JPH06309084A - Optical coordinate input device - Google Patents

Abstract

PURPOSE:To simplify the structure of a passive digital tablet by forming the tablet of an array of patterns on an M plane including coordinate. information, partially reading out a pattern at a position specified with a stylus pen, and finding the two-dimensional coordinates of the position commanded on the basis of the read pattern image. CONSTITUTION:A pattern drawn on the top surface 18a of the tablet 18 utilizes a two-dimensional series called the M plane. When the top surface of the tablet 18 is specified with the stylus pen 1 and a side switch 11 is turned ON, an oscillator 8 oscillates and the output of the oscillator is modulated on the basis of an image pattern represented with part of a pattern corresponding to the specified position projected on the photodetection surface 17 of a photodetecting element 9. AN electromagnetic wave radiated by a transmitting coil 3 through the oscillation is received by a receiving coil 25 and inputted to a demodulator 26. The demodulator 26 extracts the image pattern and a coordinate information extracting means 27 extracts coordinate information from a signal representing the image pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coordinate input device, and more particularly to a stylus pen having a coordinate information reading device including an optical system and a light receiving section, and a passive digital device having a pattern containing two-dimensional coordinate information. The present invention relates to an optical coordinate input device that is configured with a tablet and that enables handwriting input on the surface of the tablet.

[0002]

2. Description of the Related Art As a conventional optical coordinate input device, an optical digitizer disclosed in JP-A-61-43328 (Japanese Patent Publication No. 2-18722), a stylus locator disclosed in JP-A-3-37707, and There is a data entry system.

In the former optical digitizer, when a figure drawn on paper is read and input, a transparent plate on which an M-series lattice pattern is drawn is arranged on the paper, and a two-dimensional CCD element or the like is used. It is configured so that the cursor with the built-in optical reader is placed on the transparent plate, and when the cursor is traced on the transparent plate and the position of each part of the pattern is designated by the cursor, the pattern The coordinates of the specified position are obtained by reading a part with an optical reading device, and the figure can be read by this.

The latter stylus locator and data entry system comprises a tablet and an optical stylus that optically scans the coordinate values of any position on the XY coordinate plane that is scanned on the tablet and defined by the tablet surface. The tablet is a passive digitizing tablet, and a photodetectable pattern (tablet address cell) including a binary code indicating coordinate information of a two-dimensional coordinate plane is recorded on the surface of the tablet. In addition, the optical stylus has a built-in light source for illumination, an optical system, and a light receiving element. When the position on the tablet surface is specified by the optical stylus, the binary code by the tablet address cell is read, and the special computer specifies the optical stylus. The coordinates of the position that has been determined are determined.

[0005]

Problems to be Solved by the Invention JP-A-63-1332
In the optical digitizer disclosed in No. 8, the position indicator has a cursor type and a coded structure, and the cursor type position indicator has an illumination light source inside and a plurality of optical filters are used for irradiation. The frequency of the light used for reflection is set to a predetermined value. Therefore, the structure is complicated and the manufacturing cost is high. Although the embodiment uses a lattice pattern in which one-dimensional M-sequences are orthogonalized, a large number of light-receiving element cells are required, and the coordinate detection process becomes complicated and expensive.

In the stylus locator and data entry system disclosed in Japanese Patent Laid-Open No. 3-37707, the photodetectable pattern recorded on the surface of the passive digitizing tablet is formed by a plurality of discrete cells of tablet address cells, Moreover, in order to read the coordinate position by the optical stylus, it is necessary to include at least one tablet address cell in the visual field of the light receiving element, so that a large number of cells are required and the apparatus becomes expensive.

An object of the present invention is to provide an optical coordinate input device having a passive digitizing tablet having a simple structure, which can be manufactured at low cost and is highly economical.

[0008]

The optical coordinate input device according to the present invention provides a tablet on which a pattern having a sequence of M planes including two-dimensional coordinate information is recorded, and an instruction is given on the tablet surface. An optical device for optically reading a part of the pattern corresponding to a position and a position indicator including a signal generating means for generating a signal for the part of the pattern read by the optical device, and a part of the pattern Coordinate information extracting means for receiving a signal, assigning a numerical value corresponding to a pattern feature obtained from this signal, and extracting the two-dimensional coordinate information of the position indicated by the position indicator using the magnitude relation of the assigned numerical values. Composed of and. In such a configuration, preferably, the pattern having an array of M planes is a dot pattern composed of digitally encoded large and small dots.

In the above arrangement, preferably, the coordinate information extracting means allocates a large numerical value to a large dot and a small numerical value to a small dot, a means for expanding an image space related to the allocated numerical value, and an image related to the numerical value. Means for applying a smoothing operator to the space to smooth the numerical values, means for selecting a large numerical value from the numerical values contained in the image space relating to the smoothed numerical values to create a peak table, and for example, 4 included in the peak table. It includes means for generating a coordinate code using two numerical values.

In the above structure, preferably, the position indicator has a transmitting unit for transmitting a signal relating to the part of the pattern read by the optical device, and the tablet has a receiving unit for receiving the signal.

In the above structure, preferably, the transmitting unit includes a modulator and the receiving unit includes a demodulator. Further, the receiving section is characterized by including a receiving coil provided around the surface of the tablet.

[0012]

According to the present invention, a tablet having a simple structure is formed by using a passive digitizing tablet having a pattern of fine dots, for example, large and small dots, having a characteristic of arranging M planes on the surface, and a tablet having a simple structure is formed. Coordinates are input by designating a position by using an optical position indicator having an optical device having a function of partially reading the pattern and a signal generation unit for generating a signal including the read pattern information. be able to. In this coordinate input, the coordinate information extracting means extracts the coordinate code included in the partial pattern based on the information of the partial pattern read by the optical device. The process for coordinate code extraction executed by the coordinate information extraction means is a calculation process for uniquely calculating coordinates on the tablet surface. In this way, the coordinate code for obtaining the coordinate position of the position is extracted based on the partial pattern information corresponding to the position designated by the position indicator on the tablet surface, and the two-dimensional coordinate corresponding to the coordinate code is extracted. It is possible to obtain. In addition, the position indicator is equipped with a transmitting unit, and by the modulation and resonance transmitting action, a part of the read pattern information is given to the receiving unit on the tablet side, and in this transmission a characteristic receiving antenna is used. An electromagnetic wave having a relatively low frequency and not having high directivity can be used.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view showing the internal structure of the stylus pen. Inside the stylus pen, an optical device, a modulator, an oscillator, a transmitter, and the like are provided as a configuration of an input unit (pen type position indicator) of the pen input computer. Here, the “optical device” includes a light guide optical system and a light receiving element, and reads a pattern image for partially reading a pattern including two-dimensional coordinate information recorded by drawing or the like on the surface of a tablet described later. Means a vessel.

The structure of the stylus pen 1 will be described. The stylus pen 1 comprises a transmitter coil 3 in the tip of a pen housing 2. The transmission coil 3 is an inductance element of a resonance circuit described later and has a transmission function. The transmission coil 3 has a ferrite core 4 in its inner space, and the transmission coil 3 is wound around the ferrite core 4. A hole is formed in the shaft portion of the ferrite core 4, and the core body 5 is disposed in the hole in a state of being inserted. The core body 5 advances or retracts in the axial direction in the inserted state. The tip of the core body 5 projects outward from the tip of the pen, and when the tip of the stylus pen 1 is brought into contact with the surface of the position coordinate tablet, it has a function of transmitting the writing pressure to the writing pressure detection device 6. Therefore, the core body 5 functions as a writing pressure transmission means. The writing pressure detection device 6 detects the transmitted writing pressure and applies a detection signal to the oscillator 8 on the circuit printed board 7. The oscillator 8 includes a resonance circuit that uses the transmission coil 3 as an inductance element, and has a circuit configuration that changes the oscillation frequency of the resonance circuit, for example, when a detection signal is given from the writing pressure detection device 6. The circuit printed board 7 is further provided with a light receiving element 9 such as a CCD area sensor, a modulator 10 and a side switch 11. The stylus pen 1 functions as a cordless stylus pen by the oscillator 8 and the transmission coil. The side switch 11 extends outside the pen housing 2. A power source 12 such as a battery is arranged behind the circuit printed board 7 to supply electric power to each circuit portion on the circuit printed board 7.

Next, the structure of the optical device will be described. A light guide path housing 13 for forming a light guide path (light path) is integrally formed with the pen housing 2 on the upper front side of the pen housing 2. Inside the light guide path housing 13, a tendency prism 14 is provided at the window at the front end, a condenser lens 15 is provided at a required position in the center, and a reflector 16 is provided at the back. A light receiving element 9 having a light receiving surface (field of view) 17 is provided at a position above the printed circuit board 7 below the reflection plate 16. The light receiving surface 17 is formed by a large number of pixels arranged in a plane (two-dimensional). A window for taking in external light (light from the outside) formed by the trend prism 14 is formed in the front part of the light guide housing 13 at the tip of the stylus pen 1. External light entering from the tip of the pen through the window is guided in the longitudinal direction of the light guide path by the trend prism 14, condensed by the condenser lens 15, reflected by the reflector 16 and enters the light receiving surface 17 of the light receiving element 9. . The light received by the light receiving element 9 is output as an electric signal proportional to the light intensity based on the photoelectric conversion action of each pixel. The output signal of the light receiving element 9 is given to the modulator 10. In the above-mentioned configuration, external light is taken in, but it is also possible to provide a light source for illumination inside and give irradiation light to the tablet surface to take in reflected light.

In FIG. 1, 18 is a tablet arranged in front of the tip of the stylus pen 1. Tablet 1
8 is a passive digitizing tablet which itself does not positively act on the stylus pen 1. A predetermined pattern is recorded by drawing or the like on the surface of the tablet 18 facing the tip of the stylus pen 1. This pattern is a pattern having an array of M planes, and is a dot pattern including information on two-dimensional (XY) coordinates that determine an absolute position on the surface of the tablet 18. When the stylus pen 1 is brought close to the surface of the tablet 18, the light receiving surface 1 of the light receiving element 9 is passed through the window (trend prism 14) at the tip thereof.
It is possible to project an image of a part of the pattern on 7. Part of the pattern detected by the light receiving surface 17 of the light receiving element 9 represents a code relating to the coordinates of the position designated by the stylus pen 1 on the tablet surface, and the two-dimensional position coordinates can be obtained by this coordinate code. Reference numeral 19 denotes a locus along which the light rays coming from the surface of the tablet 18 are guided to the light receiving surface 17 of the light receiving element 9.

As shown in FIG. 2, the pattern image detected on the light receiving surface 17 which is the visual field of the light receiving element 9 is output as an electric signal by the photoelectric conversion action of each pixel and supplied to the modulator 10. The modulator 10 changes the oscillation output (oscillation frequency, amplitude, etc.) set by the oscillator 8 of the next stage by the output signal. The output signal of the modulator 10 includes the information (dot information) about the inputted pattern image, so that the output signal of the oscillator 8 is modulated based on the information about the pattern image detected by the light receiving element 9. Become. At the output of the oscillator 8, a signal relating to the pattern image detected by the light receiving element 9 is generated. In the above embodiment, the configuration for generating a signal in the case of a cordless styleless pen has been described, but in the case of a corded styleless pen, an oscillator and a modulator are not required, and a signal sending unit of any format can Is a means for generating.

The image on the light-receiving surface 17 of the light-receiving element 9 is generally an image of visible light, but an infrared-pass filter may be provided in front of the light-receiving surface 17 so that only infrared light is utilized. it can. According to the configuration using infrared rays, the disturbance can be removed and the pattern image can be accurately obtained.

Transmitting coil 3 wound around ferrite core 4
Is used as an inductance element forming a resonance circuit as described above, and the detection signal of the writing pressure detection device 6 is supplied to the modulator 10 and the power supply controller 21. Reference numeral 11 is a side switch, and the signal generated by the ON operation is the modulator 1
0 and the power supply controller 21. In this way, the writing pressure information and the ON operation information are included in the oscillation signal via the modulator 10. 12 is a power supply. When the writing pressure detection device 6 detects writing pressure, or when the side switch 11 is turned on, driving power is supplied from the power supply 12 to the modulator 10 and the oscillator 8 via the power supply controller 21, and the modulator 10 is supplied. Then, the oscillator 8 is activated and the modulator 10 is provided with operation information. An oscillation signal is output from an oscillator 8 including a resonance circuit composed of the transmission coil 3 and a capacitor (not shown). An electromagnetic wave having a relatively low frequency is generated in the surrounding space by this oscillation signal. The electromagnetic wave output from the transmission coil 3 to the surrounding space is modulated by amplitude modulation or the like by the modulation signal output from the modulator 10, and information on the pattern image detected by the light receiving surface (field of view) 17 of the light receiving element 9. Is included. As described below,
According to the pattern drawn on the surface of the tablet 18, since each part includes the coordinate information of the position corresponding to each part, the electromagnetic wave output from the transmission coil 3 includes a portion specified by the stylus pen 1. The coordinate information of is included.

FIG. 3 shows a configuration and a circuit configuration on the tablet 18 side. The tablet 18 has a rectangular upper plane 18a, a two-dimensional coordinate plane is defined on the upper surface 18a, and the stylus pen 1 is used to specify an arbitrary position on the surface 18a to obtain the coordinates of the specified position. ing.
A pattern is drawn on the surface 18a. FIG. 4 is an enlarged view of a part of the pattern. This pattern uses a two-dimensional series called an M plane. Regarding the M-plane, he is familiar with Hiroshi Miyagawa, Yoshihiro Iwadari and Hideki Imai, 1973, "Code Theory" published by Shokodo. The pattern formed by the arrangement of the M planes is, for example, a digitally coded dot pattern formed by fine small circles (dots) and large circles (dots). A square 24 shown by a broken line in FIG. 4 corresponds to a field of view of the light receiving element 9, that is, a region of the light receiving surface 17. In the example shown in FIG. 4, three large circles and one small circle are in the visual field of the light receiving element 9. The illustrated pattern on the M plane has a characteristic that partial patterns of 2 × 2 circles do not overlap. Therefore, the coordinates of the position on the tablet surface where the partial pattern exists can be obtained based on the 2 × 2 partial pattern. The circle that draws the pattern is extremely small,
The resolution of XY coordinates on the tablet surface is determined based on the size. In the illustrated example, the number of dots is reduced for convenience of description, but in practice, for example,
In order to obtain a resolution of 0.5 mm without performing dot-to-dot correction on a 2.5 cm square coordinate reading surface, 250 × 250 dots are required, and to obtain an arbitrary address. Needs to read 4 × 4 dots. The number of pixels of the light receiving element at this time is 32 × 32
The degree is appropriate, and a resolution of 0.1 mm can be obtained by performing interpolation calculation.

A receiving coil 25 is provided around the surface of the tablet 18. Designate an appropriate position with the stylus pen 1 on the surface of the tablet 18 and use the side switch 11
When is turned on, the oscillator 8 oscillates and
The light receiving surface 17 of the light receiving element 9 is formed by the modulator 10 and the oscillator 8.
The output of the oscillator is modulated based on the image pattern (including the coordinate code) represented by a part of the pattern corresponding to the designated position shown in FIG. The electromagnetic wave 28 radiated from the transmitting coil 3 based on the oscillation action is received by the receiving coil 25. The electromagnetic wave received by the receiving coil 25 includes the image pattern described above, and as a result, the coordinate code. The output signal including the image pattern of the receiving coil 25 is input to the demodulator 26. The demodulator 26 is the receiving coil 2
An image pattern is extracted from the output signals of 5. The demodulator 26 also extracts the writing pressure information and the side switch information.
The signal representing the image pattern of the demodulator 26 is supplied to the coordinate information extracting means 27, where the coordinate code, that is, the coordinate information is extracted from the signal representing the image pattern. The position coordinates on the two-dimensional surface 18a of the tablet 18 can be uniquely determined based on the extracted coordinate code. The coordinate code (coordinate information) extracted by the coordinate information extracting means 27 is supplied to the information processing device 29, and the writing pressure information and the side switch information extracted by the demodulator 26 are also supplied to the information processing device 29. It

Next, with reference to FIG. 5 to FIG. 11, a calculation method for extracting the coordinate code in the coordinate information extraction means 27 based on the pattern image detected on the light receiving surface 17 of the light receiving element 9 will be described. . The description will be given according to the flowchart of FIG.

In FIG. 5, the region indicated by the broken line represents the light receiving surface 17 of the light receiving element 9. It is assumed that an image of a part of a pattern formed by a plurality of large circles and small circles is projected onto the light receiving surface 17 shown by a broken line in the illustrated state. For convenience of description, a part of this pattern is provided on the light receiving surface 17
It shows the inside and the outside. A number is written in a broken-line rectangular area representing the light receiving surface 17 corresponding to the pattern image in the light receiving surface 17. A numerical value having a relatively large value is written in a portion corresponding to the large circle, and a numerical value having a relatively small value is written in a portion corresponding to the small circle. Each of the numerical values corresponds to one pixel, and the magnitude of the value is the level of the output signal corresponding to the detected image. As is clear from the description of the numbers in the broken-line rectangular area representing the light receiving surface 17, in the description of this embodiment, the pixel array of the light receiving surface 17 of the light receiving element 9 is formed by 9 × 9 pixels. Information on the pattern image of the light receiving surface 17 shown in FIG. 5 (9 × 9
(Pixel information represented by individual numerical values) is sent to the coordinate information extracting means 27 through the modulator 10, the oscillator 8, the transmitting coil 3, the receiving coil 25, and the demodulator 26. The coordinate information extraction means 27 extracts a coordinate code based on the information of the pattern image according to the flowchart shown in FIG.

Under the above technical premise, step S1 shown in FIG. 11 is executed to read the 9 × 9 pixel information and store the numerical value of each pixel in the buffer memory BUF (18 × 18). At this time, the number of storage locations has increased fourfold, so
The same numerical value is stored in four pixel array elements adjacent to each other. In this way, the BUF (18 × 1
The storage state of 8) is shown in FIG. As is apparent from FIG. 6, the pattern image (numerical image) of the light receiving surface 17 of the light receiving element 9 is magnified 4 times, for example. Then, using an appropriate smoothing operator as shown in FIG. 7, BUF (18 × 1
The stored contents of 8) are subjected to superposition integration and smoothing is executed (step S2). As a result, BUF (18 × 1
The storage state of the numerical values in 8) is as shown in FIG.
In the next step S3, B having the numerical value storage state of FIG.
In the UF (18 × 18), the element having the largest numerical value (top element) is searched for, the address and the numerical value are written in the top table, and then the value of the element and the elements in the vicinity thereof are set to 0. Then search again for the element with the highest number and repeat the process. This operation is repeated until all the elements become 0. FIG. 9 shows the data state of the top elements written in the top table, and FIG. 10 shows the position (address) and the numerical value of each top element written in the top table as BUF (18 × 1).
It is shown on the plane of 8). In the top table shown in FIG. 9, four top elements whose addresses are closest to the center of the light-receiving surface 17 of the light-receiving element 9 (the point at which coordinates are (8.5, 8.5)) are selected (step S4). This 4
The four crest elements are indicated by circled numbers in FIG. If the numerical values of the four elements are, for example, 40 or more, "1" is assigned, and if, for example, 39 or less, "0" is assigned. Generate a coordinate code by. In this way, the coordinate code can be extracted.

Each step executed by the coordinate information extracting means described in FIG. 11 is realized by a microcomputer as a function realizing means.

Although the coordinate input device having the pen type position indicator has been described in the above embodiment, the present invention can also be applied to a cursor type position indicator. A method for extracting a coordinate code from a part of a pattern having an array of M planes is shown in FIG.
It is not limited to the method shown in.

[0028]

As is apparent from the above description, according to the present invention, a tablet is formed by utilizing a pattern of M planes formed so as to include coordinate information, while a stylus pen is used. Since the pattern at the designated position is partially read and the two-dimensional coordinates of the commanded position are obtained based on the read pattern image, the configuration of the coordinate input device is simplified and can be manufactured at low cost. It is possible to improve economic efficiency. In addition, since the transmitting unit in the position indicator and the receiving antenna arranged around the tablet surface are used for exchanging signals between the position indicator and the tablet side, electromagnetic waves with a relatively low frequency and weak directivity are generated. Can be done using.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the internal structure of a stylus pen of an optical coordinate input device according to the present invention.

FIG. 2 is a circuit diagram showing a configuration of an electric circuit provided inside a stylus pen.

FIG. 3 is a circuit diagram showing an electrical configuration provided on the tablet side.

FIG. 4 is a diagram showing a part of a dot pattern showing a series of M planes.

FIG. 5 is a diagram showing a numerical image of a pattern image captured by a light receiving surface of a light receiving element.

FIG. 6 is a diagram in which a numerical image is magnified four times.

FIG. 7 is a diagram showing an example of a numerical pattern of a smoothing operator.

FIG. 8 is a numerical image obtained by smoothing the numerical image shown in FIG. 6 with a smoothing operator.

FIG. 9 is a diagram showing data contents of a top table.

FIG. 10 is a diagram showing a plane in which the elements stored in the top table are arranged.

FIG. 11 is a flowchart illustrating a process of extracting a coordinate code from a read pattern image.

[Explanation of symbols]

 1 Stylus Pen 2 Pen Housing 3 Transmission Coil 4 Ferrite Core 6 Writing Pressure Detection Device 8 Oscillator 9 Light-Receiving Element 10 Modulator 11 Side Switch 13 Light Guide Housing 14 Trend Prism 16 Reflector 17 Light-Receiving Surface 18 Tablet 25 Receiving Coil 26 Demodulator 27 Coordinate information extraction means

Claims (6)

[Claims] 1. A tablet in which a pattern having an array of M planes including two-dimensional coordinate information is recorded on a surface, and an optical for optically reading a part of the pattern corresponding to a position indicated on the surface of the tablet. Pointing device including a signal generating means for generating a signal relating to the partial pattern read by the optical device and the optical device, and a pattern feature obtained from the signal for receiving the signal relating to the partial pattern A coordinate information extracting unit that assigns numerical values corresponding to each other and extracts the two-dimensional coordinate information of the position designated by the position indicator by using the magnitude relation of the assigned numerical values. Input device. 2. The optical coordinate input device according to claim 1, wherein the pattern having the array of M planes is a dot pattern composed of digitally encoded large and small dots. . 3. The optical coordinate input device according to claim 2, wherein the coordinate information extraction means allocates a large numerical value to the large dot and a small numerical value to the small dot, and an image relating to the allocated numerical value. Means for expanding the space, means for smoothing the numerical value by applying a smoothing operator to the image space related to the numerical value, and selecting a large numerical value from the numerical values included in the image space related to the smoothed numerical value. An optical coordinate input device comprising: means for creating a top table; and means for generating a coordinate code using the numerical values included in the top table. 4. The optical coordinate input device according to claim 1, wherein the position indicator has a transmission unit that transmits a signal regarding the part of the pattern read by the optical device, and the tablet is the An optical coordinate input device having a receiving unit for receiving a signal. 5. The optical coordinate input device according to claim 4, wherein the transmitting unit includes a modulator, and the receiving unit includes a demodulator. 6. The optical coordinate input device according to claim 4 or 5, wherein the receiving unit includes a receiving coil provided around the surface of the tablet.