JP2006235710A - Coordinate input device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To configure a highly reliable coordinate input device which is improved in operability by solving the problem that any change caused between the state of disturbing rays of light at the time of storing the background signal of an optical system coordinate input device by power supply or an SW operation or the like and the state of disturbance light at the time of actually detecting coordinates leads to the factor of any coordinate calculation error. <P>SOLUTION: The pointed position of a pointer is calculated from a difference value between a CCD pixel signal waveform at the time of calculating coordinates and a CCD pixel signal waveform detected right before calculating coordinates. Thus, it is possible to improve operability by eliminating the SW operation of an operator to be performed for setting a background signal, and to remove any influence of disturbance light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, as this type of device, various types of touch panels have been proposed or commercialized, and it is easy to operate a PC on the screen without using special equipment. It is used.

  There are various methods such as a method using a resistance film and a method using ultrasonic waves, but as a method using light, as shown in Patent Document 1 and the like, it is located outside the coordinate input surface. In a configuration in which a retroreflective sheet is provided, the light from the means for illuminating the light is reflected by the retroreflective sheet, and the light quantity distribution is detected by the light receiving means, the angle of the area shielded by a finger or the like in the input area is determined. It is known to detect and determine the coordinates of the shielding position, that is, the input position.

In this optical apparatus, it is desirable that only the light from the above-mentioned light illuminating means is detected by the light receiving means. However, in actuality, the light receiving means detects various lights such as sunlight and illumination light depending on the installation location of the apparatus in addition to the light from the means for illuminating the light. It causes obstacles such as false detection. As conventional techniques related to solving this problem, Patent Literature 2, Patent Literature 3, and Patent Literature 4 describe the contents of a coordinate input device from which the influence of disturbance light is removed.
US Patent No. USP 4507557 JP 2002-108554 A JP 2000-105671 A JP 2000-132340 A

  As described above, if the apparatus is configured without considering the influence of disturbance light such as sunlight or illumination light, there is a problem that the coordinate calculation accuracy is greatly affected.

  This is because the light amount distribution detected by the light receiving means is changed by disturbance light even when there is no input of a pointing tool or a finger. That is, the light is illuminated to detect a desired light amount distribution, and the shielding position is detected. However, even when this illumination is not lit, there is disturbance light. It will be included. Normally, in order to cancel out the disturbance light, the data when the lighting is not turned on is stored in the memory. The disturbance light included in the data is canceled, and the input position coordinates are calculated.

  In order to solve this problem, Patent Document 2 describes that the difference between signals when the light projecting means is turned on and when it is not lighted is detected continuously (every sampling) to remove the influence of ambient light. Yes.

  However, this type of coordinate input device is overwhelmingly often integrated with a computer display device, and drawing speed is one of the important items for evaluating performance. That is, it is important that the operator can input without stress, and it is essential that the drawing speed follows the input speed of the operator without delay.

  However, in Patent Document 2, the coordinate output speed as described above is satisfied in order to acquire and store the data when the lighting is turned on and off every time the coordinate calculation (coordinate output) sampling is performed. It is difficult.

  In addition, in order to obtain a coordinate input device having a large display and a high resolution and sufficient resolution for the pixels of the display, it is essential to increase the resolution of the light receiving means, and the light quantity distribution detected by this light receiving means It is desirable to minimize access to a memory for storing data.

  On the other hand, Patent Document 3 and Patent Document 4 store an image of an input area captured in advance as a reference image, and then extract a difference between the image of the input area captured by each image sensor and the reference image, thereby providing disturbance. Although a configuration that eliminates the influence of light and unnecessary light is disclosed, the reference image information of the input area captured in advance and the image information that is actually detected during use of the device change depending on, for example, disturbance light / unnecessary light In such a case, the influence could not be removed, and there was a risk of greatly degrading accuracy. If the above-mentioned disturbance light / unnecessary light changes during use and the accuracy is greatly deteriorated, if the operator determines that and updates the reference image, the disturbance light / unnecessary light Although the influence can be removed, the operation must be performed during the conference while the device is in use, for example, and if the interruption of the conference progress is taken into consideration, the device has never been excellent in operability.

  In order to solve the above problems, the present invention is provided with at least two light receiving detection means at the corners of the coordinate input effective area, and a finger or an indicator indicates the change in the light quantity distribution detected by the light receiving means. An optical coordinate input device that has an angle detection means for detecting a direction and calculates position coordinates indicated by the finger or pointing tool based on a plurality of derived angle information, and is sampled for calculating position coordinates. By having an angle detection means for detecting the direction indicated by a finger or an indicator from the difference information between the output result of the detected detection means and the output result of the detection means sampled immediately before the sampling, disturbance light is provided. The coordinate calculation can be performed with high accuracy by eliminating the influence of the above.

  Specifically, in order to sample the position coordinates of the finger or the pointing tool, a reference data storage unit that stores, as reference data, an output result of the detection unit at the Nth light projection by the light projecting unit, and a sampling By calculating the output result and the difference value of the detection means at the time of the N + 1th light projection, disturbance light that reduces the coordinate calculation accuracy equivalent to the Nth sampling time and the N + 1th sampling time is included. Therefore, the influence of disturbance light can be eliminated, and the angle detection by the angle detection means can be performed with high accuracy.

  Furthermore, since the output result of the detection means at the time of the N + 1th sampling is updated as reference data and stored again in the reference data storage means, the coordinate input device can be used for a long time. Even if the degree of influence of disturbance light assumed in use changes, the position can always be detected with high accuracy.

  Further, the storage means for storing the output result of the detection means when the light projection by the light projection means is not lit, the output result of the detection means when the light projection is performed by the light projection means, or the difference information between the two. However, the information should be updated only when the power is turned on for the first time when it is used for a long time or only when it is shipped from the factory. Thus, an unnecessary operation of the operator that removes the influence of the disturbance can be eliminated.

  As described above, in the present invention, in order to sample the position coordinates of the finger or the pointing tool, the reference data storage for storing, as reference data, the output result of the detection means at the Nth light projection by the light projecting means. The angle detection by the angle detection means can be performed with high accuracy by calculating the output value and the difference value of the means and the detection means at the time of N + 1 sampling times. In other words, at the sampling number N and the sampling number N + 1, the coordinate calculation accuracy is reduced at the time interval (corresponding to 0.01 second in a coordinate input device capable of sampling at 100 times / second). Since the disturbance light that causes the reduction is included equally, the influence of the disturbance light can be eliminated by generating a difference signal between the two, and as a result, an excellent effect that enables highly accurate coordinate calculation can be obtained. Become.

  Furthermore, it has a reference data update means for updating the output result of the detection means at the time of the N + 1th light projection as the update data of the stored reference data and updating / storing it in the reference data storage means. Therefore, even if the degree of influence of disturbance light assumed when the coordinate input device is used for a long time changes, position detection can always be performed with high accuracy. Further, the storage means for storing the output result of the detection means when the light projection by the light projection means is not lit, the output result of the detection means when the light projection is performed by the light projection means, or the difference information between the two. If it has, the information should be updated only when the power is turned on for the first time when using it for a long time or only when it is shipped from the factory. For example, it is possible to realize a coordinate input device that is highly reliable and excellent in operability by eliminating an unnecessary operation of the operator that requires the operator to perform a reset operation to remove the influence of disturbance.

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

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

  In the figure, reference numerals 1L and 1R denote sensor units 1 each having a light projecting means and a detecting means. In the case of this embodiment, as shown in the figure, the predetermined positions are parallel to the X axis and symmetrical to the Y axis. It is arranged at a distance. The sensor unit 1 is connected to the control / arithmetic unit 2, receives a control signal from the control / arithmetic unit 2, and transmits the detected signal to the control / arithmetic unit 2. Reference numeral 4 denotes retroreflective means having a retroreflective surface that reflects incident light in the direction of arrival, and retroreflects light projected from the left and right sensor units 1 in a range of approximately 90 ° toward the sensor unit 1.

  The light retroreflected by the retroreflective member 4 is detected one-dimensionally by the detection means of the sensor unit 1 constituted by a condensing optical system and a line CCD, and the light quantity distribution is sent to the control / arithmetic unit. It is done.

  The coordinate input effective area 3 described above can be used as an interactive input device by being configured by a display screen of a display device such as a PDP, a rear projector, or an LCD panel.

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

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

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

<Detailed description of sensor unit 1>
FIG. 4 shows a configuration example of the light projecting means in the sensor unit 1.

  FIG. 4A is a diagram of the light projecting unit viewed from the front direction (perpendicular to the coordinate input surface). In FIG. 4, reference numeral 31 denotes an infrared LED that emits infrared light. To project light in a range of approximately 90 °. On the other hand, FIG. 4-2 is a side view of the same configuration seen from the side (horizontal direction with respect to the input surface). In this direction, light from the infrared LED 31 is projected as a light beam restricted in the vertical direction, Mainly, the retroreflective member 4 is configured to emit light.

  FIG. 5 shows the detecting means in the sensor unit 1. Like FIG. 4, FIG. 5-1 shows the front direction (perpendicular to the coordinate input surface), and FIG. It is a side view. The broken line portion in the front view 5-1 shows the arrangement of the light projecting means in the sensor unit 1 described above shown in the side view 5-2. In the case of the present embodiment, the light projecting means and the detection means are arranged so that the distance L is sufficiently smaller than the distance from the light projecting means to the retroreflective means 4, and the distance L is present. Even if it does, it becomes the structure which can detect sufficient retroreflection light with a detection means.

  In FIG. 5B, the detection means of the present invention includes a one-dimensional line CCD 41, lenses 42 and 43 as a condensing optical system, an aperture 44 that roughly restricts the incident direction of incident light, and extra light such as visible light. The light projected by the light projecting means is reflected by the retroreflective member 4, passes through the infrared filter 45 and the diaphragm 44, and is collected by the condensing lenses 42 and 43. The light is collected on the CCD detection surface.

  Further explaining in FIG. 5A, the light of the light projecting means projected in the substantially 90 ° direction described above is reflected by the retroreflective member 4 and is condensed through the infrared filter 45 and the aperture 44. The lenses 42 and 43 form an image on the pixel of the CCD 41 corresponding to the incident angle of the reflected light. Accordingly, since the output signal of the CCD 41 outputs a light amount distribution corresponding to the incident angle of the reflected light, the CCD 41 pixel number indicates angle information.

<Description of control / arithmetic unit>
A CCD control signal, a CCD clock signal, a CCD output signal, and an LED drive signal are exchanged between the control / arithmetic unit 2 of FIG. 3 and the sensor unit 1L and sensor unit 1R.

  FIG. 6 is a block diagram of the control / arithmetic unit. The CCD control signal is output from an arithmetic control circuit 83 constituted by a one-chip microcomputer or the like, and performs CCD shutter timing, data output control, and the like. The CCD clock is sent from the clock generation circuit 87 to the sensor unit, and is also input to the arithmetic control circuit 83 in order to perform various controls in synchronization with the CCD.

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

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

<Explanation of light intensity distribution detection>
FIG. 7 is a timing chart of control signals.

  Reference numerals 91, 92, and 93 denote control signals for CCD control, and the shutter release time of the CCD is determined by the interval of 91SH signals. Reference numerals 92 and 93 denote gate signals to the left and right sensors, respectively, which are signals for transferring the charge of the photoelectric conversion unit in the CCD to the reading unit.

  Reference numerals 94 and 95 denote left and right LED drive signals. In order to light one LED (the LED in the sensor unit 1L) in the first cycle of SH, the 94 drive signal is an LED drive circuit (in this case, LED drive circuit 84L). ) To be supplied to the LED. In the next cycle, the other LED (in this case, the LED in the sensor unit 1R) is driven. After the driving of both LEDs is completed, the CCD signal is read from the left and right sensors.

  Next, a CCD signal to be read will be described. However, in order to facilitate understanding, it is assumed here that there is no disturbance light (unnecessary light) such as sunlight, that is, there is no temporal change in initial data described later. explain.

  FIG. 8-1 is a signal when no light signal is detected when light projection by the light projecting unit is not performed. FIG. 8-1 does not include coordinate input by a finger or an indicator, for example. FIG. 6 is a diagram schematically showing CCD signals obtained when light is projected by a light projecting unit in a case (when there is no light shielding portion). The output signal of FIG. 8-2 includes the characteristics of the retroreflective sheet 4 (the retroreflective efficiency depending on the incident angle of the retroreflective member 4 described above), the characteristics of the light projecting means including the LED, the size of the coordinate input effective area, Shape (because the incident angle at which the light beam from the light projecting means enters the retroreflective member varies depending on the size and shape, and the light beam distance from the light projecting means to the retroreflective member varies greatly) This distribution changes due to changes (such as dirt on the reflective surface). Therefore, it is practically difficult to configure the output level of each CCD pixel to be constant at the level A value shown in FIG. 8-2, for example, as shown in FIG. In general, non-uniform signals are output.

  Accordingly, in FIGS. 8A and 8B, if the level A is the level at which the maximum light amount is detected, and the level B is the minimum level, there is no reflected light from the retroreflective member. In the state, the level obtained is near B (because the explanation here assumes that unnecessary light such as disturbance does not exist as described above), and approaches the level A as the amount of reflected light increases. . In this way, the data output from the CCD is sequentially AD converted and taken into the CPU as digital data.

  Fig. 8-3 shows an example of output when input is performed with a finger or the like, that is, when reflected light is blocked. Since the reflected light is blocked by the finger or the like at C, the amount of light is reduced only at that part. The detection is performed by detecting the change in the light quantity distribution. Specifically, first, as shown in FIGS. 8A and 8B, the initial state where the coordinate input is not performed (hereinafter referred to as “the coordinate input”). , The data obtained in the initial state is referred to as initial data) in advance in the memory 82, and by calculating the difference between the data obtained in each sample period and the initial data stored in advance, Determine whether there is a change as shown in Figure 8-3.

<Description of angle calculation>
When the power is turned on, in the state of no input (no light blocking part), the CCD output is first AD converted without illuminating from the light projecting means, and this is converted to Bas_data [N] (corresponding to Fig. 8-1). Signal) is stored in the memory 82. This is data including variations in the bias of the CCD 41 and the like, and is data near the level B in FIG. 8-1 (here, it is described that unnecessary light is not detected as described above). Here, N is a pixel number, and a pixel number corresponding to an effective input range is used. Next, the light amount distribution in the state illuminated from the light projecting means is stored (signal equivalent to FIG. 8-2), and is set as Ref_data [N], and the initial data storage is completed.

  Assuming that the data of a certain sample period is Norm_data [N], the distribution of Norm_data [N] output by the CCD is not uniform as shown in FIG. 8-2. If the process proceeds at an absolute level, it is difficult to calculate an accurate light shielding position. Therefore, as shown by the following equation, the change ratio is calculated to determine the input position with higher accuracy.

Norm_data_r [N] =
(Norm_data_ [N] −Bas_data [N]) / (Ref_data [N] −Bas_data [N]) (2)
This calculation result is as shown in FIG. 8-4 and is represented by a fluctuation ratio. For example, a threshold value Vthr is set, and the pixel number of the rising portion and the falling portion is set as the input pixel, for example. As a result, pixel information can be acquired with high accuracy. Of course, it goes without saying that the presence / absence of input determination according to the equation (1) described above may be performed using the newly set threshold value Vthr.

By the way, FIG. 8-4 is schematically drawn for explanation, and an actual detection signal waveform is as shown in FIG. 9 when the light-shielding portion is displayed in detail. Now, it is assumed that the falling portion of the light shielding region as compared with the threshold value Vthr exceeds the threshold value Vthr in the Nf-th pixel, assuming that the Nr-th pixel exceeds the threshold value Vthr. At this time, as described above, the CCD pixel number Np of the CCD to be output is set as the median value of the pixel numbers of the rising and falling portions.
Np = Nr + (Nf-Nr) / 2 (3)
In this case, the CCD pixel interval becomes the resolution of the output pixel number. Therefore, in order to detect with higher resolution, calculation is performed using the output level information of the pixel.

In FIG. 9, the CCD output level of pixel number Nr is Lr and the output level of pixel number Nr−1 is Lr−1. Similarly, the output level of the pixel number Nf is Lf, and the output level of the pixel number Nf−1 is Lf−1. If the pixel numbers to be detected at this time are Nrv and Nfv respectively,
Nrv = Nr-1 + (Vthr-Lr) / (Lr-1-Lr) (4)
Nfv = Nf-1 + (Vthr-Lf-1) / (Lf-Lf-1) (5)
Is calculated, a virtual pixel number corresponding to the output level, that is, a pixel number smaller than the CCD pixel number can be obtained, and the output virtual center pixel Npv is
Npv = Nrv + (Nfv-Nrv) / 2 (6)
Determined by

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

<Explanation of the influence of disturbance and its removal>
In the above description, no consideration is given to the influence of disturbance light (unnecessary light) such as sunlight. Therefore, here, the influence of unnecessary light and a configuration for removing the influence will be described.

  If the initial data (equivalent to Base_data [N] and Ref_data [N]) is set at the time of shipment from the factory, it can be set in an inspection room where there is no ambient light. It is possible to get initial data without. However, in the environment where the product is actually installed under the user in the market, lighting equipment such as a fluorescent lamp and a heating bulb will be present above the product, and in a conference room with a window, It is also assumed that sunlight directly hits the sensor unit to detect sunlight. In order to mitigate the influence of this unnecessary light, the above-described infrared filter 45 is provided in each sensor unit, but it is impossible to completely remove this unnecessary light. It must be assumed that some unnecessary light is detected.

  Furthermore, assuming that dust is attached to a predetermined position of the retroreflective member 4 during actual use, for example, the retroreflective efficiency at that portion decreases, so that the direction as seen from the sensor It may be erroneously detected that a light-shielding part is formed by the coordinate input operation, resulting in a serious failure.

  In other words, in the specification where the initial data is the base_data [N] when the light projection by the light projecting means is non-light-projected and the Ref_data [N] at the time of light projection by the light projecting means is set at the time of factory shipment Depending on the environment where the user actually installs or changes over time, the data obtained by the light projecting means in that environment and the data at the time of non-projection will be different from the initial data set, and shipped from the factory. When initial data is sometimes set and the calculation is executed as described above, the deterioration of the coordinate calculation performance becomes significant.

  Therefore, if the specifications are such that the above-mentioned initial data is updated / stored when the operator starts up the system, unnecessary light changes during use, or dust adheres during use, resulting in significant reflection efficiency. If there is no change, the deterioration of coordinate calculation accuracy or malfunction can be eliminated even if the optical characteristics change due to the installation environment or aging of the apparatus.

  However, when the system is activated and used for a long time (when initial data is not updated for a long time), the following may be a concern. If a device incorporating the optical coordinate input device of the present invention is installed in a conference room having a window, the conference room will be illuminated by sunlight during the day, and at night the conference will be performed by a fluorescent lamp or the like. It keeps the brightness of the room. Focusing on this light source change, for example, the system is set up to hold a meeting from noon, and Bas_data [N] is obtained as shown in Fig. 10-1 when light projection by the light projecting means is non-light projection. For example, although the output data is data near the B level, the influence of sunlight is detected, and the result is different from the state shown in FIG. It becomes. In this state, if the data Ref_data [N] at the time of light projection by the light projecting means is acquired, only the output signal that is not affected by sunlight in Fig. 8-1 and the effect of sunlight in Fig. 10-1 are detected. A signal as shown in FIG. 10-2 is obtained as a signal obtained by superimposing these signals. If the degree of the influence of sunlight is constant (the output distribution in FIG. 10-1 does not change), the light-shielding part by the finger or the pointing tool can be accurately calculated by the method described above. However, as the conference proceeded, the sun was hidden behind the clouds and the conference room became dim, or the conference continued continuously until evening and the outside was dark and the fluorescent lights were lit (here In the description of, it is assumed that unnecessary light from the fluorescent lamp is not detected at all), the influence of sunlight is completely eliminated. At that time, the signal obtained by the CCD sensor is, for example, as shown in FIG. 10-3 in a state where light shielding by a finger or an indicator is not generated (a state in which coordinate input is not performed) (the influence of sunlight). Since unnecessary light is not detected at all, it is equivalent to the output signal in Fig. 8-2). When the fluctuation ratio Norm_data_r [N] at this time is calculated, the result is as shown in FIG. 10-4, and depending on the value of the threshold value Vthr, the light shielding part is detected in the D part. In other words, a change in the degree of the influence of the disturbance results in the output of coordinate values as if they were instructed even though they were not instructed (coordinate input), causing a big problem for the user. It will be.

  Of course, in order to avoid this phenomenon, Ref_data [N] and Bas_data [N], which are the initial data, may be updated as appropriate. However, if a coordinate input operation is performed during this update operation, erroneous detection will occur. For this reason, for example, it is necessary to make a setting so that the user intentionally shifts to the update operation mode using a switch unit or the like, and there is a problem that becomes a product specification forcing the suspension of the conference or the like.

  Therefore, the present invention is configured so that coordinates can be calculated with high accuracy without using this type of initial data update using the normalized signal obtained in FIG. 8-4 or FIG. 10-4. It is.

  FIG. 1 is an explanatory diagram for explaining this state, and illustrates signal processing when a one-stroke coordinate is input (for example, a character “one” is input). First, the normalized sensor signal output will be described. State (1) indicates that no coordinate input is performed, and no signal output is performed. In state (2), coordinate input at a desired position A is performed. This indicates that a light-shielding part has occurred. In the state (3), the pointing tool is still present at the desired position A, and the moving speed of the pointing tool is increased in the states (4) to (5) (the change in the position of the light shielding portion is gradually increased). On the other hand, from 5) to (7), the moving speed of the indicator gradually decreases, reaches the desired position B in the state (7), and the coordinate input operation at the desired position B is completed in the state (8). Thus, the state (9) waits for the coordinate input operation. In order to simplify the explanation, in each step ((1) to (9)), it is assumed that a signal corresponding to one sampling of the coordinate input device is continuously detected (that is, the coordinate sampling rate is 90 times / second). If the coordinate input device has the performance of (1) to (9), the time required to reach steps (1) to (9) is equivalent to 9 samplings, so the operation is completed in about 0.1 second).

  Next, the coordinate calculation signal Norm_data_Δ [N] will be described. By shifting from the state (1) to the state (2), a difference (2)-(1) between the two signals is obtained, which has been described above. By using the CCD pixel number determining method as an arrow point as a detection point and calculating position coordinates by a method described later, for example, a cursor or the like displayed on the display device is positioned at a desired position A. Next, in the case of the difference signal (3)-(2) (in the state of (2) and in the state of (3), the indicator is at the same position coordinate), no signal can be obtained. The coordinate input device does not detect the position coordinate, but the cursor is already positioned at the desired position A based on the calculation result of the difference (2) (1), so the operator calculates (sends) the coordinate by the coordinate input device. It is impossible to recognize the trouble caused by failure, that is, no trouble occurs in operation. Thereafter, as the pointing tool moves, signals (4)-(3), signals (5)-(4), signals (6)-(5), and signals (7)-(6) are obtained. In this case, an upward convex signal portion and a downward convex signal portion are obtained, and a threshold value is set for each (the first threshold value Vthup for detecting the upward convex portion, and the downward convex portion The second threshold value Vthlw for detecting the CCD pixel number is calculated by the method described above (see FIG. 9) for each convex part, and the CCD central pixel number of the obtained convex part is calculated. Similarly, it is possible to accurately calculate the position coordinates of the pointing tool by the method described later, using the median value of the downwardly convex portion as the CCD center pixel number as the detection CCD pixel number. In the case of the difference signal (8)-(7) (in the state of (7) and in the state of (8), the pointing device is at the same position coordinate), since the signal cannot be obtained, The input device does not detect the position coordinates, but in the state of the difference signal (9)-(8), the cursor moves to the desired position B. For example, the specifications leave the locus on the screen as the cursor moves. By doing so, the character “one” intended by the operator can be input at a desired position.

  Now, the advantage of the configuration and calculation in this way will be described with reference to FIG. 11. In the environment where the apparatus is installed, when the disturbance factor such as sunlight changes from when the initial data is set, the coordinates Even if the input is not performed, the normalized data Norm_data_r [N] becomes as shown in FIG. 11-1 (corresponding to FIG. 10-4), for example, and there is a risk of erroneous detection. However, there is no change in the disturbance factor (if there is a minute) until the next coordinate sampling time (for example, after 0.011 seconds for a coordinate input device at 90 sampling / second), As shown in 11-2, the normalized data Norm_data_r [N] has almost no change from the immediately preceding sampling result (corresponding to FIG. 11-1). Therefore, by calculating the difference Norm_data_Δ [N] between the two, a signal waveform as shown in FIG. 11-4 is obtained, and there is no light-shielding part even in a disturbance state different from when the initial data was acquired. Can be detected with high accuracy. FIG. 11-3 is the normalized data Norm_data_r [N] obtained when the light-shielding part due to the pointing tool or the like suddenly occurs in the state of FIG. 11-2, and the normalized data corresponding to FIG. 11-2 sampled immediately before. By calculating the difference from the data Norm_data_r [N], it is possible to obtain the coordinate calculation signal normalized data Norm_data_Δ [N] as shown in Fig. 11-5, and it is accurate without being affected by the change in disturbance. Thus, it is possible to obtain an excellent effect that only the light shielding portion of the pointing device can be obtained. Therefore, the operator only has to acquire the initial data that is performed only when the power is turned on, and can perform coordinate calculation with high accuracy even if the time of unnecessary light has changed and the state of unnecessary light has changed. Operability can be obtained.

  Furthermore, by comparing this coordinate calculation signal normalization data Norm_data_Δ [N] with the upper threshold value Vth1 or the lower threshold value Vth2 (see FIGS. 11-4 and 11-5), the above-described change in unnecessary light can be achieved. Even if there is, it is possible to determine whether a light-shielding part due to coordinate input has occurred without being affected by this, and according to the determination result, the CCD pixel number can be determined based on the first threshold Vthup and the second threshold Vthlw described above A configuration for calculating may be used.

  According to the configuration of the present application, if the processes of S206 to S210 are set at the time of shipment from the factory, S201 to S205 are passed through S201 to S205 at the time of start-up in the market. Since the initial data at the time of shipment from the factory may vary greatly depending on the installation environment, the calculated coordinate value is not output and the obtained Norm_data_r [N] is stored in Norm_Inidata_r [N] Then, returning to S211 and repeating the steps S211 to S220 according to the above description, the initial data setting only at the time of shipment by the factory may be employed.

  On the other hand, at start-up, assuming that the operator does not perform coordinate input operations, for example, the light intensity distribution is inspected, and if there are pixels with extremely low signal levels, a warning or failure specification may be considered. In this case, initial data (S206 to S210) may be stored simultaneously with the operation.

  Therefore, when the initial data setting specification for the factory is used, it is possible to obtain the advantage that the start-up time can be reduced, and it goes without saying that the specification may be selected according to the use of the product.

  In the above description, it is difficult to set the light quantity distribution Norm_data [N] to a constant value, and various processes are performed using the normalized signal. However, the light quantity distribution Norm_data [N ] Can be configured to a constant value, the necessity of normalization processing is reduced, and the light quantity distribution Norm_data [N] (n) obtained by the n-th sampling is stored as reference data at the time of the n + 1-th sampling, and n The CCD pixel number may be calculated based on the difference between the + 1st sampling data Norm_data [N] (n + 1) and the nth sampling data Norm_data [N] (n).

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

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

<Description of coordinate calculation method>
FIG. 13 is a diagram showing a positional relationship with the screen coordinates. The coordinate input effective area 3 is arranged with the X axis in the horizontal direction, the Y axis in the vertical direction, and the center of the coordinate input effective area 3 at the origin position. 1R is mounted symmetrically about the Y axis, and the distance between the sensor units is Ds. As shown in the figure, the CCD light receiving surface of the sensor unit 1 is arranged such that the normal direction forms an angle of 45 ° with the X axis, and the normal direction is defined as 0 ° (reference direction). To do. At this time, the sign of the angle is the clockwise direction in the case of the sensor unit 1L arranged on the left side, and the counterclockwise direction in the case of the sensor unit 1R arranged on the right side. Is defined as the “+” direction. Furthermore, P0 in the figure is the intersection point position of each sensor in the normal direction, and the distance from the origin in the Y-axis direction is defined as P0y. At this time, the angle P obtained by each sensor unit 1 is θL, θR, and the coordinates P (x, y) of the point P to be detected are

で得られる。

It is obtained by.

  FIG. 2 is a flowchart showing steps from data acquisition to coordinate calculation, and a series of processing steps of the coordinate input device of the present invention will be described in detail.

  First, when the power is turned on in S201, various initializations such as port setting and timer setting of the arithmetic control circuit and the like are performed in S202. Steps S203 to S205 are preparations for removing unnecessary charges of the CCD performed only at startup. In a photoelectric conversion element such as a CCD, unnecessary charge may be accumulated when it is not operated, and if the data is used as it is as reference data, it becomes impossible to detect or causes erroneous detection. In order to avoid this, the unnecessary charge accumulated in the CCD is removed by reading the data from the CCD a predetermined number of times in step S203 (S204) in a state where the light projecting means is not illuminated. Yes. S205 is a judgment sentence for repeating a predetermined number of times. S206 is data acquisition in a state where the light projecting means is not illuminated, which corresponds to the acquisition of Bas_data [N] described above as reference data, is stored in the memory in S207, and is used for subsequent calculations.

  In S208, reference data Ref_data [N] corresponding to the initial light amount distribution when illuminated by the light projecting means is fetched and similarly stored in the memory in S209. Subsequently, the difference value between Bas_data [N] and Ref_data [N] obtained in S210 and the normalized initial data Norm_Inidata_r [N] are calculated, and the result is stored in the memory in S211.

  The above steps are the initial setting operation when the power is turned on. Needless to say, this initial setting operation may be configured to operate according to the operator's intention using a reset switch or the like. Through this initial setting operation, the state shifts to a normal capturing operation state.

  First, in S212, the light quantity distribution Norm_data [N] is fetched, and in S213, normalized data Norm_data_r [N] is calculated using the difference value from Ref_data and Bas_data [N], and the normalization stored in S214 A difference value Norm_data_Δ [N] from the initial data Norm_Inidata_r [N] is calculated, and by comparing the signal level with, for example, a predetermined threshold value (Vth1 or Vth2), it is determined whether or not coordinate input is performed (S215). ).

  If it is determined that coordinate input has not been performed, the process jumps to S220, but if it is determined that coordinate input is present, based on Norm_data_Δ [N] obtained in S214 in S216, the signal feature point (for example, the signal A rising portion, a falling portion, and a center position and a gravity center position based on the information are determined, and a CCD output pixel number is calculated and determined. For example, Tan θ is calculated from the obtained pixel number from an approximate polynomial (S217), and x and y coordinates are calculated from the Tan θ values obtained by the left and right sensor units using equations (8) and (9) (S218). The data is transmitted to an external device such as a host PC (S219). The means may be sent by any interface such as serial communication such as USB, RS232C, etc., and the normalized data (obtained in S213) obtained in S220 after the processing is completed is normalized initial data Norm_Inidata_r [ N] is updated (S220), the updated result is stored in S211 and the routine (S211 to S220) is repeated for the next coordinate calculation. Thereafter, this process is repeated until the power is turned off or the reset state is set by the operator's intention. If this repetition cycle is set to about 10 [msec], the coordinate input device of the present invention can output the coordinates indicated by the finger or the pointing tool 5 to an external device or the like at a cycle of 100 times / second.

The timing chart explaining the signal treatment of this invention. The flowchart explaining the outline of coordinate calculation. The schematic block diagram of the coordinate input device of this invention. Explanatory drawing explaining the light projection means in the sensor unit 1. FIG. Explanatory drawing explaining the detection means in the sensor unit 1. FIG. FIG. 3 is a block diagram of the control / arithmetic unit 2. Light emission timing chart. An example of light quantity distribution and signal processing. Explanatory drawing explaining the detailed pixel number determination method. Explanatory drawing explaining the malfunction of a prior art example. Explanatory drawing explaining the effect of this invention. Explanatory drawing of the relationship between pixel number N and angle (theta). Explanatory drawing of coordinate calculation.

Explanation of symbols

1L, 1R sensor unit 2 control unit 3 coordinate input effective area 4 retroreflective member 5 light shielding member

Claims (3)

At least two light receiving detection means are provided at the corners of the coordinate input effective area, and has an angle detection means for detecting the direction indicated by the finger or the pointing tool from the change in the light amount distribution detected by the light receiving means, A coordinate input device that calculates position coordinates instructed by the finger or pointing tool based on a plurality of derived angle information,
Angle detection means for detecting the direction indicated by the finger or the pointing tool from the difference information between the output result of the detection means sampled for position coordinate calculation and the output result of the detection means sampled immediately before the sampling The coordinate input device characterized by having.   2. The coordinate input device according to claim 1, wherein the reference data storage means stores the output result of the detection means at the time of the nth light projection by the light projecting means as reference data, and the n + 1th sampling time. Angle detection means for calculating the direction indicated by a finger or an indicator from the difference between the output result of the detection means at the time of light projection and the output result stored in the storage means, and the number of times of sampling n A coordinate input device comprising reference data update means for updating the output result of the detection means at the time of + 1st light projection as the reference data and storing the result again in the reference data storage means.   3. The coordinate input device according to claim 1 or 2, wherein the light output by the light projecting means is not illuminated when the coordinate input by a finger or an indicator is not performed. A coordinate input device further comprising storage means for storing the result and the output result of the detection means when light projection is performed by the light projection means, or difference information between the two.

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