The chassis in the HDLP50W151 is made up of seven (7) major modules. These include the “AC In” CBA that contains the Standby and Run power supplies. The “Audio” CBA, which processes all audio signals. The “A/V In/Out” CBA has the in/out jacks and also does all the video and audio switching. The fourth is the “Formatter” circuit board and it is responsible for converting the video signals into a format that the light engine can use. The fifth is the “DM2CR” which contains the ATSC tuner, NTSC tuner and the QAM digital cable decoder. The DM2CR also serves as the system control for the instrument. The sixth module is the light engine and seven is the lamp power supply.
LIGHT ENGINE ASSEMBLY
CHASSIS OVERVIEW
There are five (5) major circuit boards in the HDLP50W151 chassis (minus the light engine). These include the “AC In” CBA, “Audio” processing CBA, the “DM2CR”, the “A/V In/Out” CBA and the “Formatter” CBA.
The AC In CBA provides the Standby DC power and the Run supply DC power. Both power supplies are switch mode power supplies and are very similar.
The main difference is that the run supply has an on/off circuit that is controlled by the system control micro in the DM2CR.
An AC doubler on the AC In CBA is used to generate power for the lamp power supply.
A valuable troubleshooting tip is to listen for the lamp power supply relay click when AC is plugged in. Since the relay is power by the +12VS source, if the relay doesn't click this is a good indication the standby power supply is inoperative.
The Audio CBA is responsible for final processing of all base band audio signals. This includes volume, equalization, balance and Surround Sound. The audio output power amplifiers that drive the internal speakers are also located on the Audio CBA. Audio for the audio out jacks as well as the FAV (Front Audio Video) circuit are supplied by the Audio CBA. Power (+/-21V) for the Audio CBA is provided by the standby supply.
The DM2CR module contains an NTSC and ATSC tuner section as well as the NTSC PIP tuner. The tuners are capable of processing both digital and analog RF signals (ATSC & NTSC) from either terrestrial or cable sources. The DM2CR is also 256QAM digital cable compatible. The DM2CR has 2 DTV Link connectors which are a compressed digital video inputs offering an IEEE-1394 type video connection for consumer devices such as satellite receivers, cable receivers, and digital recorders that meet the CEA specifications for DTV Link. DTV Link is better known as 1394 or FireWire for digital televisions. Audio and video information is carried on a single wire.
The DM2CR module performs the NTSC decoding of component, SVHS, and composite video signals. The DM2CR also recovers the teletext, closed caption and GemStar data signals that accompany any input video.
All 1H video inputs (NTSC) including signals from the A/V In/Out circuit board are up-converted to 2H by the DM2CR. The video output to the formatter CBA
is YPrPb component. Any 2H component (YPrPb) that is input to the A/V In/Out CBA is routed directly to the formatter.
The audio and video in/out jacks are located on the A/V In/Out CBA. The A/V CBA also provides audio and video switching for external video and audio signals. The auto detected 1H and 2H video signal are routed via the A/V In/Out circuit board. The 1H and 2H NTSC is routed to the DM2CR for up-conversion. Any 2H component external video signal is routed directly to the formatter circuit for final processing.
The formatter circuit board is responsible for converting the analog video from either the DM2CR or the analog inputs from the A/V In/Out circuit board into a format that is compatible with the light engine. All functions and circuits on the formatter circuit board is monitored and controlled by the system control
Microcomputer in the DM2CR module. This is accomplished via the RUN 2 I2C clock and data bus. The same I2C bus is also routed through the formatter board to the light engine. The 2H and 2.14H external video inputs are applied to the formatter circuit board (via connector BV402) where it is applied to the BEP (back end processor) for processing into an analog RGB signal. The NTSC and the ATSC analog video signal (2H) from the DM2CR is also input to the formatter (via connector BV401). The video is applied to IV401 for conversion to RGB. The RGB output from IV401 is then applied to the Digital Signal processing circuits where it is digitized and output to the light engine as DVI (Digital Video Interface).
MMD [DLP] TECHNOLOGY
Texas Instruments Digital Light Processing (DLP) technology provides an all digital projection display that offers superior picture quality in terms of resolution, brightness, contrast, and color fidelity. The DLP device consists of an array of movable mcromirrors. Each mirror is independently controllable and is used to modulate reflected light. The mirror is controlled by loading data into the memory cell located below the mirror. The data electrostatically controls the mirror’s tilt angle which controls whether passes through the projection lens and onto a screen or reflected away.
Until recently, light-valve technologies for projection display applications have been unable to take full advantage of the economies and stability offered by the digital revolution. Increasing digital content has been incorporated into the transmission and signal processing chain from source material to the projection display light valve. Ultimately, however, the light valve itself is analog in nature and subject to analog limitations. The possibility of an all-digital (source-to-eye) display was realized in 1987 with the invention of the DLP device at Texas Instruments. The DMD is an array of fast digital micromirrors, monolithically integrated onto and controlled by a memory chip.
Digital Light Processing (DLP) systems present bright, seamless images to the eye, with the characteristics that we have come to expect from digital technology, namely high image fidelity and stability. DLP-based displays exhibit no lag or smearing of the image from one digital frame to the next. The first DLP-based projection display products were introduced to the market in April 1996.
DISPLAY OPERATION
Each digital light switch of the DMD is an aluminum micromirror, 16 micrometer square, that can reflect light in one of two directions, depending on the state of an underlying memory cell. The mirror is rotated by electrostatic attraction produced by voltage differences developed across an air gap between the mirror and the memory cell. The mirror rotation is limited by mechanical stops to ±10 degrees. With the DLP cell in the on state, the mirror rotates to +10 degrees. With the DLP cell in the off state, the mirror rotates 10 degrees.
DLP DEVICE
DLP CELL TECHNOLOGY
When we combine the DLP device with a suitable light source and projection optics, the mirror reflects incident light either into or out of the projection lens by a simple beam-steering action. Thus, the on state of the mirror appears bright and the off state of the mirror appears dark. The fast switching time of the mirrors enables the use of a pulse width modulation technique for the production of gray scale. The DLP device accepts electrical words representing gray levels of brightness at its input and then outputs digital light as optical words to the eye. Because of the short pulse duration, the optical words are interpreted by the eye of the observer as analog light containing up to one billion or more color and gray scale combinations per pixel. Furthermore, the fast switching time results in a lag free image. Digital light is accurate because the light pulse durations are determined by the precise division of time. The resulting projected image faithfully reproduces the original source material and the image is stable, independent of temperature or age of the projector, and is free from photo degradation effects, even up to brightness levels necessary for electronic cinema. The tiny gaps between the mirrors diminish objectionable pixilation effects and create a seamless image that has long been the hallmark of DMD-based projection displays.