Projection device and control method thereof

Abstract

The invention discloses a projection device and a control method thereof. The control method of the projection device comprises the steps of controlling rotation of a motor of a wavelength conversion module, wherein the motor is provided with a single pair of magnetic poles; acquiring a first counter electromotive force of the motor, wherein a cycle of the first counter electromotive force corresponds to a circle of rotation of the motor, and each cycle of the first counter electromotive force is provided with a positive zero-crossing point and a negative zero-crossing point; judging the relative position of a wavelength conversion element according to the positive zero-crossing point or the negative zero-crossing point, that is, the zero-crossing point with unique counter electromotive force waveform of the motor with the single pair of magnetic poles replaces a position mark on a traditional color wheel module, so that problems existing in the traditional position mark are avoided. The control method disclosed by the invention is more accurate compared with a traditional time making method, and can meet a requirement of high accuracy of an existing projection device and a laser projection device in particular.

Description

technical field [0001] The present invention relates to a projection device and its control method, in particular to a projection device and its control method for determining the relative position of a wavelength conversion element according to the characteristics of the electromotive force of a motor. Background technique [0002] The projection device is used for projecting pictures to the imaging area, so as to give viewers an excellent visual experience. At present, projection devices with a color wheel / phosphor wheel structure mainly use the following two judgment methods to detect the phase of the color wheel / phosphor wheel: the first is to use a light-blocking sensor to detect the color wheel / phosphor The phase is distinguished by the position mark pasted on the wheel; the second is to distinguish the phase by using a motor covered with a polarized magnet plus a Hall effect sensor. However, both of the above two judgment methods have disadvantages. For example, the...

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Problems solved by technology

However, the above two judgment methods have disadvantages

For example, the pasted position mark is easy to fall off due to long-term use, and the surface of the position mark and the color wheel / phosphor wheel will accumulate dust due to long-term use, resulting in a decrease in reflectivity and affecting the accuracy of detection. The sensor is also easily affected by dust and affects the sensing ability, and the difference in the optical-mechanical structure of different projection devices (such as light leakage, distance from the sensor to the position mark, etc.) will also affect the sensing signal. Both sensor and Hall effect sensor will increase the design space and cost

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