1.1 Introduction
This research work design and implementation of automatic hand-dryer with temperature display is achieved in several blocks all combined to form one functional unit. The first block in the opto-coupler realized with laser diode and LDR whose output is conditioned by 74LS132 that generates control logic. This control logic is used to bias a transistor switch that energizes the electromagnetic relay which switches the dryer. The control logic is also used to trigger/power the temperature display circuit. This section is realized with IC linear temperature sensor (LM35) whose output is fed to a quad-comparator with Hysteresis. This comparator output reset a frequency generator which is counted by a 2-digit decimal counting unit that displays the temperature of the blowers air in degree calcius. The system dries the hand and displays the temperature using seven segment display.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
The basic function of a hand dryer is to dry hands using an electric source. Hand hygiene is a very important aspect in preventing spread of communicable diseases. Since many disease-caused by germs spread through touch, hand dryers were devised so that people can dry their hands without actually touching the roll of towel available for common use in public restrooms. Hand drying machines not only help in maintaining hygiene, but also help in reducing waste produced by the use of towels.
Some years back, these devices were switched on using a button. When the button was pressed, the device started blowing warm air for drying hands. But nowadays hand dryers have infrared motion sensors installed in them. The device detects motion and automatically turns on when hands are placed for drying. Similarly, it automatically turns off when hands are moved away from the dryer, thereby preventing wastage of electricity.
Warm air is produced by a hand dryer using a heating coil made up of Nichrome, a hybrid of chromium and nickel. The warm air is then blown out of the device through a tube or a vent facing downwards. Hands are placed in the path of warm air coming out of hand dryer for drying. The warmth and pressure of air coming out of the dryer is sufficient to evaporate water from wet hands. First, the air pressure blows off water droplets from the hands and then the warmth dries out the moisture from the hands. Traditional hand dryers need around 45 seconds to dry hands, whereas new-age dryers take around 15 seconds to do this task.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to design and construct an Automatic Hand Dryer with Temperature Display.
1.3 Statement of Problems
The transmission of bacteria and other micro-organisms is most likely to occur from wet skin than from dry skin. Careful hand drying is a critical factor determining the level of touch-contact associated bacterial transfer following hand washing. Hence, the proper drying of hands should be an integral component of effective hand hygiene procedures in health care settings.
Cloth towel, paper towel and electric air hand dryer are commonly used to dry washed hands. Although there is wide consensus that hand drying is an essential part of hand hygiene process, there is much less consensus regarding the most effective method of hand drying in terms of hand hygiene in health care settings.
1.4 Aim and Objectives of Study
The aim of the study is to design and construct an Automatic Hand Dryer with Temperature Display. In achieving this aim, the following specific objectives were laid out as follows:
- To construct a machine that will automatically dries up the wetness of a hand, when those hand are placed before it.
- To design an hand dryer that will showcase the current temperature in use.
1.5 Significance of Study
Hand dryers have been popular and more economical in many homes, hand dryers can cut cost by 99.5% (for example a company may spend 500,000 per year on paper towels, where as the hand dryer expenditure would be as low as 30,000 per year. This would vary due to cost of towels .Also, due to the reduction in liter and waste in comparison with towels, which cannot be recycled, hand dryers are also claimed to be better for the environment.
Hand dryers are more hygienic compared to a towel. It does not require close contact before it commences its operation neither does it require washing after use.
This study will be of immense benefit to Engineers and other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on Design and Construction of an Automatic Hand Dryer with Temperature Display. The automatic hand drier is operated automatically using a sensor called light dependent resistor (LDR).
The LDR operates whenever it senses darkness or shadow in the absence of light. The resistance of the LDR is reduced whenever it experiences darkness thereby allowing the flow of electric current through it. Thus, this project is limited to a light dependent resistor; there are other types of sensor used in the modification of an automatic hand drier.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
