What is the weight of a 2.76 inch 480x480 round TFT display?

The weight of a typical 2.76 inch 480x480 round TFT display module is approximately 12.5 grams to 15 grams, depending on the specific construction, backlight type, and whether it includes a touch panel or not. For a standard model without capacitive touch, such as the 2.76 inch 480x480 round tft display from DisplayModule, the weight is around 13.2 grams. This is based on the glass substrate thickness (typically 0.4mm to 0.5mm), the polarizer layers, the driver IC, and the flexible PCB (FPC) tail. The backlight, usually a white LED array with a light guide plate (LGP), adds about 2 to 3 grams. If you opt for a variant with a PCAP (projected capacitive) touch panel, the weight increases by 4 to 6 grams due to the additional glass or film layer and the touch controller IC. So, a full module with touch can weigh up to 19 grams.

To give you a more granular breakdown, let’s look at the physical components. The active area of the display is circular, with a diameter of 2.76 inches (70.1 mm). The glass itself is a single sheet of amorphous silicon TFT glass, typically 0.5mm thick. Using the density of display glass (around 2.5 g/cm³), the glass alone weighs about 4.8 grams. The polarizer films (top and bottom) add 0.5 grams combined. The driver IC, often a COG (chip-on-glass) type like the ST7701S or GC9A01, is negligible in weight (less than 0.1 gram). The FPC, which is usually 0.2mm thick and about 30mm long, weighs about 0.3 grams. The backlight unit, consisting of a 0.4mm thick LGP, a reflective sheet, and 6 to 8 side-view LEDs, weighs around 2.5 grams. The bezel or frame, if present (some modules use a metal or plastic bracket), can add another 1 to 2 grams. So, the total for a bare module is around 8 to 10 grams, but the actual product weight is higher because of the protective cover glass (often 0.7mm thick) and the adhesive layers used in lamination.

Let’s compare this with other round displays in the same size range. For example, a 2.8 inch round TFT with 240x240 resolution (like the GC9A01-based modules) typically weighs 10 to 11 grams because it has a lower resolution and fewer data lines, leading to a simpler FPC. A 2.4 inch round TFT with 240x240 resolution weighs around 8.5 grams. The 2.76 inch 480x480 round TFT is heavier because it has four times the pixel count (480x480 vs 240x240), which requires a more complex driver IC with more outputs, a denser FPC with more traces, and a higher-quality backlight to maintain brightness uniformity across the higher resolution. The MIPI interface also adds to the FPC complexity, as it requires differential pairs for data lines, which increases the copper weight and the overall FPC thickness.

Now, let’s talk about the impact of the backlight on weight. The 2.76 inch 480x480 round TFT typically uses a white LED backlight with a brightness of 300 to 400 nits. The LED count is usually 6 to 8, each weighing about 0.05 grams. The LGP is made of PMMA (acrylic), which has a density of 1.18 g/cm³. For a circular LGP with a diameter of 70mm and a thickness of 0.4mm, the volume is about 1.54 cm³, giving a weight of 1.82 grams. The reflective sheet (white PET) adds 0.3 grams, and the diffuser film adds 0.2 grams. So, the entire backlight unit is about 2.5 to 3 grams. If the display has a higher brightness (e.g., 600 nits for outdoor use), the LED count may increase to 10 or 12, and the LGP may be thicker (0.6mm), pushing the backlight weight to 4.5 grams.

Another factor is the cover glass. Many round TFT modules come with a circular cover glass that is pre-laminated to the display. This cover glass is typically 0.7mm thick and made of tempered glass with a density of 2.5 g/cm³. For a 70mm diameter circle, the cover glass weighs about 6.7 grams. Add the OCA (optically clear adhesive) layer, which is about 0.1mm thick and weighs 0.2 grams. So, a module with a cover glass can weigh 20 to 22 grams total. Some manufacturers offer a thinner cover glass (0.4mm) to reduce weight, but this is less common for round displays due to the risk of breakage during handling.

Let’s look at the connector and FPC weight. The FPC on the 2.76 inch 480x480 round TFT is usually a 0.2mm thick polyimide-based flex circuit with a length of 20 to 30mm and a width of 10 to 15mm. The copper traces are typically 1 oz (35 µm) thick. The weight of the FPC is about 0.3 to 0.5 grams. The connector (e.g., a 0.5mm pitch FPC connector) adds 0.1 grams. If the display has a ZIF connector, it adds another 0.05 grams. Some modules have a longer FPC (e.g., 50mm) for easier integration, which increases the weight by 0.2 grams. The driver IC, if it is a COG type, is mounted directly on the glass, so it does not add extra weight beyond the silicon die (which is about 0.01 grams). However, if the driver IC is on a separate PCB (like in some older designs), the weight increases significantly.

Now, let’s consider the touch panel. A PCAP touch panel for a 2.76 inch round display typically uses a glass sensor with a thickness of 0.4mm to 0.7mm. The sensor layer is made of ITO (indium tin oxide) on a glass substrate. The weight of a 0.4mm thick glass sensor for a 70mm diameter circle is about 3.8 grams. The touch controller IC (e.g., FT6336 or CST816) is mounted on a small FPC, adding 0.2 grams. The total touch panel weight is 4 to 5 grams. If the touch panel is a film-type (e.g., using PET substrate), the weight is lower, around 2 to 3 grams, but film-type touch panels are less common for round displays due to durability concerns. So, a full module with touch can weigh 17 to 19 grams, depending on the touch technology.

Here is a table summarizing the weight breakdown for different configurations of the 2.76 inch 480x480 round TFT display:

From a practical standpoint, the weight of the 2.76 inch 480x480 round TFT display matters for applications like smartwatches, smart rings, or portable medical devices where every gram counts. For example, a smartwatch with a 2.76 inch display typically has a total weight of 40 to 60 grams, so the display itself accounts for 25% to 35% of the total weight. If you are designing a lightweight device, you might want to avoid the cover glass and use a thinner backlight (e.g., 0.3mm LGP) to save 2 to 3 grams. However, this can reduce brightness and durability. Some manufacturers offer a custom version with a thinner glass (0.4mm) and a reduced backlight LED count (4 LEDs) to achieve a total weight of 8 grams for the bare module, but this is not standard.

The weight also affects the mechanical design. A heavier display requires stronger mounting brackets and more robust adhesive (e.g., VHB tape or epoxy) to prevent it from shifting during vibration or drop testing. For automotive applications, the display must withstand 10G vibration, so the weight must be considered in the mounting design. The center of gravity of the display is at the center of the circle, which is important for balancing in wearable devices. If the display is too heavy, it can cause the device to tilt on the wrist, leading to discomfort.

Let’s look at the specific product from DisplayModule. The DM-TFT28-479 is a 2.76 inch round TFT with 480x480 resolution, using a MIPI interface (2-lane) and a driver IC (ST7701S). The module includes a 0.5mm thick TFT glass, a 0.4mm thick backlight with 6 LEDs (brightness 350 nits), and a 0.2mm thick FPC with a 0.5mm pitch connector. The weight of this module, as per the datasheet, is 13.2 grams. This is consistent with the breakdown above, assuming a bare module without a cover glass or touch panel. If you add the optional cover glass (which is available separately), the weight increases to 20 grams. The module also has a metal bezel that adds 1.5 grams, which is included in the 13.2 grams. So, the actual glass weight is 11.7 grams, and the bezel is 1.5 grams.

For comparison, let’s look at other round displays in the same product line. The 2.8 inch round TFT from the same manufacturer (DM-TFT28-478) with 240x240 resolution weighs 10.5 grams, which is 2.7 grams lighter. The difference comes from the lower resolution (fewer data lines on the FPC) and a simpler driver IC (GC9A01, which is smaller and lighter). The 2.4 inch round TFT (DM-TFT24-456) with 240x240 resolution weighs 8.2 grams. So, the 2.76 inch 480x480 round TFT is 60% heavier than the 2.4 inch version, even though the diameter is only 15% larger. This is because the pixel density is higher (480x480 in a 2.76 inch circle gives 208 PPI, while 240x240 in a 2.4 inch circle gives 141 PPI), requiring more complex electronics.

Another important factor is the interface. The MIPI interface used in the 2.76 inch 480x480 round TFT requires a differential pair for each data lane, which increases the number of traces on the FPC. For a 2-lane MIPI, you need 4 data lines (2 pairs) plus a clock pair, plus control signals, totaling about 12 to 15 traces. This makes the FPC wider and heavier. In contrast, a SPI interface (used in lower-resolution round displays) requires only 4 to 6 traces, so the FPC is narrower and lighter. The MIPI FPC also has a higher impedance control requirement, which often means thicker copper (1.5 oz) and more shielding, adding 0.1 to 0.2 grams.

Let’s talk about the backlight current and its impact on weight. The backlight in the 2.76 inch round TFT typically draws 20 to 30 mA at 3.3V, which is about 66 to 99 mW. The LEDs are usually side-view type with a size of 2.0x1.0mm, each weighing 0.05 grams. The LGP is made of high-transmittance PMMA with a thickness of 0.4mm. Some manufacturers use a thinner LGP (0.3mm) to reduce weight, but this reduces the light uniformity and can cause hot spots. The diffuser film is typically 0.1mm thick and adds 0.2 grams. The reflective sheet is 0.05mm thick and adds 0.1 grams. So, the total backlight weight is 2.5 grams for a standard design. If you want a higher brightness (e.g., 600 nits), you might use 8 LEDs and a thicker LGP (0.5mm), increasing the weight to 3.5 grams. Some modules use a single LED with a large LGP, but this is not common for round displays because the circular shape makes it difficult to achieve uniform brightness with a single LED.

Now, let’s consider the environmental factors. The weight of the display can change slightly with temperature and humidity because the materials expand or absorb moisture. For example, the FPC can absorb up to 0.5% moisture by weight in high humidity (85% RH), adding 0.002 grams. The polarizer films can also absorb moisture, but the effect is negligible. The glass itself does not change weight. So, the weight variation is less than 0.1 gram under normal operating conditions. For precision applications like aerospace, this is not a concern.

Let’s look at the packaging weight. When you buy the 2.76 inch 480x480 round TFT display, it comes in a tray or a box with ESD foam. The packaging adds about 10 to 20 grams, but this is not part of the display weight. The shipping weight of a single unit is typically 30 to 40 grams, including the box. For bulk orders, the weight per unit is lower because the packaging is shared.

From a manufacturing perspective, the weight of the display affects the cost of shipping. For example, if you order 1000 units, the total weight is 13.2 kg (without packaging) or 30 kg (with packaging). Shipping costs are usually calculated by weight, so a lighter display saves money. Some manufacturers offer a lightweight version with a thinner glass (0.4mm) and a reduced backlight (4 LEDs) to achieve a weight of 10 grams, but this is a custom order and may have a longer lead time.

Let’s compare the weight of the 2.76 inch round TFT with other display technologies. An OLED round display of the same size (e.g., 2.8 inch round OLED) typically weighs 8 to 10 grams because it does not need a backlight. The OLED panel is self-emissive, so it has no LGP, LEDs, or diffuser films. The glass substrate is also thinner (0.4mm) because the OLED layers are thinner. However, OLED displays are more expensive and have lower brightness (typically 200 nits) compared to TFT (300 to 400 nits). For applications where weight is critical, OLED might be a better choice, but for cost-sensitive projects, TFT is preferred.

Another comparison is with e-paper displays. A 2.7 inch round e-paper display (like the one from Pervasive Displays) weighs about 12 grams, which is similar to the TFT. But e-paper has a lower refresh rate and is monochrome, so it is not suitable for video applications. The TFT is better for real-time graphics.

Let’s look at the mechanical integration. The weight of the display influences the choice of adhesive. For a 13.2 gram display, you can use a double-sided tape with a peel strength of 10 N/cm to hold it in place. For a 20 gram display with a cover glass, you need a stronger adhesive,