Abstract:
Disclosed herein is a pen-type optical pointing device. The pen-type optical pointing device detects the moving direction and distance thereof in such a way as to radiate light onto a plane, detect an image of the plane and analyze the difference between a previous image and a current image. The pen-type optical pointing device includes a casing configured for a lower portion thereof to converge toward a central axis thereof, with an opening being provided at a lower end thereof; and an illumination device installed inside the casing, near the opening of the casing and on an acutely inclined side of the casing to have an illumination angle ranging from 15° to 60°. If the pen-type pointing device constructed as described above is employed, the lower-end portion thereof can be reduced while an illumination angle used in existing optical mice can be maintained, so that it is possible to provide a pen-type pointing device having the same size as an existing writing pen.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a pen-type optical pointing device.  
         [0003]     2. Description of the Related Art  
         [0004]     Generally, a variety of optical pointing devices, including a pen-type mouse, detect the moving distances and directions thereof in such a way as to illuminate surfaces using Light Emitting Diodes (LEDs), receive the shapes of the surfaces through lenses in the form of images, and process the images.  
         [0005]     In the case where LED illumination light is radiated onto white surfaces or objects having minutely rough surfaces at an angle of about 20°, shadows of the minutely rough surfaces are generated, so that the precise movement of the pointing devices can be detected using more clearly distinguishable image patterns. Accordingly, when light radiated onto the surfaces forms an angle of about 20° with respect to the surfaces, the images of the surfaces input to the optical pointing devices are optimized, so that the optical pointing devices have optimum sensitivity.  
         [0006]     Meanwhile, in a conventional pen-type mouse using a tip point  140  (having a diameter of about 1.5 cm) as shown in  FIG. 1A , the angle  142  between the illumination direction of an illumination LED  141  and a vertical axis is too small to achieve an optimum illumination angle of 20° with respect to a surface in consideration of the fact that the pen-type mouse is generally used while held inclined at an angle ranging from about 30° to about 40°. Furthermore, in the case where the pen-type mouse is used in an almost vertical position, like the case where the pen-type mouse is used on the palm instead of on a surface, the illumination angle becomes excessively large, thus considerably degrading the sensitivity of the pen-type mouse.  
         [0007]     In order to solve the above-described problems, by widening the angle  143  to an angle of about 35° as shown in  FIG. 1B , the illumination angle of the LED with respect to the surface is 20°, that is, the optimum angle, in the case where the pen-type mouse is used while generally remaining inclined at an angle within a range from 30° to 40°. Even when the pen-type mouse is used in a vertical position, a somewhat sufficient illumination angle can be ensured. however, in this case, the pen-type mouse must be thick as illustrated well in  FIG. 1B , so that it is inconvenient to use the pen-type mouse.  
         [0008]     Furthermore,  FIGS. 2A and 2B  illustrate variation  155  in the distance between a surface (detection region) and the optical mouse sensor when the conventional pen-type mouse equipped with the tip point is used in an inclined position. Reference numeral  151  designates an optical mouse sensor, reference numeral  152  designates an optical lens, reference numeral  153  designates the distance between the central axis of the path of an optical image and the central axis of the tip point, and reference numeral  156  designates the angle between the central axis and the surface. If it is assumed that the inclined angle of the pen-type mouse is 25° and the distance  153  is about 1.5 mm in terms of mechanism design, the difference  155  in distance, that is, 1.5 mm×tan 25°=0.7 mm, becomes considerably long, so that the distortion of an image input through the lens  152  is high, thus degrading the pointing sensitivity of the pen-type mouse.  
         [0009]     The conventional pen-type mouse using the tip point is disadvantageous in that the amount of light is reduced in proportion to the length of the tip point.  
         [0010]     In order to overcome the disadvantages of the above-described conventional pen-type mouse, in another conventional pen-type mouse, an optical guide is mounted at a location where the tip point is mounted on the first conventional pen-type mouse, as shown in  FIGS. 3A and 3B . Reference numeral  180  of  FIG. 3A  designates the path of light around the lower end of the optical guide, and  FIG. 3B  illustrates an illumination angle  181  when the pen-type mouse is inclined at an angle of 25° during use.  
         [0011]     In this conventional pen-type mouse, it is possible to use the pen-type mouse at an optimum illumination angle when the pen-type mouse is used while held inclined, as shown in  FIG. 3A . However, when the pen-type mouse is used in a vertical position, the illumination angle of light becomes almost parallel to the surface, so that the sensitivity of the pen-type mouse is extremely degraded. Accordingly, the structure of  FIG. 3  is disadvantageous in that the sensitivity of a pointing operation may be considerably degraded depending on the angle at which the pen-type mouse is inclined during use. The case where a chip LED, instead of the optical guide, is mounted on the side of the tip point is the same.  
       SUMMARY OF THE INVENTION  
       [0012]     Accordingly, the present invention has been made keeping in mind the above problems of the conventional pen-type pointing device, and an object of the present invention is to provide a pen-type pointing device that has low variation in sensitivity despite variation in use angles and can achieve optimum sensitivity at normal use angles while keeping the thickness of the pen-type pointing device small.  
         [0013]     In order to accomplish the above object, the present invention provides a pen-type optical pointing device, the pen-type optical pointing device detecting a moving direction and distance thereof in such a way as to radiate light onto a plane, detect the image of the plane and analyze the difference between a previous image and a current image, including a casing configured for the lower portion thereof to converge toward the central axis thereof, with an opening being provided at the lower end thereof; and an illumination device installed inside the casing, near the opening of the casing and on an acutely inclined side of the casing to have an illumination angle ranging from 15° to 60°.  
         [0014]     Additionally, the present invention provides a pen-type optical pointing device, the pen-type optical pointing device detecting a moving direction and distance thereof in such a way as to radiate light onto a plane, detect the image of the plane and analyze a difference between a previous image and a current image, including a casing configured for the lower portion thereof to gradually converge toward the central axis thereof, with an opening being provided at the lower end thereof; and a tip point configured to protrude through a portion of the opening located on a side opposite to a side toward which the pen-type pointing device is inclined, come into contact with the plane at the bottom thereof, and radiate illumination light in a direction opposite to a direction in which the pen-type pointing device is inclined.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0016]      FIGS. 1A and 1B  are diagrams schematically illustrating a conventional pen-type mouse;  
         [0017]      FIGS. 2A and 2B  are diagrams schematically illustrating the conventional pen-type mouse of  FIG. 1  in an inclined position;  
         [0018]      FIGS. 3A and 3B  are diagrams schematically illustrating another conventional pen-type mouse;  
         [0019]      FIGS. 4A and 4B  are diagrams schematically illustrating a pen-type mouse according to a first embodiment of the present invention;  
         [0020]      FIGS. 5A and 5B  are diagrams schematically illustrating a pen-type mouse according to a second embodiment of the present invention;  
         [0021]      FIGS. 6A  to  6 C are diagrams schematically illustrating a pen-type mouse according to a third embodiment of the present invention;  
         [0022]      FIGS. 7A and 7B  are diagrams illustrating the mounting of the pen-type mouse of the present invention on a mobile terminal and the use of the mobile terminal equipped with the pen-type mouse; and  
         [0023]      FIG. 8  is a system configuration diagram of a mobile terminal to which the pen-type mouse of the present invention is applied. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     With reference to  FIGS. 4A and 4B , a first embodiment of the present invention is described in detail below.  
         [0025]     Reference numeral  110  designates the casing of a pen-type mouse, the outer diameter  115  of which is 7.4 mm and the inner diameter  114  of which is 6 mm, so that it can be understood that the size of the pen-type mouse is considerably reduced compared to that of the conventional pen-type mouse (having an output diameter in a range from 17 mm to 21 mm). An optical mouse sensor  111  is formed by attaching a semiconductor wafer-shaped optical mouse sensor on a thin flexible Printed Circuit Board (PCB). Reference numeral  112  designates an optical lens and reference numeral  113  designates a chip LED having a thickness of 0.6 mm.  
         [0026]     In the embodiment of  FIG. 4A , the angle  120  between the longitudinal axis of the pen-type mouse and the illumination direction of the chip LED  113  is about 35°, so that the angle between the illumination direction of the chip LED  113  and the horizontal axis of the surface is about 55° (90°-35°) Therefore, even in the case where the pen-type mouse is almost vertically used, a somewhat desirable illumination angle with respect to the surface (horizontal surface) can be ensured.  
         [0027]      FIG. 4B  illustrates an example of an illumination angle in the case where the pen-type mouse is used while remaining inclined. The inclined angle  122  at which the pen-type mouse is used is generally 25°˜40°. In this case, the illumination angle  122  of the chip LED  113  with respect to the horizontal axis of the surface is calculated to be 30°˜50° using the equation (90′-angle  120 -angle  121 ), thus implementing an illumination angle of about 20° that is the optimum angle used in general optical mouse.  
         [0028]     Meanwhile, in regard to the implementation of the mechanism of the pen-type mouse, it is possible to implement the pen-type mouse so that the angle between the vertical axis of the mechanism and the illumination axis of the LED  113  is in an angular range from 15° to 60°. However, an angle greater than 50° is not desirable in terms of the design of the lower end of the mechanism. Furthermore, when the sensitivity of the pen-type mouse depending on the angle and the design of the lower end of the mechanism are taken into account, the angle  120  is desirably within an angular range from 30° to 50°.  
         [0029]     In the first embodiment of the present invention shown in  FIGS. 4A and 4B , the end portion of the pen-type mouse is open, so that impurities, such as dust, can enter into the pen-type mouse and the pen-type mouse may not move smoothly along a rough surface and may be caught by the rough surface when the pen-type mouse is brought into contact with and moves along the rough surface. In order to overcome the above-described shortcomings, a round lower-end cover  130  made of transparent material (transparent plastic or transparent glass) is attached to the lower end of a pen-type mouse in the second embodiment of the present invention. The lower-end cover  130  directly comes into contact with a surface or a pointing detection region, and allows the pen-type mouse to smoothly slide along a contact surface regardless of the inclined position of the pen-type mouse during a pointing operation because it is made of transparent material and is formed in a round shape.  
         [0030]     Furthermore, as has been described in conjunction with  FIGS. 2A and 2B , in the prior art, the distance between the surface or pointing detection region and an optical image varies considerably depending upon the inclination angle of the pen-type mouse when the pen-type mouse is used, thus causing the degradation of sensitivity of the pen-type mouse. In the embodiment of the present invention shown in  FIGS. 5A and 5B , if it is assumed that the lower-end cover  130  has a diameter of 4 mm (a radius of 2 mm) and the inclined angle of the pen-type mouse is 25° when the pen-type mouse is used, the variation in distance  131  is 2 mm/cosine(25°)−2 mm=0.21 mm, which is considerably less than that (0.7 mm) of the prior art. Accordingly, when the pen-type mouse shown in  FIGS. 5A and 5B  is used, more stable pointing sensitivity can be ensured regardless of the inclined angle of the pen-type mouse that is formed during use.  
         [0031]     In the meantime, even though the lower-end cover  130  made of round, transparent material causes slight distortion such that the size of the image of a detection region is reduced, it does not influence general pointing work. When needed, the distortion can be compensated for by adjusting the displacement data output from the optical mouse sensor. The lower-end cover may be designed to have a function of compensating for a distorted image by making the curvatures of the inside and outside of the lower-end cover somewhat different from each other. Furthermore, the distortion is considerably less than the distortion of a detection region that occurs when the general pen-type mouse (see  FIGS. 2A and 2B ) is used while held inclined. A precise pointing function can be implemented by adjusting the ratio of displacement data at the time of compensating for the distortion.  
         [0032]     Furthermore, in the embodiments shown in  FIGS. 4 and 5 , the distance between the pointing detection region of a surface and an illumination device is reduced compared to the conventional pen-type mouse using a tip point, so that it is possible to use a chip LED the amount of light of which is less than that of the LED used in the conventional pen-type mouse, thus minimizing the lower end of the pen-type mouse of the present invention. Instead of using the LED, the present invention may use a slender optical guide (a slender tube the inside of which is coated with reflective material that reflects light) so as to allow light to be radiated from the lower end of the pen-type mouse of the present invention.  
         [0033]     Now, a third embodiment of the present invention is described with reference to  FIGS. 6A  to  6 C.  
         [0034]      FIGS. 6A  to  6 C illustrate a pen-type mouse, in which an optical guide, which transfers the light of an LED, is mounted at the lower end of the pen-type mouse, is used while being in contact with a surface, and functions as a tip point. Reference numeral  160  designates the external casing of the pen-type mouse, reference numeral  161  designates an optical image sensor, reference numeral  163  designates an LED, and reference numeral  164  designates an optical guide. The optical guide  164  is designed such that the upper end thereof has a round lens feature so as to make light entering from the LED linear and the lower end thereof is coated so as to function as a reflective mirror  166  and, therefore, reflect light at a predetermined angle. Reference numeral  165  designates an example of a light path through which light is transferred, and reference numeral  167  designates the inclined angle of the reflective mirror  166  that is formed at the lower end of the optical guide  164 . Reference numeral  168  designates the inclined angle of the pen-type mouse when the pen-type mouse is used, and reference numeral  169  designates the angle of illumination that is radiated onto a surface or detection region.  
         [0035]      FIG. 6C  is an enlarged view of the low end portion of the optical guide  164 . Reference numeral  170  designates the path of the light of the LED entering into the optical guide  164 , reference numeral  171  designates light reflected by the reflective mirror  166  and radiated onto a surface, and reference numeral  172  designates the angle between the central axis of the optical guide  164  and the reflective surface of the reflective mirror  166 . The angle  172  between the reflective mirror  166  and the central axis of the optical guide  164  that allows the pen-type mouse to be inclined at an angle of 25° during use and causes the angle  171  of the light radiated onto a surface to be an optimum angle, that is, 20°, is 90°−((angle  171 +angle  168 +90°)/2)=22.5°. When the angle  172  of the reflective mirror is in a range from 30° to 15° in the case where the inclined angle  168  of the pen-type mouse during use is in a range from 10°to 40°, illumination light can be radiated onto a detection surface at an angle of about 20°.  
         [0036]     Meanwhile, as can be understood from  FIG. 6A , even in the case where the pen-type pointing device is used in a vertical position, an illumination angle is ensured to some degree, so that the sensitivity of the pen-type mouse is not degraded.  
         [0037]     Furthermore, in order to reduce the size of the pointing device, a method of attaching a chip LED into an element having a tip point function instead of using the optical guide of  FIGS. 6A  to  6 C may be employed. In order to achieve the above-described illumination angle, the chip LED is mounted such that the angle between the chip LED and the central line of the tip point is in a range from 15° to 60°.  
         [0038]     In the meantime, although in the above-described embodiments, the chip LED or optical guide is employed, it can be readily understood that it is possible to employ optical fiber instead of them.  
         [0039]     Now,  FIGS. 7A and 7B  illustrate an example in which the pen-type mouse proposed in the present invention is applied to a mobile terminal.  
         [0040]     Referring to  FIG. 7A , a pointing device  211  is connected to a hinge  210 , which forms a folding structure. In the case of a recently marketed mobile terminal, an antenna does not protrude from a main body but is contained inside the main body. In this case, the pointing device  211  may not be folded.  
         [0041]      FIG. 7B  illustrates an example in which the initial characters of a name are written using the pointing device  211 , the name is recognized, and a telephone number corresponding to the name stored in the mobile terminal is dialed. Of course, it is possible to allow a full name to be written and recognize the full name.  
         [0042]     Furthermore, the pointing device of the present invention may be used as a pointing device with which to select a functional icon in such a way as to locate a cursor indicating a pointing position at the functional icon shown on the display of a mobile terminal, and press the pointing device using a predetermined amount of force or activate the functional icon using other button devices. Furthermore, the pointing device of the present invention may be used as a pointing device for an arcade game played on a mobile terminal. Therefore, the range of application of the pointing device of the present invention is very wide.  
         [0043]      FIG. 8  is a system block diagram of a mobile terminal equipped with the pointing device according to the present invention. Reference numeral  210  designates an input unit that is composed of the pointing device of the present invention that is attached to the mobile terminal. The input unit  210  transfers pointing data, including x and y displacement data in lateral and transverse directions, to a control unit  220 . Reference numeral  220  designates the control unit, including the Central Processing Unit (CPU) of the mobile terminal. The control unit  220  processes data so as to recognize written characters using pointing data input from the input unit  210 , utilize a cursor indicating a location on a screen as moving data, or have a pointing function on the game of the mobile terminal. A data storage unit  230  stores data that are required to put the pointing data into application. Reference numeral  240  designates a button input unit that relates to a variety of operational buttons arranged on the surface of the mobile terminal. The pressing of buttons is converted into information and is then transferred to the control unit  220 . Reference numeral  250  designates an output unit, including a display that recognizes input characters and displays the input characters. Reference numeral  260  designates a communication unit that receives and transmits data to perform the original functions of the mobile terminal. Reference numeral  270  designates some other unit, including an interface that can connect with a digital camera and external devices.  
         [0044]     If the pen-type pointing device constructed as described above is employed, the lower-end portion thereof can be reduced while an illumination angle used in existing optical mice can be maintained, so that it is possible to provide a pen-type pointing device having the same size as an existing writing pen.  
         [0045]     Furthermore, the present invention minimizes the distance between a pointing detection region and an illumination light without using a tip point at the lower end of the pen-type pointing device, so that it is possible to provide a pen-type pointing device having superior pointing sensitivity.  
         [0046]     Furthermore, a round, transparent element is mounted on the lower end of the pointing device that comes into contact with a surface when the pen-type pointing device operates, so that a smooth feeling can be experienced when using the pen-type pointing device of the present invention compared to when using the conventional pen-type pointing device having a tip point and so that the infiltration of dust and impurities into the pen-type pointing device can be prevented.  
         [0047]     Furthermore, the optical guide is constructed to have functions of illumination transfer and tip pointing, so that an inclined illumination angle of about 20° is established with respect to a detection region (the bottom of the device, the surface, etc.) and, thus, it is possible to provide a pointing device having superior pointing sensitivity.  
         [0048]     Additionally, it is possible to provide a method of maximizing the efficiency of use of light by minimizing the distance between a pointing detection region and an illumination device without using a tip point.  
         [0049]     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.