BenQ 2720S, Service Manual

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The optics process can be divided into three steps in detail: light source,
imaging and receiving. The light path diagram is shown in Figure 4-2. And
the three steps will be described in the following:
Figure 4-2 Diagram of Light Path
4.1.1 Light Source
Using a lamp to be the light source here. Reflect plate is a tool that used
to increase light intensity. Applying light to go through the object and the
non-reflected light will pass through window cover, lens, and finally forms
an image on color CCD. If the intensity of light is too low, the color CCD
can't work precisely. Please replace a new lamp under this situation.
4.1.2 Imaging
It gets an image by lens in this step, and the diagram is shown in Figure
4-3. The light of the object passing through this lens to form an image on
the CCD, and the magnification (M) equals image distance (q) divided by
object distance (p), i.e., M= q / p. From Fig.4-4, we can get the paraxial
formula about lens focus (f), object distance (p) and image distance (q).
The formula describes relation between lens focus (f), object distance (p),
and image distance (q) as 1/f = 1/p +1/q.
4-6 API Confidential Mechanism
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