JP2002049469A - Coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coordinate input device prevented from being easily influenced by disturbance light and having a wide dynamic range of light allowed to be received. SOLUTION: In a timing signal generation circuit 200 for generating a binary signal 'IR' in accordance with an output signal from a 2nd light receiving element 4, an output signal from an amplifier 201 is passed through band pass filters(BPFs) 202, 203 having respectively different resonance points and detection processing and smoothing processing are respectively applied to outputs from the BPFs 202, 203 by detection circuits 204, 205 and smoothing circuits 206, 207 having almost the same circuit characteristics to find out two kinds of signals 'V-envel' 'V-enve2'. The output 'V-envel' is binarized by a comparator 211 by using a signal 'V-enve3' corresponding to the signal 'V-enve' as a threshold to extract stable time base information (i.e., the binary signal 'IR') reducing time base variation.

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 example, a coordinate input device for controlling an external device in accordance with coordinates input on a display screen of a large display, or for inputting a pattern such as characters and figures. Related to the device.

Conventionally, there has been proposed a coordinate input device for inputting coordinate information designated by an operator with a pointing device to an external device such as a computer.

As such a coordinate input device, for example, an operator picks up an image of a light spot formed on a display screen of a large display by using a pointing tool by using a CCD area sensor or a linear sensor. A two-dimensional coordinate of the light spot on the display screen is obtained based on an output signal representing the position of the light spot formed on the imaging surface of the sensor, or an analog signal corresponding to the position of the light spot is output. It is known that a plurality of position detecting elements are used to obtain two-dimensional coordinates of the light spot on a display screen based on the magnitude or ratio of the analog voltage output output from the position detecting elements. I have.

In the above-described coordinate input device using light, it is generally required to achieve the following problems.

That is, as a first problem, it is required to eliminate the influence of disturbance light incident on the coordinate input device from the outside in order to generate a coordinate value with high accuracy and perform a stable operation.

[0006] In recent years, display methods of displays have been diversified, the use of infrared rays as wireless communication means has been generalized, or remote control devices using infrared rays have become widespread. There are many infrared rays. Under these circumstances,
In order to accurately perform the original operation as the coordinate input device, means for reliably removing disturbance light is required.

A second problem is that the coordinate input device is required to have a wide dynamic range of light that can be received.

In general, in a coordinate input device of a type that detects light emitted by an operator using an indicator, how the operator handles the indicator (specifically, the direction of the indicator,
The amount of light emitted from the pointing tool greatly changes according to the moving speed and the like. Further, when a battery is used to drive the pointing device, the amount of light emitted from the pointing device greatly changes according to the remaining amount of the battery. Therefore, in such a coordinate input device, light receiving means having a wide dynamic range is required.

[0009]

However, in the above-described coordinate input device of the type which detects a spot light on a display screen, an optical system which passes only light of a specific wavelength band is used as means for removing disturbance light. In addition to providing a filter, little consideration is given to causing the light detection operation of the coordinate input device to follow a fluctuating light amount.

[0010] In a coordinate input device of the type which detects the magnitude or ratio of the analog voltage output of the plurality of position detecting elements, a filter for passing light in a specific wavelength band is used as means for removing disturbance light. In addition, in such a coordinate input device, since the coordinates are detected by using the signal level of the light receiving signal indicating the irradiation light amount, it is almost impossible to follow the fluctuation of the irradiation light amount.

Accordingly, an object of the present invention is to provide a coordinate input device which is hardly affected by disturbance light and has a wide dynamic range of receivable light.

[0012]

In order to achieve the above object, a coordinate input device according to the present invention has the following configuration.

That is, an instruction is provided that includes a modulating means which modulates the lighting period of the blinking light to be emitted by the point light source with a carrier having a frequency sufficiently higher than a predetermined blinking frequency and switches the frequency of the carrier during one lighting period. A coordinate input device for detecting the position of a light spot generated in a predetermined two-dimensional coordinate plane by the light emitted from the tool, and outputting the detected coordinate information; A first light receiving sensor that detects an irradiation position in a two-dimensional direction, a second light receiving sensor that detects a time-series change of light emitted from the light spot, and the light receiving sensor that is detected by the second light receiving sensor. Synchronization control means for synchronizing a detection operation of the first light receiving sensor with a blinking cycle of the light spot based on a time-series change of the light spot; Calculating means for calculating the coordinates of the formation position of the light spot in the two-dimensional coordinate plane based on a signal output from the first light receiving sensor in a state synchronized by the synchronization control means, Detecting the timing at which the modulation frequency is switched during the one lighting period by the indicator, and controlling the detection operation to be synchronized with a synchronization timing shifted by a predetermined time from the detected timing. And

In a preferred embodiment, the synchronization control means converts the electric signal representing the light spot detected by the second light receiving sensor into two kinds of modulation frequencies of the carrier that can be switched during the one lighting period. By passing through first and second band-pass filters having substantially the same resonance frequency as that of the first and second band-pass filters, two types of signals having substantially the same frequency components as the carrier contained in the electric signal are extracted. And the first and second waveform processing circuits.
First and second detection circuits for rectifying two types of signals extracted by the waveform processing circuit, and first and second smoothing circuits for smoothing the two types of signals rectified by the detection circuit. A signal output from the first smoothing circuit, using a threshold generated based on a signal output from the second smoothing circuit, a binary signal for synchronizing the detection operation. It is preferable to include a binarization circuit for converting the signal into a timing signal.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a coordinate input device according to the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
It is a figure explaining the coordinate input system of the coordinate input device in embodiment. FIG. 2 is a block diagram showing a system configuration of the coordinate input device according to the first embodiment of the present invention.

First, the schematic configuration of the coordinate input device according to the present embodiment shown in FIG. 2 will be described with reference to FIG.

The coordinate input device according to the present embodiment is roughly divided into a pointing device 1 for forming a light spot on a screen 2 as a coordinate input surface, and a light beam generated by the pointing device 1 on the screen 2. Light receiving unit 27 for detecting the coordinate position of the light spot 3 and the light receiving unit 2
7 and a signal processing unit 24 for calculating coordinate information based on electrical signals obtained by photoelectrically converting light received by the unit.

FIG. 1 shows an image on a screen 2 and echo back coordinate position information (cursor position, trajectory, etc.) specified by the pointing device 1 in combination with the above-described configuration of the coordinate input device. 1 shows a projection type display device 9 for displaying.

The indicator 1 on the light emitting side includes a light emitting element 15 which is a semiconductor laser or LED for irradiating a light beam, a drive waveform generating circuit 13 for forming a light emitting pattern of the light emitting element, and a drive circuit 14 for driving the light emitting element 15. ,
A switch 11 for inputting additional information such as pen up and down (pen up and pen down) is provided.

Here, the above pen up and down will be described. Originally, when drawing a locus or the like on a piece of paper using a general writing implement (pen) such as a ballpoint pen or a pencil, it is necessary to make the pen touch the paper etc. and move the pen on the paper. The state in which the pen is in contact with the paper surface is expressed as "pen down", and the state in which the pen is moved away from the state in which the pen is in contact with the paper surface is expressed as "pen up". Therefore, an expression similar to that of a general writing instrument is used for an electric pen (that is, an electric device such as the pointing tool 1 handled in the present embodiment).

However, in the case of an electric pen, the trajectory can be drawn and the contact of the pen with the display surface is not necessarily in the same state. Rather, a function switched by a switch (the switch 11 in this embodiment) or the like is used. As "pen down" to be able to draw the locus etc.,
It is accurate recognition that the state other than the above is called "pen-up". Further, in order to improve the convenience of such an electric pen, it is preferable that the position of the pen can be displayed on the display screen with a cursor even in the pen-up state.

The light receiving unit 27 includes a line sensor 7, a cylindrical lens 5 for forming an image of the light spot 3 on the pixel array surface of the line sensor, a line sensor 8, and a light spot 3 on the pixel array surface of the line sensor. The image forming apparatus includes a cylindrical lens 6 for forming an image, and a light receiving element 4 as a second light receiving element.

Here, the line sensor 7 detects the light spot 3
The line sensor 8 detects a position in the X-axis coordinate direction, and a so-called ring CCD (Charge-Couple).
d Device). The line sensors 7 and 8 are controlled by a predetermined timing sequence generated by the control signal generation circuit 21.

The electric signals obtained by the line sensors 7 and 8, which are the first light receiving elements, are converted into digital signals by an analog / digital (AD) conversion unit 20. The CPU 23 calculates the coordinate information of the spot 3 based on the digital signal output from the AD conversion unit 20, and outputs the calculated coordinate information to the computer 26.

The light receiving element 4 of the light receiving unit 27 is a single pixel photoelectric conversion element. The light receiving element 4 has a spot 3
It is a light receiving element for synchronization used for detecting time axis information of light to be irradiated.

The signal output from the light receiving element 4 is subjected to a predetermined band-pass filter in the timing signal generation circuit 200, and the signal output from the band-pass filter is subjected to full-wave rectification, smoothing, and 2
The signal is converted into a signal “IR” by being subjected to the value conversion processing and sent to the control signal generation circuit 21.

The control signal generation circuit 21 determines the input signal "IR" according to a predetermined condition, thereby detecting the incidental information received from the operating tool 1 and detecting the falling timing of the signal "IR" or A rising timing is detected, and a reset signal “RESET” is generated after a lapse of a predetermined time from the timing. This reset signal is sent to the line sensor as a trigger of a timing sequence for controlling the line sensor 7 and 8. This timing sequence is performed once each time the coordinate information for one point of the spot 3 is captured.

Next, each block shown in FIG. 2 will be described in detail.

<Light Emitting Element 15> The drive waveform “LED_dri” of the light emitting element (LED) 15 provided in the pointing device 1
ve "are shown in FIGS. 9 and 15.

"LED-IRCLK" is a signal for giving a blinking cycle of the LED 15, and is set to 7.6 KHz in the present embodiment.

"LED_IR", "LED_IR2"
Is a signal that gives a period during which the LED 15 is turned on, and is a signal in which the above-mentioned “LED_IRCLK” has a predetermined duty. In the present embodiment, in consideration of the light amount and the life of the LED 15, the combined duty is set to 2
5% (lighting time: 33 μS).

"LED_MOD1", "LED_MOD"
“2” is a signal for modulating the above “LED_IR”, and in the present embodiment, “LED_MOD1” is 50
“LED_MOD2” is set to 1 MHz at 0 KHz.

Inside the pointing tool 1, as shown in FIG.
“LED_IR” output from the blinking signal generation circuit 12
Is input to the modulation circuit 13, and the modulation circuit 13 outputs “L”
“LED_MOD1” for “ED_IR”,
The signal modulated by “LED_MOD2” is sent to the LED drive circuit 14.

The modulation circuit 14 can switch the presence or absence of the modulation. In the present embodiment, the first modulation period 25 μS of the lighting period is the first modulation frequency, and the second period 8 μS is the second modulation frequency. A function of switching the carrier frequency during one lighting period of the LED 15 by modulating the frequency is provided. Further, it has a function of controlling the switching operation in accordance with the operation of the operation switch 11 on the pointing device 1.

<Line Sensors 7 and 8> Next, the line sensors 7 and 8 will be described. In the present embodiment, as described above, the circulating accumulation type CCD (ring CC) is used as the line sensors 7 and 8 for detecting the positions in the X and Y coordinate directions.
D) is adopted.

The ring CCD is a kind of line sensor, and is largely different from a general line sensor in that a portion for transferring charges obtained by photoelectric conversion is formed in a circulating type (ring shape). different.

FIG. 3 is a schematic diagram showing the configuration of a ring CCD that can be employed in the first embodiment of the present invention.

For the ring CCD, see, for example,
As shown in US Pat.
A photoelectric conversion unit composed of a plurality of pixels, a circulating charge transfer path composed of m cells arranged in a ring, and a voltage readout unit connected in the middle of the charge transfer path (n = 64 in the present embodiment). , M = 150).

The charge generated by the photoelectric conversion in the photoelectric conversion unit 30 is stored in the storage unit 31. Next, this charge is transferred to the hold unit a or the hold unit b. The accumulation unit 31 discharges the remaining charge before performing the next accumulation (for example, it may be discharged to the ground).
Further, the charge transferred to the hold unit a is sent to the (2i-1) -th order in the cyclic transfer unit 34 in FIG. Similarly, the electric charge transferred to the hold unit b is transferred to the 2i-th charge in the cyclic transfer unit 34.

FIG. 4 shows the i-th photoelectric conversion unit 3 shown in FIG.
FIG. 3 is a diagram showing a portion from 0 to 2i-1 and 2i-th of the cyclic transfer path 34; FIG. 5 is a diagram showing the operation timing of each switch shown in FIG. The movement of this portion is performed using the signal "IRCLK" shown in FIG. 7 as a basic cycle.

Here, the cycle of the signal “IRCLK” is, for example, 7.6 KHz, and the signal “LED_IRCLK” generated by the drive waveform generating circuit 13 of the light emitting unit 1.
Is approximately equal to The signal “IRCLK” is the signal “CCD-C
LK "(for example, 9.12 KHz) divided by 8
The frequency is further divided by 150 (= m).

In this embodiment, the line sensors 7 and 8, which are line CCDs, have a role of an electronic shutter function, and the electronic shutter function is turned on twice in one cycle of the signal "IRCLK". The operation of the electronic shutter function will be described.

FIG. 6 is a timing chart for explaining the electronic shutter function of the ring CCD. One circulation corresponds to one set of electronic shutter operation (two electronic shutter operations).

The details of the electronic shutter function will be described. First, in period C, the charge of the charging unit 31 is changed to SW1.
Cleared by (35). Next, the photoelectric conversion unit 30
Is generated in the charging unit 31 during the period A, and is transferred to the holding unit a when the SW2_1 (36) is turned on during the period E.

In the period D, the charge of the charging unit 31 is cleared by the switch SW1 (35). Next, the current generated in the photoelectric conversion unit 30 is accumulated in the charging unit 31 in the period B, and the current SW2_2 ( 37) is turned on, the data is transferred to the hold section b. The charges held in the holds a and b are simultaneously transferred to the (2i−1) -th and 2i-th cells of the transfer unit 34 during the period G.

In this embodiment, by synchronizing the signal “IRCLK” and the signal “LED_IRCLK”,
In the period A of FIG. 6, the light emitting element (LED) 1 of the pointing device 1
5 emits light and does not emit light in period B. For this reason, the electric charge of the light emitting element 15 when the light is emitted is held in the holding unit a, and the electric charge of the light emitting element 15 when the light emitting element 15 is not emitting light is held in the holding unit b. As a result, the charge at the time of light emission is transferred to the (2i-1) th cell of the transfer unit, and the charge at the time of non-light emission is transferred to the 2i-th cell. The periods A, B,
The operation in each of the periods C, D, E, F, and G is performed simultaneously for all pixels.

Next, the operation of the cyclic transfer unit 34 shown in FIG. 3 will be described. The cyclic transfer unit 34 shown in FIG.
Is the signal "IRCLK" as described with reference to FIG.
The charge circulates in one cycle. Therefore, for example, 2i-1
The charge in the 2i-th cell is the signal “IRCL”
Each cycle of K ″ returns to the same cell. Then, to the charge returned to the original cell, the charge newly held in the holding units a and b is added.
In the present embodiment, the cyclic transfer path 34 includes 150 cells (m = 150). Therefore, the transfer clock “CCD_SP” of the circulating transfer unit 34 has a period of 1/150 of the signal “IRCLK” (1.14 MHz).
z).

The cyclic transfer section 34 is provided with a signal reading section 29 in the middle of the path. In the signal reading unit 29, the electric charge passing through the cyclic transfer unit 34 is
Non-destructive conversion into a voltage value, and the converted voltage value can be read. Further, the difference between the voltage values of two adjacent cells can be read. Therefore, for example, in the 2i-1st and 2ith cells, the hold unit a
And b, the difference between the values of the newly added charges can be read. With this function, in the present embodiment, a voltage signal corresponding to the difference between the accumulated charges when the indicator 1 emits light and when it does not emit light can be read from the signal reading unit 29, The effect of disturbance light can be eliminated.

The signals read from the signal reading unit 29 are read in the same temporal order as the cell arrangement order of the transfer unit 34.

FIG. 5 is a diagram for explaining the output signals of the signal reading section of the ring CCD according to the first embodiment of the present invention. In the example shown in FIG. 5, the order is from the n-th pixel to the first pixel. The voltage value has been read. Here, the high output level in the vicinity of the i-th pixel means that, in the example shown in FIG. 5, the light emitted from the light spot 3 forms an image around the i-th pixel of the sensor pixel array. Show. Therefore, the position where the output level is the highest from the center axis position which is a preset reference position (the i-th pixel in FIG. 5)
By calculating the time lag up to that point, that is, the value of A in FIG. 5, it is possible to obtain the value that is the basis of the X-axis (or Y-axis) coordinate value.

<Control of Ring CCD> Next, control of the above-described ring CCD will be described. In the present embodiment, the X-coordinate and Y-coordinate direction sensors 7 and 8 as ring CCDs take in the coordinate data of one point of the light spot 3 by the timing sequence by the control signal generation circuit 21 as described above. Repeat.

FIG. 7 is a timing chart for explaining a timing sequence for controlling the operation of the ring CCD in the first embodiment of the present invention.

The signals shown in parentheses in the timing charts of FIGS. 6 and 7 are signals generated inside the X-coordinate and Y-coordinate direction sensors 7 and 8 (ring CCDs).
Other signals are signals externally provided to the sensor.

These ring CCDs receive a signal “CCD_
When "RESET" is given, the signal "CCD_SP" is generated by dividing the predetermined timing clock "CCD-CLK" supplied from the control signal generation circuit 21 by 8 using this signal as a trigger, and further generating the signal "CCD_SP". C
By dividing CD_SP by 150, the signal “IR”
CLK ”(therefore, the signal“ IRCLK ”is
This is a signal obtained by dividing the timing clock “CCD-CLK” by 1200). Here, the signal “CCD_SP” is
As described above, this is the transfer clock of the cyclic transfer path 34. Also, as described above, the signal “IRCLK” is 2
ON operation of the electronic shutter and the electric charge of the photoelectric conversion unit 3
This is a reference signal for the operation of transferring from 0 to the cyclic transfer path 34.

First, a signal "LOOP_CL" is supplied to the line CCDs 7 and 8 in synchronization with the signal "IRCLK" from outside.
R ″. This signal allows the cyclic transfer path 3
4 is cleared. Thereafter, in accordance with the signal “IRCLK”, the charge circulating in the circulating transfer path 34 is additionally accumulated in order, and the signal readout unit 2
9, the waveform of the output signal read from V_OUT
(X) gradually increases as indicated by 53 to 58.

The output level of the read waveform V_OUT (X) is monitored by the control signal generation circuit 21.
When this output level reaches a predetermined value (threshold), the signal “CCD_READ” becomes Hi. That is, the ring CCDs 7 and 8 output the signal “CCD_READ” at Lo.
During this period, the accumulation of charges is continued, and when the signal becomes Hi, the accumulation is stopped and only the charge circulation operation is performed (at this time,
The waveform of the signal V_OUT (X) is unchanged).

Thereafter, as indicated by 57 in FIG. 7, the signal "AD_READ" becomes Hi, and accordingly, the analog voltage value V_OUT (X) is changed to the A / D conversion section 20.
After being converted into a digital signal by the CPU, it is sent to the CPU 23.

Here, as described above, the signal “CCD_REA”
D ”is Lo until V_OUT (X) reaches a predetermined value. Therefore, when the signal level is high (when the level of the irradiated light is high),“ CCD_READ ”is Lo.
Is short, and conversely, when the signal level is low (when the level of irradiated light is low), the "CCD
_READ ”is Lo for a long time.
The waveform of the analog voltage taken into the D conversion unit 20 is a voltage waveform of a predetermined level regardless of the level of the signal level of the light actually received by the CCD sensor. Can be taken large.

<Synchronizing Method between Blinking of Light-Emitting Element and Electronic Shutter Function> Next, a method of synchronizing the blinking of the light-emitting element with the electronic shutter function will be described in detail.

In the present embodiment, the light emitting cycle “LED_DRIVE” of the light emitting element 15 of the pointing device 1 is LED_C.
The signal “LED_CLK” generated by the LK generation circuit 12 is divided by 128, which is 7.6 KHz. The frequency of the repetition frequency of the electronic shutter of the ring CCDs 7 and 8 on the light receiving side (one cycle when the shutter is turned on twice) is 7.6 KHz in the signal “IRCLK”.
As described above, this corresponds to a signal obtained by dividing the signal “CCD_CLK” by 1200. That is, the blinking frequency on the light emitting side and the repetition cycle of the electronic shutter on the light receiving side are set to be substantially the same in advance.

Here, as shown in FIG.
The timing sequences of 7 and 8 correspond to the signal “CCD_R
It is designed to start with "ESET".
The signal “IRCLK” generated by the CCD is configured in advance so that the rising timing is immediately after the falling timing of the signal “CCD_RESET”. Therefore, the phase of the signal “IRCLK” can be controlled by controlling the timing of the signal “CCD_RESET”. That is, the signal “IR” obtained by the waveform processing circuit 12 by detecting the light emission of the indicator 1 by the light receiving element 4 is given for a predetermined time T1 (for example, 77.
The signal “CCD_R” is delayed at a timing delayed by 2 μs).
By setting the timing so that “ESET” falls, it is possible to match the phases of “IRCLK” and “LED_IR” at least immediately after the signal “CCD_RESET”, which means that the blinking cycle of the indicator 1 and the This is equivalent to synchronizing the phase of the electronic shutter operation of the ring CCDs 7 and 8.

FIG. 11 is a flow chart showing a process of synchronizing the blinking cycle of the pointing device and the electronic shutter operation of the ring CCD in the first embodiment of the present invention.
The processing executed in the CPU 23 will be described.

As shown in the figure, immediately before the timing sequence starts in step S3, the time is adjusted in step S2, so that the phases of the signals "IRCLK" and "LED_IR" are adjusted at that time, and then the spot 2
During the detection period for one point (that is, until the timing sequence ends), the signals “IRCLK” and “LED_
IR "is free-run. Step S
When the timing sequence 3 is completed, the process returns to step S1 to enter a state of waiting for detection of the falling timing of the signal “CCD_RSET”. Then, when the first falling timing is detected, the time is adjusted again (waiting for a predetermined time T1) to adjust the phases, and then the next timing sequence is started.

Here, what should be considered is a frequency deviation between the signals “IRCLK” and “LED_CLK” during execution of the timing sequence (free-run period). Hereinafter, the frequency deviation will be described.

In this embodiment, the period at which the coordinates of one point of the light spot 3 are captured by the ring CCDs 7 and 8 is set to 40 ms at the maximum. This is because the cycle of the signal “CCD_RESET” shown in FIG.
ms, which means that the free-run period is at most 40 ms.

In the present embodiment, the LED_
CLK generation circuit 12 and C of signal processing unit 24
The CD-CLK generation circuit 22 is based on the assumption that a general crystal oscillator is used. The frequency accuracy of a general quartz oscillator is better than 100 ppm. Here, for example, assuming that the frequency accuracy of the crystal unit is 100 ppm, the phase deviation that can occur during the free run is:
40 ms × 100 ppm = 4 μs, and this value is sufficiently smaller than the period (131.6 μs) of the signal “IRCLK” or its lighting period (Hi period) as compared with 25 μs.

Therefore, even during the free-run period,
The signals “IRCLK” and “LED_IR” can be substantially synchronized, and the synchronization operation between the indicator 1 and the light receiving side can be realized wirelessly.

<Switch 11 of Pointing Tool 1> The pointing tool 1 is provided with a switch (SW) 11 as shown in FIG. Can be used to Hereinafter, a method of causing the light receiving unit 27 to recognize the operation of the switch 11 will be described.

In this embodiment, the drive signal “LED_DR”
The lighting period when the light-emitting element 15 blinks due to IVE "is configured to be entirely or partially modulated by a carrier having a frequency sufficiently higher than the blinking frequency. Since only the modulated portion is detected by the light receiving element 4, only the modulated portion has meaning as time axis information.

Therefore, in the present embodiment, when the switch 11 on the pointing device 1 is pressed, the drive waveform generating circuit 13 modulates the signal “LED_IRCLK” every other time, thereby obtaining the signal shown in FIG. Is output to the drive circuit 14, and when the switch 11 is not pressed, modulation is performed for each cycle of the signal "LED_IRCLK" as shown in FIG.

When the signal emitted by the light emitting element 15 in the light emitting pattern configured as described above is received by the ring CCDs 7 and 8, the same cycle (T2) regardless of whether the switch 11 is pressed or not pressed. ) Is detected as a blinking signal, and when received by the light receiving element 4, the signal "LED_IRCLK" is detected as blinking every other time (or at a cycle of T2 × 2). You. That is, the coordinate detection by the ring CCDs 7 and 8 is as follows.
In either case, the same operation is performed, and one bit of information is transmitted to the light receiving unit 27 as an output signal of the light receiving element 14 without affecting the blinking of the light emitting element 15 and the synchronous operation of the electronic shutter function. The state of the operation switch 11 can be detected.

<Timing signal creation circuit 200>
The features and purpose of the timing signal generation circuit 200 will be described in comparison with a case where the timing signal generation circuit 150 having another configuration is adopted.

FIG. 8 is a block diagram showing the internal configuration of another timing signal generating circuit, and FIG. 16 shows the signal flow in this circuit.

In FIG. 8, an optical signal (electric signal) photoelectrically converted by the light receiving element 4 is amplified to a predetermined level by an amplifier 61, and the amplified signal is transmitted to the indicator (light emitting unit) 1 side. The light passes through a band-pass filter 62 having a resonance frequency characteristic having substantially the same frequency as “LED_CLK”. The signal that has passed through the filter is subjected to general full-wave rectification, smoothing, and binarization processing in a detection circuit 63, a smoothing 64, and a binarization circuit 65, so that the signal “IR” is obtained. And sent to the control signal creation circuit. In this type of circuit, the smoothed envelope signal (V-env0 in FIG. 8) produces a "who" with a time constant τ0. The magnitude of V-enve0 is determined by the amplifier 61
, Which is proportional to the amplitude of the original signal, ie, the intensity of the incident light.

Therefore, in this type of circuit, when the light receiving signals having different signal levels are binarized by a fixed threshold value Vth_0 as shown in FIG. The degree of influence on Accordingly, when the binarized timing signal IR has, for example, the level difference shown in FIG. 16, the time variation of (ΔT−e) at the rising timing and (ΔT−b) at the falling timing. Occurs.

Therefore, in the present embodiment, the aim is to eliminate the time variation due to the level difference so as to suppress the influence of “who” almost uniformly. The configuration and operation of the timing signal generation circuit 200 are as follows. Will be described.

FIG. 14 is a block diagram showing the configuration of the timing signal generation circuit 200 according to the first embodiment.

As described above, in the present embodiment, the infrared rays radiated from the pointing device 1 are received by the line sensors 7 and 8 as the first light receiving elements, so that the infrared rays radiated from the pointing device 1 are received. The direction is detected, and the infrared light is also received by the light receiving element 4 as the second light receiving element, so that time axis information included in the received infrared light is acquired. The light emitting unit on the first side is synchronized with the electronic shutter function of the light receiving unit 27 on the main body side (the signal processing unit 24 side), and information corresponding to the operation of the switch 11 of the pointing tool 1 is detected.

An optical signal (FIG. 15, “LED-drive”) obtained by photoelectric conversion in the second light receiving element.
Vrf is amplified to a predetermined level in the amplifier 201, and the amplified signal Vrf-a output from the amplifier 201 is almost the same as the above-mentioned light-emitting side modulation signals “LED_MOD1” and “LED_MOD2”. Bandpass filter 20 having the same frequency resonance point
2 and 203, the signals “Filter-out1” and “Filter-out1” shown in FIG.
2 ". Here, the band-pass filters 202 and 20 are obtained.
The resonance point 3 is 500 KH in the present embodiment.
z, the latter is 1 MHz.

The signal “Filter-out 1” output from the band-pass filter 202 is rectified by the detection circuit 204 into a signal “Detec-out 1”. env
e1 ”and the signal“ V-enve1 ”.
Is input to a comparator (binarization circuit) 211. on the other hand,
The signal “Fil” output from the bandpass filter 203
ter-out2 ”is detected by a signal“ De
The signal is rectified to “tec-out2”, and the signal passes through the smoothing circuit 207 to become a signal “V-enve2”. Here, the detection circuits 204 and 205 have almost the same characteristics, and the smoothing circuits 206 and 207 May have substantially the same characteristics.

Further, for the output “V-enve2”, the coefficient adder 208 outputs a coefficient A1 (V-enve1 and V-enve1).
As a coefficient for compensating the amplitude ratio of -enve2, for example, A
1 = 1), and a predetermined voltage “V-bottom” output from the constant voltage circuit 209 and “V-feedba” output from the attenuator 210 according to the binary signal “IR”.
ck "is added, the comparator (binarization circuit)
An output “V-enve3” to 211 is created, and this output “V-enve3” is used as a binarization threshold of the comparator 211. Here, the predetermined voltage “V-boto”
m ”is added to the output“ V-enve2 ”to facilitate the detection of the rising edge.
0 output “V-feedback” and output “V-env”
The reason for adding to e2 ″ is to prevent oscillation and chattering.

As described above, in the present embodiment, the comparator 211
, The output “V-enve1” of the smoothing circuit 206
From the output signal “V-enve3” based on the output signal “V-enve2” of the smoothing circuit 207 as a threshold value.
The binarization signal “IR” in which the time variation due to the level difference of the light received by the second light receiving element 4 is suppressed is created.

As described above, according to the present embodiment, the coordinate input device is provided with the ring CCDs 7 and 8 as light receiving elements, and by controlling these ring CCDs from outside, an electronic shutter function is realized. The function was synchronized with the flashing cycle of the light emission of the indicator 1.
As a result, it is possible to eliminate the influence of malfunction or the like due to disturbance light.

Further, in the present embodiment, the state in which the charge generated in the photoelectric conversion unit 30 is circulated while accumulating sequentially and the state in which only the circulation is performed without performing additional accumulation are performed by the control signals supplied to the ring CCDs 7 and 8. And the switching of the state is performed according to the amount of light emitted from the pointing device 1. For example, when light having a low light receiving level is received, the charge corresponding to the received light is charged. When the ring CCD accumulates a large number of times, and when light having a high light receiving level is received, a charge corresponding to the received light is accumulated a small number of times in the ring CCD. Accordingly, accurate coordinate detection can be performed even when the irradiation light amount fluctuates, and the dynamic range of light that can be received can be widened.

In the present embodiment, the light receiving unit 27
Although the indicator (light emitting unit) 1 and the light receiving unit 27 are configured wirelessly by taking timing according to the signal obtained from the light receiving element 4, the blinking cycle of the indicator 1 and the ring CCD 7 in the light receiving unit 27 8
The electronic shutter function can be synchronized. That is, in the present embodiment, each time the coordinate data for one point is processed, the ring CCD 7 based on the leading or trailing end of any one emission pulse of the blinking signal detected by the light receiving element 4 is used as a reference. And the start of the timing sequence for controlling the operations 8 and 8, it is possible to synchronize the blinking of the indicator 1 with the electronic shutter function of the light receiving unit 27, to suppress the influence of disturbance light, and to achieve high precision and high resolution. Two-dimensional coordinate values can be obtained.

Further, in this embodiment, the light emission signal on the light emission side not only blinks at a predetermined cycle, but also performs a simple modulation with a carrier having a frequency sufficiently higher than the blinking frequency at the time of the light emission. By passing the signal received at 4 through a band-pass filter having a resonance point at substantially the same frequency as that of the carrier, it is possible to extract only the frequency component substantially the same as that of the carrier contained in the received light signal. . Thereby, also in the light receiving element 4, the influence of disturbance light can be eliminated.

Further, in this embodiment, the timing signal generating circuit 200 for generating the binary signal "IR" in accordance with the output signal of the second light receiving element 4 has a resonance point at substantially the same frequency as the above carrier frequency. A plurality of band pass filters 202 and 203 are provided, and outputs of the band pass filters are separately detected by detection circuits 204 and 20 respectively.
7, and detection in the smoothing circuits 206 and 207,
After performing smoothing, two types of envelope waveforms “V-enve1” and “V-enve2” obtained from them (strictly, “V-enve3” based on “V-enve2”)
Are generated and binarized by the comparator 211 based on the envelope waveforms, thereby extracting stable time-axis information with little time-axis fluctuation (that is, binarized signal “IR”). it can. This makes it possible to secure a wide dynamic range for infrared rays emitted from the pointing device 1 to the light receiving unit 27 irrespective of noise due to disturbance light. Can be stabilized.

Therefore, according to the coordinate input device of the present embodiment, the information by the switch operation of the pointing device 1 can be accurately detected on the main body side (the light receiving unit 27 and the signal processing unit 24), and various kinds of information can be detected. Under the environment,
Alternatively, even when the handling of the pointing tool 1 by the operator is rough, stable coordinate input can be performed.

[Second Embodiment] Next, the second embodiment of the present invention will be described based on the apparatus configuration in the first embodiment.
An embodiment will be described. In the following description, the description of the same parts as in the first embodiment will be omitted, and the description will focus on the characteristic parts in the present embodiment.

FIG. 12 is a block diagram showing a system configuration of a coordinate input device according to the second embodiment of the present invention.

In the present embodiment, a signal "IR" is sent from the timing signal generating circuit 200 to the control signal generating circuit 21 in the same manner as in the first embodiment, and a PLL (IR) is generated based on the signal "IR". The signal “IR_P” generated by the PHASE LOCK LOOP 72 is
(See FIG. 13).

The timing signal generation circuit 200 converts the signal received by the second light-receiving element 4 for synchronization into band-pass filters 202 and 203 (which have a resonance circuit having the same frequency as the carrier frequency described in the first embodiment). FIG.
) To remove disturbance light.
In a general use environment, disturbance light can be sufficiently removed. However, in an environment where extremely large disturbance light, which is far more than expected, is incident, it may not be possible to completely eliminate the influence. In such a case, the output of the bandpass filter 202, “F
For example, in FIG.
When the influence of this noise is taken in at the beginning or end of the signal “IR”, the control signal creation circuit 21 outputs the signal “IR”.
May be erroneously recognized at the beginning or at the end. However, these whisker-like noises output from the bandpass filter have little energy with respect to the original output signal from the bandpass filter. Therefore, in the present embodiment, the signal “IR_PL” is output from the PLL 72 having a general configuration in accordance with the signal “IR” output from the timing signal generation circuit 200.
By generating L ", such an adverse effect is avoided.

According to the coordinate input device of the second embodiment having such a device configuration, not only effects similar to those of the coordinate input device of the first embodiment are obtained, but also more accurate operation is realized. be able to.

[0095]

As described above, according to the present invention,
Thus, it is possible to provide a coordinate input device that is hardly affected by disturbance light and has a wide dynamic range of light that can be received.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a coordinate input system of a coordinate input device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a system configuration of the coordinate input device according to the first embodiment of the present invention.

FIG. 3 shows a ring C that can be employed in the first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration of a CD.

4 is a diagram showing a portion from an i-th photoelectric conversion unit 30 shown in FIG. 3 to 2i-1 and 2i-th of a cyclic transfer path 34. FIG.

FIG. 5 is a ring CCD according to the first embodiment of the present invention;
FIG. 4 is a diagram illustrating an output signal of a signal reading unit of FIG.

FIG. 6 is a timing chart illustrating an electronic shutter function of a ring CCD.

FIG. 7 shows a ring CCD according to the first embodiment of the present invention;
3 is a timing chart for explaining a timing sequence for controlling the operation of FIG.

FIG. 8 is a block diagram showing an internal configuration of another timing signal generation circuit 150.

FIG. 9 is a timing chart illustrating drive waveforms of the light emitting device according to the first embodiment of the present invention.

FIG. 10 is a diagram illustrating a drive signal on the light emitting side and an output signal of the timing signal generation circuit 100 according to the first embodiment of the present invention.

FIG. 11 is a flowchart showing a process of synchronizing the blinking cycle of the pointing device and the electronic shutter operation of the ring CCD according to the first embodiment of the present invention.

FIG. 12 is a block diagram illustrating a system configuration of a coordinate input device according to a second embodiment of the present invention.

FIG. 13 is a diagram illustrating a drive signal on the light emitting side and an output signal of the timing signal generation circuit 100 according to the second embodiment of the present invention.

FIG. 14 is a block diagram illustrating a circuit configuration of the timing signal generation circuit 100 according to the first embodiment of the present invention.

FIG. 15 is a timing chart illustrating the operation of the timing signal generation circuit 100 according to the first embodiment of the present invention.

16 is a timing chart illustrating an operation of the timing signal generation circuit 150 shown in FIG.

Continued on the front page F term (reference) 2F065 AA03 AA19 BB29 DD04 DD11 FF24 GG06 GG07 GG12 JJ01 JJ05 JJ25 LL08 MM28 NN02 NN08 NN11 NN20 QQ03 QQ04 QQ08 QQ23 QQ25 QQ32 QQ33 QQ34 5B068 AA A02 A02 A02 A02 BC BC17 CC09 CC26 CC33 DD02 DG02 DJ03

Claims (7)

[Claims] 1. A modulation method for modulating a lighting period of blinking light to be emitted by a point light source by a carrier having a frequency sufficiently higher than a predetermined blinking frequency, and switching a frequency of the carrier during one lighting period of the point light source. A coordinate input device for detecting a position of a light spot generated in a predetermined two-dimensional coordinate plane by light emitted by a pointing tool having a means, and outputting the detected coordinate information, and irradiating from the light spot. A first light receiving sensor that detects a two-dimensional irradiation position of the light to be irradiated, a second light receiving sensor that detects a time-series change of light irradiated from the light spot, and the second light receiving sensor Synchronization control means for synchronizing a detection operation of the first light receiving sensor with a blinking cycle of the light spot based on the detected time-series change of the light spot; Calculating means for calculating the coordinates of the formation position of the light spot in the two-dimensional coordinate plane based on a signal output from the first light receiving sensor synchronized by the control means; The means detects a timing at which a modulation frequency is switched during the one lighting period by the indicator, and controls the detection operation to be synchronized with a synchronization timing shifted by a predetermined time from the detected timing. A coordinate input device. 2. The synchronization control means according to claim 1, wherein the synchronization control means converts the electric signal representing the light spot detected by the second light receiving sensor to substantially the same as two kinds of modulation frequencies of the carrier that can be switched during the one lighting period. First and second waveform processing circuits for extracting two kinds of signals having substantially the same frequency components as the carrier contained in the electric signal by passing through first and second band-pass filters having a resonance frequency. And 2 extracted by the first and second waveform processing circuits.
First and second detection circuits for rectifying the types of signals, first and second smoothing circuits for smoothing the two types of signals rectified by the detection circuits, and the first smoothing circuit. The output signal is determined by the second
Using a threshold value generated based on a signal output from the smoothing circuit of the present invention to convert to a binary timing signal for synchronizing the detection operation. Item 3. The coordinate input device according to Item 1. 3. The coordinate input device according to claim 1, wherein the first light receiving sensor is two line sensors arranged in two directions that are not parallel to each other. 4. The device according to claim 1, wherein the line sensor includes a photoelectric conversion element,
A ring CCD having a ring-shaped charge transfer path capable of accumulating charges generated in the element while sequentially adding the charges, wherein the synchronization control means synchronizes with the ring CCD in synchronization with a blinking cycle of the light spot. And causing the photoelectric conversion element to perform photoelectric conversion, and accumulates charges generated by the conversion while circulating through the charge transfer path and sequentially adding the charges in synchronization with the blinking cycle. The electric charge accumulated in the charge transfer path is sequentially read out as an electric signal, and coordinates of a formation position of the light spot in the two-dimensional coordinate plane are calculated based on a difference between the read electric signals. Item 3. The coordinate input device according to Item 3. 5. The synchronization control means according to claim 1, wherein a period of accumulating the charge generated in the photoelectric conversion element in the charge transfer path is sequentially changed according to a light amount of the light spot. Item 4. The coordinate input device according to Item 4. 6. The synchronization control means, each time one point of the coordinates of the light spot is processed, based on a time-series change of the light spot detected by the second light receiving sensor. 4. The method according to claim 1, wherein a start timing or an end timing of one lighting period in a blinking period is detected, and a detection operation by the first light receiving sensor is synchronized with a synchronization timing shifted by a predetermined time from the detected timing. Item 6. The coordinate input device according to any one of Items 5. 7. The pointing device further includes an operation switch, and modulation control means for controlling the presence / absence of modulation by the modulation means in accordance with the operation of the switch. Detecting means for detecting an operation state of the switch by determining whether or not there is modulation by the modulation means based on a time-series change of an electric signal representing the light spot detected by the light receiving sensor. The coordinate input device according to claim 1, wherein: