JP2009181409A - Handwriting input system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that in a conventional handwriting input system using a plurality of electronic pens, it is required to register an identification number of each electronic pen to be used in a receiver in advance, and registration is required every time an unregistered electronic pen is added or the pen is changed during use, while a CPU having high-speed calculation function is needed, thereby increasing the price. <P>SOLUTION: In the handwriting input system, the electronic pen includes an infrared receiving part including an infrared receiving element, and a signal transmitting part which stops transmission of infrared signal and ultrasonic signal for a fixed period according to reception of infrared signal. According to this, an inexpensive electronic pen can be provided, and a plurality of electronic pens can be used without interference even if the identification number of the electronic pen to be used in the receiver is not registered in advance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes an electronic pen that transmits at least an infrared signal and an ultrasonic signal, and means for receiving the infrared signal and the ultrasonic signal and calculating a position coordinate of the electronic pen from the arrival time difference thereof About the system.

Conventionally, a position detection technique of an electronic pen using an infrared signal or an ultrasonic signal is known. For example, in Japanese Patent Application Laid-Open No. Sho 62-175721 (see Patent Document 1) and US Pat. No. 4,814,552 (see Patent Document 2), an ultrasonic signal or an infrared signal and an ultrasonic wave are transmitted from an electronic pen. A technique is disclosed in which signals are generated, those signals are received by a receiving unit, and the position coordinates of the electronic pen are calculated based on the time of flight of the ultrasonic signal.

  A handwritten handwriting input system using these position detection techniques is, for example, as follows. A writer writes characters and figures using an electronic pen. At this time, the electronic pen may incorporate a ballpoint pen, for example, so that a recording medium such as paper may be used as a writing surface, and handwriting may be recorded on the recording medium. The electronic pen may include a stylus, for example. Any surface including the surface of the liquid crystal display may be used as a writing surface. At least while the pen tip of the electronic pen is in contact with the writing surface, infrared signals and ultrasonic signals are repeatedly transmitted from the electronic pen, and the receiving unit receives the infrared signals and ultrasonic signals transmitted from the electronic pen. Then, the flight time of the ultrasonic signal is measured from the difference between the arrival time of the infrared signal and the arrival time of the ultrasonic signal, and the coordinate calculation unit calculates the position coordinate data of the electronic pen from the flight time of the ultrasonic signal.

In the conversion from position coordinate data to handwriting data, information expressing features such as handwriting data derived from the handwriting written by the writer is added to the position coordinate data, or individual positions based on these features are added. This refers to processing for modifying the coordinate data, and includes, for example, any of the following processing. Information on the time when the position coordinate data is received is added. Based on the acquisition interval of the position coordinate data, the writing speed is calculated, or a set of position coordinates is identified as one stroke data including the writing order and speed as information. The continuous position coordinate data constituting one stroke data is corrected so as to draw a smooth line. Further, based on conditions such as extraction and integration of circumscribed rectangles of stroke data and restriction of writing position, the stroke data is grouped into character group data including information such as the order of writing.

The handwriting data input by the handwriting handwriting input system is displayed on the screen of an electronic device, used as code data through character recognition processing, etc., or writing such as handwriting shape, speed of handwriting, stopping, splashing, and brushing. It may be used for arbitrary purposes such as extracting the characteristics of a writer's character including characteristics and signature verification. Moreover, if it is the structure which supplies a power supply to the whole handwriting handwriting input system, the use will be possible outdoors and a use application will increase significantly. In addition, when used in combination with character recognition conversion software that converts handwriting data into character data for use in a word processor, etc., it can be used as an input means that can easily input characters, pictures, symbols, etc. by hand as well as character data. Attention has been paid.

When a handwritten handwriting input system is used by a plurality of people, such as at a meeting, a configuration in which there is one receiver and a plurality of electronic pens is conceivable. When writing with other electronic pens while writing with any electronic pen, or when writing with multiple electronic pens, the receiver cannot identify which electronic pen emits an infrared or ultrasonic signal. Therefore, the handwriting may not be reproduced correctly. Further, the ultrasonic signals transmitted from the respective electronic pens are combined with each other, and the arrival time of the ultrasonic signals cannot be accurately measured, and there is a possibility that the handwriting cannot be reproduced at all.

As a method for using a plurality of electronic pens without interference in a handwriting input system, Japanese Patent Application Laid-Open No. 2004-199560 limits the number of electronic pens that can be used from the repeated transmission interval of ultrasonic signals and the writing area. However, the receiver transmits the infrared signal including the identification number as many as the number of electronic pens in the writing area, and the electronic pen analyzes the identification number of the received infrared signal and finds its own identification number. A handwriting handwriting input system is disclosed in which a receiver can measure the position coordinates of a plurality of pens by transmitting an ultrasonic signal.

JP-A-62-175821 U.S. Pat. No. 4,814,552 Japanese Patent Laid-Open No. 2004-199560

However, the handwriting handwriting input system described in the above-mentioned Patent Document 3 needs to register the identification number of each electronic pen used in the receiver in advance, and write by adding an electronic pen not registered in advance during use. When changing to an electronic pen that has not been registered in advance, it is necessary to register again with the receiver. Further, since the electronic pen needs to analyze the identification number from the received infrared signal and collate it with its own identification number, it is necessary to use a CPU capable of high-speed calculation processing, which is expensive.
The present invention has been made to solve the above-described problem, and is a low-cost electronic pen that includes a plurality of electronic pens without interference even if the identification number of the electronic pen used for the receiver is not registered in advance. It aims at realizing the handwriting handwriting input system which can be used.

The present invention has at least an infrared transmitter including an infrared generator and an ultrasonic transmitter including an ultrasonic generator, and repeatedly transmits an infrared signal and an ultrasonic signal from the infrared transmitter and the ultrasonic transmitter. A signal transmitting unit, an infrared measuring unit having an infrared receiving unit including an infrared receiving element, a writing unit having a function capable of directly leaving a locus on a recording medium, and whether the writing unit is in a writing state An electronic pen comprising a pen switch for determining whether or not, at least one or more infrared receivers, two or more ultrasonic receivers, and detecting that the infrared signals and the ultrasonic signals have been received An infrared ultrasonic measurement unit having a reception circuit, and a distance between the electronic pen and the ultrasonic reception unit is calculated from a difference in arrival time between the infrared signal and the ultrasonic signal, A handwriting handwriting input system comprising: a coordinate calculation unit that calculates position coordinate data of an electronic pen; and a conversion processing unit that has a function of converting the position coordinate data of the electronic pen into handwriting data. The gist of the signal transmission unit is a handwriting handwriting input system which stops transmission of the infrared signal and the ultrasonic signal for a certain period in response to reception of the infrared signal.

In the handwritten handwriting input system of the present invention, after the infrared receiving unit of the electronic pen receives an infrared signal transmitted from another electronic pen, the infrared ray is transmitted for a certain period shorter than the interval between the infrared signal and the ultrasonic signal being repeatedly transmitted. By stopping the transmission of the signal and the ultrasonic signal, and starting the transmission of the infrared signal and the ultrasonic signal after a certain period of time, there is no interference with the ultrasonic signal of the electronic pen that was in the writing state first. The machine can measure the position coordinates of multiple electronic pens. That is, it is not necessary to register electronic pens used in the receiver in advance, and a plurality of electronic pens can be used.
Therefore, in the handwriting handwriting input system of the present invention, without registering each electronic pen to be used in the receiver in advance, an additional electronic pen can be used during use or changed to another electronic pen. Is possible.

Furthermore, even when the processing capability of the CPU of the receiver is low and processing corresponding to a plurality of electronic pens cannot be performed, the fixed stop period is set to be equal to or longer than the repeated transmission interval of the infrared signal and the ultrasonic signal. In addition, by prohibiting the transmission of infrared signals and ultrasonic signals from other electronic pens, interference can be prevented and at least the handwriting of the electronic pen being written can be accurately input.

The control of the electronic pen is configured to stop transmission for a certain period when an infrared signal transmitted from another electronic pen is received. For example, even if the infrared signal of the electronic pen has an identification number, it is analyzed. There is no need to make the electronic pen perform complicated calculations. That is, it is not necessary to mount a complicated circuit or CPU on the electronic pen, and the handwriting handwriting input system of the present invention can be realized at a relatively low cost.

For example, an infrared transmitter that can transmit infrared signals to the infrared ultrasonic measurement unit of the receiver is provided even when an infrared signal indicating that writing is being sent from an electronic pen is difficult to reach other electronic pens. When the infrared signal transmitted from the electronic pen is received, the infrared signal indicating that the writing is being performed can be transmitted to the other electronic pen more accurately by transmitting from the receiver. This is because the writer usually writes toward the infrared ultrasonic measurement unit of the receiver.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a handwriting handwriting input system according to the invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of a handwritten handwriting input system according to the present embodiment. In the figure, three electronic pens are used, which are an electronic pen 1, an electronic pen 2, and an electronic pen 3, respectively. The receiver 4 includes two ultrasonic receiving units, one infrared receiving unit, an infrared receiving circuit and an ultrasonic receiving circuit, a coordinate calculating unit for calculating position coordinate data of the electronic pen, and position coordinate data. Is composed of components of a conversion processing unit for converting the data into handwriting data. The receiver 4 is connected to the computer 7 via the communication interface 6, and the handwriting data of the electronic pen 1 is transmitted from the conversion processing unit of the receiver 4 to the computer 7. A handwriting can be displayed, a character recognition process can be performed, or it can be stored in a storage device.

  The structure of the electronic pen will be described with reference to the block diagram of the electronic pen in FIG. The basic configuration of the electronic pen includes an ultrasonic transmitter 11 capable of transmitting an ultrasonic signal by the ultrasonic generator 10, an infrared transmitter 9 capable of transmitting an infrared signal by the infrared generator 8, and an ultrasonic wave. A signal transmitting unit 16 for controlling the interval at which the signal and the infrared signal are repeatedly transmitted, an infrared receiving unit 13 for receiving the infrared signal, an infrared measuring unit 17 for detecting the reception of the infrared signal, and a writing unit for the pen tip 15. Pen switch 14 that is turned on / off in response to a writing state and a non-writing state when the writing unit 15 draws a character or a figure while contacting the recording medium 5, and portability, ease of writing The battery 18 supplies power to the entire electronic pen so that the electronic pen can be used in a wireless manner. In the present embodiment, the writing unit 15 is a ballpoint pen or a mechanical pencil provided with a function capable of leaving a locus directly on the recording medium 5. For example, the writing unit 15 has a built-in stylus and the surface of the display Any surface including the above may be used as a writing medium.

An LC resonance circuit unit including a capacitor, a coil, and an ultrasonic generation element 10 is disposed inside the ultrasonic transmission unit 11, and a piezoelectric element is used as the ultrasonic generation element 10. The shape of this piezo element is often cylindrical. This is because it is preferable that the piezo element of the electronic pen transmits an ultrasonic signal uniformly in any direction on the recording medium 5 regardless of the direction in which the writer uses the electronic pen. . In this configuration, the cylindrical piezo element itself also has a resonance frequency. At this time, it is preferable to adjust the configuration of the resonance frequency f ₀ of the LC resonance circuit unit as close as possible to the resonance frequency of the piezoelectric element. The resonance frequency of a piezo element is determined by the characteristics of the piezo film and the diameter of the cylinder, and the ultrasonic wave has a lower attenuation with distance, while the higher the frequency, the higher the coordinate resolution. To determine the resonance frequency. In the case of a handwritten handwriting input system using an electronic pen, the frequency is preferably about several tens of kHz, and around 80 kHz is preferably used.

A transistor or FET and an infrared ray generating element 8 are arranged inside the infrared ray transmitting unit 9 of the electronic pen, and light emission of the infrared ray generating element 8 can be turned on or off by controlling the transistor or FET. At this time, it is preferable to arrange a plurality of the infrared ray generating elements 8 in consideration of the directivity angle so that infrared signals are transmitted in all directions with respect to the cylindrical axis of the electronic pen.

The infrared receiving unit 13 of the electronic pen is provided with the infrared receiving element 12 and receives an infrared signal transmitted from the infrared generating element 8 of the infrared transmitting unit 9 of another electronic pen. For this reason, the wavelength of the infrared receiving element 12 is preferably the same as the wavelength of the infrared generating element 8. In addition, since the direction in which the infrared signal is received cannot be specified, the directivity angle of the infrared receiving element 12 is taken into consideration so that the infrared signal is received in all directions with respect to the cylindrical axis of the electronic pen, It is preferable to place a plurality of such devices at positions where they cannot be received.

The infrared measuring unit 17 of the electronic pen is composed of an amplifier, a filter circuit unit, and a comparator, and detects an infrared signal that has reached the infrared receiving unit 13. A case where an infrared signal is received from another electronic pen will be described. The infrared signal received by the infrared receiving unit 13 of the electronic pen is sent to the infrared measuring unit 17, amplified by an amplifier, and sent to the filter circuit unit. Even when the external noise is received, the filter circuit unit is preferably a filter that allows a signal in the same frequency band as the infrared signal of the electronic pen to pass through so that the external noise portion can be blocked. For example, when the wavelength of the infrared light emitting element 8 of the electronic pen is 940 nm, a band pass filter having a peak at a wavelength of 940 nm may be designed. Thereafter, when the comparator receives a signal that is equal to or greater than a predetermined threshold value, the infrared measurement unit 17 informs the signal transmission unit 16 that the infrared signal has been received. Alternatively, when the electronic pen changes to a writing state, the signal transmission unit 16 may perform control such that the infrared measurement unit 17 confirms whether or not an infrared signal is received from another electronic pen.

When the infrared receiving unit 13 of the electronic pen has not received an infrared signal from another electronic pen, the pen switch 14 is on during the period in which the writing unit 15 of the electronic pen is in contact with the recording medium 5 and is in the writing state. Thus, the signal transmitter 16 can transmit the position coordinates of the electronic pen in the writing state by repeatedly transmitting the infrared signal and the ultrasonic signal at regular intervals. The shorter the constant repetition interval between the infrared signal and the ultrasonic signal, the more accurate handwriting can be expressed. For example, it may be transmitted repeatedly at intervals of 15 ms.

Next, the structure of the receiver 4 will be described with reference to an internal block diagram of the receiver of FIG. The receiver 4 includes an infrared receiver 30, ultrasonic receivers 31 and 32, an amplifier 33, a filter circuit unit 36, a comparator 41, an infrared receiver circuit 54, amplifiers 34 and 39, a filter circuit unit 37, and a comparator 42. An infrared ultrasonic measurement unit 44 having an ultrasonic reception circuit 55 comprising: an amplifier 35, 40, a filter circuit unit 38, and an ultrasonic reception circuit 56 comprising a comparator 43; a CPU 45, a timer 46, a flash memory 47, and a RAM 48. A coordinate calculation unit 49, a conversion processing unit 52 including a CPU 50 and a RAM 51, a communication interface 6 for connecting to the computer 7, and a battery 53 capable of supplying power to the entire receiver 4. It is better to install the ultrasonic receiving circuits 55 and 56 by the number of ultrasonic receiving units so that the ultrasonic receiving units 3 1 and 32 can perform processing even if they simultaneously receive ultrasonic signals. In the present embodiment, the coordinate calculation unit 49 and the conversion processing unit 52 are described separately by function, but the CPU and RAM of the coordinate calculation unit 49 and the conversion processing unit 52 may be common.

The infrared receiving unit 30 of the receiver is configured in the same manner as the infrared receiving unit 13 in the electronic pen, the infrared receiving element is arranged, and is transmitted from the infrared generating element 8 of the infrared transmitting unit 9 of the electronic pen. Receiving infrared signals. The ultrasonic receivers 31 and 32 are configured by the same ultrasonic generator 10 inside the ultrasonic transmitter 11 of the electronic pen, and are transmitted from the ultrasonic generator 10 of the ultrasonic transmitter 11. An ultrasonic signal is received. The receiver 4 is provided with an opening so that an ultrasonic signal transmitted from the electronic pen can be received without being blocked.

The reception of the infrared signal on the receiver side will be described. Similar to the reception of the infrared signal of the electronic pen, the infrared signal received by the infrared receiver 30 is amplified by the amplifier 33, the external noise part is blocked by the filter circuit unit 36, and then a predetermined threshold value by the comparator 41. When the above signal is received, the CPU 45 of the coordinate calculation unit 49 reads the time at that time from the timer 46 when the comparator 41 detects the signal, and this time is stored in the RAM 48 as the arrival time of the infrared signal. save.

Since the ultrasonic receiving circuits 55 and 56 have the same circuit configuration, the ultrasonic receiving unit 31 and the ultrasonic receiving circuit 55 will be described. The ultrasonic reception unit 31 receives the ultrasonic signal, the amplifier 34 amplifies the signal, and sends it to the filter circuit unit 37. Even when the external noise is received, the filter circuit unit 37 is preferably a filter that allows a signal in the same frequency band as the ultrasonic signal transmitted from the electronic pen to pass through so that the external noise portion can be blocked. For example, when the resonance frequency of the electronic pen is 80 kHz, a band pass filter having a peak at a frequency of 80 kHz may be designed. After that, the signal is amplified again by the amplifier 39, so that the rising edge becomes steeper and the head of the signal can be accurately identified. Thereafter, the comparator 42 detects the reception of a signal equal to or greater than a specific threshold value, and transmits a timing signal to the CPU 45 of the coordinate calculation unit 49. When detecting the timing signal sent from the comparators 42 and 43, the CPU 45 of the coordinate calculation unit 49 reads the current time from the timer 46 and stores this time in the RAM 48 as the arrival time of the ultrasonic signal.

The CPU 45 of the coordinate calculation unit 49 arrives at the arrival time of the infrared signal in the infrared reception unit 30 of the receiver stored in the RAM 48 and the arrival time of the ultrasonic signal in the two ultrasonic reception units 31 and 32. The distance from the electronic pen to the ultrasonic receivers 31 and 32 is calculated using the time difference and the sound speed. The position coordinates of the electronic pen are calculated using the theory of the trilateration method, assuming a triangle having the apex of the position of the electronic pen and the two ultrasonic receivers 31 and 32. The CPU 45 stores the calculated position coordinate data of the electronic pen in the RAM 51 of the conversion processing unit 52.

  The CPU 50 of the conversion processing unit 52 recognizes the position coordinate data of the electronic pen stored in the RAM 51 as stroke data of a series of aggregates based on the coordinate acquisition interval. The continuous position coordinate data constituting the stroke data is connected and corrected so as to draw a smooth line, and is transmitted to the computer 7 as handwriting data. In the present embodiment, writing is performed while connected to the computer 7, but the communication interface 6 and the computer 7 are disconnected from the receiver 4, and the receiver 4 uses the power of the battery 53 to connect the computer such as outdoors. Can be used where there is no place. In this case, the position coordinate data may be left in the RAM 51 of the conversion processing unit 52, or the data converted into handwriting data may be left. When the receiver 4 is connected to the computer 7 again, the CPU 50 of the conversion processing unit 52 transmits the data in the RAM 51 to the computer 7.

The transmission timing of the infrared signal and the ultrasonic signal of the electronic pen will be described with reference to the transmission timing chart when the two electronic pens of FIG. 4 are written.
The electronic pens 1 and 2 to be used repeatedly transmit infrared signals and ultrasonic signals at intervals of T1. First, when writing is started with the electronic pen 1, the electronic pen 2 receives an infrared signal from the electronic pen 1 to detect that another electronic pen is writing. For example, when an infrared signal is received at the position a, the electronic pen 2 changes to a writing state within this period as a period (until the position b) during which the transmission of the infrared signal and the ultrasonic signal is stopped within the time T2. However, infrared signals and ultrasonic signals are not transmitted. That is, when the electronic pen 2 changes to the writing state at the position c, the infrared signal and the ultrasonic signal are transmitted at the position b, and when the electronic pen 2 changes to the writing state at the position d, the transmission is stopped during the period during which the transmission is stopped. Since there is not, it transmits at the position of d. However, when the writing state is changed at the position e, the infrared signal of the next electronic pen 1 is overlapped after the time T2 (position f), so that the infrared transmission is stopped at the position g as a period for stopping transmission to the position g. Transmits signals and ultrasonic signals. Thereafter, the electronic pen 2 repeatedly transmits an infrared signal and an ultrasonic signal at an interval of T1, so that the two electronic pens can transmit the position coordinates without interference.

For example, if the writing area of the recording medium 5 is equivalent to A4 paper, the distance farthest from the receiver 4 is about 350 mm, so that the maximum time until arrival at the receiver when the writing electronic pen transmits an ultrasonic signal Is about 1.1 ms, and the ultrasonic signal intensity on the receiver side is attenuated to a negligible value in 3 ms even if the residual amplitude of the ultrasonic waves is taken into consideration. In other words, in an electronic pen that has received an infrared signal indicating that another electronic pen is in a writing state, a period T2 during which transmission of the infrared signal and the ultrasonic signal is stopped is set to 3 ms, so that the receiver has two electronic pens. Can be received without interference.

Also, the start timing of the period T2 during which the transmission of infrared signals and ultrasonic signals of other electronic pens is stopped is set based on the transmission timing of the infrared signals and ultrasonic signals of the electronic pen that has started writing. By doing so, more electronic pens can be transmitted without interference. With reference to the transmission timing chart when the electronic pen 1 in FIG. 5 is used as a reference, the transmission timing of infrared signals and ultrasonic signals from other electronic pens will be described.
First, when writing is started with the electronic pen 1, the electronic pen 2 receives an infrared signal from the electronic pen 1 to detect that another electronic pen is writing. For example, when infrared rays are received at the position h, the interval T1 (up to the position i) informs the signal receiver 16 that another electronic pen is writing. During this time, since no other infrared signal is received, it can be seen that one electronic pen is writing. If the electronic pen 2 is in the writing normal state at the position j, the signal transmission unit 16 transmits the time from the time when the infrared signal of the electronic pen 1 is next detected (position i) to the time T2 (position k). Thereafter, the infrared signal and the ultrasonic signal are repeatedly transmitted at intervals of T1.
By providing such a period for stopping transmission, it is possible to secure a longer period T3 for preventing interference when an electronic pen is further added. For example, when the transmission interval T1 between the infrared signal and the ultrasonic signal is set to 15 ms and the period T2 during which transmission is stopped is set to 3 ms, a maximum of five electronic pens can be transmitted without interference.

Next, the reception timing of the infrared signal and the ultrasonic signal will be described with reference to the reception timing chart when writing with two electronic pens in FIG.
The coordinate calculation unit 49 of the receiver 4 calculates the position coordinates of the first electronic pen from the arrival time difference P1 when the infrared signal is first received (position l) and when the ultrasonic signal is received (position m). To do. After that, when the arrival time difference T4 between the received infrared signal (position n) and the position l is T1 time or less, the second received infrared signal is determined to be an infrared signal transmitted from a different electronic pen. Then, the arrival time difference P2 from the next received ultrasonic signal (position of o) is calculated as the position coordinate of the second electronic pen. Since the next received infrared signal (position q) is received after T1 time from the position l, it is determined as the first received infrared signal from the electronic pen, and the arrival time difference P3 is set as the first electronic pen. Calculated as the position coordinates. Next, since the received infrared signal (position r) is received after T1 time from the position n, P4 is calculated as the position coordinate of the second electronic pen. By repeating this, the position coordinates of the two electronic pens can be measured.

In the handwriting handwriting input system according to the present invention, theoretically, when two electronic pens are in a writing state at the same time, that is, after one electronic pen is in a writing state, the other is transmitted. When the electronic pen is in a writing state, an infrared signal and an ultrasonic signal are transmitted from the two electronic pens to cause interference, but this time is several tens depending on the circuit configuration of the electronic pen. Since it can be shortened to about μS, it is considered that the electronic pen of the present invention is not in a writing state at the same time.

Using the transmission timing chart when writing three electronic pens in FIG. 7, the infrared signal and the ultrasonic signal of the electronic pen 1 and the electronic pen 2 when the electronic pen 3 is added and written. The transmission timing will be described. At this time, it is assumed that other pens are transmitted based on the transmission of the electronic pen 1 which has started writing.
For example, when the electronic pen 3 receives the infrared signal of the electronic pen 1 at the position s, the interval T1 (up to the position u) informs the signal receiving unit 16 that another electronic pen is writing. Since the infrared signal is received again T2 hours after the position s (position v), it can be seen that two electronic pens are being written. Assuming that the electronic pen 3 is in a writing normal state at the position w, the signal transmission unit 16 also T2 hours after the time when the infrared signal of the electronic pen 1 is detected (up to the position u) (x position). Since it can be predicted that an infrared signal will be received, interference will be prevented by repeatedly transmitting the infrared signal and the ultrasonic signal at intervals of T1 after a period of T2 (y position) after which transmission is stopped. The position coordinates of the three electronic pens can be transmitted.
Further, when the timing at which the electronic pen 3 receives the infrared signals of the other two electronic pens is shifted and the infrared signal of the electronic pen 2 is received before the infrared signal of the electronic pen 1, that is, s cannot be detected. Even if v is detected in the signal, since the infrared signal is not received after T2 time (z position), the signal transmitting unit 16 receives the infrared signal of the next electronic pen 2 (from the x position). By transmitting the infrared signal and the ultrasonic signal as the period for stopping the transmission until the time T2 (position y), the infrared signal of the electronic pen 1 is transmitted at the same timing as when it was first received. Become.
Even when there are three electronic pens, the coordinate calculation unit 49 of the receiver 4 recognizes an infrared signal of the same electronic pen that is at the T1 interval from when the first infrared signal is received, as in the case of two electronic pens. However, infrared signals received at intervals less than that may be calculated by recognizing a different electronic pen.

For example, when writing of the electronic pen 2 is completed while writing with three electronic pens, the transmission timing of the electronic pen 1 and the electronic pen 3 is not changed, only the infrared signal and the ultrasonic signal of the electronic pen 2 are not transmitted. . Further, when the electronic pen 1 and the electronic pen 3 write the electronic pen 2 again while writing, the transmission timing of the electronic pen 2 changes depending on which electronic pen receives the infrared signal first. That is, if the infrared signal of the electronic pen 1 is received first, the infrared signal and the ultrasonic signal are transmitted T2 hours later, and if the infrared signal of the electronic pen 3 is received first, the infrared signal is transmitted T2 hours later. And send out ultrasonic signals.

  For example, when an identification number for identifying an electronic pen is placed on an infrared signal, an ultrasonic signal, or the like, the infrared ultrasonic measurement unit 44 of the receiver 4 can specify which electronic pen the signal is transmitted from. The handwriting data can be displayed separately for each, or the color can be changed for each electronic pen.

Next, the case where there is an infrared transmitter 57 that can transmit an infrared signal to the infrared ultrasonic measurement unit 44 of the receiver 4 will be described using the block diagram of the receiver having the infrared transmitter of FIG. To do. The inside of the infrared transmission unit 57 is configured by the same as the infrared transmission unit 11 in the electronic pen. When the comparator 41 detects an infrared signal, it transmits an infrared signal having the same wavelength as the infrared signal received from the infrared transmitter 57. At this time, since the electronic pen that has started writing also receives the infrared signal from the infrared transmitter 57, control is performed so that this signal is ignored. In this way, for example, even when an infrared signal indicating that writing is being sent from an electronic pen is hidden behind the hand and difficult to reach other electronic pens, the writer usually writes toward the infrared ultrasonic measurement unit of the receiver. Therefore, it is possible to more accurately transmit an infrared signal indicating that writing is being performed to another electronic pen.

Example 1
Hereinafter, the present invention will be described with reference to examples and comparative examples. The present invention is not limited to the following examples, and includes various modifications within the technical scope of the present invention.
In Example 1, the handwriting handwriting input system which has arrange | positioned three electronic pens of the electronic pen 1, the electronic pen 2, and the electronic pen 3 like FIG. 1 was used. However, the resonance frequency of the ultrasonic transmission unit 11 of the electronic pen is set to 80 kHz, the repetitive transmission interval between the infrared signal and the ultrasonic signal of the signal transmission unit 16 is 15 ms, and the transmission is stopped when the writing state overlaps. It was set to be 3 ms. The filter circuit unit in the electronic pen and the filter circuit unit 36 in the receiver are band-pass filters having a peak at 940 nm. Similarly, the filter circuits 37 and 38 in the receiver are band-pass filters having a peak at 80 kHz. While the receiver 4 was connected to the computer, writing was performed while displaying the handwriting on the computer screen.

(Example 2)
The handwriting handwriting input system which arrange | positioned three electronic pens similarly to Example 1 was used. At this time, as shown in FIG. 8, an infrared transmitter 57 capable of transmitting an infrared signal to the infrared ultrasonic measurement unit 44 of the receiver 4 was disposed. However, the resonance frequency of the ultrasonic transmission unit 11 of the electronic pen is set to 80 kHz, the repetitive transmission interval between the infrared signal and the ultrasonic signal of the signal transmission unit 16 is 15 ms, and the transmission is stopped when the writing state overlaps. It was set to be 3 ms. The filter circuit unit in the electronic pen and the filter circuit unit 36 in the receiver are band-pass filters having a peak at 940 nm. Similarly, the filter circuits 37 and 38 in the receiver are band-pass filters having a peak at 80 kHz. While the receiver 4 was connected to the computer, writing was performed while displaying the handwriting on the computer screen.

(Comparative Example 1)
The handwriting handwriting input system which arrange | positioned three electronic pens similarly to Example 1 was used. However, it is assumed that the infrared pen 13 and the infrared measuring unit 17 do not exist in the electronic pen.
In addition, the resonance frequency of the ultrasonic transmission unit 11 of the electronic pen was set to 80 kHz, and the transmission interval of the ultrasonic signal of the signal transmission unit 16 was set to 15 ms. The filter circuit unit in the electronic pen and the filter circuit unit 36 in the receiver are band-pass filters having a peak at 940 nm. Similarly, the filter circuits 37 and 38 in the receiver are band-pass filters having a peak at 80 kHz. The receiver 4 connected to the computer and performed writing while displaying the handwriting on the computer screen.

(Comparative Example 2)
In the handwriting handwriting input system composed of three electronic pens and a receiver, the identification numbers of the electronic pen 1, electronic pen 2, and electronic pen 3 to be used are registered in advance in the receiver. The receiver transmits an infrared signal including an identification signal, the electronic pen verifies the received identification signal, and transmits an ultrasonic signal at its own identification number. We used a handwriting handwriting input system that can measure the position coordinates. However, the repetition transmission interval of the infrared signal of the receiver was set to 15 ms, and the time allocated to one electronic pen was set to 3 ms. While the receiver was connected to the computer, writing was performed while displaying the handwriting on the computer screen.

The handwritten handwriting input systems of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were evaluated on the following items, respectively.
(1) When the electronic pen 2 and / or the electronic pen 3 are in a writing state during writing of the electronic pen 1, the receivers of Example 1, Example 2, and Comparative Example 2 are not affected by the electronic pen 1 being written. However, in Comparative Example 1, there was interference of ultrasonic signals in the receiver, and there were portions where the handwriting of the electronic pen 1 could be left normally and portions where the handwriting did not become.
(2) When the electronic pen 1 was replaced with another electronic pen 4 in use, Example 1, Example 2, and Comparative Example 1 were able to replace the electronic pen without any problem. In Example 2, since the electronic pen to be replaced needs to be registered in the receiver in advance, the handwriting of the replaced electronic pen could not be left.
(3) When the electronic pen 2 and the electronic pen 3 are in a writing state while the electronic pen 1 is being written, the receivers of the example 1, the example 2, and the comparative example 2 input the handwriting of the three electronic pens without any problem. Although it was possible, the receiver of Comparative Example 1 was unable to leave the handwriting of all three electronic pens.
(4) When writing with the electronic pen 1, the electronic pen 2, and the electronic pen 3 and adding one electronic pen 5 and writing with the four electronic pens, the receivers of the first and second embodiments are problematic. The handwriting of four electronic pens could be input, but the receiver of Comparative Example 2 needs to register the electronic pen 5 to be added in advance in the receiver. could not.
Table 1 summarizes the above evaluation results.

In a handwriting input system that calculates the position coordinates of a plurality of electronic pens, a high-speed CPU is required for the receiver. In particular, in Comparative Example 2, a high-speed CPU is required for each electronic pen in order to analyze the identification signal, which is disadvantageous if an expensive system is used. On the other hand, in the first and second embodiments of the present invention, a high-speed CPU may be used only for the receiver 4.

However, as a method of using a low-speed CPU for the receiver 4 and preventing at least interference and accurately inputting the handwriting of the electronic pen during writing, for example, a period during which transmission is stopped is set as a repetition transmission interval between an infrared signal and an ultrasonic signal. If the same or longer time is set, the electronic pen that started writing later will not transmit infrared signals and ultrasonic signals, so it will repeatedly transmit infrared signals and ultrasonic signals within the handwriting input system. Although only one electronic pen is used and handwriting of a plurality of electronic pens cannot be input at one time, at least interference can be prevented and the handwriting of the electronic pen being written can be input accurately.
For example, the same as in the first embodiment except that the repetition transmission interval of the infrared signal and the ultrasonic signal of the signal transmission unit 16 of the electronic pen is set to 15 ms, and the period for stopping transmission when the writing state overlaps is set to 15 ms. In addition, when the electronic pen 2 and / or the electronic pen 3 is in a writing state during writing of the electronic pen 1 using a handwriting handwriting input system in which three electronic pens are arranged, the receiver is writing without any problem. I was able to leave the handwriting of the electronic pen 1.

In this case, the electronic pen is provided with an LED, a vibration motor, etc., and during the period when the electronic pen stops transmitting, it is used to inform the writer that the infrared signal and the ultrasonic signal are not transmitted. Good.

Perspective view of handwriting handwriting input system Electronic pen block diagram Internal block diagram of the receiver Transmission timing chart when writing with two electronic pens Transmission timing chart when the electronic pen 1 is used as a reference Reception timing chart when writing with two electronic pens Transmission timing chart when writing with three electronic pens Block diagram of a receiver having an infrared transmitter

Explanation of symbols

1, 2, 3 Electronic pen 4 Receiver 5 Recording medium 6 Communication interface 7 Computer 8 Infrared generator 9 Infrared transmitter of electronic pen 10 Ultrasonic generator 11 Ultrasonic transmitter 12 Infrared receiver 13 Infrared receiver of electronic pen Part 14 Pen switch 15 Writing part 16 Signal sending part 17 Infrared measuring part 18, 53 Battery 30 Infrared receiving part 31, 32 of receiver Ultrasonic receiving part 33, 34, 35, 39, 40 Amplifier 36, 37, 38 Filter circuit 41, 42, 43 Comparator 44 Infrared ultrasonic measurement unit 45, 50 CPU
46 Timer 47 Flash memory 48, 51 RAM
49 Coordinate operation unit 52 Conversion processing unit 54 Infrared receiving circuit 55, 56 Ultrasonic wave receiving circuit 57 Infrared transmitter of receiver

Claims (2)

A signal transmitter having at least an infrared transmitter including an infrared generator and an ultrasonic transmitter including an ultrasonic generator, and repeatedly transmitting an infrared signal and an ultrasonic signal from the infrared transmitter and the ultrasonic transmitter And an infrared measuring unit having an infrared receiving unit including an infrared receiving element, a writing unit having a function capable of leaving a locus directly on a recording medium, and whether or not the writing unit is in a writing state An electronic pen comprising a pen switch, at least one or more infrared receivers, two or more ultrasonic receivers, and a receiving circuit for detecting that the infrared signals and the ultrasonic signals have been received. An infrared ultrasonic measurement unit, and a distance between the electronic pen and the ultrasonic reception unit is calculated from an arrival time difference between the infrared signal and the ultrasonic signal, and the electronic pen is calculated using the distance A handwriting handwriting input system comprising a coordinate calculation unit for calculating position coordinate data, and a conversion processing unit having a function of converting the position coordinate data of the electronic pen into handwriting data, wherein the signal transmission unit of the electronic pen Is a handwriting handwriting input system which stops transmission of infrared signals and ultrasonic signals for a certain period in response to reception of infrared signals The handwritten handwriting input system according to claim 1, wherein the infrared ultrasonic measurement unit includes an infrared transmission unit.

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