Abstract:
An optical module for an optical mouse utilizes the optical theory to provide the light signals as coordinates enabling the optical mouse to offer smoother response and precise tracking. The light coming from a light-emitting device forms the image through multiple transmissions, refractions and reflections, and the image reflects on a light signal acquisition device to provides the coordinates for the displacement of the optical mouse.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    I. Field of the Invention 
         [0002]    An optical module that is applied to the optical mouse is designed to acquire the light signals that form the image. The present invention refers especially to an optical module that can collimate light from the light source into reflective light by refraction and reflection so as to assure the optical mouse of smooth response and precise tracking on almost any transparent and even surface. The optical mouse with the optical module of the present invention become easier to operate and offers user-friendly convenience. 
         [0003]    II. Description of the Prior Art 
         [0004]    Because of employing the optical module as the interface to retrieve the image by the coordinates, the optical mouse can be built to be lightweight and have a compact size to offer a smoother response and precise tracking on almost any surface. They thus eventually replaced the mechanical trackball mouse. The optical mouse usually utilizes two encoder sets that output the serial logical signals to perform the logic operation of X-axis and Y-axis for displacement on the contact surface. 
         [0005]    With reference to  FIG. 1 , which is a sectional view of an optical module of the prior art, the optical module  10  mainly comprises a 1 st  lens  101 , a 1 st  reflecting portion  102 , a 2 nd  reflecting portion  103 , a refracting portion  104  and a 2 nd  lens  105 . It also comprises a light-emitting device  106 , which is installed near the 1 st  lens  101  and serves as the light source, and an image retrieval device  107 , which is installed above the 2 nd  lens  105 . In terms of the light source, the light emitting diode (LED) is the most adopted one among various light-emitting devices. This optical module  10  projects the LED light on the image capture facet A for retrieving a clear image to drive the displacement of an optical mouse. The light-emitting device  106  emits the light source light F that produce the light beam. The refractions and reflections of the light source light F are also shown in  FIG. 1 : the light source light F enters the 1 st  lens  101  for being projected on the 1 st  reflecting portion  102  and transferred into the 1 st  reflected light beam F 1 ; the 1 st  reflected light beam F 1  is projected on the 2 nd  reflecting portion  103  and transferred into the 2 nd  reflected light beam F 2 ; the 2 nd  reflected light beam F 2  enters the refracting portion  104  and transfers into the refractive light beam F 3 ; the refractive light beam F 3  is projected onto an image capture facet A, which may be the surface of a desk on which an optical mouse is placed, to form an irradiation area F 4 . When the irradiation area F 4  covers the image capture facet A, the latter is illuminated to a level that facilitates the image retrieval: the image capture facet A must be of rugged surface (see the enlarged portion of  FIG. 1 ), and the irradiation area F 4  is to receive the light source light at an included angle of 20˜35 degrees; the light source light is blocked by the concavity A 1  on the rugged surface causing the umbra A 11 ; the image retrieval device  107  retrieves the image composed of umbra A 11  via the 2 nd  lens  105 . The said image retrieval also relates to logic operations by the electronic components. And, this is how the user can move the cursor with an optical mouse to latch onto an icon on the screen and click it to execute a function. This optical module  10  mainly utilizes the refraction and reflection to change the direction of the LED light so as to form an irradiation area F 4  covering an image capture facet A of rugged surface where the light is blocked by the concavity A 1  causing the umbra A 11 . The image composed of umbra A 11  serves as the base of the logic operations. The image retrieval device  107  succeeds in retrieving the image composed of umbra A 11  (see the mesh graph B of light signals in  FIG. 1 ) as the lightness of the irradiation area F 4  contrasts sharply to the umbra. According to  FIG. 1 , the image capture facet A is actually a surface where the user operates the mouse. Should it be the smooth surface of a glass or acrylic, there would be no concavity A 1  causing the umbra A 11  nor image composed of umbra A 11 . Under such circumstances, the image retrieval device  107  would fail to retrieve the image as there would be no contrast of the umbra A 11  to the lightness of the irradiation area. Consequently, the user would fail to move the cursor with an optical mouse to latch onto an icon on the screen and click it to execute a function. It is thus understood that the optical mouse with this optical module  10  cannot be utilized on a smooth surface. 
         [0006]    The “Optical Image Retrieval Method” of Taiwan Patent No. 1230359 refers to another application of the optical module of the prior art where an image sensor retrieves the image through refractions and reflections by a spectroscope: the light-emitting device emits in the vertical direction a light axis that enters a transparent media to reach an image contact surface, which is beneath  the transparent media; and, the image formed on the image contact surface is projected to a spectroscope for multiple refractions so as to assure the optimum image retrieval. This application focuses on reducing the phase error as it employs a spectroscope for the light axis to refract at one single spot between the light-emitting device and the image sensor. 
       SUMMARY OF THE INVENTION 
       [0007]    The main objective of the present invention is to provide an optical module that assures the optical mouse of smoother response and precise tracking on almost any smooth surface. 
         [0008]    The optical module of the present invention is a miniature one-piece module that can be installed in an optical mouse. It comprises several lenses, several reflecting portions and a spectroscope, and functions with a light-emitting device and a light signal acquisition device. The light from a light source transmits and refracts to transfer into a vertical coaxial light beam that is projected to an image capture facet where the uneven surface causes different reflections forming the light signals (beam spots). The light signals acquisition device  acquires the light signals while they refracted at a lens. Even the smooth surface of glass has invisible pores causing different reflections to form the light signals that can be received by a light signal requisition device. Therefore, the optical module of the present invention can assure the optical mouse of smoother response and precise tracking on a transparent and smooth surface. 
         [0009]    Desirable features of the present invention will be better understood from the detailed description and drawings that follow, in which various embodiments of the disclosed invention are illustrated by way of example. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  is a sectional view of the optical mouse of a prior art. 
           [0011]      FIG. 2  is a sectional view of the optical module of the present invention. 
           [0012]      FIG. 3  is a sectional view showing how the optical module of the present invention forms an image by the light signals. 
           [0013]      FIG. 4  shows a preferred embodiment of the present invention. 
           [0014]      FIG. 5  shows the optical module of the present invention installed in an optical mouse.  
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    With reference to  FIG. 2 , which is a sectional view of the optical module  20  of the present invention, the optical module  20  comprises a 1 st  condensing lens  201 , a 1 st  reflecting portion  202 , a 2 nd  reflecting portion  203 , a 2 nd  condensing lens  204 , a spectroscope  205  and a lens  206 . This optical module  20  is to provide light from a light source (not illustrated in  FIG. 2 ) that transmits, refracts and reflects. As shown in  FIG. 2 : the 1 st  reflecting portion  202  tilts against the 1 st  condensing lens  201  at a proper angle and distance so that the light source light can reflect at the 1 st  reflecting portion  202  after it enters and leaves the 1 st  condensing lens  201 ; the 2 nd  reflecting portion  203  and the 1 st  reflecting portion  202  are formed with a proper interval that the light source light from the 1 st  reflecting portion  202  reflects at the 2 nd  reflecting portion  203 ; the 2 nd  condensing lens  204  and the 2 nd  reflecting portion are formed at a proper included angle that the light source light from the 2 nd  reflecting portion  203  can be collimated by the  2 nd condensing lens  204  into a thin beam of parallel rays; the spectroscope  205  and the 2 nd  condensing lens  204  are formed with a proper interval that the beam of parallel rays transferred by the 2 nd  condensing lens  204  can reflect at the image capture facet A. 
         [0016]    With reference to  FIG. 3 , which shows how the optical module of the present invention transfers the light signal into an image, it is a light-emitting device  207  (e.g. a light emitting diode with wavelength of 680 nm˜950 nm or a laser diode) that emits the light source light f through orthogonal or side projection. The path of the light source light f is as follows: the light source light f shall converge on the 1 st  condensing lens  201  into a 1 St  parallel light beam f 1  that travels to the 1 st  reflecting portion  202  and reflects a 1 st  reflected light f 2  thereat; the 1 st  refractive light f 2  shall travel to the 2 nd  reflecting portion  203  and reflects a 2 nd  reflecting light beam f 3  thereat; the  2 nd reflecting light beam f 3  travels to the 2 nd  condensing lens  204  where it is collimated into a thinner light beam, the 2 nd  parallel light beam f 4 . Furthermore, the 2 nd  parallel light beam f 4  immediately projects to the spectroscope  205  where it reflects at 80˜90 degrees and transfers into a 3 rd  refractive light f 5 . The 3 rd  refractive light f 5  reflects at the image capture facet a and transfers into a reflective light beam f 6 . Under the circumstances, the beam spots (as shown in the mesh graph of  FIG. 2 ) are formed and pass through the lens  206  that the light signal acquisition device  208  can acquire them in whole. It is also shown in  FIG. 2  that the design of the 1 st  condensing lens  201 , 1 st  reflecting portion  202 , 2 nd  reflecting portion  203  and 2 nd  condensing lens allows the light source f converging into a thin light beam (the 1 st  refracting light f 1 , the  2 nd reflecting light f 2 ). The 2 nd  condensing lens  204  collimates the thin light beam into a parallel light beam f 4  that can be transferred by the spectroscope into vertically downward reflected light (the 3 rd  refractive light f 5  and the reflective light beam f 6 ). The beam spots are thus formed. With reference to the enlarged portion of  FIG. 3 , the 3 rd  refractive light f 5 , reflective light beam f 6 , lens  206 , light signal acquisition device  208  and mage capture facet a are in coaxial vertical alignment. And, in order to gather the light beam for projection, the image capture facet a has uneven surface that produces different reflections to form the beam spots. With the lens  206 , the light signal acquisition device  208  can effectively receive any beam spots (which form the image) whether the image capture surface A is smooth or uneven. In other words, the mouse with the optical module of the present invention can retrieve the image from the surface of any materials. 
         [0017]    With reference to  FIG. 4 , which shows a preferred embodiment of the present invention, the lens  206  is a separate part installed in a holding portion  209  formed on the top of the optical module  20 . The design of the holding portion  209  not only allows the optical module  20  to accommodate different lenses to meet any requirements, but also drastically reduces the molding cost and elevates the production effectiveness. 
         [0018]    With reference  FIG. 5 , the optical module  20  of the present invention is installed in a mouse  30  as a position feedback system. 
         [0019]    It is understood from the foregoing description that the present invention is an integral unit of lens, refracting lens and spectroscope where light from a light source can transfer into coaxial refractive and reflective lights by refraction and reflection. This integral unit allows the light signals vertically reflecting in the same axial direction that allows the light signal acquisition device to acquire them in whole. Under the circumstances, the beam spots can always form the image whether the image capture surface is transparent and smooth or not. Consequently, the optical mouse that has the optical module of the invention offers incredibly smooth, precise tracking. 
         [0020]    To sum up, the present invention achieves successfully to provide an optical module that assures the optical mouse of smoother response and precise tracking on a transparent, smooth surface. 
         [0021]    New characteristics and advantages of the present invention covered by this document have been set forth in the foregoing description. Understanding is sought however, that the drawings are for the purpose of illustration only and not intended to be a definition of the limits of the present invention. Changes in methods, shapes, structures or devices may be made in details without exceeding the scope of the invention by those who are skilled and knowledgeable in the field.