JP2017016531A - Coordinate input device, control method thereof, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an input of a pointer accurately.SOLUTION: Deriving means derives a fist component, which is a difference between a first light-receiving signal generated on the basis of the light received by light-receiving means, while projection means does not project light, when no pointer exists on a coordinate input surface, and a second light-receiving signal generated on the basis of the light received by the light-receiving means, while the projection means projects light, when no pointer exists on the coordinate input surface. The deriving means derives a second component, which is a difference between a third light-receiving signal generated on the basis of the light received by the light-receiving means when the projection means does not project light and a fourth light-receiving signal generated on the basis of the light received by the light-receiving means when the projection means projects light after the first and second light-receiving signals are generated. Detection mean detects an input on the coordinate input surface, on the basis of a difference between the first component and the second component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coordinate input device that optically detects a coordinate position input to a coordinate input surface by an indicator such as a finger, a control method thereof, and a program.

  Various types of coordinate input devices (touch panels and digitizers) have been proposed or commercialized as coordinate input devices that detect the coordinate position input to the coordinate input surface by an indicator such as a finger. For example, a touch panel that can easily operate a terminal such as a PC (personal computer) by touching the screen with a finger without using a special instrument is widely used.

  There are various coordinate input methods such as a resistive film method, an electromagnetic induction method, an electrostatic induction method, and an optical method. Of these, as an optical method, a retroreflective material is arranged outside the coordinate input surface, the light from the light projecting portion is retroreflected by the retroreflective material (incident light is reflected in the incident direction), and the retroreflected light An optical shading method is known in which an input position is calculated by detecting a light amount distribution by a light receiving unit. For example, Patent Document 1 discloses a coordinate input device using an optical shading method. In addition, the optical method eliminates the need for retroreflecting material outside the coordinate input surface, and detects the light quantity distribution of the light reflected from the indicator such as a finger to calculate the input position. An optical system is also known. Patent Document 2 discloses a coordinate detection apparatus using a direct reflection method.

  By integrating this type of coordinate input device with the display device, the display state can be controlled by touching the display screen of the display device, or the locus of the input position can be written by hand as if it were a pencil and paper. Can be displayed.

  As display devices, various types of flat panel displays such as liquid crystal display devices and front projectors are known. In the case of a flat panel display, such an operating environment can be realized if a coordinate input device is placed on the flat panel display, and a mobile device such as a smartphone can be said to be a representative example. In addition, along with the increase in the size of flat panel displays, it has been introduced in fields such as digital signage and electronic blackboards in combination with large touch panels.

JP 2014-48960 A JP 2013-80516 A

  By the way, when detecting reflected light in the direct reflected light system, there are several problems as follows, for example. For example, when the ambient light from a lighting fixture or the like enters the light receiving unit, the input position and the light receiving level may not be detected correctly. In addition, even when the light projected from the light projecting part is reflected by various objects outside the display screen, such as a desk, chair, wall, etc. It may not be detected correctly. Furthermore, it is conceivable that the position of the ambient light, the object, etc. outside the display screen fluctuates with time. In order to correctly detect the touch input, the incident light to the light receiving unit is reflected light from an indicator such as a finger touching the display screen, or reflected light from an ambient light or an object outside the screen. It is necessary to distinguish whether there is.

  In order to reduce the adverse effects due to these problems, several methods have been disclosed so far. For example, Patent Document 2 discloses a technique for discriminating ambient light by controlling the spectrum of light projection and light reception.

  In addition, it is considered that the problem caused by the ambient light from the lighting fixture or the like as described above entering the light receiving section also occurs in the optical light shielding method.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a coordinate input device, a control method thereof, and a program capable of detecting input by an indicator with higher accuracy.

  The coordinate input device of the present invention includes a light projecting unit that projects light in a direction along the coordinate input surface, at least two light receiving units that can receive light from the direction along the coordinate input surface, and the coordinate input surface. A first light-receiving signal generated based on light received by the light-receiving means when no light is projected by the light-projecting means when there is no indicator on the coordinate input surface; A first component that is a difference from a second received light signal generated based on the light received by the light receiving means when light is projected by the light projecting means when no indicator is present. A third light receiving signal generated based on the light received by the light receiving means when no light is projected by the light projecting means, and the first and second light receiving signals are generated. By the light projecting means later Deriving means for deriving a second component that is a difference from the fourth light receiving signal generated based on the light received by the light receiving means when light projection is performed, the first component, Based on the difference from the second component, detection means for detecting an input to the coordinate input surface by an indicator, and detection when the detection means detects an input to the coordinate input surface by the indicator. Calculating means for calculating the position of the input on the coordinate input surface.

  According to the present invention, it is possible to detect an input by an indicator more accurately.

It is a schematic block diagram of the coordinate input device of each embodiment. It is a block diagram of the calculation control part of each embodiment. It is a flowchart which shows the process which CPU of 1st Embodiment performs. It is a figure which shows the example of light quantity distribution used for operation | movement description of the apparatus of 1st Embodiment. It is a flowchart which shows the process which CPU of 2nd Embodiment performs. It is a figure which shows the example of light quantity distribution used for operation | movement description of the apparatus of 2nd Embodiment.

  Hereinafter, a coordinate input device according to an embodiment of the present invention will be described with reference to the drawings. The configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

<Configuration Example of First Embodiment>
In FIG. 1, as a first embodiment, an outline of a direct reflection light type coordinate input apparatus that detects light reflected by an indicator and calculates coordinates of an input position by the indicator. The configuration is shown. In the case of the coordinate input device according to the present embodiment, an image is projected and displayed on a display surface such as a planar whiteboard 4 using a front projector (not shown). Hereinafter, an area in which an image from a front projector or the like is projected and displayed on the display surface of the whiteboard 4 is referred to as a display area 5. The front projector projects and displays an image based on an image signal sent from, for example, a personal computer (hereinafter referred to as a PC 10) on the display area 5 on the whiteboard 4. In the present embodiment, an example is shown in which an image is displayed on the display surface of the whiteboard 4, but the display surface is not limited to the whiteboard, and may be a wall surface or the like.

  The sensor bar 1 includes a sensor unit 2a, a sensor unit 2b, an arithmetic control unit 3 and the like. In the following description, the sensor unit 2a and the sensor unit 2b are collectively referred to as the sensor unit 2 without being distinguished from each other. The sensor bar 1 is installed outside the display area 5 by a user, for example. The sensor bar 1 has, for example, a built-in magnet, and can be attached to a whiteboard 4 or the like configured with, for example, a ferromagnetic plate, by the magnetic force of the magnet.

  The arithmetic control unit 3 built in the sensor bar 1 controls the sensor unit 2 and performs arithmetic processing on an output signal from the sensor unit 2. Although details will be described later, the arithmetic control unit 3 processes the output signal of the sensor unit 2 when an instruction is input by an indicator such as a finger to the display area 5 that is a coordinate input surface. Calculate the input coordinates of the object. Then, the calculation control unit 3 outputs information on the input coordinates obtained by the calculation process to an external device such as the PC 10.

  Each of the sensor units 2a and 2b has a light projecting unit and a light receiving unit. The light projecting unit includes an infrared LED that projects light in a direction along the display area 5 (a direction substantially parallel to the display area 5), which is an example of a coordinate input surface, and a light projecting lens. . The light receiving unit includes a line CCD capable of receiving incident light and a light receiving lens. The light receiving surface of the line CCD is directed in the light projecting direction of the infrared LED. Since the internal structures of the light projecting unit and the light receiving unit are disclosed in detail in, for example, Patent Document 1, their description is omitted here. In addition to the structure disclosed in Patent Document 1, various structures can be used for the light projecting section and the light receiving section.

  1 is a configuration (retroreflective material 101, 102) provided in an optical shielding type coordinate input device described in a second embodiment to be described later. The direct reflected light system of the first embodiment is not necessarily required.

  FIG. 2 is a diagram illustrating an internal configuration example of the arithmetic control unit 3. A control signal for the line CCD of the sensor unit 2 is output from the CPU 61. The CPU 61 performs shutter timing of the line CCD of the sensor unit 2, data output control, and the like according to the control signal. A clock for the line CCD is transmitted from the clock generation circuit (CLK) 62 to each sensor unit 2 and is also input to the CPU 61 for performing various controls in synchronization with the line CCD. Further, the CPU 61 generates an LED drive signal for driving the infrared LED of the sensor unit 2, and performs switching control between a state in which infrared light is projected from the infrared LED and a state in which light is not projected. It is also possible. Various processors such as a microprocessor and a DSP may be used instead of the CPU, or they may be combined.

  The light reception signals of the respective line CCDs included in the sensor unit 2 a and the sensor unit 2 b are input to the A / D converter 63. The A / D converter 63 converts the light reception signal of the line CCD into a digital value under the control of the CPU 61. The digital data converted by the A / D converter 63 is stored in the memory 64 and used later for processing such as signal processing and angle calculation described later by the CPU 61. Then, the CPU 61 calculates input coordinates from the calculated angle information, and outputs the calculated coordinate data to an information processing apparatus such as the external PC 10 in FIG. 1 via an interface 65 (for example, a USB interface).

  The sensor bar 1 may include a user interface 66. The user interface 66 includes, for example, various switches used for switching a calibration mode, which will be described later, and a speaker for performing user notification using, for example, a beep sound. Note that the user interface 66 does not necessarily have to be provided when all the operation control including the mode switching of the sensor bar 1 and the user notification is performed by the PC 10.

<Reference reflection component derivation processing>
In FIG. 3A, the coordinate input device is turned on, and the CPU 61 starts execution of the control program of the present embodiment read into the memory 64 and detects the reference reflection component (for detecting the input by the indicator) ( It is a flowchart of a process until the memory | storage of (1st component) is completed. In the reference reflection component derivation process shown in FIG. 3A, the line CCD of the sensor units 2a and 2b removes the ambient light component from the received light signal that received the incident light, and the received light component after removing the ambient light component. , A process of storing as a reference reflection component. Hereinafter, the content of the reference reflection component derivation process will be described with reference to the flowchart of FIG.

  The arithmetic control unit 3 described above functions as a derivation unit, a detection unit, and a calculation unit when the CPU 61 executes a program read into a memory. These means may be realized by a single hardware or a plurality of hardware. In addition to the CPU, these means may be realized by using a microprocessor, a DSP, or an ASIC (application specific integrated circuit).

  Further, it is assumed that the reference reflection component derivation process is executed when there is no indicator on the coordinate input surface. As a method for determining that there is no indicator on the coordinate input surface, there are the following methods. For example, when there is no indicator on the coordinate input surface, the user may input an operation input for executing the reference reflection component derivation process. Alternatively, it may be determined that there is no indicator on the coordinate input surface when the signal received and generated by each line CCD has not changed for a certain period of time.

  In the flowchart of FIG. 3A, the arithmetic control unit 3 first initializes peripheral circuits such as input / output port setting, timer setting, resetting of charge accumulated in the line CCD, etc. as processing in step S102. I do. After step S102, the arithmetic control unit 3 advances the process to step S103.

  In step S103, the arithmetic control unit 3 turns off the infrared LEDs of the sensor units 2a and 2b and receives light by the line CCDs in the sensor units 2a and 2b in a state where no light is projected. Make it. As described above, in the reference reflection component derivation process, the signal generated by receiving the incident light in each line CCD in a state where the light is not projected by the infrared LEDs of the sensor units 2a and 2b is the first in the present embodiment. 1 is a light reception signal. The light reception signal of the line CCD in a state where the infrared LED is turned off is considered to be a signal indicating a light amount distribution of only ambient light (background light) not including an infrared light component by the infrared LED. In the following description, background light that does not include an infrared light component by an infrared LED is referred to as “non-projected background light”. The light reception signals when the non-projection background light is received by the line CCDs of the sensor units 2a and 2b are respectively digitized by the A / D converter 63 under the control of the arithmetic control unit 3, and the non-projection background is obtained. It is stored in the memory 64 as optical data.

  FIG. 4A is a diagram illustrating an example of a graph of the light amount distribution of the non-projection background light data. The horizontal axis in FIG. 4A indicates the pixel number of the line CCD, and the vertical axis indicates the amount of light. Note that the horizontal and vertical axes in FIGS. 4B to 4O described later are the same as those in FIG. In the case of the non-projection background light data illustrated in FIG. 4A, there is a region 401 where the amount of light is large near the center of the horizontal axis. In the region 401 where the amount of light is large, for example, infrared light included in ambient light from an incandescent lamp installed around the whiteboard 4 is incident on the line CCD as background light and received. It is thought that it is caused by.

  After step S103, the arithmetic control unit 3 advances the process to step S104. In step S104, the arithmetic control unit 3 turns on the infrared LEDs of the sensor units 2a and 2b and causes the line CCDs in the sensor units 2a and 2b to receive light in a state where light is being projected. . In this way, in the reference reflection component deriving process, incident light is received by each line CCD in a state where light is projected by both infrared LEDs of the sensor units 2a and 2b, and generated based on the received light. This signal is the second received light signal in this embodiment. The light reception signal of the line CCD in a state where the infrared LED is turned on is a signal obtained by adding an infrared light component in which the infrared light projected from the infrared LED is reflected by some object or the like to the ambient light. it is conceivable that. In other words, the light reception signal of the line CCD in this case is considered to be a signal indicating the light amount distribution in a state where the infrared light component resulting from the light projection of the infrared LED is added to the non-light-projected background light described above. It is done. In the following description, background light including ambient light and an infrared light component caused by an infrared LED is referred to as “projection background light”. The received light signals when the projected background light is received by the line CCDs of the sensor units 2a and 2b are respectively digitized by the A / D converter 63 under the control of the arithmetic control unit 3, and the projected background light is obtained. It is stored in the memory 64 as data.

  FIG. 4B is a diagram illustrating an example of a graph of the light amount distribution of the projection background light data. The light amount distribution of the projected background light data illustrated in FIG. 4B includes a region 401 where the light amount is large near the center of the horizontal axis and a region 402 where the light amount is large near the right end of the horizontal axis. is there. In the region 401 where the amount of light is large near the center of the horizontal axis, infrared rays from an incandescent lamp around the whiteboard 4 enter the line CCD as background light, as described with reference to FIG. The light quantity component generated in On the other hand, when FIG. 4B is compared with FIG. 4A described above, the light quantity distribution in FIG. 4B has a region 402 where the light quantity is large near the right end of the horizontal axis. This region 402 is generated, for example, when light projected from the infrared LED of the sensor unit 2 is reflected by some object existing around the outside of the whiteboard 4 and enters the line CCD. it is conceivable that. Note that some objects existing around the outside of the whiteboard 4 are various objects that reflect infrared rays, such as pens and other stationery, desks, chairs, room walls, floors, ceilings, and the like. it is conceivable that. Since these objects exist around the outside of the whiteboard 4, they are referred to as “outer objects” in the following description. In the example of FIG. 4B, for simplicity of explanation, only one light amount component of the reflected light from the outer object is present, but actually it exists around the outside of the whiteboard 4. There is a possibility that a light amount component of reflected light from various objects is detected over a wide range.

  After step S104, the arithmetic control unit 3 advances the process to step S105. In step S <b> 105, the arithmetic control unit 3 stores the projected background light data of FIG. 4B stored in the memory 64 and the non-projected background light data of FIG. 4A stored in the memory 64. Find the difference between More specifically, the arithmetic control unit 3 obtains a difference between the projected background light data by the line CCD of the sensor unit 2a and the non-projected background light data, and similarly, the projected background light data by the line CCD of the sensor unit 2b. And the difference between the non-projected background light data. In the present embodiment, an example of subtracting the non-projection background light data from the projection background light data is given as the difference calculation between the projection background light data and the non-projection background light data.

  FIG. 4C is a graph showing the light amount distribution when the non-projection background light data in FIG. 4A is subtracted from the projection background light data in FIG. 4B. In the light quantity distribution illustrated in FIG. 4C, there is a region 402 where the light quantity is large near the right end of the horizontal axis. In the example of FIG. 4C, the region 402 where the amount of light is large is obtained by changing the light from the infrared LED reflected by the outer object to the line as described with reference to FIG. This is the light quantity component detected by the CCD.

  The light amount component derived by the difference calculation between the projected background light data and the non-projected background light data is the reference reflection component in the present embodiment. Then, the arithmetic control unit 3 causes the memory 64 to store reference reflection component data indicating the reference reflection component immediately after the power is turned on. After calculating the reference reflection component data and storing it in the memory 64 as described above, the arithmetic control unit 3 ends the reference reflection component derivation process shown in the flowchart of FIG.

<Input detection processing (when the indicator is in a position that does not overlap with the background light)>
In FIG. 3B, after the above-described reference reflection component derivation process is completed, an input to the display area 5 is performed by an indicator such as a finger, and an operation control unit is detected when detecting an input by the indicator. 3 shows a flowchart of processing realized by executing the control program. Hereinafter, the flow of processing in the case where an input by an indicator such as a finger is performed at a position where it does not overlap with background light or reflected light from an outside object or the like as seen from each line CCD of each sensor unit 2 is shown in FIG. This will be described with reference to the flowchart of B).

  In the flowchart of FIG. 3B, the arithmetic control unit 3 first receives light by each line CCD in the state where the infrared LEDs of each sensor unit 2 are turned off and no light is projected as the process of step S108. Let it be done. Thus, in the input detection process, incident light is received by each line CCD in a state where light is not projected by both infrared LEDs of the sensor units 2a and 2b, and a signal generated based on the received light. Is the third light reception signal in the present embodiment. In the following description, the light reception signal of each line CCD at this time is referred to as “non-light projection data”. In this case, each infrared LED is turned off, and since it is considered that there is no reflected light in which the infrared light projected from the infrared LED is reflected by the indicator, the light amount distribution of the non-projected data is It is considered that the light amount distribution shown in FIG. The arithmetic control unit 3 stores the non-light projection data in the memory 64. After step S108, the arithmetic control unit 3 advances the process to step S109.

  In step S109, the arithmetic control unit 3 causes each line CCD to receive light in a state where the infrared LED of each sensor unit 2 is turned on and light is being projected. Thus, in the input detection process, incident light is received by each line CCD in a state where light is projected by both infrared LEDs of the sensor units 2a and 2b, and a signal generated based on the received light. Is the fourth light receiving signal in the present embodiment. In the following description, the light reception signal of each line CCD at this time is referred to as “light projection data”.

  FIG. 4D is a diagram illustrating an example of the light amount distribution of the light projection data. In the case of the light quantity distribution shown in FIG. 4D, compared with the example of FIG. 4B described above, the light quantity does not overlap with the background light or the reflected light from the outer object, for example, near the left end of the horizontal axis. The newly formed area 403 appears. In the present embodiment, it is assumed that a region 403 in which the light amount is large near the left end of the horizontal axis in the example of FIG. 4D is a light amount component of reflected light from an indicator in the display region 5. Then, the arithmetic control unit 3 stores the light projection data in the memory 64. After step S109, the arithmetic control unit 3 advances the process to step S110.

  In step S110, the arithmetic control unit 3 obtains the difference between the light projection data in FIG. 4D and the non-light projection data (FIG. 4A) stored in the memory 64, respectively. More specifically, the arithmetic control unit 3 obtains a difference between the light projection data and the non-light projection data by the line CCD of the sensor unit 2a, and similarly, the light projection data and the non-light projection data of the line CCD of the sensor unit 2b. Find the difference. In the present embodiment, as an example of the difference calculation between the light projection data and the non-light projection data, an example is given in which the non-light projection data is subtracted from the light projection data.

  FIG. 4E is a graph showing the light amount distribution after subtracting the non-projection data (FIG. 4A) from the projection data of FIG. 4D. In the light amount distribution illustrated in FIG. 4E, there are a region 402 where the light amount increases near the right end of the horizontal axis and a region 403 where the light amount increases near the left end. In the example of FIG. 4E, a region 403 with a large amount of light near the left end of the horizontal axis is a light amount component of reflected light from the indicator in the display region 5 described with reference to FIG. . On the other hand, a region 402 having a large amount of light near the right end of the horizontal axis in FIG. 4E is a light amount component of light reflected by the outer object described with reference to FIG. As described above, the data after the difference calculation between the projection data and the non-projection data is reflected light from various objects inside and outside the display area 5 (including the indicator when the indicator is present). It is data that contains the components. In the following description, the reflected light component obtained by the difference calculation between the light projection data and the non-light projection data is referred to as “total reflection component (second component)”. The arithmetic control unit 3 stores the total reflection component data in the memory 64.

  As described above, in the input detection process, the processes of step S108 to step S110 are performed only for the component of the reflected light by the projection of the infrared LED from the light reception signal received by the line CCD of the sensor units 2a and 2b. It is a process for extraction. After step S110, the arithmetic control unit 3 advances the process to step S111.

  In step S111, the calculation control unit 3 obtains a difference between the total reflection component data shown in FIG. 4 (E) and the reference reflection component data shown in FIG. 4 (C). More specifically, the arithmetic control unit 3 obtains a difference between the total reflection component data by the line CCD of the sensor unit 2a and the reference reflection component data, and similarly, the total reflection component data by the line CCD of the sensor unit 2b and the reference reflection component data. Find the data difference. In the present embodiment, an example is given in which the reference reflection component data is subtracted from the total reflection component data as the difference calculation between the total reflection component data and the reference reflection component data.

  FIG. 4F is a graph showing the light amount distribution after subtracting the reference reflection component data from the total reflection component data. In the light quantity distribution illustrated in FIG. 4F, there is a region 403 where the light quantity is large near the left end of the horizontal axis. In the example of FIG. 4F, this area 403 is the light quantity component of the reflected light from the indicator in the display area 5 described with reference to FIGS. 4D and 4E. Thus, the data obtained by calculating the difference between the total reflection component data and the reference reflection component data is data consisting only of the reflected light component by the indicator existing in the display area 5. Hereinafter, a component obtained by calculating a difference between the total reflection component data and the reference reflection component data, that is, a component of only reflected light from the indicator is referred to as an “input component”. The arithmetic control unit 3 stores the input component data in the memory 64. After step S111, the arithmetic control unit 3 advances the process to step S112.

  In step S112, the arithmetic control unit 3 detects whether there is an effective input component in the input component data that can be determined to be input by the indicator. More specifically, the arithmetic control unit 3 detects whether there is a valid input component for the input component data by the line CCD of the sensor unit 2a, and similarly, the input valid for the input component data by the line CCD of the sensor unit 2b. Detect if there is a component. For example, the arithmetic control unit 3 obtains a peak of the light amount in the input component, and performs a process such as determining that the input component is an effective input component if the peak value is larger than a predetermined first threshold value TH1. Note that the first threshold TH1 at this time is determined in advance based on the light emission intensity of the infrared LED of the sensor unit 2, the light receiving sensitivity of the line CCD, and the like. In the example of FIG. 4F described above, the peak value of the region 403 where the light amount is large near the left end of the horizontal axis is larger than the predetermined first threshold value TH1, and the peak is at one location. The operation control unit 3 determines that there is an effective input component from one indicator. The arithmetic control unit 3 obtains each pixel number corresponding to the peak position among the pixel numbers of the line CCDs of the sensor units 2a and 2b, and stores the data of these pixel numbers in the memory 64. . Thereafter, coordinate values on the coordinate input surface are calculated for this peak (peak pixel number).

  As described above, the processes in steps S111 and S112 are performed by comparing the input component data obtained by calculating the difference between the total reflection component data and the reference reflection component data with the first threshold value TH1, so that only effective input components are obtained. The detection process in this embodiment is detected.

<Input detection processing (when there is no indication in the display area)>
In the above description, an example is given in which an indicator is present in the display area 5 and an input is made by the indicator. However, if there is no indicator in the display area 5, FIG. Each data in steps S108 to S112 is as follows.

  When there is no indicator in the display area 5, the light quantity distribution of the non-projection data when the line CCD receives light with the infrared LED turned off in step S108 is the above-described FIG. Will be the same. Next, in step S109, the light quantity distribution of the light projection data when light is received by the line CCD with the infrared LED being projected is the same as that in FIG.

  Therefore, the total reflection component data obtained by subtracting the non-projection data in FIG. 4A from the projection data in FIG. 4B in step S110 is the same as the reference reflection component data in FIG. 4C. become. Therefore, the light amount distribution of the input component data obtained by subtracting the reference reflection component data in FIG. 4C from the total reflection component data (data similar to FIG. 4C) in step S111 is as shown in FIG. As in (G), it is substantially zero (0) over the entire area. In the case of the example of FIG. 4G, since there is no peak portion exceeding the first threshold TH1 in the input component, in the detection process of whether there is a valid input in step S112, the arithmetic control unit 3 is effective. It will be judged that there is no input.

<Input detection processing (when the pointing object is in a position overlapping the background light)>
In FIG. 4D described above, an example in which the indicator is present at a position that does not overlap with the background light when viewed from the line CCD side is given. However, when the indicator is present at a position that overlaps with the background light when viewed from the line CCD side. Each data of steps S108 to S112 in FIG. 3B is as follows.

  When there is an indicator at a position overlapping the background light when viewed from the line CCD side, the light quantity distribution of the non-projection data when the line CCD receives light with the infrared LED turned off in step S108 is as follows. As shown in FIG. In this case, there is an indicator at a position overlapping with the background light, and a part of the background light is blocked by the indicator, so that the light quantity distribution of the non-projection data is as shown in FIG. The distribution is such that a part of the amount of light in the background light region 401 of 4 (A) is reduced by being blocked by the indicator.

  Next, in step S109, the light quantity distribution of the light projection data when light is received by the line CCD with the infrared LED being projected is as shown in FIG. In this case, there is an indicator at a position overlapping with the background light, and the light projected from the infrared LED is reflected by the indicator, so in the line CCD, the background light and the reflected light of the indicator are Light will be received. Therefore, as shown in FIG. 4I, the light quantity distribution of the projection data seems to have a region 405 in which the reflected light of the indicator further overlaps the background light region 401 of FIG. Distribution.

  Therefore, in step S110, the light quantity distribution of the total reflection component data obtained by subtracting the non-projection data of FIG. 4H from the projection data of FIG. 4I is as shown in FIG. become. In FIG. 4J, the light quantity distribution of the total reflection component data includes an area 406 where the light quantity is increased by the reflected light of the indicator, and an area corresponding to the reflected light of the outer object described with reference to FIG. 402 is present in the distribution. Thereby, in step S111, the light quantity distribution of the input component data obtained by subtracting the reference reflection component data of FIG. 4C from the total reflection component data of FIG. 4J is as shown in FIG. become. As shown in FIG. 4K, the light quantity distribution of the input component data is a distribution in which only the light quantity peak area 406 caused by the reflected light of the indicator remains.

  In step S112, the arithmetic control unit 3 detects whether there is a valid input based on the input component data of the light quantity distribution as shown in FIG. In the case of the example of FIG. 4K, the peak of the region 406 where the amount of light is increased by the reflected light of the indicator is larger than the first threshold value TH1, and the peak is at one place. , It is determined that there is a valid input from one indicator. Then, the arithmetic control unit 3 obtains each pixel number corresponding to the peak position among the pixel numbers of the line CCDs of the sensor units 2a and 2b, and stores the data of these pixel numbers in the memory 64.

  As described above, even when the pointing object is present at a position overlapping the background light as viewed from the line CCD side, the calculation control unit 3 performs the processing in steps S108 to S111 in FIG. It is possible to reliably detect a valid input by the indicator.

<Input detection processing (when the pointing object is in a position overlapping the outside object)>
In FIG. 4 (I) described above, an example is shown in which an indicator is present at a position overlapping the background light when viewed from the line CCD side. However, when an indicator is present at a position overlapping the outer object when viewed from the line CCD side, Each data in steps S108 to S112 in FIG. 3B is as follows.

  When there is an indicator at a position overlapping the outer object as seen from the line CCD side, the light quantity distribution of the non-projection data when the line CCD receives light with the infrared LED turned off in step S108 is as described above. This is substantially the same as FIG.

  Next, in step S109, the light amount distribution of the light projection data when light is received by the line CCD with the infrared LED being projected is as shown in FIG. In this case, since there is an indicator at a position overlapping the outer object as seen from the line CCD side, the light projected from the infrared LED is reflected by both the indicator and the outer object. For this reason, the line CCD receives light in which the reflected light from the indicator and the reflected light from the outer object overlap. In the example of FIG. 4 (L), the amount of light increased by the reflected light from both the indicator and the outer object overlapping the region 401 near the right end of the horizontal axis together with the region 401 where the amount of light is increased by the background light. Ingredients appear. In the case of FIG. 4L, the region 407 near the right end of the horizontal axis is a light amount component in which the reflected light from both the indicator and the outer object overlaps, and thus the region 402 in FIG. 4B described above. Compared with the light amount component of the reflected light by the outer object in FIG.

  Therefore, in step S110, the light quantity distribution of the total reflection component data obtained by subtracting the non-light projection data of FIG. 4A from the light projection data of FIG. 4L is as shown in FIG. Become. In FIG. 4M, the light quantity distribution of the total reflection component data includes a region 407 where the reflected light from the indicator and the reflected light from the outer object described in FIG. 4C overlap. Distribution. Thereby, in step S111, the light quantity distribution of the input component data obtained by subtracting the reference reflection component data in FIG. 4C from the total reflection component data in FIG. 4M is as shown in FIG. become. As shown in FIG. 4N, the light quantity distribution of the input component data is a distribution in which only the light quantity peak region 408 due to the reflected light of the indicator remains.

  In step S112, the arithmetic control unit 3 detects whether there is a valid input based on the input component data of the light quantity distribution as shown in FIG. In the case of the example of FIG. 4N, the peak value of the region 408 corresponding to the reflected light of the indicator is larger than the first threshold value TH1, and the peak is at one place. , It is determined that there is a valid input from one indicator. The arithmetic control unit 3 obtains each pixel number corresponding to the position of the effective input peak among the pixel numbers of the line CCDs of the sensor units 2a and 2b, and stores the data of these pixel numbers in the memory 64. Remember me.

  As described above, even when there is an indicator at a position overlapping the outer object as viewed from the line CCD side, the calculation control unit 3 performs the processing of steps S108 to S111 in FIG. It is possible to reliably detect a valid input by the indicator.

<Input detection processing (valid input level detection and touchdown determination)>
After step S112, the arithmetic control unit 3 advances the process to step S113. Here, when a valid input is detected in the above-described step S112, as described above, the memory 64 stores a pixel number corresponding to the peak position of the valid input. Further, the memory 64 also stores the projection data as described above. In step S113, the calculation control unit 3 detects the light amount level corresponding to the pixel number of the effective input peak position as the input level in the light projection data stored in the memory 64. Here, a pixel number corresponding to a valid input peak position is represented as a pixel number GP.

  Here, in the present embodiment, the arithmetic control unit 3 detects the input data from the projection data because the above-described input component data may not necessarily represent a correct input level. For example, as shown in FIG. 4 (L) and FIG. 4 (M) described above, the indicator overlaps the outer object when viewed from the line CCD side, and the amount of light increases due to both reflected light from the indicator and the outer object. When the area 407 exists, the input component data is as shown in FIG. The input component data in FIG. 4N is calculated by subtracting the reference reflection component data in FIG. 4C from the total reflection component data in FIG. 4M. The level has decreased by the amount of light.

  For this reason, in the present embodiment, the input component data is used when detecting a valid input in the above-described step S112. On the other hand, when the correct input level is obtained, the light projection of FIG. It is necessary to use data. Therefore, in step S113, the arithmetic control unit 3 detects the light amount level corresponding to the pixel number GP at the peak position of the effective input as the input level in the light projection data of FIG. If the input level detected in step S113 (the light level corresponding to the pixel number GP of the effective input peak position) is greater than the predetermined second threshold TH2, the arithmetic control unit 3 touches the display area 5. It is determined that the touched-down state is a touched state or a substantially touched state. The second threshold TH2 in this case is determined in advance based on the light emission intensity of the infrared LED, the light receiving sensitivity of the line CCD, and the like, and is set to a value higher than the first threshold TH1 described above.

  In step S113, the arithmetic control unit 3 uses the total reflection component data shown in FIG. 4M stored in the memory 64, and the light amount level corresponding to the pixel number GP of the effective input peak position. May be detected as the input level. This is because the light amount level in the total reflection component data area 407 in FIG. 4M is not reduced by the subtraction of the reference reflection component data as in the input component data in FIG. This is because it is considered that the light amount level of the reflected light by the indicator is shown. However, when the input level is detected from the total reflection component data, the second threshold value used for determining the touchdown state is smaller than the second threshold value TH2 described above, for example, FIG. The second threshold value TH2g as shown in FIG. The second threshold TH2g is used because the above-mentioned projection data is the light level of the projection background light, whereas the total reflection component data is obtained by subtracting the non-projection data from the projection data. This is because the light amount level is lower than the light projection data. Therefore, when the input level is detected from the total reflection component data, in step S113, the calculation control unit 3 performs touchdown if the input level detected from the total reflection component data is greater than the predetermined second threshold TH2g. Judged to be in a state.

  In addition, although the example of FIG.4 (L)-FIG.4 (N) was used as description of step S113 here, in the case of above-mentioned FIG.4 (D) -FIG.4 (F), FIG.4 (H)-. In the case of FIG. 4K as well, the input level is detected and the touchdown state is determined in the same manner as described above.

<Input detection processing (responding to changes in the reference reflection component due to movement of the outer object, etc.)>
After step S113, the arithmetic control unit 3 advances the process to step S114. In step S <b> 114, the arithmetic control unit 3 performs a process for dealing with a case where a movement or the like of the outer object occurs.

  Here, as a simple example, a case where there is no indicator in the display area 5 (a case where there is no input by the indicator) will be described. When there is no indicator in the display area 5 but there is an outside object, as described above, the light is received by the line CCD with the infrared LED being projected in step S109. In this case, the light projection data has a light amount distribution as shown in FIG. Here, if the outer object is moved, for example, and the outer object no longer exists when viewed from the line CCD side, the region 402 where the amount of light in FIG. 4B is large disappears. In this case, the light amount distribution of the projection data is as shown in FIG. Therefore, it is obtained by subtracting the non-projection data (data of the light quantity distribution of FIG. 4A) from the light projection data (data having the light quantity distribution as shown in FIG. 4A) in step S110 described above. The total reflection component data is substantially zero (0) as shown in FIG.

  In step S111, when the input component data is calculated by subtracting the reference reflection component data (FIG. 4C) from the total reflection component data (FIG. 4G), the light quantity distribution as shown in FIG. Data will be obtained. That is, as shown in FIG. 4 (O), the light amount level of the region 409 corresponding to the region 402 shown in FIG. 4 (C) appears as a negative level.

  When the negative reflection level is generated in the input component data by subtracting the reference reflection component data from the total reflection component data in this way, the arithmetic control unit 3 updates the reference reflection component data in step S114. For example, when the position of the region 409 where the light amount level is negative as shown in FIG. 4 (O) is a position corresponding to the region 402 of FIG. 4 (C), the arithmetic control unit 3 in FIG. The reference reflection component data is updated with data obtained by subtracting the component value of the region 409 from the reference reflection component data. When the component value in the region 409 in FIG. 4 (O) is subtracted from the reference reflection component data in FIG. 4 (C) in this way, the positive region 402 in FIG. 4 (C) and the negative region 409 in FIG. 4 (O). Are canceled out, and the amount of light becomes almost zero (0) over the entire area as shown in FIG. Then, using the light amount distribution data as shown in FIG. 4G at this time, the reference reflection component data obtained immediately after power-on as described above is updated. Note that the update of the reference reflection component data is performed corresponding to each of the sensor unit 2a and the sensor unit 2b. Note that, according to the coordinate input device of the present embodiment, similarly, when background light such as an incandescent lamp changes, the background light component is canceled by the process of subtracting the non-projection data from the projection data in step S110. This can eliminate the effect.

<Coordinate conversion process when there is valid input>
After step S114, the arithmetic control unit 3 advances the process to step S115. In step S115, the arithmetic control unit 3 determines whether the above-described valid input has been detected in both the sensor units 2a and 2b. If the calculation control unit 3 determines in step S115 that a valid input is not detected in both the sensor units 2a and 2b or a valid input is detected only in one of them, the touched coordinates are calculated. Since it cannot be performed, the process returns to step S108. On the other hand, if the arithmetic control unit 3 determines in step S115 that a valid input has been detected in both the sensor units 2a and 2b, the process proceeds to step S116.

  In step S116, the arithmetic control unit 3 calculates an angle, described later, of the input position with respect to the sensor unit 2a and the sensor unit 2b from the pixel number corresponding to the valid input detected in both the sensor units 2a and 2b. Here, a table reference or a conversion formula is used for the conversion from the pixel number to the angle value. For example, a high-order polynomial can be used as the conversion formula to ensure accuracy, but the order and the like may be determined in consideration of calculation capability, accuracy specifications, and the like. In this embodiment, an example in the case of using a fifth order polynomial is shown. First, when the sensor bar 1 is assembled and manufactured, the relationship between the pixel number of each line CCD of the sensor units 2a and 2b and the angle is measured in advance. From these pixel number and angle measurement results, a coefficient for converting the pixel number into an angle value is obtained by fifth-order polynomial approximation. The coefficient data is stored in a nonvolatile memory or the like. If the pixel number is N, and the six coefficients of the fifth-order polynomial are L5, L4, L3, L2, L1, and L0, the angle value θ can be expressed as Equation (1).

  θ = L5 * N + L4 * N + L3 * N + L2 * N + L1 * N + L0 Equation (1)

  After step S116, the arithmetic control unit 3 advances the process to step S117. In step S117, the arithmetic control unit 3 calculates input coordinates using the angle θ calculated in step S116.

  Here, a coordinate system used when the calculation control unit 3 calculates input coordinates will be described. First, the origin, the x axis, and the y axis in the coordinate system are defined. As shown in FIG. 1, the origin is, for example, the center of the sensor unit 2a, and the coordinate value of the origin is (0, 0). The y-axis is an axis connecting the sensor unit 2b from the origin, and the x-axis is an axis perpendicular to the y-axis and along the whiteboard 4 (a direction substantially parallel to the whiteboard 4). The coordinate value of the center of the sensor unit 2b is set as (0, 1). And the calculation control part 3 determines the relative coordinate system based on the relative positional relationship of these sensor units 2a and 2b.

  Hereinafter, as shown in FIG. 1, for example, it is assumed that a touch with an indicator is performed at coordinates (x, y) (hereinafter referred to as touch coordinates (x, y)), and the touch coordinates (x, y) are input. The angle value θ with respect to the position and coordinate conversion will be described as an example. Here, the direction parallel to the x-axis of the sensor unit 2a is defined as a reference angle (0 degree), and the input position of the touch coordinates (x, y) when the sensor unit 2a detects the indicator and the reference angle are formed. The angle is θ1. Similarly, the direction parallel to the x-axis of the sensor unit 2b is defined as a reference angle (0 degree), and the input position of the touch coordinates (x, y) when the sensor unit 2b detects an indicator and the reference angle are formed. The angle is θ2. The calculation control unit 3 calculates the angle value θ described in step S116 described above to obtain the angle θ1 in the sensor unit 2a and the angle θ2 in the sensor unit 2b. Then, the arithmetic control unit 3 uses the angles θ1 and θ2 obtained for each of the sensor units 2a and 2b, and in step S117, the touch coordinates (in the relative coordinate system based on the relative positional relationship between the sensor units 2a and 2b) ( x, y) is calculated. More specifically, the relationship of Expression (2) is established between the angle θ1 detected by the sensor unit 2a and the touch coordinates (x, y).

  y = x × tan θ1 Formula (2)

  Similarly, Expression (3) is established between the angle θ2 detected by the sensor unit 2b and the touch coordinates (x, y).

  y−1 = x × tan θ2 Formula (3)

  For this reason, the calculation control unit 3 calculates the touch coordinates (x, y) by further performing the calculations of Expressions (4) and (5).

x = 1 / (tan θ1-tan θ2) Equation (4)
y = tan θ1 / (tan θ1-tan θ2) Equation (5)

  After step S117, operation control unit 3 advances the process to step S118. In step S118, the arithmetic control unit 3 converts the touch coordinates (x, y) calculated in step S117 into coordinate values on the display coordinate system of the display area 5. After step S118, the calculation control unit 3 outputs the data of the coordinate value to an external device such as the PC 10 in step S119. Thereafter, the arithmetic control unit 3 returns the process to step S108.

<Acquiring parameters for coordinate conversion by calibration>
Here, as a method of converting the touch coordinates (x, y) into coordinate values on the display coordinate system, there is a method such as projective conversion. Since coordinate transformation methods such as projective transformation are well known, detailed description is omitted here. Here, in order to perform coordinate conversion of touch coordinates (x, y) into coordinate values on the display coordinate system, parameters (such as values of elements of the coordinate conversion matrix) that associate the positional relationship between these two coordinate systems are required. Become. Hereinafter, an example of processing for setting this parameter will be described.

  As shown in FIG. 1, the display coordinate system in the display area 5 is, for example, a linear two-dimensional coordinate system including a dx axis and a dy axis with d1 as an origin. In the coordinate input device of this embodiment, in order to set parameters for coordinate conversion, for example, a process called so-called calibration is performed. In order to realize the calibration process, a dedicated application program (hereinafter referred to as a calibration application) is installed in the PC 10 that performs display control.

  When the calibration application is activated, the PC 10 displays a cross or the like on the display area 5 by display control of the front projector, and also displays a message for prompting the user to touch the cross position. Then, when the user performs a touch input to the cross or the like, the PC 10 acquires the coordinate value of the touch input position from the sensor bar 1. The PC 10 repeats such a cross cross display and acquisition of coordinate values of the user's touch input thereto for a predetermined number of times with different positions of the cross cross display. Then, the PC 10 sets a parameter in the sensor unit 2 such that the coordinate value of the relative coordinate system obtained by the predetermined number of times and the coordinate value of the display coordinate system of the cross-cross display position coincide with each other. Thus, when the touch coordinates (x, y) are coordinate-converted into coordinate values on the display coordinate system, the positional relationship between these two coordinate systems can be associated.

  In addition to the example in which the calibration process is performed by touching the display position of the cross, for example, the user is asked to touch the four corners of the display area 5, and the touch positions at the four corners and the coordinates of the four corners of the display area 5 are obtained. Based on the value. In the case of this example, by connecting to a PC on the spot, it is possible to obtain an excellent effect that it can be used immediately without installing special application software.

  In the case of this example, the coordinate input device shifts to the calibration mode by, for example, an operation of a mode change switch provided in the user interface 66 of the sensor bar 1. The processing in the calibration mode is performed, for example, immediately after the sensor bar 1 is installed on the whiteboard 4 or when the display position of the front projector or the installation position of the sensor bar 1 is deviated due to any beat after the sensor bar 1 is completely installed. To be done. When transitioning to the calibration mode, the arithmetic control unit 3 first performs the reference reflection component derivation process shown in FIG. This is because, for example, when the installation position of the sensor bar 1 is deviated, it is assumed that the position of the background light, the outside object, or the like changes when viewed from the sensor unit 2, and the above-described non-light-projecting background light or This is for updating information such as background light and reference reflection components.

  When the reference reflection component derivation process is completed in the calibration mode, the arithmetic control unit 3 performs the input detection process shown in FIG. Then, as described above, when the valid input is detected in step S115 and the input coordinate is calculated in step S117, the arithmetic control unit 3 stores the coordinate value in the memory 64. In the calibration mode, when notifying the user that the acquisition of the coordinate value data has been completed, for example, a beep sound is output from a speaker provided in the user interface 66, for example. Also good. Thereafter, the arithmetic control unit 3 returns the process to step S108 without executing the processes of steps S118 and S119.

  The arithmetic control unit 3 repeats each of these processes a number of times (four times) corresponding to the four corners of the display area 5. When the detection of the input corresponding to the four corners of the display area 5 and the calculation of the coordinate values are completed, the arithmetic control unit 3 calculates the parameters for the coordinate conversion as described above. As a result, four coordinate values corresponding to the four corners of the display area 5 are acquired on the relative coordinate system and the display coordinate system, respectively. For example, coordinate conversion can be performed by a method such as projective conversion. Parameters (values of transformation matrix elements) can be calculated. After calculating the parameters in this way and storing them in the memory 64, the arithmetic control unit 3 ends the calibration mode. Note that the parameters calculated in the calibration mode are thereafter used in the coordinate conversion in step S118 described above.

<Effect of the first embodiment>
As described above, in the coordinate input device according to the first embodiment, the processing from step S108 to step S114 is performed in particular, so that the ambient light component included in the light amount distribution detected by the line CCD, the outer object, etc. The influence of the reflected light component from can be eliminated. For this reason, according to the present embodiment, even if the touch position by the pointing object is a position overlapping with ambient light or reflected light from an outside object as viewed from the line CCD, for example, it is possible to reliably detect an effective input. Can do. Further, according to the present embodiment, it is possible to reliably detect an effective input even when ambient light, reflected light from an external object, or the like changes.

<Second Embodiment>
Next, as a second embodiment, a retroreflective material that recursively reflects the light emitted from the infrared LED of the sensor unit 2 is provided, and the retroreflected light from the retroreflective material is reflected by the line CCD of the sensor unit 2. A coordinate input device adopting an optical light shielding method for receiving light will be described.

  The configuration of the coordinate input device of the second embodiment is substantially the same as the configuration of FIG. 1, but in the case of the optical shading method, the side portion corresponding to the sensor unit 2 side in the peripheral portion of the whiteboard 4 is arranged. Retroreflective material is installed. As in the example of FIG. 1, when the sensor unit 2 is disposed at the lower left corner of the whiteboard 4, the retroreflective members 101 and 102 are installed along the upper and right sides of the whiteboard 4. In the example of FIG. 1, retroreflective materials 101 and 102 are installed in the portion indicated by the alternate long and short dash line in the drawing.

  In the case of the configuration example of the second embodiment, the light projected from the infrared LED inside the sensor unit 2 toward the display region 5 is retroreflected by the retroreflective members 101 and 102, and the sensor unit 2 is reflected. Come back to. The line CCD in the sensor unit 2 receives the retroreflected light. Here, when an input by an indicator such as a finger is made in the display area 5, the retroreflected light from the retroreflective members 101 and 102 is blocked by the indicator. For this reason, the light reception signal of the line CCD is a signal of a light amount distribution in which the light amount in the region where the retroreflected light is blocked by the indicator is reduced. Accordingly, the pixel number of the area where the light amount is reduced due to the light received from the line CCD is obtained, and the angle is calculated as described above based on the pixel number, so that the touch input position by the pointer is determined. Can be sought. The detailed configuration and calculation processing such as position detection and coordinate value calculation in the optical shading method are disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 2004-133620, and therefore description thereof is omitted here.

  In the second embodiment, the flow of the reference reflection component derivation process in which the arithmetic control unit 3 of the coordinate input device executes the control program is substantially the same as the flowchart shown in FIG. In addition, the flow of the input detection process which the calculation control part 3 of the coordinate input device performs in 2nd Embodiment becomes like the flowchart of FIG. First, reference reflection component derivation processing in the second embodiment will be described with reference to FIG.

<Reference reflection component derivation processing of the second embodiment>
In step S102, the arithmetic control unit 3 initializes peripheral circuits such as input / output port setting, timer setting initialization, line CCD charge accumulation reset, and the like. Next, in step S103, the arithmetic control unit 3 performs light reception by the line CCD in each sensor unit 2 with the infrared LEDs of the sensor units 2a and 2b turned off in the same manner as in the first embodiment. . The light reception signals of the line CCDs of the sensor units 2a and 2b are respectively digitized by the A / D converter 63 and stored in the memory 64 as non-projected background light data.

  FIG. 6A is a diagram illustrating an example of a graph of the light amount distribution of the non-projection background light data. In FIG. 6A and FIGS. 6B to 6K described later, the horizontal axis is the pixel number of the line CCD, and the vertical axis is the amount of light. The above-described FIGS. This is the same as the example (O). Here, in the case of the non-projection background light data illustrated in FIG. 6A, there is a region 601 where the light amount is large near the center of the horizontal axis. The region 601 where the amount of light is large is caused by the fact that, for example, infrared light included in ambient light from an incandescent lamp or the like enters the line CCD as background light and is received.

  In the next step S104, the calculation control unit 3 causes each line CCD in each of the sensor units 2 to receive light while the infrared LEDs of both of the sensor units 2a and 2b are turned on. The light reception signals of the line CCDs of the sensor units 2a and 2b are digitized by the A / D converter 63 and stored in the memory 64 as projected background light data.

  FIG. 6B is a diagram illustrating an example of a graph of the light amount distribution of the projection background light data. In the case of the light quantity distribution of the projected background light data illustrated in FIG. 6B, the light quantity is further increased in the horizontal axis by the retroreflected light from the retroreflective materials 101 and 102 in the region 601 where the light quantity is increased by the ambient light. A region 602 is added which is enlarged over a wide range.

  In the next step S105, the arithmetic control unit 3 subtracts the non-projection background light data in FIG. 6 (A) from the projection background light data in FIG. 6 (B) stored in the memory 64, respectively. Thereby, data consisting of retroreflective light components from the retroreflective materials 101 and 102 is obtained. In the second embodiment, the light amount component (data of only the retroreflected light component) after subtracting the non-projected background light data from the projected background light data is the reference reflected component.

  FIG. 6C is a graph showing the light amount distribution (reference reflection component) after subtracting the non-projected background light data of FIG. 6A from the projected background light data of FIG. 6B. is there. The light amount distribution (reference reflection component) illustrated in FIG. 6C includes a region 602 in which the light amount is increased over a wide range of the horizontal axis due to retroreflected light from the retroreflective materials 101 and 102. When the calculation control unit 3 stores the reference reflection component data in the memory 64, the calculation control unit 3 ends the reference reflection component derivation process in the second embodiment.

<Input Detection Processing of Second Embodiment (when the pointing object is at a position that does not overlap with background light)>
Hereinafter, the flow of processing executed by the arithmetic control unit 3 when detecting the input by the indicator to the display area 5 after the above-described reference reflection component derivation processing is completed will be described with reference to the flowchart of FIG. . First, the flow of processing when an input by an indicator is performed at a position that does not overlap with background light when viewed from each line CCD of each sensor unit 2 will be described.

  In the flowchart of FIG. 5, first, as a process of step S <b> 202, the arithmetic control unit 3 receives light by each line CCD in a state where each infrared LED of each sensor unit 2 is turned off, and acquires non-light projection data. . The light amount distribution of the non-projection data in the case of the second embodiment is substantially the same as the light amount distribution illustrated in FIG. 6A described above because there is no infrared LED projection and no retroreflected light. Become. The arithmetic control unit 3 stores the non-light projection data in the memory 64. After step S202, the arithmetic control unit 3 advances the process to step S203.

  In step S <b> 203, the arithmetic control unit 3 receives light by each line CCD in a state where each infrared LED of each sensor unit 2 is projected, and acquires projection data. FIG. 6D is a diagram illustrating an example of the light amount distribution of the projection data when the indicator is present at a position that does not overlap with the background light in the second embodiment. In the case of the example in FIG. 6D, compared with the example in FIG. 6B, the amount of light is reduced by the retroreflected light being blocked by the indicator in the region 603 near the left end of the horizontal axis that does not overlap with the background light. A region where a drop has occurred appears. The arithmetic control unit 3 stores the light projection data in the memory 64. After step S203, the arithmetic control unit 3 advances the process to step S204.

  In step S204, the arithmetic control unit 3 subtracts the non-projection data similar to that in FIG. 6A from the projection data in FIG. 6D stored in the memory 64, and the data after the subtraction. Is obtained as total reflection component data.

  FIG. 6E is a graph showing the light amount distribution of the total reflection component data after subtracting the non-light projection data similar to FIG. 6A from the light projection data of FIG. 6D. The amount of light distribution of the total reflection component data illustrated in FIG. 6E includes an area 602 due to retroreflective light components, and an area 603 in which the amount of light is reduced due to the retroreflected light being blocked by an indicator near the left end of the horizontal axis. The distribution has The arithmetic control unit 3 stores the total reflection component data in the memory 64, and then advances the process to step S205.

  In step S205, the calculation control unit 3 obtains a difference between the reference reflection component data shown in FIG. 6C and the total reflection component data shown in FIG. 6E, and uses the data after the difference calculation as an input component. Get as data. In the case of the second embodiment, the total reflection component data is subtracted from the reference reflection component data as a difference calculation between the reference reflection component data and the total reflection component data shown in FIG.

  FIG. 6F is a graph showing the light amount distribution of the input component data after subtracting the total reflection component data shown in FIG. 6E from the reference reflection component data shown in FIG. 6C. is there. In the light amount distribution illustrated in FIG. 6F, there is a region 604 where the value is large near the left end of the horizontal axis. In the example of FIG. 6F, the light amount level in this region 604 corresponds to the light amount level that is reduced by the retroreflected light of the infrared light projected from the sensor unit 2 being blocked by the indicator. Conceivable. The arithmetic control unit 3 stores the input component data in the memory 64, and then proceeds to step S206.

  In step S <b> 206, the arithmetic control unit 3 detects whether there is an effective input component that can be determined to be input by the indicator in the input component data. Specifically, as in the case of the first embodiment described above, the arithmetic control unit 3 obtains the peak of the light amount in the input component, and is effective if the peak value is greater than the predetermined first threshold value TH1. Such as determining that the input component is a correct input component. In the example of FIG. 6F, the peak value of the region 604 where the light amount is large near the left end of the horizontal axis is larger than the first threshold value TH1, and the peak is at one place. 3 determines that there is an effective input component by one indicator. Then, the arithmetic control unit 3 obtains each pixel number corresponding to the peak position among the pixel numbers of the line CCDs of the sensor units 2a and 2b, and stores the data of these pixel numbers in the memory 64.

<Input Detection Processing of Second Embodiment (when there is no indication in the display area)>
In the second embodiment, when there is no indication in the display area 5, the data in steps S102 to S206 in FIG.

  When there is no indicator in the display area 5 in the second embodiment, the light quantity distribution of the non-projection data when the light is received by the line CCD with the infrared LED turned off in step S202 is as described above. This is substantially the same as FIG. Next, in step S203, the light quantity distribution of the light projection data when light is received by the line CCD with the infrared LED being projected is substantially the same as that in FIG.

  Accordingly, the total reflection component data obtained by subtracting the non-projection data in FIG. 6A from the projection data in FIG. 6B in step S204 is the same as the reference reflection component data in FIG. 6C. In step S205, the light amount distribution of the input component data calculated by subtracting the total reflection component data (the same light amount distribution data as in FIG. 6C) from the reference reflection component data (FIG. 6C) is: As shown in FIG. 6G, it is substantially zero (0) over the entire area. In the case of the example of FIG. 6G, since there is no peak portion exceeding the first threshold value TH1 in the input component, the calculation control unit 3 determines whether there is a valid input in step S206. It will be judged that there is no input.

<Input Detection Processing of Second Embodiment (When Pointed Object is Overlaid with Background Light)>
In the second embodiment, when there is an indicator at a position overlapping the background light when viewed from the line CCD side of the sensor unit 2, the data in steps S202 to S206 in FIG. 5 are as follows.

  In the second embodiment, when there is an indicator at a position overlapping the background light when viewed from the line CCD side, no light projection is performed when light is received by the line CCD with the infrared LED turned off in step S202. The light quantity distribution of data is as shown in FIG. In this case, there is an indicator at a position overlapping with the background light, and the background light is partially blocked by the indicator, so that the light quantity distribution of the non-projection data is as shown in FIG. A part of the background light region 601 in (A) is blocked by the indicator, resulting in a distribution having a region 605 in which the amount of light is reduced.

  Next, in step S203, the light quantity distribution of the light projection data when light is received by the line CCD with the infrared LED being projected is as shown in FIG. In this case, the light projected from the infrared LED is retroreflected by the retroreflective materials 101 and 102, while the retroreflected light is blocked by the indicator at a position overlapping the background light. In this case, as shown in FIG. 6 (I), the light quantity distribution of the light projection data is such that the area 601 where the light quantity by the background light is large and the area 602 where the light quantity by the retroreflected light are overlapped, while the retroreflected light by the indicator. Is a distribution in which a region 606 in which the amount of light is reduced due to being blocked. Note that the light amount level of the region 606 at this time is considered to be the light amount level of the reflected light obtained by reflecting the infrared light projected from the infrared LED by the indicator.

  In step S204, the light quantity distribution of the total reflection component data obtained by subtracting the non-light projection data of FIG. 6A from the light projection data of FIG. 6I is as shown in FIG. In FIG. 6J, the light quantity distribution of the total reflection component data includes an area 602 where the light quantity due to the retroreflective light component is large, and an area 606 where the light quantity is reduced by the retroreflected light being blocked by the indicator. Distribution. Therefore, in step S205, the light quantity distribution of the input component data obtained by subtracting the total reflection component data of FIG. 6 (J) from the reference reflection component data of FIG. 6 (C) is as shown in FIG. 6 (K). As shown in FIG. 6 (K), the light quantity distribution of the input component data has a light quantity level that is reduced by the retroreflected light of the infrared light projected from the sensor unit 2 being blocked by the indicator. Only the corresponding peak level region 607 remains.

  Thereafter, in step S206, the arithmetic control unit 3 detects whether there is a valid input based on the input component data of the light quantity distribution as shown in FIG. In the example of FIG. 6K, the light intensity peak of the region 607 due to the light projected from the infrared LED reflected by the indicator is larger than the first threshold value TH1, and the peak is at one location. Therefore, the arithmetic control unit 3 determines that there is one valid input from one indicator. Then, the arithmetic control unit 3 obtains each pixel number corresponding to the peak position among the pixel numbers of the line CCDs of the sensor units 2a and 2b, and stores the data of these pixel numbers in the memory 64.

  As described above, the coordinate input device according to the second embodiment performs the processing in steps S202 to S206 in FIG. 5 even when the indicator is present at a position overlapping the background light as viewed from the line CCD side. It is possible to reliably detect a valid input by the indicator. In the case of the coordinate input device according to the second embodiment, the arithmetic control unit 3 determines that touchdown has been performed at the peak position of the valid input when a valid input is detected in step S206.

  5 is the same as step S115 in FIG. 3B, and the process in step S208 in FIG. 5 is the same as step S116 in FIG. Similarly, the process in step S209 in FIG. 5 is the same as step S117 in FIG. 3B, the process in step S210 in FIG. 5 is the same as that in step S118 in FIG. 3B, and the process in step S211 in FIG. This is the same as step S119 in FIG. Then, after step S211 in FIG. 5, the process returns to step S202. As described above, the processes in steps S207 to S211 in FIG. 5 are the same as those in steps S115 to S119 in FIG. 3B, and thus detailed description thereof will be omitted.

  Also in the second embodiment, when background light such as an incandescent lamp changes, the background light component is canceled by subtracting the non-projection data from the projection data in step S204. The influence can be eliminated.

<Effects of Second Embodiment>
As described above, the coordinate input device according to the second embodiment that employs the optical shading method is similar to the first embodiment described above in that the ambient light component included in the light amount distribution detected by the line CCD is detected. The influence can be eliminated. For this reason, according to the second embodiment, even if the touch position by the pointing object is a position overlapping the ambient light as viewed from the line CCD, for example, it is possible to reliably detect an effective input. Further, according to the second embodiment, it is possible to reliably detect an effective input even when the position or the amount of ambient light changes.

<Other embodiments>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  1 sensor bar, 2 (2a, 2b) sensor unit, 3 arithmetic control unit, 4 whiteboard, 5 display area, 10 PC (personal computer), 61 CPU, 64 memory

Claims (7)

A light projecting means for projecting light in a direction along the coordinate input surface;
At least two light receiving means capable of receiving light from a direction along the coordinate input surface;
A first light receiving signal generated based on light received by the light receiving means when no light is projected by the light projecting means when there is no indicator on the coordinate input surface; and the coordinates This is a difference from a second received light signal generated based on the light received by the light receiving means when light is projected by the light projecting means when there is no indicator on the input surface. Deriving one component,
The third light receiving signal generated based on the light received by the light receiving means when no light is projected by the light projecting means, and the first light receiving signal after the first and second light receiving signals are generated. Deriving means for deriving a second component that is a difference from a fourth light receiving signal generated based on light received by the light receiving means when light projecting by the light projecting means is performed;
Detecting means for detecting an input to the coordinate input surface by an indicator based on a difference between the first component and the second component;
A coordinate input device, comprising: a calculating unit that calculates a position of the detected input on the coordinate input surface when an input to the coordinate input surface by an indicator is detected by the detection unit.   The calculation means calculates a coordinate value on the coordinate input surface for the difference peak when a difference peak value between the first component and the second component exceeds a predetermined threshold. The coordinate input device according to claim 1, wherein the coordinate input device calculates the coordinate input device.   When the peak value in the fourth received light signal corresponding to the peak of the difference between the second component and the first component exceeds a predetermined threshold, the calculating means The coordinate input device according to claim 1, wherein a coordinate value on the coordinate input surface is calculated with respect to a peak in the four received light signals. Storing means for storing the first component;
The derivation means, when the component after subtracting the first component stored by the storage means from the second component includes a negative component, the first component stored by the storage means The coordinate input device according to claim 1, wherein the coordinate input device is updated. The light projecting means projects light to the retroreflective means disposed on the periphery of the coordinate input surface,
The coordinate input device according to claim 1, wherein the light receiving unit receives light reflected by the retroreflective unit. A control method for a coordinate input device, comprising: light projecting means for projecting light in a direction along the coordinate input surface; and at least two light receiving means capable of receiving light from the direction along the coordinate input surface,
A first light receiving signal generated based on light received by the light receiving means when no light is projected by the light projecting means when there is no indicator on the coordinate input surface; and the coordinates This is a difference from a second received light signal generated based on the light received by the light receiving means when light is projected by the light projecting means when there is no indicator on the input surface. Deriving one component,
The third light receiving signal generated based on the light received by the light receiving means when no light is projected by the light projecting means, and the first light receiving signal after the first and second light receiving signals are generated. A derivation step for deriving a second component that is a difference from a fourth light receiving signal generated based on the light received by the light receiving means when the light projecting means performs light projection;
A detection step of detecting an input to the coordinate input surface by an indicator based on a difference between the first component and the second component;
And a calculation step of calculating a position of the detected input on the coordinate input surface when an input to the coordinate input surface by the indicator is detected by the detection step. . A computer of a coordinate input device, comprising: a light projecting unit that projects light in a direction along the coordinate input surface; and at least two light receiving units that can receive light from the direction along the coordinate input surface.
A first light receiving signal generated based on light received by the light receiving means when no light is projected by the light projecting means when there is no indicator on the coordinate input surface; and the coordinates This is a difference from a second received light signal generated based on the light received by the light receiving means when light is projected by the light projecting means when there is no indicator on the input surface. Deriving one component,
The third light receiving signal generated based on the light received by the light receiving means when no light is projected by the light projecting means, and the first light receiving signal after the first and second light receiving signals are generated. Deriving means for deriving a second component that is a difference from a fourth light receiving signal generated based on light received by the light receiving means when light projecting by the light projecting means is performed;
Detecting means for detecting an input to the coordinate input surface by an indicator based on a difference between the first component and the second component;
A program for functioning as a calculation means for calculating a position of the detected input on the coordinate input surface when an input to the coordinate input surface by an indicator is detected by the detection means.

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