Laser projection apparatus

A laser projection apparatus, comprising a laser light source, a light combining mirror group, an optical path shaping lens, a diffusion wheel, a light collecting device, a light valve, a projection lens, a main control circuit, a diffusion wheel driving circuit and a temperature sensor, wherein

• the laser light source is configured to emit laser beams of three colors;
• the combining mirror group is configured to combine the laser beams of three colors;
• the optical path shaping lens is configured to shape a light path of the combined laser beams;
• and the combined laser beams are transmitted to the optical path shaping lens and then incident to the diffusion wheel;
• the diffusion wheel is configured to homogenize the laser beams and then transmit the laser beams to the light collecting device;
• the light valve is configured to modulate light of each color into an image light beam and transmit the image light beam to the projection lens;
• the projection lens is configured to project the image light beam onto a projection screen;
• the diffusion wheel includes a motor and a diffusion portion, wherein the motor is a three-phase motor;
• the temperature sensor is electrically connected to the main control circuit, and configured to detect an ambient temperature;
• the main control circuit is configured to:
• determine a target starting current according to the ambient temperature;
• determine a duty cycle of a second startup pulse width modulation signal according to the target starting current, and provide the second startup pulse width modulation signal to the diffusion wheel driving circuit;
• and output an operating pulse width modulation signal to the diffusion wheel driving circuit when the diffusion wheel reaches a target rotation speed, wherein the target starting current is a minimum drive current required to drive the motor from standstill to starting to rotate, and the target rotation speed is a preset speed at which the diffusion wheel operates normally and speckles can be eliminated;
• and
• the diffusion wheel driving circuit is configured to drive the three-phase motor to drive the diffusion portion in response to each of the second startup pulse width modulation signal and the operating pulse width modulation signal.