LIQUID CRYSTAL DISPLAY DEVICE FOR AUTOMOBILE

摘要

PURPOSE:To control automatically light amount of a luminescent element without providing any new photoelectric detector by utilizing a photoelectric detector in an air conditioning automatic control system for an automobile to add the output of said detector to a control circuit for light amount of the luminescent element for a liquid crystal display. CONSTITUTION:To a connection 3 of a photoelectric detector 1 and a fixed resistor 2 in an air conditioning system for an automobile is connected an air conditioning control circuit 5 through a delay circuit 4 having large time constant to control the air conditioning in the automobile in response to solar radiation amount. Also, the external light is introduced from a light introducing hole 10 formed in the upper surface of a dash board through a light guide member 12 projecting a light collecting portion 12a to the back of a liquid crystal display body 11 arranged on the front surface of the dash board. A luminescent element 13 disposed adjacent the light guide member 12 controls light amount with a light amount control circuit 8 which controls the light amount of the liminescent element 13 when integrated value by a integrating circuit 6 consisting of an operational amplifier 7 reaches a predetermined value, i.e. when solar radiation is shaded for a predetermined time or more.