JVC 330, 370 SC Optical Section, CRT Assembly, Relay Lens, Image Light Amplifier ILA Assembly

Chapter 2—Functional Descriptions

Figure 2-18Backplane Interface Block Diagram

2.7 Optical Section

The Optical section consists of the CRT Assembly, the Arc Lamp Assembly, and the Optical subassemblies, which provides the image to be viewed on the screen. The Optical Section filters, splits and directs the high intensity light to the three

(3)separate (RGB) light channels. Figure 2-19 shows the video path from the CRT to the screen and the optical path from the Arc Lamp to the screen.

CRT Assembly

The image in the projector begins at the three (3) CRTs. The CRT Assembly is located beneath the main electronics card cage and contains three (3) sets of the following:

CRT tubes.

CRT cooling assemblies.

CRT Yokes.

Yoke clamps.

Video Amplifier Boards.

Each CRT has a high resolution infrared beam and a high resolution phosphor screen. Fans mounted at the rear of the assembly cool the CRT Assembly. Procedures for adjusting the yokes and the width coils can be found in Section.3.2. A functional description of the Video Amplifier Boards is provided in Section 2.6.5.

Relay Lens

The relay lens picks up the CRT image from the face of the CRT and focuses the image to the ILA® assembly.

Image Light Amplifier (ILA® ) Assembly

At the same time as the image is received at the input side of the ILA® assembly, the output side of the ILA® assembly is receiving high intensity light from the arc lamp through the prism. This high intensity light is then phase modulated (altered) by the video signal from the input side of the ILA® assembly and then reflected back out of the output side and then travels through the prism to be picked up by the projection lens.

NOTE: The prism reflects horizontally polarized light and passes vertically polarized light. Light from the arc lamp is polarized horizontally and reflects from the prism into the ILA® assembly then back out again, after being phase modulated 90° to vertical by the Liquid Crystal layers into vertically polarized

2-72 Model 330. 340SC, and 370SC Service Manual