Advanced graphic control technology for high resolution bar type displays in HMI applications

Author : David Wang | System Development Engineer | Bridgetek

01 August 2021

Figure 1. Car dashboard display with 1440 x 540 pixel resolution
Figure 1. Car dashboard display with 1440 x 540 pixel resolution

As David Wang, System Development Engineer at display specialist, Bridgetek explains here, bar type displays are widely used to provide human machine interfaces (HMIs) across a range of industry sectors – being especially applicable to use cases where there is limited space available, or with stringent budgetary constraints.

This article was originally featured in the August 2021 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.

Consuming markedly less power than squarer displays of similar width, such displays are also appealing from an energy saving perspective, so battery-operated portable equipment will often feature them.  In addition, bar type display deployments suit upgrading of existing equipment designs that are migrating from mechanical buttons and 7-segment displays to more sophisticated HMI arrangements, as layout fewer changes are necessary.

Among numerous places where they are regularly seen is in domestic appliances, smart home controls, sporting equipment, healthcare monitoring systems, digital signage and point of sale (PoS) units. They are also commonly used in vehicles’ digital dashboards. In some cases, partitioning is employed, so that several squarer display sections dealing with different functional aspects can be accommodated on a single bar.

Though bar type displays offer size, cost and integration advantages, the way that their graphics are rendered is not without challenges. Here, we will look at what can be done to address challenges of this kind.

Consider a typical modern automotive dashboard. The example shown above in Figure 1 relies on a 12.3-inch stretched LCD (liquid-crystal display) with 1440 x 540 pixel resolution. Given that drivers need to be kept informed of all the different parameters relating to a vehicle’s operation (including speed, RPM, tyre pressure, fuel level, oil pressure, navigation data), the display requires real time response, plus superior image quality.

Graphic controller devices currently available have difficulty in providing the required pixel clock necessary for certain standard or non-standard LCD panel formats. In our example, the 1440 x 540 resolution panel will require the pixel clock to be set around 50MHz in order to achieve the required 60Hz display refresh rate. Fast response is not just paramount in an automotive context though, it can be equally vital in medical equipment or industrial hardware...

Read the full article in EPDT's July 2021 digital issue... 

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