Patent Publication Number: US-2015060641-A1

Title: Optical touch device

Description:
FIELD OF THE INVENTION 
     The invention relates to a touch device, and more particularly to an optical touch device. 
     BACKGROUND OF THE INVENTION 
     Recently, touch technology is largely applied into several kinds of electronic devices such as personal computers, industrial computers, tablets, mobile phones or large-scale electronic whiteboards, etc. Each of the electronic devices has a touch panel for a user to send control messages to the electronic devices, or draw or write on the touch panel by using a finger or a touching pen. In order to identify what are the control messages at the points touched by the finger or the touching pen, respectively, it is important to correctly detect the locations of the touched points on the touch panels nowadays. 
     At present, the touch technology can be classified into a resistive touch technology, a capacitive touch technology, and an optical touch technology. The optical touch technology can be further classified into, for example, an optical scanning type and other types. In an optical scanning type touch device, two rotatable reflective mirrors are used to respectively reflect the laser light for scanning an object on the touch panel. Furthermore, the time point the light detecting element received the laser light reflected from the object is recorded to confirm the angle that the rotatable reflective mirror has been rotated, thereby defining the coordinate position of the object on the touch panel. 
     However, the intensity of the laser reflected by the object may overload to result in a judging error of the time point when the object to be detected is close to one of the light detecting devices, and thus the location of the object on the touch panel may not be correctly defined. On the other hand, a low power laser may solve the overloading problem, but the intensity of the laser reflected by the object may be insufficient when the object to be detected is far from one of the light detecting devices. Therefore, the judging error of the time point owing to one of the light detecting devices disturbed by the noise may cause the location of the object on the touch panel may not be correctly defined. 
     SUMMARY OF THE INVENTION 
     The invention provides an optical touch device for precisely sensing a location of an object. 
     According to an embodiment of the invention, an optical touch device defines a sensing area, and includes two scanning modules and a light detecting element. The two scanning modules are respectively disposed on two terminals of a first side of the sensing area. Each of the scanning modules includes a light-emitting element and a reflective element. Each of the light-emitting elements is used for emitting a detective light along a first pathway. Each of the reflective elements has a reflective surface for reflecting the detective light such that the detective light is emitted along a second pathway. There is an angle formed between the first side and the second pathway and the reflective surface is configured to be rotated in a determined angle range for changing a direction of the second pathway such that the detective light scans the sensing area, the determined angle range includes a first preset range and a second preset range, the detective light has a first intensity when a value of the angle is under the first preset range, and the detective light has a second intensity when the value of the angle is under the second preset range, in which the first intensity is less than the second intensity and any one value of the first preset range is less than any one value of the second preset range. The light detecting element is disposed beside the first side of the sensing area and located between the two scanning modules for receiving a reflected light reflected by an object located in the sensing area. 
     According to another embodiment disclosed herein, the optical touch device further includes a carrier board for carrying the scanning modules and the light detecting element. 
     According to another embodiment disclosed herein, the light-emitting element of the scanning module is located between a corresponding reflective surface and the light detecting element. 
     According to another embodiment disclosed herein, the optical touch device further includes a critical angle that divides the first preset range from the second preset range, and the critical angle is the largest angle formed between the first side and the detective light reflected by the reflective surface in the first preset range. 
     According to another embodiment disclosed herein, the determined angle range further includes a third preset range, and the detective light has a third intensity when the value of the angle is under the third preset range, the third intensity is less than the second intensity, and any one value of the second preset range is less than any one value of the third preset range. 
     According to another embodiment disclosed herein, a scanning speed of the detective light in the second preset range is larger than a scanning speed of the detective light in the third preset range. 
     According to another embodiment disclosed herein, each of the scanning modules further includes a light detector, each of the light detectors is disposed on a second side of the sensing area, and the second side is connected to the first side. 
     According to another embodiment disclosed herein, each of the scanning modules includes a base, and the light detectors, the reflective elements, and the light-emitting elements are respectively disposed on the bases. 
     According to another embodiment disclosed herein, the light detecting element is located between the bases. 
     According to another embodiment disclosed herein, each of the light-emitting elements is a power-adjustable light-emitting element for changing an intensity of the detective light. 
     The optical touch device of the invention can adjust the intensity of the detective light according to the range of the scanning area such that the light detecting element can receive the detective light having suitable intensity when the object is far from the light detecting element or close to the light detecting element. Thus, the optical touch device can correctly detect the location of the object, wherein the intensity of the reflected light received by the light detecting element corresponds to the intensity of the detective light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
         FIG. 1  illustrates a top view of an optical touch device according to an embodiment of the invention; 
         FIG. 2  illustrates a magnified drawing of an A part of the optical touch device shown in  FIG. 1 ; and 
         FIG. 3  illustrates a partial top view of an optical touch device according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the invention may be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
       FIG. 1  shows a top view of an optical touch device  100  according to an embodiment of the invention. As shown in  FIG. 1 , the optical touch device  100  defines a sensing area  101 , for example, the shape of the sensing area may be, but not limited to, rectangle, etc. The shape/location of the sensing area can be altered according to actual design requirement. The optical touch device includes two scanning modules  110  and a light detecting element  120 . When a detective light  112   a  emitted by the scanning modules  110  is reflected by an object  200  in the sensing area  101 , the detective light being reflected by the object  200  is defined as a reflected light  112   a ′ as shown in  FIG. 1 . The reflected light  112   a ′ will be received by the light detecting element  120 . In this embodiment, the optical touch device  100  further includes a carrier board  130  for carrying the scanning modules  110  and the light detecting element  120 . For example, the carrier board  130  may be, but not limited to, a display panel or a panel that does not have a display function (e.g., a glass panel, a plastic panel, etc.). Moreover, the object  200  may be, but not limited to, a finger of a user, a touch pen or any object able to reflect the detective light  112   a.    
     The two scanning modules  110  are respectively disposed on two terminals of a first side  101   a  of the sensing area  101 , in which the two terminals are opposite to each other. Each of the scanning modules  110  includes a light-emitting element  112  and a reflective element  114 . The light-emitting element  112  is used for emitting the detective light  112   a  along a first pathway d 1 , in which the first pathway d 1  may be parallel to the first side  101   a . In this embodiment, each of the light-emitting elements  112  is located between the light detecting element  120  and the reflective elements  114 . The light-emitting elements  112  is a power-adjustable light-emitting element for changing an intensity of the detective light  112   a , and how to change the intensity of the detective light  112   a  emitted by the light-emitting elements  112  should not be limited. In addition, the detective light  112   a  may be, but not limited to, a laser. Furthermore, the detective light  112   a  may be, but not limited to, an infrared laser. On the other hand, the reflective element  114  has a reflective surface  114   a  for reflecting the detective light  112   a  emitted by the light-emitting element  112  such that the detective light  112   a  is emitted along a second pathway d 2 . In this embodiment, the light-emitting elements  112  has an emitting surface, and the emitting surface faces to the reflective surface  114   a  such that the detective light  112   a  emitted by the light-emitting elements  112  may be transmitted to the reflective surface  114   a  along the first pathways d 1  and transmitted along one of the second pathways d 2  after being reflected by the reflective surfaces  114   a . There is an angle θ formed between the first side  101   a  and the second pathway d 2 . In addition, the reflective surface  114   a  is configured to be rotated in a determined angle range for changing a direction of the second pathway d 2  such that the detective light  112   a  scans the sensing area  101  along the different second pathway d 2 . In other words, the reflective surface  114   a  is rotated in the determined angle range such that the angle θ formed between the first side  101   a  and the second pathway d 2  may be changed. Thus, an emitted direction of the detective light  112   a  may be changed such that the detective light  112   a  scans the sensing area  101  in the determined angle range R. In this embodiment, the reflective element  114  may be, but not limited to, micro-electronic-mechanic system (MEMS) oscillatory reflectors. In an ideal embodiment, the reflective surface  114   a  may be rotated in the determined angle range R about 90° (may be shown as −45°˜45° such that the range of the angle θ formed between the first side  101   a  and the second pathway d 2  may be 0°˜90° such that the detective light  112   a  scans all sensing area  101  under the determined angle range R. In practice, the rotatable angle of the reflective surface  114   a  may not be exactly 90° because of several factors. In this case, adjusting the setting angle of the reflective surface  114   a  to fine-tune the angle θ can make the range of the angle θ formed between the first side  101   a  and the second pathway d 2  to be 0°˜90°. 
     In addition, each of the scanning modules  110  includes a light detector  116 , the light detector  116  is, but not limited to, disposed on a second side  101   b  of the sensing area  101 , in which the second side  101   b  is connected to the first side  101   a  and the second side  101   b  is perpendicular to the first side  101   a . However, the light detector  116  and the light-emitting element  112  may be, but not limited to, disposed on the second side  101   b  of the sensing area  101 . In another embodiment, the position of the light detector  116  and the light emitting element  112  are interchangeable. In this embodiment, the light detector  116  may, for example, detect the detective light  112   a  when the angle θ is 90°. Therefore, the angle variation value of the angle θ can be calculated by recording two time points that the light detector  116  continuously receives the detective light  112   a . Then, a database of the values of the angle θ in every time point can be constructed. Thus, the light detecting elements  120  can determine the angle variation value of the angle θ according to the database when the light detecting elements  120  detect the location of the object  200 . In detail, a formula showing the value of the angle θ is as follows: 
       θ=90−45*(1−COS(2π ft ))* A/ 90+ B  
 
     in which f is the frequency of the light detector  116  continuously receiving the detective light  112   a  for two times, t is the time the reflective face  114   a  being rotated, A is the angle range that the reflective surface  114   a  is actually rotated, and B is the tuning value of the disposing angle of the reflective surface  114   a.    
     It should be understood that the light detectors  116  may not be disposed when the rotating angle of the reflective element  114  has already been known. In this embodiment, each of the scanning modules  110  may, but not be limited to, include a base  118 , and the light detectors  116 , the reflective elements  114  and the light-emitting elements  112  are respectively disposed on the bases  118 , and light detecting elements  120  are connected between the bases  118 . 
       FIG. 2  shows a magnified drawing of a part of the optical touch device A shown in  FIG. 1 . As shown in  FIG. 1  and  FIG. 2 , the determined angle range R includes the first preset range r 1  and the second preset range r 2 . In this embodiment, the scanning module  110  of the optical touch device  100  further may, but be not limited to, include a critical angle θ 1  that divides the first preset range r 1  from the second preset range r 2 , in which a range of the critical angle is 10°˜15°. It should be understood that the critical angle θ 1  is the max value of the angle θ that is formed between the detecting light  112   a  reflected by the reflected surface  114   a  and the first side  101   a  in the first preset ranges r 1 . That is to say, when the detective light  112   a  reflected by reflective surface  114   a  scans under the first preset range r 1 , the light power of light-emitting element  112  can be adjusted so as to emit the detective light  112   a  having the second intensity. For example, when the light power of the light-emitting element  112  is, but not limited to, 45 mW, the light-emitting element  112  may emit the detective light  112   a  having the first intensity. On the other hand, the detective light  112   a  has a second intensity when the detective light  112   a  is reflected by reflective surface  114   a  such that a value of the angle θ is under the second preset range r 2 , in which the first intensity is less than the second intensity. That is to say, when the detective light  112   a  scans under the second preset range r 2 , the light power of light-emitting element  112  can be adjusted so as to emit the detective light  112   a  having the second intensity. For example, when the light power of the light-emitting element  112  is, but not limited to, 150 mW, the light-emitting element  112  may emit the detective light  112   a  having the second intensity. In this embodiment, a scan area formed by the detective light  112   a  scanning under the first preset range r 1  is closer to the light detector  120  than a scan area formed by the detective light  112   a  scanning under the second preset range r 2 . That is, the value of the angle θ under the first preset range r 1  is less than the value of the angle θ under the second preset range r 2 . In this embodiment, any one value of the first preset range r 1  is less than any one value of the second preset range r 2 . Accordingly, the value of angle θ formed by the detective light  112   a  reflected by the reflective surface  114   a  under the first preset range r 1  is less than the value of angle θ under the second preset range r 2 . Besides, the method of adjusting intensity of detective light  112   a  is not just for changing the power of the light emitting element  112 . In another embodiment, a light energy attenuator (not shown) may be disposed on the pathway of the detective light  112   a  under the first preset range r 1  such that the intensity of the detective light  112   a  under the first preset range r 1  is less than the intensity of the detective light  112   a  under the second preset range r 2 . 
     Referring to  FIG. 1  again, the light detecting element  120  of the optical touch device  100  is disposed beside the first side  101   a  of the sensing area  101  and located between the two scanning modules  110  for receiving the reflected light  112   a ′ reflected by the object  200  located in the sensing area  101 . In other words, when the object  200  is located on the sensing area  101  and the detective light  112   a  meets the object  200  along the second pathway d 2 , the detective light  112   a  will be scattered to form the reflected light  112   a ′. Then, the light detecting element  120  can receive part of the reflected light  112   a ′ toward the light detecting element  120 . Next, the time points of the reflected light  112   a ′ received are analyzed, and thus the value of the angle θ can be obtained. After the value of the angle θ is obtained, the optical touch device  100  may use the triangle localization method to calculate the location of the object, in which the optical touch device  100  may have an internal processing element to calculate the location of the object  200 . 
     In this embodiment, the optical touch device  100  may adjust the intensity of the detective light  112   a  according to the different preset ranges of the sensing area  101  such that the light detective elements  120  may receive the suitable intensity of the reflected light  112   a ′ to correctly detect the location of the object  200  when the object is close to the light detective element  120  or far from the light detective element  120 . In addition, the intensity of the detective light  112   a  can be changed by changing the light power of the light-emitting element  112  according to the time period because the time period of the detective light  112   a  is fixed in the first preset range r 1  and the second preset range r 2 . 
       FIG. 3  shows a partial top view of an optical touch device  100 ′ according to another embodiment of the invention. As shown in  FIG. 3 , the optical touch device  100 ′ is similar to the optical touch device  100  shown in  FIG. 1 , but the difference is the determined angle R in this embodiment includes a first preset range r 1 , a second preset range r 2 , and a third preset range r 3 , in which any one value of the second preset range r 2  is less than any one value of the third preset range r 3 . Accordingly, the value of angle θ formed by the detective light  112   a  reflected by the reflective surface  114   a  under the second preset range r 2  is less than the value of angle θ under the third preset range r 3 . In this embodiment, a scan area formed by the detective light  112   a  scanning under the third preset range r 3  is closer to the light detector  120  than a scan area formed by the detective light  112   a  scanning under the second preset range r 2 . When the reflective surface  114  is rotated to a max angle (e.g. +45° or −45°, the reflective surface  114   a  will then be rotated to a reverse direction, and thus the rotating speed of the reflective surface  114   a  will become slow and so the scanning speed of the detective light  112  will become slow. The third preset range r 3  is the range that the scanning speed of the detective light  112   a  becomes slow. That is, the scanning speed of the detective light  112   a  under the second preset range r 2  is larger than the scanning speed of the detective light  112   a  under the third preset range r 3 . The reflected light  112   a ′ may stay on the same position of the light detecting element  120  (referring to  FIG. 1 ) for a longer time because the scanning speed becomes slow, the light detecting element  120  may receive more energy. In order to meet the safety requirement, the detective light  112   a  has a third intensity, in which the third intensity is less than the second intensity when the value of the angle θ is under the third preset range r 3 . In this embodiment, the third preset range r 3  is 80°˜90°. In other words, when the angle θ is 80°˜90°, the detective light  112   a  has the third intensity that is, but not limited to, less than the second intensity. The third intensity can be equal to the first intensity, or can be larger or less than the first intensity. In addition, the way of adjusting the intensity of the detecting light  112   a  is similar to the foregoing and will not be further described. 
     The optical touch device can adjust the intensity of the detective light according to the range of the scanning area such that the light detecting element can receive the detective light having suitable intensity when the object is far from the light detecting element or close to the light detecting element, and thus the optical touch device can correctly detect the location of the object. In addition, the power of the detective light can be decreased such that the optical touch device meets the safety requirement in the range that the reflective surface is rotated slowly. 
     The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. Moreover, these claims may refer to use “first”, “second”, etc. following with noun or element. Such terms should be understood as a nomenclature and should not be construed as giving the limitation on the number of the elements modified by such nomenclature unless specific number has been given. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the invention as defined by the following claims. Moreover, no element and component in the disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.