In this paper, a haptic rendering system for a virtual control panel using an encountered-type haptic device is presented. The system can render different switches on a panel in virtual space by a single haptic device. A motion planning algorithm of the encountered-type haptic device is proposed in order that the device is properly encountered by the user's finger at the switch locations while it avoiding unintended collisions against the user elsewhere. Two improvements are made to the previously proposed motion planning algorithm. The one is refinement on the weighting function in the algorithm to reduce the duty of the device motion. The other is introducing virtual surface coordinates to the motion planning so that unintended collisions of the device against the user are completely avoided in free space. The proposed method is verified by numerical simulation.