Week 6-De-blackboxing of touchscreen

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Zijing Liu

Screen, one of the most common things we take for granted in the digital age, functions as a black-box, where users can only see its input and output. Whereas, after learning this class for several weeks, it is important for us to consider screen in a designer’s perspective ­– to de-productize and de-blackbox what is lying behind.

Before analyzing the affordance and constraints of the screen, I would like to clarify how screen works. There are two main types of screen, resistive and capacitive. The resistive screens are the basic ones that applied at ATMs and many other places. It senses our “touch” as pressure since when we touch resistive screen, we apply pressure on the screen. Then the underlying two electrically conductive layers connect, which helps to locate the position of the “touching point” and execute the order of that point. The other one is the capacitive screen, the most widely used on our smartphones, iPads and other electronic devices. This screen receives electrical charge emitted from our body that creates a “voltage drop” on the screen, then processes the order of that dropping position.

The first time I exposed to the word “affordance” and “constraints” was in “Universal Principles of Design”. After learning Murray’s concepts this week, I realize that everything has to be designed based on its affordance and constraints. The affordance of the screen is tightly connected with the socialization of human being. To design a screen, it cannot be too large or too small, too heavy or too light, which means it should be designed to be easily portable. The thinner, the better. Also, as a cognitive artifact, the screen is designed for people to read symbols and communicate with, that is the reason why screens are mostly rectangle instead of round. Moreover, it should be sensitive as well as accurate to the touch. For early screens, people had difficulties using the touchscreen because they had to push very hard to select icons. In fact, this constraint is still common in the current. For instance, the touchscreen of the package locker in my apartment is hard to use – each time I have to push very hard or using something sharper, like my nail, to force it to respond to my intention.

On the contrary, the constraints of touchscreen originate from its functions. The light of screen can be harmful to eyes, especially for those love to face screens in darkness – on bed before going to sleep. Besides, the touchscreen loses its function when wearing gloves or your hands are wet – it cut off the transmission of electrical charges. It annoys me when I have to pull off my gloves to touch the screen in cold winter or the water on my hand interfere with my operating.

Return back to the early point to think about affordances and constraints one more time, view everything from a perspective of designer, we will notice that everything has strong reasons to be designed in this particular way, even if it seems to be so ordinary.