Input Devices

July 18, 2010

in Hardware Review

Defined as devices used for inputting information into a computer, input devices can be specifically chosen to suit the needs of the population and customize the studio environment. Whether a need exists for a trackball, joystick, graphic tablet, digital camera, or scanner, today’s continuously developing technology makes these devices and others accessible and affordable for the average computer user.


Referring to the input devices that move the pointer (cursor) on the computer screen, the most widely used pointing device is the mouse. The standard mechanical mouse houses a single ball in its body that is able to rotate in any direction. The ball’s motion is then detected using perpendicular wheels. An optical mouse detects movement using an optical sensor on its underside, paired with a light-emitting diode to illuminate the surface. Using a sensor to take successive pictures of the surface the mouse is operating on, the changes between one image and the next are processed and translated into movement. Personally, the major drawback to using a mechanical mouse instead of an optical mouse is that it requires occasional cleaning. When a mechanical mouse does not seem to work properly and causes the cursor to jump erratically around the screen, the motion-detecting wheels inside the mouse body needs cleaning. From my work as a computer lab assistant, I can say from experience that the task of scraping away the black crust that forms from the accumulation of dust and dead skin cells is quite unpleasant.

As far as whether a mouse should have one button or more than one is primarily a personal choice. Apple has always shipped computers with a single-button mouse, whereas most other platforms use a multi-button mouse. Apple claims that single-button mice are more efficient, and that multi-button mice are confusing for novice users. Conversely, with a single-button mouse, even simple operations like “cut and paste” become awkward. Mice usually packaged with most computer systems but can be purchased separately for $5 to $170.


Like an upside-down mouse, trackballs consist of a ball housed in a socket containing sensors to detect the rotation of the ball. Common on CAD (computer aided design) workstations for ease of use and on portable computers where there may be no desk space, some trackballs clip onto the side of the keyboard and have buttons like the standard mouse. Most people move the ball with their hands, but it can also be operated with a chin, elbow, foot, or stick held in the mouth. Because trackballs come in many sizes, people with limited fine motor ability may find it useful to choose a trackball with a larger ball. These devices are available at computer stores for $20-$130.

Touchpad & Pointing Stick

While the major pointing device for desktop computers is the mouse, for laptop computers it is the touchpad and pointing stick. Touchpads vary in size but are rarely made larger than 50 cm². They operate by sensing the capacitance, or electrical charges, of a finger such that the motion of the user’s fingers causes motion of the cursor. Pointing sticks, on the other hand, looks like a pencil eraser and sits between the G, H and B keys of the laptop keyboard. The pointing stick is moved with the forefinger and operates by sensing the applied force. These two devices come standard on today’s laptop computers and do not need to be purchased.

Touch Screen

One method of bring the touch technology to desktop computers is through touch screens. Touch screens use a clear glass panel overlaid onto the display and separated by spacers. When the panel is pressed, the coordinates pick up the location of the touch on the screen. Since the person points directly to what he/she wants, it is cognitively easier to use. Monitors with this feature built in cost about $400 to $830 while add-on-kits are available for desktop and laptop screens from $170 to $290.

Graphic Tablet

Sharing the pressure-sensitivity technology of touch screens are graphic or digitizing tablets. These devices typically consist of a large, flat, pressure-sensitive surface and a pen-like stylus for drawing on the surface. Some tablets also come with a cordless mouse and penholder. One of the benefits of the graphic tablet is that it offers a more ergonomic method of input that reduces the likelihood of developing repetitive strain injury or carpel tunnel syndrome. Another advantage of a graphics tablet is that it is easier to vary the width or density of a drawn lines on the screen. Because of the responsive pressure-sensitivity, natural looking freehand graphics are possible. “Most tablets have either 256, 512, or 1024 pressure levels…. The higher the pressure-sensitivity the more responsive and natural your tablet will feel and the more control you will have” (Chastain, n.d., ¶6). Today Wacom and Aiptek are the leading manufacturers of graphic tablets and charge $100 to $750 depending on the size of the tablet surface, which can range from 4” x 5” to 12” x 18.”


Joysticks employ a vertical handheld stick mounted on a base that pivots. For some, a joystick may be easier to grab than a mouse and because it requires a smaller range of motion than a mouse it can also be operated by chin or mouth movements. These devices are typically used to control computer or video games but can also be functional in other applications. Joysticks range in price from $18 to $60, depending on its features.

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