Abstract:
An imaging device may have an imaging surface and a sensor. The imaging surface may be illuminated by a first source and reflect at least some of the illumination to the sensor to detect an image. The imaging device may have a predetermined width and an optical path passing therethrough. The imaging device may be illuminated by a second source, and the illumination of the second source may be directed to one or more predetermined regions on or near the imaging surface to produce an optical effect associated with the imaging surface.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure relates to improvements in or relating to optical navigation devices. 
       BACKGROUND OF THE INVENTION 
       [0002]    Computer devices are becoming ever smaller, and full computing functionality can be found on phones and smart phones and other personal digital assistants (PDA). As computer devices become smaller, the various features of the computer devices may also become smaller. This may include smaller input systems for the user to enter data into the device. One such input system is an optical navigation device. Many computer devices, large and small, are equipped with optical navigation devices. However, with the smaller computer devices, minimizing the size of the optical navigation device can often be restrictive and problematic. 
         [0003]    A number of devices have been disclosed that offer thin thickness optical navigation devices. These have had some success, but the designs have generally not addresses some problems associated with thin imaging devices. One problem which may remain is providing custom shaped illumination on optical devices, such as a finger-mouse without having to resort to expensive or bulky options. Custom shaped illumination includes aesthetic and optical effects on the surface of the mouse which can have different uses. Previously, lightpipes have been disclosed as a way of custom shaping illumination. However, such lightpipes may require a lot of space, typically several millimeters, which would not be suitable for thin optical devices. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present disclosure to provide an approach to at least some of the problems associated with the prior art. It is a further object of the present disclosure to provide an optical navigation device having custom shaped illumination which does not add bulk or excessive cost to the manufacture of the optical navigation device. 
         [0005]    According to one aspect of the present disclosure, an imaging device may include an imaging surface and a sensor. The imaging surface may be illuminated by a first source and reflect at least some of the illumination to the sensor to detect an image. The imaging device may have a predetermined width and an optical path passing therethrough. The imaging device may be illuminated by a second source, and the illumination of the second source may be directed to one or more predetermined regions on or near the imaging surface to produce an optical effect associated with the imaging surface. 
         [0006]    The present embodiments may offer a number of benefits. The present embodiments may provide a predetermined region on the surface of the element which can be used to show optical and aesthetic effects. These effects can be design related or of practical use. The effects may be brought about by forming an optical element in a particular manner. The form may ensure that the device remains thin and does not cost much to implement. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Reference may now be made, by way of example, to the accompanying drawings, in which: 
           [0008]      FIG. 1   a  is a cross-sectional diagram of an imaging device for an optical navigation device, according to the prior art; 
           [0009]      FIG. 1   b  is a view of the top surface of the device of  FIG. 1   a;    
           [0010]      FIG. 2  is a cross-sectional view of one imaging element for an optical navigation device, according to the present disclosure; 
           [0011]      FIG. 3  is a cross-sectional view of another embodiment of an imaging element for an optical navigation device, according to the present disclosure; 
           [0012]      FIG. 4   a  is a cross-sectional diagram of an imaging device for an optical navigation device, according to the present disclosure; 
           [0013]      FIG. 4   b  is a top view of the device of  FIG. 4   a;    
           [0014]      FIG. 5   a  is a cross-sectional diagram of an imaging device for an optical navigation device, according to the present disclosure; 
           [0015]      FIG. 5   b  is a top view of the device of  FIG. 5   a;    
           [0016]      FIG. 6   a  is a cross-sectional diagram of an imaging device for an optical navigation device, according to the present disclosure; and 
           [0017]      FIG. 6   b  is a top view of the device of  FIG. 6   a.    
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present embodiments relate to an imaging device associated with an optical navigation device. The optical navigation device is a mouse of small-scale which is intended to be operated by way of frustrated total internal reflection (F-TIR) in order to recognize the movement of a finger on an imaging surface. This type of mouse is herein referred to as a finger-mouse. 
         [0019]      FIG. 1   a  shows an example of a fingermouse  100  in accordance with the prior art. The fingermouse includes a base  102 , an imaging element shown generally at  104 , an LED  106 , and a sensor  108 . The top surface  110  of the imaging element  104  is a frustrated total internal reflection (F-TIR) surface. In addition, the imaging element includes a collimating lens  112  between the LED and the imaging element and an imaging lens  114  between the imaging element and the sensor. The imaging element further includes two total internal reflection mirror elements  116  which direct illumination from the collimating lens to the frustrated total internal reflection surface and then from the frustrated total internal reflection surface to the imaging lens. The lower surface  118  of the imaging element is substantially flat.  FIG. 1   b  shows the frustrated total internal reflection surface  110  with the LED  106  and the sensor  108  there below as viewed from above. 
         [0020]    The present embodiments provide custom shaped illumination, such as a ring, other shape or perimeter, to an optical device, such as a fingermouse. This is achieved by using a single light source, such as an LED and changing the shape of the imaging element. This enables the light source to be collimated onto an edge of the imaging element. The custom shaped illumination can be used to brighten the fingermouse and give rise to a number of aesthetic or optical effects. These effects can include showing logos, colors or moods on the mouse which are in tune with the phone or camera design, etc. Other uses include improved backlighting and illumination making the mouse easier to use in bad lighting conditions. 
         [0021]    Referring to  FIG. 2 , the imaging element  200  of an optical device in accordance with a present embodiment is shown. The imaging element  200  is illuminated by LED  202 . The imaging element includes a curved surface  204 , which is shaped in a predetermined manner, to ensure that illumination from the light source may be directed to certain areas of the top surface of the imaging element. The areas on the top surface are roughened areas  206  which scatter illumination from the source. The roughened surface is rough to the touch and can be any appropriate shape or size although in a preferred embodiment the roughened surface forms a circular ring or a square perimeter around the edge of the imaging element. 
         [0022]    A mask  208  is positioned to prevent illumination from the light source heading directly to the top surface of the imaging element. The mask can be replaced by an appropriate coating on the curved surface  204 . In an alternative embodiment, the curved surface may be roughened so that additional backlighting is provided by the LED  202  at the top surface of the imaging element. In yet another embodiment, the mask can incorporate a number of holes, forming a pattern, and coupled to a roughened curved surface to thereby produce a logo display on the top surface of the optical element when the mask is illuminated by the LED  202 . 
         [0023]      FIG. 3  shows a further embodiment of an optical element  300 . The optical element  300  is illuminated by light source  302  and includes a mask  304 . The various aspects of the light source and mask are equivalent to the earlier embodiment. The imaging element  300  includes a total internal reflection surface  306  which ensures that more light is directed to the roughened surface than in the  FIG. 2  embodiment. The  FIG. 3  embodiment includes one internal reflection surface  306  but it may be appreciated that a further surface can be provided on the opposite side. 
         [0024]    The optical element ( 200  or  300 ) can be made from any transparent material. However, due to the complexity of the various surfaces and shapes thereof, a moldable material is preferred. Possible materials include polycarbonate and acrylics, such as poly (methyl methacrylate) PMMA, Lexan 121R, Makrolon 2405, glass, Polyethylene, PVB (Polyvinyl butyral) or any other appropriate material. 
         [0025]    Referring to  FIG. 4   a  an optical imaging device is shown generally at  400 . The optical imaging device includes an optical element  402 , which may be shaped as previously described, or in any other appropriate shape. The device also includes a first light source  404 , the illumination of which is focused onto a mousing surface  406  on the top surface of optical element  402 . The mousing surface  406  responds to movement of a finger or other appropriate pointing device on the surface to set up the F-TIR of the illumination, which is detected by the sensor  408 . The F-TIR surface can reflect, absorb or scatter the illumination. The optical devices include a second light source  410  and a mask  412 . The mask can be replaced by a coating on the curved surface  414  of the optical element  402  or by other appropriate methods as earlier described. The illumination from the second light source is blocked from the mousing surface  406  by way of the mask. Any illumination that is not blocked by the mask is directed to roughened surfaces  416  around the edge of the optical element  402  by way of the shape and configuration of the optical element. 
         [0026]    As can be seen in  FIG. 4   b , the mousing surface  406  shows a reflection of the mask  418  and a ring  420  defining the roughened surface. The ring  420  comprises an upper ring  422  and a lower half ring  424 . The ring is shown as straight sided with curved corners but could be any other shape including fully circular or any other straight edged form or perimeter depending on the optical element shape and any user requirements. The brightness of the ring  418  may depend upon the configuration of the optics of the fingermouse and could be dark or similar to the half rings depending on the shape, nature and orientation of the optical elements. 
         [0027]    Referring to  FIG. 5   a  a further embodiment of an optical device  500  is shown. The majority of the elements in the second embodiment are equivalent to those in the first embodiment of  FIG. 4  and may not be described in further detail. In the present embodiment, the optical element  502  is formed in a different manner having a gap  504  between the upper surface of the optical element and the input and output end of the optical element for the purposes of illuminating the mousing surface  506 . This gap provides a surface which refracts backlight to the roughened surface and changes the appearance of the mouse. 
         [0028]    It is possible to include more than one second source of illumination, for example, two or more different colored LEDs. These can be separated from one another by an appropriate barrier. The result is a multicolored surface having different regions of the roughened surface being of different colors. 
         [0029]    In an alternative embodiment, the single LED in the center may be changed for a combination of the several LEDs of different colors to allow for dynamic color change of the ring illumination. The orientation of the LED in the embodiment shown in  FIGS. 4 and 5  has the illumination being directed generally upwards. An alternative arrangement as shown in  FIG. 6   a  provides a side emitting LED instead of the standard LED. This allows a greater degree of illumination to be collimated onto the ring surface, and the LED can be closer to the optical element, thereby reducing the size of the optical device. In the side emitting light LED embodiment, the optical element is formed accordingly to ensure the illumination travels in the desired manner. 
         [0030]    The optical element may be of any form shape or size and adaptation may be made to accommodate different orientations of LED and other elements within the device. A potential requirement is that there are essentially two illumination sources: one from the first LED to illuminate a mousing surface and a second that enables illumination of a ring or other shape on the upper surface of the optical element. The examples presented here in have shown entire rings around the edge of the optical elements; however, it would be appreciated that gaps may occur by positioning of certain masking elements to give different patterns. In the diagrams, the illumination for mouse action is shown by a solid line and the illumination for custom shaped ring illumination is shown by a dotted line. 
         [0031]    The distance between the mousing surface and under the first LED or sensor in the present embodiment is in the region of 2.5 mm. This distance is the thickness of the imaging device and can vary between 2 mm and 3 mm. Ideally, the thickness is not generally greater than 5 mm. The imaging device can be formed from a single piece molding. The molding includes each of the individual optical elements shown in the diagrams. The imaging device could alternatively be made in other appropriate ways with different optical elements, which produce the same optical effect. The imaging device may also be made from a number of different elements, rather than a single molding. The technique for forming the imaging device may include techniques other than molding, such as replication, stamping, embossing or machining. 
         [0032]    The sensor is of any appropriate type and may be a CMOS sensor having an array of pixels for measuring reflected light at different locations to produce an image. The illumination sources are, for example, LEDs which may be of any appropriate type and may generate a source in the “optical” or non-optical ranges. Accordingly, reference to optics and optical are intended to cover wavelengths which are not in the human visible range. The optics, which takes the illumination from the source to the imaging surface, may be of any appropriate type. 
         [0033]    The imaging device is intended for use in an optical navigation device; however, it may be appreciated that the imaging device could be used in any appropriate device, for example, fingerprint reader or Lab-on-chip/Bio-Optical sensor systems (which detect chemi-fluorescence for medical and/or bio-testing applications). The optical navigation device may be used in any suitable devices such as a mobile or smart telephone, other personal or communications devices, a computer, a remote controller, access modules for doors and the like, a camera or any other suitable device. There are many variations of the present embodiments which may be appreciated by the person skilled in the art and which are included within the scope of the present invention.