The phalaenopsis, dendrobium, and the cattleya all require about the same light. They all need bright light in order to bloom, but not direct sunlight. The sunlight is too hot and would burn the leaves. I would suggest that you place them in a southern window, with a sheer curtain to protect them from the hot sun. Once the sun has passed over, you could pull back the sheer to allow more light to come in.
Light is important for the plant to grow and produce new leaves and roots.
It is also important for the blooming process. During the fall of the year, the days grow shorter. As this happens, it will trigger the blooming time. The plants will put on flower spikes, which is where the buds for flowers will be. When your plants begin to bloom, the blooms can last up to two months.