JP4136417B2 - Position detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a position detection device, and more particularly to a position detection device applicable to a coordinate input device used for inputting coordinate information to a computer or the like.
[0002]
[Prior art]
As a coordinate input device (pointing device) for inputting coordinate information to a computer, a mouse, a trackball, a magnetic type, a pressure-sensitive tablet, and the like are known.
[0003]
Among these, magnetic and pressure-sensitive tablets are excellent from the viewpoints of operability and accuracy. When a magnetic or pressure-sensitive sensor plane is traced with a pen-type moving body, the coordinate position on the traced sensor plane is sensed, and the positional information is output as an electrical signal.
[0004]
[Problems to be solved by the invention]
This magnetic and pressure-sensitive tablet has excellent characteristics as described above, but the writing operation range is limited to the attached sensor plane. If this writing operation range is to be expanded, it is necessary to prepare a large device as a sensor plane, in which case the price of the sensor plane increases and a large space is required to accommodate the plane. It becomes.
[0005]
In view of the above problems, the present invention has excellent operability and accuracy similar to those of magnetic and pressure-sensitive tablets, and can be applied to a coordinate input device with a wide application range that can be widely used without limiting the writing operation range. An object is to provide a possible position detecting device.
[0006]
[Means for Solving the Problems]
The present invention receives a mobile body having means for detecting contact and means for intermittently transmitting a synchronization signal and a distance measurement signal having different propagation speeds, and receives these synchronization signal and distance measurement signal. Means for calculating the respective propagation distances of the distance measurement signal from the moving body to each of a plurality of predetermined fixed positions from the difference in reception timing, and the mutual of the plurality of propagation distances and the plurality of fixed positions. A position having means for calculating the position of the moving body from a positional relationship, and means for ignoring data based on a signal transmitted at the beginning of the stroke among distance measurement signals based on a stroke of contact with the contact surface of the moving body In the detection device, the means for ignoring data based on the first signal transmitted may indicate that the end of the previous stroke is an intermittent transmission signal interval of the synchronization signal transmitted intermittently. A position detecting device configured to determine by detecting.
In Reference Example 1, a synchronization signal and a distance measurement signal having different propagation velocities are intermittently transmitted from a mobile body , and the propagation distance to a different fixed position of the distance measurement signal is calculated from the difference in reception timing. It has a configuration for calculating the position of the moving body from the distance between the fixed positions and the calculated propagation distances, and further includes means for delaying the transmission start timing of the intermittent distance measurement signal for a predetermined time.
[0007]
According to the configuration of Reference Example 1 , even when the distance measurement signal is a sound wave signal such as an ultrasonic wave, the collision sound generated when the moving body contacts the contact surface and the distance measurement signal are clarified. It can be distinguished. That is, the collision sound is generated and propagated without a time delay when the moving body contacts the contact surface, whereas the distance measurement signal is propagated after being delayed for a predetermined time. Therefore, by making the sound wave received at an unnaturally early timing exempt from the position detection calculation, the collision sound is erroneously determined as a distance measurement signal, and this is applied to the position detection calculation to detect an incorrect position. It is possible to prevent such a situation.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
An embodiment or a reference example of the present invention is a coordinate input device for inputting coordinate information to a computer or the like, and obtains the coordinate position of a pen-type moving body as follows. That is, the distance to the moving body is measured by measuring the propagation time of the ultrasonic wave emitted by the moving body, and the coordinate position is obtained by the triangulation method. With this configuration, for example, handwritten characters by the pen-type moving body for a paper document placed on a desk can be directly input to a computer or the like.
[0010]
FIG. 1 shows the principle. That is, the pen-type moving body 10 includes an ultrasonic transmitter, and ultrasonic waves emitted from the ultrasonic transmitter of the moving body 10 are received by a plurality of receivers 50a and 50b in the fixed unit 50, By measuring the difference between the time received at each time and the time when the same ultrasonic wave is transmitted from the pen-type moving body 10, that is, the propagation time of the ultrasonic wave, the pen-type moving body 10 and the plurality of receivers 50a, 50b Each distance (propagation distance) is calculated. Then, the coordinate position of the pen-type moving body 10 is calculated by a known triangulation method based on the calculated distance and the distance between the receivers 50a and 50b measured in advance.
[0011]
In the distance calculation, it is possible to obtain the distance between the ultrasonic wave propagation times by the ultrasonic wave velocity. The propagation time is obtained as the time from the transmission timing obtained from the synchronization means 3 shown in FIG. 2A to the reception timing of the ultrasonic waves at the receivers 50a and 50b.
[0012]
Here, as shown in FIG. 2A, the pen-type moving body 10 is provided with a mechanism for detecting a writing operation by the pen-type moving body 10 of an operator, that is, a writer, for example, a pressure sensitive switch 1. When the pen tip of the pen-type moving body 10 comes into contact with a writing surface such as a paper surface on the desk, the switch 1 is turned on. When the switch 1 is turned on, ultrasonic waves are transmitted from the transmitter 5 at a predetermined time interval by the timer 2 until the switch 1 is separated from the writing surface and turned off (FIG. 2 ( In a), reference numeral 6).
[0013]
At this time, in synchronization with the transmission of the ultrasonic wave, the synchronization means 3 transmits a synchronization signal indicating the synchronization timing to the receiving-side fixed unit 50 (reference numeral 4 in FIG. 2A). By applying an optical signal generated by light emission such as infrared rays as the synchronization signal, the propagation time can be shortened to a negligible level with respect to the propagation time of the ultrasonic signal.
[0014]
Here, as shown in FIG. 2B, a case is considered where ultrasonic writing is transmitted simultaneously with detection of writing by the writing detection mechanism 1. In this case, due to the function of the timer 2, the synchronization signal and the ultrasonic signal are intermittently transmitted at a predetermined cycle defined by the timer 2, as shown in FIG.
[0015]
By the way, when performing a writing operation with the pen-type moving body 10, a collision sound is generated in a manner depending on the hardness relationship between the pen tip and the writing surface. This collision sound may have an ultrasonic component of several tens of kHz. Further, depending on the structure of the pen-type moving body 10 and the surrounding environment, the reverberation of the collision sound may continue for about several ms (FIG. 3). For this reason, not the ultrasonic wave emitted from the transmitter 5 that should be detected in the fixed unit 50 but the ultrasonic wave due to this collision sound may be detected, and as a result, the coordinate position may be erroneously detected.
[0016]
Here, as shown in FIG. 3, the factors causing the time difference Δt between the generation of the collision sound and the normal ultrasonic signal are mainly the operation time of the pressure-sensitive switch as the writing detection mechanism 1 and the ultrasonic wave. The circuit operation time of the drive circuit (transmitter) 5 can be considered.
[0017]
In order to solve the problem of erroneous detection due to the collision sound, in Reference Example 1 , as shown in FIG. 5, a delay circuit 11 is provided between the writing detection mechanism 1 and the synchronization unit 3 and the ultrasonic transmission mechanism 5. The collision sound that is a problem is generated at the beginning of each stroke in the writing operation by the operator, that is, at the first time when the pen tip of the pen-type moving body 10 contacts the writing surface. Therefore, in the present reference example , a predetermined time interval T (see FIG. 4) is provided by the delay circuit 11 after the handwriting detection in the handwriting detection mechanism 1, and after the elapse of time, intermittent transmission via the timer 2 by the transmission mechanism 5 is performed. It is set as the structure which implements transmission of a sound wave. In this way, since the waiting time after writing detection is set until the collision sound and its reverberation naturally disappear, it is possible to prevent erroneous detection of ultrasonic waves.
[0018]
That is, in the case of the reference example 1, the writing is detected by the switch 1 and then delayed by a predetermined time interval T by the delay circuit 11. The time interval T in this case is set based on the result of measuring the collision sound and the reverberation time in advance (for example, several ms). After the delay, until the end of writing is detected by detecting the contact state between the pen-type moving body 10 and the writing surface by the switch 1, the transmission of ultrasonic waves is intermittently performed at a predetermined interval (cycle) by the timer 2. Repeated. In the case of this reference example , an infrared light emitting means is used as the synchronizing means 3, and a synchronizing signal is transmitted by light emission of the infrared LED. However, the synchronization means 3 is not limited to this, and a system in which the moving body 10 and the fixed unit 50 are connected by wire and directly transmitted as an electric signal may be used.
[0019]
Next will be described the actual施例of the present invention. If it is possible to prevent the operator from being aware of the influence of the collision sound, the influence of the collision sound can be apparently eliminated. In other words, the end of each stroke of the writing operation by the pen-type moving body 10 by the operator may be detected, and the initial coordinate detection data of the next stroke starting immediately after that may not be used (ignored). As described above, this is a technique that utilizes the fact that the collision sound in question is generated only at the beginning of each stroke of the writing operation.
[0020]
In the case of this embodiment, the detection of the end of the stroke is specifically performed by, for example, detecting the transmission repetition frequency of the ultrasonic wave transmitted intermittently at a constant cycle, and detecting the repetition frequency (about 50 to 100, 200 Hz). This is done by determining whether the period is a predetermined one. That is, as shown in FIG. 5, the intermittent and periodic generation of the synchronization signal via the timer 2 is started by detecting the contact between the pen-type moving body 10 and the writing surface by the switch 1, and continues while the contact continues thereafter. Therefore, the contact detection by the switch 1 is interrupted by the end of the stroke of the writing operation, so that intermittent and periodic generation of the synchronization signal is also interrupted. As a result, a relatively long time is left until the next sync signal is started intermittently and periodically when the stroke of the next writing operation starts. Therefore, it is possible to detect a state where there is an interval as a disturbance in the period of synchronization signal reception (that is, synchronization pulse reception).
[0021]
Figure 6 illustrates the operation of the method according to the above you施例. That is, the end of the stroke is detected, and the measured value at the first time of the next stroke is ignored. Specifically, the end of the stroke is detected as follows, that is, the time interval at which the synchronization signal is sent from the moving body 10 is measured (steps S11 and S12), and the measurement result is the synchronization signal transmission. If it does not coincide with the predetermined repetition period (No in step S13), it is determined that the stroke is finished and the next stroke is started. In that case, the coordinate calculation of the moving body 10 by receiving the ultrasonic signal is not performed, and the process proceeds to step S11. Return.
[0022]
Conversely, when it is determined that the detection period of the synchronization signal is a predetermined value (Yes in step S13), reception between the synchronization signal and the ultrasonic signal is performed as described in the above embodiment and each reference example . Coordinate calculation of the pen-type moving body 10 is performed by the triangulation method from the difference in detection timing (step S14).
[0023]
In addition, even when noise due to disturbance light or the like can be erroneously detected as a synchronization signal by the configuration shown in FIG. 6, in that case, the measurement value is not applied to position calculation by detecting the disturbance as a synchronization pulse reception period. This can be dealt with.
[0024]
Next, reference example 2 will be described with reference to FIG. In this reference example , as described above, the fact that the collision sound is generated only at the initial time of the writing stroke is used, the initial time of each writing stroke is detected, and the measured value at that time is ignored.
[0025]
Specifically, by transmitting the end of the writing operation stroke from the pen-type moving body 10 on the transmitting side to the fixed unit 50 side, the fixed unit 50 side receives the collision sound and the normal ultrasonic signal. Make a distinction. The end of stroke is transmitted by a synchronization signal.
[0026]
In this reference example , an infrared light emitting means is used as the synchronization means 3 as in the above reference examples and examples. At this time, by preparing two types of pulse widths of infrared light that can be emitted in advance (pen on signal / pen off signal, see FIG. 7C), the end of stroke (pen off) can be transmitted. On the other hand, in the fixed unit 50, an initial flag by pen on / off is provided. With this flag, it is determined whether or not it is the first time of the stroke. If it is the first time, the measured value at this time is ignored.
[0027]
That is, in FIG. 7A, when the touch of the pen tip is detected from the output of the switch 1 on the moving body 10 side (Yes in step S21), the pen on signal of the two types of synchronization signals is applied. Is transmitted (step S22). At the same time, an ultrasonic signal is also transmitted (step S23). If it is determined that the repetition cycle by the function of the timer 2 has elapsed (Yes in step S24), the process returns to step S21 and restarts from the operation of determining whether or not the pen tip is touched.
[0028]
Here, when the end of the pen tip contact is detected in step S21 (No), a pen off signal that is a signal at the time of detecting the pen tip non-contact among the two types of synchronization signals has already been transmitted in step S25. Determine whether or not. If not transmitted (Yes), the pen-off signal is transmitted in step S26. On the other hand, if the call has been made (No), the process returns to step S21. In this manner, the pen-off signal is prevented from being repeatedly transmitted while the pen-type moving body 10 is separated from the writing surface.
[0029]
On the other hand, in the fixed unit 50 on the receiving side, as shown in FIG. 7B, when a synchronization signal is detected in step S31 (Yes), it is determined whether or not the signal is a pen off signal (step S32). In the case of a signal (Yes), the initial flag is set (step S33), and the measurement value at that time is ignored and the process returns to step S31. On the other hand, if the determination in step S32 is not a pen-off signal (No), it is determined whether or not it is a pen-on signal in step S34. If it is a pen-on signal (Yes), then an initial flag is set in step S35. If it is standing (Yes), the measured value at that time is ignored, and the process returns to step S31. If not standing (No), the coordinates of the moving body 10 are calculated by the triangulation method as described above using the measured value at that time in step S37.
[0030]
As described above, according to the reference example 2 , the initial flag is set at the time of detecting the pen off, the initial flag is once cleared after the detection of the pen on, and the coordinate calculation is performed from the time of detecting the next synchronization signal. As a result, the measured value in the initial stage of the writing stroke is ignored. Since the repetition frequency of the synchronization signal and the ultrasonic signal by the timer 2 is 50 to 200 Hz as described above, even if the data for several times at the beginning of the writing stroke is ignored in this way, it is not possible to detect the writing stroke such as handwritten characters. There is no hindrance.
[0031]
Next, Reference Example 3 will be described. In this reference example , the fixed unit 50 is provided with means for distinguishing between the collision sound and the normal ultrasonic signal, thereby preventing erroneous detection between the collision sound and the normal ultrasonic signal. Specifically, the collision sound generally includes a relatively large number of frequency components, whereas the frequency of the ultrasonic signal transmitted from the pen-type moving body 10 is a fixed value. Therefore, it is possible to distinguish between the collision sound and the normal ultrasonic signal by analyzing the frequency component of the received sound wave.
[0032]
FIG. 8 shows the operation of the receiving side, that is, the fixed unit 50 according to the third reference example . Here, for example, the period of the received sound wave is measured by a technique such as zero cross detection (steps S51, S52, and S53). When this period is different from the predetermined period of the ultrasonic signal transmitted from the pen-type moving body 10 (No in step S54), the received sound wave is ignored and a normal ultrasonic signal (pulse) is waited (step S56). On the other hand, when the period of the received sound wave coincides with the predetermined period (Yes in S54), the received sound wave is determined as a normal ultrasonic signal, and the pen-type moving body 10 by the triangulation method is used as described above. The coordinate calculation process is performed (step S55).
[0033]
FIG. 9 shows the configuration of the receiving side (fixed unit 50 side) according to the above-described Reference Example 3 . In the figure, since the circuits after the ultrasonic receivers 50a and 50b are the same, only the ultrasonic receiver 50a side will be described. The output of the receiver 51a is input to the input amplifier 51a, and the detection signal amplified here is used for measuring the ultrasonic wave reception timing, that is, the propagation time of the ultrasonic signal, and for measuring the period of the received sound wave. That is, the amplifier output is input to both the propagation time measurement comparator 53a and the comparator 52a for measuring the half period of the received sound wave.
[0034]
Regarding the measurement of the propagation time, the timer 59a is started by the input from the infrared PD (synchronization signal detector) 50c, and the timer 59a is stopped by the output of the comparator 53a. The time T1 measured by the timer 59a is set as the propagation time of the ultrasonic signal. The comparator 53a has a predetermined threshold, and generates an output when a sound wave having a level exceeding the threshold is received. This threshold is set to a level that can prevent detection of sound waves due to noise such as disturbance sound waves.
[0035]
On the other hand, the comparator 52a used for 1/2 period measurement of the received sound wave is a zero cross comparator, and this output is input to both the rising edge detection circuit 55a and the falling edge detection circuit 56b. Here, since the zero cross comparator 52a frequently generates pulses due to noise or the like, a signal obtained by receiving the output of the comparator 53a for measuring the propagation time with an FF (flip flop) is used as a mask. That is, extra noise is masked by ANDing the outputs of the rising and falling edge detection circuits 55a and 55b.
[0036]
The timer 60a is started by the mask output of the rising edge detection circuit 55a, and the timer 60a is stopped by the mask output of the falling edge detection circuit 56a. The time T2 obtained in this way corresponds to the zero-cross interval of the received sound wave, that is, a ½ period. (In this figure, the timer is started at the rising edge and stopped at the falling edge, but the signals used for starting and stopping may be reversed.)
That is, in the circuit of FIG. 9, the circuit by the comparator 53a and the timer 59a has a time difference T1 from the reception timing of the synchronization signal received by the infrared PD 50c to the reception timing of the ultrasonic signal received by the ultrasonic receiver 50a (ie, This is a circuit portion for measuring the “propagation time”) and performing coordinate calculation by the triangulation method from the time difference T3 of another system obtained from the circuit of the corresponding comparator 53b and timer 59b. With this configuration, a sound wave having a predetermined level and having a predetermined period is detected as a normal ultrasonic signal and applied to the coordinate position calculation of the pen-type moving body 10.
[0037]
On the other hand, the comparator 52a, the rising edge / falling edge detection circuits 55a and 56a, the AND circuits 57a and 58a, and the circuit of the timer 60a each include a timer 60a each time the received signal level crosses the zero level upward or downward. Is a circuit portion for measuring a sound wave period of a received sound wave (for example, a period corresponding to 80 kHz or the like) by starting and stopping.
[0038]
The present invention includes configurations described in the following supplementary notes.
[0039]
(Appendix 1)
A moving body comprising means for detecting contact and means for intermittently transmitting a synchronization signal and a distance measurement signal having different propagation speeds;
Means for receiving the synchronization signal and the distance measurement signal, and calculating each propagation distance of the distance measurement signal from the difference between the reception timings to each of the predetermined plurality of fixed positions;
Means for calculating the position of the moving body from the plurality of propagation distances and the mutual positional relationship of the plurality of fixed positions;
A position detecting device comprising means for delaying a transmission start time of a distance measurement signal intermittently transmitted by the means for transmitting the distance measurement signal by a predetermined time.
[0040]
(Appendix 2)
The distance measurement signal consists of an ultrasonic signal,
The position detecting device according to supplementary note 1, wherein the predetermined time is determined by a time that elapses until the reverberation of the collision sound generated when the moving body and the contact surface come into contact with each other naturally disappears.
[0041]
(Appendix 3)
A moving body comprising means for detecting contact and means for intermittently transmitting a synchronization signal and a distance measurement signal having different propagation speeds;
Means for receiving the synchronization signal and the distance measurement signal, and calculating each propagation distance of the distance measurement signal from the difference between the reception timings to each of the predetermined plurality of fixed positions;
Means for calculating the position of the moving body from the plurality of propagation distances and the mutual positional relationship of the plurality of fixed positions;
A position detection apparatus comprising means for ignoring data of a distance measurement signal based on a stroke of contact with a contact surface of the moving body, a signal transmitted at the beginning of the stroke.
[0042]
(Appendix 4)
The position according to supplementary note 3, wherein the means for ignoring data by the signal transmitted first determines the end of the previous stroke by detecting a disturbance in the transmission interval of the synchronization signal transmitted intermittently. Detection device.
[0043]
(Appendix 5)
The moving body has means for transmitting that the contact stroke is interrupted;
The position detecting device according to appendix 3, wherein the means for ignoring data by the signal transmitted first determines the end of the previous stroke based on the detection signal from the stroke interruption detecting means.
[0044]
(Appendix 6)
A means for detecting contact; and a mobile body comprising means for intermittently transmitting a synchronization signal and a distance measurement signal having different propagation speeds;
Means for receiving the synchronization signal and the distance measurement signal, and calculating each propagation distance of the distance measurement signal from the difference between the reception timings to each of the predetermined plurality of fixed positions;
It comprises means for calculating the position of the moving body from the mutual positional relationship between the plurality of propagation distances and the plurality of fixed positions,
The propagation distance calculation means is a position detection device configured to include means for identifying the distance measurement signal.
[0045]
(Appendix 7)
The distance measurement signal is an ultrasonic wave,
The position detection device according to appendix 6, wherein the means for identifying the distance measurement signal distinguishes between a collision sound generated when the moving body and the contact surface are in contact with the distance measurement signal of the ultrasonic wave.
[0046]
(Appendix 8)
The position detecting device according to appendix 7, wherein the means for identifying the distance measurement signal includes means for measuring a period of a received sound wave.
[0047]
【The invention's effect】
Thus, according to the present invention, in the configuration in which the propagation time of a distance measurement signal such as an ultrasonic wave is detected, the corresponding propagation distance is calculated, and the position of the mobile object is detected by triangulation or the like, By not applying the data at the time of first contact with the contact surface to the position detection calculation, it is possible to prevent erroneous position detection due to a collision sound or the like that can be generated only at the beginning of the contact. As a result, it is possible to realize a coordinate input device with high operability and accuracy that can widen the application range by not limiting the writing operation range.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of a coordinate input device according to an embodiment of the present invention and reference examples .
FIG. 2 is a diagram (part 1) for explaining a problem considered to be caused by the configuration of FIG. 1;
3 is a diagram (No. 2) for explaining a problem considered to be caused by the configuration of FIG. 1; FIG.
4 is a diagram for explaining the operation of Reference Example 1. FIG.
5 is a diagram for explaining the configuration of Reference Example 1. FIG.
Is a diagram for explaining the operation of the real施例of the present invention; FIG.
7 is a diagram for explaining the operation of Reference Example 2. FIG.
FIG. 8 is a diagram for explaining an operation on the reception side according to Reference Example 3 ;
FIG. 9 is a diagram for explaining a configuration on the receiving side according to Reference Example 3 ;
[Explanation of symbols]
10 Pen-type mobile unit (transmitting side)
50 Fixed unit (receiving side)
50a, 50b Ultrasonic receiver 50c Infrared receiver

Claims (1)

A moving body having means for detecting contact and means for intermittently transmitting a synchronization signal and a distance measurement signal having different propagation speeds;
Means for receiving the synchronization signal and the distance measurement signal, and calculating each propagation distance of the distance measurement signal from the difference between the reception timings to each of the predetermined plurality of fixed positions;
Means for calculating the position of the moving body from the plurality of propagation distances and the mutual positional relationship of the plurality of fixed positions;
Among the distance measurement signals based on the stroke of contact with the contact surface of the moving body, a position detection device having means for ignoring data based on a signal transmitted at the beginning of the stroke,
The means for ignoring data by the signal transmitted first determines the end of the previous stroke by detecting disturbance of the transmission interval of the synchronization signal transmitted intermittently.

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