On the 8th December 2015 the discussions on creating the ZX Spectrum Next were in their infancy. Henrique Olifiers had approached Rick Dickinson only a few days earlier to ask if he would be interested in taking on the role of industrial designer for the project. On the subject of the keyboard, Rick had this to say.
Using existing Sinclair membranes as a reference, and factoring in specific requirements based on the current case design, a prototype membrane was created. This was non-functional and was designed to address a number of key points.
- The tracking is on the correct sides in relation to the connectors
- That they fit into the connectors and the contact pitch is correct
- The flextail lengths are suitable when assembled into a prototype unit
- The reenforced areas at the tail termination are long enough to insert into the connectors and short enough to bend through 90 degrees without clashing with the upper case
- The position of clearance holes for features such as bosses and heat swage pins is correct
The results from the membrane testing showed that the pressure required to activate the triple contacts was too high.
- T0 is typically not seen by the customer and is the very first set of injections
- T1 will incorporate corrections to the mould typically based on internal feedback. The results will be assessed by the customer.
- T2 Any subsequent corrections required based on T1 feedback
- Active force for the membrane without scissor and keycap >200g force
- Active force for the membrane with scissor and keycap >200g force
More suggestions come in with regards to increasing the dome size but there are restrictions in how large they can go because of the scissor mechanism.
Simple functional testing begins on the prototype complex membrane and so far so good.
- The new keyboard membrane is workable which is great news. As this is a new special structure compared with the usual keyboard membranes, the engineers start the process of making one more test membrane, using exactly the same method but in the layout of a PC keyboard. Once this new membrane is installed, then actual keypress testing can begin.
- The process of checking all the required printing on each keycap is kicked off and the results will be known soon.
- Flex tail reinforced section change to be implemented in the next prototype as per observations.
- The new keyboard membrane sample which is functional is shipped over from China to the UK, this membrane can be fitted to a Next board to run additional tests.