A projection system includes a first and second optical system arranged from a reduction side toward an enlargement side. The second optical system includes an optical element having a concave reflection surface and a first lens having negative power, the optical element and first lens arranged from reduction side toward enlargement side. The projection system satisfies the following expressions:

TR≤0.3   (1)

35≤(OAL/imy)×(LL/imy)×TR×(1/NA)≤60   (2)

OAL represents an axial inter-surface spacing from an image formation device to the reflection surface, imy represents a first distance from an optical axis to the largest image height at the image formation device, LL represents the largest radius of the first lens, TR represents a throw ratio, and NA represents the numerical aperture of the image formation device.

Embodiments of the present disclosure, relating to the technical field of projection and display, provide a projection device. The projection device includes a projecting unit, a dust-proof device, and an adjusting unit. The dust-proof device includes a housing, a first light-transmissive plate, and a second light-transmissive plate. The housing is provided with a receiving chamber. The projecting unit is disposed in the dust-proof device, and the dust-proof device achieves a dust-proof function for the projecting unit. In addition, part of the projection light beam of the projecting unit may be emitted from the first light-transmissive plate of the dust-proof device to achieve projection in a first direction, and may be emitted from the second light-transmissive plate to achieve projection in a second direction. The adjusting unit disposed on the dust-proof device may adjust the projection direction of the projection light beam emitted from the second light-transmissive plate to enlarge a projection range in the second direction. According to the embodiments of the present disclosure, multi-direction projection and dust-proofing are implemented.

A parameter adjusting method is applied to a projector having an ambient light sensor, a database and a digital micromirror device. The parameter adjusting method includes analyzing a detection signal generated by the ambient light sensor to acquire an environmental light datum, comparing the environmental light datum with a lookup table of the database to compute at least one compensation parameter, and adjusting an amount of reflection light generated by the digital micromirror device in accordance with the at least one compensation parameter for controlling the projector to output a calibrated projection image in response to compensation of the environmental light datum.

A parameter adjusting method is applied to a projector having an ambient light sensor, a database and a digital micromirror device. The parameter adjusting method includes analyzing a detection signal generated by the ambient light sensor to acquire an environmental light datum, comparing the environmental light datum with a lookup table of the database to compute at least one compensation parameter, and adjusting an amount of reflection light generated by the digital micromirror device in accordance with the at least one compensation parameter for controlling the projector to output a calibrated projection image in response to compensation of the environmental light datum.

An optical assembly includes a first prism and a second prism. The first prism has a first surface. The first surface includes a first optical region. The second prism has a second surface. The first and the second surface are disposed facing each other. The second surface includes a second optical region, in which on a first reference plane, an orthographic projection of the first optical region overlaps an orthographic projection of the second optical region, and the first reference plane is substantially parallel to the first surface or the second surface. When the optical assembly is at a first temperature, at least one of the first optical region and the second optical region is concave, and a vertical distance between the first and the second optical region gradually decreases from a first center point of the first optical region to a first edge of the first optical region.

An optical assembly includes a first prism and a second prism. The first prism has a first surface. The first surface includes a first optical region. The second prism has a second surface. The first and the second surface are disposed facing each other. The second surface includes a second optical region, in which on a first reference plane, an orthographic projection of the first optical region overlaps an orthographic projection of the second optical region, and the first reference plane is substantially parallel to the first surface or the second surface. When the optical assembly is at a first temperature, at least one of the first optical region and the second optical region is concave, and a vertical distance between the first and the second optical region gradually decreases from a first center point of the first optical region to a first edge of the first optical region.

An optical device includes a first optical system having an optical element, a second optical system having a lens and disposed at a reduction side of the first optical system, a first holding member holding the optical device, a second holding member holding the lens, and a movement mechanism configured to move the first holding member in optical axis directions. The optical element has a reflection surface. The first holding member has a first holding portion holding the optical element and a first coupling portion extending from the first holding portion to a second optical system side. The movement mechanism has a transport mechanism configured to move the first coupling portion along the optical axis directions, and a guide mechanism configured to guide the first holding member in the optical axis directions. The guide mechanism restricts rotation of the first holding member around the optical axis.

An optical device includes a first optical system having an optical element, a second optical system having a lens and disposed at a reduction side of the first optical system, a first holding member holding the optical device, a second holding member holding the lens, and a movement mechanism configured to move the first holding member in optical axis directions. The optical element has a reflection surface. The first holding member has a first holding portion holding the optical element and a first coupling portion extending from the first holding portion to a second optical system side. The movement mechanism has a transport mechanism configured to move the first coupling portion along the optical axis directions, and a guide mechanism configured to guide the first holding member in the optical axis directions. The guide mechanism restricts rotation of the first holding member around the optical axis.

A system includes: a phosphor configured to receive first light having a first color, to produce second light having a second color responsive to the first light, and to transmit at least a first portion of the first light; a color wheel comprising a first colored segment configured to transmit light having a third color and a second colored segment configured to transmit light having a fourth color; a light tunnel optically coupled between the phosphor and the color wheel configured to transmit combined light including least a portion of the first light and the second light; wherein the first segment is configured to transmit the third color as first transmitted light and the second segment to transmit light of the fourth color as second transmitted light; and a spatial light modulator configured to modulate the first transmitted light and the second transmitted light.

A system includes: a phosphor configured to receive first light having a first color, to produce second light having a second color responsive to the first light, and to transmit at least a first portion of the first light; a color wheel comprising a first colored segment configured to transmit light having a third color and a second colored segment configured to transmit light having a fourth color; a light tunnel optically coupled between the phosphor and the color wheel configured to transmit combined light including least a portion of the first light and the second light; wherein the first segment is configured to transmit the third color as first transmitted light and the second segment to transmit light of the fourth color as second transmitted light; and a spatial light modulator configured to modulate the first transmitted light and the second transmitted light.