{"id":16309,"date":"2026-10-24T15:31:59","date_gmt":"2026-10-24T15:31:59","guid":{"rendered":"https:\/\/rjoytek.com\/"},"modified":"2026-10-27T08:10:38","modified_gmt":"2026-10-27T08:10:38","slug":"wie-die-pixel-in-einem-lcd-mit-strom-versorgt-werden","status":"publish","type":"post","link":"https:\/\/rjoytek.com\/de\/wie-die-pixel-in-einem-lcd-mit-strom-versorgt-werden\/","title":{"rendered":"Wie die Pixel in einem LCD mit Strom versorgt werden"},"content":{"rendered":"

The pixels in a typical TFT LCD are controlled by electrical voltages delivered through rows and columns on the panel. Each color subpixel has a thin-film transistor (TFT) that acts as a switch. When its row is selected, the TFT allows a data voltage to charge the pixel electrode. The resulting voltage across the liquid-crystal cell changes how that subpixel controls light.<\/p>\n

The subpixel is not a tiny light bulb. In a transmissive LCD, a separate backlight supplies the light, while the liquid-crystal cell and polarizers regulate it. This distinction is useful when an LCD lights up but does not show the expected image: illumination and image control are related, but they are separate functions.<\/p>\n

What is being powered in an LCD pixel?<\/h2>\n
\"Conceptual
Conceptual illustration; not a microscope image or a specified pixel layout.<\/figcaption><\/figure>\n

A color LCD pixel commonly contains red, green and blue subpixels. In a typical active-matrix TFT panel, each subpixel has its own switching transistor and electrode. The liquid-crystal cell behaves electrically like a capacitance; a storage capacitor helps hold the pixel state between updates. The actual structure and driver integration depend on the panel.[1]<\/a><\/sup><\/p>\n

The important quantity for the liquid crystal is the voltage across the cell: the difference between the pixel-electrode potential and the relevant common-electrode reference. This creates an electric field in the liquid-crystal layer. Together with the panel’s optical arrangement, that field changes how much light reaches the viewer.<\/p>\n

Drivers, timing circuits and bias supplies need power to create and update those voltages. Depending on the module, some of those circuits are integrated on the glass or flexible circuit; others may be supplied externally. The panel datasheet determines what the host must provide.<\/p>\n

How row and column drivers update a subpixel<\/h2>\n
\"Display
Conceptual system view; it does not show the internal pixel circuit or prove board compatibility.<\/figcaption><\/figure>\n

Pixels are organized in a matrix. Gate lines select rows of TFT switches, and data lines carry the values used to set the subpixel voltages. A timing controller coordinates the drivers and the incoming image information.<\/p>\n

  1. The gate driver selects a row, turning on the TFT switches for that row.<\/li>
  2. The source driver presents the required data voltages on the column lines.<\/li>
  3. With the switches on, the selected pixel electrodes and associated capacitances charge toward the applied values.<\/li>
  4. The gate driver deselects the row. The switches turn off, and the stored charge helps maintain the states while other rows are addressed.<\/li>
  5. The process repeats as the panel updates the image.<\/li><\/ol>\n

    These steps describe a common TFT active-matrix arrangement. The source driver updates the columns of a selected row together; the panel does not need a separate external wire from the host to every individual subpixel. Texas Instruments describes this row-and-column addressing and the role of the timing controller in its display fundamentals material.[2]<\/a><\/sup><\/p>\n

    Charge is not held perfectly. Leakage and other circuit effects change the voltage over time, which is why the panel’s driving scheme refreshes the pixel states. The required timing and waveform belong to the particular panel design.<\/p>\n

    What do VGH, VGL, AVDD and VCOM do?<\/h2>\n

    These labels appear in many TFT LCD designs, but they are not a universal pinout or a set of values to apply to an unknown module.<\/p>\n
    Signal or supply<\/th>Typical role<\/th>What to check<\/th><\/tr><\/thead>
    VGH and VGL<\/td>Gate-driver levels used to turn TFT switches on and off.<\/td>Whether the module generates them internally and what its datasheet specifies.<\/td><\/tr>
    AVDD<\/td>An analog supply used by relevant display-driver circuits in some designs.<\/td>The actual supply range and the panel’s power architecture.<\/td><\/tr>
    VCOM<\/td>A common-electrode reference used in many panel-driving arrangements.<\/td>The specified reference, waveform and adjustment method, if accessible.<\/td><\/tr>
    Logic supply<\/td>Power for controller and interface logic.<\/td>The module’s voltage, current and sequencing requirements.<\/td><\/tr>
    Backlight supply<\/td>Power for the light source in a transmissive module.<\/td>LED configuration, drive current and dimming requirements.<\/td><\/tr><\/tbody><\/table>\n

    Gate levels control the switches; the source-driver voltage sets the pixel-electrode state. VCOM provides a reference used by the panel’s drive scheme. The arrangement can differ across products, and some rails may never be exposed at the connector. Do not infer their values from another LCD or power a pin based only on a familiar name.[1]<\/a><\/sup><\/p>\n

    Why does the pixel voltage change polarity?<\/h2>\n

    LCD driving commonly alternates the polarity of the voltage across the liquid-crystal cell relative to its reference. This is called inversion<\/strong>. The technique helps limit an unwanted long-term DC component across the cell and the image-quality problems associated with it.<\/p>\n

    Inversion can follow different patterns, such as frame, line or other arrangements, according to the panel design. It does not mean that the visible picture must alternate between positive and negative images. The optical result depends on the magnitude of the intended drive and the specific LCD mode. Follow the manufacturer’s specified driving scheme rather than modifying VCOM or inversion settings by guesswork.[3]<\/a><\/sup><\/p>\n

    How does a voltage become a visible color?<\/h2>\n

    In a common transmissive color TFT LCD, the backlight illuminates the panel. The liquid-crystal and polarizer stack controls light through each subpixel, and color filters provide red, green and blue regions. By setting the subpixel states, the driver produces the intended combination of light levels.<\/p>\n

    More voltage does not always mean more light. Whether a given voltage makes a cell appear brighter or darker depends on the optical mode and configuration. Gamma settings and the panel’s voltage-to-light response also affect the displayed grayscale. A panel’s brightness and color cannot be determined from the supply labels alone.<\/p>\n

    Why a lit backlight does not prove the pixels are working<\/h2>\n
    \"Separate
    Conceptual assembly; layers and construction vary by module.<\/figcaption><\/figure>\n

    A white or illuminated screen shows that some light is reaching the viewer. It does not establish that the panel logic is powered correctly, the source and gate drivers are operating, or the input image is valid. A missing backlight can likewise hide an otherwise active image.<\/p>\n

    For a specific module, review the documented logic supply, reset and initialization sequence, input interface, timing, connector pinout and backlight drive. Check the module and controller documentation before measuring or changing any rail. Similar symptoms can have several causes, so use the observations to guide testing rather than treating screen color as a diagnosis.<\/p>\n

    Resolution and connector shape are not enough to establish controller-board compatibility. The review also needs the panel model, interface, pin definition, timing, driver IC when available, backlight and touch requirements, firmware, operating system and use environment. An HDMI-to-MIPI solution may need active conversion and panel-specific configuration.<\/p>\n

    Frequently asked questions<\/h2>\n

    Does each LCD pixel emit its own light?<\/h3>\n

    No. LCD pixels control light through the optical stack. A transmissive LCD uses a separate light source, commonly a backlight.<\/p>\n

    Does each subpixel have its own power wire from the host?<\/h3>\n

    No. A typical TFT active matrix uses shared row and column lines and switching transistors to address subpixels.<\/p>\n

    What holds the pixel state between updates?<\/h3>\n

    The liquid-crystal cell and associated storage capacitance retain charge after the TFT switch turns off. The charge is refreshed according to the panel’s drive scheme.<\/p>\n

    Can I apply a fixed DC voltage to an LCD pixel?<\/h3>\n

    Do not substitute an arbitrary DC drive for the manufacturer’s specified waveform. Typical panel driving uses polarity inversion to limit unwanted DC bias across the liquid-crystal cell.<\/p>\n

    From pixel driving to a working display<\/h2>\n

    A TFT LCD image depends on coordinated row selection, data voltages, a common reference and an appropriate optical system. For an actual module, start with its datasheet and the matching controller documentation. Review the related TFT structure and driving guide<\/a> for broader panel context, or contact RJY Display<\/a> with your panel and system requirements.<\/p>\n

    References<\/h2>\n
    1. Texas Instruments, Powering automotive displays to create interactive driving experiences<\/a>, explanation of TFT subpixels, drive voltages and VCOM.<\/li>
    2. Texas Instruments, Understanding Basic Components Working Together in LCD Displays<\/a>.<\/li>
    3. Texas Instruments, LCD physical and electrical driving principles<\/a>.<\/li><\/ol>\n","protected":false},"excerpt":{"rendered":"

      Erfahren Sie, wie TFT-LCD-Zeilen- und Spaltentreiber die Pixelspannungen einstellen, warum die Polarit\u00e4t invertiert wird und wie sich die Hintergrundbeleuchtung von der Pixelsteuerung unterscheidet.<\/p>","protected":false},"author":1,"featured_media":16305,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-16309","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-knowledge"],"_links":{"self":[{"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/posts\/16309","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/comments?post=16309"}],"version-history":[{"count":1,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/posts\/16309\/revisions"}],"predecessor-version":[{"id":16315,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/posts\/16309\/revisions\/16315"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/media\/16305"}],"wp:attachment":[{"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/media?parent=16309"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/categories?post=16309"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rjoytek.com\/de\/wp-json\/wp\/v2\/tags?post=16309"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}