JP2005165832A - Optical coordinate input device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coordinate input device capable of easily detecting whether a pen is lifted up or put down. <P>SOLUTION: This optical coordinate input device is provided with a first coordinate detection mode for detecting the position of a pointer based on interruption of retroreflection light, which is emitted in substantially parallel to a coordinate input face, by the pointer and determining whether the pen is lifted up or put down by detection of light emission from the pen according to a sensor output signal. In calculation of the coordinate in the first coordinate detection mode, only the light emission from the pen is detected when light energy higher than predetermined retroreflection light is detected, for example, and a switch to a second coordinate detection mode for calculating the light emission position of the pen is carried out. Then, return to a first coordinate calculation mode is carried out when the light emission from the pen is not detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coordinate input device, and more specifically, coordinates used to control a connected computer or to write characters, figures, etc. by inputting coordinates by pointing to an input surface with an indicator or a finger. The present invention relates to a technology for improving the performance of an input device.

  Conventionally, various types of touch panels have been proposed or commercialized as this type of device, and are widely used because operations of a PC or the like can be easily performed on a screen without using a special instrument.

  There are various methods such as those using a resistive film and those using ultrasonic waves. As a method using light, a retroreflective sheet is provided outside the coordinate input surface to illuminate the light. In the configuration in which the light from the means to reflect is reflected by the retroreflective sheet and the light distribution is detected by the light receiving means, the angle of the area shielded by the finger or the like in the input area is detected, and the coordinates of the shielding position, that is, the input position Is known (see, for example, Patent Document 1). Also, in Japan, a retroreflective member is configured around the input region, and an apparatus for detecting the coordinates of the portion where the retroreflected light is shielded is disclosed.For example, the peak of the light shielding portion is obtained by waveform processing calculation such as differentiation. By detecting, the method of detecting the angle of the light-shielding part (see, for example, Patent Document 2), or comparing one end and the other end of the light-shielding part by comparison with a specific level pattern, and detecting the center of those coordinates A configuration (see, for example, Patent Document 3) is shown.

  The touch panel in various methods will be described in more detail. A device called a touch panel detects a touched position by touching an input surface with a finger or an indicator, and is based on the resistance film method described above. In this case, the position is detected by detecting a change in the electrical resistance value by touching the input surface. It is configured to detect the touch position by observing the phenomenon that the ultrasonic vibration propagating is attenuated. In other words, in the resistive film method or the ultrasonic method, the position detection is not performed unless the input surface is touched. Conversely, the fact that the position detection is performed means that the input surface is touched. Means state.

  However, in the coordinate detection method for detecting the light shielding position based on the light shielding described above, a light beam for detection (light width h2) at a position (a height h1 from the input surface) that is a predetermined distance away from the input surface. Since the shielding position is detected by shielding the luminous flux with a shielding object, the coordinate value is not necessarily detected even if the coordinate input surface is not touched (the height above the input surface). (See FIG. 20 for h1 and light width h2.) As a result, handwriting that is different from the coordinate input intended by the operator, such as “tailing”, is input, and the disadvantage that the operability is remarkably deteriorated is revealed.

  This “tailing” will be described in detail with reference to FIG. 21. In order for the operator to input the character “A” now, a finger or pointing tool equivalent is moved as shown in FIG. 21-1. Assuming that As shown in Fig. 21-2, the operator assumes the character "A", touches the input surface with the solid line in Fig. 21-1, and operates the broken line in Fig. 20-1. The moving operation is executed without touching. In other words, it is assumed that the operator recognizes that he / she touches the input surface and leaves a handwriting, but the operator actually does not touch the input surface immediately before / after touching the input surface. First, coordinate detection is performed, and the character information actually displayed is as shown in FIG. 21-3. That is, despite the input of the character “A”, an extra trajectory is displayed immediately before / after touching the input surface, and a display different from the trajectory intended by the operator can be obtained. This phenomenon is called “tailing”. Due to the occurrence of tailing, the information intended by the operator is not displayed, and problems such as “difficult to see”, “cannot write small letters”, “cannot draw detailed graphic information”, etc. Occurs.

  Further, when the double click operation is to be realized by the operation by the operator, the operator executes the double click operation by touching the input surface → up (1) → touch → up (2). At this time, for example, the coordinate input device can output coordinate values at predetermined intervals (for example, the coordinate detection sampling rate of 100 points / second has the ability to output coordinates every 5 msec). With the output timing and the coordinate value output at that time, that is, the coordinate value A is output at a certain time, and the coordinate value is not detected by sampling after a predetermined time (for example, at the coordinate detection sampling rate of 100 points / second, 5 msec time If the coordinate value is not detected even after elapses, it means that the coordinate input operation has been interrupted), and the next output coordinate value B is predetermined from the time when the coordinate value A was output. It can be determined that the double-click operation has been performed when the coordinate value A and the coordinate value B are substantially equal within the time and the coordinate sampling after a predetermined time is interrupted.

  In this operation, the operator only knows whether or not the input surface has been touched, and it is determined how far the input surface should be separated in the above-described state (1). When the coordinate input device continues to detect coordinates even though the operator recognizes that “the indicator has been released” because the operator cannot recognize that the indicator has been released from the input surface 6 in up (1). In a state where it is not sufficiently separated), the result is that the double-click operation intended by the operator cannot be detected. In order to solve this problem and to realize the double-click operation reliably, the operator must operate with the “full stroke” in the up (1) state, with the indicator sufficiently separated from the input surface. However, since the operator cannot immediately recognize how much the “sufficient stroke” is, he has to over-act. In other words, it cannot be said that the device is excellent in operability.

  Therefore, in the coordinate detection method for detecting the light shielding position based on the light shielding, the coordinate detection is performed while the input surface is touched, or the coordinate detection is performed in the vicinity of the input surface. A means for discriminating whether the operation is performed is an indispensable configuration for improving the operability. In view of the above points, as a method for detecting the height of the finger or the pointing tool from the input surface, a configuration is disclosed in which a plurality of thresholds for the amount of light shielded are provided to reduce the influence (for example, Patent Documents). 4, 5).

Also, by performing a coordinate input operation on the coordinate input surface, emitted light is emitted from the pen, and in order to obtain the position coordinates of the pen, the emitted light is received by a plurality of detection units arranged outside the coordinate input surface. Thus, there is also disclosed a system for converting into electrical signals and processing the electrical signals to calculate position coordinates (see, for example, Patent Reference 6).
US Patent No. USP4507557 Patent Publication No. 2000-105671 Patent Publication No. 2001-1472642 Patent Publication No. 2001-147776 Patent publication number 2001-84106 Patent publication number H11-3170

  In order to avoid / improve the above-mentioned problems, the height h1 from the force surface and the width h2 of the light flux are reduced as much as possible to bring them closer to the “state in which the position is detected by touching the coordinate input surface”. In practice, however, in an apparatus having a large input surface, there is a limit to reducing the height h1 from the input surface due to tolerances such as flatness of the input surface.

  Specifically, in general, a large display device, particularly a conference system in which a large number of participants hold a conference using the display device, the display size is about 60 inches to 100 inches diagonal or more. A large display device is required. Furthermore, since the surface of the display device is a coordinate input surface, it is required that the display surface does not bend even when pressed by a finger or the like. Therefore, the display surface is made of a material having rigidity, but considering that the display area is large and transparency is necessary, for example, if glass is used, the plate thickness is considerably large. Thick ones are required and must be heavy equipment.

  Furthermore, in a rear projector type display device used as a current large display device, the display surface is usually composed of a transparent resin plate having optical characteristics such as a Fresnel lens and a lenticular lens. The increase in the plate thickness not only increases the weight, but also deteriorates the light transmittance and the like, and lowers the function as a display device.

  Therefore, as a countermeasure usually taken, a method of increasing the rigidity by providing a curvature on the display surface is performed even if it is a little. If the central portion of the display surface is configured to be convex, h1 at the central portion of the display area can be set to “0” as much as possible. However, since the display surface is convex at the periphery of the display area, h1 corresponding to at least the bulge height is set in order to prevent the light beam from being blocked by the display surface. H1 cannot be set to “0” in the entire display area (= input area) (specifically, if the bulge of the display surface is 5 mm higher at the center than at the periphery, h1 at the periphery needs to be at least 5 mm) Would say). On the other hand, even when the central portion of the display surface is recessed, it is possible to set it to almost “0” at the peripheral portion of the display area, but this is not the case at the central portion of the display area.

Although described above from the viewpoint of rigidity, even if sufficient rigidity is obtained, it is difficult to set h1 to “0”. Since it is easier to image with specific figures, if you have a display device with a diagonal size of 70 inches and an aspect ratio of 3: 4, the display area is about 1060 mm x 1420 mm. The area is about 1.5 m ² . Considering the flatness of the display surface material, the flatness of the mounting surface, or the effects of thermal expansion, the flatness of the display surface should be maintained at almost “0” with this display surface incorporated in the device. It is impossible, and even if the tolerance is about ± 1 mm, there is great industrial difficulty. Therefore, it can be said that it is difficult to set the value of h1 to “0” from this viewpoint.

  Further, reducing the width h2 of the light beam has the effect of improving the above problem. In this case, however, the light emission intensity of the light source and the optical system for collecting the emitted light are expensive. Is generated separately and is not a practical solution to the problem.

  Furthermore, for example, when the operator touches the coordinate input surface using the pointing tool, the pen itself emits light, and the light is detected by a plurality of sensors to obtain the position coordinates of the pointing tool. Since the light emission means pen-down, the above-mentioned problems such as “tailing” do not occur. However, when performing coordinate input, a light-emitting pen is indispensable. For example, functions such as “proximity input” described in detail in the embodiments of the present invention cannot be realized, and operability is improved. It cannot be said that it is an excellent method.

  In order to solve the above-described problems, the present invention provides a coordinate input device capable of performing coordinate input using an indicator having a light-emitting means that is turned on according to the operating state of the indicator. A plurality of light receiving detection means provided at the corners, a retroreflective means for recursively reflecting incident light provided at the periphery of the coordinate input effective region, and a coordinate input surface toward the retroreflective means. A light quantity distribution obtained from the light receiving means by having a light projecting means for projecting the light flux in parallel and a light receiving means for receiving the light flux retroreflected by the retroreflecting means, and shielding the light flux by an indicator The light receiving means detects the light from the position calculating means for calculating the position coordinates of the light shielding part by the pointing tool and the light emitting means of the pointing tool that is turned on according to the operating state of the pointing tool. Gain from means A change in light intensity distribution, to have a detecting means for detecting the operating state of the pointing tool, which is constituted so as to detect the operating state of the position coordinates, and pointing device of the pointing device.

  Furthermore, a switch means that is turned on / off when the tip of the indicator touches the coordinate input surface is provided, and a light emitting means that is turned on / off according to the on / off of the switch means is provided in the indicator. Since the light receiving means is configured to be able to determine the position coordinates of the pointing tool and whether or not the pointing tool is in contact with the coordinate input surface, the “tailing” may be used when inputting characters or the like. In addition to preventing a drop in operability due to the operation, the "double click" operation by the operator can be reliably detected. Furthermore, since the light shielding position by the pointing tool and the operating state of the pointing tool can be detected by the same light receiving means, the configuration is simplified and can be manufactured at low cost.

  Further, the amount of light received by the light receiving means that receives light from the pointing tool that flashes in accordance with the operating state of the position pointing tool exceeds a predetermined value because the light intensity from the pointing tool is strong. In such a case, since the light projection by the light projecting unit is interrupted, only the light generated by the pointing tool is detected by the light receiving unit, and the position coordinates of the light emitting portion of the pointing tool are calculated. Even when such a phenomenon occurs, the position coordinates of the pointing tool can be detected with high accuracy.

  Further, even when the position coordinates are detected by the light from the pointing tool, when the projection of the light from the pointing tool is interrupted, the coordinate input surface is substantially directed toward the retroreflective means. The light projecting means for projecting the light beam in parallel starts its operation, and the pointing tool is changed by the change in the light amount distribution obtained from the light receiving means caused by blocking the light beam projected by the light projecting means with the pointing tool or the like. Since the position coordinates such as are calculated, the operation state of the pointing tool can be reliably detected even when the light intensity from the pointing tool is high.

  As described above, in the present invention, the pen up / down can be easily detected by the light emitting pen, so that the operability as the coordinate input device is remarkably improved and the proximity input is realized. Now, you can easily input fine characters and complex figures. Furthermore, since the light signal emitted from the light-emitting pen 8 is simultaneously detected using the sensor unit 1 for detecting the light shielding part without using a special element, the configuration of the coordinate input device is simplified. Also, an excellent advantage that the apparatus can be configured at low cost can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

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

  In the figure, reference numerals 1L and 1R denote sensor units 1 each having a light projecting means and a detecting means. In the case of this embodiment, as shown in the figure, they are set at predetermined positions parallel to the X axis and symmetrical to the Y axis. It is arranged at a distance. The sensor unit 1 is connected to the control / arithmetic unit 2, receives a control signal from the control / arithmetic unit 2, and transmits the detected signal to the control / arithmetic unit 2. Reference numeral 3 denotes a reflecting means having a retroreflective surface for reflecting incident light in the direction of arrival, and retroreflects the light projected from the left and right sensor units 1 in a range of approximately 90 ° toward the sensor unit 1.

  The reflected light is detected one-dimensionally by the detecting means of the sensor unit 1 constituted by a condensing optical system and a line CCD, and the light quantity distribution is sent to the control / arithmetic unit.

  The coordinate input effective area 4 described above can be used as an interactive input device by being configured by a display screen of a display device such as a PDP, a rear projector, or an LCD panel.

  With this configuration, when an input instruction with a finger or the like is given to the input area, the light projected from the light projecting means is blocked by the finger or other instruction means, and the detection means of the sensor unit 1 It becomes impossible to detect the light of only the part (reflected light by retroreflection), and as a result, it becomes possible to determine from which direction the light could not be detected. In other words, the arithmetic control means of the control / arithmetic unit 2 detects the light-shielding range of the input instructed from the light quantity change of the left and right sensor units 1, and derives the direction (angle) of the light-shielding position from the information on the light-shielding range. . Furthermore, the coordinate position on the input area is calculated from the derived direction (angle) and the distance information between the sensor units 1L and 1R, etc., and the PC connected to the display device is connected to a USB or the like. Output coordinate values via the interface.

  In this way, it is possible to draw a line on the screen with an indicator such as a finger or to control the PC by operating an icon on the display screen.

  Hereinafter, the configuration and operation of each part will be described in detail.

<Detailed description of sensor unit 1>
FIG. 3 shows a configuration example of the light projecting means in the sensor unit 1.

  Fig. 3-1 is a view of the light projecting means viewed from the front direction (perpendicular to the coordinate input surface 6). In the figure, 31 is an infrared LED that emits infrared light, and the emitted light is a light projecting lens. 32 emits light in a range of approximately 90 °. On the other hand, FIG. 3-2 is a side view of the same configuration seen from the side (horizontal direction with respect to the input surface). In this direction, the light from the infrared LED 31 is projected as a light beam restricted in the vertical direction. Mainly, the light is projected to the retroreflective means 3.

  FIG. 4 shows the detection means in the sensor unit 1. Like FIG. 3, FIG. 4-1 shows the front direction (perpendicular to the coordinate input surface 6), and FIG. It is the side view. The broken line portion in the front view 4-1 shows the arrangement of the light projecting means in the sensor unit 1 described above shown in the side view 4-2. In the case of the present embodiment, the light projecting means and the detection means are arranged so that the distance L is sufficiently smaller than the distance from the light projecting means to the retroreflective means 3, and the distance L is present. Even if it does, it becomes the structure which can detect sufficient retroreflection light with a detection means.

  In FIG. 4B, the detection means of the present invention includes a one-dimensional line CCD 41, lenses 42 and 43 as a condensing optical system, a diaphragm 44 for limiting the incident direction of incident light, and extraneous light such as visible light. The infrared filter 45 that prevents incidence, and the light projected by the light projecting means is reflected by the retroreflective member 3, passes through the infrared filter 45 and the diaphragm 44, and is collected by the condensing lenses 42 and 43. It is focused on the CCD detection surface.

  Similarly in FIG. 4A, the light of the light projecting means projected in the approximately 90 ° direction is reflected by the retroreflective member 3 and collected through the infrared filter 45 and the aperture 44. The light lenses 42 and 43 form an image on the pixel of the CCD 41 corresponding to the incident angle of the reflected light. Accordingly, since the output signal of the CCD 41 outputs a light amount distribution corresponding to the incident angle of the reflected light, the CCD 41 pixel number indicates angle information.

<Description of control / arithmetic unit>
Between the control / arithmetic unit 2 of FIG. 2, the sensor unit 1L, and the sensor unit 1R, a CCD control signal, a CCD clock signal, a CCD output signal, and an LED drive signal are exchanged.

  FIG. 5 is a block diagram of the control / arithmetic unit. The CCD control signal is output from an arithmetic control circuit 83 constituted by a one-chip microcomputer or the like, and performs CCD shutter timing, data output control, and the like. The CCD clock is sent from the clock generation circuit 87 to the sensor unit, and is also input to the arithmetic control circuit 83 in order to perform various controls in synchronization with the CCD.

  The LED driving signal is supplied from the arithmetic control circuit 83 to the LED driving circuits 84L and 84R to the infrared LED 31 in the sensor unit 1.

  Detection signals from the CCD 41 serving as detection means of the sensor unit 1 are input to the AD converters 81L and 81R in the control / arithmetic unit 2 and converted into digital values under the control of the arithmetic control circuit 83. The converted digital value is stored in the memory 82 as necessary, the angle is calculated by a method described later, and further the coordinate value is obtained, and the result is output to an external PC or the like via the serial interface 88 or the like.

<Explanation of light intensity distribution detection>
FIG. 6 is a timing chart of control signals.

Reference numerals 91, 92, and 93 denote control signals for CCD control, and the shutter release time of the CCD is determined by the interval of 91SH signals. Reference numerals 92 and 93 denote gate signals to the left and right sensors, respectively, which are signals for transferring the charge of the photoelectric conversion unit in the CCD to the reading unit.
Reference numerals 94 and 95 denote left and right LED drive signals. In order to light one LED (the LED in the sensor unit 1L) in the first cycle of SH, the 94 drive signal is an LED drive circuit (in this case, the LED drive circuit 84L). ) To be supplied to the LED. In the next cycle, the other LED (in this case, the LED in the sensor unit 1R) is driven. After the driving of both LEDs is completed, the CCD signal is read from the left and right sensors.

  For example, when there is no input by a finger or an indicator, that is, when there is no light-shielding portion, a light amount distribution as shown in FIG. 7A is obtained as an output from each sensor. Of course, such a distribution is not necessarily obtained in any system. The distance from the light projecting means to the retroreflective sheet (optical path length), the characteristics of the retroreflective sheet (for example, the retroreflective efficiency depending on the incident angle of the retroreflective member). Dependence), characteristics of the light projecting means including the LED, and changes with time (dirt of the reflecting surface, etc.) change this distribution.

  In FIG. 7A, if the A level is the level when the maximum light amount is detected and the B level is the lowest level, the obtained level will be in the vicinity of B in the absence of reflected light. The more you increase, the closer you are to level A. In this way, the data output from the CCD is sequentially AD converted and taken into the CPU as digital data.

  FIG. 7-2 shows an example of output when input is performed with a finger or the like, that is, when reflected light is blocked. Since the reflected light is blocked by the finger or the like at C, the amount of light is reduced only at that part.

  The detection is performed by detecting the change in the light amount distribution. Specifically, first, the initial state without input as shown in FIG. 7-1 (hereinafter, the data obtained in the initial state is referred to as the initial data. Is stored in the memory 82 in advance, and whether there is a change as shown in FIG. 7-2 by calculating the difference between the data obtained in each sample period and the initial data stored in advance. Determine if.

<Description of angle calculation>
In calculating the angle, it is first necessary to detect the light shielding range.

  As described above, since the light quantity distribution is not constant due to changes over time, it is desirable to store the above-mentioned initial data at the time of starting the system. In other words, if initial data is set at the time of shipment from a factory or the like and the data is not updated sequentially, for example, if dust adheres to the retroreflective surface at a predetermined position, the retroreflective efficiency at that portion decreases. Therefore, it causes a serious result that the coordinate input operation is performed at that position (direction viewed from the sensor), that is, erroneous detection is performed. Therefore, by storing the above-mentioned initial data at the time of starting up the system, even if the retroreflective surface is soiled with dust or the like over time and the retroreflective efficiency is reduced, the state can be reset as the initial state. As a result, it is possible to obtain an excellent advantage that there is no malfunction.

  Now, when the power is turned on, in the state where there is no input (there is no light-shielding part), the CCD output is first AD converted without illuminating from the light projecting means, and this is stored in the memory 82 as Bas_data [N]. . This is data including variations in the bias of the CCD 41 and the like, and is data near the level B in FIG. Here, N is a pixel number, and a pixel number corresponding to an effective input range is used. Next, the light quantity distribution in the state illuminated from the light projecting means is stored. The data is represented by a solid line in FIG. 7A, and is set as Ref_data [N], and the initial data storage is completed.

  Using these data, it is first determined whether an input has been made or whether there is a light shielding range.

  Data of a certain sample period is assumed to be Norm_data [N]. First, in order to specify the light shielding range, presence / absence is determined based on the absolute amount of change in data. This is to prevent erroneous determination due to noise or the like and to detect a certain amount of reliable change. The absolute amount of change is calculated for each pixel as follows and compared with a predetermined threshold value Vtha.

Norm_data_a [N] = Norm_data [N] − Ref_data [N] (1)
Therefore, Norm_data_a [N] corresponds to the absolute change amount in each pixel.

  Since this process only takes a difference and compares it, it does not use much processing time, and therefore it is possible to determine whether or not there is an input at high speed.

  When the number of pixels exceeding Vtha for the first time is detected exceeding a predetermined number, it is determined that there is an input.

  Next, in order to detect with higher accuracy, a change ratio is calculated to determine an input point. In FIG. 8, 121 is a retroreflective surface. Here, if the reflectance of the α region is reduced due to dirt or the like, the distribution of Ref_data [N] at this time has a smaller amount of reflected light in the region α as shown in FIG. In this state, if the pointing tool 5 such as a finger is inserted as shown in FIG. 8 and almost half of the retroreflective member is covered, the amount of reflected light is substantially halved. Therefore, the distribution Norm_data indicated by the thick line in FIG. [N] is observed. Applying equation (1) to this state, the result is as shown in Figure 10-1. Here, the vertical axis represents the differential voltage from the initial state.

  When this data is compared with the threshold value Vtha, there are cases where the original input range is deviated (broken line area in FIG. 10-1). Of course, by setting the threshold value Vtha to a smaller value, a certain degree of detection is possible, but the possibility of being affected by noise and the like increases, resulting in a problem that the coordinate calculation performance is degraded. Therefore, the amount of light blocked by the pointing tool 5 is the first half of both the α region and the β region (corresponding to the V1 level in the α region and equivalent to the level V2 in the β region), so the change ratio is calculated by the following equation.

Norm_data_r [N] = Norm_data_a [N] / (Bas_data [N]-Ref_data [N]) (2)
This calculation result is as shown in FIG. 10-2, and is represented by a fluctuation ratio. Therefore, even when the reflectance is different, it can be handled equally. A threshold Vthr is separately set for this data. Thus, from the pixel numbers of the rising and falling portions, for example, pixel information can be obtained with high accuracy using the center of both as the input pixel.

Incidentally, FIG. 10-2 is schematically drawn for explanation, and an actual detection signal waveform is shown in detail as shown in FIG. Now, it is assumed that the rising portion of the light-shielding region in comparison with the threshold value Vthr has exceeded the threshold value Vthr at the Nrth pixel, and has fallen below the threshold value Vthr at the Nfth pixel. At this time, as described above, the CCD pixel number Np of the CCD to be output is set as the median value of the pixel numbers of the rising and falling portions.
Np = Nr + (Nf-Nr) / 2 (3)
In this case, the CCD pixel interval becomes the resolution of the output pixel number. Therefore, in order to detect with higher resolution, calculation is performed using the output level information of the pixel.

In FIG. 11, the CCD output level of pixel number Nr is Lr, and the output level of pixel number Nr-1 is Lr-1. Similarly, the output level of the pixel number Nf is Lf, and the output level of the pixel number Nf-1 is Lf-1. If the pixel numbers to be detected at this time are Nrv and Nfv respectively,
Nrv = Nr-1 + (Vthr Lr-1) / (Lr Lr-1) (4)
Nfv = Nf-1 + (Vthr Lf-1) / (Lf Lf-1) (5)
Is calculated, a virtual pixel number corresponding to the output level, that is, a pixel number smaller than the CCD pixel number can be obtained, and the output virtual center pixel Npv is
Npv = Nrv + (Nfv-Nrv) / 2 (6)
Determined by

  As described above, by calculating the virtual pixel number from the pixel number and the output level of the pixel, detection with higher resolution becomes possible.

<Conversion from CCD pixel information to angle information>
Now, in order to calculate an actual coordinate value from the obtained center pixel number, it is necessary to convert the aforementioned pixel number into angle information.

FIG. 12 is a plot of the relationship between the obtained pixel number and the angle Θ. Approximate expression of this relationship Θ = f (N) (7)
The data is converted from this approximate expression. In the present invention, the lens unit of the detecting means in the sensor unit 1 described above is configured so that it can be approximated using a first order approximation formula. In some cases, it is possible to obtain angle information with higher accuracy. The lens group to be used is closely related to the manufacturing cost, and optical distortion generally generated by lowering the manufacturing cost of the lens group is corrected using a higher-order approximation formula. In such a case, since a certain amount of calculation capability (calculation speed) is required, both of them may be set appropriately in view of the coordinate calculation accuracy required for the target product.

On the other hand, when calculating the coordinate value from the angle information by the method described later, it is more trigonometric to calculate the tangent value at that angle than to calculate the angle itself from the obtained pixel number. This is convenient because it can be omitted. FIG. 13 is a plot of the tan θ value against the pixel number from this point of view. An approximate expression is obtained from this relationship, and the conversion from the pixel number to the tan θ value is performed using the approximate expression. For example, when a fifth order polynomial is used as an approximate expression, six coefficients are required, and this data is stored in a nonvolatile memory or the like at the time of shipment. If the coefficients of the fifth-order polynomial are now L5, L4, L3, L2, L1, L0, tanθ is
tanθ = (L5 * Npr + L4) * Npr + L3) * Npr + L2) * Npr + L1) * Npr + L0 (8)
It is obtained with. If the same calculation is performed for each sensor, each angle data can be determined.

<Description of coordinate calculation method>
FIG. 14 is a diagram showing a positional relationship with the screen coordinates. The coordinate input subordinate area 4 is arranged with the X axis in the horizontal direction, the Y axis in the vertical direction, and the center of the coordinate input effective area 4 at the origin position. 1R is mounted symmetrically about the Y axis, and the distance between the sensor units is Ds. As shown in the drawing, the light receiving surface of the CCD of the sensor unit 1 is arranged so that the normal direction forms an angle of 45 ° with the X axis, and the normal direction is defined as 0 °. The sign of the angle at this time is the clockwise direction in the case of the sensor unit 1L arranged on the left side, and the counterclockwise direction in the case of the sensor unit 1R arranged on the right side. Is defined as the “+” direction. Furthermore, P0 in the figure is the intersection point position in the normal direction of each sensor described above, and the distance from the origin in the Y-axis direction is defined as P0y. At this time, the angles P obtained by each sensor unit 1 are θL and θR, and the coordinates P (x, y) of the point P to be detected are

で得られる。

It is obtained with.

  As described above, the coordinate input device that detects the light shielding position by the finger or the pointing tool and detects the position coordinates of the finger or the pointing tool has been described. However, in this type of coordinate input device that obtains position coordinates by blocking light, as described in the problem section, even if the finger or the indicator is not in contact with the coordinate input surface 6, The light shielding position is calculated, and the following problem occurs.

  Specifically, the coordinate input device according to the present invention can be described with reference to a coordinate value of a specific region (a specific region is, for example, a region having a radius R centered on a certain coordinate value, or a certain coordinate value). It is assumed that when a specific place having a certain area is output in the meaning of a polygon or the like having a center of gravity, an operation assigned to the specific area is executed. That is, an icon indicating a switch is displayed on a portion corresponding to the specific area described above, and the operator touches (clicks) the icon to change any coordinate value in the area of the present invention. The coordinate input device outputs and is configured to execute the operation assigned to the switch.

  20-20 is a layout diagram seen from the front direction, for example, when the switch area is installed in the lower left corner of the coordinate input effective area. It is an example. That is, the configuration is intended so that the operator can perform control corresponding to on / off of the switch by instructing the region with the pointing tool 5 such as a finger. For example, a certain region can be instructed. In this way, a specific application can be started. FIG. 20-1 shows an outline of the AA cross section in FIG. 20-2. Reference numeral 6 denotes a member having a plane including the coordinate input effective area 4, and in the case of the present invention, also serves as a display surface of the display device as described above. The light beam illuminated by the light projecting means in the sensor unit 1 is emitted substantially parallel to the surface of the display device, is retroreflected by the retroreflective member 3, and is detected by the detection means in the sensor unit 1. As shown in FIG. 20-1, this luminous flux is set within the range of height h1 and width h2 from the display surface (corresponding to the installation range of the retroreflective member 3), but this height h1 is set to “0”. It is not easy to do for the following reasons.

  In general, in a large display device, particularly in a conference system in which a large number of participants hold a conference using the display device, the display size is about 60 to 100 inches diagonal or larger. Required. Furthermore, since the surface of the display device is the coordinate input surface 6, it is required that the display surface does not bend even when pressed by a finger or the like. Therefore, the display surface is made of a material having rigidity, but considering that the display area is large and transparency is necessary, for example, if glass is used, the plate thickness is considerably large. Thick ones are required and must be heavy equipment.

  Furthermore, in a rear projector type display device used as a current large display device, the display surface is usually composed of a transparent resin plate having optical characteristics such as a Fresnel lens and a lenticular lens. The increase in the plate thickness not only increases the weight, but also deteriorates the light transmittance and the like, and lowers the function as a display device.

  Therefore, as a countermeasure usually taken, a method of increasing the rigidity by providing a curvature on the display surface is performed even if it is a little. If the center of the display surface is configured to be convex, h1 at the center of the display area can be set to “0” as much as possible. However, the display surface is convex at the periphery of the display area. Therefore, since the luminous flux is blocked by the display surface, h1 must be set at least by the bulge height, and h1 cannot be set to “0” (specifically, the display surface) If the bulge is raised, for example, 5 mm higher at the center than at the periphery, h1 at the periphery will be at least 5 mm). Conversely, even if the center of the display surface is concave, it can be set to almost “0” at the periphery of the display area, but not at the center of the display area. That is, it is impossible to set h1 = 0 in the entire display area (coordinate input area).

Although described above from the viewpoint of rigidity, even if sufficient rigidity is obtained, it is difficult to set h1 to “0”. Since it is easier to image with specific figures, if you have a display device with a diagonal size of 70 inches and an aspect ratio of 3: 4, the display area is about 1060 mm x 1420 mm. The area is about 1.5 m ² . Considering the flatness of the material of the display surface, the flatness of the mounting surface, or the influence of thermal expansion, the flatness of the display surface is maintained at almost “0” when the display surface is incorporated in the device. It is impossible, and even if the value is about ± 1 mm, it is difficult to set the value of h1 to “0” because there is great industrial difficulty. I can say that.

  Now, in the situation as described above, it is assumed that a plurality of switch areas are set in the coordinate input effective area 4 as shown in FIG. 20-2. At this time, consider a case where the operator operates the switch 2 (SW2) to execute a desired application. The operator's hand / finger is not aware of the movement only in the direction perpendicular to the display screen (acting to touch the SW2 area in Fig. 21-2). Other than saying “in the SW2 area”, it is normal not to be aware of the movement trajectory of the hand / finger. For example, the operation is performed according to the trajectory indicated by the thick arrow in FIG.

  The operation that the coordinate input device determines in accordance with this moving operation will be described. First, the operator tries to execute the control assigned to the SW2 area, and touches the SW2 area to be substantially parallel to the display surface 6. It is assumed that the set light flux starts to be blocked and the finger / hand is moved to the position (1). When the light beam starts to be blocked, the coordinate input device of the present invention starts to output the coordinates of the light blocking position, and sets the down flag when the state (1) is reached. This down flag is a determination flag that is output together with the coordinate value in order to determine whether the operator touches the coordinate input surface 6, and indicates how much light is blocked (see FIGS. 8 to 10 in advance). As described with reference to FIG. 4, it is possible to determine how much of the luminous flux is shielded). The level at which the flag is set changes depending on the level at which the determination threshold is set. However, since at least the state (1) blocks almost all of the luminous flux, the down flag is set. At this point, since the operator has not yet touched the display surface 6, the switch is not intended to be operated, but the SW2 area is pressed at the position (2) (the position in contact with the display surface 6). It will be recognized that the switch has been operated. The operator achieves the purpose of performing the switch operation and moves the finger / hand to the position (3), but the coordinate input device sets the down flag even in the position (3). As it is (because almost all of the light beam is blocked), the coordinate values continue to be output. As the position moves to the position (4), the coordinate value is continuously output, but the amount of light to be blocked gradually decreases, the down flag is canceled at the position corresponding to the judgment threshold value, and the light beam is eventually emitted. The coordinate output will be stopped when there is no longer obstruction.

  The problem here is that the operator only recognizes that “the SW2 area has been pressed” in the state of (2), whereas the coordinate input device according to the present invention is shown in FIG. This is the point where the down flag set signal is output together with the coordinate value in the area labeled 20-1 shown in 20-1.

  That is, when the coordinate value output last with the down flag set is in the SW3 area due to a series of movements of the operator, the operator has surely pressed the SW2 area. The execution instruction assigned to the SW3 area will be executed. This not only gives the operator upsets, but depending on the contents of the execution command, there is a serious fear of causing an unrepairable state.

  As a countermeasure, for example, the space between the SW1 area and the SW2 area (gap) is made sufficiently large, or the coordinate value when the down flag is set is continuously monitored, for example, output during that period. Means such as setting the center of the coordinate value as a definite value can also be considered, but the former has a new problem such as a large gap between switches, poor operability, or a large number of switches cannot be arranged, Actions such as “I have pointed to the wrong area but moved the finger in the state of (2) and released the finger at the correct position to achieve the purpose” are often performed. However, this is not necessarily the correct position intended by the operator.

  Furthermore, as described in the section of the problem, the problem of “tailing” or the problem of not being able to detect an operation such as a double click realized by tapping the input surface twice within a predetermined time also occurs. ing.

  In order to solve the above-described problems, the embodiment of the present invention has a dedicated indication member (hereinafter referred to as a light-emitting pen 8) having switch means 61 for judging whether or not the tip 67 of the indication member 7 is in contact with the coordinate input surface 6. ). FIG. 15 is a diagram showing the internal configuration of the light-emitting pen 8. As shown in FIG. The light emitting pen 8 includes a battery 66, a converter 65 for boosting the battery voltage, a pen control circuit 64 that detects a switch signal and controls ON / OFF of light, a pen tip switch 61 provided in the pen tip 67, and light emission It consists of LED63. When the nib switch 61 is turned ON / OFF, the pen control circuit emits light output from the LED 63, and the emitted light output is reflected by the reflection block 62 and emits light in a direction perpendicular to the axial direction of the light-emitting pen 6. To do. The emitted light output is detected by the CCD 41 in the sensor unit 1.

  FIG. 16 is an explanatory diagram schematically illustrating output signals of the CCD 41 in a state where there is no radiated light from the light-emitting pen (when the light is turned off A) and in a state where light is emitted (when the light is lit). A-3 and Fig. B-3 are side views of the positional relationship between the coordinate input surface 6, the luminous flux, and the light emitting pen 8, Figs. A-2 and B-2 are front views, and Fig. A-0 is the output of the CCD 41. The waveform is shown. First, when the light is turned off, the light-emitting pen 8 is operated by the operator and the light projecting means in the sensor unit 1 shields the emitted light beam. The tip 67 has not yet been in contact, and therefore no light is emitted from the light-emitting pen 8 (when the light is extinguished). Therefore, as described in FIG. 7, the signal output from the CCD 41 has the waveform shown in FIG. A-0, and only the position detection based on the light shielding portion is performed. In addition, the C part enlarged view A-1 is an enlarged display of the signal portion (the C part shown in the broken line) shielded at this time.

  When the operator further moves the light-emitting pen 8 to bring the tip 67 of the light-emitting pen 8 into contact with the coordinate input surface 6, the pen tip switch 61 in the light-emitting pen 8 operates to move from the center of the light-emitting pen 8. Light emission is started (see FIGS. B-3 and B-2). Most of the emitted optical signal is collected on the light emitting LED 63 by the retroreflective member 3, but only a part of the emitted optical signal reaches the sensor unit 1 (thick arrow in FIG. B-2). line).

  At this time, the light-emitting pen 8 shields the light beam emitted by the light projecting means in the sensor unit 1 and a part of the optical signal emitted by the light-emitting pen 8 is detected by the CCD 41. Is as shown in Fig. B-1. Therefore, by comparing the signal waveform in the state of FIG. A-1 with the signal waveform in the state of FIG. B-1, the presence or absence of light emission from the light-emitting pen 8, that is, the light-emitting pen 8 touches the coordinate input surface 6. (Pen-up / pen-down determination) can be determined.

  FIG. 18 is a schematic diagram in which the horizontal axis indicates the CCD pixel number and the vertical axis indicates the change ratio Norm_data_r [N] of the CCD output signal described above, and the C portion is enlarged in which only the light shielding portion of the output signal of the CCD 41 is enlarged. FIG. 18-1 shows a signal in a pen-up state, and FIG. 18-2 shows a signal in a pen-down state. The discrimination between the two is set such that, for example, a value that is 10% lower than the maximum value of the signal detected for coordinate calculation is set to Vth_s (in the case of FIG. 18, the ratio of the change in the detected CCD signal The maximum value is = 1, and the threshold value Vth_s is set to a value 10% down from that value = 0.9). And in the case of FIG. 18-1, the signal exceeding Vth_s exists continuously, whereas in the case of FIG. 18-2, after the signal exceeding Vth_s is detected, a signal equal to or lower than Vth_s is obtained. After that, since a signal exceeding Vth_s is obtained again, the pen-up / pen-down can be detected by comparing the signal with the threshold value Vth_s.

  In the pen-up / pen-down detection method, in addition to the method based on the threshold value set based on the maximum value of the output signal of the CCD 41 necessary for the coordinate calculation described above, for example, the signal in FIG. On the other hand, since the signal in FIG. 18-2 is a signal waveform having a plurality of extreme values, for example, counting up the number of zero-cross points in the signal obtained by differentiating the signal waveform also allows pen-up / pen-down. It is possible to detect.

  FIG. 17 is a flowchart showing steps from data acquisition to coordinate calculation, and details a series of processing steps of the coordinate input device of the present invention.

  First, when the power is turned on in S101, various initializations such as port setting of the arithmetic control circuit and timer setting are performed in S102. S103 is a preparation for removing unnecessary charges that is performed only at startup. In a photoelectric conversion element such as a CCD, unnecessary charge may be accumulated when it is not operated, and if the data is used as it is as reference data, it becomes impossible to detect or causes erroneous detection. In order to avoid this, the unnecessary charge accumulated in the CCD is removed by reading the data from the CCD a predetermined number of times in S103 (S104) in the state where the light projecting means is not illuminated. Yes. S105 is a judgment sentence for repeating a predetermined number of times. S106 is data acquisition when the projection unit is not illuminated, which corresponds to the acquisition of Bas_data [N] described above as reference data, is stored in the memory in S107, and is used for subsequent calculations.

In S108, reference data Ref_data [N] corresponding to the initial light amount distribution when illuminated by the projection means is taken in, and similarly stored in the memory in S109.
The above steps are the initial setting operation when the power is turned on. Needless to say, this initial setting operation may be configured to operate according to the operator's intention using a reset switch or the like. Through this initial setting operation, the state shifts to a normal capturing operation state.

  If the signal is normally acquired in S110, the presence / absence of a light-shielding portion is determined based on the difference value from Ref_data in S111. If it is determined that there is no data, the process returns to S110 and capture is performed. If it is determined in S112 that there is a light-shielding area, the ratio is calculated by the processing of Expression (2) in S113. In S114, a rising portion and a falling portion are determined by a threshold with respect to the obtained ratio, and a pixel number is calculated by the equations (4), (5), and (6). For example, Tanθ is calculated from the obtained pixel number from an approximate polynomial (S115), and x and y coordinates are calculated from the Tanθ values of the left and right sensor units using equations (9) and (10) (S116).

  Next, in S117, it is determined whether the pointing tool such as a finger is touching the coordinate input surface 6. As described above, determining whether or not there is light emitted from the light-emitting pen 8 can be easily determined by comparing the signal waveform of the light shielding part. A down flag indicating that the tip member 67 presses the input surface and the pen tip switch 61 is operating is set (S118). If not, the down flag is reset (S119).

  In S120, since the coordinate value and the down state are determined, the data is transmitted to the host PC. This may be sent by serial communication such as USB, RS232, etc., or by any interface. On the sent PC side, the driver interprets the data and moves the cursor, changes the mouse button state, etc. by referring to the coordinate values, flags, etc., so that the PC screen can be operated. When the process of S120 is completed, the process returns to the operation of S110, and thereafter, this process is repeated until the power is turned off or a reset state is set according to the operator's intention. If the repetition period at this time is set to about 10 [msec], the coordinate input device can perform coordinate sampling at 100 times / second.

  Now, as in the embodiment of the present invention, by providing the pen tip switch 61 for accurately determining the positional relationship of the tip of the pointing tool with the coordinate input surface 6, the “tailing” described above is provided. It is possible to avoid the failure such as the above or the deterioration of operability. When such a dedicated writing instrument is used, a new advantage can be obtained by configuring as follows. As described with reference to FIG. 21, when coordinate input is performed using a shield such as a finger, it is preferable to reduce the value of h1 as much as possible due to restrictions on the setting of the down flag. However, when a dedicated writing instrument is used, the down flag can be easily set by another means, so this restriction is eliminated. Accordingly, as shown in FIG. 20-2, it is possible to intentionally set the value of h1 so that coordinate input can be performed even at a position away from the coordinate input surface 6. As a convenience, since the position of the pointing tool can be detected even at a position away from the coordinate input surface 6, for example, by moving the displayed cursor to the coordinate detection value, the position of the pointing tool is displayed on the display screen. Thus, it is possible to confirm the desired position on the display screen. This function that allows coordinate input even at a distant position will be referred to as “proximity input” hereinafter. The value of h1 is intentionally set in order to realize the proximity input, and the various types described above are generated by setting the value of h1. The problem is solved by detecting the state of the pen tip SW61.

  Now, let us examine the light intensity projected by the light projecting means and the light intensity emitted from the pointing tool according to the operating state of the pointing tool. As described above, the light quantity distribution (see FIG. 7A) obtained by the sensor unit 1 is the distance from the light projecting means to the retroreflective sheet (optical path length), the characteristics of the retroreflective sheet (for example, the retroreflective member This distribution changes depending on the retroreflective efficiency depending on the incident angle), the characteristics of the light projecting means including the LED, and changes with time (such as dirt on the reflecting surface). For example, in detail with reference to FIG. 2, the light path of light passing through the coordinate input effective area projected from the sensor unit 1L (the light projected from the light projecting means is reflected by the retroreflecting means and received by the light receiving means. Is the smallest in the α direction and the largest in the β direction. Further, when the incident angle to the retroreflective means is considered, the retroreflective efficiency is good at the point α, but the efficiency decreases at the point β. Therefore, it can be easily understood that the light quantity distribution detected by the CCD 41 is not uniform only by considering this. At this time, for example, when the light-emitting pen 8 is positioned at a point γ in the coordinate input effective area in the β direction and light is emitted from the light-emitting pen by the switch means, at least light is received as shown in FIGS. 16A-1 and 16B-1. It must emit enough light to detect changes in the output signal of the means. On the other hand, if the distance between the light source and the sensor is shortened, the light intensity detected by the sensor increases exponentially. For example, the light emitting pen 8 is positioned at the position δ, and the equivalent light described above is used. When radiated, the intensity of light incident on the sensor unit 1L becomes too high, and the signal output from the sensor unit 1L may be greatly distorted as shown in FIG. 19B-2. That is, the output signal of the sensor unit 1 is distorted when the light-emitting pen 8 emits light due to the size of the coordinate input effective area 4, the positional relationship of the sensor unit or the retroreflective member 3, or the performance of the optical components. The case cannot be avoided by design.

  Therefore, as shown in FIG. 19B-2, a coordinate detection method when a distorted signal waveform is obtained will be described with reference to FIG.

  19A, 19A, and A-2 in FIG. 19 are a reprint of FIG. 16. In FIG. A-2, the light emitting pen 8 is operated by the operator, and the light projecting means in the sensor unit 1 is This shows the state where the emitted light beam is shielded, but the coordinate input surface 6 and the tip portion 67 of the light-emitting pen 8 are not yet in contact with each other, and therefore no light is emitted from the light-emitting pen 8 (when the light is turned off). . Accordingly, the signal output from the CCD 41 has the waveform shown in FIG. A-0, and position detection based on the light shielding part is performed. In addition, the C part enlarged view A-1 is an enlarged display of the signal portion (the C part shown in the broken line) shielded at this time.

  When the operator further moves the light-emitting pen 8 to bring the tip 67 of the light-emitting pen 8 into contact with the coordinate input surface 6, the pen tip switch 61 in the light-emitting pen 8 operates to move from the center of the light-emitting pen 8. Light emission is started (FIG. B-3), and only a part of the emitted light signal reaches the sensor unit 1.

  At this time, the light-emitting pen 8 shields the light beam emitted by the light projecting means in the sensor unit 1 and a part of the optical signal emitted by the light-emitting pen 8 is detected by the CCD 41. Is as shown in Fig. B-1 or Fig. B-2. That is, in the state of FIG. B-1, light incident from the light-emitting pen 8 is small, and the signal based on FIG. A-0 described above is used to derive the light shielding portion and detect the position coordinates. By comparing the B-1 signals, the pen-down / pen-up state can be detected (first coordinate calculation means and method). On the other hand, the state shown in FIG. B-2 shows a state in which the light incident from the light-emitting pen 8 is large and, for example, the CCD output exceeds the dynamic range of the CCD 41 and is saturated. Therefore, the output signal of the CCD 41, particularly the influence of the pixel whose output has been saturated, is greatly affected, and the output signal is greatly distorted, making it difficult to calculate an accurate light shielding part. Therefore, the present invention is configured to determine that a signal as shown in FIG. B-2 has been detected and calculate coordinates by the second coordinate calculation means (method).

  This second coordinate calculation means is a method of first stopping the light projection from the light projection means, detecting only the light signal from the light emitting pen 8 with the CCD 41, and calculating the light emission position. The signal shown will be obtained. As a specific method for calculating the pixel number, the processing method of the output signal described in the first calculation method may be applied. Therefore, the details thereof will not be described here, but the light emission direction of the light-emitting pen 8 is easily described. Can be obtained, and the light emitting pen position coordinates can be calculated using the pixel number and, for example, Equations 7-10.

  In such a state (a state in which the signal is distorted and the coordinate calculation is performed by the second calculation method), the tip 67 of the light-emitting pen 8 contacts the coordinate input surface 6 and the switch means 61 is moved. Since it occurs when it is operated (see FIG. C-1), that is, when it is in a pen-down state, a pen-down signal is always output when transitioning to the second coordinate calculation means.

  If the light emission from the light emitting pen 8 is lost, the second coordinate calculation means cannot detect the position coordinate of the light emitting pen 8, but in this case, a light emission signal cannot be obtained from the CCD 41 (as shown in FIG. C-0). Therefore, when this is detected, the coordinate calculation means is returned to the first coordinate calculation means, and the position coordinates of the light-emitting pen 8 are calculated in the state shown in FIG. A-2. Will do. Note that. The state switched to the first calculating means means that the light emission from the light-emitting pen is interrupted, that is, the pen-up state is entered.

  The first calculation unit, the second calculation unit, and the switching determination unit thereof have been described above. When switching determination is performed, for example, when the signal in FIG. B-2 is obtained, the information is used for determination. Will be missing (coordinate output will not be performed). However, it has been confirmed that there is no problem in the deterioration of operability due to this by the following experimental verification.

  Using a coordinate input device that can detect coordinates with an indicator that can detect pen-up / pen-down by touching the coordinate input surface, such as the light-emitting pen 8, the pen-down information is reflected with a delay of N sampling after detecting the pen-down. If the coordinate input device has a coordinate sampling rate of 100 points / second (coordinate output every 10 msec), for example, N = 5, the coordinates after 50 msec (= 10 msec × 5) even if a pen-down signal is detected As a result of experiments, the operator can input characters without any sense of incongruity even when N = 5 at a coordinate sampling rate of 100 points / second. Therefore, if the coordinate sampling rate is sufficiently high, even if pen down information or coordinate values are missing, operability is not affected.

  Further, the method of determining that the signal is abnormal based on the signal of FIG. B-2 may be determined based on the signal level at which the signal of the CCD 41 saturates, or the signal level in FIG. When the signal level is exceeded, it is determined as abnormal (meaning that light larger than the light by the light projecting means is detected), or the level set based on the signal level in FIG. There is a method of setting a signal obtained by increasing the signal of 7-1 by about 10% as a threshold).

  In addition, when shifting to the second coordinate calculation means based on the signal in FIG. B-2 (the light intensity from the light-emitting pen 8 is too high), the possibility of saturation of the signal shown in FIG. C-0 cannot be denied. . In that case, it can be said that it is preferable to determine that an optical signal of a predetermined level or more is incident based on a threshold value or the like, for example, to shorten the shutter time of the CCD 41 and to make the output signal of the CCD 41 smaller. .

  FIG. 1 is a flowchart illustrating the coordinate value processing method described above, and will be described in order (details regarding the first coordinate calculation method have already been described with reference to FIG. 17). Only a brief explanation).

  First, when power is turned on in S201, initialization is performed in S202 (corresponding to S102 to s109 in FIG. 17). This initial setting operation is configured to operate according to the operator's intention using a reset switch or the like. Needless to say, it goes through the initial setting operation to shift to a normal capturing operation state.

  In S203, light is projected by the light projecting means, and the optical signal is acquired and output by the CCD 41. If no signal is obtained, the process returns to S203 and the operation is repeated. When a signal is output, it is determined in S205 whether the signal is an abnormal signal, that is, a signal corresponding to FIG. 19B-2. If the signal is normal, the light is projected by a light projecting unit from S206 to S208. The position where the received light is blocked is calculated, it is determined whether the signal corresponds to FIG. 19A-1 or FIG. 19B-1, and the operation state of the light-emitting pen 8 is determined (s209 to s211). The coordinate value obtained in S212 and the down flag are transmitted to an external device or the like, and the process returns to step s203. The above process corresponds to the first coordinate calculation means.

  If it is determined in S205 that the signal is abnormal (corresponding to FIG. 19B-2), the process proceeds to the second calculation means. First, the second calculation means takes in the signal of the CCD 41 in a state where the light projection means is turned off at s213, and shifts to s203 when there is no signal at s214 (transition to the first calculation means). To do. If a signal is obtained, it is determined whether the signal is saturated, for example, at s215. If the signal is saturated, for example, the shutter time of the CCD 41 is set shorter and the signal is acquired again at s213. . If it is determined in s215 that the signal is normal, the light emission position coordinates of the light emitting pen 8 are calculated in S217 to S219, the down flag is set (s220), and the information is output to an external device or the like (s221). ) And return to s213.

  In such a configuration, it is assumed that the character “a” shown in FIG. 21-1 is input (in the figure, the solid line is in the pen-down state and the broken line is in the pen-up state). It is assumed that the condition for generating an abnormal signal corresponding to FIG. 19B-2 is satisfied only when the position of the pointing tool is in the vicinity of (1) and in the vicinity of (3).

  First, when the operator points down the light-emitting pen 8 by pointing to the position of (1), the coordinate input device acquires a signal in s203 and detects an abnormality in s205 (because it corresponds to the signal in FIG. 19B-2). Therefore, light emitted from the light emitting pen is detected in s213, and the light emission position is calculated based on the second calculation means. Until the light-emitting pen moves to the position (2), the operator intends to pen down and the light-emitting pen always emits light. Therefore, the position coordinates are calculated by the second calculation means. . Since the operator continues to move the light-emitting pen to the position (3) in the pen-up state, the light emission from the light-emitting pen is interrupted, and the process shifts to the first calculation means according to the determination in s214. At this time, the position of the light emitting pen is calculated by shielding the light of the light projecting means by the first calculation means, and a signal equivalent to FIG. 19A-1 is obtained, so that a pen-up signal is output. (For the operator, as the light-emitting pen moves, for example, the operator recognizes the state where the cursor is attached). Since the pen-down is performed again at position (3) and writing is attempted, light emission from the light-emitting pen is performed, and a signal equivalent to FIG. 19 and B-2 is obtained at the position (3). Similarly, the position is calculated by the second coordinate calculating means, and the handwriting up to position (4) is left. Since the pen is in the pen-up state at the position (4), the transition is made to the first coordinate calculation means, and the light-emitting pen starts to emit light again at the position (5) by the pen-down operation by the operator. At position (5), since a normal signal as shown in FIG. B-1 is acquired, it is determined whether the signal is equivalent to the first calculation means and the signal corresponding to FIG. 19A-1 or FIG. 19B-1. The pen-down flag is determined, and the trajectory up to position (6) is input. That is, the trajectory (1) → (2), the trajectory (3) → (4) is calculated based on the second arithmetic means, and the trajectory (5) → (6) is calculated based on the first arithmetic means. Become.

  Now, once it transits to the second computing means, it returns to the first computing means only when the light emission of the light-emitting pen is interrupted. Therefore, in the previous example, even if it is an abnormal signal when it is at the position (1), it is highly likely that it is a normal signal when it is at the position (2). Of course, when the position (2) is at the position γ in FIG. 2, the output signal of the sensor unit 1L in FIG. 19C-0 is predicted to be considerably small. However, since the light emission amount of the light-emitting pen 8 is set so that the difference between the signals in FIGS. 19A-1 and 19B-1 can be determined even at this position, the signal corresponding to FIG. 19C-0 has sufficient sensitivity. It is clear that

  In addition, the flowchart in FIG. 1 describes one sensor. As shown in FIG. 2, for example, in the case of two sensor units, a calculation unit is set for each sensor unit. Needless to say.

Flowchart of the coordinate value processing method of the present invention Schematic configuration diagram of coordinate input device Explanatory drawing explaining the light projection means in the sensor unit 1 Explanatory drawing explaining the detection means in the sensor unit 1 Block diagram of control / arithmetic unit 2 Light emission timing chart Example of light intensity distribution (CCD output) Illustration of an example of change over time Explanatory diagram of light intensity change Explanatory diagram of light intensity change amount and light intensity change rate Illustration of shading range detection Illustration of relationship between pixel number N and angle Θ Illustration of relationship between pixel number N and tanΘ Illustration of coordinate calculation Schematic configuration diagram of light-emitting pen 8 Explanatory drawing explaining the difference of CCD output by the presence or absence of pen light emission Flow chart for coordinate calculation Explanatory drawing explaining determination of pen down / pen up Explanatory drawing explaining the determination method for calculating means setting Explanatory drawing explaining the tail that occurs when entering characters Explanatory drawing explaining the problem in click action

Explanation of symbols

1L, 1R Sensor unit 2 Control unit 3 Retroreflective member 4 Coordinate input effective area 5 Shading member 6 Display surface (coordinate input surface)
8 Light-emitting pen

Claims (6)

  A plurality of light receiving detection means provided at the corners of the coordinate input effective area, a retroreflective means for recursively reflecting incident light provided at the periphery of the coordinate input effective area, and toward the retroreflective means A light projecting means for projecting a light beam substantially parallel to the coordinate input surface; a light receiving means for receiving the light beam retroreflected by the retroreflecting means; and a light beam projected by the light projecting means by the instruction means. From a first position calculating means for calculating the position coordinates of the light-shielding portion by the pointing means, and a pointing tool provided with a light emitting means that flashes according to the operating state of the position pointing tool according to the change in the light amount distribution obtained from the light receiving means. A coordinate input device comprising second position calculating means for calculating the position coordinates of the light emitting part by the pointing tool based on a change in the light amount distribution of the light receiving means for receiving the light.   In the coordinate input device according to the first aspect, according to the light reception level of the light receiving means, the first position calculating means or the second position calculating means determines whether to calculate the position coordinates of the instruction means. Coordinate input device characterized by things.   In the coordinate input device according to the first and second items, when the position coordinate is detected by the first position calculating unit, the maximum value of the light amount distribution detected by the light receiving unit exceeds a predetermined value. In addition, the coordinate input device is switched to the second position calculating means.   In the coordinate input device according to the first and second items, when the second position calculation unit detects the position coordinates, and the light receiving unit cannot detect the light emission, A coordinate input device that switches to one position calculating means.   The first coordinate calculation unit in the coordinate input device according to the first item is based on a change in a light amount distribution obtained from the light receiving unit generated by blocking a light beam projected by the light projecting unit with an indicator. From the position calculation means for calculating the position coordinates of the light shielding part by the pointing tool, and from the change in the light quantity distribution obtained by the light receiving means depending on the presence or absence of light from the light emitting means of the pointing tool that flashes according to the operating state of the pointing tool A coordinate input device characterized by comprising a detecting means for detecting an operation state of the tool. The coordinate input device according to any one of the first, second, fourth, and fifth aspects, wherein the light emitting means that blinks in accordance with the operating state of the pointing tool provided in the pointing tool is a tip portion of the pointing tool. Coordinate input device characterized by blinking based on the output result of the switch means that is turned on / off by touching the coordinate input surface.

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