**1. Introduction**

Recent developments in image and video based technologies have enabled new services in the field of multimedia and recognition areas [1]. Those emerging services have been developed along with touchscreen based image processing and communication technologies. As a kind of emerging multimedia services, the necessity of underwater communication-device is increasing [2–4]. As industrial development of modern society and economic affluence have led to improvement in people's living standards, there are increasing demands for various marine leisure activities that will improve the quality of life.

Since underwater activities are not free and brain activity is reduced by breathing on air tanks, those limitations make it difficult to quickly respond to the surrounding risk factors (lack of air, dangerous marine life, and rapid algae). Therefore, a new type of dive computer is developing for marine leisure personnel to communicate underwater information [5–7].

In order to communicate clear and immediate information delivery through touchscreen based user friendly interface in the water, we implemented a new underwater communication-device that can be applicable to both professionals and publics for conducting marine leisure activities. The proposed underwater communication-device can support image/text data processing, and powerful visibility on the touchscreen. While conventional dive computers support several functionalities in terms of depth of water, water temperature, time, ascent/descent excessive speed alarm, and compass, the proposed communication-device, so called DiverPAD, can provide divers with touchscreen based memo functions (drawing and writing) as well as conventional functionalities.

The remainder of this paper is organized as follows: the previous works for recent dive computers are introduced in Section 2. The design and implementation of the proposed DiverPAD are described in Section 3. Finally, field test and conclusions are presented in Sections 4 and 5, respectively.

### **2. Previous Works**

Because scuba diving, as a kind of typical marine leisure activities, has a limitation by the breathing in the water, most divers have been using the dive computer to observe underwater information [8,9]. In addition, divers can obtain underwater information such as diver's location from tablet screen within a waterproof case [10]. As depicted in Figure 1, typical dive computers are manufactured to be worn on a human wrist and they provide a variety of underwater information about dive time, remaining air, water dive depth, and temperature. Since the information directly affects to people's lives in an emergency, the accuracy and reliability of the information obtained by the dive computer is important factor to the divers.

**Figure 1.** Statistical data in terms of marine safety accidents.

Even though conventional diver computers provide the basic information of underwater environment on display panel as shown in Figure 2, these cannot provide efficient communication methods among divers in the water. In addition, communication methods by using hand signals or writing board have limitations in transmitting and receiving accurate information in the water. In order to communicate underwater information about emergency situations in the water, new underwater device for supporting correct communication is needed to exchange accurate underwater information in the type of touchscreen based texts, symbols, and pictures [11].

In the case of conventional touch panels, when a point on the display screen is pressed or touched with a finger, a process to recognize the location corresponding to the pressed point works in three types, which are capacitive type, resistive film type, and infrared/ultrasonic type. Capacitive type is generally used in the conventional touch panels and it forms a constant capacitive layer on an insulating layer.

Because the weak electrical signal could not be properly detected in the water, when a finger touches a pad that is a transparent electrode on a substrate of the capacitive layer, touch signal is generated with its position. This is a difference between the existing touch panel method which detect the static signal and the proposed method to detect the weak electrical signal from the finger.

**Figure 2.** Functional items of conventional dive computers.

In this paper, DiverPAD was implemented with the capacitive method to enhance the correctness of electrical signal during marine leisure activities as shown in Figure 3.

**Figure 3.** Touch panel of DiverPAD.

The PVC (Poly vinyl chloride)/TPU (Thermo Plastic Polyurethane) of Figure 3 is a material that is less corrosive and resistant to chemicals and it has the characteristics of generating static electricity. Since it has the characteristics of plastic, it can protect the touch panel from sea water and it is possible to transfer the user's touch input to the LCD (Liquid Crystal Display)/OLED (Organic Light Emitting Diode) panel by inducing static electricity. Inside the PVC/TPU, an insulating material, so called glucerine, was filled to allow smooth touch input.
