HTC and Sharp have unveiled devices featuring next-generation screens.
HTC's J Butterfly phone has a 5in (12.7cm) display offering an industry-leading 440 pixels per inch.
This offers 25-40% higher resolution - meaning more detail - than comparable devices from Samsung, Apple, Nokia and LG.
Sharp's new Aquos Pad tablet is the first to use its new Igzo technology which promises sharper images while using less power.
Sharp has previously said at least one of its customers also planned to incorporate the innovation in its devices.
Several device makers have signalled plans to announce new tablets over the coming weeks.
HTC's Android-based device is set to go on sale in Japan in December.
Its size places it somewhere between a typical smartphone and tablet in a category some term a "phablet".
The Taiwanese firm is marketing both the size and resolution of its screen as being ideal to watch 1080p movies.
Smaller, densely packed pixels mean users can hold a device to their face without being able to distinguish the individual blocks of colour used to make up an image.
HTC's 440ppi - pixels per inch - resolution offers a performance-boost over rival flagship devices including Samsung's similarly-sized Galaxy Note 2 with a 267ppi screen.
Apple's iPhone 5 offers 326ppi, Nokia's upcoming Lumia 920 332ppi and LG's Optimus G 318ppi.
To support the facility, HTC has included Qualcomm's top-end Snapdragon S4 Pro processor.
However, it has not yet disclosed what toll supporting the feature will have on its battery.
Sharp's new tablet takes a more radical approach by being the first device if its kind to incorporate a new kind of LCD (liquid crystal display) technology.
Igzo (indium gallium zinc oxide) screens have higher translucency than standard TFT (thin film transistor) LCDs, meaning they are better at letting light pass through them.
As a result devices that use them need fewer LEDs (light-emitting diodes) to provide backlighting, allowing the screen to take up less room and use less power.
Sharp boasts its new Aquos Pad SHT 21 tablet can last two and a half times longer than its predecessor.
The company also suggests it has better touch accuracy than rivals, making it easier to write notes with a stylus.
The product has a 7in screen, but Sharp has said that it would also make panels in 10in and 32in varieties, suggesting its use in other tablets and desktop computers.
The firm said its new tablet would launch in Japan in December, but has not released details of plans elsewhere.
The announcements come ahead of a flurry of new releases.
Over the next fortnight Microsoft, Apple and Google have all scheduled major product launches.
Several Windows 8 tablets - including Microsoft's own Surface - have already been unveiled and will go on sale next week. There is also the expectation of an "iPad Mini" and new Nexus-branded devices.
One analyst said that with so many competing products on offer, display quality was become a deciding factor for some consumers.
"Screen resolution has become a differential point for many manufacturers," Chris Green, principal technology analyst at Davies Murphy Group Europe, told the BBC.
"Given that many people now use their devices to stream video, having a high-resolution that can best show off HD video is far more important than it was two years ago.
"There is still a trade-off though as some of these displays consume more power as a result, and battery technologies have not kept pace with other advances. Since screens are the biggest power drain on mobile devices, that's why a lot of research is going into how to reduce their energy needs."