JPH07200130A - Optical digitizer and its display device - Google Patents

Abstract

PURPOSE:To enable a normal blackboard or white board to be used as an input reference surface and to actually leave a writing by fitting a writing tool atop a stylus. CONSTITUTION:This digitizer has at least two light emitting means 34 and 35 which emit lights with a specific time difference, and also has the stylus 3 which is used on the input reference surface 1 of the blackboard, etc., and two linear image sensors 8a and 8b which are arranged in the periphery of the input reference surface 1 and photodetect the lights made incident from the light emitting means 34 and 35 through a slit. Further, the digitizer is equipped with an arithmetic means (CPU) 9 which detects the two-dimensional coordinates of the light emitting means 34 and 35 on the basis of the outputs from those linear image sensors and also finds coordinate data on the writing point of the stylus 3 on the input reference surface from the two-dimensional coordinates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical digitizer, and more particularly to an optical digitizer suitable for a handwriting input system and its display device.

[0002]

2. Description of the Related Art As an input system for handwriting, there are, for example, a pen input computer, an electronic blackboard, an electronic conference system and the like, and an input means called a digitizer is used for these.

In the electromagnetic induction system, a cursor or a pen having an electromagnetic induction coil is moved on a digitizer in which antenna wires are arranged in a matrix, and the electromagnetic induction coil is energized so that its position coordinate is determined. Is entered.

[0004]

However, since the one used in the electronic conference system and the like is used in parallel with the writing surface, it is inevitably large and expensive. Moreover, since the digitizer itself is not transparent, it cannot be used in combination with a rear projection display.

[0005]

The present invention has been made to solve the above-mentioned problems, and the structural feature in claim 1 is that at least the first and the second irradiating light that can be respectively identified. A stylus that has a light emitting means and is used for handwriting input on an input reference surface such as a blackboard, and a stylus that receives the light from the first and second light emitting means and that is used by the first and second light emitting means. It is provided with an optical coordinate detecting means for detecting a dimensional coordinate and a calculating means (CPU) for obtaining coordinate data of a designated position of the stylus on the input reference plane from the two-dimensional coordinate.

In this case, as the optical coordinate detecting means,
Besides a slit (or lens) and a linear image sensor, a method of illuminating the light emitting means in a time division manner for identification, a linear image having a light emitting means emitting light of different wavelengths and optical filters corresponding to the respective wavelengths There are a method of arranging the sensors in parallel and a method of recognizing, a method of recognizing by emitting light having different pulse widths from each light emitting means, and further, a distance measuring means using the propagation velocity of light may be used. That is, according to this distance measuring means, the distance between the light source and the light receiving position whose amplitude is modulated by the waveform of the reference oscillator is detected by the phase difference between the modulation signal and the light receiving signal.

According to a second aspect of the present invention, there is provided at least first and second light emitting means for irradiating light with a predetermined time difference, and a stylus used on an input reference surface such as a blackboard and arranged around the input reference surface. Two linear image sensors that receive the light from the first and second light emitting means that is incident through the slits, and the outputs of the linear image sensors based on the outputs from the linear image sensors. The present invention is characterized by including a computing means (CPU) for detecting two-dimensional coordinates and obtaining coordinate data of a designated position of the stylus on the input reference surface from the two-dimensional coordinates.

In this case, the stylus has a writing pressure detecting means for detecting that the stylus is in contact with the input reference surface, and the writing pressure detecting means controls blinking of the light emitting means. Is preferred.

The stylus may be provided with a writing instrument mounting means capable of mounting a writing instrument which leaves a handwriting on the input reference surface, and the choke may be held so as to be drawn out.

On the other hand, the optical digitizer is provided with a transmitting means for transmitting the coordinate data designated by the stylus, and a display means having a receiving means for the same coordinate data is prepared so that the instruction designated by the stylus can be provided. It is also possible to display the position on the display means via the transmitting means and the receiving means.

[0011]

According to the above construction, when the stylus comes into contact with the input reference surface, the first and second light emitting means blink with a predetermined time difference. The light is received by, for example, linear image sensors provided at two places on the left and right above the input reference plane.

The CPU detects the two-dimensional coordinates of the first and second light emitting means on the basis of the received light signal, and the coordinates of the pointing point (writing point) on the extension line of the first and second light emitting means from the coordinates. Calculate the data.

Further, by providing the transmitting means, it becomes possible to transmit the coordinate data of the writing point to, for example, the notebook personal computer and display the handwriting written on the input reference plane on the display.

[0014]

Embodiments of the present invention will be described below.
FIG. 1 shows the outline of the whole image. According to this, the optical digitizer comprises a stylus 3 used on the input reference plane 1. In this case, the input reference plane 1 may be a simple plate-like body such as a normal blackboard or a so-called whiteboard written with a marker pen.

Further, in this embodiment, the input reference plane 1
The linear image sensors 8a, 8
b is arranged.

Referring also to FIG. 2, the stylus 3 is provided with a cylindrical grip 31 having a slightly large diameter and a thin transparent pipe 32 attached to the rear end portion thereof. Although at least two light emitting means are arranged in the transparent pipe 32, four light emitting means are provided in this embodiment.

These light emitting means are composed of 180 ° omnidirectional light emitting diodes (LEDs), and two light emitting means are arranged face to face to form substantially two light emitting means. That is, the first LED 33a and the second LED 3
3b are arranged as a pair so as to face each other, so that any one of the lights is detected by the linear image sensors 8a and 8b regardless of the angle of the stylus 3.

With the same meaning, the third LED 33c
And the fourth LED 33d are arranged so as to face each other. For convenience of explanation, the first LED 33a and the second LED 33a
Including the LED 33b as the first light emitting means 34,
The third LED 33c and the fourth LED 33d are included in the second light emitting means 35.

A writing instrument mounting means 37 for mounting a writing instrument (for example, a marker pen) 36 is provided at the tip of the grip 3. In this embodiment, the writing instrument mounting means 3
Reference numeral 7 also serves as a writing pressure detector 37 ', an example of which is shown in FIG.

That is, the writing instrument mounting means 37 (writing pressure detector 37 ') has a bottomed cylindrical inner cylinder electrode 37a which holds the writing instrument 36 in a removable manner, and a bottomed cylindrical inner electrode 37a which is also disposed outside the electrode 37a. A cylindrical outer cylinder electrode 37b is provided, and a pressure sensitive resistor 37c made of, for example, carbon particles whose resistance value changes with pressure is filled between them.

The two electrodes 37a and 37b are movably connected to each other by an electrically insulating rubber 37d on the opening side thereof. Therefore, according to the writing pressure detector 37 ',
It is possible to detect a writing pressure vector applied to the writing instrument 36 in any direction.

In the above embodiment, a marker pen is used as the writing tool 36, but FIG. 4 shows an example in which a chalk is used. According to this, there is provided a cylindrical choke holder 41 which is held in the writing instrument mounting means 37 so as to be removable.

A female media is engraved in the choke holder 41, and the choke 42 is attached to a male screw member 43 screwed into the female media, and can be properly extended by turning it. Has been done.

Referring again to FIG. 2, a lighting control circuit 38 for light emitting means (LED) and a secondary battery 39 as a power source for the lighting control circuit 38 are provided in the grip 3, and the grip 3 has a tip portion. Is a charging terminal 3 for the secondary battery 39
9a is attached.

FIG. 5 shows a circuit example of the lighting control circuit 38 including the charging circuit for the secondary battery 39. According to this, the lighting control circuit 38 includes a comparator 52 for comparing the detection voltage obtained through the writing pressure detector 37 'with the reference voltage set by the variable resistor 51.

The comparator 52 turns on the switching transistor 54 when the voltage via the writing pressure detector 37 'becomes lower than the reference voltage due to the contact of the stylus 3 with the input reference surface 1, and the secondary battery is turned on. A lighting current is supplied from 39 to the multiplexer 53.

In this embodiment, the first light emitting means 34
(LEDs 33a, 33b) and second light emitting means 35
The lighting of the (LEDs 33c, 33d) is controlled at the timing shown in FIG. 6, and in FIG.
A flow chart for identifying 35 is shown.

Assuming that one cycle when the first and second light emitting means 34 and 35 blink is T, both the previous 2/3 cycle is turned on and the remaining 1/3 cycle is turned off. In this case, the phases of the first light emitting means 34 and the second light emitting means 35 are shifted by 1/3 cycle.

That is, assuming that the rising time (lighting time) of the first light emitting means 34 is t1, the second light emitting means 35 is already turned on at this time. The second light emitting means 35 is turned off at t2 when 1/3 cycle time has elapsed from t1 time, and only the first light emitting means 34 is turned on until 1/3 cycle time has elapsed from t2 time. And from t2 time 1 /
At t3 when three cycle times have elapsed, the first light emitting means 3
4 is turned off, and the second light emitting means 35 is turned on. This state continues until t4 after the elapse of the 1/3 cycle time, and this is repeated thereafter.

Looking at this in one cycle T of the first light emitting means 34, both the previous 1/3 cycle is lit, the middle ⅓ cycle is lit only by the first light emitting means 34, and the latter 1/3 cycle. In the three cycles, only the second light emitting means 35 is turned on.

Next, the relationship with the reading timing of the image sensor and the flow chart of the discrimination processing of the light emitting means of FIG. 7 will be described. In this embodiment, the reading cycle indicated by the circled numbers is T / 6, and this reading timing is asynchronous with the lighting control of the light emitting means 34, 35.

First, data is read from the linear image sensor 6 times (J = 1 to 6) continuously in one reading cycle T / 6 and stored in the memory A (I, J). In addition,
The number of pixels of the linear image sensor is 1 to N.

Next, in order to eliminate the influence of noise such as ambient light, the value (detected light amount) is set for all I and J.
Is smaller than a predetermined value TL, and the smaller one is set as 0 as a disturbance.

Thereafter, the sum of the detected light amounts obtained from 1 to N pixels is obtained for each of the sampling times, and the detected light quantity is the maximum among the sampling times. The value of J at that time is detected and M is determined.

That is, the detected light amount becomes maximum when both the first light emitting means 34 and the second light emitting means 35 are turned on, and therefore the number of times of sampling at that time is obtained. In the example of FIG. 6, the first time corresponds to that.

As a result, it is possible to distinguish whether the light incident on the linear image sensor is due to the first light emitting means 34 or the second light emitting means 35. That is, the data of the first light emitting means 34 is A (I, MOD (M
+1,6) +1) (where MOD is the operator of the remainder).

Describing according to the example of FIG. 6, since M = 1, MOD (1 + 1,6) has a remainder of 2. Therefore, 1 is added to this and the data of the first light emitting means 34 is A. (I,
3), and it is identified that the light at the time of the third sampling is from the first light emitting means 34.

The light emitted from the second light emitting means 35 is similarly identified as A (I, MOD (M + 3,6) +1). The above identification method can be applied to the case where the four LEDs 33a to 33d are turned on.

In this embodiment, the stylus 3 and C described later are used.
Since the PU and the PU are connected wirelessly, the blink control and the data sampling are asynchronous as described above. However, when the cable is connected, the blink control and the data sampling can be synchronized. Therefore, it becomes possible to more easily identify the light of each light emitting means.

A charger 70 for the stylus 3 is shown in FIG. The charger 70 has a cylindrical portion 71 that receives the grip tip side of the stylus 3, and a power supply terminal 72 that is paired with the charging terminal 39a is provided in the cylindrical portion 71.

A marker pen cap 73 is elastically held by a coil spring 74 between the power supply terminals 72. Reference numeral 75 is a charging power source, and reference numeral 76 is a mounting leg used when mounting on a blackboard or the like, as shown in FIG.

Therefore, according to the charger 70, the stylus 3 is inserted when not in use to automatically perform charging, and when the marker pen is used as a writing instrument, the cap is always used. You don't even have to cover it.

Next, the linear image sensors 8a and 8b will be described with reference to FIGS. 9A is a side view and FIG. 9B is a bottom view.
The linear image sensors 8a and 8b have the same configuration, and for example, a CCD (Charge Coupled De)
The light receiving portion 81 is formed by arranging the light receiving elements made of Vice) in a row, and one slit 82a.
It is composed of a slit plate 82 which is placed on 1.
A cylindrical lens may be used instead of the slit.

The light from each of the light emitting means 34 and 35 is received by the light receiving portion 81 of each of the linear image sensors 8a and 8b through the slit 82a. This received light signal is converted into digital data by A / D converters 9a and 9b, respectively, as shown in FIG.
Input to PU9.

Since the first light emitting means 34 and the second light emitting means 35 are turned on with a predetermined time difference, the CPU 9 determines the two-dimensional coordinates of the light emitting means 34, 35 based on the light receiving signals from both the linear image sensors 8a, 8b. Along with detecting
The coordinate data of the writing point on the extended line and in contact with the input reference plane 1 is calculated.

Here, a method of obtaining the coordinate value of the writing point of the stylus 3 will be described with reference to FIGS.

First, in FIG. 12, 2A is the XY coordinate plane defined on the input reference plane 1, and 2B is the XY coordinate plane.
A diagonal line of the coordinate plane 2A, O is the origin. XY coordinate plane 2
Assuming that A is a square whose one side length is L, the angles θ and ψ with respect to the position P (x, y) with respect to the diagonal line 2B are determined as shown in the figure.

As a result, as shown in FIG. 12, tan ψ, tan θ in the linear light receiving portions (linear image sensors) of the linear image sensors 8a, 8b.
Is determined. However, the distance from each corner to each linear image sensor is the unit length.

By using these values tan ψ and tan θ, the coordinate values x and y of the position P (x, y) can be obtained as follows.

In FIG. 12, tan (π / 4−θ) = x / y
And tan (π / 4−ψ) = (L−y) / x holds. In these equations, tan θ = p and tan ψ
Setting = q, the following equation holds.

X / y = (1−p) / (1 + p) = T ... (L−y) / x = (1−q) / (1 + q) = S ... Based on this equation, x, y When T is calculated from T, S, and L, the following is obtained.

X = TL / (ST + 1) y = L / (ST + 1) Thus, the two-dimensional coordinate values P1 (x1, y1) and P2 (x2, y) of the first light emitting means 34 and the second light emitting means 35 are obtained.
2) is required. Then, in order to obtain the designated position (writing point) on the extension line from each of the coordinate values, it is possible to do as shown in FIG.

That is, the coordinates of the designated position are P (x,
y) and the distances from the position to the first light emitting means 34 and the second light emitting means 35 are D1 and D2, respectively: x1-x: x2-x = D1: D2 y1-y: y2-y = D1: The relationship of D2 is established, and as a result, x = (D1 * x2-D2 * x1) / (D1-D2) y = (D1 * y2-D2 * y1) / (D1-D2) To P (x, y).

In this embodiment, the linear light receiving portion of the linear image sensor is parallel to the XY plane (perpendicular to the Z axis).
Since the slits are arranged so that the length direction of the slits is perpendicular to the XY plane (parallel to the Z axis), the (X, Y) of P
The coordinate value is not affected by the Z coordinate value, that is, the change in the angle of the light beam incident on the linear light receiving portion through the slit. The allowable range of this angle is determined by the positional relationship between the length of the slit and the linear light receiving portion because a light ray having an angle exceeding the slit length cannot be received.

Referring again to FIG. 1, in this embodiment, the display means 10 having the transmitter 9c for transmitting the coordinate data via the antenna 9d and correspondingly having the receiving means 10a is prepared. There is.

Therefore, according to this, it is possible to see the written contents of the instructor at the hand of each individual in a class or a lecture. The display unit 10 may be a display such as a laptop personal computer. It is also possible to record the written content on a floppy disk or the like, if necessary.

In place of the light emitting means of the above-mentioned embodiment, a light reflecting tape is attached and an appropriate light source is arranged around the input reference surface, and the stylus 3 is reflected by the light reflecting tape. You may make it detect the two-dimensional coordinate of. That is, in this specification, it should be understood that the light emitting means and the light reflecting tape are synonymous.

[0058]

As described above, according to the present invention, the light emitting means is provided at least at two positions other than the tip of the stylus, and the coordinates of the writing point of the stylus are obtained by the light emitting means. A normal blackboard or white board can be used for the surface, and a writing instrument can be attached to the tip of the stylus to actually leave handwriting. This means that an easy-to-use input system can be constructed at low cost.

Further, since the writing pressure detector is provided and the power of the light emitting means is turned on only when the stylus is in contact with the input reference surface, the power switch by manual operation becomes unnecessary and the power source is used as a power source. The secondary battery can be effectively used.

Furthermore, by transmitting the handwritten information written on the stylus by the transmitter, receiving the handwritten information at the receiver side, and displaying it on the personal display, for example, at a lecture. The contents of the blackboard can be viewed with certainty even in the back seats at the venue or the classroom.

This is good news especially for persons with weak eyesight, and it is necessary to store the content in a recording medium such as a floppy disk by using a notebook personal computer or the like to record it in a notebook or the like. The effect such as disappearing is also produced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an overall image of the present invention.

2 is a cross-sectional view of the stylus shown in FIG.

FIG. 3 is a sectional view of a writing pressure detector.

FIG. 4 is a cross-sectional view showing an example of a writing instrument mounting means applied to mounting a chalk.

FIG. 5 is a circuit diagram showing an LED lighting control circuit.

FIG. 6 is a timing chart showing an example of the lighting sequence of each LED.

FIG. 7 is a flowchart for identifying each light emitting means.

FIG. 8 is a cross-sectional view showing a stylus charger.

FIG. 9 is a schematic diagram for explaining a linear image sensor.

FIG. 10 is a schematic diagram showing how light is incident on a linear image sensor.

FIG. 11 is a block diagram showing a calculation means.

FIG. 12 is an explanatory diagram for explaining how to obtain a two-dimensional coordinate value of a light emitting unit.

FIG. 13 is an explanatory diagram for explaining how to obtain the coordinate value of a writing point from the two-dimensional coordinate value of two light emitting means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input reference plane 3 Stylus 9 Computing means (CPU) 9c Transmitter 10 Display means 34, 35 Light emitting means 36 Writing instrument 37 Writing instrument mounting means 37 'Writing pressure detector 38 Lighting control circuit 39 Secondary battery 42 Choke 52 Comparator 70 Charger 81 Light receiving part 82 Slit plate

Claims (6)

[Claims] 1. A stylus having at least first and second light emitting means for irradiating identifiable lights, the stylus being used for handwriting input on an input reference surface such as a blackboard, and the first and second stylus. Optical coordinate detection means for receiving the light from the second light emitting means and detecting the two-dimensional coordinates of the first and second light emitting means, and the pointing position of the stylus on the input reference plane from the two-dimensional coordinates. An optical digitizer, comprising: an arithmetic means (CPU) for obtaining coordinate data. 2. A stylus having at least first and second light emitting means for irradiating light with a predetermined time difference and used for handwriting input on an input reference plane such as a blackboard, and the periphery of the input reference plane. And two linear image sensors which are arranged in the light receiving means and receive light from the first and second light emitting means which are incident through the slits or lenses, and the first and the second linear image sensors based on outputs from these linear image sensors. (2) an optical system including a computing means (CPU) for detecting two-dimensional coordinates of the light emitting means and obtaining coordinate data of a designated position of the stylus on the input reference plane from the two-dimensional coordinates. Digitizer. 3. The stylus comprises writing pressure detection means for detecting that the stylus is in contact with the input reference surface,
3. The optical digitizer according to claim 1, wherein the writing pressure detecting means controls blinking of the light emitting means. 4. The optical digitizer according to claim 1, wherein the stylus is provided with a writing instrument mounting means capable of mounting a writing instrument which leaves a handwriting on the input reference surface. 5. The optical digitizer according to claim 4, wherein the writing instrument is a chalk, and the writing instrument mounting means holds the chalk so that the chalk can be drawn out. 6. A stylus used for performing handwriting input on an input reference plane such as a blackboard, the stylus having at least first and second light emitting means for irradiating light that is distinguishable from each other. Optical coordinate detection means for receiving the light from the second light emitting means and detecting the two-dimensional coordinates of the first and second light emitting means, and the pointing position of the stylus on the input reference plane from the two-dimensional coordinates. An arithmetic means (CPU) for obtaining coordinate data, a transmitting means for transmitting the same coordinate data, and a display means having a receiving means for the same coordinate data are provided, and the indicated position indicated by the stylus is transmitted to the transmitting means and the above. A display device using an optical digitizer, which is capable of displaying on the display means via a receiving means.