate calculation formula is x=1/2X+( _d1 + _d2 )( _d1 - _d2 )/ ^2X ...(8) y= _√12-2 ^... (9). On the other hand, the sensors at positions S1 and S2 can each obtain information of S1:2d ₁ S2:d ₁ + d ₂ , so we can calculate the distance d ₁ from the sensor at position S1 and d ₁ − from the combination of the acquired information of the two sensors. By obtaining d ₂ and substituting it into the above equations (8) and (9), the coordinates (x, y) of the input point P are obtained. In this embodiment, the sensor and the vibrator need to be placed at both ends of one side of the vibration transmission plate. If they are arranged diagonally, coordinate detection is impossible because it is impossible to determine from which side of the diagonal line between the sensor and the vibrator the vibration is transmitted.

According to such a method, it is possible to reduce the number of parts, simplify calculations, and improve processing speed.

As described above, various possibilities can be considered for the number and arrangement of vibrators and vibration sensors. In the above embodiment, the vibrator is provided on the upper vibration transmission plate 8b, but
A similar configuration is possible even if the vibrator is provided on the lower side and the sensor is provided on the upper vibration transmission plate.

In addition to the configurations shown in FIGS. 9 and 10, the upper vibration transmission plate 8b may be covered with another vibration transmission plate 8d as shown in FIG.

Furthermore, even if the vibrator and the vibration sensor are arranged separately on three or more vibration transmission plates arranged opposite to each other as shown in FIG. 12, the same coordinate input can be performed. Here, in the arrangement of the sensors and vibrators in FIGS. 9 and 11, one of the sensors is provided on the upper vibration transmission plate 8d. Even with this method
Similar coordinate calculations can be performed based on equations (8) and (9).

[Effects of the Invention] As is clear from the above, according to the coordinate input device of the present invention, the first vibration transmission member is made of the same material as the first vibration transmission member and has approximately the same thickness. a second vibration transmission member having a second vibration transmission member, a vibration detection means provided on the first vibration transmission member, a vibration generation means provided on the second vibration transmission member, and a first vibration transmission member or By pressing the second vibration transmission member, when the first vibration transmission member and the second vibration transmission member are brought into contact, the vibration detected by the vibration detection means of the first vibration transmission member is Based on this, a configuration is adopted that includes a deriving means for deriving the coordinates of the pressing point of the first vibration transmitting member or the second vibration transmitting member, so there is no need for a means such as a vibration input pen. ,hand,
It is possible to provide an excellent coordinate input device that allows coordinate input by means such as a pencil.

[Brief explanation of the drawing]

Figures 1A and B are explanatory diagrams showing the configuration of a coordinate input device adopting the present invention, Figure 2A is an explanatory diagram showing a coordinate input operation, and Figure 2B is an illustration showing the arrangement of a vibration transmission plate. FIG. 3 is a block diagram showing the structure of the arithmetic and control circuit shown in FIG. Figure 5 is a block diagram showing the configuration of the waveform detection circuit in Figure 1, Figure 6 is an explanatory diagram showing the arrangement of the vibration sensor, and Figures 7 and 8.
The figures are explanatory diagrams showing the arrangement of vibration sensors and vibrators in different embodiments, Figure 9 and Figure 1.
FIG. 0 is an explanatory diagram showing further different arrangements of vibration sensors and vibrators, and FIGS. 11 and 12 are explanatory diagrams showing further different arrangements of vibration sensors and vibrators, respectively. 1... Arithmetic control circuit, 4... Vibrator, 6... Vibration sensor, 8a, 8b... Vibration transmission plate, 15...
Input port, 51... Preamplifier, 52... Envelope detection circuit, 54, 58... Signal detection circuit, 59... A/D conversion circuit.

Claims (1)

[Scope of Claims] 1: a first vibration transmission member; a second vibration transmission member made of the same material as the first vibration transmission member and having substantially the same thickness; and the first vibration transmission member. Vibration detecting means provided on the member; Vibration generating means provided on the second vibration transmitting member; By pressing the first vibration transmitting member or the second vibration transmitting member, the first vibration transmitting member is pressed. When the vibration transmitting member and the second vibration transmitting member are brought into contact, the vibration of the first vibration transmitting member or the second vibration transmitting member is detected based on the vibration detected by the vibration detecting means of the first vibration transmitting member. A coordinate input device comprising: derivation means for deriving the coordinates of a pressing point of a transmission member.