Abstract:
The present invention relates to a sheet laminating apparatus having a thickness-detecting function. Before the laminating operation is done, the thickness of the article to be laminated is detected by a thickness detecting mechanism of the sheet laminating apparatus. According to the detected thickness, the temperature or the rotating speed of the heating roller of the sheet laminating apparatus is dynamically adjusted.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a sheet laminating apparatus, and more particularly to a sheet laminating apparatus having a thickness-detecting function. 
   BACKGROUND OF THE INVENTION 
   Conventionally, a valuable sheet substance such as a paper sheet or a photograph is usually covered with a protective film for protection because such an article is readily suffered from damage. Typically, a sheet laminating apparatus is used for laminating a sheet substance between two pieces of plastic films. 
   Generally, the conventional sheet laminating apparatus lacks a thickness detecting mechanism. That is, the laminating operation is done under a predetermined parameter. For example, the temperature and/or the rotating speed of the heating roller are adjusted to a proper level. In a case that the sheet substance is too thick or too thin, the laminating operation is readily suffered from failure. Take a sheet substance having a thickness exceeding the allowable specification for example. If the temperature of the heating roller is insufficient or the rotating speed of the heating roller is too fast, the plastic films are not completely softened and thus the sheet substance fails to bond with the plastic films to form a laminated structure. 
   Therefore, there is a need of providing a sheet laminating apparatus having a thickness-detecting function for detecting the thickness of the article to be laminated so as to dynamically adjust the temperature and/or the rotating speed of the heating roller of the sheet laminating apparatus. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a sheet laminating apparatus having a thickness detecting mechanism for detecting the thickness of the article to be laminated. According to the detected thickness, the temperature and/or the rotating speed of the heating roller of the sheet laminating apparatus are dynamically adjusted so that the laminating operation is smoothly performed. 
   In accordance with an aspect of the present invention, there is provided a sheet laminating apparatus having a thickness-detecting function for detecting an article to be laminated by the sheet laminating apparatus. The sheet laminating apparatus includes an entrance channel, an exit channel, a heating roller and a thickness detecting mechanism. The heating roller assembly is arranged between the entrance channel and the exit channel. The thickness detecting mechanism includes an encoding disc, a rotating shaft, a sensing element, a retractable probe and a cable. The encoding disc is rotated with respect to the center rotating axle line. The rotating shaft is arranged on the encoding disc and aligned with the center rotating axle line. The sensing element is disposed beside the encoding disc for detecting a rotation amount of the encoding disc. The retractable probe is partially embedded into the entrance channel. The cable is wound around the rotating shaft. The cable has a first terminal coupled to the retractable probe and a second terminal coupled to a restorable element. 
   In an embodiment, the center rotating axle line of the encoding disc pierces through the entrance channel. 
   In an embodiment, the center rotating axle line of the encoding disc pierces vertically through the entrance channel. 
   In an embodiment, the thickness detecting mechanism further comprises a pulley, which is coupled to the cable, for changing the direction of a portion of the cable. 
   In an embodiment, the restorable element is a spring. 
   In an embodiment, the sensing element is a photo interrupter. 
   In an embodiment, the retractable probe is pressed down by the article to result in a position shift when the article is fed into the entrance channel, thereby rotating the rotating shaft and the encoding disc. 
   The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic cross-sectional view showing a sheet laminating apparatus according to a preferred embodiment of the present invention; and 
       FIG. 2  is a schematic cross-sectional view illustrating operations of the thickness detecting mechanism of the sheet laminating apparatus according to a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   For obviating the drawbacks encountered from the prior art, the present invention provides a sheet laminating apparatus having a thickness detecting mechanism. 
     FIG. 1  is a schematic cross-sectional view showing a sheet laminating apparatus according to a preferred embodiment of the present invention. Hereinafter, the operation principles of the sheet laminating apparatus will be illustrated as follows with reference to  FIG. 1 . 
   As shown in  FIG. 1 , the sheet laminating apparatus  1  principally includes an entrance channel  11 , an exit channel  12 , a heating roller assembly  13 , a heating unit  14  and a thickness detecting mechanism  15 . A receiving portion  113  is defined by the lower surface  111  and the upper surface  112  of the entrance channel  11 . An article  2  to be laminated by the sheet laminating apparatus  1  should be firstly placed in the receiving portion  113  of the entrance channel  11 . In this context, the article  2  to be laminated includes two plastic films and a sheet substance sandwiched between the plastic films. The heating roller assembly  13  includes a pair of adjacent heating rollers  131  and  132 , which are arranged between the entrance channel  11  and the exit channel  12 . After the sheet laminating apparatus  1  is turned on to perform the laminating operation, the heat generated by the heating unit  14  will be transmitted to the heating rollers  131  and  132 . The article  2  fed into the entrance channel  11  is transported and pressed by the heating rollers  131  and  132  so that the sheet substance is bonded with the plastic films to form a laminated structure. The laminated structure is then ejected from the sheet laminating apparatus  1  through the exit channel  12 . 
   Please refer to  FIG. 1  again. The thickness detecting mechanism  15  of the sheet laminating apparatus  1  can be used to detect the thickness of the article  2  to be laminated. According to the detected thickness, the temperatures and/or the rotating speeds of the heating rollers  131  and  132  of the sheet laminating apparatus  1  are dynamically adjusted. The thickness detecting mechanism  15  principally includes an encoding disc  151 , a rotating shaft  152 , a sensing element  153 , a retractable probe  154 , a cable  155 , a pulley  156  and a restorable element  157 . In this embodiment, the encoding disc  151  is an optical encoder. The encoding disc  151  has a grating having opaque portions and transparent portions alternately arranged on the rim thereof. The sensing element  153  used in the present invention is for example a photo interrupter, which is disposed beside the encoding disc  151 . A straight line connected between the emitter and the receiver of the photo interrupter  153  is perpendicular to the rim of the encoding disc  151 . When the encoding disc  151  is rotated with respect to a center rotating axle line  158 , the photo interrupter  153  generates a pulse with alternate high level and low level. According to the wave number and the frequency of the pulse, the rotation amounts of the optical disc (e.g. the rotational position and the rotational velocity) are calculated. It is noted that, however, those skilled in the art will readily observe that numerous modifications and alterations may be made while retaining the teachings of the invention. For example, the encoding disc  151  in other embodiments of the sheet laminating apparatus  1  can be a magnetic encoding disc or an electromagnetic encoding disc. The type of the sensing element  153  is varied according to the encoding disc  151 . In addition to the complete circular shape, the shape of the encoding disc  151  can be varied as required. For example, the encoding disc  151  may have a fan-shape or an arbitrary shape as long as the encoding disc  151  is rotated with respect to a center rotating axle line  158  and the rotation amounts of the encoding disc  151  is detectable by the sensing element  153 . 
   Please refer to  FIG. 1  again. In the thickness detecting mechanism  15  of the sheet laminating apparatus  1 , the encoding disc  151  is preferably parallel to the horizon or slightly tilted. Accordingly, the center rotating axle line  158  of the encoding disc  151  pierces through the lower surface  111  of the entrance channel  11 . For generating a more precise sensing signal from the sensing element  153 , the diameter of the encoding disc  151  inside of the sheet laminating apparatus  1  can be increased. Moreover, since the encoding disc  151  is parallel to the horizon without increasing the height of the sheet laminating apparatus  1 , the sheet laminating apparatus  1  has slim appearance. In this embodiment, the encoding disc  151  is parallel to the horizon and the center rotating axle line  158  of the encoding disc  151  pierces through the lower surface  111  of the entrance channel  11 . In some embodiments, the encoding disc  151  may by tilted with a tilt angle small than 45 degrees provided that the center rotating axle line  158  of the encoding disc  151  pierces through the lower surface  111  of the entrance channel  11 . 
   Please refer to  FIG. 1  again. In the thickness detecting mechanism  15  of the sheet laminating apparatus  1 , the rotating shaft  152  is arranged on the encoding disc  151  and aligned with the center rotating axle line  158 . As a consequence, the rotating shaft  152  is synchronously rotated with the encoding disc  151 . The retractable probe  154  is partially embedded into the entrance channel  11 . When the article  2  is fed into the entrance channel  11 , the retractable probe  154  is pressed down by the article  2  to result in a position shift. In the thickness detecting mechanism  15  of the sheet laminating apparatus  1 , the position shift of the retractable probe  154  is converted into the rotation amount of the encoding disc  151 . One terminal of the cable  155  is coupled to the retractable probe  154 . The other terminal of the cable  155  is partially wound around the rotating shaft  152  and then coupled to the restorable element  157 . 
   When the article  2  is inserted into the receiving portion  113  of the entrance channel  11 , as shown in  FIG. 2 , the retractable probe  154  is pressed down by the article  2  to result in a position shift. According to the position shift of the retractable probe  154 , the rotating shaft  152  wound by the rotating shaft  152  is subject to rotation while the sensing element  153  synchronously detects the rotation amount of the encoding disc  151 . The thickness of the article  2  is calculated according to the rotation amount of the encoding disc  151 . According to the detected thickness, the temperatures and/or the rotating speeds of the heating rollers  131  and  132  of the sheet laminating apparatus  1  are dynamically adjusted. 
   In this embodiment, the restorable element  157  is a spring or another equivalent to a spring in order to offer sufficient tension of the cable  155 . Since the encoding disc  151  is parallel to the horizon or slightly tilted, the sheet laminating apparatus  1  needs at least one pulley  156  to adjust the direction of the cable  155  such that the position shift of the retractable probe  154  can be converted into the rotation amount of the encoding disc  151 . In the embodiment of  FIG. 2 , the retractable probe  154  is moved in the vertical direction. Alternatively, the retractable probe  154  may be swung like a swing arm as long as the swing amount of the retractable probe  154  can be converted into the rotation amount of the encoding disc  151  so to calculate the thickness of the article  2 . 
   In the above embodiments, the heating rollers  131  and  132  of the sheet laminating apparatus  1  are driven by a driving mechanism including a motor and a gear. Moreover, those skilled in the art will readily observe that numerous modifications of adjusting the rotating speeds of the heating rollers  131  and  132  may be made while retaining the teachings of the invention. 
   While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.