JP4423113B2 - Coordinate input device, control method therefor, and program - Google Patents

Description

  The present invention relates to a coordinate input device that inputs coordinates by designating a coordinate input surface with a finger or an indicator, and more specifically, a coordinate input device used for drawing characters, figures, etc., controlling external devices, and the like. And a control method thereof.

  2. Description of the Related Art Conventionally, coordinate input devices using various touch panels have been proposed or commercialized as coordinate input devices that perform coordinate input with a finger or an indicator. Coordinate input devices are widely used because operations of a personal computer (PC) or the like can be easily performed on the coordinate input surface without using a special instrument or the like.

  As the coordinate input method, there are various methods such as a method using a resistive film, a method using ultrasonic waves, and a method using light. As a method using light, a retroreflective sheet (retroreflective member) is provided outside the coordinate input surface, the light from the illumination unit is reflected by the retroreflective member, and the light amount distribution is detected by the light receiving unit. A device that detects the angle of a position shielded by a finger or pointing tool on a coordinate input surface and determines the coordinates of the shielding position, that is, the pointing input position is known (for example, see Patent Document 1).

  Furthermore, an apparatus has been developed in which a retroreflective member is arranged around the coordinate input surface to detect the coordinates of a portion where the retroreflected light from the retroreflective member is shielded. For example, there is a method of detecting the angle of the light-shielding portion by detecting the peak of the light-shielding portion by waveform processing calculation such as differentiation (see, for example, Patent Document 2). Alternatively, there is a method in which one end and the other end of the light-shielding portion are detected by comparison with a specific level pattern, and the center of those coordinates is detected (see, for example, Patent Document 3).

  Here, a schematic configuration of the above-described optical coordinate input device will be described with reference to FIG.

  FIG. 27 is a configuration diagram showing a schematic configuration of a coordinate input device according to a conventional example.

  In FIG. 27, the sensor unit 101L and the sensor unit 101R are arranged outside the corner of the coordinate input effective area 103 at a predetermined distance at a position parallel to the X axis of the coordinate input effective area 103 and symmetrical with respect to the Y axis. Has been. The sensor unit 101L and the sensor unit 101R include a light projecting unit and a detection unit, receive a control signal from the control / arithmetic unit 102, and detect a detection signal based on detection of reflected light by the detection unit. Send to. In the following description of each drawing, the left and right sensor units 101L and 101R are also collectively referred to as the sensor unit 101. Moreover, the line with an arrow in each following figure shows a light ray.

  The retroreflective member 104 has a retroreflective surface that retroreflects incident light in the direction of arrival, and the light projected from the light projecting portions of the left and right sensor units 101 within a range of approximately 90 degrees is used as a sensor. Retroreflects toward the unit 101. The reflected light reflected by the retroreflective member 104 is one-dimensionally detected by a detection unit including a condensing optical system and a line CCD in the sensor unit 101, and the light quantity distribution of the reflected light is sent to the control / arithmetic unit 102. . The coordinate input effective area 103 is an area in which the position designated by the coordinate input device with a finger or an indicator can be detected, and is schematically shown. The retroreflective member 104 is arranged so as to surround the three outer sides of the coordinate input effective area 103.

  In the above configuration, when the operator inputs an arbitrary position on the coordinate input effective area 103 with a finger or an indicator, the light projected from the light projecting unit of the sensor unit 101 is blocked by the finger or the indicator, and the sensor The detection unit of the unit 101 cannot detect light only in the light shielding range (reflected light due to retroreflection). As a result, it is possible to determine from which direction the light could not be detected.

  That is, the arithmetic control unit of the control / arithmetic unit 102 detects the light shielding range of the indicated portion from the light amount change detected by the detection units of the left and right sensor units 101L and 101R, and the direction of the light shielding position from the information on the light shielding range. (Angle) is calculated respectively. Further, the arithmetic control unit calculates the coordinates of the indicated portion on the coordinate input effective area 103 from the calculated direction (angle), the distance information between the sensor units 101L and 101R, etc., and arranges them on the coordinate input device. The coordinate information is output to a PC or the like connected to the display device via an interface such as USB (Universal Serial Bus).

  As the retroreflective member 104, bead-type retroreflective sheets having retroreflective properties by arranging spherical beads on the reflective surface, or corner cubes that are optical reflective surfaces are regularly arranged by machining or the like. A retroreflective sheet that causes a recursive phenomenon is used. For this reason, if dust or the like adheres to the surface of the retroreflective member 104, the retroreflective efficiency clearly decreases. Therefore, when this type of coordinate input device is actually supplied to the market as a product, it is necessary to have a configuration in which the retroreflective characteristics of the retroreflective member 104 do not change. Even if the retroreflective characteristic changes during use of the coordinate input device for some reason, the user can easily return the retroreflective characteristic to the original state. There must be.

  Now, assuming that dust or the like has adhered to the retroreflective member 104 of the coordinate input device in the market and the retroreflective characteristics have changed, the user generally performs a “wiping” operation to remove the dust. . However, this “wiping” operation is not recommended because it damages the retroreflective surface with optical properties. In general, it can be said that it is preferable to blow a gas such as air as a treatment for removing dust on the optical surface. However, this type of coordinate input device is usually used in, for example, a meeting at a business office, etc., and it is never preferable for a user to interrupt the meeting and perform maintenance such as air blowing as described above. It is not a form.

  FIG. 28A is a diagram showing a state in which the coordinate input effective area of the coordinate input device is substantially matched with the display area of the display device, and FIG. 28B is an enlarged view of the area A in FIG. is there.

  In FIG. 28, the illustrated configuration shows an example of a product when an optical coordinate input device is arranged so as to overlap with a display device (for example, a rear projector, a PDP (Plasma Display Panel), etc.). The coordinate input effective area 103 is substantially the same as the display area of the display device. Here, when the display area of the display device is 1330 × 750 mm (diagonal 60 inches, aspect ratio equivalent to 16: 9), the housing 107 has a slightly larger opening (for example, 1350 mm × 770 mm) than the display area. It is usual to provide.

  This is because there is an inter-individual difference in the size of the display area of the display device (particularly apparent in display devices using a projection optical system such as a rear projector), and there is no inter-individual difference. Even in the product specification in which the display area is equal to the housing opening, it is essential to perform assembly adjustment so that the display area matches the housing opening. The fact that the assembly adjustment is shifted or cannot be adjusted causes a serious result that a part of the display area is hidden by the housing 107 and the entire display area cannot be viewed.

  Therefore, by making the opening of the housing 107 one size larger than the display area, the individual differences are absorbed and the production process such as assembly adjustment is simplified. Therefore, as shown in FIG. 28 (a), a frame-like region 109 is formed between the display region (in this case, substantially equal to the coordinate input effective region 103) and the opening of the housing 107 (hereinafter, referred to as “the frame input region 103”). This frame-like region is called a black frame).

  As shown in FIG. 28 (b), the display surface having the coordinate input effective area 103 (= substantially display area) is disposed with respect to the housing 107 via the light transmitting member 108, and also transmits light. A retroreflective member 104 is disposed on the back side of the member 108. The light transmissive member 108 can be easily constructed of not only glass but also hard plastic, and is less likely to be scratched compared to the retroreflective member 104 even when the user performs a “wiping” operation. Therefore, by adopting such a configuration, “dust”, “dust”, and the like that will accumulate on the light transmitting member 108 can be easily removed by the user, and a user-friendly product can be used with high reliability. Will be able to continue.

  As described above, it has been described that by incorporating the light transmitting member 108 in the coordinate input device, the appearance of the product can be improved and maintenance can be facilitated. However, a new problem occurring here will be described. As described above, the use of specific dimensions makes it easier to understand, and therefore, description will be made with reference to FIG.

  FIG. 29A is an enlarged view of the region B in FIG. 28A, and FIG. 29B is an enlarged view of the region C in FIG.

  In FIG. 29, the width of the black frame 109 defined by the positional relationship between the coordinate input effective area 103 and the light transmitting member 108 is set to 10 mm. At this time, the sensor unit 101 arranged on the right side is arranged at a position 70 mm above the horizontal plane of the coordinate input effective area 103 and 7 mm on the right side from the end of the coordinate input effective area 103. Assume (therefore, the distance between the sensor unit 101 and the light transmission member 108 is 3 mm).

  Assume that a finger or an indicator 105 is placed in the lower right part of the coordinate input effective area 103. In the coordinate input device, the light emitted from the light projecting unit of the sensor unit 101 is configured to project the entire coordinate input effective area 103. The sensor unit 101 detects the presence of the finger or the pointing tool 105 at a position in the direction of the light D by shielding a part of the light (for example, the light D shown in FIG. 29B) with the finger or the pointing tool 105. Basically.

  FIG. 30 is a diagram showing the corners of the coordinate input effective area in the area C part of FIG.

In FIG. 30, the sensor unit 101 is arranged in the same manner as in FIG. 29A, and the reference angle (0 degree) of the sensor unit 101 is provided in the 45 degree direction from the horizontal direction. Here, if the diameter of the pointing tool 105 is 10φ, the angle to be detected by the light beam H when the corner of the coordinate input effective area 103 is pointed by the pointing tool 105 is 44.86 degrees. On the other hand, if the field stop is set so as not to be affected by the light transmitting member 108a, the effective light beam is the light beam in the I direction, and the angle to be detected is 45.14 degrees. Therefore, it is necessary to provide a field stop that can detect at least 44.86 degrees and cannot detect at least 45.14 degrees.
US patent USP 4507557 JP 2000-105671 A JP 2001-142642 A

  However, in the example shown in FIG. 29, the light beam projected in the E direction from the light projecting portion of the sensor unit 101 is reflected at the point F by the light transmitting member 108 and is projected in the E direction. Nevertheless, it reaches point G. That is, since the incident angle of the light beam in the E direction with respect to the light transmitting member 108a at the point F is large, the light beam in the E direction cannot be transmitted through the light transmitting member 108a but is reflected on the surface of the light transmitting member 108. It arrives.

  The light beam at the point G has a small incident angle with respect to the light transmitting member 108b, and therefore passes through the light transmitting member 108b, reaches the retroreflective member 104b, and is retroreflected in the direction of the point F. The retroreflected light beam has a large incident angle with respect to the light transmitting member 108a at the point F, and therefore most of the light cannot be transmitted through the light transmitting member 108a and is reflected and reaches the sensor unit 101.

  Therefore, the optical path of the light beam in the E direction projected from the light projecting unit of the sensor unit 101 is as follows: light projecting unit → F point (transmission) → E point (retroreflection) → F point (transmission) → sensor unit 101 Should be. However, due to the arrangement of the light transmitting member 108a, the light from the light projecting portion of the sensor unit 101 is reflected by the light projecting portion → F point (reflected) → G point (transmitted through the light transmitting member 108b and retroreflected by the retroreflective member 104b. The light path is again transmitted through the light transmitting member 108 b) → F point (reflection) → sensor unit 101.

  If the pointing tool 105 is arranged in the coordinate input effective area 103 as shown in FIG. 29B, the virtual image of the pointing tool 105 results in shielding the light projected in the E direction, and the coordinate calculation accuracy is improved. Causes significant deterioration.

  Such a phenomenon can be easily understood if it is assumed that the user wants to see the water from above the water surface. In other words, if you try to see the bottom of the water from directly above the water surface (incident angle is small), you can easily observe the bottom of the water, but if you try to see the bottom of the water from above the water surface (large incident angle), A phenomenon similar to that the observation becomes almost impossible also occurs in the coordinate input device.

  As shown in FIG. 29B, when the incident angle at the point F reaches 89.6 degrees, even if the material constituting the light transmitting member 108 is changed or the reflection surface is subjected to a treatment such as coating. No effect on light transmission can be expected. The above problem can be improved by making the incident angle at the point F smaller. However, this results in a significant increase in the width of the black frame 109, which leads to a very large size of the entire apparatus relative to the display area of the display apparatus or the coordinate input effective area 103 of the coordinate input apparatus. It's not a good way.

  On the other hand, as a general method for removing the influence of the virtual image, there is known a method of limiting the light projection range by the light projecting unit of the sensor unit 101 by a diaphragm or the like. The difficulty of this method will be described below. .

  That is, in the example shown in FIG. 30, setting the field stop to 45 ° ± 0.05 ° by design, for example, not only increases the cost of the parts, but also the sensor unit 101 has the correct orientation. It is meaningless if it is not attached to be. This is because the direction in which the angle formed with the horizontal direction is 45 degrees has been described as the reference direction of the sensor unit 101. This means that the reference direction is absolutely correct, and the distance between the sensor units (101L and 101R in FIG. 27). When the distance between them is 1344 mm, for example, it means that it is not easy to assemble the reference angles of the two with a tolerance of ± 0.05 degrees, for example.

  Therefore, when manufacturing the coordinate input device, an expensive assembly process must be assumed. In other words, conventionally, an adjustment means is indispensable for restricting the field of view of a coordinate input device arranged on this type of large display device, which is not easy in terms of manufacturing and cost.

  An object of the present invention is to provide a coordinate input device and a control method for the coordinate input device that can eliminate the influence of a virtual image generated by the installation of a light transmissive member that protects the retroreflective member and perform highly accurate coordinate calculation.

In order to achieve the above object, a coordinate input device of the present invention includes a coordinate input effective area, a retroreflective member disposed outside the coordinate input effective area, the retroreflective member, and the coordinate input effective area. A projection member that projects light over the entire surface direction of the coordinate input effective area, and the light projected by the projection unit is retroreflected by the retroreflective member and retroreflected. and a coordinate input device provided with a detecting means for detecting by a photoelectric conversion element with light, the reflection characteristic of the end portion of the retroreflective material in the light amount distribution of the initial state detected by the detecting means as the feature point Extracting means for extracting, setting means for setting an effective area of a signal output by the detecting means from the pixel number of the photoelectric conversion element corresponding to the feature point extracted by the extracting means, and the setting means And based on the signal of the set effective area to detect the angle from the detecting means of the indication position relative to the coordinate input effective region by, calculates the coordinates of the designated position relative to the coordinate input effective region based on the said angle and calculating means, characterized in that it comprises a.

  According to the present invention, the feature point of the light amount distribution in the initial state is extracted, the effective area of the signal output from the detection means is set from the pixel number of the feature point, and the coordinate input effective area is determined based on the signal of the effective area. The angle of the designated position is detected, and the coordinates of the designated position are calculated based on the angle. As a result, the influence of the virtual image can be removed and a highly accurate coordinate calculation can be performed without providing a high-cost field stop for removing the influence of the virtual image as in the prior art without fine adjustment.

  Further, according to the present invention, the effective area of the signal output from the detection means is set from the detection result of the light amount distribution obtained with the instruction input to the predetermined position, and the predetermined coordinate input effective area is determined based on the signal of the effective area. The angle of the position is detected, and the coordinates of the predetermined position are calculated based on the angle. As a result, as described above, the influence of the virtual image can be removed, and coordinate calculation with high accuracy becomes possible.

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

[First Embodiment]
FIG. 1 is a configuration diagram showing a schematic configuration of a coordinate input device according to a first embodiment of the present invention.

  In FIG. 1, a coordinate input device includes a left sensor unit 1L having a light projecting unit and a detection unit, a right sensor unit 1R having a light projecting unit and a detection unit, a control / calculation unit 2, and a coordinate input effective area. 3, a retroreflective member 4, and a light transmissive member 8. Light is projected from different directions over the entire surface direction of the coordinate input effective area 3 by the sensor unit 1L and the sensor unit 1R. In the following description of each figure, the left and right sensor units 1L and 1R are collectively referred to as sensor unit 1 as well.

  This embodiment is different from the configuration shown in FIG. 27 in that a light transmitting member 8 is added and various control described later is performed by the control / arithmetic unit 2. The other elements of the present embodiment are the same as the corresponding ones in FIG.

  The light transmissive member 8 can transmit only light of a specific wavelength, prevents unnecessary light from being transmitted, and prevents the retroreflective member 4 from being directly exposed to the outside. A part of the product appearance is configured by being arranged in the vicinity. With this configuration, “dust” and “dust” that accumulate when the coordinate input device is used as a product accumulates on the light transmitting member 8, and the user “wipes” the light transmitting member 8. It can be easily removed by such operations. As a result, it becomes easy to maintain the optical characteristics of the retroreflective member 4 semi-permanently, and a highly reliable coordinate input device can be realized.

  The coordinate input device can be used as an interactive input device by arranging the coordinate input effective region 3 on the display device so as to substantially coincide with the display region of the display device such as a PDP, a rear projector, or an LCD panel. Is possible. That is, a line may be drawn with a finger or an indicator on the display screen when the coordinate input device is placed on the display device, or an external device such as a PC may be controlled by an icon operation on the display screen. It becomes possible.

  Next, the configuration and operation of the sensor unit 1 and the control / arithmetic unit 2 which are main components of the coordinate input device will be described in detail.

<Sensor unit 1>
2A is a diagram of the light projecting unit of the sensor unit 1 of the coordinate input device viewed from the direction perpendicular to the coordinate input surface (front direction), and FIG. 2B is the coordinate input surface. It is the figure seen from the horizontal direction (side surface direction).

  In FIG. 2, the light projecting unit of the sensor unit 1 includes an infrared LED 31 and a light projecting lens 32. Infrared light emitted from the infrared LED 31 is projected in a range of approximately 90 degrees by the light projecting lens 32. In the horizontal direction shown in FIG. 2B, the infrared light emitted from the infrared LED 31 is projected as a light beam restricted in the vertical direction, and is projected mainly to the retroreflective member 4. It is configured. In the figure, 33 is an adhesive that bonds the infrared LED 31 and the light projecting lens 32.

  3A is a diagram of the detection unit of the sensor unit 1 viewed from the direction perpendicular to the coordinate input surface (front direction), and FIG. 3B is a diagram illustrating the detection unit in the horizontal direction with respect to the coordinate input surface ( It is the figure seen from the side direction.

  In FIG. 3, the detection unit of the sensor unit 1 includes a one-dimensional line CCD 41, lenses 42 and 43 as a condensing optical system, a diaphragm 44 that roughly restricts the incident direction of incident light, and incident of extraneous light such as visible light. An infrared filter 45 is provided to prevent this. In the present embodiment, the light projecting unit and the detection unit are arranged to overlap each other, and the distance L between the light projecting unit and the detection unit is sufficiently larger than the distance from the light projecting unit to the retroreflective member 4. It is set to a small value. Even if it has the distance L between a light projection part and a detection part, it becomes the structure which can detect sufficient retroreflection light from the retroreflection member 4 with a detection part. The broken line part of Fig.3 (a) shows arrangement | positioning of the light projection part of the sensor unit 1 in FIG.3 (b).

  The infrared light emitted from the infrared LED 31 of the light projecting unit and projected by the light projecting lens 32 is reflected by the retroreflective member 4, passes through the infrared filter 45 and the diaphragm 44 of the detection unit, and is a condensing lens. The light is condensed on the detection surface (light receiving surface) of the line CCD 41 by 42 and 43. The diaphragm 44 mainly restricts the visual field in the height direction from the coordinate input surface so as to allow only the retroreflected light of the retroreflective member 4 to pass, and only roughly restricts the visual field in the in-plane direction. It is. The control of the light in the in-plane direction is performed by a method separately described later.

  In further explanation, when the infrared light projected in a range of approximately 90 degrees from the light projecting portion is reflected by the retroreflective member 4 and condensed on the detection surface of the line CCD 41 through the above path, An image is formed on the pixels of the line CCD 41 according to the incident angle of the reflected light. Accordingly, since the line CCD 41 outputs a light amount distribution corresponding to the incident angle of the reflected light as a signal, the pixel number of the line CCD 41 indicates angle information.

<Control / arithmetic unit 2>
Between the control / arithmetic unit 2, the sensor unit 1L, and the sensor unit 1R, a CCD control signal for controlling the operation of the line CCD 41, a clock signal for the line CCD 41, an output signal of the line CCD 41, and an infrared LED 31 are driven. LED drive signals are exchanged.

  FIG. 4 is a block diagram showing a configuration centering on the control / arithmetic unit 2.

  In FIG. 4, the control / arithmetic unit 2 includes A / D converters 81L and 81R, a memory 82, a CPU (arithmetic control circuit) 83, LED drive circuits 84L and 84R, a clock supply circuit 86, a clock generation circuit 87, and a serial interface 88. It has. The A / D converters 81L and 81R and the LED drive circuits 84L and 84R are provided corresponding to the sensor unit 1L and the sensor unit 1R, respectively.

  The CPU 83 is composed of a one-chip microcomputer or the like, and outputs a CCD control signal and an LED drive signal, and based on the control program, FIG. 13, FIG. 14, FIG. 18, FIG. 19, FIG. 21 and the processes shown in the flowcharts of FIGS. 25 and 26 are executed. The CCD control signal is used for shutter timing of the line CCD 41, data output control, and the like. The LED drive signal is supplied from the CPU 83 to the infrared LED 31 of the sensor unit 1 via the LED drive circuits 84L and 84R. The clock generation circuit 87 generates a clock signal. The clock signal is supplied from the clock generation circuit 87 to the sensor units 1L and 1R, and is also supplied to the CPU 83 for performing various controls in synchronization with the line CCD 41.

  The output signal of the line CCD 41 constituting the detection unit of the sensor unit 1 is input to the A / D converters 81L and 81R, and is converted into a digital value by the A / D converters 81L and 81R under the control of the CPU 83. The converted digital value is stored in the memory 82 as necessary, an angle is calculated by an angle calculation method described later, and further, a coordinate value is calculated by a coordinate calculation method described later. The calculation result is output via a serial interface 88 or the like to an external device such as a PC connected to a display device arranged so as to overlap the coordinate input device. The clock supply circuit 86 supplies a clock to the CPU 83 alone.

<Light intensity distribution detection>
FIG. 5 is a timing chart showing CCD control signals and LED drive signals.

  In FIG. 5, reference numerals 91, 92, 93 denote CCD control signals for controlling the line CCD 41 of the left and right sensor units 1L, 1R. The shutter release time of the line CCD 41 is determined at the interval of the CCD control signal 91 (Sh). The CCD control signal 92 (ICGL) and the CCD control signal 93 (ICGR) are gate signals supplied to the left and right sensor units 1L and 1R, respectively, and are signals for transferring the charges of the photoelectric conversion unit in the line CCD 41 to the reading unit. It is.

  Reference numerals 94 and 95 denote driving signals for driving the infrared LEDs 31 of the left and right sensor units 1L and 1R. In order to light the infrared LED 31 of the sensor unit 1L in the first cycle of the CCD control signal 91 (Sh), an LED drive signal 94 (LEDL) is supplied to the infrared LED 31 via the LED drive circuit 84L. In order to turn on the infrared LED 31 of the sensor unit 1R in the next cycle of the CCD control signal 91 (Sh), an LED drive signal 95 (LEDR) is supplied to the infrared LED 31 via the LED drive circuit 84R. After driving the left and right sensor units 1L, 1R of the infrared LEDs 31, the signal of the line CCD 41 is read from the left and right sensor units 1L, 1R.

  FIG. 6A is a diagram showing a light amount distribution as an output of the sensor units 1L and 1R when no instruction is input to the coordinate input effective area 3 with a finger or an indicator, and FIG. 6B is a coordinate input effective. It is a figure which shows the light quantity distribution as an output of sensor unit 1L, 1R at the time of performing instruction input to the area | region 3 with a finger | toe or an indicator.

  In FIG. 6, the horizontal axis corresponds to the pixel number of each CCD pixel, and the vertical axis represents the level of the optical signal output from each CCD pixel. When there is no instruction input by the finger or the pointing tool with respect to the coordinate input effective area 3, that is, when there is no light-shielding portion, as signals read (output) from the line CCDs 41 of the left and right sensor units 1L and 1R, The light quantity distribution shown in FIG. 6A is obtained. Of course, such a light quantity distribution is not necessarily obtained in any system. Retroreflective characteristics depending on the incident angle of the retroreflective member 4, characteristics of the light projecting portion including the infrared LED 31, changes with time (dirt of the reflecting surface, etc.) Therefore, the light quantity distribution changes.

  Assume that A shown in the figure is the output level when the maximum light amount is detected, and B shown in the figure is the lowest output level. Therefore, in a state where there is no retroreflected light, the obtained output level is in the vicinity of B, and as the amount of reflected light from the retroreflective member 4 increases, the output level approaches A. As described above, the signals output from the line CCDs 41 of the left and right sensor units 1L and 1R are sequentially A / D converted by the A / D converters 81L and 81R of the control / arithmetic unit 2, and taken into the CPU 83 as digital data. .

  On the other hand, when an instruction is input to the coordinate input effective area 3 with a finger or an indicator, that is, when the retroreflected light from the retroreflective member 4 is blocked, the data is read from the left and right sensor units 1L and 1R, respectively. As a (output) signal, a light quantity distribution shown in FIG. 6B is obtained. That is, since the retroreflected light corresponding to the portion C shown in the figure is blocked by the finger or the pointing tool, the amount of light is reduced only in the light-shielded portion.

  Detection of the presence / absence of an instruction input by the finger or pointing tool for the coordinate input effective area 3 (presence / absence of shielding of retroreflected light from the retroreflective member 4) is performed by detecting the change in the light amount distribution. More specifically, first, an initial state in which there is no instruction input by a finger or pointing tool for the coordinate input effective area 3 as shown in FIG. 6A (hereinafter, data obtained in the initial state is referred to as initial data). Is stored in advance in the memory 82 of the control / arithmetic unit 2. Next, the CPU 83 calculates whether or not there is a change in the light amount distribution as shown in FIG. 6B by calculating the difference between the data obtained in each sample period and the initial data stored in advance. Determine.

<Angle calculation>
In the angle calculation in which the CPU 83 of the control / arithmetic unit 2 calculates the angle (direction) viewed from the sensor unit 1 at the position designated by the finger or the pointing tool on the coordinate input effective area 3 of the coordinate input device, first, the sensor It is necessary to detect the light shielding range of the light projected from the light projecting unit of the unit 1.

  As described above, since the light amount distribution as the output of the line CCD 41 of the sensor unit 1 is not constant due to changes over time, the above-described initial data is stored when the system incorporating the coordinate input device is started. Is desirable. That is, if initial data is set at the time of shipment of the coordinate input device from the factory and the initial data is not updated sequentially, the following results are caused. For example, if dust adheres to a certain part of the retroreflective surface of the retroreflective member 4, the retroreflective efficiency at the dust adhered part decreases, so that the coordinate input operation is as if the dust adhered part (direction viewed from the sensor unit 1). Cause serious consequences of false positives.

  Therefore, by storing the above-mentioned initial data in the memory 82 of the control / arithmetic unit 2 at the start-up of the system incorporating the coordinate input device, the retroreflective surface of the retroreflective member 4 becomes dust or dust over time. Even if the retroreflective efficiency decreases due to contamination, the state can be reset as the initial state. As a result, it is possible to obtain an excellent advantage that the erroneous detection is not caused.

  Of course, the retroreflected light (optical signal) from the retroreflective member 4 is completely received by the CCD pixel of the sensor unit 1 corresponding to the adhering part of the dust and dust due to the influence of dust and dust adhering to the retroreflective member 4. If it is not possible to do so, it becomes impossible to calculate coordinates, and dust or dust must be removed by some method. If the optical signal from the retroreflective member 4 is greatly reduced, the reliability of the optical signal is reduced due to the S / N ratio (for example, the same point on the coordinate input effective area 3 is indicated) However, it is preferable to remove dust, dust and the like attached to the retroreflective member 4 even in this state. .

  Now, when the coordinate input device is turned on, there is no illumination from the light projecting portion of the sensor unit 1 in the state where there is no instruction input by the finger or the pointing tool to the coordinate input effective area 3 (there is no light shielding portion). The output of the line CCD 41 is A / D converted by the A / D converters 81L and 81R of the control / arithmetic unit 2, and the A / D converted data is stored in the memory 82 as Bas_data [N]. This is data including variations in bias of the line CCD 41 and the like, and is data near the output level of B in FIG. Here, N in the figure is a pixel number, and a pixel number corresponding to an effective input range is used.

  Next, the light amount distribution data output from the line CCD 41 of the sensor unit 1 in a state where illumination is performed from the light projecting unit of the sensor unit 1 is stored in the memory 82 as Ref_data [N]. The light amount distribution data is data indicated by a solid line in FIG. Thereby, the storage of the initial data is completed.

  The CPU 83 of the control / arithmetic unit 2 uses the data (Bas_data [N], Ref_data [N]) stored in the memory 82 to input an instruction to the coordinate input effective area 3 with a finger or an indicator. Whether or not there is a light shielding range is determined. Here, out of the light amount distribution data output from the line CCD 41 of the sensor unit 1, data in a certain sample period is Norm_data [N].

  First, in order to specify the light shielding range by the finger or the pointing tool for the retroreflected light from the retroreflective member 4, the presence or absence of the light shielding range 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 data change. The absolute amount of data change is calculated for each pixel of the line CCD 41 by the following equation (1) 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 of the line CCD 41. Since this comparison process only takes the difference between Norm_data [N] and Ref_data [N] and compares it with the threshold value Vtha, the presence or absence of an instruction input by the finger or the pointing tool to the coordinate input effective area 3 without much processing time. Can be determined at high speed. When the number of pixels exceeding the threshold Vtha for the first time is detected exceeding a predetermined number, it is determined that an instruction input has been made in the coordinate input effective area 3.

  Next, in order to detect a pixel exceeding the threshold value Vtha with higher accuracy, an instruction input point for the coordinate input effective area 3 is determined by calculating a data change ratio. 910 shown in FIG. 7 is a retroreflective surface of the retroreflective member 4. Here, assuming that the reflectance of the α region of the retroreflective surface has decreased due to dirt or the like, the distribution of Ref_data [N] at this time has a smaller amount of reflected light in the α region as shown in FIG. .

  In this state, if the finger or the pointing tool 5 is inserted into the coordinate input effective area 3 as shown in FIG. 7 and substantially half of the retroreflective member 4 is covered, the amount of reflected light is substantially halved. ) Norm_data [N] (distribution indicated by a thick solid line) is observed. When the above formula (1) is applied to this state, the result is as shown in FIG. Here, the vertical axis in FIG. 9A is the differential voltage [mV] from the initial state.

  When the data Norm_data_a [N] is compared with the threshold value Vtha, there is a case where the original input range is deviated (broken line area in FIG. 9A). 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 or the like increases, resulting in a problem that the coordinate calculation performance is degraded.

  Therefore, the amount of light blocked by the finger or 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 the V2 level in the β region). Calculate

Norm_data_r [N] = Norm_data_a [N] / (Bas_data [N]-Ref_data [N]) (2)
FIG. 9B shows the calculation result according to the equation (2), which is represented by the fluctuation ratio (the right side of the equation (2)), and therefore recursively depending on whether dust or the like is attached to the retroreflective member 4. Even when the reflectance of the reflecting member 4 is different, the expression (2) can be handled equally regardless of whether dust or the like is attached. By separately setting a threshold value Vthr for the calculated data Norm_data_r [N], for example, a pixel having a pixel number at the center of both from the rising and falling pixel numbers of Norm_data_r [N] is used as an input pixel. This makes it possible to acquire pixel information with high accuracy.

Incidentally, FIG. 9B is schematically illustrated for convenience of explanation, and the actual detection signal waveform is illustrated in detail in FIG. Now, it is assumed that the rising part of the light shielding region exceeds the threshold value Vthr at the Nr-th pixel and the falling part of the light-shielding region is below the threshold value Vthr at the Nf-th pixel as compared with the threshold value Vthr. At this time, as described above, the pixel number Np of the line CCD 41 to be output is set as the center pixel number of the rising portion and the falling portion.
Np = Nr + (Nf-Nr) / 2 (3)
You may calculate as follows. However, if the calculation is performed as in Expression (3), the pixel interval of the line CCD 41 becomes the resolution of the output pixel number. Therefore, in order to detect the pixel number with higher resolution, the calculation is performed using the output level information of the pixel.

In FIG. 10, the CCD output level of the pixel number Nr is Lr, and the CCD output level of the pixel number Nr-1 is Lr-1. Similarly, the CCD output level of the pixel number Nf is Lf, and the CCD output level of the pixel number Nf-1 is Lf-1. At this time, the pixel numbers to be detected 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)
As a result, a virtual pixel number corresponding to the CCD output level, that is, a pixel number smaller than the pixel number of the line CCD 41 can be acquired. The output virtual center pixel Npv is
Npv = Nrv + (Nfv-Nrv) / 2 (6)
Determined by

  In this way, by calculating the virtual center pixel number from the pixel number of the line CCD 41 and the output level of the pixel, it is possible to detect the pixel number with higher resolution.

<Conversion from CCD pixel number to angle information>
In order to calculate the actual coordinate value of the position indicated by the finger or pointing tool with respect to the coordinate input effective area 3 from the acquired virtual center pixel number (CCD pixel number), the virtual center pixel number (CCD pixel number) is calculated. ) Must be converted into angle information.

  FIG. 11 is a diagram showing the relationship between CCD pixel numbers and angle information.

  In FIG. 11, the vertical axis represents the angle information θ, and the horizontal axis represents the CCD pixel number. The range indicated by the arrow in the figure is the CCD effective pixel range.

Approximate expression of the relationship between CCD pixel number and angle information,
θ = f (N) (7)
And the conversion from the CCD pixel number to the angle information (data conversion) is performed by this approximate expression.

  As for the approximate expression, it may be possible to obtain angle information with higher accuracy by using a higher-order approximate expression due to optical aberration of the lens or the like. What lens group is used for the detection unit of the sensor unit 1 is closely related to the manufacturing cost. When correcting the optical distortion generally generated by lowering the manufacturing cost of the lens group using a higher-order approximate expression, a certain amount of computing power (calculation speed) is required. Both may be set as appropriate in consideration of the coordinate calculation accuracy required for the product.

<Coordinate calculation method>
FIG. 12 is a diagram illustrating points to be detected on the coordinate input effective area 3 by the sensor unit 1L and the sensor unit 1R.

  In FIG. 12, the horizontal direction of the coordinate input effective area 3 is the X axis, the vertical direction is the Y axis, and the center is the origin of the XY coordinates. The sensor units 1L and 1R are arranged symmetrically with respect to the Y axis on the left and right outside the upper side of the coordinate input effective area 3, and the distance between the sensor units 1L and 1R is Ds.

  Further, the line CCD 41 constituting the detection unit of the sensor units 1L and 1R is arranged so that the normal direction of the light receiving surface forms an angle of 45 degrees with the X axis, and the normal direction is 0 degrees (reference direction). It is defined as At this time, the sign of the angle defines the clockwise direction as the “+” direction for the sensor unit 1L arranged on the left side, and the “+” direction for the counterclockwise direction for the sensor unit 1R arranged on the right side. Defined as direction. Furthermore, Po shown in the figure is an intersection position in the normal direction of the line CCD 41 of the sensor units 1L and 1R, and the distance from the origin in the Y-axis direction is defined as Poy.

  At this time, if the angles formed by the normal direction of the light receiving surface of the line CCD 41 of the sensor units 1L and 1R and the direction of the point P to be detected (angles obtained by the sensor units 1L and 1R) are θL and θR, respectively, The coordinates P (x, y) of the pointing input point (point to be detected) P by the finger or pointing tool for the effective input area 3 is

It can calculate by Formula (8) and Formula (9) represented by these.

  13 and 14 are flowcharts showing the coordinate calculation process.

  13 and 14, a series of coordinate calculation processing steps of the coordinate input device will be described in detail. First, when the power of the coordinate input device is turned on by the operator (step S101), the CPU 83 of the control / arithmetic unit 2 of the coordinate input device performs various initialization such as port setting and timer setting (step S102). Next, the CPU 83 reads out and sets the effective pixel range of the line CCD 41, which is a photoelectric conversion element constituting the detection unit of the sensor units 1L and 1R, from the memory 82 (step S103), and unnecessary charge of the line CCD 41 performed at the time of start-up. Preparation for removal is performed (step S104).

  In photoelectric conversion elements such as the line CCD 41, unnecessary charges may be accumulated when not being operated, and if the output data of the line CCD 41 is used as it is as reference data, detection may be impossible or erroneous detection may occur. In order to avoid this, the CPU 83 reads the output data from the line CCD 41 for the number of times set in advance in the above step S103 in the absence of illumination that does not project light from the light projecting units of the sensor units 1L and 1R (step S105). ). Thereby, unnecessary charges accumulated in the line CCD 41 are removed.

  The CPU 83 determines whether or not the output data from the line CCD 41 has been read a set number of times (step S106). If it is determined that the set number of times has been read, the process proceeds to step S107. Next, the CPU 83 fetches the above-described Bas_data [N] as reference data in the absence of illumination that does not project light from the light projecting units of the sensor units 1L and 1R (step S107), and stores it in the memory 82. This is used for subsequent calculations (step S108). Next, the CPU 83 captures the above-described Ref_data [N] as reference data corresponding to the initial light amount distribution in a state where there is illumination that projects light from the light projecting units of the sensor units 1L and 1R (step S109). In the same manner as described above, it is stored in the memory 82 and used for the subsequent calculations (step S110).

  Steps S101 to S110 are the initial setting operation when the power is turned on. Needless to say, this initial setting operation may be performed by the operator's intention using a reset switch or the like. No. After this initial setting operation, the operation shifts to a normal light amount distribution capturing operation.

  First, the CPU 83 takes in a light amount distribution that is an output of the line CCD 41 of the sensor unit 1 (step S111). Next, the CPU 83 calculates a difference value between the captured light amount distribution and Ref_data [N] (step S112), and the presence / absence of a light shielding portion in the coordinate input effective area 3 (coordinate input is performed in the coordinate input effective area 3). Whether or not) (step S113). If it is determined that there is no light-shielding portion in the coordinate input effective area 3, the CPU 83 returns to step S111 and similarly captures the light amount distribution.

  If it is determined that there is a light-shielding portion in the coordinate input effective area 3, the CPU 83 calculates the ratio of data change according to equation (2) (step S114), and based on the threshold for the ratio obtained by the calculation. The rising edge and falling edge of the data are determined, and the pixel number is calculated by Expression (4), Expression (5), and Expression (6) (Step S115). Next, the CPU 83 calculates Tan θ values respectively corresponding to the left and right sensor units 1L and 1R from the pixel number obtained by the calculation using an approximate polynomial (step S116).

  Next, the CPU 83 calculates the x and y coordinates of the instruction input point (point to be detected) by the finger or the pointing tool with respect to the coordinate input effective area 3 based on the calculated Tanθ value according to the equations (8) and (9). The calculated coordinate data is transmitted to an external device such as a PC via the serial interface 88 (step S118). As the serial interface 88, an arbitrary interface such as a serial communication interface such as USB or RS232C may be used.

  After the process of step S118 is completed, the process returns to step S111, and thereafter, the operation from step S111 to step S118 is continued until the operator turns off the power of the coordinate input device or the reset state is set according to the operator's intention. The process will be repeated. If this repetition cycle is set to, for example, about 10 [msec], the coordinate input device transmits the data of the coordinate of the input point indicated by the finger or the pointing tool 5 to the coordinate input effective area 3 to the external device at a cycle of 100 times / second. It becomes possible to output.

<Method for Setting Effective Pixel Range (Pixel Range Used as Effective Region)>
Next, a first effective pixel range setting method will be described (a second effective pixel range setting method will be described later). In the present embodiment, the light transmitting member 8 that protects the retroreflective member 4 is arranged as shown in FIG. 1 in order to improve the appearance and facilitate maintenance. Due to the arrangement of the light transmitting member 8, as described in detail in the section of the problem, reflection occurs on the surface of the light transmitting member 8 due to the relationship of the incident angle of the light projected from the sensor unit 1 to the light transmitting member 8, A virtual image as shown in FIG. 29B appears.

  FIG. 15A is a diagram showing an effective region boundary and reflected light, and FIG. 15B is a diagram showing a real image and a virtual image.

  In FIG. 15, reflected light is observed outside the boundary of the effective area (the effective area of the signal output from the line CCD 41 of the sensor unit 1) as shown in FIG. When an instruction is actually input to the coordinate input effective area 3 with the finger or the pointing tool 5, not only the real image of the finger or the pointing tool 5 appears in the effective area as shown in FIG. It can be seen that a virtual image appears outside the area.

  In such a state, the pixel number of the line CCD 41 of the sensor unit 1 is read from the beginning, and as described above, the coordinate value of the instruction input point by the finger or the pointing tool with respect to the coordinate input effective area 3 is shown in Expression (2). If calculated from the change rate (Norm_data_a [N] / (Bas_data [N]-Ref_data [N])), there is a possibility that a coordinate value between the real image and the virtual image is calculated.

  In order to avoid the possibility of calculating an intermediate coordinate value between the real image and the virtual image, a field stop is provided so as to block the input light from the light projecting unit of the sensor unit 1 so that the virtual image is not observed. A method for preventing the outside of the effective area boundary as shown in FIG. 15A from being observed by performing the adjustment is conceivable. However, in this method, as described in the section of the problem, not only the cost of the parts is increased in design, but also an assembly process such as adjustment is required.

  Therefore, in the present embodiment, the effective area is set by paying attention to the feature of the light amount distribution obtained by the line CCD 41 of the sensor unit 1.

  When the coordinate input device is used while being superimposed on the display device so that the coordinate input effective region 3 substantially coincides with the display region of the display device, the display region (coordinates) where the coordinate input is actually performed by the finger or the pointing tool 5 Actually, a larger effective area is set for the input effective area 3). Each end of the retroreflective member 4 is an effective effective area boundary.

  FIG. 16 is a diagram illustrating a relationship between one sensor unit and an effective area.

  In FIG. 16, the point A illustrated is one end of the effective region, and the point B illustrated is the other end of the effective region.

  FIG. 17A is a diagram showing a light amount distribution in the effective region, and FIG. 17B is a diagram showing a differential value of the light amount distribution.

  In FIG. 17, the horizontal axis corresponds to the pixel number of each CCD pixel, and the vertical axis represents the level of the optical signal output from each CCD pixel. The light quantity distribution in the effective area as shown in FIG. 16 is as shown in FIG. The reflected light from the cover of the coordinate input device is detected outside the point A which is one end of the effective region (the region on the left side from the point A). Point A, which is one end of the effective region, is a boundary with the reflected light from the cover, and is a break between the sides of the retroreflective member 4 as shown in FIG. The point B, which is the other end of the effective area, becomes a break in the side of the retroreflective member 4 as shown in FIG. In addition, the waveform at the point C shown in the figure is also generated at the break of the side of the retroreflective member 4. Thus, a characteristic reflection characteristic is observed at the end of the retroreflective member 4.

  In the present embodiment, characteristic reflection characteristics based on the configuration of the retroreflective member 4 are determined, and an effective area is determined. The characteristic point of the light quantity distribution in the initial state detected by the line CCD 41 of the sensor unit 1 is a point determined by a change in reflection characteristics in the coordinate input effective area 3 due to the arrangement of the retroreflective member 4. As a feature point extraction method, either a method of extracting a feature point from a differential value in the distribution direction of the light amount distribution detected by the line CCD 41 of the sensor unit 1 or a method of extracting a feature point from a difference value in the distribution direction of the light amount distribution. May be used. The feature points will be described later.

  When the light quantity distribution shown in FIG. 17A is differentiated in the distribution direction, it is as shown in FIG. By differentiating the light amount distribution, it is possible to detect a change in reflection characteristics at points A, B, and C, which are the break points of the retroreflective member 4. From the signal obtained by differentiating the light amount distribution, for example, the maximum value point (A ′ point, B ′ point) at each sign (+, −) is determined as the boundary of the effective area, and each corresponds to the maximum value point. The pixel number of the line CCD 41 to be stored is stored in the memory 82 of the control / arithmetic unit 2. When calculating the coordinate value of the pointing input point by the finger or pointing tool with respect to the coordinate input effective area 3, if the pixel range used for the calculation is limited to pixels between these points (A ′ point, B ′ point), No matter how much a virtual image is generated outside the effective area, the calculation result is not affected by the virtual image.

  In actual calculation, since the light amount distribution of the line CCD 41 of the sensor unit 1 is given as an output level in pixel units, a differential value of the light amount distribution in a strict sense cannot be calculated. Instead, for example, by calculating a difference value between the levels of neighboring pixels, a part having a large output level change is determined as the boundary of the effective region based on the difference value.

  In the differentiation (difference) calculation, disturbances such as noise tend to be emphasized, so that the average is obtained by using a filter as appropriate, or by acquiring a light quantity distribution from the line CCD 41 of the sensor unit 1 multiple times. Techniques such as using values are effective.

  18 and 19 are flowcharts showing a first example of the effective area setting process.

  18 and 19, the CPU 83 of the control / arithmetic unit 2 of the coordinate input device starts this processing when the effective area setting processing routine is called (step S201). The CPU 83 first sets the start number NMIN and end number NMAX of the pixels read from the line CCD 41 of the sensor unit 1 as initial settings. Here, the start number NMIN may be determined from which pixel number to start reading for each system in which the coordinate input device is incorporated. If the pixel number to start reading is 0, 0 is set. . The end number NMAX is set to the maximum pixel number that reliably includes the above-described effective area (step S202).

  Next, the CPU 83 removes the influence of unnecessary data by reading a predetermined number of pixels in order to remove the charge accumulated in the line CCD 41 before taking in the light amount distribution as the output from the line CCD 41 of the sensor unit 1. Therefore, the number of preliminary readings is set (step S203). The CPU 83 performs pixel reading until the set number of preliminary readings is reached (YES in step S205) (step S204).

  Next, the CPU 83 sets the start number NMIN of the line CCD 41 (step S206), captures the light amount distribution data when the light projecting portion of the sensor unit 1 is in the illuminated state (ON), and captures the captured light amount distribution data. Data Don (n) associated with the pixel number is stored in the memory 82 (step S207). The CPU 83 reads the process of step S207 and repeats until the pixel number reaches the end number NMAX (step S208).

  Next, the CPU 83 sets the start number NMIN and the end number NMAX as initial values to the start pixel number E_start and end pixel number E_end of the effective area, respectively (step S209), and the minimum value and maximum value of the difference value are set. Dif_min and Dif_max are initialized for storage (step S210). Thereafter, the CPU 83 calculates a difference value from the pixel number N = NMIN + 1 (step S211). The difference value DifDon (n) is the difference between the pixel of interest and the previous pixel. In the original difference value calculation, a value obtained by dividing the difference amount by the distance between two pieces of data is used. However, in the difference value calculation of the present embodiment, the divisor is calculated as 1 (pixel).

  Next, the CPU 83 compares the difference value DifDon (n) obtained by the above calculation with the minimum value Dif_min (step S212). If the difference value DifDon (n) is smaller than the minimum value Dif_min, the CPU 83 replaces the minimum value Dif_min with the difference value Dif_Don (n), and replaces the pixel number n at that time with the start pixel number E_start of the effective area. (Step S213). If the difference value DifDon (n) is greater than the minimum value Dif_min, the CPU 83 compares the difference value DifDon (n) with the maximum value Dif_Max (step S215). If the difference value DifDon (n) is larger than the maximum value Dif_Max, the CPU 83 replaces the maximum value Dif_Max with the difference value Dif_Don (n), and replaces the pixel number n at that time with the end pixel number E_end of the effective area. (Step S216).

  The CPU 83 repeatedly performs the processing from step S211 to step S216 up to the end number NMAX (step S214), and ends this processing when the end number NMAX is reached (step S217).

  By doing so, at the time of step S217, the pixel number at the point A ′ in FIG. 17B is input to the start pixel number E_start, and the end pixel number E_end is set to B in FIG. 17B. 'The pixel number of the point is input.

  In the subsequent processing for coordinate calculation, between the start pixel number E_start and the end pixel number E_end is used for determining whether or not there is an instruction input by the finger or the pointing tool 5 with respect to the coordinate input effective area 3, and for calculating the virtual center pixel. If processing is performed with attention paid only to the pixel data, it is possible to remove the influence of a virtual image or the like.

  In the effective area determination method described above, the effective area is specified using the feature points on both sides of the effective area, but either one of the feature points on both sides is used, or another feature point is used. It may be used. For example, in the case where it is unavoidable to adopt a configuration in which it is difficult to determine point A because the reflected light from the cover in the vicinity of point A in FIG. 17A is large, B in FIG. It is also possible to determine the effective area by detecting only the points.

  Actually, the pixel range (angle range) used as the effective area in the line CCD 41 of the sensor unit 1 is fixed at the design stage. However, the reading start pixel described above varies due to an error such as attachment of the sensor unit 1 to the casing of the coordinate input device.

  Thus, if the pixel number of one feature point is known, the pixel range from the feature point pixel number can be calculated. For example, when the feature point pixel number of point B can be determined by the above difference calculation or the like, the position where the number of pixels corresponding to 90 degrees + α (for example, ENUM) has returned is stored as the end of the other effective area. Can be used for coordinate calculation. Here, the α may be determined from the tolerance of the coordinate input device, such as the retroreflective member 4, the coordinate input effective area 3, and the mounting position of the sensor unit 1, and includes an angular range corresponding to the effective area, What is necessary is just to set to the value which does not cover a useless reflection area.

  20 and 21 are flowcharts showing a second example of the effective area setting process.

  20 and 21, the processing from step S301 to step S311 is the same as the processing from step S201 to step S211 in FIG. 18 and FIG. In this process, only the end pixel number of the effective area is detected (steps S312 and S313). Thereafter, the CPU 83 repeats the processing from step S311 to step S313 until the end number NMAX (step S314). When the end number NMAX is reached, the CPU 83 sets a value obtained by subtracting the number of pixels ENUM in the effective area range from the end pixel number E_end as the effective area start pixel number E_start (step S315), and ends this process (step S316). ).

  The feature point of the light quantity distribution is not limited to the point B in FIG. 17A, but has a characteristic in reflection characteristics such as the point A or the point C. Any point may be used as long as it is known at which angle on the input effective area 3.

  In this case, instead of the process of determining the maximum value and the minimum value of the difference values in the entire region, the effective region range in the signal output from the line CCD 41 of the sensor unit 1 is set in advance. In consideration, the feature point can be determined by calculating the minimum value of the difference value within the pixel number range that the feature point can take. In setting the effective area range at this time, the start pixel is added or subtracted from the location where the feature point is located to the pixel reading start position and the pixel reading end position in the line CCD 41. It is possible to set a number and an end pixel number.

  In the above-described example, a determination method for determining a feature point by using a difference value is used. However, the determination method is not limited to this determination method. A determination method may be used. For example, as shown in FIG. 22, several threshold values may be set for each region (region I, region II) (threshold value 1, threshold value 2), and an effective region may be set using the intersection of the light amount distribution and the threshold value as a feature point. I do not care.

  As described above, by determining the feature point of the light quantity distribution and setting the effective area, it is not necessary to provide a high-cost field stop and make fine adjustments, and it is a special mark that changes the light quantity There is no need to provide such a member, and it becomes possible to eliminate the influence of unnecessary virtual images at low cost.

  The first effective pixel range setting method has been described above. Next, the second effective pixel range setting method will be described. The second effective pixel range setting method performs the operation of detecting the instruction input coordinates with respect to the coordinate input effective area 3 at the position of the pointing tool shown in FIG. This is a method of actually detecting a light-shielding part E by D and a real image, calculating a signal area F, and setting a median value of the signal area F to a limit value of an effective pixel range (a pixel range used as an effective area), for example.

  Compared to the first effective pixel range setting method described above, the second effective pixel range setting method needs to indicate a predetermined position for each of the sensor unit 1L and the sensor unit 1R on the coordinate input effective region 3, Although the amount of work is doubled in terms of increasing the predetermined position, it can be said that it is a disadvantageous method, but an excellent advantage can be obtained from the following viewpoint.

  That is, unless the dimension of the light transmitting member 108a related to the housing opening shown in FIG. 29A and the positional relationship of the sensor unit 101 can be accurately managed (the direction of the light beam I in FIG. 30 means accurate) The first effective pixel range setting method described above may have reduced reliability. Further, even in such a case, it is necessary to sufficiently increase the range of the light beam H and the light beam I in FIG. 30, in other words, to sufficiently increase the black frame portion in order to make sense.

  This causes a large obstacle on the product that the entire coordinate input device becomes larger than the display area (substantially equal to the coordinate input effective area 3) of the display device arranged to overlap the coordinate input device. Needless to say, setting the component tolerances high and accurately managing the positional relationship between the light transmitting member and the sensor unit significantly increases the component cost. Therefore, by configuring the effective pixel range by actually obtaining a signal as shown in FIG. 23, the black frame portion can be made as small as possible and the product can be constructed at low cost, even if a component with a rough component tolerance is used. It becomes possible to do.

  The above setting may be performed not only on the assembly line of the coordinate input device in the factory but also in the market after the shipment of the coordinate input device. That is, even if the case of the coordinate input device is deformed due to an operation environment assumed in the market (for example, temperature or humidity), the CCD pixel can be obtained by the operator indicating a predetermined position of the coordinate input effective area. It is also possible to reset the effective pixel range as necessary to maintain a highly reliable state.

  Furthermore, in a large coordinate input apparatus as shown in FIG. 28, it is conceivable that the housing of the coordinate input apparatus is distorted depending on the installation state. That is, in order to remove the case distortion due to the installation, a certain device configuration is essential, and it is inevitable that the case cost will increase significantly. However, even if there is some distortion, if the other effective pixel range setting method is executed, highly reliable coordinate detection is possible.

  Note that the method of setting the limit value of the effective pixel range includes the following method in addition to the method of setting the median value of the signal region F shown in FIG. That is, there is a method in which the median value is set as the limit value of the effective pixel range from the CCD pixel number on the left side of the light shielding part D by the virtual image and the CCD pixel number on the right side of the light shielding part E by the real image. Further, a value obtained by offsetting a predetermined number of pixels to the CCD pixel number on the left side of the light shielding part E by the real image or a value obtained by offsetting the predetermined number of pixels by the CCD pixel number on the right side of the light shielding part D by the virtual image is the limit of the effective pixel range. There is a method of setting a value (the limit value of the effective pixel range is set to one in the signal region F as a result of offsetting).

  As described above, according to the present embodiment, the feature points of the light quantity distribution in the initial state detected by the line CCDs 41 of the sensor units 1L and 1R of the coordinate input device are extracted, and from the pixel numbers of the feature points, An effective area of a signal output from each line CCD 41 is set. Further, the pointing direction (angle) by the finger or pointing tool with respect to the coordinate input effective area 3 is detected based on the set effective area signal, and the coordinates of the position pointed by the finger or pointing tool are detected based on the detected angle. calculate.

  By setting the effective area as described above, a light transmissive member that protects the retroreflective member 4 without performing fine adjustment by providing a costly field stop for removing the influence of a virtual image as in the prior art. The influence of the virtual image generated by the installation of 8 can be removed, and highly accurate coordinate calculation can be performed. In addition, the installation of the light transmitting member 8 facilitates maintenance, and the black frame portion between the coordinate input effective area 3 and the housing opening can be made as small as possible, and the coordinate input device can be miniaturized.

[Second Embodiment]
The second embodiment of the present invention is different from the first embodiment described above in the effective pixel range setting method in the following points. Since the other elements of the present embodiment are the same as the corresponding ones of the first embodiment (FIGS. 1 to 14) described above, description thereof is omitted.

<Effective pixel range setting method>
FIG. 24A is a diagram showing a light amount distribution when an instruction is not input to the coordinate input effective area 3 with a finger or an indicator, and FIG. 24B is an instruction to the coordinate input effective area 3 with a finger or an indicator. It is a figure which shows light quantity distribution at the time of performing input.

  In FIG. 24, the horizontal axis corresponds to the pixel number of each CCD pixel, and the vertical axis represents the level of the optical signal output from each CCD pixel. The thick solid line waveform is reflected on the surface of the light transmission member 8 due to the incident angle of the light projected from the sensor unit 1 with respect to the light transmission member 8, and a virtual image as shown in FIG. 2 shows an optical signal output from the line CCD 41 of the sensor unit 1 when appears.

  In FIG. 24A, it is assumed that A is the level when the maximum light amount is detected by the detection unit of the sensor unit 1, and B is the lowest level, as in FIG. Therefore, in a state where there is no reflected light, the level obtained is near B, and the level of A is approached as the amount of reflected light increases. FIG. 24B is an example of an output distribution obtained when the pointing tool 5 is arranged at the solid circular position shown in FIG. 29B. An enlarged view of the light shielding region C is shown in FIG. is there.

  In FIG. 23, the light shielding part D is a signal generated by a virtual image of the pointing tool 5 (see FIG. 29B), and the light shielding part E is a real image of the pointing tool 5 (see FIG. 29B). This is a signal to be generated. Further, if the sensor unit 1, the coordinate input effective area 3, and the light transmitting member 8 are in the positional relationship as shown in FIG. 30, at least the light in the area from the light H to the light I has the influence of the virtual image. Since the light beam reflected on the surface of the light transmitting member 108a is not shielded by the pointing tool in the region that is not received (strictly speaking, in a region sufficiently lower than the point F in FIG. 29B (in this case, the direction close to the pointing tool). , The light beam is not affected), and the signal region F is formed. Therefore, the coordinate input device detects two signals of a real image and a virtual image.

  Now, in this type of coordinate input device, assuming that the coordinate input is simultaneously performed with the pointing tool 5 and the finger on the coordinate input effective area 3, two signals are generated by shielding both. When two or more signals are generated, it is determined that the coordinate input is performed by a plurality of instruction means (incorrect operation by the operator) and the detected coordinate value is invalidated (specification), For example, it is assumed that the center coordinates of two or more signals are detected (specification).

  In the case of the former specification, as shown in FIG. 23, a real image signal and a virtual image signal are obtained. As a result, the coordinate input device determines that the operator has made an erroneous operation. Even though only one desired position on the area 3 is indicated, the coordinate input device does not output the coordinate input and does not reflect the operator's intention. On the other hand, in the case of the latter specification, as a result of outputting the centroid (center) position of the virtual image and the real image in response to an instruction to the coordinate input effective area 3 by the operator, that is, coordinates different from the coordinates instructed by the operator. As a result, it is necessary to say that the coordinate input device malfunctions.

  Therefore, as shown in FIG. 23, it is essential to set an area in which the CCD pixel is effective in the signal area F, and to eliminate the influence of the virtual image formed when the light transmitting member 8 is installed on the coordinate input device. It becomes. Therefore, the first and second effective pixel range setting methods of the present embodiment will be described.

In the first effective pixel range setting method of the present embodiment, as described with reference to FIGS. 11 and 12, the intersection point Po in the reference direction (0 degree direction) of the two sensor units 1L and 1R is known, The relationship between the CCD pixel number and the angle is known from equation (7). Now, for ease of explanation, assuming that equation (7) is linear,
θ = A × N + B (10)
A, B: constant, N: detected CCD pixel number, θ: angle.

  If the optical system (sensor unit 1L, 1R) can be installed in the housing of the coordinate input device as a product without angular error, the CCD pixel number obtained at that time can be obtained by providing an indicator at the position Po. Is No, and the detected angle should be θ = 0 from the following equation (11).

θ = A × No + B = 0 (11)
However, there is actually an installation error in assembly, the CCD pixel number obtained by providing the pointing tool at the position Po is N1, and the detected angle does not become θ = 0. Therefore, the detected angle θ is expressed by using the CCD pixel number N1 obtained by providing the indicator at the position Po.
θ = A × (N−N1 + No) + B (12)
It becomes. In other words, if coordinate input is performed by the pointing tool in the reference direction of each of the two sensor units 1L and 1R and Po, which is the intersection position, the coordinate detection error caused by the mounting intersection of the sensor units 1L and 1R is absorbed. can do.

  In other words, if a coordinate input operation is performed at Po, which is a feature point in the coordinate input effective area 3, the reference directions of the two sensor units 1L and 1R can be determined by a single coordinate input operation. This is a superior method. If the reference direction can be accurately obtained in this way, the effective angular range detected by the sensor units 1L and 1R is 45.14 degrees as shown in Expression (12) and FIG. Thus, the effective pixel range of the line CCD 41 can be set accurately as shown in FIG.

  Since the second effective pixel range setting method of the present embodiment is the same as the second effective pixel range setting method of the first embodiment described above, description thereof is omitted.

  25 and 26 are flowcharts showing the effective pixel range setting process.

  First, a pixel effective range setting process is started in the manufacturing process or in response to an instruction from the user (for example, pressing a reset switch) (step S401). The CPU 83 of the control / arithmetic unit 2 of the coordinate input device performs various initializations such as port setting and timer setting (step S402). Next, the CPU 83 reads out and sets the effective pixel range of the line CCD 41, which is a photoelectric conversion element constituting the detection unit of the sensor units 1L and 1R, from the memory 82 (step S403), and unnecessary charges of the line CCD 41 performed at the start-up. Prepare for removal.

  In photoelectric conversion elements such as the line CCD 41, unnecessary charges may be accumulated when not being operated, and if the output data of the line CCD 41 is used as it is as reference data, detection may be impossible or erroneous detection may occur. In order to avoid this, the CPU 83 reads the output data from the line CCD 41 the number of times set in advance in step S403 in the absence of illumination that does not project light from the light projecting units of the sensor units 1L and 1R (step S404). ).

  The CPU 83 determines whether or not the output data from the line CCD 41 has been read a set number of times (step S405). If it is determined that the set number of times has been read, the process proceeds to step S406. Next, the CPU 83 fetches the above-described Bas_data [N] as reference data in the absence of illumination that does not project light from the light projecting units of the sensor units 1L and 1R (step S406), and stores it in the memory 82. This is used for the subsequent calculations (step S407). Next, the CPU 83 captures the above-described Ref_data [N] as reference data corresponding to the initial light amount distribution in a state where there is illumination that projects light from the light projecting units of the sensor units 1L and 1R (step S408). In the same manner as described above, it is stored in the memory 82 and used for the subsequent calculations (step S409).

  Steps S401 to S409 are the initial setting operation of the effective pixel range setting process.

  Next, the CPU 83 increments the counter n (n: integer) (step S410), and in response to an instruction input by a finger or an indicator for a predetermined position (reference point) on the coordinate input effective area 3, the sensor units 1L, 1R The light amount distribution corresponding to the predetermined position is taken in from the line CCD 41 (step S411), and the light amount distribution data is stored in the memory 82 (step S412). Here, the predetermined position is set by a method (Po in FIG. 12) of setting the direction of the angular range detected by the line CCD 41 of the sensor units 1L and 1R and the intersection of the central values. Either of the methods may be used for setting the direction to the outermost corner position.

  Next, the CPU 83 compares the preset nmax value with the value of the counter n (step S413). If the value of the counter n is equal to or less than nmax, the CPU 83 receives the value on the coordinate input effective area 3 from the sensor units 1L and 1R. A light quantity distribution corresponding to the next predetermined position is acquired (step S411) and stored in the memory 82 in the same manner as described above (step S412). Here, in the first effective pixel range setting method described above, nmax = 1, and in the second effective pixel range setting method, nmax = 2.

  Next, the CPU 83 determines the line CCD 41 related to the light shielding position from the light shielding information accompanying the instruction input by the finger or the pointing tool 5 with respect to the predetermined reference point on the coordinate input effective area 3 stored in the memory 82 by the method described above. The pixel number (feature point) is calculated, and the effective pixel range of the CCD pixel (the effective area of the signal output from the line CCD 41) is calculated (step S414). Next, the CPU 83 stores the calculated effective pixel range in the memory 82 (step S415), and ends this processing (step S416). The effective pixel range information stored in the memory 82 is called up in step S103 of FIG. 13 and used for subsequent coordinate calculation.

  In the above processing, a function (for converting an output result of the line CCD 41 of the sensor unit 1 and an output result (CCD pixel number) of the line CCD 41 obtained by an instruction input to the predetermined position in the coordinate input effective area 3 into an angle ( Based on the above equation (7), the effective area of the signal output from the line CCD 41 is set.

  As described above, according to the present embodiment, the amount of light by each line CCD 41 of the sensor units 1L and 1R obtained by indicating a predetermined position of the coordinate input effective area 3 of the coordinate input device with a finger or an indicator. The effective area of the signal output from the detection unit is set from the distribution detection result. Further, the pointing direction (angle) by the finger or the pointing tool is detected based on the set effective area signal, and the coordinates of the predetermined position indicated by the finger or the pointing tool are calculated based on the detected angle.

  By setting the effective area as described above, a light transmissive member that protects the retroreflective member 4 without performing fine adjustment by providing a costly field stop for removing the influence of a virtual image as in the prior art. The influence of the virtual image generated by the installation of 8 can be removed, and highly accurate coordinate calculation can be performed. In addition, the installation of the light transmitting member 8 facilitates maintenance, and the black frame portion between the coordinate input effective area 3 and the housing opening can be made as small as possible, and the coordinate input device can be miniaturized.

  Furthermore, when the predetermined position is set in the direction of the median value of the angle range detected by each line CCD 41 of the sensor units 1L and 1R and at the intersection of the median values of the detection units, 1 for the coordinate input effective area 3 is set. The effective pixel range of each line CCD 41 can be set at least by inputting the coordinates once, and the effective pixel range of each line CCD 41 can be easily set.

  Furthermore, when the predetermined position is set in a direction that is the outermost angle position of the angle range detected by each line CCD 41 of the sensor unit 1L, 1R, when a large coordinate input device shipped from the factory to the market is installed It is possible to easily avoid problems caused by the distortion of the casing in the market of the installation destination.

[Other embodiments]
In the first and second embodiments, the coordinate input device is provided with the control / arithmetic unit 2. However, the present invention is not limited to this, and the coordinate input device can communicate with an external device such as a PC. It is also possible to adopt a configuration in which a part of the function of the control / arithmetic unit 2 is given to the external device while being connected.

  In the present invention, a software program (the flowcharts in FIGS. 13, 14, 18, 19, 20, 21, 25, and 26) that realizes the functions of the above-described embodiments is supplied to a computer or CPU. This can be achieved by the computer or CPU reading and executing the supplied program.

  In this case, the program is directly supplied from a storage medium storing the program, or downloaded from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like. Supplied.

  The form of the program may be in the form of object code, program code executed by an interpreter, script data supplied to an OS (operating system), and the like.

  The present invention also supplies a computer or CPU with a storage medium storing a software program that implements the functions of the above-described embodiments, and the computer or CPU reads and executes the program stored in the storage medium. Can also be achieved.

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

  As a storage medium for storing the program code, for example, ROM, RAM, NV-RAM, floppy (registered trademark) disk, hard disk, optical disk (registered trademark), magneto-optical disk, CD-ROM, MO, CD-R, CD -RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, etc.

  The function of the above-described embodiment is not only by executing the program code read from the computer, but the OS or the like running on the computer performs part or all of the actual processing based on the instruction of the program code. Can also be realized.

It is a block diagram which shows schematic structure of the coordinate input device which concerns on the 1st Embodiment of this invention. (A) is the figure which looked at the light projection part of the sensor unit from the orthogonal | vertical direction with respect to the coordinate input surface, (b) is the figure which looked at the light projection part from the horizontal direction with respect to the coordinate input surface. (A) is the figure which looked at the detection part of the sensor unit from the perpendicular | vertical direction with respect to the coordinate input surface, (b) is the figure which looked at the detection part from the horizontal direction with respect to the coordinate input surface. It is a block diagram which shows the structure centering on a control / arithmetic unit. It is a timing chart which shows a CCD control signal and a LED drive signal. (A) is a figure which shows light quantity distribution as an output of a sensor unit when not performing an instruction input with a finger or an indicator in the coordinate input effective area, and (b) is an instruction input with a finger or an indicator in the coordinate input effective area. It is a figure which shows the light quantity distribution as an output of the sensor unit at the time of performing. It is a figure which shows the state which shielded some retroreflective members with the indicator. (A) is a figure which shows the change of the amount of reflected light when instruction input is not performed with the finger or the pointing tool in the coordinate input effective area, and (b) is the case where the instruction input is performed with the finger or the pointing tool in the coordinate input effective area. It is a figure which shows the change of reflected light quantity. (A) is a diagram showing the relationship between the reflected light amount change amount and the reflected light amount change rate when the equation (1) is applied, and (b) is the reflected light amount change amount and the reflected light amount change rate when the equation (2) is applied. It is a figure which shows the relationship. It is a figure which shows the light-shielding range detection signal. It is a figure which shows the relationship between CCD pixel number and angle information. It is a figure which shows the point which should be detected on the coordinate input effective area | region by a sensor unit. It is a flowchart which shows a coordinate calculation process. It is a continuation of the flowchart of FIG. (A) is a figure which shows an effective area | region boundary and reflected light, (b) is a figure which shows a real image and a virtual image. It is a figure which shows the relationship between one sensor unit and an effective area | region. (A) is a figure which shows light quantity distribution in an effective area | region, (b) is a figure which shows the differential value of light quantity distribution. It is a flowchart which shows the 1st example of an effective area | region setting process. It is a continuation of the flowchart of FIG. It is a flowchart which shows the 2nd example of an effective area | region setting process. It is a continuation of the flowchart of FIG. It is a figure which shows the detection method of a feature point. It is a figure which shows an effective pixel range. (A) is a figure which shows the light quantity distribution when not performing an instruction input with the finger or the pointing tool in the coordinate input effective area, and (b) is the light quantity distribution when the instruction input is performed with the finger or the pointing tool in the coordinate input effective area. FIG. It is a flowchart which shows an effective pixel range setting process. It is a continuation of the flowchart of FIG. It is a block diagram which shows schematic structure of the coordinate input device which concerns on a prior art example. (A) is a figure which shows the state which made the coordinate input effective area | region of a coordinate input device, and the display area of a display apparatus substantially correspond, (b) is the figure which expanded the area | region A part of (a). (A) is the figure which expanded the area | region B part of Fig.28 (a), (b) is the figure which expanded the area | region C part of Fig.28 (a). It is a figure which shows the coordinate input effective area | region corner of the area | region C part of Fig.28 (a).

Explanation of symbols

1L, 1R sensor unit (corresponding to detection means)
2 Control / arithmetic unit 3 Coordinate input effective area 4 Retroreflective member 8 Light transmitting member 83 CPU (corresponding to extraction means, setting means, calculation means)

Claims (5)

A coordinate input effective area, a retroreflective member disposed outside the coordinate input effective area, a protective member disposed between the retroreflective member and the coordinate input effective area, and a surface of the coordinate input effective area Coordinates comprising projection means for projecting light over the entire direction , and detection means for detecting light retroreflected by the retroreflective member and detecting the retroreflected light by a photoelectric conversion element. An input device,
Extraction means for extracting the reflection characteristic of the end portion of the retroreflective member in the light quantity distribution in the initial state detected by the detection means as a feature point;
Setting means for setting an effective area of a signal output by the detection means from a pixel number of the photoelectric conversion element corresponding to the feature point extracted by the extraction means;
And based on the signal of the set effective area to detect the angle from the detecting means of the indication position relative to the coordinate input effective region by the setting unit, coordinates of the designated position relative to the coordinate input effective region based on the said angle coordinate input device characterized by comprising a calculating means for calculating a. Said extraction means, said based on the differential value or the difference value in the distribution direction of the detected light amount distribution by the detecting means and extracting a characteristic point according to claim 1 coordinate input device according. Further comprising a display device,
The coordinate input device according to claim 1, wherein the coordinate input effective region is arranged to overlap the display device so as to substantially coincide with the display region of the display device. A coordinate input effective area, a retroreflective member disposed outside the coordinate input effective area, a protective member disposed between the retroreflective member and the coordinate input effective area, and a surface of the coordinate input effective area Coordinates comprising projection means for projecting light over the entire direction , and detection means for detecting light retroreflected by the retroreflective member and detecting the retroreflected light by a photoelectric conversion element. An input device control method comprising:
Extract the reflection characteristic of the end portion of the retroreflective material in the light amount distribution of the initial state detected by the detecting means as a characteristic point,
From the pixel number of the photoelectric conversion element corresponding to the extracted feature point, set the effective area of the signal output by the detection means,
Said based on the signal of the set effective area to detect the angle from the detecting means of the indication position relative to the coordinate input effective region, calculates the coordinates of the designated position relative to the coordinate input effective region based on the said angle A control method for a coordinate input device . A coordinate input effective area, a retroreflective member disposed outside the coordinate input effective area, a protective member disposed between the retroreflective member and the coordinate input effective area, and a surface of the coordinate input effective area Coordinate input comprising projection means for projecting light over the entire direction, and detection means for detecting light retroreflected by the retroreflective member and detecting the retroreflected light by a photoelectric conversion element. A program for causing a computer to execute an apparatus control method,
The control method is:
An extraction step of extracting, as a feature point, the reflection characteristic of the end of the retroreflective member in the light amount distribution in the initial state detected by the detection means;
From the pixel number of the photoelectric conversion element corresponding to the feature point extracted by the extraction step, a setting step of setting an effective area of the signal output by the detection unit;
The set based on the signal of the set effective region in step detects the angle from the detecting means of the indication position relative to the coordinate input effective region, coordinates of the designated position relative to the coordinate input effective region based on the said angle Ru and a calculation step of calculating a.

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