In order to optimize air-conditioning in the interior space of a vehicle, the temperature of the interior space must be measured with precision.
Representative examples of a method which is widely used for measuring the interior temperature of a vehicle may include a non-contact temperature measurement method using an infrared sensor. According to the non-contact temperature measurement method, the temperature of a passenger's face may be measured in a non-contact manner through an infrared (IR) sensor installed in the vehicle interior. Then, air-conditioning in the vehicle interior may be controlled according to the measurement result.
FIG. 1 illustrates a conventional automotive air-conditioning system based on such a non-contact temperature measurement method using an IR sensor.
As indicated by reference numeral 101 in FIG. 1, the automotive air-conditioning system includes a front sensor 105 mounted on a dashboard 103 positioned at the front of the vehicle interior and a rear sensor 109 mounted on the rear surface of a front seatback 107. The front sensor 105 and the rear sensor 109 are mounted to be inclined backward and upward. As indicated by arrows in FIG. 1, the front and rear IR sensors 105 and 107 directly measure the temperatures of a driver's face and a passenger's face.
However, the arrangement of the front and rear sensors 105 and 107 may have a problem in that, when the temperature of the face of a passenger in a rear seat is measured, the rear sensor 107 may be covered by a seat cover of a front seat. Thus, the seat cover of the front seat must be removed or deformed to expose the rear sensor 107 to the outside.
Furthermore, the distance between the rear sensor 107 and the passenger in the rear seat is very short. Thus, in order to measure the temperature of the upper and lower bodies of the passenger as well as the temperature of the face of the passenger in the rear seat or measure the temperatures of passengers in the left and right rear seats through one sensor, an IR sensor with a wide-angle lens must be used or the number of sensors must be increased. Therefore, the sensor installation cost inevitably increases.
In order to solve such a problem, another conventional automotive air-conditioning system represented by reference numeral 201 in FIG. 2 includes an IR sensor 203 which is disposed at a front top position of the interior of a vehicle, such as a room lamp unit, in order to measure the temperature of the entire body of a passenger in a rear seat. The one IR sensor 203 with a narrow-angle lens may be used to measure the temperatures of the entire bodies of passengers in left and right rear seats 207 and 208 and the temperature of a part of the faces of passengers in left and right front seats 205 and 206.
However, the IR sensor 203 disposed in such a manner has a narrow viewing angle as indicated by a solid line of FIG. 2. Thus, the IR sensor 203 cannot secure a wide viewing angle which may be covered through a sensor with a wide-angle lens, as indicated by a dotted line of FIG. 2. Therefore, in order to measure the temperatures of the passengers in the left and right front seats 205 and 206 as well as the left and right rear seats, an expensive sensor with a wide-angle lens must be employed, and the number of sensors used for the system must be increased. As a result, the manufacturing cost including the installation cost inevitably increases.