JPH01116723A - Coordinate input device - Google Patents

Abstract

PURPOSE:To improve the reliability of a coordinates input by providing a means to detect the contact condition of a vibrating pen and a means to decide the valid.invalid of inputted coordinates data and constructing so as to fetch only effective coordinates information in a condition in which the vibrating pen is brought into contact with a vibration transmitting plate based on the output of the detecting and deciding means. CONSTITUTION:The title device is provided with the means to detect the contact condition of a vibrating pen 3 with a vibration transmitting plate 8 from the level of a signal detected by a vibration sensor 6 and the means to decide the valid.invalid of the coordinates data inputted from the vibrating pen 3 and constructed so as to fetch only the effective coordinates information inputted in the condition in which the vibrating pen is brought into contact with the vibration transmitting plate based on the output of the detecting and deciding means. Thus, when the vibrating pen is brought into contact with and comes off the vibration transmitting plate, a chattering phenomenon can be prevented from being caused during a pen-up and a pen-down, at the same time, the false detection of coordinates to occur in a condition in which the vibrating pen is brought into light contact with the vibration transmitting plate can be made invalid and only correct coordinates information can be inputted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects vibrations input from a coordinate input device, particularly a vibrating pen, to a vibration transmission plate by a vibration sensor provided on the vibration transmission plate. The present invention relates to a coordinate input device that detects the coordinates of a vibration input point from the above vibration transmission 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, graphics, etc. is output to a display device such as a CRT display or a recording device such as a printer.

In this type of device, ultrasonic vibrations transmitted from a vibration input pen to a tablet are input to a vibration transmission plate, detected from the input point by vibration sensors installed at predetermined parts of the vibration transmission plate, and transmitted to each sensor. A configuration is known in which the coordinates of an input point are identified by transmission time.

In this type of method that uses ultrasonic vibration, the input tablet can be constructed from a transparent material such as an acrylic plate or glass plate, so the input tablet can be placed on top of a liquid crystal display, etc., as if writing an image on paper. It is possible to configure an information input device that can be used intuitively and has a good operating feel.

[Problems to be Solved by the Invention] Figure 1θ shows the structure of a conventional ultrasonic vibration type coordinate input device.

As shown in the figure, the input tablet is constituted by a vibration transmission plate 8 whose peripheral portion is supported by a vibration isolating material 7 for preventing reflected waves. At the corner of the vibration transmission plate 8, there are a plurality of
A vibration sensor 6 consisting of several piezoelectric elements or the like is provided.

On the other hand, a vibrating pen 3 for inputting vibrations to a tablet has a vibrator 4 made of a piezoelectric element or the like, and a horn 5 for inputting vibrations of the vibrator to a vibration transmission plate 8. The vibrating pen 3 uses a vibrator drive circuit 2 in synchronization with coordinate detection processing, which will be described later.
driven by.

When a vibration is input to a desired position on the vibration transmission plate 8 using the vibration pen 3, this vibration is input to each vibration sensor 6 after a transmission time corresponding to the distance on the vibration transmission plate 8. In this case, the distance between the sensor and the input point can be determined by the product of the vibration transmission speed specific to the vibration transmission plate 8 and the transmission time.

The output of the vibration sensor 6 is transmitted through preamplifier circuits 9 to 11, vibration waveform detection circuits 12 to 14, and latch circuits 15' to 17'.
The vibration transmission time is detected by three processing circuits. The three systems of processing circuits have exactly the same configuration. Here, the circuit for the lowest hand will be explained.

The output of the vibration sensor 6 is amplified by a predetermined gain in the preamplifier circuit 9 and then input to the vibration waveform detection circuit 12 . The vibration waveform detection circuit 12 mainly detects the envelope of the detection signal, and detects input of vibration to the sensor when the envelope exceeds a predetermined level.

The detection signal of the vibration waveform detection circuit 12 is input to the latch circuit 15', and at the input timing of the detection signal, the latch circuit 15'' outputs the output data of the time counter 18, which has been started in advance in synchronization with the vibration input from the vibrating pen 3. Incorporate.

Therefore, the latch circuits 15' to 17' connected after each vibration sensor 6 store vibration transmission time data until the input vibration is input to each sensor.

As mentioned above, the distance between the input point and the vibration sensor is

It is determined by the vibration transmission speed in the vibration transmission plate 8 and time, but since the vibration transmission speed is a fixed constant, the data latched in each latch circuit 15' to 17' can be considered as distance information as it is. You can also do it.

The distance d between the vibration input point and each sensor is d=v轡t (A) where V is the vibration transmission speed in the vibration transmission plate, and t is the vibration transmission time. The time or distance information latched by each of the latch circuits 15' to 17' is input to the arithmetic control circuit 1 composed of a microprocessor, etc., and converted into coordinate information on the coordinate system set on the vibration transmission plate 8. converted.

When using an orthogonal coordinate system, coordinate information can be calculated by processing information corresponding to the straight-line distance between the latched sensor and the input point based on the Pythagorean theorem or the like.

Coordinate detection is performed as described above, and the detected coordinate information is input to other information processing devices such as computer systems, and is used for various processing such as display, recording output, and image editing.
used.

In the conventional configuration as described above, a waveform detection circuit detects the envelope, and only when the envelope exceeds a predetermined threshold value, the existence of the waveform is detected and the distance is calculated. However, with this method, the vibrating pen 3
If you press the “vibration transmission” plate 8 lightly, or if you press the vibration pen 3
When the vibration transmitting plate 8 is tilted, the waveform of the envelope signal is not constant when the vibrating pen 3 starts touching the vibration transmission plate 8 (at the start of pen-down) and when it starts to separate (at the start of pen-up), so the vibrating pen 3 moves up. , it may be interpreted as repeatedly pen-down. Alternatively, in such an unstable state, it is impossible to detect the coordinates, so that all the input coordinates are determined to be pen-up, and the input coordinates are ignored.

If the vibration detection threshold level is set low to prevent this problem, the distance will be calculated using a weak envelope signal, resulting in a decrease in coordinate detection accuracy due to a decrease in the S/N ratio.

As described above, it is difficult to determine the optimal threshold value for the envelope signal, and therefore, there is a problem in that sufficient reliability of coordinate input cannot be ensured depending on conditions such as the pen pressure of the operator.

[Means for solving the problems] In order to solve the above problems, in the present invention,
A coordinate input device that detects vibration input from a vibration pen to a vibration transmission plate by a vibration sensor provided on the vibration transmission plate, and verifies the coordinates of a vibration input point from the vibration transmission time on the vibration transmission plate. Means for detecting the contact state of the vibrating pen with the vibration transmission plate from the level of the signal detected by the sensor, and means for determining whether coordinate data input from the vibrating pen are valid or invalid are provided, and the output of the detecting and determining means is Based on this, we adopted a configuration that captures only effective coordinate information input while the vibrating pen is in contact with the vibration transmission plate.

[Operation] According to the above configuration, it is possible to determine whether or not coordinate data is to be imported based on the valid/invalid data of the coordinate information obtained from the contact state of the vibrating pen with the vibration transmission plate and the level of the vibration detection signal. There is no problem that the reliability of coordinate input decreases due to conditions such as pen pressure applied to the vibrating pen.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1(A) shows the configuration of a coordinate input device employing the present invention. In FIG. 1, members that are the same as or correspond to those of the conventional example are given the same reference numerals, and detailed explanation thereof will be omitted.

As shown in the figure, the device has an operating section that is almost the same as that of the conventional example. That is, a vibration pen 3 having a vibrator 4 and a vibration transmission plate 8 having three vibration sensors 6 supported by a vibration isolating material 7 around the vibrator 4.

Here, FIG. 1(B) shows the structure of the vibrating pen 3 and its drive system.

A vibrator 4 built into the vibrating pen 3 is connected to a vibrator drive circuit 2.
driven by. The drive signal for the vibrator 4 is shown in Figure 1 (A
) is supplied as a low-level pulse signal from an arithmetic and control circuit 1, and is applied to the vibrator 4 after being amplified by a predetermined gain by a vibrator drive circuit 2 capable of low impedance driving.

The electrical drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the vibration transmission plate 8 via the horn 5.

The vibration frequency of the vibrator 4 is selected to a value that can generate plate waves on the vibration transmission plate 8 made of acrylic, glass, or the like. Further, when driving the vibrator, a vibration mode is selected in which the vibrator 4 mainly vibrates in a direction perpendicular to the vibration transmission plate 8 as shown in FIG. 1(B). Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

The elastic waves transmitted to the vibration transmission plate 8 as described above are plate waves, which have the advantage that they are less susceptible to the effects of scratches, obstacles, etc. on the surface of the vibration transmission plate 8 compared to surface waves.

FIG. 2 shows the structure of the arithmetic control circuit 1. As shown in FIG. 2, the arithmetic control circuit 1 is composed of a microcomputer 31 and an input/output port 33. The input/output port 33 is used to output input coordinate information to another information processing device.

The arithmetic control circuit 1 also includes a drive signal generation circuit (consisting of an oscillator, etc.) 32 that generates a timing signal to be applied to the vibrator drive circuit 2.

In FIG. 2, only one system of the preamplifier, vibration waveform detection circuit, and transmission time measurement circuit is shown. 18 and the start of the time counter 18. Additionally, information on the waveform detection timing of the vibration waveform detection circuits 12 to 14 is taken in and used for control described later.

Here, the transmission time measuring circuits 15 to 17 are not mere latch circuits as in the prior art, but have a configuration as described below.

The start signal of the time counter 18 is generated by the drive signal generation circuit 3.
It is the same as the start signal in step 2, and when this signal is output from the microcomputer 31, the drive signal generation circuit 3
2 starts outputting the pulse train of the predetermined frequency, and the time counter 18 starts counting the counter clock.

On the other hand, the elastic wave signal input to the vibration sensor 6 via the vibration transmission plate 8 is converted back into an electric signal by the vibration sensor 6.
After being amplified by preamplifier circuits 9 to 11, the signals are input to vibration waveform detection circuits 12 to 14. Vibration waveform detection circuit 12
14 determine the detection timing by waveform processing to be described later, and using this detection timing signal as a trigger signal, transmission time measuring circuits 15 to 17 take in the output of the time counter 18 and transmit it to the microcomputer 31.

On the other hand, the outputs of the vibration waveform detection circuits 12 to 14 are also input to the microcomputer 31, and the next detection processing timing is determined according to this waveform detection timing signal.

By repeating the above process, the coordinates input by the vibrating pen 3 can be detected in real time.

FIG. 3 explains the detected waveforms input to the vibration waveform detection circuits 12 to 14 and the vibration transmission time measurement process based on the detected waveforms. In FIG. 3, reference numeral 41 indicates a drive signal pulse applied to the vibrating pen 3. The ultrasonic vibration transmitted from the vibrating pen 3 driven by such a waveform to the vibration transmission plate 8 passes through the vibration transmission plate 8 and is detected by the vibration sensor 6.

After traveling within the vibration transmission plate 8 for a time tg corresponding to the distance to the vibration sensor 6, the vibration reaches the vibration sensor 6. Reference numeral 42 in FIG. 3 is a vibration sensor. Therefore, the relationship between the envelope 421 and phase 422 of the detected waveform changes depending on the vibration transmission distance.

Here, the speed at which the envelope advances is assumed to be group velocity Vg, and the phase velocity is assumed to be Vp. From this difference in group velocity and phase velocity, the distance between the vibrating pen 3 and the vibration sensor 6 can be detected.

First, focusing only on the envelope 421, its speed is Vg, and when a point on a certain waveform, for example a peak, is detected as indicated by reference numeral 43 in FIG. 3, the distance d between the vibration pen 3 and the vibration sensor 6 is the vibration transmission time tg, and d=Vg"tg ・(1) Although this equation relates to one of the vibration sensors 6, the distance between the other two vibration sensors 6 and the vibration pen 3 is expressed by the same equation. be able to.

Furthermore, in order to detect coordinate values with higher precision, processing based on the detection of one phase signal is carried out at phase 422 in Fig. 3.
If tp is the time from the specific detection point of vibration application to the zero crossing point after passing the peak, then the distance between the vibration sensor and the vibration pen is d=n・λp + V p・tp
...(2) becomes. Here, input p is the wavelength of the elastic wave,
n is an integer.

From the above equations (1) and (2), the above integer nn-[(V
glltg -Vp 11tp) /input p+ 1/N
] ・”C3) (converted to an integer in []′), where N is a real number other than 0, and an appropriate value is used.For example, if N=2, and within ±1/2 wavelength, n can be determined.

By substituting n determined as above into equation (2), the distance between the vibrating pen 3 and the vibration sensor 6 can be accurately measured.

In order to measure the two vibration transmission times tg and tp shown in FIG. 3, the vibration waveform detection circuits 12 to 14 can be configured as shown in FIG. 4, for example.

In FIG. 4, the output signal of the vibration sensor 6 is amplified to a predetermined level by the aforementioned preamplifier circuits 9-11.

The amplified signal is input to an envelope detection circuit 51, 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 formed into an envelope delay time detection signal Tg having a predetermined waveform by a detection circuit 54 composed of a mono-multivibrator or the like, and is input to the arithmetic control circuit 1.

Further, the phase delay time detection signal Tp is formed by the detection circuit 57 from this Tg times signal timing and the original signal delayed by the delay time adjustment circuit 52, and the phase delay time detection signal Tp is generated by the arithmetic control circuit l.
is input.

That is, it is converted into a pulse of a predetermined width by the Tg multiplied signal monostable multivibrator 55. Further, the comparator level supply circuit 56 forms a threshold value for detecting the tp signal according to this pulse timing. As a result, the comparator level supply circuit 56 forms a signal 44 having a level and timing as indicated by reference numeral 44 in FIG. 3, and inputs it to the detection circuit 57.

That is, the monostable multivibrator 55 and the comparator level supply circuit 56 are used to ensure that the phase delay time measurement is activated only for a certain period of time after the envelope peak is detected.

This signal is sent to a detection circuit 5 consisting of a comparator etc.
7 and is compared with the delayed detection waveform as shown in FIG. 3, resulting in a tp detection pulse 45.

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 each of envelope delay time Tgl to h and phase delay time 'rpt-h are inputted to the arithmetic control circuit l.

Vibration transmission times Tg and 'rp can be detected in the manner described above.

The input coordinate value can be determined from the distance between the input point and the sensor obtained by substituting the envelope delay time Tg and phase delay time Tp thus obtained.

For example, if three vibration sensors 6 are arranged at the positions S1 to S3 at the corners of the vibration transmission plate 8 as shown in FIG.
The position P of the vibrating pen 3 is determined by the process explained in connection with the figure.
The straight line distance di-d from to the position of each vibration sensor 6
3 can be found. Furthermore, the arithmetic and control circuit 1 can determine the coordinates (x, y) of the position P of the vibrating pen 3 based on the linear distances d1 to d3 as shown in the following equation using the 3-square theorem.

! -X/2 ◆(dl+d2) (di-d2) /2
X = (4)! -Y/2 + (dl+d3) (
di-d3) /2Y...(5) Here, x and Y are the vibration sensor 6 at the positions S2 and S3 and the origin (position lEs1)
is the distance along the x and y axes of the sensor.

Next, the configuration of the circuit shown in FIG. 4 for determining the validity of the signal and the state of the pen will be described.

The envelope of the vibration detection signal output by the envelope detection circuit 51 is compared with the effective coordinate threshold 71 at a predetermined level by a comparator 73, and if it exceeds the effective coordinate level, the logical level is "l", and if it is less than the effective coordinate level, the logical level is "0". This signal is outputted to an AND gate 75, where the signals of the three circuits are ANDed, and only when all are "1", the control circuit is notified that the vibration detection signal is valid.

Similarly, comparator 74 compares the envelope to pen touch threshold 72 and OR gate 76 compares the envelope to pen touch threshold 72 .
If even one of the circuits detects contact with the pen, it notifies the arithmetic control circuit 1 that the vibrating pen 3 is in contact with the vibration transmitting plate 8.

In this embodiment, the effective coordinate threshold 71 is set to a higher voltage than the pen contact threshold 72.

Here, FIG. 6 shows the relationship between the phases 63 to 65 of the detection signal that can be output by the vibration sensor 6, the envelopes 66 to 68, the effective coordinate voltage 71, and the pen contact level voltage 72.

Further, FIG. 7 shows a process for determining the validity of input coordinate data, which is determined by the arithmetic control circuit 1 based on signals indicating the validity/invalidity of the coordinate data detected via the gates 75 and 76 and the pen contact state. On the left side of Fig. 7, AND gate 7
5 shows the possible states of the valid coordinate signal and pen contact signal output by the OR gate 76. The right side shows the states of flags set within the arithmetic control circuit 1 by the effective coordinate signal and the pen contact signal. The validity of the coordinates is determined by the state of this flag, the valid coordinate signal, and the pen contact signal.

Each detection process shown in FIG. 7 will be explained with reference to FIG. 6.

As shown in the first row of Fig. 7, when both the effective coordinate signal and the pen contact signal are rlJ (envelope 66 in Fig. 6), the pen contact flag is set to be the pen down state of rlJ, and the coordinates input at that time are The value is also valid (Figure 7, first row).

As shown in the second row of FIG. It is impossible because it is lower than E.

Next, as shown in the third row of Fig. 7, only the pen contact signal is rlJ.
In the case (envelope 67 in FIG. 6), if the pen contact flag up to that point was pen down "l", it is determined that the pen is in the pen down state. At this time, the input coordinates are valid (same as in the first row of FIG. 7).

Further, if the pen state flag up to that point was "0" for pen up, it is determined that the pen is not completely down. At this time, the input coordinate data is invalidated (7th
Figure 3rd row).

Furthermore, as shown in the fourth row of FIG. 7, when the envelope is lower than the effective coordinate threshold and the pen contact threshold (envelope 68 in FIG. 6), the pen state flag is set to pen-up "0" for the first time.

By processing the detection information in three ways in this way, it is possible to provide hysteresis in switching between pen-up and pen-down. That is, the validity of the input coordinates is determined according to the previous state of the vibrating pen indicated by the pen state flag. Therefore, when the vibrating pen touches and leaves the vibration transmission plate, it is possible to prevent the chattering phenomenon between pen down and pen up, and at the same time, it is possible to prevent the chattering phenomenon from occurring between the pen down and the pen up. This has the advantage of being able to invalidate erroneous coordinate detections that occur during the process, and allowing only accurate coordinate information to be entered.

Furthermore, when the vibrating pen is lightly touching the vibration transmission plate, it is possible to confirm that the pen is down even if the coordinates cannot be calculated.

In the embodiment described above, valid input and pen contact status are detected by detecting the envelope level and comparing it with a threshold value, but valid input and pen contact may also be detected based on the phase level.

For example, as shown in FIG.
The outputs are directly input to determination circuits 81-83. The determination circuits 81 to 83 include an effective coordinate threshold 71, a pen contact threshold 72, . . . in FIG. Comparator 73, comparator 74
is exactly the same.

In this configuration, as shown in FIGS. 9A to 9C, which correspond to FIGS. 6A to 6C, the phase signals 63 to
65, the effective coordinate level voltage 71, and the pen contact level voltage, the validity of the signal and the up/down of the pen are detected, and the logic circuit 84 combines the signals of three circuits with a predetermined logic and calculates the signal. The signal is sent to control circuit l. The validity determination process in the control circuit is the same as that shown in FIG. 7 of the above embodiment.

Furthermore, even if the judgment circuit is not provided as in each of the above embodiments,
It is possible to have hysteresis in the up and down of the pen. This means that when changing the detection flag from pen up to pen down in the arithmetic control circuit l, if the coordinate signal is input more than once, the flag is changed to 'l'.
” (pen down), and by setting the flag to “O” (pen up) when the coordinate signal is not input two or more times in a row.

In this case, the number of times of 2 or more times is 3 times, 4 times,...n
Hysteresis can be strengthened by increasing the number of times, but 1
On the other hand, it has the disadvantage that the coordinates between them are invalid.

Further, although this method cannot completely determine the validity of the coordinates, it is possible to obtain the same effects as described above using the conventional configuration without increasing costs.

[Effects of the Invention] As is clear from the above, according to the present invention, the vibration input from the vibrating pen to the vibration transmission plate is detected by the vibration sensor provided on the vibration transmission plate, and the vibration on the vibration transmission plate is detected. A coordinate input device for detecting the coordinates of a vibration input point from a transmission time, comprising: means for detecting a contact state of a vibration pen with a vibration transmission plate from the level of a signal detected by the vibration sensor; Since a configuration is adopted in which a means for determining validity/invalidity is provided and only valid coordinate information inputted while the vibrating pen is in contact with the vibration transmission plate is taken in based on the output of the detection and determining means, the vibrating pen It can prevent the chattering phenomenon between pen down and pen up when the pen touches and leaves the vibration transmission plate, and at the same time prevents the chattering phenomenon that occurs when the vibration pen lightly touches the vibration transmission plate. This has the excellent effect of invalidating false detections and allowing only accurate coordinate information to be input.

[Brief explanation of the drawing]

FIG. 1(A) is a block diagram showing the structure of a coordinate input device adopting the present invention, FIG. 1(B) is an explanatory diagram showing the structure of the vibrating pen of FIG. 1(A), and FIG. is a block diagram showing the configuration of the control circuit in FIG. 1(A), FIG. 3 is a waveform diagram showing signal processing for distance detection, and FIG. 4 is a block diagram showing the structure of the vibration waveform detection circuit. , Figure 5 is Figure 1 (A)
An explanatory diagram showing the sensor arrangement of the device, Fig. 6(A)-(
C) is a waveform diagram illustrating the level at which the envelope is determined, FIG. 7 is a waveform diagram showing operation tape phase signal determination in the control device, and FIG. 10 is a block diagram of a conventional coordinate input device. 1... Control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 7... Vibration isolating material
8... Vibration transmission plates 9-11... Preamplifier circuits 12-14... Vibration waveform detection circuits 15-17... Transmission time measurement circuit 73.74... Comparator 75... AND gate 76...OR gate Diagram 1 (B) Diagram 3 1 Tominaka Kaze〉"Su"tan η4 Ishiken no Kirime] Diagram 5

Claims (1)

[Claims] A coordinate input device that detects vibration input from a vibration pen to a vibration transmission plate by a vibration sensor provided on the vibration transmission plate, and detects coordinates of a vibration input point from a vibration transmission time on the vibration transmission plate. Means for detecting the contact state of the vibrating pen with the vibration transmission plate from the level of the signal detected by the sensor, and means for determining whether coordinate data input from the vibrating pen are valid or invalid are provided, and the output of the detecting and determining means is 1. A coordinate input device that captures only valid coordinate information input while a vibrating pen is in contact with a vibration transmitting plate.