Projectors and Screens

Question 1

Screen Gain (2)

Answer 1

• the ability of a screen to redirect light energy in a narrower viewing area, making projected images appear brighter to viewers sitting on the axis to the screen
• The higher the gain number of a screen, the narrower the viewing angle over which it provides optimal brightness

Question 2

matte white screen (5)

Answer 2

• diffuses light uniformly in both horizontal and vertical planes
• creates a wide viewing area, which can be up to 180 degrees in both axes
• good color rendition
• can be the best choice for projection applications with sufficiently bright projectors
• Light from the projector is diffused, scattered in all directions, evenly

Question 3

Ambient light rejection (4)

Answer 3

• generally increases as the gain of the screen increases
• as the screen gain increases, the angle at which light hits the screen becomes more important
• Ambient light that is not on axis with the projector and viewer is reflected away from the viewer
• makes the screen appear darker, increasing the contrast ratio.

Question 4

high-gain screen (4)

Answer 4

• If the ambient light is too high and/or not controllable
• directs most of the light energy from the projector away from the direction of the audience
• screen will be more tolerant of high ambient light conditions because any ambient light that hits the screen can be directed away from the audience
• angle of incidence equals angle of reflection

Question 5

Hot Spot

Answer 5

• one of the trade-offs for screen gain in front projection and some rear projection screens
• most noticeable when viewing the projected image off-axis.

Question 6

Inverse Square Law

Answer 6

When you increase projection distance in an effort to create a larger image, the larger image is not as bright.

Question 7

Front Projection Pros (2)

Answer 7

• Less space required than with rear projection

- Simplified equipment placement

Question 8

Front Projection Cons (3)

Answer 8

• Problematic ambient noise from cooling fans in projector
• Image can be blocked by walking in front of a projector
• Presenter may look directly into a bright light source

Question 9

Angularly Reflective Screens

Answer 9

Light from the projector is reflected back at the same angle that it strikes the screen

Question 10

Rear Projection Pros (2)

Answer 10

• Provides better contrast and color saturation in environments with high ambient light
• Noise created from projector not an issue

Question 11

Rear Projection Cons (2)

Answer 11

• Requires more space for installation

- More expensive than front projection due to amount of space required

Question 12

Diffusion Screen Material (6)

Answer 12

• The screen substructure may be rigid acrylic, glass or for portable applications, a vinyl fabric
• provides a diffused, coated or frosted surface on which the image is focused
• provides a wide viewing angle both horizontally and vertically but with little or no gain
• may be some hot spotting due to the transparency of the screen fabric, depending on the vertical placement of the projector with relationship to the audience
• light from the projector is transmitted through the screen with relatively little refraction
• ambient light rejection of this material is moderate and is based on the viewer-side material’s reflectivity or sheen.

Question 13

Optical Screen Material (3)

Answer 13

• used in most permanent rear screen applications
• screen system is made up of a series of lenses formed into the screen material
• Most common is the two-lens system.

Question 14

Screen Selection (7)

Answer 14

• screen surface
• ambient light rejection
• front or rear projector orientation.
• the audience
• media format
• room size
• content of the presentation