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Lighting : April 2010 Whos Who of Lighting
40 LIGHTING MAGAZINE | April/May 2010 TECHNICAL FEATURE Therefore, test subjects were recruited from universities in two different socio-economic backgrounds and geographical locations for this pilot study, to evaluate interactivity and usability of existing lighting control interfaces. Apart from being the author’s home and host countries respectively, India and New Zealand were the preferred locations as they provided the two different socioeconomic backgrounds required for this study. Subjects were chosen randomly from the School of Architecture and Planning, Anna University of Chennai in India and the School of Architecture and Design, Victoria University of Wellington in New Zealand. As statisticians have found that it takes a sample size of about thirty to fulfil an assumption, the number of test subjects from each university was arrived at thirty (Salkind 2007). equipment for the survey The survey involved experiments with manual controls for luminous intensity and scene selection. For the experiment on manual control of brightness three different types of dimmers were used for controlling the brightness: pushbutton, rotary dial and slider. The Rania model from Lutron with a dual increase and decrease function was used as the push-button type dimmer. The digital dimmer memorises the last luminous intensity level and includes green LEDs to indicate the intensity level. A rotary style regulator for fans by Anchor was used as a rotary dimmer. The regulator has an in-built switch to turn on/off lights along with dimming function with the rotation of the dial. The Lyneo model from Lutron with an adjustable round slider to increase and decrease luminous intensity of lamps was used as the slide dimmer for this experiment. The position of slider indicates luminous intensity level at a glance with a contoured pushbutton to turn the light on/off. However, the subjects were not told about any of these additional functions that the dimmers can perform besides controlling luminous intensity. The lamps used for the experiment were 40W incandescent A-type lamps from Philips. The experiment for scene selection involved five different types of screen-based interfaces with a projection of four different scenes for preset control to recall scenes. The four lighting scenes in a conference room as downloaded from the Lutron lighting controls website were: ‘Night Light’ scene for a low-level general lighting when the room is unoccupied; ‘Maintenance’ scene when all the lights in the room are switched on for maintenance and cleaning; ‘General Meeting’ scene when lighting is focussed on the conference table; and ‘A/V Presentation’ scene when selective low-level lighting is maintained for taking notes during an audio- visual presentation. The five different types of interfaces used for scene selection have control function representations that have the following characteristics: numerical [1, 2, etc.]; textual [Night Light, Maintenance, etc.]; labelled scenes [Scene 1, Scene 2, etc.]; graphical images of the scenes; and a combination of text and graphical images of the scenes. These scenes were set-up on an Apple Macintosh notebook computer screen. Subjects had the choice of selecting different scenes with a split screen of the five different interfaces and the four scenes. survey results Although a full-fledged statistical analysis is underway, preliminary analyses show interesting results. In terms of interactivity i.e. appearance, grabbability and touch response, subjects preferred the rotary or the sliding dimmer over the push-button dimmers. Although for some subjects the slider knob seemed too small to grab in their hands, and larger knobs were suggested. In terms of usability i.e. ease of use, subjects found the rotary dimmer very user-friendly. The pushbutton switch for turning on lights for the sliding and pushbutton dimmer was annoying for some subjects. Subjects found the sliding dimmer a trifle too tight FIGURE 1. Pushbutton, rotary and sliding dimmers FIGURE 2. Scene selection interfaces ➤ FOR THE EXPERIMENT ON MANUAL CONTROL OF BRIGHTNESS THREE DIFFERENT TYPES OF DIMMERS WERE USED FOR CONTROLLING THE BRIGHTNESS: PUSHBUTTON, ROTARY DIAL AND SLIDER.
Whos Who of Lighting 2009
April May 2011