A projection video display apparatus includes a video input unit, a light source, a display element, a projection optical system, and a variable light adjusting function which changes the amount of light incident on the display element. Display modes using the variable light adjusting function are prepared, and one display mode of the display modes can be selected from a menu screen. Further, the display modes of the display video using the variable light adjusting function includes: a first display mode where the input video is displayed while changing a light adjusting amount in accordance with light adjusting control information, which is input from external equipment and is capable of controlling the variable light adjusting function in unit of frame of a projected video; and a second display mode where the input video is displayed while changing a light adjusting amount in accordance with the input video.

Provided are a method and an apparatus for correcting a color convergence error. The method includes: in a dark room environment, collecting a projection light point on a projection screen projected by a projection system, to obtain a projection image; adjusting the test pattern, so that a first projection light point corresponding to the white point of a first coordinate on the test pattern after being projected by a first color light source is located in a center of the projection image; obtaining a second and/or a third projection light points corresponding to the white point of the first coordinate after being projected by a second and/or a third color light sources from the projection image; and adjusting an assembly parameter of the projection system according to a position of the second and/or the third projection light points and a position of the first projection light point.

A light detection circuit for a projector is provided. The light detection circuit includes: a light transistor for receiving and sensing reflected light from a side of a color wheel driving motor of the projector, wherein the side of the color wheel driving motor includes a dark region and a bright region; a bias unit coupled to the light transistor for providing a bias voltage; an operation amplifier including a positive input coupled to the bias unit, a negative input coupled to the light transistor and the bias unit, and an output, the base unit providing the bias voltage to the positive input; and a feedback resistor coupled between the negative input of the operation amplifier and the output, wherein, a resistance of the feedback resistor causes the light transistor to be operated in a linear region.

A lens shift mechanism of one embodiment of the present disclosure includes: a projection lens; a cylindrical housing that holds the projection lens; and an operating unit that moves the cylindrical housing in one axial direction perpendicular to an optical axis of the projection lens. The operating unit includes a pair of a main shaft and a countershaft extending in the one axial direction and disposed to be opposed to each other across the cylindrical housing, and a pair of elastic bodies provided respectively for the main shaft and the countershaft. The pair of elastic bodies are parallel to the one axial direction, and have biasing directions opposite to each other.

An optical system includes a light source, an illumination optical system, and an optical modulator. The lens array and the lens of the illumination optical system are arranged in that order from an upstream side of an optical path of light from the light source. The light shield is disposed at the upstream side relative to the lens in the optical path. The light shield blocks some rays incident within a range of an effective diameter of the lens. The illumination optical system emits the light to the optical modulator. The optical modulator emits the incident light to a first direction and a second direction different from the first direction. A center of an effective diameter of the lens array is offset from a center of the effective diameter of the lens to an opposite side of the light shield in a direction orthogonal to the optical axis.

A light source assembly includes a light source unit, a light collecting unit, a light separating unit and a light converting unit. The light source unit generates a first light beam having a first color and a first optical path. The light collecting unit has a light entering side and a light exiting side and is configured to collimate and condense the light beam incident on the light entering side. The light separating unit is disposed on an area between the light entering side and the light exiting side of the light collecting unit for reflecting the first light beam entering from the light entering side of the light collecting unit. The light converting unit absorbs the first light beam reflected from a light separating unit and generates a converted light beam having a second color.

A composite-optical-system unit (40) includes a plurality of polarization beam splitters (400A, 400B, and 400C), a pair of spacer plates (420 or the like), and an optical element (411). Each of the pair of spacer plates (420) is arranged between the first polarization beam splitter (400A) and the second polarization beam splitter (400C) of the plurality of polarization beam splitters such that a first contact surface is fixed on an emission-side surface (403) of the first polarization beam splitter (400A) by surface contact, and a second contact surface is fixed on an incident-side surface (405a) of the second polarization beam splitter (400C) by surface contact. The optical element (411) is arranged between the pair of spacer plates (420).

An optical module including a transparent component and at least one coil device is provided. The at least one coil device is connected to the transparent component and includes a main body and at least one extending wire. The at least one extending wire is extended out from the main body, the at least one coil device is adapted to be driven by a magnetic force to vibrate along at least one rotation axis, and a length of the at least one extending wire is in positive correlation with a width of the transparent component along a direction. The direction is perpendicular to the at least one rotation axis and perpendicular to an optical axis of the transparent component. In addition, a projector having the optical module is also provided.

A light source assembly includes a light source unit, a light collecting unit, a light separating unit and a light converting unit. The light source unit generates a first light beam having a first color and a first optical path. The light collecting unit has a light entering side and a light exiting side and is configured to collimate and condense the light beam incident on the light entering side. The light separating unit is disposed on an area between the light entering side and the light exiting side of the light collecting unit for reflecting the first light beam entering from the light entering side of the light collecting unit. The light converting unit absorbs the first light beam reflected from a light separating unit and generates a converted light beam having a second color.

A projection system and a control method of a driving current thereof are provided. A power supply of an illumination module provides the driving current to drive a light source to provide an illumination beam. A filter wheel receives the illumination beam and filtered beams are generated. The illumination beam passes through the filter wheel during a first period and a first filtered beam is generated. The illumination beam passes through the filter wheel during a second period and a second filtered beam is generated. The filtered beams include the first filtered beam, the second filtered beam, and an intermediate filtered beam generated during an intermediate period between the first and second periods. A control device controls the power supply to continuously provide the driving current from the first period, through the intermediate period, to the second period.