Stating a specific class of computing device, such as touchscreen devices, in the first independent claim

Question

Is there necessarily any risk or self-imposed limitation in having a Claim 1 statement like this –

A method for [fill in details here] on a computing device controlled by touchscreen input, and ...

– if there will also be a dependent claim that covers other means of controlling the computing device, such as by a moving cursor?

The tentative reasoning is:

1. The invention actually is primarily for touchscreen devices, but would also be applicable in other environments;
2. Based on prior art cited in an earlier rejection, it seems I may have to narrow it in this way, but I am not sure.

Answer 1

Is it essential that the computing device has a touchscreen? If not, then it should not be in your independent claim. It is generally irrelevant whether it is your most likely implementation or not, if your goal is to maximise your scope of protection.

That is, by including this feature, you are limiting your protection to a single embodiment. While this can be necessary if there is prior art, you do not seem to be specifically aware of any prior art requiring this. Because of this, it seems an own goal to limit yourself unnecessarily.

Moreover, you cannot have a dependent claim broaden an independent claim, as that is not the role for a dependent claim. Your dependent claim would likely be objected to.

Answer 2

As Macas answer already says, you can't have dependent claims that protect anything outside the scope of the independent claim.

What you can do would be saying “... controlled by an input device, preferably a touch screen,“. This gives you a way of having a dependent claim (touchscreen) in the independent claim as an optional element. So basically two claims in one.

Note however, if you need to add the touchscreen the other claims with other input means won't be dependent anymore and you'll likely have to give them up.

More important however, using a touchscreen as an input device will, in almost all cases, not be enough to merit non-obviousness. So apart from novelty against unpublished applications in the EU for example, where unpublished prior art doesn't count for inventive step, there is likely no benefit from adding the touchscreen as a must-have feature.

The person skilled in the art knows that touch screens are a thing today. If your invention works without one, it's not inventive to add one (>99% of the cases).