Abstract:
A laser control apparatus includes a detector and a switch module. The detector is for detecting states of a mechanism having a closed state in which the mechanism blocks a laser and an opened state in which the mechanism unblocks the laser. The switch module is for transmitting an emitting command to a laser unit to emit the laser. When the opened state is detected, the switch module stops transmitting the emitting command. An electronic device using the laser control apparatus is also disclosed.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to lasers, and particularly to an electronic device using a laser control apparatus. 
         [0003]    2. Description of related art 
         [0004]    Laser diodes emit light in narrow, low-divergence monochromatic, beams with well-defined wavelengths. Because of these excellent optical features, lasers are widespread and are used in laser printers, bar code readers, optical storage devices, etc. 
         [0005]    However, under some circumstances, the laser diodes are not turned off immediately when the laser is turned off, thus, electronic devices using the laser diodes may waste power or even harm people unintentionally. 
         [0006]    Therefore, a laser control apparatus for an electronic device is needed in the industry to address the aforementioned deficiency. 
       SUMMARY 
       [0007]    A laser control apparatus includes a detector and a switch module. The detector is for detecting states of a mechanism having a closed state in which the mechanism blocks a laser and an opened state in which the mechanism unblocks the laser. The switch module is for transmitting an emitting command to a laser unit to emit the laser. When the opened state is detected, the switch module stops transmitting the emitting command. An electronic device using the laser control apparatus is also disclosed. 
         [0008]    Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic block diagram showing a laser control apparatus controlling a laser unit in accordance with an exemplary embodiment. 
           [0010]      FIG. 2  is a circuit diagram showing detailed circuits of the laser control apparatus of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Reference will now be made to the drawings to describe a preferred embodiment of the present laser control apparatus. 
         [0012]    Referring to  FIG. 1 , a laser control apparatus  100  in accordance with an exemplary embodiment is used to control a laser unit  10  that may be a laser diode or an array of laser diodes. The laser control apparatus  100  is enclosed in a portable digital versatile disc (DVD) player (not shown) to detect operations, such as closing and opening of a cover  20 , so as to turn on or off the laser unit  10 . When the cover  20  is closed, lasers emitted from the laser unit  10  are blocked by the cover  20 . When the cover  20  is opened, the laser unit  10  stops emitting the lasers correspondingly. In other embodiments, the laser control apparatus  100  may be enclosed in a laser printer, a bar code reader, or other electronic devices. 
         [0013]    The laser unit  10  is configured for emitting the lasers to perform some functions. In this embodiment, the laser unit  10  is an optical pickup head (OPU) configured for emitting lasers to an optical disc and receiving the lasers reflected from the optical disc to read information from or write information to the optical disc. 
         [0014]    The laser control apparatus  100  includes a processor  112 , a switch module  114 , a driver  116 , and a detector  118 . The processor  112  transmits emitting commands to the laser unit  10  via the switch module  114 , and correspondingly the laser unit  10  emits the lasers. The processor  112  also receives data from the laser unit  10  converted from the information, and generates servo commands based on the data. The switch module  114  controls an electrical connection between the laser unit  10  and the processor  112  based on the detected results of the detector  118 . The driver  116  controls movements, such as focusing and tracking, of the laser unit  10  with respect to the optical disc based on the servo commands. The detector  118  detects operations of the cover  20  of the DVD player. 
         [0015]    In the embodiment, when a closing operation of the cover  20  is detected, that is, the cover  20  is in a closed state, the detector  118  makes no response. When an opening operation of the cover  20  is detected, that is, the cover  20  is in an opened state, the detector  118  generates an open signal. Based on the open signal, the switch module  14  is turned off, and opens the electrical connection. 
         [0016]    Referring also to  FIG. 2 , detailed circuits of the switch module  114  and the detector  118  in this embodiment are shown. The processor  112  includes a first contact  182  and a second contact  184  connected to the laser unit  10  via the switch module  114 . The first contact  182  is used for transmitting a first emitting command to the laser unit  10 , and correspondingly the laser unit  10  emits red lasers for DVD (digital versatile disc). The second contact  184  is used for transmitting a second emitting command to the laser unit  10 , and correspondingly the laser unit  10  emits infrared lasers for CD (compact disc). 
         [0017]    The switch module  114  includes three bipolar junction transistors (BJT)  142 ,  144 , 146 , and two resistors  143 , 145 . The emitter of the BJT  144  is connected to the first contact  182  of the processor  112 , the collector of the BJT  144  is connected to the laser unit  10 , and the base of the BJT  144  is connected to a node  147 . The emitter of the BJT  146  is connected to a second contact  184  of the processor  112 , the collector of the BJT  146  is connected to the laser unit  10 , and the base of the BJT  146  is connected to the node  147 . Therefore, the BJTs  144 ,  146  function as two electronic switches correspondingly for controlling a first electrical connection between the laser unit  10  and the first contact  182  and a second electrical connection between the laser unit  10  and the second contact  184 . 
         [0018]    One end of the resistor  143  is connected to the node  147 , and the other end of the resistor  143  is connected to a first power source V 1 . The resistor  143  is used for transmitting a first power from the first power source V 1  to the node  147 . The node  147  is connected to the collector of the BJT  142 . The emitter of the BJT  142  is connected to ground, and the base of the BJT  142  is connected to a node  149 . The BJT  142  also functions as an electrical switch that controls a voltage of the node  147 . 
         [0019]    One end of the resistor  145  is connected to the node  149 , and the other end of the resistor  145  is connected to a second power source V 2 . The resistor  145  is used for transmitting a second power from the second power source V 2  to the node  149 . The node  149  is connected to the detector  118 . 
         [0020]    The detector  118  includes a single-pole single-throw (SPST) switch  120 . One end of the SPST switch  120  is connected to the node  149 , and the other end of the SPST switch  120  is connected to ground. The SPST switch  120  is used for controlling a voltage of the node  149 . In the embodiment, the SPST switch  120  is disposed adjacent to the tray of the DVD player. 
         [0021]    A detailed description is given as follows to introduce a principle of the laser control apparatus  100 . Only one of the first contact  182  and the second contact  184  is activated at any one time by the processor  112  according to a type of the optical disc, ie, CD or DVD, loaded in the DVD player. Take the DVD as an example, the first contact  182  is activated with a low level voltage while the second contact  184  is held with a high level voltage. When the cover  20  is closed, the SPST switch  120  is closed, and the node  149  is pulled down lower than the turn-on voltage for the BJT  142 . Therefore, the BJT  142  is turned off. The node  147  receives a high level voltage from the first power source V 1  via the resister  143 . Consequently, the BJT  144  is turned on while the BJT  146  is turned off. The first electrical connection is closed, but the second electrical connection is opened. The laser unit  10  receives the first emitting command to emit the red lasers. 
         [0022]    When the cover  20  is opened, the SPST switch  120  is turned off. The node  149  receives a high level voltage from the second power source V 2  via the resister  145 . The first BJT  142  is turned on, thus the node  147  is pulled down lower than the turn-on voltage for the BJTs  144  and  146 . Consequently, the BJTs  144 ,  146  are turned off, and the first and the second electrical connections are opened. Therefore, the laser unit  10  stops emitting lasers. 
         [0023]    As mentioned above, in the embodiment, the laser control apparatus  100  utilizes the detector  118 , to detect the closed state and the opened state of the cover  20  of the DVD player, and the switch module  114 , to control the laser unit  10 , to emit lasers. Therefore, whenever the cover  20  is opened, the laser unit  10  stops emitting the lasers immediately. In other embodiments, the cover  20  of the DVD player can be replaced with other mechanisms of other electronic devices, such as a lid of a laser printer, to establish a detecting relationship with the detector  118 . 
         [0024]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.