The present invention discloses an ambient
light detection circuit for an HUD (
Head Up Display) and belongs to the
automotive electronics field. The circuit mainly comprises a photosensitive
triode T2; the collector of the photosensitive
triode T2 is connected into VCC; the emitter of the photosensitive
triode T2 is connected in series with a
resistor R2 and thereafter is grounded; one path of thevoltage of the upper end of the R2, that is, the
voltage of the non-grounding end of the R2, is directly connected to the A / D_1 end of an MCU, and the other path of the
voltage is connected into an
operational amplifier; and after the signals are amplified a certain number of times, the amplified signals are connected into the A / D_2 of the MCU. According to the ambient
light detection circuit forthe HUD (
Head Up Display) of the invention, one
photoelectric conversion triode is adopted to achieve ambient
light detection in a
large dynamic range; and one sensor is adopted to acquire two pathsof signals to achieve ambient light detection in a
large dynamic range; and therefore, the ambient light detection circuit has the advantages of low cost, high precision and
wide dynamic range. Compared with the prior art, the ambient light detection circuit is lower in cost compared with the cost of a single rain quantity and brightness sensor, is more sensitive than a photosensitive
diode and has a large acquisition range.