JP4266446B2 - Coordinate input device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coordinate input device, and for example, relates to a coordinate input device that controls an external device according to coordinates input on a display screen of a large display or inputs a pattern such as a character or a figure.
[0002]
[Prior art]
Conventionally, there has been proposed a coordinate input device that inputs coordinate information instructed by an operator to an external device such as a computer.
[0003]
As such a coordinate input device, for example, an image of a light spot formed on a display screen of a large display by an operator using an indicator is captured by using a CCD area sensor or a linear sensor. A plurality of positions at which two-dimensional coordinates on the display screen of the light spot are obtained based on an output signal representing the position of the light spot imaged in the plane, or an analog signal corresponding to the position of the light spot is output A device that uses a detection element to obtain a two-dimensional coordinate on the display screen of the light spot based on the magnitude or ratio of analog voltage output output from those position detection elements is known.
[0004]
In the above-described coordinate input device using light, it is generally required to achieve the following problems.
[0005]
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 highly accurate coordinate values and perform stable operation.
[0006]
In recent years, diversification of display methods, generalization of the use of infrared rays as wireless communication means, or remote control devices using infrared rays have become widespread, and there are many environments where coordinate input devices are used. Infrared is present. Under such circumstances, in order to accurately perform the original operation as the coordinate input device, means for reliably removing ambient light is required.
[0007]
As a second problem, the coordinate input device is required to have a wide dynamic range of light that can be received.
[0008]
In general, in a coordinate input device of a type that detects light emitted by an operator with an indicator, depending on how the operator handles the indicator (specifically, the direction of the indicator, the moving speed, etc.), The amount of light emitted from the pointing tool varies greatly. Further, when a battery is used to drive the pointing tool, the amount of light emitted from the pointing tool varies greatly depending on the remaining amount of the battery. Therefore, in this type of coordinate input device, a light receiving means having a wide dynamic range is required.
[0009]
[Problems to be solved by the invention]
However, in the coordinate input device of the type that detects spot light on the display screen described above, an optical filter that passes only light of a specific wavelength band is provided as means for removing disturbance light, and the coordinate input is performed. Almost no consideration is given to making the light detection operation by the apparatus follow the changing irradiation light quantity.
[0010]
Also, in the coordinate input device of the type that detects the magnitude or ratio of the analog voltage output of the plurality of position detection elements described above, a filter that passes light in a specific wavelength band is provided as means for removing disturbance light. In such a type of coordinate input device, the coordinates are detected by using the signal level of the received light signal that indicates the amount of irradiation light, so that it is impossible to follow the variation in the amount of irradiation light.
[0011]
Therefore, the present invention provides a first coordinate input device that detects the coordinate position of a light spot generated in a predetermined two-dimensional coordinate plane with high accuracy and high resolution by suppressing the influence of disturbance light. Objective.
[0012]
Furthermore, a second object of the present invention is to provide a coordinate input device having a wide dynamic range of light that can be received.
[0013]
[Means for Solving the Problems]
In order to achieve the above first object, a coordinate input device according to the present invention is characterized by the following configuration.
[0014]
Immediately The finger Indicator The light was emitted at a predetermined flashing cycle from By light Instructions A coordinate input device that detects a position and outputs the detected coordinate information, Light emission This Light A first light receiving sensor to detect; Light emission This The Time series of light of A second light receiving sensor for detecting a change, and the second light receiving sensor detected by the second light receiving sensor. Of emitted light Time series of Based on the change, Of emitted light Based on the synchronization control means for synchronizing the detection operation of the first light receiving sensor with respect to the blinking cycle, and the signal output from the first light receiving sensor in a state synchronized by the synchronization control means, Instructions And calculating means for calculating the coordinates of the position.
[0015]
Preferably, two line sensors arranged in two directions that are not parallel to each other may be employed as the first light receiving sensor.
[0016]
Further, for example, when a ring CCD having a photoelectric conversion element and a ring-shaped charge transfer path capable of accumulating while sequentially adding charges generated in the element is employed as the line sensor, the synchronization control is performed. Means for the ring CCD; Of emitted light The photoelectric conversion element performs photoelectric conversion in synchronization with the blinking cycle, and the charge generated by the conversion is accumulated while being circulated through the charge transfer path and sequentially added in synchronization with the blinking cycle. The means sequentially reads out the electric charge accumulated in the charge transfer path as an electric signal, and based on the difference between the read electric signals, Instructions It is good to calculate the coordinates of the position.
[0017]
In order to achieve the second object, in the coordinate input device having the above-described configuration, the synchronization control means includes Of emitted light In accordance with the amount of light, the accumulation period may be changed while sequentially adding the charges generated in the photoelectric conversion elements in the charge transfer path.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a coordinate input device according to the present invention will be described in detail with reference to the drawings.
[0019]
[First Embodiment]
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.
[0020]
First, a schematic configuration of the coordinate input device in the present embodiment shown in FIG. 2 will be described with reference to FIG.
[0021]
The coordinate input device according to the present embodiment is roughly divided into an indicator 1 that forms a light spot on the screen 2 that is a coordinate input surface, and a light spot that is generated on the screen 2 by light emitted by the indicator 1. And a signal processing unit 24 for calculating coordinate information based on an electric signal obtained by photoelectric conversion of the light received by the control of the light receiving unit 27 and the light received by the unit. .
[0022]
In FIG. 1, together with the above-described configuration of the coordinate input device, an image is displayed on the screen 2 and the coordinate position information (cursor position, locus, etc.) indicated by the pointing tool 1 is echoed back and displayed. A projection type display device 9 is shown.
[0023]
The indicator 1 on the light emitting side includes a light emitting element 15 that is a semiconductor laser or LED that emits a light beam, a drive waveform generating circuit 13 that creates a light emission pattern of the light emitting element, a drive circuit 14 that drives the light emitting element 15, and a pen-up. A switch 11 for inputting incidental information such as down (pen-up and pen-down) is provided.
[0024]
Here, the above pen up / down will be described. Originally, when drawing a locus or the like using a general writing instrument (pen) such as a ballpoint pen or pencil on paper, it is necessary to bring the pen into contact with the paper and move the pen on the paper surface. The state where the pen is brought into contact with the paper surface is expressed as “pen down”, and the state where the pen is moved away from the state where the pen is brought into contact with the paper surface is expressed as “pen up”. Therefore, an expression similar to that of a general writing tool is used for an electric pen (that is, an electric device such as the pointing tool 1 handled in the present embodiment).
[0025]
However, in an electric pen, drawing a locus and contacting the pen with the display surface are not necessarily in the same state, but rather as a function switched by a switch (switch 11 in the present embodiment) or the like. The correct recognition is to call “pen down” when the image is in a state in which it can be drawn, and “pen up” when it is not. Further, in order to improve the convenience of such an electric pen, it is preferable that the cursor position can be displayed on the display screen even in the pen-up state.
[0026]
The light receiving unit 27 forms an image of the light spot 3 on the line sensor 7, the cylindrical lens 5 that forms an image of the light spot 3 on the pixel array surface of the line sensor, the line sensor 8, and the pixel array surface of the line sensor. A cylindrical lens 6 and a light receiving element 4 as a second light receiving element are provided.
[0027]
Here, the line sensor 7 is a so-called ring CCD (Charge-Coupled Device) that detects the position of the light spot 3 in the X-axis coordinate direction, and the line sensor 8 detects the position in the Y-axis coordinate direction. The line sensors 7 and 8 are controlled by a predetermined timing sequence created by the control signal creation circuit 21.
[0028]
The electric signals obtained by the line sensors 7 and 8 as 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.
[0029]
The light receiving element 4 of the light receiving unit 27 is a single-pixel photoelectric conversion element. The light receiving element 4 is a synchronizing light receiving element used for detecting time axis information of light emitted from the spot 3.
[0030]
The signal output from the light receiving element 4 is subjected to a predetermined band pass filter in the waveform processing circuit 19, and the signal output from the band pass filter is subjected to general full wave rectification, smoothing, and binarization processing. As a result, the signal “IR” is generated and sent to the control signal generation circuit.
[0031]
The control signal generation circuit 21 detects the incidental information received from the operation tool 1 by determining the input signal “IR” according to a predetermined condition, and sets the falling timing or rising timing of the signal “IR”. A reset signal “RESET” is generated after a predetermined time has elapsed from the detection. This reset signal is sent to the line sensor as a trigger of a timing sequence for controlling the line sensors 7 and 8. This timing sequence is performed once every time coordinate information for one point of the spot 3 is captured.
[0032]
Next, each block shown in FIG. 2 will be described in detail.
[0033]
<Light emitting element 15>
FIG. 9 is a timing chart for explaining the drive waveform of the light emitting element in the first embodiment of the present invention, and the drive waveform of the light emitting element 15 is indicated by “LED_DRVE”.
[0034]
In the drive waveform generation circuit 13 of the light emitting unit 1, a signal “LED_IRCLK” obtained by dividing the predetermined “LED_CLK” (for example, 972.8 KHz) output from the LED_CLK generation circuit 12 by, for example, 128 is generated. “LED_IR” is a signal having the same cycle as “LED_IRCLK” and a different predetermined duty (for example, the period of Hi is 33 ms). The signal “LED_DRIVE” is a drive signal output from the drive circuit 14 to the light emitting element 15, and is generated by gating “LED_CLK” with the signal “LED_IR”.
[0035]
<Waveform processing circuit 19>
FIG. 8 is a block diagram showing the internal configuration of the waveform processing circuit according to the first embodiment of the present invention.
[0036]
In the figure, an optical signal (electrical signal) photoelectrically converted by the light receiving element 4 is amplified to a predetermined level by an amplifier 61, and the amplified signal is “LED_CLK” on the indicator (light emitting unit) 1 side. And a band-pass filter 62 having a resonance frequency characteristic of substantially the same frequency. Then, the signal that has passed through the filter is subjected to general full-wave rectification, smoothing, and binarization processing in the detection circuit 63, smoothing 64, and binarization circuit 65, whereby the signal "IR" And sent to the control signal generation circuit. The output signal “FILTER_OUT” of the band pass filter 62 is shown in FIG.
[0037]
As described above, the optical signal “LED_IR” emitted from the light emitting element 15 of the light emitting unit (indicator) 1 is reproduced as the signal “IR” in the signal processing unit 24. Here, the signal waveform of the signal “IR” is slightly delayed in both the rising timing and the falling timing due to the influence of the phase characteristics of the bandpass filter 62 and the smoothing circuit 64 in the waveform processing circuit 19 (this book) In the embodiment, the signal “IR” has the same delay as “LED_IR”.
[0038]
<Line sensors 7 and 8>
Next, the line sensors 7 and 8 will be described. In the present embodiment, as described above, the circulation accumulation type CCD (ring CCD) is employed as the line sensors 7 and 8 for detecting the positions in the X and Y coordinate directions.
[0039]
The ring CCD is a kind of line sensor, and is greatly different from a general line sensor in that a portion for transferring charges obtained by photoelectric conversion is formed in a circulation type (ring shape).
[0040]
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.
[0041]
With respect to the ring CCD, for example, as disclosed in JP-A-8-233571, a photoelectric conversion unit composed of n pixels arranged in a line, a circulating charge transfer path composed of m cells arranged in a ring, A voltage readout unit connected in the middle of the charge transfer path is provided (in this embodiment, n = 64 and m = 150).
[0042]
The charges generated by the photoelectric conversion in the photoelectric conversion unit 30 are accumulated in the accumulation unit 31. Next, this electric charge is transferred to the hold part a or the hold part b. Further, the storage unit 31 discharges the remaining charge before performing the next storage (for example, it may be discharged to the ground). Further, the charge transferred to the hold unit a is sent to the 2i-1th of the cyclic transfer unit 34 in FIG. Similarly, the charge transferred to the hold unit b is transferred to the 2i-th of the cyclic transfer unit 34.
[0043]
FIG. 4 is a diagram illustrating portions from the i-th photoelectric conversion unit 30 illustrated in FIG. 3 to the 2i-1 and 2i-th portions of the cyclic transfer path 34. FIG. 5 is a diagram showing the operation timing of each switch shown in FIG. Further, the movement of this portion is performed using the signal “IRCLK” shown in FIG. 7 as a basic period.
[0044]
Here, the cycle of the signal “IRCLK” is, for example, 7.6 KHz, and is substantially equal to the signal “LED_IRCLK” generated by the drive waveform generation circuit 13 of the light emitting unit 1. The signal “IRCLK” is a signal “CCD-CLK” (for example, 9.12 KHz) divided by 8 and further divided by 150 (= m).
[0045]
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 this electronic shutter function will be described.
[0046]
FIG. 6 is a timing chart for explaining the electronic shutter function of the ring CCD, and one cycle corresponds to one set of electronic shutter operations (two electronic shutters).
[0047]
Details of the electronic shutter function will be described. First, in period C, the charge of the charging unit 31 is cleared by SW1 (35). Next, the current generated in the photoelectric conversion unit 30 is accumulated in the charging unit 31 in the period A, and is transferred to the hold unit a when the SW2_1 (36) is turned on in the period E.
[0048]
In addition, the charge of the charging unit 31 is cleared by SW1 (35) in the period D, and then the current generated in the photoelectric conversion unit 30 is accumulated in the charging unit 31 in the period B, and SW2_2 (37) is stored in the period F. When it is turned on, it is transferred to the hold unit b. The charges held in the holds a and b are simultaneously transferred to the 2i−1 and 2i cells of the transfer unit 34 in the period G.
[0049]
In the present embodiment, by synchronizing the signal “IRCLK” and the signal “LED_IRCLK”, the light emitting element (LED) 15 of the indicator 1 emits light in the period A of FIG. For this reason, the charge at the time of light emission of the light emitting element 15 is held in the hold part a, and the charge at the time of non-light emission of the light emitting element 15 is held in the hold part b. As a result, the charge at the time of light emission is transferred to the 2i-1st cell of the transfer unit, and the charge at the time of non-light emission is transferred to the 2ith cell. The operations in the periods A, B, C, D, E, F, and G described above are performed simultaneously for all the pixels.
[0050]
Next, the operation of the circular transfer unit 34 shown in FIG. 3 will be described. As described with reference to FIG. 6, the cyclic transfer unit 34 shown in FIG. 6 circulates charges once in one cycle of the signal “IRCLK”. Therefore, for example, the charges in the 2i-1st and 2ith cells return to the same cell for each cycle of the signal “IRCLK”. Then, the charges newly held in the hold units a and b are added to the charges returned to the original cell. In the present embodiment, the cyclic transfer path 34 is composed of 150 cells (m = 150). Therefore, the transfer clock “CCD_SP” of the circular transfer unit 34 has a period (1/14 MHz) that is 1 / 150th of the signal “IRCLK”.
[0051]
Further, the cyclic transfer unit 34 is provided with a signal reading unit 29 in the middle of the path. The signal reading unit 29 can convert the electric charge passing through the circulation type transfer unit 34 into a voltage value in a non-destructive manner and read the converted voltage value. Furthermore, the difference between the voltage values of two adjacent cells can be read. Therefore, for example, the difference between the values of the charges newly added from the hold units a and b in the 2i-1th and 2ith cells can be read. With this function, in the present embodiment, the voltage signal corresponding to the charge of 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 influence of disturbance light can be eliminated.
[0052]
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.
[0053]
FIG. 5 is a diagram for explaining the output signal of the signal readout unit of the ring CCD in the first embodiment of the present invention. In the example shown in FIG. 5, the voltage values are in order from the nth pixel to the first pixel. It has been read. Here, the output level in the vicinity of the i-th pixel is high because, 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, a temporal shift from the center axis position, which is a preset reference position, to a position where the output level is the highest (i-th pixel in the case of FIG. 5), that is, the value of A in FIG. 5 is obtained by calculation. As a result, a value serving as a base of the coordinate value of the X axis (or Y axis) can be obtained.
[0054]
<Control of ring CCD>
Next, control of the ring CCD described above will be described. In the present embodiment, the X-coordinate and Y-coordinate direction sensors 7 and 8 that are ring CCDs perform an operation of taking in coordinate data for one point of the light spot 3 as described above by the timing sequence by the control signal generation circuit 21. Repeat.
[0055]
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.
[0056]
Signals indicated with [] 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 CCD). Other signals are signals given to the sensor from the outside.
[0057]
When the signal “CCD_RESET” is given to these ring CCDs, the signal “CCD_SP” is obtained by dividing the predetermined timing clock “CCD-CLK” supplied from the control signal generating circuit 21 by 8 using this signal as a trigger. And the signal “IRCLK” is generated by dividing the signal “CCD_SP” by 150 (therefore, the signal “IRCLK” is a signal obtained by dividing the timing clock “CCD-CLK” by 1200). Here, the signal “CCD_SP” is the transfer clock of the circular transfer path 34 as described above. Further, as described above, the signal “IRCLK” is a reference signal for the operation of turning on the electronic shutter twice and transferring the charge from the photoelectric conversion unit 30 to the circulation transfer path 34.
[0058]
First, a signal “LOOP_CLR” is supplied to the line CCDs 7 and 8 from the outside in synchronization with the signal “IRCLK”. With this signal, the charge remaining in the circulation type transfer path 34 is cleared. Thereafter, in accordance with the signal “IRCLK”, the charge circulating around the cyclic transfer path 34 is additionally accumulated sequentially, and the waveform of the output signal read from the signal reading unit 29 is represented by 53 to 58 in V_OUT (X). Gradually grows.
[0059]
The output level of the read waveform V_OUT (X) is monitored by the control signal generating circuit 21. When this output level reaches a predetermined value (threshold value), the signal “CCD_READ” becomes Hi. That is, the ring CCDs 7 and 8 continue to accumulate charges while the signal “CCD_READ” is Lo, and when the signal becomes Hi, the accumulation is stopped and only the charge circulation operation is performed (at this time, the signal V_OUT (X)). The waveform of is invariant). ,
Thereafter, as indicated by 57 in FIG. 7, the signal “AD_READ” becomes Hi, and accordingly, the analog voltage value V_OUT (X) is converted into a digital signal by the AD conversion unit 20, and then sent to the CPU 23. Sent.
[0060]
Here, as described above, the signal “CCD_READ” is Lo until V_OUT (X) reaches a predetermined value. Therefore, when the signal level is large (when the level of the irradiated light is large), the time during which “CCD_READ” is Lo is short, and conversely, when the signal level is small (when the level of the irradiated light is small). ), The time during which “CCD_READ” is Lo becomes longer. Therefore, the waveform of the analog voltage captured by the AD converter 20 is a predetermined voltage waveform regardless of the signal level of the light actually received by the CCD sensor. A large range can be taken.
[0061]
<Synchronization method of flashing light emitting element and electronic shutter function>
Next, a method of synchronizing the flashing of the light emitting element and the electronic shutter function will be described in detail.
[0062]
In the present embodiment, the light emission period “LED_DRIVE” of the light emitting element 15 of the indicator 1 is 7.6 KHz that is obtained by dividing the signal “LED_CLK” generated by the LED_CLK generation circuit 12 by 128. Further, the frequency of the electronic shutter repetition frequency 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 for the signal “IRCLK”, and this signal is the signal “CCD_CLK” as described above. "Corresponds to a signal obtained by dividing 1200". That is, the flashing frequency on the light emitting side and the repetition cycle of the electronic shutter on the light receiving side are set in advance approximately the same.
[0063]
Here, as shown in FIG. 7, the timing sequence of the ring CCDs 7 and 8 is made to start with the signal “CCD_RESET”. However, the rising timing of the signal “IRCLK” generated by the CCD is not limited. The signal “CCD_RESET” is configured in advance so as to be immediately after the falling timing of the signal. Therefore, the phase of the signal “IRCLK” can be controlled by controlling the timing of the signal “CCD_RESET”. That is, the signal “CCD_RESET” is delayed by a predetermined time T1 (for example, 77.2 μs) with respect to 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. By setting the timing so that "" falls, the phases of "IRCLK" and "LED_IR" can be matched at least immediately after the signal "CCD_RESET". This is equivalent to synchronizing the blinking cycle of the indicator 1 and the phase of the electronic shutter operation of the ring CCDs 7 and 8.
[0064]
FIG. 11 is a flowchart showing the synchronization processing between the blinking cycle of the pointing tool and the electronic shutter operation of the ring CCD according to the first embodiment of the present invention, and shows processing executed by the CPU 23.
[0065]
As shown in the figure, immediately before the start of the timing sequence in step S3, the time is adjusted in step S2, so that the phases of the signals “IRCLK” and “LED_IR” are matched at that time, and then one point of spot 2 is obtained. During the detection period (that is, until the timing sequence ends), the signals “IRCLK” and “LED_IR” are free-runned, respectively. Further, when the timing sequence in step S3 ends, 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 phase, and then the next timing sequence is started.
[0066]
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, this frequency deviation will be described.
[0067]
In this embodiment, the maximum period for capturing the coordinates of one point of the light spot 3 by the ring CCDs 7 and 8 is 40 ms. This corresponds to the period of the signal “CCD_RESET” shown in FIG. 7 being a maximum of 40 ms, which means that the free run period is a maximum of 40 ms.
[0068]
In the present embodiment, it is assumed that a general crystal resonator is used for the LED_CLK generation circuit 12 of the pointing tool 1 and the CCD-CLK generation circuit 22 of the signal processing unit 24. The frequency accuracy of a general crystal resonator is better than 100 ppm. Here, for example, when the frequency accuracy of the crystal resonator is 100 ppm, the phase deviation that can occur during the free-run period is 40 ms × 100 ppm = 4 μs, and this value is the period of the signal “IRCLK” (131 .6 μs) to the lighting period (Hi period) is sufficiently smaller than 33 μs.
[0069]
Therefore, even during the free run period, the signals “IRCLK” and “LED_IR” can be substantially synchronized, and the synchronization operation between the pointing tool 1 and the light receiving side can be realized wirelessly.
[0070]
<Switch 11 of indicator 1>
The indicator 1 is provided with a switch (SW) 11 as shown in FIG. 2, and as an example, it can be used for causing the light receiving unit 27 to recognize pen up / down. Hereinafter, a method for causing the light receiving unit 27 to recognize the operation of the switch 11 will be described.
[0071]
In this embodiment, the lighting period when the light emitting element 15 blinks by the drive signal “LED_DRIVE” is configured to be wholly or partially modulated by a carrier having a frequency sufficiently higher than the blinking frequency. With such a configuration, only the modulated part is detected by the light receiving element 4, so that only the modulated part has meaning as time axis information.
[0072]
Therefore, in the present embodiment, when the switch 11 on the indicator 1 is pressed, the drive waveform generation circuit 13 modulates the signal “LED_IRCLK” every other time, as shown in FIG. Drive signal “LED_DRIVE” is output to the drive circuit 14, and when the switch 11 is not pressed, modulation is performed every period of the signal “LED_IRCLK” as shown in FIG. 9.
[0073]
When the light emitted from the light emitting element 15 with the light emission pattern configured as described above is received by the ring CCDs 7 and 8, the signal blinks in the same cycle (T2) regardless of whether the switch 11 is pressed or not. When the signal is 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). That is, coordinate detection by the ring CCDs 7 and 8 is performed in the same manner in any case, and 1 bit is output as the output signal of the light receiving element 14 without affecting the synchronous operation of the flashing of the light emitting element 15 and the electronic shutter function. Minute information can be transmitted to the light receiving unit 27, and the status of the operation switch 11 can be detected.
[0074]
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 an electronic shutter function is realized by controlling the ring CCD from the outside. The indicator 1 was synchronized with the flashing cycle of light emission. Thereby, the influence of malfunction etc. by disturbance light can be excluded.
[0075]
In the present embodiment, the control signal supplied to the ring CCDs 7 and 8 switches between a state in which the charge generated in the photoelectric conversion unit 30 circulates while being additionally accumulated and a state in which only the circulation is performed without performing additional accumulation. In this configuration, switching of the state is performed in accordance with the amount of light emitted from the indicator 1 and, for example, when receiving light with a low light receiving level, the charge corresponding to the received light is transferred to the ring CCD. In the case where light having a high light receiving level is received, charges corresponding to the received light are stored in the ring CCD a few times. As a result, accurate coordinate detection can be performed even when the amount of irradiation light varies, and the dynamic range of light that can be received can be widened.
[0076]
In this embodiment, 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 of the light-receiving unit 27, but the blinking cycle of the indicator 1 And the electronic shutter function of the ring CCDs 7 and 8 in the light receiving unit 27 can be synchronized. That is, in this embodiment, each time the coordinate data for one point is processed, the ring CCD 7 with reference to the head portion or the end portion of any one light emission pulse of the flashing signal detected by the light receiving element 4. And 8 can be synchronized, the blinking of the indicator 1 and the electronic shutter function of the light receiving unit 27 can be synchronized, the influence of disturbance light can be suppressed, and high accuracy and high resolution can be achieved. A two-dimensional coordinate value can be obtained.
[0077]
Further, in this embodiment, the light emission signal on the light emission side not only blinks at a predetermined cycle, but at the time of lighting, simple modulation is performed with a carrier having a frequency sufficiently higher than the blinking frequency, and the light receiving element 4 receives light. The transmitted signal passes through a band-pass filter having a resonance point at substantially the same frequency as that of the carrier, so that only the frequency component substantially the same as that of the carrier contained in the received light signal can be extracted. Thereby, also in the light receiving element 4, the influence by disturbance light can be excluded.
[0078]
[Second Embodiment]
Next, a second embodiment of the present invention will be described based on the device configuration in the first embodiment described above. In the following description, the description of the same part as that of the first embodiment is omitted, and the characteristic part in the present embodiment will be mainly described.
[0079]
FIG. 12 is a block diagram showing a system configuration of the coordinate input device according to the second embodiment of the present invention.
[0080]
In the present embodiment, a signal “IR” is transmitted from the waveform processing circuit 19 to the control signal generation circuit 21 as in the first embodiment, and a PLL (PHASE LOCK LOOP) is generated based on the signal “IR”. The signal “IR_P” generated at 72 is sent to the control signal generation circuit 21.
[0081]
The waveform processing circuit 19 passes the signal received by the synchronization light-receiving element 4 through a bandpass filter 62 (see FIG. 8) having a resonance circuit having the same frequency as the carrier frequency described in the first embodiment, thereby causing disturbance light. Therefore, ambient light can be sufficiently removed in a general use environment. However, in an extremely rare environment where much larger disturbance light than expected is incident, the influence may not be completely removed. In such a case, noise such as 80, 81, and 82 shown in FIG. 13 is mixed in “FILTER_OUT” that is the output of the bandpass filter 62, so that the waveform processing circuit 19 shows 83 and 84 in FIG. Is expected to be output as the signal “IR”, so that the control signal generation circuit 21 may erroneously recognize the head portion or the end portion of the signal “IR”. However, these whisker-like noises output from the bandpass filter have little energy as compared to the original output signal from the bandpass filter. Therefore, in the present embodiment, the adverse effect is avoided by generating the signal “IR_PLL” in the PLL 72 having a general configuration in accordance with the signal “IR” output from the waveform processing circuit 19.
[0082]
According to the coordinate input device of the second embodiment having such a device configuration, not only the same effect as the coordinate input device in the first embodiment can be obtained, but also a more accurate operation can be realized. .
[0083]
【The invention's effect】
As described above, according to the present invention, the coordinate input device detects the coordinate position of the light spot generated in the predetermined two-dimensional coordinate plane with high accuracy and high resolution by suppressing the influence of disturbance light. Is realized.
[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 is a schematic diagram showing a configuration of a ring CCD that can be employed in the first embodiment of the present invention.
4 is a diagram illustrating a portion from the i-th photoelectric conversion unit 30 illustrated in FIG. 3 to the 2i-1 and 2i-th portions of the cyclic transfer path 34. FIG.
FIG. 5 is a diagram illustrating an output signal of a signal reading unit of the ring CCD according to the first embodiment of the present invention.
FIG. 6 is a timing chart for explaining an electronic shutter function of a ring CCD.
FIG. 7 is a timing chart illustrating a timing sequence for controlling the operation of the ring CCD in the first embodiment of the present invention.
FIG. 8 is a block diagram showing an internal configuration of a waveform processing circuit according to the first embodiment of the present invention.
FIG. 9 is a timing chart illustrating drive waveforms of the light emitting element according to the first embodiment of the present invention.
FIG. 10 is a diagram for explaining a drive signal on the light emission side and an output signal of a waveform processing circuit in the first embodiment of the present invention.
FIG. 11 is a flowchart showing a synchronization process between the blinking cycle of the pointing tool and the electronic shutter operation of the ring CCD in the first embodiment of the present invention.
FIG. 12 is a block diagram showing a system configuration of a coordinate input device according to a second embodiment of the present invention.
FIG. 13 is a diagram for explaining a drive signal on the light emission side and an output signal of a waveform processing circuit in the second embodiment of the present invention.

Claims (7)

Detecting the indication position indicated by the emitted light in a predetermined blink period from the finger示具, a coordinate input device which outputs the detected coordinate information,
First light receiving sensor for detecting the emitted light,
A second light receiving sensor for detecting a change in the time series of the emitted light,
The second based on a change in time series of said detected light emitted by the light-receiving sensor for the flashing cycle of the emitted light, the first synchronization control for synchronizing the detection operation of the light receiving sensor Means,
Calculation means for calculating coordinates of the indicated position based on a signal output from the first light receiving sensor in a synchronized state by the synchronization control means;
A coordinate input device comprising: The coordinate input device according to claim 1, wherein the first light receiving sensor is two line sensors arranged in two directions not parallel to each other. The line sensor is a ring CCD including a photoelectric conversion element and a ring-shaped charge transfer path capable of accumulating while sequentially adding charges generated in the element,
The synchronization control means causes the ring CCD to perform photoelectric conversion on the photoelectric conversion element in synchronization with the blinking cycle of the emitted light, and transfers charges generated by the conversion to the charge transfer path. Circulate and accumulate while adding sequentially in synchronization with the blinking cycle,
3. The calculation unit according to claim 2, wherein the calculation unit sequentially reads out the electric charge accumulated in the charge transfer path as an electric signal, and calculates the coordinates of the indication position based on a difference between the read electric signals. Coordinate input device. 4. The synchronization control unit changes a period for accumulating while sequentially adding charges generated in the photoelectric conversion element in the charge transfer path according to a light amount of the emitted light. Coordinate input device. The synchronization control means, the coordinates of the indicated position each time the processing 1 point fraction, the second based on a change in the time series of the emitted light detected by the light receiving sensor, blinking of the emitted light 2. A start timing or an end timing of one lighting period in a cycle 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. The coordinate input device according to claim 4. The indicator includes modulation means for modulating the lighting period of the flashing light to be emitted by a carrier having a frequency sufficiently higher than the flashing frequency,
The synchronization control means passes an electric signal representing the emitted light detected by the second light receiving sensor through a band pass filter having a resonance point at substantially the same frequency as the carrier, 2. The coordinate input device according to claim 1, further comprising a waveform processing circuit for extracting only a frequency component substantially the same as the carrier contained in the electric signal. The indicator further includes an operation switch, and a modulation control means for controlling the presence or absence of modulation by the modulation means in accordance with the operation of the switch,
The synchronization control means, on the basis of the change in the time series of second electrical signals representative of light the emitted detected by the light receiving sensor, by determining the presence or absence of modulation by the modulating means, the switch The coordinate input device according to claim 1, further comprising detection means for detecting an operation state.

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