Standard display with individual look
It is not a contradiction in terms: individually designed standard displays for industry. Display production leaves room for maneuver to give standard displays an individual look.
Many medium-sized companies with small to medium-sized production quantities would like to give their product a unique look and thus create a unique selling point compared to the competition. This can also be described as an “affordable design criterion”. The following text uses the example of a standard TFT display to show what current options are available for this.
The technical equipment of the corresponding TFT does not matter, but the appearance in the device and should be in the foreground for the viewer.
From a commercial point of view, it is very difficult for medium-sized companies to adapt a TFT display to the needs of their product. This is reserved for large customers, as very high development and modification costs must be expected. The initialization costs are only amortized over very large quantities. Nevertheless, there are ways and means of giving the electronic display a distinctive appearance. A first and effective means for this is the protective or cover glass.
What is important for cover glasses?
Applied to protect the touchscreen or the display from mechanical stress, as well as in harsh environments, protective glasses, also known as cover lenses, are made of extremely impact-resistant quartz glass (borosilicate glass) and are initially transparent from glass production. The choice of glass thickness depends on the area of application of the product and the resulting requirements for its resistance. Protective glasses are offered in thicknesses of around 1.1 to 8.0 mm. If the end device is subject to testing and is subject to the DIN standard, the thickness of the glass to be selected results from the requirements of the tests for mechanical strength prescribed in the DIN standard. Depending on the type of use of the product, a distinction is made between shock, drop and impact tests, as well as tests to reduce stresses in the molded part.
Individual Print on the cover glass
The main focus of the tests is essentially directed against the risk of injury from glass cracks or flaws for the user. Protective glasses take on other important tasks by antireflecting their surface and by applying UV protective layers.
The blank is printed from the rear outside the active display area. Black printing extends to the outer edges of the glass. For example, a company logo or other product specifics can be applied to the black edge area of the protective glass. In practice, this is done by printing the icon in a first step. Then the black printing takes place across the board.
Colors for printing
When choosing the color, it is important to note that quartz glasses do not offer one hundred percent transparency, but rather go in the direction of smoked glass, i.e. tend towards gray. Very intense colors can appear paler and slightly darker in reality. In individual cases, the desired color decides on the implementation of the CI specifications. In general, other muted colors can also be used as the basic printing, it does not always have to be black.
For good economy, however, colors from the “non-metallic area” should be given preference. In Europe, colors are often specified in the RAL color system. Not so in Asia, where the Pantone color system usually applies. In many years of cooperation with Chinese manufacturers, a defined Pantone color value has proven to be the least ambiguous information for production. Nowadays, the cover glasses are made using a laser cutting process and are no longer broken as in the past.
Free choice of shape for the glasses
Laser-cut glasses allow any shape: Away from the purely square covers to freely definable shapes. It is a good recommendation not to adjust the size of the cover glass closely to the TFT dimensions. In the event of a discontinuation, the new TFT can be more easily adapted to the existing cover glass.
In addition, it is advisable to select the TFT housing cutout to be larger in order to be better prepared for changes in the future. In many developments, the cover glass was enlarged far beyond the pure display dimensions. The area gained in this way can be used as a functional area for switching units, pushbuttons, status indicators (LED) or encoders.
For interaction with the product, displays have long been the interface between people and machines (HMI). So why not bring functional elements to the outside on the glass surface? In the interests of user-friendly and intuitive operator guidance.
The bonding process depends on the application
Experience has shown that the touch sensor and the protective glass form a unit for a visually better function. The optimal bonding process depends on the application: It depends on the product-specific operating requirements and the application environment. Should the HMI be operated with gloves or should it be protected from moisture? Illuminated switch buttons (elastomers) can also be integrated into the protective glass.
All switching elements come moisture-proof, flat and, if desired, with their own LED lighting in a protective glass. Furthermore, freely plannable holes in the diameter are possible in the protective glass and serve, for example, as a passage for an encoder installed in the device.
Resolution, contrast and readability
For industrial applications, TFTs will play an important role for many years. In current projects, the focus is on higher resolution and contrast values as well as good readability. In addition, optimal and interactive operator guidance is becoming more important. The selection of the right TFT is crucial for the long product life cycles required in industry.
In the phalanx of the TFT displays produced, some sizes have emerged as the standard as a result of high acceptance on the world market.
RGB, LVDS and MIPI are available for the most frequently used interfaces for TFTs. For larger TFTs or to display HD images, the DisplayPort (DP) is more important than HDMI as an interface that is not license-dependent. Even simple segment displays can be implemented inexpensively in an adapted application. This can be, for example, the presentation of the display contents in negative representation with white text on a black background.