Why the Bistable display is a popular option for custom LCDs
The Bistable display has been introduced to the public thank to E-book readers such as the Amazon Kindle®. This is a new type of custom LCD. This article on the Bistable LCDs, or zero power LCD, gives a quick Q&A on this new display technology. To read the first of this series, click on part one.
The concept of a display module that can hold an image without any drain to a battery has become popular as more OEM manufactures seek to incorporate this technology in their next generation of products. In a perfect world, automobiles would require no fuel; air conditioners would run without power and food crops would require zero water. Although we do not live in a perfect world, there are new types of custom LCDs that can display an image and requires zero power.
This is great news if you manufacture a battery powered product since the LCD Displays is one of the greatest power draining devices in your bill of materials (BOM).
So understandably, the idea of converting your largest power drain to a component that no longer requires power is tempting.
For this reason, we receive many calls from OEM manufactures that want to switch to a Bi-stable LCD Module in their next generation product. But as good as this technology sounds; it is not the ‘perpetual motion’ of custom LCDs. There are some restrictions, including both technology and cost that make this display the not-so-perfect solution for every application.
Note: It is important for the reader to understand that this display technology, like any technology, will change and some of the information in this paper will be obsolete in a short time --- No, it will be obsolete in a very short time.---
This article was written to provide a quick overview of advantages, disadvantages and costs associated with incorporating a bistable LCD display in your next custom LCDs application.
Bi-stable LCD Technology: where-to and where-not-to use it:
Bi-stable LCD Technology also referred to as Cholesteric displays, are able to hold an image without any power drain, but they do require voltage to switch the image.
So if your product is a price tag for bananas at the grocery store, and the image will be the same for the next three weeks; this is a great application. If, on the other hand, you are using this in a clock with a display that changes every second, you will quickly drain the battery and lose any power saving advantage you may have realized.
Bistable Display Modules: Questions and Answers
We address several common questions about this new power saving technology that is battery friendly.
Q1: What is the largest size glass available for a bistable display?
A1: The largest size possible bistable glass is 100mm x150mm or 4” x 6”.
Q2: What is the most common type of chip configuration used on a Cholesteric LCD?
A2: At this time Chip on Board (COB), Chip on Glass (COG) and Tape Automated Bonding (TAB) are available. When designing a custom bistable LCD display with a resolution of 128x64 or lower, we recommend COG. For resolutions above 128x64 it is suggested to consider TAB or COB.
Q3: What is the highest resolution graphics that a custom bi-stable module can display?
A3: 800*600dots, it is possible to build higher resolution, but not recommend at this time.
Q4: Can a bistable display use a backlight?
A4: Bistable displays are reflective which is one reason why they are excellent in direct sun light. It is possible to install a side lit LED with a reflective polarizer.
Q5: What is an estimated tooling cost to design and build a bi-stable LCD panel?
A5: At the time of this writing, the tooling fees (NREs) start around $7,000. The tooling fees include design support, schematics and samples.
Q6: Does the bistable display require a charge pump, DC/DC converter or booster circuit?
A6: Yes, this makes it a poor choice for intrinsic/explosive environments.
Q7: What type of bus interfaces do you support?
A7: Serial Peripheral Interface (SPI) is the most popular, but IC2 can be selected, but at a higher cost.
Q8: What is the operating temperature range for a Bistable display?
A8: Operating Temperature: -10 ~ +60 ℃, although it is possible to operate the display at a lower temperature with the addition of a heater.
Storage Temperature: -20 ~ +70 ℃??
Q9: What is the standard lead time for the custom bistable display?
A9: Sample Lead time: As little as three to four weeks, depending on availability of material.
Production Lead time: An estimated twelve to fourteen weeks.
Q10: What are your Minimum Order Quantities (MOQ’s) for a custom bistable display?
A10: MOQ’s start as low as 1,000 displays.
Design your custom bi-stable display TODAY. Contact one of our sales engineers.