Abstract:
An overheating prevention apparatus for use in a display apparatus is provided. The display apparatus comprises at least one fan running at at least one initial rotation speed. The overheating prevention apparatus comprises a first temperature sensor, a second temperature sensor and a processing module. The first temperature sensor is used for sensing an environment temperature and generating a first signal according to the environment temperature. The second temperature sensor is used for sensing an inner temperature of the display apparatus and generating a second signal according to the inner temperature. The processing module adjusts the at least one fan from the at least one initial rotation speed to at least one first running rotation speed according to the first signal and the second signal. The display apparatus using the present invention can automatically adjusts the speed of the fan so that the display apparatus works correctly.

Description:
[0001]    This application claims priority to Taiwan Patent Application No. 099130504 filed on Sep. 9, 2010, which is hereby incorporated by reference in its entirety. 
       CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to an overheating prevention apparatus for use in a display apparatus, and more particularly, to an overheating prevention apparatus for use in a display apparatus, which can automatically adjust the rotation speed of a fan according to different environments. 
         [0005]    2. Descriptions of the Related Art 
         [0006]    With the development of science and technology, display apparatuses have become indispensable electronic products to people&#39;s life. Among such display apparatuses, projection apparatuses for large-scale screens are even more widely used in, for example, conference rooms, home theaters, classrooms and the like. Because of the wide application thereof, projection apparatuses are often used in various environments. Furthermore, light emitting elements of the projection apparatuses will generate massive heat energy during operation, so in order to ensure that the projection apparatuses will not be shut down due to overheating, most of the projection apparatuses are used in combination with heat sinks such as fans. 
         [0007]    However, fans usually generate unavoidable noises during operation, and this has an influence on the service quality, particularly when the fans run at a high rotation speed. Accordingly, many ways of controlling fans have been developed to adjust the rotation speed of the fans correspondingly. Among such approaches, a common approach is to adjust the fan manually, which is inexpensive and simple in design and only requires the user to determine through sensation the temperature of the projection apparatus to manually set the rotation speed of the fan. However, if a false determination is made, it will easily cause damage to the elements of the projection apparatus. 
         [0008]    Additionally, there is also an approach to automatically set the rotation speed of a fan by using a temperature sensor. This approach mainly relies on the temperature sensor in a projection apparatus to determine the operating temperature and, accordingly, adjust the rotation speed of the fan automatically. Although the automatic method is better than manual adjustment, the conventional way of automatically sensing the temperature usually operates in the following way: a temperature threshold is set, and if the temperature of the projection apparatus goes higher than the temperature threshold, then the rotation speed of the fan is increased; conversely, if the temperature of the projection apparatus goes lower than the temperature threshold, then the rotation speed of the fan is decreased. In this way, if the operating temperature of the projection apparatus is close to the temperature threshold, then the fan will run at a fluctuating rotation speed due to the instantaneous rise or fall in the temperature. Consequently, apart from the failure to obtain the preferred balance between the rotation speeds of the fan, the noises of the fan and the operating temperature, the service life of the fan may further be shortened. 
         [0009]    Furthermore, when the projection apparatus is used at different heights above the sea level, the operating environment may be determined by using a pressure sensor so that the rotation speed of the fan is adjusted according to the height above sea level. However, the method in which the height is determined by using the pressure sensor is very costly, so it is not widely accepted by the public. 
         [0010]    Accordingly, a need still exists in the art to solve the aforesaid problem so that the projection apparatus can adjust the heat dissipation device according to different environments and an optimal balance can be achieved between the heat dissipation, the noises and the price simultaneously. 
       SUMMARY OF THE INVENTION 
       [0011]    To solve the aforesaid problem, an objective of the present invention is to provide an overheating prevention apparatus for use in a display apparatus. By using the overheating prevention apparatus, the display apparatus can adjust the rotation speed of a fan of the overheating prevention apparatus automatically and evenly according to different operating environments to ensure proper operation of both the overheating prevention apparatus and the display apparatus. 
         [0012]    To accomplish the aforesaid objective, the present invention provides an overheating prevention apparatus for use in a display apparatus. The display apparatus comprises at least one fan, and the at least one fan runs at at least one initial rotation speed. The overheating prevention apparatus comprises a first temperature sensor, a second temperature sensor and a processing module. The first temperature sensor is configured to sense the temperature in the environment and generate a first signal according to the environment temperature. The second temperature sensor is configured to sense the inner temperature of the display apparatus and generate a second signal according to the inner temperature. The processing module is configured to adjust the at least one fan from the at least one initial rotation speed to at least one first running rotation speed according to the first signal and the second signal. 
         [0013]    Another objective of the present invention is to provide a projection apparatus, which comprises at least one fan, a first temperature sensor, a second temperature sensor and a processing module. The at least one fan runs at at least one initial rotation speed. The first temperature sensor is configured to sense the temperature in the environment and generate a first signal according to the environment temperature. The second temperature sensor is configured to sense an inner temperature of the projection apparatus and generate a second signal according to the inner temperature. The processing module is configured to adjust the at least one fan from the at least one initial rotation speed to at least one first running rotation speed according to the first signal and the second signal. 
         [0014]    According to the above descriptions, the present invention can employ the two sensors of the display apparatus to detect the environments to generate operating parameters in the various environments, and according to the operating parameters, further adjust the fan of the display apparatus automatically and evenly so that the display apparatus can operate normally in the various environments. 
         [0015]    The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic view of a display apparatus of the present invention; 
           [0017]      FIG. 2A  shows a first corresponding relation table of the present invention; 
           [0018]      FIG. 2B  is a coordinate graph of the first corresponding relation table of the present invention; 
           [0019]      FIG. 3A  shows a second corresponding relation table of the present invention; and 
           [0020]      FIG. 3B  is a coordinate graph of the second corresponding relation table of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    In the following description, an overheating prevention apparatus of the present invention will be explained with reference to embodiments thereof. It shall be appreciated that the embodiments of the present invention are not intended to limit the present invention to any specific environment, applications or particular implementations described in these embodiments. Therefore, the description of these embodiments is only for the purpose of illustration rather than to limit the present invention. 
         [0022]      FIG. 1  illustrates a schematic view of a display apparatus  1  of the present invention. It shall be particularly appreciated that in this embodiment, the display apparatus  1  is a projection apparatus; however, it is not limited thereto, and the display apparatus  1  may be any other display equipment in which overheating has to be prevented. The display apparatus  1  comprises a fan  11  and an overheating prevention apparatus  13 . The overheating prevention apparatus  13  further comprises a first temperature sensor  131 , a second temperature sensor  133  and a processing module  135  comprising a memory  137 . 
         [0023]    After the display apparatus  1  is turned on, the fan  11  runs at an initial rotation speed. Then, the first temperature sensor  131  detects an environment temperature T i  of the environment where the display apparatus  1  is located and, according to the environment temperature T i , generates a first signal  132 , which is then transmitted to the processing module  135 . The second temperature sensor  133  detects an inner temperature T c  of the display apparatus  1  and, according to the inner temperature T, generates a second signal  134 , which is also transmitted to the processing module  135 . Then, according to the first signal  132  and the second signal  134 , the processing module  135  adjusts the fan  11  from the initial rotation speed to a first running rotation speed. 
         [0024]    In detail, after being started up, the processing module  135  firstly determines the initial rotation speed of the fan  11  to facilitate heat dissipation in the start-up process; and after the display apparatus  1  has run for a default time period, the processing module  135  determines the environment temperature T i  according to the first signal  132  transmitted by the first temperature sensor  131  and the inner temperature T c  of the display apparatus  1  according to the second signal  134  transmitted by the second temperature sensor  133 . Then, the processing module  135  determines the environment height at which the display apparatus  1  is currently located according to the environment temperature T i , the inner temperature T c  and a first corresponding relation table  136  stored in the memory  137 . 
         [0025]    Next, in reference to  FIG. 2A , the first corresponding relation table  136  comprises a first temperature corresponding relation  1361 , a second temperature corresponding relation  1362  and a third temperature corresponding relation  1363  between the environment temperature T i  and the inner temperature T c . The method in which to determine the environment height according to C ij  and L ij  will be elucidated in the following description. Firstly, it shall be particularly appreciated that, (C 11 , I 11 ), (C 12 , I 12 ), (C 13 , I 13 ), (C 14 , I 14 ) and (C 15 , I 15 ) in the first temperature corresponding relation  1361  generally exhibit a linear relation; therefore, for ease of understanding, the first temperature corresponding relation  1361  is depicted as a line segment  21  in a coordinate graph of  FIG. 2B . Similarly, the second temperature corresponding relation  1362  and the third temperature corresponding relation  1363  are also depicted as a line segment  22  and a line segment  23  respectively for the purpose of the following description. 
         [0026]    First, the processing module  135 , with a value of the environment temperature T i  as a reference point, determines the environment height according to the value of the inner temperature T c . For example, when the processing module  135  determines that the value of the environment temperature T i  is I 1 , the processing module  135 , according to a relation represented by the first temperature corresponding relation  1361  (the line segment  21 ), determines whether the inner temperature T c  exceeds the value C 11  corresponding to I 1  in the first temperature corresponding relation  1361  to determine the environment height. In more detail, when the value of the environment temperature T i  is I 1 , the processing module  135  determines that the value of the inner temperature T c  is smaller than or equal to C 11 , then the environment height is within a first environment height range R 1  defined by the first temperature corresponding relation  1361 . 
         [0027]    On the contrary, when the value of the environment temperature T i  is I 1 , the processing module  135  determines that the value of the inner temperature T c  is greater than C 11 , then this means that the environment height has exceeded the first environment height range R 1 . In this case, according to the second temperature corresponding relation  1362 , the processing module  135  further determines whether the environment height is within a second environment height range R 2  defined by the second temperature corresponding relation  1362 . 
         [0028]    In more detail, after determining that the environment height has exceeded the first environment height range R 1 , the processing module  135  similarly determines the environment height according to the value of the inner temperature T c  with the value of the environment temperature T i  as the reference point. For example, after the processing module  135  determines that the value of the environment temperature T i  is I 1  and the value of the inner temperature T c  is greater than C 11 , the processing module  135 , according to a relation represented by the second temperature corresponding relation  1362  (the line segment  22 ), determines whether the value of the inner temperature T c  is smaller than or equal to C 21 . If the answer is “yes”, this represents that the environment height is within the second environment height range R 2 ; otherwise, if the answer is “no”, then according to the third temperature corresponding relation  1363 , the processing module  135  further determines whether the environment height is within a third environment height range R 3  defined by the third temperature corresponding relation  1363 . Similarly, subsequent determining operations are identical to those of the aforesaid process flow, and thus, will not be further described herein. 
         [0029]    After determining the environment height, the processing module  135  first adjusts the fan  11  from the initial speed to the first running rotation speed according to the environment height so that the heat dissipation mode corresponding to the environment height of the display apparatus  1  is used. Then, after determining the environment height of the display apparatus  1  and the first running rotation speed, the processing module  135  determines a new rotation speed of the fan  11  according to a second corresponding relation table  138  stored in the memory  137 . 
         [0030]    It shall be particularly appreciated that the second corresponding relation table  138  has recorded therein relations between the environment temperature T c  and the first running rotation speed when the display apparatus  1  is within the first environment height range R 1 , the second environment height range R 2  or the third environment height range R 3  respectively. According to this, the fan  11  is adjusted from the first running rotation speed to a second running rotation speed. In brief, the processing module  135  adjusts the rotation speed of the fan  11  again according to the environment temperature T c  represented by the first signal  132  and the second corresponding relation table  138 . 
         [0031]    Next, in reference to  FIG. 3A , the second corresponding relation table  138  comprises a first rotation speed relation  1381 , a second rotation speed relation  1382  and a third rotation speed relation  1383  between the environment temperature T i  and the first running rotation speed when the display apparatus  1  is within the first environment height range R 1 , the second environment height range R 2  and the third environment height range R 3  respectively. Likewise, for ease of understanding, the first rotation speed relation  1381  is depicted as a line segment  31  in a coordinate graph of  FIG. 3B . Similarly, the second rotation speed relation  1382  and the third rotation speed relation  1383  are also depicted as a line segment  32  and a line segment  33  respectively for purposes of the following description. 
         [0032]    In detail, when the display apparatus  1  is within the first environment height range R 1 , a corresponding relation between the rotation speed of the fan  11  and the environment temperature T i  is as shown by the first rotation speed relation  1381  (the line segment  31 ). For example, if the display apparatus  1  is within the first environment height range R 1 , then when the value of the environment temperature T i  is equal to I 6 , the fan  11  is adjusted to a rotation speed of W 12 . 
         [0033]    Similarly, when the display apparatus  1  is within the second environment height range R 2 , a corresponding relation between the rotation speed of the fan  11  and the environment temperature T i  is as shown by the second rotation speed relation  1382  (the line segment  32 ). For example, if the display apparatus  1  is within the second environment height range R 2 , then when the value of the environment temperature T i  is equal to I 7 , the fan  11  is adjusted to a rotation speed of W 23 . In other conditions, the rotation speed of the fan  11  is adjusted in a similar way, and this will not be further described herein. 
         [0034]    It shall be particularly emphasized that to ensure the normal operation of the display apparatus  1  more completely, the memory  137  further stores a first upper bound value C limit , and when the environment temperature T i  exceeds the first upper bound value C limit , the processing module  135  shuts down the display apparatus  1  according to the first signal  132 . The memory  137  further stores a second upper bound value I limit , and when the inner temperature T c  exceeds the second upper bound value I limit , the processing module  135  shuts down the display apparatus  1  according to the second signal  134 . In this way, by means of the first upper bound value C limit  and the second upper bound value I limit , the display apparatus  1  can be more completely protected from overheating. 
         [0035]    According to the above descriptions, the display apparatus  1  first determines a height at which it is located according to the environment temperature T c , the inner temperature T i  and what was recorded in the first corresponding relation table  136 , and then determines a rotation speed of the fan  11  based on the height at which the display apparatus  1  is located and according to the environment temperature T c  and what was recorded in the second corresponding relation table  138 . In this way, an optimal balance between the temperature and the noises can be obtained at a lower cost and with a higher control accuracy, thereby accomplishing an efficacy that would be impossible in the prior art. 
         [0036]    The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.