Patent Publication Number: US-2007097049-A1

Title: In-vehicle liquid crystal display device with temperature sensor

Description:
FIELD OF THE INVENTION  
      The present invention relates to in-vehicle liquid crystal display (LCD) devices, and more particularly to an in-vehicle LCD device having a temperature sensor.  
     BACKGROUND  
      Because LCD devices have the advantages of portability, low power consumption, and low radiation, they have been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like. Furthermore, LCD devices are considered by some to have the potential to completely replace CRT (cathode ray tube) monitors and televisions.  
      LCD devices are also applied in all kinds of motor vehicles, where they are known as in-vehicle LCD devices. The motor vehicles may run in all kinds of environments with different temperatures; for example, higher than 35° C. in the summer, or lower than 0° C. in the winter. That is, the in-vehicle LCD devices may need to operate in environments subject to extreme weather conditions. However, the LCD module of a typical in-vehicle LCD device has a range of normal operating temperatures. If the prevailing environment temperature is out of this range, the display quality of the LCD module may be impaired, and the LCD device may even fail altogether.  
      Accordingly, what is needed is an in-vehicle LCD device that can overcome the above-described deficiencies.  
     SUMMARY  
      In one aspect, an in-vehicle LCD device includes a temperature sensor, a power circuit selector, a power circuit, a reverse power circuit, a Peltier member, and an LCD module having the Peltier member operatively coupled thereto. The temperature sensor, the power circuit selector, the power circuit, the Peltier member, and the LCD module are electrically connected series. And the reverse power circuit is electrically connected between the power circuit selector and the Peltier member.  
      In another aspect, an in-vehicle LCD device includes a temperature sensor; a power circuit selector electrically connected to the temperature sensor; a peltier member; a first power circuit and a second power circuit electrically connected in parallel between the power circuit selector and the peltier member; and an LCD module electrically connected to the peltier member, and having the peltier member operatively coupled thereto.  
      Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
      The drawing is a block diagram of an in-vehicle LCD device according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Reference will now be made to the drawings to describe preferred and exemplary embodiments of the present invention in detail.  
      Referring to the drawing, an in-vehicle LCD device  100  includes a temperature sensor  101 , a power circuit selector  102 , a power circuit  103 , a reverse circuit  104 , a reverse power circuit  105 , a Peltier member  106 , and an LCD module  107 .  
      The temperature sensor  101 , the power circuit selector  102 , the power circuit  103 , the Peltier member  106 , and the LCD module  107  are electrically connected one by one in series. Further, the power circuit selector  102  is electrically connected with the reverse circuit  104 , the reverse circuit  104  is electrically connected with the reverse power circuit  105 , and the reverse power circuit  105  is electrically connected with the Peltier member  106 .  
      In operation, the temperature sensor  101  detects a temperature of the environment that the in-vehicle LCD device  100  is currently in, and transmits a signal representing a value of the environmental temperature to the power circuit selector  102 . The power circuit selector  102  compares the environmental temperature with a critical high temperature and a critical low temperature stored therein. That is, the high and low critical temperatures are input to the power circuit selector  102  in advance, according to a normal operational temperature range of the LCD module  107 . If the environmental temperature is higher than the critical high temperature of the LCD module  107 , the power circuit selector  102  turns on the power circuit  103  to make the Peltier member  106  operate in a reverse operational state. At this time, the Peltier member  106  is maintained in a heat discharging state in order to rapidly discharge heat from the LCD module  107  and bring the LCD module  107  within its normal operational temperature range. On the other hand, if the environmental temperature is lower than the critical low temperature of the LCD module  107 , the power circuit selector  102  turns on the reverse circuit  104  and the reverse power circuit  105  to make the Peltier member  106  operate in a normal operational state. At this time, the Peltier member  106  is maintained in a heat generating state in order to increase the operational temperature of the LCD module  107  and bring the LCD module  107  within its normal operational temperature range. If the environmental temperature is in the range between the critical high temperature and the critical low temperature, the power circuit selector  102  does not turn on any of the power circuit  103 , the reverse circuit  104 , and the reverse power circuit  105 . That is, the Peltier member  106  is in an off state. This saves on power consumption of the in-vehicle LCD device  100 .  
      With this configuration, the in-vehicle LCD device  100  can automatically control the Peltier member  106  to be in either one of the normal and reverse operation states or be turned off, according to the environmental temperature detected by the temperature sensor  101 . Therefore the operational temperature of the LCD module  107  can be adjusted to be in the normal range. The in-vehicle LCD device  100  may be employed in environments subject to all kinds of temperature variations, with the LCD module  107  being able to consistently provide a high quality, reliable display.  
      In a further or alternative embodiment of the in-vehicle LCD device  100 , the temperature sensor  101  may be used to detect the operational temperature of the LCD module  107 . In such case, the power circuit selector  102  controls the power circuit  103 , the reverse circuit  104 , and the reverse power circuit  105  having regard to or according to the operational temperature of the LCD module  107 .  
      It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, 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.