JP2000347805A - Coordinate input device and its control method, and computer-readable memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the coordinate input device which suppresses the influence of disturbing light to enable high-resolution and high-performance coordinate input. SOLUTION: A light spot is detected by linear sensors 20X and 20Y. A sensor control part 31 calculates the difference between a 1st signal and a 2nd signal that the linear sensors 20X and 20Y output by detecting the ON state and OFF state of the light spot. Then a control signal based upon the peak level of the difference signal is generated. The device is equipped with a display control means which controls display properties of an image displayed according to the light spot on the basis of the control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for generating a light spot by irradiating a predetermined position on a coordinate input screen with light from a pointing device and generating coordinates corresponding to the light spot, and a control method therefor. , A computer readable memory.

[0002]

2. Description of the Related Art A CCD area sensor is used as a coordinate input device used to control a computer connected externally or to write characters, figures, etc. by directly inputting coordinates on a large display screen with a pointing tool. An image of a light spot on the screen using an image sensor or a linear sensor, image processing such as using barycentric coordinates or pattern matching is performed, and a coordinate value is calculated and output. Devices using an analog device that can obtain an output voltage corresponding to a position) are known.

[0003] For example, Japanese Patent Publication No. 7-76902 discloses an apparatus for detecting a coordinate by imaging a light spot formed by a parallel beam of visible light with a video camera and simultaneously transmitting and receiving a control signal using infrared diffused light. ing. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent Publication No. 274266 discloses an apparatus for detecting coordinates using a linear CCD sensor and a special optical mask. On the other hand, Japanese Patent No. 2503182 discloses a configuration of a device using a PSD and a method of correcting output coordinates.

[0004] In recent years, the brightness of the screen of a large screen display has been improved, and it has become possible to sufficiently use it even in a brightly lit environment, and the demand has been expanding. And it is becoming increasingly necessary that the coordinate input device be insensitive to disturbance light so that it can be used in an environment combined with such a large screen display. In recent years, devices using infrared rays as wireless communication means have been increasing, and disturbance light has been increasing for both infrared rays and visible light. One of the characteristics.

[0005]

However, in a coordinate input device using a CCD sensor as disclosed in Japanese Patent Publication No. 7-76902 and Japanese Patent Laid-Open No. 6-274266, disturbance light is suppressed only by an optical filter. Can not do.

On the other hand, in a coordinate input device using a PSD as disclosed in Japanese Patent No. 2503182, the influence of disturbance light can be suppressed by frequency-modulating the light intensity and synchronously detecting the modulated wave. Therefore, when used in combination with an optical filter, it has strong characteristics against disturbance light.

[0007] In addition, the resolution of the large-screen display has been improved as well as the brightness. For this reason, it is necessary to improve the resolution of the coordinate input device, but there is a problem in this point in the coordinate input device using the PSD which is strong against disturbance light. That is, the dynamic range of the sensor output voltage directly corresponds to the input range. Therefore, for example, when the whole is decomposed into 1000 coordinates, an S / N ratio of at least 60 dB or more is required, and digital correction of a linearity error is indispensable as disclosed in Japanese Patent No. 2503182. Therefore, a high-precision analog circuit, a multi-bit AD converter, and an arithmetic circuit are required. Furthermore, since the S / N ratio of the sensor output signal depends on the amount of light and the sharpness of the light spot, suppression of disturbance light alone is not sufficient, and a bright and highly accurate optical system is also required. For this reason, the device itself is very expensive and large.

Further, as a technique for increasing the resolution by using a CCD sensor, Japanese Patent Publication No. 7-76902 discloses that a plurality of video cameras are used at the same time. Become. In the case of a single video camera having a large number of pixels, the size and cost of the video camera are further increased than when a plurality of cameras are used. Further, in order to achieve a resolution higher than the number of pixels by image processing, high-speed processing of enormous image data is required, and it is very large and expensive for real-time operation.

In Japanese Patent Application Laid-Open No. Hei 6-274266, a high optical resolution is obtained by a special optical mask and signal processing.
If the ratio can be secured, high resolution can be achieved. However, in actuality, the linear sensor forms an image in a linear shape, and cannot separate from in-plane disturbance light compared to an area sensor that becomes a point image. Therefore, the linear sensor is easily affected by disturbance light and has little disturbance light. There is a problem that it becomes practical only in a special environment.

In a coordinate input device for detecting the position of a light spot, it is important to obtain a stable and sufficient light amount of a light spot for high-precision coordinate detection. In particular, there is a problem that the amount of light is insufficient when the pointing device is tilted in a peripheral portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a coordinate input device and a control method thereof that suppress the influence of disturbance light and enable high-resolution and high-performance coordinate input.
It is an object to provide a computer readable memory.

[0012]

A coordinate input device according to the present invention for achieving the above object has the following arrangement.
That is, a coordinate input device that irradiates light from a pointing tool to a predetermined position on a coordinate input screen to generate a light spot and generates coordinates corresponding to the light spot, and a detecting unit that detects the light spot. A detecting means for detecting a lighting state and a non-lighting state of the light spot, calculating a difference signal between a first signal and a second signal, and generating a control signal based on a peak level of the difference signal. Generating means.

Preferably, the apparatus further comprises display control means for controlling a display attribute of an image displayed based on the light spot based on the control signal.

[0014] Preferably, the display attribute includes at least one of a color and a size of a displayed cursor, or a color, shading and a size of a coordinate image generated corresponding to the light spot. .

[0015] Preferably, a display control means for controlling a display attribute of an image displayed based on the light spot based on the control signal and a coordinate output signal generated corresponding to the light spot. Further provision.

Preferably, when a light-transmitting member for covering the light-emitting element of the pointing device is provided, the display control means sets the state of attachment of the light-transmitting member to the pointing device based on the control signal. And a notifying unit for notifying the state of attachment of the translucent member to the pointing device based on the detection result of the detecting unit.

Preferably, when a light-transmitting member for covering the light-emitting element of the pointing device is provided, the display control means is configured to perform a control based on the control signal and a coordinate output signal generated corresponding to the light spot. Detecting means for detecting the state of attachment of the translucent member to the pointing device, and notifying means for notifying the state of attachment of the translucent member to the pointing device based on the detection result of the detecting unit. Prepare.

A control method of a coordinate input device according to the present invention for achieving the above object has the following configuration. That is,
A control method for a coordinate input device for generating a light spot by irradiating light from a pointing tool to a predetermined position on a coordinate input screen and generating coordinates corresponding to the light spot, wherein a detecting step of detecting the light spot A detecting step of detecting a lighting state and a non-lighting state of the light spot, and calculating a difference signal between a first signal and a second signal, and a control signal based on a peak level of the difference signal. Generating step.

A computer readable memory according to the present invention for achieving the above object has the following configuration. That is,
A computer-readable memory that stores a program code for controlling a coordinate input device that generates a light spot by irradiating a predetermined position on a coordinate input screen with light from a pointing tool, and generates coordinates corresponding to the light spot. A program code of a detecting step of detecting the light spot, and a difference step of calculating a difference signal between a first signal and a second signal which are output by detecting the lighting state and the non-lighting state of the light spot. A program code for generating a control signal based on a peak level of the difference signal.

[0020]

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

First, a schematic configuration of an optical coordinate input device according to the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing a schematic configuration of a coordinate input device according to the present embodiment.

The coordinate input device is roughly divided into an indicator 4 for forming a light spot 5 on a screen 10 as a coordinate input surface, and a coordinate detector 1 for detecting the position coordinates of the light spot 5 on the screen 10 and the like. Consists of FIG. 1 shows a screen 10 as an output device together with those configurations.
2 shows a projection display 8 for displaying an image, position coordinates, and the like.

The coordinate detector 1 includes a coordinate detection sensor unit 2 and
The controller 3 includes a controller 3 for controlling the coordinate detection sensor unit 2 and calculating coordinates, a light receiving element 6, and a signal processing unit 7. The controller 3 detects the coordinate position of the light spot 5 on the screen 10 and a control signal corresponding to the state of each switch of the pointing tool 4 described later, and communicates the information to an external connection device (not shown) by the controller 3. ing.

The projection display device 8 includes an image signal processing unit 81 to which an image signal from a display signal source, which is an external connection device such as a host computer (not shown), is input, a liquid crystal panel 82 controlled by the image signal processing unit 81, Lamp 83, mirror 8
4. An illumination optical system including a condenser lens 85, and a projection lens 86 for projecting an image of the liquid crystal panel 82 onto the screen 10,
Can be displayed. Since the screen 10 has an appropriate light diffusing property in order to widen the observation range of the projected image, the light beam emitted from the pointing tool 4 is also diffused at the position of the light spot 5, and the position on the screen and A part of the light diffused at the position of the light spot 5 enters the coordinate detector 1 irrespective of the direction of the light beam.

With such a configuration, by inputting character information and line drawing information on the screen 10 by the pointing tool 4 and displaying the information on the projection display device 8, it is as if "paper and pencil". In addition to enabling input / output of information in a relationship, it is configured such that input operations such as button operation and icon selection can be freely performed. <Detailed Description of Pointing Tool 4> FIG. 2 is a diagram showing a detailed configuration of the pointing tool of the present embodiment.

The pointing device 4 is a light emitting element 4 such as a semiconductor laser for emitting a light beam or an LED for emitting infrared light.
1, a light emission control unit 42 for driving and controlling the light emission, a power supply unit 44, operation switches 43A to 43D, a power supply unit 44 such as a battery, and a cap 46 made of a detachable translucent member that covers the light emitting element 41. And built-in. The light emission control unit 42 changes the state of the operation switches 43A to 43D.
Light emission control in which a control signal is superimposed is performed by ON (ON) / OFF (OFF) of light emission and a modulation method described later.

FIG. 3 is a diagram showing an operation mode of the pointing device of the present embodiment.

The switches A to D correspond to the switch 43A of FIG.
~ 43D. In FIG. 3, “light emission” corresponds to a light emission signal (coordinate signal), and “pen down” and “pen button” correspond to control signals.

The operator holds the pointing device 4 and holds the screen 1
Point its tip at zero. At this time, the switch 43A is arranged at a position where the thumb naturally touches, and when pressed, the light beam 45 is emitted. As a result, the light spot 5 is generated on the screen 10, and the coordinate signal starts to be output by a predetermined process. However, in this state, the pen down and pen button control signals are OFF. For this reason, on the screen 10, only the indication of the position indicated to the operator by the movement of the cursor or the switching of the highlight of the button is performed.

By pressing the switches 43C and 43D arranged at positions where the index finger and the middle finger naturally touch, the control signal of the pen down and the pen button becomes a signal superimposed on the light emission signal as shown in FIG. . That is, by pressing the switch 43C, a pen-down state is established, and screen control such as starting input of characters and line drawings and selecting and determining a button can be executed. Switch 43
By pressing D, the state of the pen button is established, and it is possible to correspond to another function such as calling a menu. This allows the operator to quickly and accurately draw characters and figures at any position on the screen 10 with one hand,
By selecting buttons and menus, it can be operated lightly.

A switch 4 is provided at the tip of the pointing device 4.
A switch 3B is provided and operates when the pointing tool 4 is pressed against the screen 10. The operator grips the pointing device 4 and touches the tip of the pointing device on the screen 10.
, A pen-down state is established, so that a natural pen input operation can be performed without performing extra button operations.

The switch 43A has a role of a pen button. Of course switch 43A without pressing on the screen
You can also move the cursor only by pressing. Actually, the operability and accuracy are much better when the characters and graphics are input directly from the screen than when the characters or figures are input from the screen. In the present embodiment, even if the user is away from the screen by using the four switches, or immediately before, a natural and comfortable operation can be performed, and the user can use the switch depending on the case. I have. Furthermore, if it is only for direct input (not used as a pointer), a diffused light source may be used instead of a light beam.
Can also be used.

Further, when two kinds of pointing tools 4 for proximity and remote use are used as described above, two or more people operate simultaneously, or a plurality of pointing tools 4 having different attributes such as color and thickness are used. For this reason, the light emission control unit 42 is set to transmit a unique ID number together with a control signal. In accordance with the transmitted ID number, attributes such as the thickness and color of the drawn line are determined by software on the external connection device side, and the setting can be changed by a button or menu on the screen 10. Can be. For this operation, an operation button or the like may be separately provided on the indicating tool 4 to transmit a change instruction signal. For these settings, the state is maintained in the indicating tool 4 or the coordinate detector 1. It is also possible to configure so that attribute information, instead of the ID number, is transmitted to the externally connected device.

Further, such additional operation buttons can be set so that other functions such as blinking of a display device, switching of a signal source, operation of a recording device, and the like can be performed.
Further, by providing pressure detection means in one or both of the switches 43A and 43B, pen pressure detection is performed, and various useful signals such as transmission of this pen pressure data together with a control signal can be transmitted. is there.

When the switch 43A or the switch 43B of the indicator 4 is turned on, light emission starts, and the light emission signal is a header consisting of a reader unit composed of a relatively long continuous pulse train and a code (such as a maker ID) following the reader unit. The information is sequentially output according to a predetermined order and format of a transmission data string including a pen ID and a control signal (see FIG. 5, LSG signal).

In the embodiment of the present invention, in each data bit, the "1" bit is formed in a modulation format having an interval twice as long as the "0" bit. Various types can be used. However, as will be described later, it is desirable that the average amount of light is constant for coordinate detection, and that the clock component is sufficiently large for tuning the PLL. Considering that there is no problem even if the degree is relatively high, in the present embodiment, 6 bits (64 bits) are used.
) Of the 10-bit-length code, the number of 1s and 0s is the same, and the number of consecutive 1s or 0s is 3 or less.
It is encoded by the method of assigning to each code. By employing such an encoding method, the average power becomes constant and a sufficient clock component is included, so that a stable synchronization signal can be easily generated at the time of demodulation.

As described above, the pen down and pen button control signals are 2 bits, but other long data such as ID must be transmitted. Therefore,
In this embodiment, the first two bits are a control signal, the next two bits are a content identification code (for example, the pen pressure signal is 00, the ID is 11, etc.), and the next two bits are these bits. Parity, and subsequently, 16-bit data and 2-bit parity are arranged to form one block of data. When such data is encoded by the method described above, a signal having a length of 40 bits is obtained.
A 10-bit sync code is added to the head of the code. This sync code is distinguished from a data word by using a special code of 4 0s, 5 consecutive 1s, or an inverted pattern thereof (switching depending on whether the end of the previous block is 1 or 0). It is easy to identify the position even in the middle of the data string and restore the data. Therefore, one block becomes a transmission signal having a length of 50 bits, which means that the control signal and data such as a 16-bit ID or writing pressure are transmitted.

In this embodiment, the first frequency is 60 kHz.
The second frequency is 7.5 kHz, which is 1/8 of the above.
Since the above-described coding method is employed, the average transmission bit rate is 2/3 of 5 kHz. Furthermore, since one block is 50 bits, 100 Hz is 1 bit.
This means that 24-bit data is transmitted in the block. Therefore, the effective bit rate excluding parity is 2
000 bits / sec. Although the redundancy is high,
This method can prevent erroneous detection and facilitate synchronization with a very simple configuration. In addition, by using a phase synchronization signal for sensor control described later and a check for a repetition period of a sync code, even if a short dropout occurs in the signal, the signal can be followed. The discrimination from the case where a quick operation such as double tap is performed can be surely performed by the presence or absence of the header signal. <Detailed Description of Coordinate Detector 1> FIG. 4 is a diagram showing a detailed configuration of the coordinate detector of the present embodiment.

The coordinate detector 1 includes a light receiving element 6 for detecting the amount of light with high sensitivity by a condensing optical system, and four linear sensors 20 for detecting an incoming direction of light by an imaging optical system.
X and 20Y are provided. Then, the light beam from the light emitting element 41 incorporated in the pointing device 4 receives the diffused light from the light spot 5 generated on the screen 10. <Explanation of Operation of Light-Condensing Optical System> The light-receiving element 6 is provided with a light-collecting lens 6a as a light-condensing optical system, and detects a light amount of a predetermined wavelength with high sensitivity from the entire range on the screen 10. This detection output is detected by the frequency detection unit 71, and then demodulated by the control signal detection unit 72 into a digital signal including data such as a control signal (a signal superimposed by the light emission control unit 42 of the indicator 4).

A timing chart in the control signal restoring operation will be described with reference to FIG.

FIG. 5 is a timing chart in the control signal restoring operation of the present embodiment.

The data signal composed of the bit string as described above is detected by the light receiving element 6 as a light output signal LSG.
The frequency is detected by the frequency detector 71. The frequency detection unit 71
The optical output signal LSG is configured to be tuned to the pulse period of the highest first frequency in the optical output signal LSG. When used in combination with an optical filter, it is not affected by disturbance light.
The modulation signal CMD is demodulated. This detection method is similar to a widely used infrared remote controller, and is a highly reliable wireless communication method.

In this embodiment, the first frequency is set to 60 KHz, which is higher than that of a generally used infrared remote controller, so that no malfunction occurs even when used at the same time. The first frequency can be set to the same band as a generally used infrared remote controller. In such a case, malfunction is prevented by identifying the first frequency with an ID or the like.

The modulated signal CMD detected by the frequency detector 71 is interpreted as digital data by the control signal detector 72, and the above-described control signals such as pen-down and pen buttons are restored. The restored control signal is sent to the communication control unit 33. The modulation signal C
The code modulation cycle, which is the second frequency included in the MD, is detected by the sensor control unit 31, and this signal controls the linear sensors 20X and 20Y. That is, the sensor control unit 31 resets at the timing of the header shown in FIG.
A signal LCK synchronized with the falling edge of MD is generated.

Therefore, the generated signal LCK is a signal of a constant frequency synchronized with the presence or absence of light emission of the indicator 4. Further, from the modulation signal CMD, a signal LON indicating presence / absence of light input and a sensor reset signal RCL activated by the signal LON are generated. While the sensor reset signal RCL is at the high level, the two linear sensors 20X and 20Y are reset, and a synchronous integration operation described later is started at the falling timing of the sensor reset signal RCL synchronized with the rising of the signal LCK.

On the other hand, when the control signal detecting section 72 detects the header section and confirms that the input from the pointing device 4 has been started instead of other equipment or noise, a signal indicating this confirmation is transmitted to the communication control section 33. Is transmitted to the sensor control unit 31, the signal CON indicating the validity of the operation of the linear sensors 20X and 20Y is set to a high level, and the operation of the coordinate calculation unit 32 is started.

FIG. 6 shows a timing chart at the end of the series of operations when the light output signal LSG is lost. When the modulation signal CMD detected from the optical output signal LSG keeps the low level for a certain period of time or more, the signal LON indicating the presence or absence of the optical input goes low, and the signal CON indicating the validity of the sensor operation also goes low. As a result, the output operation of the coordinates by the linear sensors 20X and 20Y ends. <Explanation of Operation of Imaging Optical System> FIG. 7 is a diagram showing an arrangement relationship between the linear sensors 20X and 20Y of the present embodiment.

In FIG. 7, the image of the light spot 5 is linearly formed on the photosensitive portions 21X and 21Y of the linear sensors 20X and 20Y by the cylindrical lenses 90X and 90Y as the image forming optical system. By arranging these linear sensors 20X and 20Y accurately at right angles, the X coordinate and Y
An output having a peak at a pixel reflecting the coordinates is obtained.

The two linear sensors 20
X and 20Y are controlled by a sensor control unit 31, and output signals are output from an AD conversion unit 31 connected to the sensor control unit 31.
A sends it to the coordinate calculation unit 32 as a digital signal. The coordinate calculation unit 32 calculates an output coordinate value from the input digital signal, and outputs the calculation result to the control signal detection unit 72.
The data is transmitted to an external control device (not shown) by a predetermined communication method through the communication control unit 33 together with data such as a control signal from the control unit. When performing an unusual operation (for example, setting a user calibration value) such as at the time of adjustment, the communication control unit 33
Sends a mode switching signal to the sensor control unit 31 and the coordinate calculation unit 32.

In the present invention, the focus is adjusted so that the image of the light spot 5 has an image width several times as large as the pixels of the linear sensors 20X and 20Y, and blur is intentionally caused. 1.5mm diameter plastic cylindrical lens, pixel pitch about 15μm, effective 64 pixels linear CCD, infrared LE
According to the experiment using D, when the sharpest image is formed, the image width becomes 15 μm or less over the entire angle of view of about 40 degrees. In such a state, it has been found that the result of the inter-pixel division calculation is distorted stepwise. Therefore, if the image width is 3
When the position of the lens was adjusted to be about 0 to 60 μm, very smooth coordinate data was obtained. Of course, if the image is largely blurred, the peak level will be reduced. Therefore, an image width of about several pixels is optimal. Using a CCD with a small number of pixels and a moderately blurred optical system
It is one of the points of the present invention. By using such a combination, a coordinate input device with a small amount of calculation data, a very high resolution, a high accuracy, a high speed and a low cost can be realized with a small sensor and an optical system. it can.

The X-coordinate detecting linear sensor 20X and the Y-coordinate detecting linear sensor 20Y arranged in an array have the same configuration. The detailed configuration will be described with reference to FIG.

FIG. 8 is a diagram showing a detailed configuration of the linear sensor of this embodiment.

The sensor array 21 serving as a light receiving section is composed of N pixels (64 pixels in this embodiment), and charges corresponding to the amount of received light are stored in the integrating section 22. The integrator 22 calculates N
It can be reset by applying a voltage to the gate ICG, so that an electronic shutter operation is possible.
The electric charge stored in the integration unit 22 is transferred to the storage unit 23 by applying a pulse voltage to the electrode ST. The storage section 23 is composed of 2N pieces, and charges are separately stored corresponding to H (high level) and L (low level) of the IRCLK signal synchronized with the light emission timing of the indicator 4. Thereafter, the charges separately accumulated in synchronization with the blinking of the light are transferred to the 2N linear CCD units 25 via the 2N shift units 24 provided for simplifying the transfer clock. Is done.

Thus, the linear CCD section 25 has N
The electric charges corresponding to the blinking of the light output from the sensor output of the pixel are stored adjacent to each other. These linear CCDs
The charges arranged in the part 25 are 2N ring CCs.
The data is sequentially transferred to the D unit 26. This ring CCD 26
After being emptied by the CLR unit 27 by the CLR signal, the charges from the linear CCD unit 25 are sequentially accumulated.

The charges thus accumulated are read out by the amplifier 29. The amplifier 29 is non-destructive and outputs a voltage proportional to the amount of accumulated charge. Actually, the difference between the adjacent charge amounts, that is, the light emitting element 4
A value obtained by subtracting the charge amount at the time of non-lighting from the charge amount at the time of lighting 1 is amplified and output.

At this time, the linear sensors 20X, 2
An example of the output waveform of 0Y will be described with reference to FIG.

FIG. 9 is a diagram showing an example of the output waveform of the linear sensor according to the present embodiment.

In FIG. 9, the waveform B is a waveform when only the signal when the light emitting element 41 is turned on is read out, and the waveform A is a waveform when the light emitting element 41 is not turned on, that is, only the disturbance light (see FIG. 9). As shown in FIG. 8, the charges of the pixels corresponding to the waveforms A and B are arranged adjacent to each other on the ring CCD 26). The amplifier 29 calculates the difference value (B
-A waveform) is output non-destructively.
As a result, a signal of only an image from the pointing tool 4 can be obtained, and stable coordinate input can be performed without being affected by disturbance light (noise).

If the maximum value of the waveform B-A shown in FIG. 9 is defined as the PEAK value, the linear sensor 2
If the accumulation time during which the linear sensors 0X and 20Y function is increased, the PEAK value is increased in accordance with the time.
In other words, if the time corresponding to one cycle of the IRCLK signal is defined as a unit accumulation time and the number of accumulations n is defined using the unit as the unit, the PEAK value increases by increasing the number of accumulations n. Then, by detecting that the PEAK value has reached the predetermined magnitude TH1, it is possible to always obtain an output waveform of a constant quality.

On the other hand, when the disturbance light is very strong, the ring CC may be used before the peak of the differential waveform BA becomes sufficiently large.
The transfer charge of D26 may be saturated. In consideration of such a case, each linear sensor of the linear sensors 20X and 20Y is provided with an SKIM unit 28 having a skim function. The SKIM unit 28 monitors the level of the non-lighting signal. In FIG. 10, when the signal level exceeds a predetermined value at the n-th An (in FIG. 10, a dashed line in the figure), a certain amount of charge is A and B. From each pixel.
As a result, in the next (n + 1) -th time, a waveform as shown in An + 1 is obtained, and by repeating this, even if there is extremely strong disturbance light, signal charges can be accumulated without being saturated.

Therefore, even if the amount of blinking light from the pointing device 4 is weak, by continuing the integration operation many times, a sufficiently large signal waveform can be obtained.
In particular, when a light source in the visible light range is used for the indicator 4, the display image signal is superimposed. Therefore, by using the above-described skim function and difference output, it is possible to obtain a sharp waveform with very little noise. Becomes

Next, operation control of the linear sensors 20X and 20Y will be described with reference to FIG.

FIG. 11 is a flowchart showing the operation control of the linear sensor of this embodiment. When the sensor control section 31 starts the sensor control operation, the signal CON is monitored in step S102. If the signal CON is at the high level (YES in step S102), the process proceeds to step S103, and the number of accumulations n is reset to zero.
Then, in step S104, the PE of the sensor output is output.
It is determined whether the AK value (peak level) is greater than a predetermined value TH1.

If the PEAK value is less than the predetermined value TH1 (NO in step S104), it is determined in step S105 whether the number of accumulations n is greater than a first predetermined number n0. If the number of accumulations n is less than the first predetermined number of times n0 (NO in step S105), the process proceeds to step S106, where the number of accumulations n is incremented by one, and step S1 is performed.
Return to 04. On the other hand, if the PEAK value is larger than the predetermined value TH1 (YES in step S104), that is, if the light amount is sufficiently accumulated and a signal level sufficient for performing accurate coordinate value calculation is obtained, the process proceeds to step S114, and the level control signal Is set to Hi. If the accumulation number n is larger than the first predetermined number n0 (step S5).
If YES in step 105), that is, if the light amount is not sufficiently accumulated, the process proceeds to step S115, and the flag PDATA, which is the level control signal, is set to Low.

Then, in step S107, the integration stop signal RON becomes high level (H), and the integration operation is stopped. Then, the coordinate value calculation process by the coordinate calculation unit 32 is started.

On the other hand, a flag PDA which is a level control signal
The TA is transmitted to an external control device (not shown) by a predetermined communication method via the communication control unit 33 together with data such as output coordinate values and control signals. When the level control signal flag PDATA is Low, the external control device performs control to notify the operator that a sufficient light amount of the light spot 5 on the screen 10 cannot be obtained. Specifically, the display attributes on the screen display, for example, changing the color and size of the displayed cursor or the color, shading, and size of the drawn dot to a state different from the normal state, and calling the operator's attention I do.

Here, the changing process when changing the color of the cursor will be described with reference to FIG.

FIG. 12 is a flowchart showing the change processing when changing the color of the cursor according to the present embodiment.

First, in step S302, it is determined whether or not the flag PDATA is Low. If not Low (NO in step S302), step S30
Go to step 4 and change the color of the cursor to black. On the other hand, if it is Low (YES in step S302), step S30
Go to 3 and change the cursor color to red.

By this change processing, the operator can know that the amount of light is insufficient by changing the color of the normally black cursor to red. In the present embodiment, in particular, when detecting a reduction in the amount of light emission due to a decrease in the current voltage due to the consumption of the power supply unit 44 incorporated in the pointing device 4, the predetermined value TH1 is a light amount limit value at which required coordinate detection accuracy is obtained. Set to. Also,
When the value is below the predetermined value TH1, the operator is notified of the shortage of the light amount by the color of the cursor or the like, and urges the replacement and charging of the power supply unit 44. Of course, a display prompting "battery replacement" or "charging" may be directly displayed.

In the flowchart of FIG.
In order to detect the K value more finely, a predetermined value TH2 different from the predetermined value TH1 as shown in FIG.
A level control signal called Mid may be generated between Hi and Low of DATA (2 bits in this case). In this case, in the flow chart of FIG. 12, as shown in the flow chart of FIG. 14, the change in the color of the cursor can be indicated by blue in the middle between black and red, and more detailed information on the light amount can be reported. Furthermore, the situation where a sufficient light amount of the light spot 5 cannot be obtained is that the pointing tool 4 is extremely far from the screen 10, the pointing tool 4 is laid too much on the screen 10, the pointing area is the input area. Since the situation is such that the situation is too close to the periphery, a message or the like prompting the situation may be displayed to the operator. In addition, a display control unit (not shown) that controls the display attribute on the screen 10 according to the light amount of the light spot 5 in response to the level control signal may be provided in the communication control unit 33 to perform the display control. .

Returning to the description of FIG. 11, in step S108, it is determined whether or not the number of accumulations n is greater than a second predetermined number of times n1. If the accumulation number n is less than the first predetermined number n1 (NO in step S108), step S109
Then, the number of accumulations n is incremented by 1, and the process returns to step S108. On the other hand, the accumulation number n is equal to the first predetermined number n1.
If it is larger (YES in step S105), the process proceeds to step S110, where the integration stop signal RON goes low, and at the same time, several times the period of the signal LCK (2 in FIG. 10).
During this time, the sensor reset signal RCL goes high. Next, in step S112, the signal CON is monitored. If the signal CON is at the high level (YES in step S112), the process proceeds to step S103. on the other hand,
When the signal CON is at a low level (step S112)
NO), the process proceeds to step S111, and waits for one processing cycle.

That is, while the signal CON is at the high level, this operation is repeated, and the coordinate value calculation is performed at intervals determined by the predetermined number n1. Also, under the influence of garbage,
Step S111 is provided so that the state is maintained only once even if the signal CON drops. if,
If the signal CON is at the low level for two consecutive periods (NO in step S102), the process proceeds to step S113, where the flag pon is reset to 0, a state waiting for a sync signal is returned, and the state returns to the initial state.

The dropout countermeasure portion can be longer than one cycle, and it goes without saying that the portion may be shortened if the disturbance is small. Note that the same operation can be performed by setting one cycle here as a natural number multiple of the above-described data block cycle and matching the sync code timing, and using a sync code detection signal instead of the signal CON.

The light of the indicator 4 reaching the coordinate detector varies due to the consumption of the power supply (battery) 44 incorporated in the indicator 4 and also varies depending on the attitude of the indicator 4. In particular, when the light diffusing property of the screen 10 is small, the front luminance of the displayed image is improved, but the fluctuation of the amount of light input to the sensor due to the posture of the pointing tool 4 is increased. However, in the present invention, even in such a case, since the number of integrations automatically follows and an output signal that is always stable can be obtained, an excellent effect of enabling stable coordinate detection can be obtained. . Furthermore, if the level of the output signal is insufficient, the operator is notified of the insufficient level, and is alerted to prompt a correct instruction method, so that a stable output signal can be always obtained.

When light is incident on the sensor without being scattered much as a pointer, considerably intense light enters, but it is clear that stable coordinates can be detected even in such a case.

Further, the LE used by directly touching the screen is used.
When a pen using D and a pointer are used together, LEDs having a larger light amount can be used.
The first predetermined number n0 and the second predetermined number n1, which are the number of integrations shown in 1, are switched by determining whether the pen or the pointer by the ID signal, and the sampling is performed at a high speed in the case of the pen and at a low speed in the case of the pointer. It is also possible. Actually, it is impossible to draw a delicate drawing operation like a character input with a pointer. Rather, it is more convenient to draw a smooth line by low-speed sampling, and it is effective to provide such switching.

As described above, the high-frequency carrier is added to the blinking light, and the timing of the integration operation is controlled by the demodulated signal of a predetermined period obtained by frequency-detecting the carrier. The image unit and the image unit can be synchronized cordlessly, and an easy-to-use coordinate input device can be realized. Further, by using a laser beam, there is obtained an excellent advantage that it is possible to easily work at a position away from the screen. Further, since the integration control means for detecting that the peak level in the difference signal from the integration section exceeds a predetermined level and stopping the integration operation is provided, the signal of the light spot image having a substantially constant level even when the light amount changes. Can be created, whereby a stable and high-resolution coordinate calculation result can always be obtained.

In the above embodiment in which the peak level is detected and the level control signal is generated, the operator is informed mainly when the light quantity is insufficient and the peak level does not exceed the predetermined level. However, as shown in FIG. 15, a plurality of levels when the predetermined level is exceeded may be detected simultaneously with the detection of the shortage of the light quantity. In FIG. 15, for this purpose, it is determined whether or not the number of integrations is larger than a predetermined value n2 with respect to a predetermined value TH1.
If it is not large, PDATA = Hi is generated because the light amount is the highest. Further, for fine detection, an AD converter for the peak level value may be provided and the value may be used.

Further, by processing the level control signal together with the designated area information based on the result of the coordinate calculation processing described below, the detected light quantity is not affected by the tendency that the detected light quantity decreases from the center to the peripheral area. , For example, pointing device 4
Corresponding to only the inclination of.
For example, FIG. 16 shows an example of a simple process. FIG. 15 and FIG.
The combination of 6 not only notifies the user of the lack of light amount, but also expands the operational possibilities by using, for example, an application in which the color, shading, and size of the cursor or drawing dot changes depending on the input inclination of the pointing tool 4. Can be. When detecting a decrease in the amount of light emission due to a decrease in the current voltage due to the consumption of the power supply unit 44 incorporated in the pointing device 4,
It is possible to more accurately prompt the operator to replace or charge the battery or the like without being affected by the input area.

Another embodiment will be described with respect to the control by peak level detection of the present invention. As shown in FIG.
In order to prevent the light emitting element 41 from being worn or scratched due to friction with the screen, when the indicator 4 is configured to cover the light emitting element 41 with a cap 46 made of a translucent member, the cap 46 may be damaged. If the coordinate detection becomes inconvenient, the cap 46 may be removed for replacement. The light-emitting element 4 with the cap 46 removed and not mounted
When 1 emits light, there is a possibility that the operator performs coordinate input on the screen 10 in this state.

In the first place, the cap 46 is adjusted so that the optimum light spot 5 can be obtained on the screen 10 in a standard state through attenuation, diffusion and refraction of the cap 46.
However, if coordinates are input in a state where the camera is not mounted, the amount of light and its distribution are different from the standard state, and the detection accuracy is lowered. In particular, when the coordinates are directly input in a mode in which the tip of the pointing tool 4 is in contact with the screen 10, if the coordinates are input with the cap 46 not attached, the light emitting element 41 is displayed.
May be damaged. As the translucent resin material of the cap 46, for example, even PMMA having the highest total light transmittance (smallest loss) has a 7% loss because the total light transmittance is 93%. Furthermore, surface reflection by processing state,
When diffusion and refraction are added, the loss becomes even greater (the predetermined value TH1 of the PEAK value is usually set based on the state of attachment of the cap 46).

Therefore, when the cap 46 is not attached, the detected light amount increases, and the PEAK value increases. Therefore, FIG.
As shown in FIG. 8, the sensor control unit 31 may perform a detection process of detecting an increase in the PEAK value and detecting non-attachment of the cap 46. Here, when the number of integrations n is smaller than the predetermined number n3 when the predetermined value TH1 is reached, the level control signal PDATA = exHi having an extremely large amount of detected light is used.
Occurs. Next, PDATA = exHi sent to the external control device by the predetermined communication method via the communication control unit 33
The signal is determined to indicate that the cap 46 is not attached, and a display or the like is displayed to prompt the operator to attach the cap. Of course, by processing the level control signal together with the designated area information based on the result of the coordinate calculation processing, the influence of the area may be removed and the processing may be performed more accurately.

According to the other embodiment described above, the mounting state of the cap can be detected on the main unit side without providing any special means to the pointing tool 4, and by notifying the operator of this, It is possible to provide a high-resolution and high-performance coordinate input device by preventing damage to the light-emitting element and deterioration in coordinate detection accuracy due to erroneous input in a state where the light-transmitting member covering the light-emitting element is removed. <Coordinate Value Calculation> Next, coordinate calculation processing in the coordinate calculation unit 32 will be described with reference to FIG.

FIG. 19 is a flowchart showing a coordinate calculation process in the coordinate calculation unit of this embodiment.

The output signals (difference signals from the amplifier 29) of the two linear sensors 20X and 20Y obtained as described above are converted into digital signals by an AD conversion unit 31A provided in the sensor control unit 31 as a coordinate calculation unit. 32,
Coordinate values are calculated. First, the coordinate values are calculated using the X coordinate,
For output data in each direction of the Y coordinate, coordinate values (X1, Y1) on the sensor are obtained. Note that the calculation processing is X,
Since it is the same as Y, only X will be described.

First, in step S202, difference data Dx, which is a difference signal of each pixel at an arbitrary coordinate input point (a predetermined point whose coordinates are known in a reference point setting mode described later).
(N) (the number of pixels n = 64 in this embodiment) is read and stored in a buffer memory (not shown). Next, in step S203, a preset threshold V
And calculates a data value Ex (n) that is equal to or larger than the threshold value.
Using this data value Ex (n), a coordinate X1 on the sensor is calculated in step S204. In the present embodiment, the center of gravity of the output data is calculated by the center of gravity method.
It goes without saying that there are a plurality of calculation methods such as a method of obtaining the peak value of the data value Ex (n) (for example, by a differentiation method).

In step S205, the mode of the coordinate calculation process is determined. In order to calculate coordinates from the center of gravity X1 of the output data, it is necessary to obtain a predetermined value in advance, and a method of deriving the predetermined value (reference point setting mode) will be described.

Similarly, if only the X direction is described,
A point (α1,
In .beta.1) and ([alpha] 2, .beta.2), located a pointing device 4, respectively perform the steps S202 to S204, the centroid value of the X-direction sensor obtained at each point, X1 _1, X1 calculated as _2, the value And the known coordinate values α1 and α2 are stored in step 210. At the time of ordinary coordinate calculation using this stored value, the X coordinate of the coordinate input point to be calculated can be calculated in step S206. In step S207, coordinate values are corrected as needed (for example, the distortion is corrected by a software operation to correct the lens aberration of the optical system) in order to provide a higher-performance coordinate input device. Etc.) to determine the coordinate values.

It is needless to say that the determined coordinates can be output as they are in real time, or data can be thinned out according to the purpose (for example, only one data is output for every ten determined coordinates). However, it is important when the following specifications are assumed.

The stability of the user's hand differs between when the pointing tool 4 is used like a pen and when it is used away from the screen as a pointer. When used as a pointer, the cursor on the screen will tremble finely, so it is easier to use such a fine movement. On the other hand, when used like a pen, it is required to follow as quickly as possible. In particular, when writing a character, if a small quick operation cannot be performed, the input cannot be performed correctly.

In this embodiment, since the ID is transmitted by the control signal, it is possible to determine whether or not the pointer is pressed, that is, whether or not the tip switch is pressed. You can determine whether you are using it. If it is a pointer, for example,
The output coordinate values (X-1, Y-1) and (X
If the current output coordinate value (X, Y) is calculated by calculating a moving average using (−2, Y-2), a configuration with less blur and good operability is obtained. In addition, although a simple moving average is used, other functions used for such a smoothing process include a non-linear compression of the absolute difference value according to the magnitude, and a prediction value based on the moving average. Various methods, such as non-linearly compressing the difference of, can be used.

In other words, if the pointer is used as a pointer, it is possible to increase the level of smoothing, and if not, switch to the level of weakness by means of the control signal. In this regard, the effect of the present invention is great.

Note that, as described above, these calculation processes are performed at 10 m when the coordinate sampling frequency is 100 Hz.
The processing may be completed within sec, and the original data is 64 pixels × 2
The (x and y) × AD conversion unit is as small as 8 bits and does not require any convergence operation, so that a low-speed 8-bit 1-chip microprocessor can perform sufficient processing. This is advantageous not only in terms of cost but also in that specifications can be easily changed, development time can be shortened, and development of various derivative products can be facilitated. In particular, there is no need to develop a dedicated LSI for performing high-speed image data processing as in the case of using an area sensor, and the advantages such as development cost and development period are very large.

The data signal indicating the coordinate value (X, Y) calculated by the above-described calculation processing is supplied to the coordinate calculation unit 32.
Is sent to the communication control unit 33 from. The data signal and the control signal from the control signal detection unit 72 are input to the communication control unit 33. The data signal and the control signal are both converted into a communication signal of a predetermined format,
It is sent to an external display control device. Thus, various operations such as input of a cursor, a menu, characters and line drawings on the screen 10 can be performed. As mentioned above, 6
Even when a 4-pixel sensor is used, a resolution of more than 1000 and sufficient accuracy can be obtained, and both the sensor and the optical system are small,
It is possible to obtain a coordinate input device that can have a low-cost configuration and can have a very small configuration of an arithmetic circuit.

When the sensor is configured as an area sensor, doubling the resolution requires four times the number of pixels and calculation data. On the other hand, when the sensor is configured as a linear sensor, Only needs to double the number of pixels in each of the X and Y coordinates. Therefore, it is easy to increase the number of pixels to achieve higher resolution.

As described above, according to the present embodiment, the peak level of the difference signal obtained from the signals when the pointing device 4 is lit and when it is not lit is detected, and the coordinates are determined according to the peak level value. By calculating the above, it is possible to provide a stable coordinate input device which suppresses the influence of disturbance light, has high resolution and high performance, and can perform control according to the light amount of the light spot.

Further, it is possible to notify the operator of the reduction in the amount of light emission due to the decrease in the current voltage due to the consumption of the power supply unit 44 incorporated in the pointing device 4, and to prompt the exchange and charging of the power supply unit 44.

Further, by controlling the display attribute on the screen 10 according to the light amount of the light spot 5 according to the value of the peak level, the operability is improved and application to various applications becomes possible.

Further, according to the value of the peak level, the mounting state of the cap 46 covering the light emitting element 41 is detected by the indicating tool 4, and the notification is notified, thereby preventing the light emitting element 41 from being damaged and ensuring a stable light quantity. Can be maintained.

The present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and can be applied to a single device (for example, a copying machine, a facsimile machine). Etc.).

Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium includes the above-described storage medium shown in FIGS.
8. The program code corresponding to the flowchart shown in FIG. 19 is stored.

[0109]

As described above, according to the present invention,
It is possible to provide a coordinate input device, a control method thereof, and a computer-readable memory capable of suppressing the influence of disturbance light and enabling high-resolution and high-performance coordinate input.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a coordinate input device according to an embodiment.

FIG. 2 is a diagram showing a detailed configuration of a pointing device of the embodiment.

FIG. 3 is a diagram illustrating an operation mode of the pointing device according to the embodiment.

FIG. 4 is a diagram illustrating a detailed configuration of a coordinate detector according to the present embodiment.

FIG. 5 is a timing chart in a control signal restoring operation of the embodiment.

FIG. 6 is a timing chart of signals handled in the present embodiment.

FIG. 7 is a diagram showing an arrangement relationship between the linear sensors 20X and 20Y of the present embodiment.

FIG. 8 is a diagram showing a detailed configuration of the linear sensor of the present embodiment.

FIG. 9 is a diagram illustrating an example of an output waveform of the linear sensor according to the embodiment.

FIG. 10 is a diagram showing an example of an output waveform for explaining a skim operation of the linear sensor according to the embodiment.

FIG. 11 is a flowchart showing operation control of the linear sensor according to the embodiment.

FIG. 12 is a flowchart illustrating a change process when changing the color of a cursor according to the embodiment;

FIG. 13 is a flowchart illustrating a modification of the operation control of the linear sensor according to the present embodiment.

FIG. 14 is a flowchart illustrating a modification of the change processing when changing the color of the cursor according to the embodiment.

FIG. 15 is a flowchart illustrating a modification of the operation control of the linear sensor according to the embodiment.

FIG. 16 is a flowchart illustrating a modification of the change processing when changing the color of the cursor according to the present embodiment.

FIG. 17 is a diagram showing a detailed configuration when a cap of the pointing device of the present embodiment is attached.

FIG. 18 is a flowchart illustrating a modification of the operation control of the linear sensor according to the present embodiment.

FIG. 19 is a flowchart illustrating a coordinate calculation process in a coordinate calculation unit according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coordinate detector 2 Coordinate detection sensor part 3 Controller 4 Indicator 5 Light spot 6 Light receiving element 6a Condensing lens 7 Signal processing part 8 Projection display device 81 Image signal processing part 82 Liquid crystal panel 83 Lamp 84 Mirror 85 Condenser lens 86 Projection Lens 20X, 20Y Linear sensor 21 Sensor array 22 Integrator 23 Shifter 24 Storage unit 25 Linear CCD 26 Ring CCD 27 Clear unit 28 Skim unit 29 Amplifier 31 Sensor control unit 31A AD conversion unit 32 Coordinate calculation unit 33 Communication control unit 71 Frequency Detector 72 Control signal detector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isao Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Jun Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Masaaki Kinpu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuhide Hasegawa 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. F term (reference) 5B087 AA02 AC09 AE03 BC13 BC19 BC26 BC32 CC09 CC26 CC33 DD06 DE01 DE07

Claims (13)

[Claims] 1. A coordinate input device for irradiating a predetermined position on a coordinate input screen with light from a pointing tool to generate a light spot and generating coordinates corresponding to the light spot, wherein the light spot is detected. Detecting means; detecting means for detecting a lighting state and a non-lighting state of the light spot to calculate a difference signal between a first signal and a second signal; and controlling based on a peak level of the difference signal. Generating means for generating a signal. 2. The coordinate input device according to claim 1, further comprising: display control means for controlling a display attribute of an image displayed based on the light spot based on the control signal. 3. The display attribute includes at least one of a color and a size of a displayed cursor or a color, shading and size of a coordinate image generated corresponding to the light spot. The coordinate input device according to claim 2, wherein 4. A display control means for controlling a display attribute of an image displayed based on the light spot based on the control signal and a coordinate output signal generated corresponding to the light spot. The coordinate input device according to claim 1, wherein: 5. When a light-transmitting member is provided to cover the light-emitting element of the pointing device, the display control means detects a state of attachment of the light-transmitting member to the pointing device based on the control signal. 3. The coordinate input device according to claim 2, further comprising: a detecting unit; and a notifying unit that notifies a mounting state of the translucent member to the pointing tool based on a detection result of the detecting unit. 4. 6. In a case where a light-transmitting member that covers a light-emitting element of the pointing device is provided, the display control unit performs the display control based on the control signal and a coordinate output signal generated corresponding to the light spot. Detecting means for detecting the state of attachment of the translucent member to the indicator, and notifying means for informing the state of attachment of the translucent member to the indicator based on the detection result of the detecting means. 3. The coordinate input device according to claim 2, wherein: 7. A control method of a coordinate input device for generating a light spot by irradiating a predetermined position on a coordinate input screen with light from a pointing device, and generating a coordinate corresponding to the light spot, A detecting step of detecting a lighting state and a non-lighting state of the light spot, wherein the detecting step calculates a difference signal between a first signal and a second signal, and a peak level of the difference signal And generating a control signal based on the control signal. 8. The coordinate input device according to claim 7, further comprising a display control step of controlling a display attribute of an image displayed based on said light spot based on said control signal. Control method. 9. The display attribute includes at least one of a color and a size of a displayed cursor, or a color, a shade and a size of a coordinate image generated corresponding to the light spot. The method for controlling a coordinate input device according to claim 8, wherein 10. A display control step of controlling a display attribute of an image displayed based on the light spot based on the control signal and a coordinate output signal generated corresponding to the light spot. The method for controlling a coordinate input device according to claim 7, wherein: 11. When a light-transmitting member that covers a light-emitting element of the pointing device is provided, the display control step detects a state of attachment of the light-transmitting member to the pointing device based on the control signal. The control of the coordinate input device according to claim 8, further comprising: a detecting step; and a notifying step of notifying a mounting state of the translucent member to the pointing tool based on a detection result of the detecting step. Method. 12. When a light-transmitting member that covers a light-emitting element included in the pointing device is provided, the display control step includes a step of: A detecting step of detecting a mounting state of the translucent member to the pointing device, and a notifying step of notifying a mounting state of the translucent member to the pointing device based on a detection result of the detecting step. 9. The control method for a coordinate input device according to claim 8, wherein: 13. A computer in which a program code for controlling a coordinate input device for generating a light spot by irradiating a predetermined position on a coordinate input screen with light from a pointing tool and storing coordinates corresponding to the light spot is stored. A readable memory, comprising: a program code of a detection step of detecting the light spot; and a difference signal between a first signal and a second signal, which are output by the detection step detecting a lighting state and a non-lighting state of the light spot. A computer readable memory comprising: a program code of a difference step to be calculated; and a program code of a generation step to generate a control signal based on a peak level of the difference signal.