Nu Tech and DVDInfoPro Bring You DC Erase

Press Release: In an industry first for consumer level DVD writers, Nu Tech are utilising the capabilities of the Nexperia PNX7850 chipset to bring us DC Erase technology. This is made possible via six months of work between the Nu Tech engineers and the creator of DVDInfoPro, Nic Wilson.

Just what is ‘DC Erase’ technology?
The term DC Erase means ‘Direct Current’ Erase. It is also known as a ‘Physical Erase.’ The idea is actually an old one, not yet seen in consumer optical hardware such as DVD writers. All previous recording marks or signs of recording are erased. It is important to note this function does not replace the normal erase, blank and format functions. DC Erase works by using a continuous laser power, to revert the layer to a highly reflective state. This can overcome some problems where written data could disturb the OPC. This function may lead to the maximum number of DOW cycles to be reduced. DVDInfoPro therefore recommends this function is used on those RW discs that have become problematic. A Quick function is also offered for those RW discs where the problem may only exist in the beginning of the disc.

Rewriteable technologies:
It is important to understand how rewriteable technologies work, so that we can better understand how DC Erase works in comparison to it. The technology behind DVD-RW is optical phase-change, which in its own right is nothing radical. However, the technology used in DVD-Rewritable does not incorporate any magnetic field like the phase-change technology used with magneto optical technology. The media themselves are generally distinguishable from DVD-R discs by their metallic grey colour and have the same basic structure as a DVD-R disc but with significant detail differences. An RW disc's phase-change medium consists of a polycarbonate substrate, moulded with a spiral groove for servo guidance, absolute time information and other data, on to which a stack (usually five layers) is deposited. The recording layer is sandwiched between dielectric layers that draw excess heat from the phase-change layer during the writing process. In place of the DVD-R disc's dye-based recording layer, DVD-RW commonly uses a crystalline compound made up of a mix of silver, indium, antimony and tellurium. This rather exotic mix has a very special property: when it's heated to one temperature and cooled it becomes crystalline, but if it's heated to a higher temperature, when it cools down again it becomes amorphous. The crystalline areas allow the metallic layer to reflect the laser better while the non-crystalline portion absorbs the laser beam, so it is not reflected.

Traditionally, a DC erase was used to erase or clear data completely from recorded magnetic media by sending a direct current via write heads on metallic and magnetic tape mechanisms. It can be thought of as a complete degaussing of your media, even though it is not a magnetic process perse. Hard disc drives work on the same principle. A diagram has been provided to show what DC erase does in relation to recordable media and how the different signal routines affect the output media.


Difference in write procedures explained as routines

But what does this mean for the consumer?
The simple answer is that it allows previously used CD-RW and DVD-RW/+RW to be returned to their ‘factory’ pressed state. Have you ever noticed that after one use, your CD-RW/DVD-RW/+RW will never have the same colouration again? DC Erase changes this. It in effect returns the media to pristine condition, provided no physical damage is done to the substrate layers of the media. Many of the problems associated with too many writes to an RW medium can be fixed using DC Erase.

A simple test of validity:
A test was carried out using RICOHJPNW11 4X +RW DVD media. This test was carried out using the Nu Tech DDW-082 provided using the B377 firmware. The testing environment is as follows in table 1.0 (below).

The DC Erase was carried out using Nic Wilson’s DVDInfoPro v3.25. Regulated power supplies and climate controlled hardware were implemented. The images we have provided were scanned on a flatbed cannon scanner at 600-1200dpi momentarily after the write/erasure process. We show the three discs, i, ii, and iii – after each step. (Figure 2.0, below):

i. Disc 1. We take a brand new, blank DVD+RW:
ii.Disc 2. We then write a full data set to it (notice the colouration)
iii.Disc 3. Finally, to bring it back to its factory fabricated state, we use the DVDInfoPro DC Erase command, coupled with a Nu Tech DDW-082: (Notice the change in colouration, back to factory state)

Discs 1, 2, and 3 respectively, in each phase of the process:


Disc 1 – Factory State RICOHJPNW11


Disc 2 – Full ISO write in Nero 6.3.1.25


After full DC Erase with DVDInfoPro v3.25

Further to this, we can see from testing – even with the naked eye, let alone a high resolution scanner, an obvious difference in the underside of the media after a DC Erase has taken place:


Comparison overlap of three stages of the same media

How can I use DC Erase with my current writer in conjunction with DVDInfoPro?
The new version of DVDInfoPro will have this feature included. It can be clearly be seen highlighted below along the standard DVDInfoPro toolbar. Look for it in your next download!


DVDInfoPro v3.24, with DC Erase technology enabled on all new Nu Tech DVD writers.

Compatibility with your hardware:
Any Nu DDW based drives, SDW, both internal and external models and OEM units such as the Philips SDVD-8431 are supported. If you are unsure of your compatibility, you should contact your drive vendor/manufacturer.

Conclusions:
After reviewing the functions and finding a suitably aged, presumably damaged DVD+RW, we decided to see if using the DC Erase function would actually allow the media to be written to with any form of integrity again. After writing to the disc in its standard “used” state, we received CIRC errors on read back. After using DC Erase on the same disc, then writing the same ISO back to the media, we have a functioning image, without and CIRC errors present. This is a basic testimonial to the fact that a DC erase does indeed afford us new usage out of presumably damaged or ill-functioning media. Comparative tests for RPM and read back analysis will follow in the coming weeks.

Thanks to Zebra for this article,