JP4229964B2 - Position detection device using area image sensor - Google Patents

Description

  The present invention relates to a position detection device that detects an indicator positioned on a detection surface, and more particularly to a position detection device that uses an area image sensor in an imaging unit.

  There are various types of position detection devices that detect an indicator positioned on the detection surface, such as an electromagnetic induction type, a pressure sensitive type, and an optical type. The electromagnetic induction threshold value detection device obtains a two-dimensional coordinate from a planar distribution of radiation intensity of electromagnetic waves radiated from an indicator itself. This method requires a dedicated indicator that emits electromagnetic waves, and cannot be input with a finger or the like.

  In the pressure-sensitive position detection device, a resistance film or the like is arranged on a detection surface, and an indication position of an indicator is detected by the resistance film or the like and an indication position coordinate is output. However, the pressure-sensitive position detection device has a problem that the detection surface is broken if a sharp indicator is used. Further, when applied to a so-called touch panel display device combined with a display device, the display screen is seen through a resistance film or the like.

  The optical position detection apparatus images a pointer placed on a detection surface from two locations by two imaging units, and obtains the pointing position coordinates of the pointer based on the principle of triangulation. For this, the shape of the indicator is detected by image recognition or the like, the indicated position coordinates are output, and a retroreflective member that reflects the incident light in the incident direction is provided around the indicator or the detection surface, In some cases, light is emitted from a light source to output the indicated position coordinates from the position of a portion with light or a shadow portion. FIG. 1 is a top plan view of a shielded optical position detection device that detects the pointing position of a pointer using the principle of triangulation. An indicator 2 such as a finger placed on the detection surface 1 is imaged by the two imaging units 3. For example, the imaging unit 3 is provided with a light source such as an LED so that light is emitted toward the detection surface 1, and the light is incident on the retroreflective frame 4 and reflected back in the incident direction. Is imaged by the sensor of the imaging unit 3. When the indicator 2 is placed on the detection surface 1, the portion becomes a shadow and is imaged by the imaging unit 3, so that the indicated position coordinates can be calculated from the position of the shadow portion using the principle of triangulation It is. Since these optical position detection devices may have a detection surface that is hard such as protective glass, it is also possible to use a sharp pointed indicator, and even when applied to a touch panel display device, the display is affected. Can be applied conveniently. Furthermore, it can be applied to a large display device such as a plasma display, and it is considered that the demand for optical position detection devices will increase more and more in the future.

  The sensor of the image pick-up part used for these apparatuses is normally comprised with the linear image sensor. This is because information on the height direction is basically unnecessary in the detection of the indicator, and it is only necessary to detect the position of the shadow or light in the horizontal direction.

  However, in the optical position detection device, it is very difficult to align the imaging unit used for the optical position detection device. That is, since the linear image sensor is a sensor composed of one line, it has been difficult to align the field of view of the imaging unit by this one line in parallel with the detection surface and closer to the detection surface. As a solution to such a problem that it is difficult to adjust the mounting angle and the mounting position, there is one in which the height and inclination of the imaging unit can be finely adjusted with a screw.

JP-A-62-2428 JP-A-11-85377 JP 11-85399 A

  As described above, it is very difficult to adjust the mounting position of the imaging unit in the optical position detection device. Even if a mechanism that can adjust the height and inclination with screws is provided, it is difficult for an amateur to accurately align the field of view of the imaging unit in parallel with the detection surface, even if it is accurately adjusted at the time of product shipment, The position may be distorted at the time of installation, and when applied to a large detection surface, the position of the imaging unit may change due to deformation of the detection surface due to a temperature change and the field of view may shift. In such a case, it is almost impossible to perform alignment on the end user side, and it has been necessary to make adjustments by maintenance service or the like.

  It is also conceivable to widen the field of view of the imaging unit in the vertical direction of the detection surface by widening the angle of view of the imaging lens so that the positioning of the imaging unit does not become severe. FIG. 2 is a view of the position detection device as shown in FIG. 1 as viewed from the side. As shown in the drawing, the field of view 5 of the image pickup unit 3 is expanded in the vertical direction by an imaging lens or the like so that the retroreflective frame 4 is included in the field of view even if the mounting position of the image pickup unit 3 is shifted. It is possible to do. However, when the field of view is widened in the vertical direction, it is affected by external light and the like. That is, in order to detect the position, it is necessary to detect the shadow of the indicator 2 only in the vicinity of the detection surface 1, but by expanding the field of view, it is caused by extraneous light other than the indicator, for example, light from the sun, fluorescent light, etc. In some cases, a shadow is mistakenly recognized as a shadow caused by an indicator, and erroneous coordinates are output. For this reason, it has been difficult to widen the field of view of the imaging unit in the direction perpendicular to the detection surface. In addition, instead of an example of providing a retroreflective frame around the detection surface, there is also an example in which a retroreflective member is provided on the indicator and a light portion is detected to calculate the indication position of the indicator. If there is extraneous light, it cannot be distinguished from the indicator itself and will be mistaken. In order to eliminate the influence of extraneous light, it is conceivable to raise the frame. However, if a very high frame is provided, there is a problem that the operability is deteriorated.

  Further, in order to increase the detection accuracy of the designated position coordinates, it is necessary to align the field of view of the imaging unit as close to the detection surface as possible and close to the detection surface. Adjusting the field of view to a position close to the detection surface may result in misunderstanding that the indicator has touched the detection surface when it is not touching, or the detection position and the detection surface may be misaligned when touching the detection surface diagonally. This is important in order to eliminate the error of the indicated position coordinates due to the fact that However, when the detection surface becomes larger, it may be affected by the flatness. As shown in FIG. 3, when the detection surface 1 is distorted, the field of view 5 is interrupted by the distortion of the detection surface halfway, and cannot reach the retroreflective frame 4. In this case, the entire detection surface cannot be detected. Therefore, in order to be able to detect the entire detection surface, it is conceivable to increase the position of the imaging unit 3 and to look down on the detection surface from an obliquely upward direction. However, when the position of the imaging unit 3 is raised and looked down, the retroreflective frame 4 at the corner portion of the detection surface 1 appears to be refracted as shown in FIG. In such a case, in the linear image sensor constituted by one line, since the field of view is also a straight line, it becomes impossible to image the entire retroreflective frame 4 that appears to be refracted.

  Note that it is also conceivable that the detection surface is imaged with a wide field of view by a camera using an area image sensor or the like, sent to the image processing unit, and processed for image detection to detect the designated position coordinates. However, in order to detect the designated position coordinates, a frame rate of about 100 frames per second is required, so the amount of data sent from the area image sensor to the image processing unit is enormous, and a high-speed interface is required to process it. And a processing device are required, which increases the product cost and is not realistic.

  In view of such circumstances, the present invention provides a position detection device that does not require adjustment of the mounting position of the imaging unit, is easy to maintain, is not affected by environmental changes such as temperature changes, and can be realized with inexpensive components. It is something to try.

In order to achieve the above-described object of the present invention, according to the present invention, there is provided a position detection device for detecting an indicator positioned on a detection surface, the position detection device comprising:
A pair of imaging units having an area image sensor and an imaging lens in which photosensitive elements are two-dimensionally arranged, and imaging the detection surface from two positions on the side of the detection surface with a certain visual field and outputting an image signal When,
Marker means serving as a reference for defining a predetermined portion at a position close to the detection surface in the certain visual field imaged by the imaging unit;
An image signal output from the imaging unit is input, a predetermined portion of the image signal is demarcated based on the marker means, and an indication position on the detection surface indicated by the indicator using the image signal of the demarcated predetermined portion Image processing means for calculating the coordinates of
Tracking means for automatically detecting a change in the position of the marker means and redefining a predetermined portion at predetermined intervals when no indicator is detected on the detection surface;
There is provided a position detecting device characterized by comprising:

  Here, the imaging unit may further include a light source that emits light along the detection surface, and the light source may be disposed in the vicinity of the imaging lens.

  Furthermore, a retroreflective member that retroreflects light may be used, and the retroreflective member may be provided on the indicator or continuously on at least three sides of the detection surface.

  Moreover, the specific visual field corresponding to the specific pixel may be an area including a part or all of the image of the retroreflective member.

  Furthermore, it may have marker means as a reference for defining a specific field of view imaged by the imaging unit, and the selection means may select a specific pixel corresponding to the specific field of view from the photosensitive element on the basis of the marker means. The marker means may be arranged at least at four locations on the detection surface.

  Further, the marker means may be a retroreflective member configured such that the reflected image has a characteristic shape, or may be a light emitting unit that emits light.

  Here, the light emitting unit may be configured such that the light emission image has a characteristic shape, or may be configured to emit light only when defining a specific field of view.

  Further, it may include calibration means, and the calibration means may automatically cause the selection means to select a specific pixel at a predetermined interval or manually.

  Further, the specific pixel selected by the selection unit can be selected from a pixel arranged in a straight line in accordance with the pixel arrangement, a pixel arranged obliquely, or a pixel arranged with a refracted portion.

  Furthermore, it has a memory which memorize | stores the pixel selection information regarding the specific pixel selected by the selection means, and the selection means uses the pixel selection information stored in the memory to convert the image signal captured by the imaging unit to the specific pixel. A corresponding specific image signal may be output.

  Furthermore, it has a buffer memory that temporarily stores the image signal picked up by the image pickup unit, and the selection unit uses the pixel selection information stored in the memory to correspond to the specific pixel from the image signal stored in the buffer memory. The specific image signal to be output may be output.

  Here, the memory may be a serial access type memory, and the stored pixel selection information may be configured to be read in synchronization with an input clock signal.

  Further, the selection unit and the image processing unit may be connected by a high-speed serial transfer interface, and the image processing unit may be included in a personal computer.

  Further, the image processing means may be configured by a microcomputer, and the coordinates of the designated position may be output via an interface included in the microcomputer.

  Furthermore, it may be configured to have a display device, and the detection surface may be formed of a transparent plate that protects the display surface of the display device.

  According to the present invention, a position detection apparatus for detecting an indicator positioned on a detection surface has an area image sensor and an imaging lens in which photosensitive elements are two-dimensionally arranged. A pair of imaging units for imaging the detection surface with a certain visual field and outputting an image signal, marker means serving as a reference for defining a predetermined portion of the certain visual field captured by the imaging unit, and the imaging The image signal output from the unit is input, a predetermined portion of the image signal is defined based on the marker means, and the coordinates of the indicated position on the detection surface indicated by the indicator using the image signal of the defined predetermined portion And an image processing means for calculating the position and a tracking means for automatically redefining a predetermined portion by detecting a change in the position of the marker means automatically at a predetermined interval or manually. .

  According to the above means, the following operation can be obtained. In other words, it is not necessary to adjust the mounting position of the imaging unit, and instead of adjusting the mounting position, it is only necessary to select a specific pixel of the area image sensor, so that the number of assembly steps can be reduced and the maintainability is also improved. Is obtained. Even if the image pickup unit is attached with an inclination, it is only necessary to select pixels arranged obliquely with respect to the pixel arrangement of the area image sensor. In addition, since it is possible to select a refracted portion instead of a straight line, even when the detection surface is warped, the imaging unit is provided at a slightly higher position so that the entire detection surface can be detected. Is also easy. Furthermore, since the field of view of the imaging unit can be easily set lower than the detection surface, the detection accuracy is improved and the operability is improved. Even if an area image sensor is used, only a specific image signal corresponding to a specific pixel is image-processed, so that a dedicated high-speed interface and an expensive processing device are not necessary and can be manufactured at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 5 is a top plan view of the position detection apparatus of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components, and the basic configuration is the same as the conventional one shown in FIG. 5 mainly illustrates an example in which the retroreflective frame 4 is provided on at least three sides around the detection surface 1 and the position of the shadow blocked by the indicator 2 such as a finger is detected by the imaging unit 7. The present invention is not limited to this, and the indicator 2 may be provided with a retroreflective member, and the position of light by the retroreflective member may be detected by the imaging unit 7. Further, a retroreflective member is not particularly used, and a method of detecting that the indicator 2 is placed on the detection surface 1 by image processing of an image picked up by the image pickup unit 7 or a light source provided in the pointer itself. Of course, a method of detecting the position of the light is also possible. The most characteristic feature of the present invention is that an area image sensor in which photosensitive elements are two-dimensionally arranged in the imaging unit 7 is used, and a selection means for selecting a specific field among the fields captured by the imaging unit 7. The control unit 10 is provided. Hereinafter, these will be described more specifically.

  The imaging unit 7 used in the position detection apparatus of the present invention is mainly composed of an area image sensor in which photosensitive elements are two-dimensionally arranged and an imaging lens, and is arranged at two positions on the side of the detection surface 1. . Then, the detection surface is imaged from two locations and an image signal is output. In the case of a position detection device using a retroreflective member as shown in FIG. 5, a light source is required in the vicinity of the imaging lens. In the example illustrated in FIG. 5, the retroreflective frame 4 is continuously provided on at least three sides of the detection surface 1. This is because the shadow portion corresponding to the indicator 2 cannot be detected unless it is provided continuously in the frame.

  An example of the configuration of the imaging unit 7 will be described with reference to FIG. FIG. 6 is a configuration example of the imaging unit 7 that can be used in the position detection device of the present invention. FIG. 6A is a top plan view thereof, and FIG. 6B is a side view thereof. As illustrated, the imaging unit 7 includes an area image sensor 70, an imaging lens 71, and a light source 72. The area image sensor 70 can use various sensors such as a CCD system and a CMOS system. In addition, not only outputting image signals corresponding to all pixels of the area image sensor, but also a sensor having a mode that can be restricted to a part of the region can be used. The area image sensor used in the position detection apparatus of the present invention is preferably a CMOS area image sensor that does not require an A / D converter or the like that requires high-speed operation. This makes it possible to reduce product costs. For example, an LED or the like can be used as the light source 72, and two light sources are provided in the illustrated example. However, the present invention is not limited to this, and the number of light sources may be one. The number and arrangement of the light sources can be variously changed according to the size of the detection surface. 6 shows an example in which the prism mirror 73 is used in order to reduce the size of the image pickup unit. However, the present invention is not limited to this, and the imaging lens and the area image sensor can be used without using the prism mirror. Of course, it does not matter if they are arranged. Further, the imaging lens 71 has a wide field angle in a direction parallel to the detection surface 1 and is configured to have a field of view so that the entire detection surface 1 can be imaged. Note that the angle of view in the direction perpendicular to the detection surface 1 of the imaging lens 71 is not particularly limited because the field of view of the area image sensor can be controlled as will be described later, and an appropriate angle of view may be arbitrarily determined. .

  In the imaging unit 7 configured as described above, light from the light source 72 is emitted along the detection surface parallel to the detection surface 1 and enters the retroreflective frame 4. Since the retroreflective frame 4 reflects light in the incident direction, the retroreflective frame 4 returns to the imaging unit 7 along the detection surface 1 again. This light is collected by the imaging lens 71, refracted by 90 degrees by the prism mirror 73, and an image of the retroreflective frame is formed on the area image sensor 70. Then, the area image sensor outputs an image signal.

  The image signal output by the area image sensor is sent to the control unit 10. The control unit 10 includes a selection unit that selects, from the photosensitive element, a specific pixel corresponding to a specific field among the fields captured by the imaging unit 7. Specifically, a selection that can select only a specific pixel corresponding to a specific visual field, that is, a specific pixel corresponding to the visual field that can capture the retroreflective frame 4 from all the photosensitive elements of the area image sensor 70. Have means. For example, in addition to the retroreflective frame 4, the upper part and the detection surface 1 enter the field of view of the imaging unit 7, but only the image portion of the retroreflective frame 4 is necessary for detecting the position of the indicator. . Therefore, a specific pixel corresponding to a specific field of view of the image portion of the retroreflective frame 4 may be selected. Since the selection means can select any specific pixel of the photosensitive element of the area image sensor, it is not necessary to select a portion corresponding to the entire image of the retroreflective frame 4, and a portion closer to the detection surface 1 By selecting a pixel corresponding to the image of the retroreflective frame, a position detection device with high detection accuracy and good operability can be realized.

  Then, a specific image signal corresponding to the selected specific pixel is sent from each of the left and right imaging units 7 to the personal computer 11 via a high-speed serial transfer interface means such as USB. Since the specific image signal is data of only a portion corresponding to a specific visual field, a dedicated high-speed interface or the like is unnecessary, and a general interface such as USB can be used. The personal computer 11 can be used as the image processing unit. The personal computer 11 performs image processing based on the transmitted image signal and outputs the coordinates of the indicated position on the detection surface indicated by the indicator. . Specifically, the coordinates on the detection surface 1 are calculated based on the principle of triangulation from the positions of the shadow portions included in the specific image signals from the left and right imaging units 7. For example, when the position detection device of the present invention is applied to a touch panel display device, the detection surface 1 may be formed of a transparent plate, and then the display device 12 may be arranged with the display screen overlapped.

  Next, the selection means provided in the imaging unit of the position detection apparatus of the present invention will be described in detail with reference to FIG. FIG. 7 is a block diagram for explaining the control unit 10 used in the position detection apparatus of the present invention. Although there are two imaging units 7 on the left and right, each image signal process is the same, so only one side process will be described. The image signal from the area image sensor of the imaging unit 7 is temporarily stored in the buffer memory 20. As the buffer memory, it is preferable to use an SRAM or the like that has a relatively high writing / reading speed. The image signal stored in the buffer memory 20 may be an image signal corresponding to all the pixels of the area image sensor. However, if there is a mode that can limit the imaging range on the area image sensor side, the image signal is stored in such a mode. An image signal limited in advance to only a part of a rough area may be stored in the buffer memory 20. In addition to the image signal, a pixel clock signal in the image signal sent along the scanning line of the area image sensor is counted by the pixel counter 21, and this value is written in the buffer memory 20 as an address. The buffer memory 20 is connected to a microcomputer 22 that is a main part of the control unit 10. The microcomputer 22 has an interface such as a USB as a connection means with the personal computer 11. Furthermore, it also has a storage unit 23 such as an SRAM for storing pixel selection information set in the personal computer 11 by calibration or the like to be described later. Based on this pixel selection information, the microcomputer 22 reads out the specific image signal corresponding to the specific pixel from the buffer memory 20, that is, the image signal of the part necessary for detecting the indicated position coordinates, and sends it to the personal computer 11 via the interface. Send. A read / write command to the buffer memory 20 may be performed according to an instruction from the microcomputer 22. In the personal computer 11, the pointing position coordinates of the pointer are calculated from the sent image by driver software or the like.

  Next, the detection procedure of the position detection apparatus of the present invention will be described with reference to FIG. FIG. 8 is a flowchart for explaining a detection procedure in the position detection apparatus of the present invention shown in FIG. First, a pixel area selection procedure described in detail later is performed (step 801). This is performed in order to determine a specific pixel of the area image sensor corresponding to a specific field of view of the imaging unit 7. When the specific pixel is determined, the microcomputer 22 reads the specific image signal corresponding to the specific pixel from the buffer memory 20 such as the SRAM with reference to the address based on an instruction from the upper personal computer 11 (step 802). . The read specific image signal is transmitted to the personal computer 11 via the interface. As a result, the position on the detection surface 1 can be detected. Then, the personal computer 11 refers to the transmitted specific image signal and determines whether or not the indicator is detected (step 803). In the position detection apparatus of FIG. 5, when the indicator 2 is placed on the detection surface 1, the position of the shadow is detected by the left and right imaging units 7. From these shadow positions, the indicated position coordinates of the indicator 2 are calculated by the principle of triangulation (step 804). Then, returning to step 802, the position detection is continued. In the case of an example in which a retroreflective member is provided on the indicator 2 without using the retroreflective frame 4, the position of the light is detected when the indicator is placed, and the coordinates are determined from the position of the light. Will be calculated.

  If the indicator 2 is not detected in step 803, it is determined whether the undetected state has continued for a predetermined time (step 805). If it is before the predetermined time has elapsed, the process returns to step 802 and continues to perform position detection. In step 805, if the predetermined time has elapsed, the process returns to step 801, and the pixel area selection procedure is performed to determine the specific pixel again. This makes it possible to readjust the field of view in accordance with the change in the field of view of the image pickup unit due to fine movement of the image pickup unit due to a temperature change or the like. That is, when not used for a predetermined time, the calibration is automatically performed using the time. Although the calibration is automatically performed in the illustrated example, the present invention is not limited to this, and it is of course possible to manually select a specific pixel.

  Next, details of the pixel region selection procedure will be described with reference to FIG. FIG. 9 is a flowchart for explaining a pixel region selection procedure in the position detection apparatus of the present invention. First, based on an instruction from the personal computer 11, the microcomputer 22 reads out image signals of all pixels corresponding to the imaging field of view of the imaging unit 7 from the buffer memory 20 (step 901). The read image signal is transmitted to the personal computer 11 via the interface, and the personal computer 11 determines a specific field of view of the imaging unit 7 based on this image (step 902). When the specific field of view is determined, the specific pixel of the photosensitive element of the area image sensor corresponding to the specific field of view is selected (step 903). The personal computer 11 transmits pixel selection information related to the specific pixel selected in this way to the microcomputer 22 via the interface, and the microcomputer 22 stores the pixel selection information in the internal storage unit 23 (step 904). ).

  Hereinafter, the above steps will be described more specifically. For example, when the imaging unit 7 is installed so as to have a field of view substantially parallel to the detection surface 1, the image captured by the imaging unit 7 read out in step 901 is as shown in FIG. In the figure, A, B, and C correspond to positions A, B, and C attached to the retroreflective frame 4 in FIG. Referring to FIG. 10, the part of the retroreflective frame 4 is a brightly detected part. However, when the detection surface 1 is reflected by a protective glass or the like, a bright part is also present on the detection surface 1 side as shown in the figure. Is reflected, and becomes a state like a large band of light. Accordingly, since the portion necessary for detecting the position of the indicator 2 is a portion above the horizontal center line of the light band portion, the positions corresponding to all the light band portions above the center line are set. What is necessary is just to determine as a specific visual field (step 902). In addition, in order to further reduce the data to be transmitted, it is not necessary to make the area including all the portions corresponding to the retroreflective frame 4 a specific field of view. It is preferable that the portion has a specific visual field because operability is improved. Therefore, since the closer the detection area is to the detection surface, the false detection of the indicator and the error can be reduced. Therefore, a portion as close to the center line as possible should be determined as the specific area.

  When a specific field of view is determined, in step 903, a specific pixel of the photosensitive element of the area image sensor corresponding to the specific field of view is selected. The specific pixel may be selected linearly in accordance with the pixel arrangement of the photosensitive elements of the area image sensor. However, in the case where the imaging unit is provided with an inclination, the pixels arranged diagonally may be selected. However, if the specific field of view is not linear due to distortion of the detection surface or the like, the pixel may be selected along the distortion.

  Further, as shown in FIG. 11 (a), in order to avoid that the retroreflective frame does not enter the field of view due to distortion of the detection surface 1 or the like and the indicator cannot be detected, the installation position of the imaging unit 7 is increased. In this case, the image captured by the imaging unit 7 is as shown in FIG. In the figure, A, B, and C correspond to positions A, B, and C attached to the retroreflective frame 4 in FIG. In this way, the retroreflective frame 4 at the corner of the detection surface 1 appears to be refracted, but as shown in FIG. 11C, a specific pixel is selected to have a refracted portion. As a result, the retroreflective frame 4 can be accurately set to a specific field of view. In step 904, pixel selection information for the specific pixel is stored in the storage unit 23 of the microcomputer 22.

  Next, the processing procedure of the microcomputer 22 will be described. FIG. 12 is a flowchart for explaining a processing procedure in the microcomputer 22 used in the position detection apparatus of the present invention. First, the microcomputer 22 waits for data from the personal computer 11 (step 1201). If the sent data is pixel selection information (step 1202), the microcomputer 22 stores the pixel selection information in the storage unit 23 (step 1203). ). If the sent data is not pixel selection information (step 1202), the buffer memory 20 stores the image signals from the two imaging units 7 in a continuous area according to the addresses generated by the pixel counter 21. Write (step 1204). If the command from the personal computer 11 is an image request, it is determined whether it is an all-image request or a specific image request (step 1205). If it is an all-image request for calibration, all images in the buffer memory are requested. A signal is transmitted to the personal computer 11 via the interface (step 1206). If the command from the personal computer 11 is a specific image request, a specific image signal corresponding to the selected specific pixel is read by randomly accessing and reading the buffer memory based on the pixel selection information stored in the storage unit 23. Is transmitted to the personal computer 11 via the interface (step 1207).

  As described above, the position detection device of the present invention does not require strict alignment or the like with respect to the mounting position of the imaging unit, so that the manufacturing cost is reduced and the maintainability is improved. Further, since only a specific image signal of a specific pixel necessary for position detection is transmitted, a dedicated high-speed interface or the like is not necessary. Furthermore, since coordinates are calculated on the personal computer side, a dedicated expensive processing circuit is not required. Furthermore, since the field of view of the imaging unit can be adjusted to a position as close to the detection surface as possible without adjusting the physical position of the imaging unit, the detection accuracy can be increased and the operability is also improved. improves.

  In the above-described example, the blocking position detection device is described in which the retroreflective frame is provided around the detection surface, and the position of the shadow where the light from the retroreflective material is blocked is detected by the imaging unit. Instead, a retroreflective member 13 is provided on the indicator 2 and a light emission type position detecting device that detects the position of a portion of the retroreflective member that shines in the imaging unit will be described with reference to FIG. FIG. 13 is a diagram for explaining an example when the position detection apparatus of the present invention is applied to another method. In the figure, the same reference numerals as those in FIG. 5 denote the same components, and the basic configuration is the same as the example shown in FIG. Further, the processing procedure and the like are basically the same as the procedures shown in FIGS. In the present embodiment, the determination procedure in the process of determining the specific field of view of the imaging unit in step 902 of FIG. 9 is different from the above-described embodiment. In this embodiment, since there is no retroreflective frame, a specific field of view cannot be determined in advance by the retroreflective frame. Instead, a marker member serving as a reference for defining a specific field of view of the imaging unit 7 is provided around the detection surface 1. As shown in the figure, marker members 14 are provided at at least four locations on the detection surface 1. A, B, and C attached to the marker member are markers imaged by the right imaging unit 7. The marker member 14 is a retroreflective member configured such that, for example, as shown in FIG. 14A, the reflected image has a characteristic shape, for example, a shape such as a triangle different from the tip shape of the indicator 2. Moreover, as shown in FIG.14 (b), what comprised the retroreflection member in stripe form etc. may be sufficient. That is, as long as it is configured to be a characteristic image that is not mistaken for the image of the indicator 2 placed on the detection surface 1, various shapes are possible without being specified as the shape in the illustrated example. Furthermore, the marker member 14 may use a light emitting source such as an LED instead of a retroreflective member. In this case, it is conceivable to configure the emission image to have a characteristic shape, but it may be configured to emit light only when defining a specific field of view of the imaging unit 7, that is, during calibration. . By doing so, the light source is not affected when the indicator is detected, and the power consumption can be suppressed.

  In the position detection apparatus configured as described above, an image in the visual field of the imaging unit 7 is as shown in FIG. Therefore, in step 902 for determining a specific field of view of the imaging unit 7 in FIG. 9, the line connecting the images of the marker members 14 may be determined as the specific field of view.

  In addition, even when the field of view of the imaging unit changes due to fine movement of the imaging unit due to temperature changes, etc., or the detection surface, etc., a tracking function is applied to detect the change in the position of the marker member and readjust the field of view. It is also possible to do. This follow-up function may be automatically activated at regular intervals, or may be manually activated arbitrarily.

  Next, another example of the control unit 10 used in the position detection apparatus of the present invention will be described with reference to FIG. The control unit 10 described with reference to FIG. 7 has a configuration using a buffer memory and a pixel counter. However, the control unit 29 shown in FIG. 16 is different in that a serial access type memory is used instead. It is. In addition, the control unit 29 shown in FIG. 16 includes a microcomputer for image processing so as to perform image processing with the microcomputer. However, the present invention is not limited to this, and as described with reference to FIG. 7, the image processing may of course be performed by a host personal computer. In the following description, there are two imaging units 7 on the left and right, but since the image signal processing is the same, only the processing on one side will be described.

  Image signals (image data) corresponding to all the pixels from the area image sensor of the imaging unit 7 are input to the image processing microcomputer 32. If there is a mode in which the imaging range can be limited on the area image sensor side, an image signal limited in advance to only a part of the rough area may be input in such a mode. Also, the pixel clock signal in the image signal sent along the scanning line of the area image sensor is input to one of the input side of the serial access storage unit 30 and the AND circuit 31. Then, a read signal which is an output of the serial access type storage unit 30 is input to the other input side of the AND circuit 31, and an output of the AND circuit 31 is input to the image processing microcomputer 32. Here, the storage unit 30 of the serial access method is specifically a memory that can read and write 1-bit information sequentially in synchronization with the input clock, and the pixel selection information stored in advance is, for example, an input clock It is read as a read signal at the rising edge of the signal. As the serial access type storage unit, for example, a serial flash memory manufactured by ST Microelectronics Co., Ltd. can be used. Hereinafter, the operation timing of each signal will be described with reference to FIG.

  FIG. 17 is a timing chart for explaining the operation timing of each signal of the control unit shown in FIG. As shown in the figure, the image data is switched every time the pixel clock signal rises. Since the pixel selection information stored in advance at the rising edge of the pixel clock signal is read from the serial access type storage unit 30 as a read signal, the read signal is, for example, as illustrated. Therefore, the output of the AND circuit 31 becomes HIGH when both the pixel clock signal and the readout signal are HIGH. The image processing microcomputer 32 extracts image data when the image data is in a stable state, that is, at the falling edge of the AND circuit output.

  A processing procedure of the control unit 29 configured as described above will be described below. The image processing microcomputer 32 performs substantially the same processing as the image processing procedure described with reference to FIGS. Therefore, first, a specific pixel corresponding to a specific visual field is determined by the pixel region selection procedure (step 801). The procedure for determining the specific pixel may be appropriately determined from the image of the retroreflective frame or the image of the marker means as in the procedure described above. Since the image signal is always input to the image processing microcomputer 32, the control unit 29 of this embodiment may determine a specific pixel using the image signal. Then, pixel selection information related to the determined specific pixel is stored in advance in the storage unit 30 of the serial access method. When detecting the pointing position coordinates of the pointer, the output of the AND circuit 31 is HIGH when both the read signal of the serial access type storage unit 30 and the pixel clock signal are HIGH, so the output of the AND circuit 31 is HIGH. At this time, the image signal is preferably extracted at a falling timing at which the image signal is stabilized. Thereby, the specific image signal corresponding to the specific pixel selected by the pixel selection information is input. The image processing microcomputer 32 performs image processing based on this specific image signal, and outputs the pointing position coordinates of the pointer from the location of the shadow or light by the pointer. In the example of FIG. 16, since coordinate data with a small capacity is output, the coordinate data is transmitted to a higher-order personal computer or the like via a low-speed interface such as RS-232C. Instead of using an image processing microcomputer that performs coordinate calculation, a microcomputer that simply performs extraction of a specific image signal may be used. In this case, the specific image signal may be transmitted to the personal computer via the interface, and image processing such as coordinate calculation may be performed on the personal computer side.

  With this configuration, it is possible to use a memory having a smaller capacity than the buffer memory as in the example described with reference to FIG.

  Note that the position detection device of the present invention is not limited to the illustrated examples described above, and it is needless to say that various changes can be made without departing from the scope of the present invention. As long as an area image sensor is used for the image sensor of the imaging unit and a means that can select a pixel corresponding to a specific field of view is used, the position detection method can be a blocking method, a light emitting method, or any other method. good.

  As described above, according to the position detection device of the present invention, it is not necessary to adjust the mounting position of the imaging unit, it is easy to maintain, it is not affected by environmental changes such as temperature changes, and can be realized with inexpensive components. An excellent effect of providing a simple position detecting device can be achieved. In the position detection device of the present invention, it is possible to easily determine a specific field of view of the imaging unit. Therefore, it is easy to provide a position detection device retrofitted to an existing display device to make a touch panel display device. . Furthermore, since a specific field of view can be defined effectively even if the retroreflective frame is narrow, it is possible to realize an easy-to-use position detection device that is less likely to become an operational obstacle.

FIG. 1 is a top plan view for explaining the configuration of a general shielding optical position detection device that detects the pointing position of a pointer using the principle of triangulation. FIG. 2 is a diagram of the position detection device shown in FIG. 1 viewed from the lateral direction. FIG. 3 is a diagram for explaining the influence on the field of view of the imaging unit when the detection surface is distorted. FIG. 4 is a diagram for explaining an image picked up by the image pickup unit in a case where the image pickup unit is configured to be looked down at a high position. FIG. 5 is a top plan view of the position detection apparatus of the present invention. FIG. 6 is a diagram for explaining an example of the configuration of an imaging unit used in the position detection device of the present invention. FIG. 7 is a diagram for explaining an example of a configuration of a control unit used in the position detection device of the present invention. FIG. 8 is a flowchart for explaining the procedure for detecting the pointing position of the pointer in the position detection apparatus of the present invention. FIG. 9 is a flowchart for explaining a pixel region selection procedure of the position detection apparatus of the present invention. FIG. 10 is a diagram for explaining an image captured by an imaging unit installed so as to have a visual field parallel to the detection surface. FIG. 11 is a diagram for explaining a specific pixel that is selected when the position of the imaging unit is configured to be looked down. FIG. 12 is a flowchart for explaining a processing procedure in the microcomputer used in the position detection apparatus of the present invention. FIG. 13 is a diagram for explaining an example when the position detection apparatus of the present invention is applied to another method. FIG. 14 is a diagram for explaining an example of a marker member used in the position detection device shown in FIG. FIG. 15 is a diagram for explaining an image captured by the imaging unit when a marker member is used. FIG. 16 is a diagram for explaining an example of another configuration of the control unit used in the position detection device of the present invention. FIG. 17 is a timing chart for explaining the timing of each signal in the control unit configured as shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection surface 2 Indicator 3 Imaging part 4 Retroreflective frame 5 Field of view 7 Imaging part 10 Control part 11 Personal computer 12 Display apparatus 13 Retroreflective material 14 Marker member 20 Buffer memory 21 Pixel counter 22 Microcomputer 23 Memory | storage part 29 Control part 30 Serial access type storage unit 31 AND circuit 32 Microcomputer for image processing 70 Area image sensor 71 Imaging lens 72 Light source 73 Prism mirror

Claims (15)

A position detection device for detecting an indicator located on a detection surface, the position detection device comprising:
An area image sensor in which photosensitive elements are two-dimensionally arranged, an imaging lens, and a light source that is disposed in the vicinity of the imaging lens and emits light along the detection surface. A pair of imaging units for imaging the detection surface with a visual field and outputting an image signal;
A retroreflective member that retroreflects light from the light source toward the imaging lens;
By the imaging unit, and a plurality of markers means criteria for defining a particular field of view of the position closer to the detection plane of the visual field and Do Ri, is provided at a predetermined position on the detection surface in the,
Any of pixels arranged linearly on a pixel array, pixels arranged diagonally, and pixels arranged with a refracted portion corresponding to the specific field of view defined with the marker means as a reference with the image signal as an input Selecting means for selecting the specific pixel from the photosensitive element;
Image processing is performed by inputting a specific image signal corresponding to one of the specific pixels selected by the selection means, such as pixels arranged linearly on the pixel array, pixels arranged diagonally, or pixels arranged with a refracted portion. Performing image processing means for calculating the coordinates of the indicated position on the detection surface indicated by the indicator;
If the pointer on the detection surface is not detected, automatically at predetermined intervals, to detect the variation of the position of the marker means, and tracking means for said selecting means reselects the specific pixel,
A position detection apparatus comprising: The position detection apparatus according to claim 1 , wherein the retroreflective member is provided on the indicator. The position detection apparatus according to claim 1 , wherein the retroreflective member is continuously provided on at least three sides of the detection surface. The position detection apparatus according to claim 3 , wherein the specific field of view corresponding to the specific pixel is an area including a part or all of an image of the retroreflective member. The position detection apparatus according to claim 1 , wherein the marker means is disposed at least at four locations on the detection surface. 6. The position detection apparatus according to claim 5 , wherein the marker means is a retroreflective member configured so that the reflected image has a characteristic shape. 6. The position detection apparatus according to claim 5 , wherein the marker means is a light emitting unit that emits light. 8. The position detection apparatus according to claim 7 , wherein the marker means is a light emitting unit configured so that a light emission image has a characteristic shape. The position detecting device according to claim 7 or claim 8, wherein the light emitting portion, position detecting device according to claim only emits light when defining said specific field of view. A position detecting apparatus according to any one of claims 1 to 9, further comprising a memory for storing pixel selection information on the particular pixels to be selected by said selecting means, said selecting means, said A position detection device that outputs a specific image signal corresponding to the specific pixel from the image signal picked up by the image pickup unit using the pixel selection information stored in a memory. The position detection device according to claim 10 , further comprising a buffer memory that temporarily stores the image signal captured by the imaging unit, wherein the selection unit stores the pixel selection information stored in the memory. And outputting the specific image signal corresponding to the specific pixel from the image signal stored in the buffer memory. 12. The position detection device according to claim 11 , wherein the memory is a serial access type memory, and the stored pixel selection information is read in synchronization with an input clock signal. Detection device. The position detecting device according to any one of claims 1 to 12, between the image processing means and said selecting means are connected by high-speed serial transfer interface, the image processing means is included in a personal computer A position detecting device characterized by that. The position detecting device according to any one of claims 1 to 13, wherein the image processing means is a microcomputer, the coordinates of the indicated position may be output via the interface, wherein the microcomputer has A position detection device characterized by the above. A position detecting apparatus according to any one of claims 1 to 14, further comprising a display device, wherein the detection surface is the feature that it is a transparent plate for protecting a display surface of the display device Position detector.

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