Active pen

An active pen (also referred to as active stylus) is an input device that includes electronic components and allows users to write directly onto the LCD screen surface of a computing device such as a smartphone, tablet computer or Ultrabook. The active pen marketplace has long been dominated by N-trig and Wacom, but newer firms Atmel and Synaptics also offer active pen designs.

Active Pen are commonly used for electronic notes, drawings, document annotations, and accurate object selection. When used with OCR (Optical Character Recognition) software, the stylus input of the stylus can be directly converted to digital text and stored for direct editing.

An active pen is generally larger and has more features than a stylus. Digital pens typically contain internal electronics and have features such as touch sensitivity, input buttons, memory, writing data transmission capabilities, and electronic erasers.

Technology
Active Pen have a directional electromagnetic field. Conductor loops in the display of the device to be operated determine the pointer position by comparing the induced signal strengths. Additional pen information such as pen printing or pressing a key on the pen are digitized, modulated on the electromagnetic field and determined together with the position data on the computer of the device to be operated. The pins are powered either by a built-in pen in the pen or directly from the device to be operated by induction.

The input signals are recorded in the terminal and the movement of the stylus is graphically reproduced. The pen can be equipped with keys and thereby be used as a replacement for a conventional pointing device. Most devices that can be operated via an inductive input method for use with an active stylus have a second capacitive input method for finger operation.

Active pens
Active pens, such as N-trig’s DuoSense Pen™, include electronic components whose signals are picked up by a mobile device’s built-in digitizer and transmitted to its controller, providing data on pen location, pressure, button presses and other functionality.

Active pens are typically used for note taking, on-screen drawing/painting and electronic document annotation, as well as accurate object selection and scrolling. When used in conjunction with handwriting recognition software, the active pen’s handwritten input can be converted to digital text, stored in a digital document, and edited in a text or drawing application.

Positional pens
Position-based digital pens use a facility to detect the location of the tip during writing. Some models can be found on graphics tablets made popular by Wacom, and on tablet computers using Wacom’s Penabled™ technology.

Capacitive pens (multitouch compatible)
Capacitive pens multitouch compatible, generate a signal used by multitouch screen to detect the location of the tip during its movement while writing or drawing. They are compatible with most smartphones and tablets with capacitive-multitouch screen as iPhone, iPad, Samsung, LG, etc.

Functions:
Erase – erase the input directly, for example, by using a button or the back of the pen
Handball Identification (Palm Rejection) – In the posture position, the capillary screen is temporarily disabled due to an approach of the stylus to a few centimeters on the display, thus preventing unwanted input from the palm or fingers.
Pressure sensor – In the pen, the contact pressure can be detected and transmitted to create a realistic font representation (see Fig. 3 – Pressure sensitive representation)
Hovering – If pens are held without direct contact via displays, the hover or mouse-over effect can be imitated.

Positional pens:
The electronic components generate wireless signals that are picked up by a proprietary digitizer and transmitted to its dedicated controller, providing data on pen location, pressure and other functionalities. Additional features enabled by the active pen’s electronics include palm rejection to prevent unintended touch inputs, and hover, which allows the computer to track the pen’s location when it is held near, but not touching the screen. Most active pens feature one or more function buttons (e.g. eraser and right-click) that can be used in the place of a mouse or keyboard.

Capacitive pens:
There is a new technological generation of active capacitive devices compatible with multitouch screens that allow seeing the tip while drawing a fine line on the screen, giving an accuracy impossible to achieve with a finger, as this covers the point of contact when drawing or writing. (multitouch capacitive technology is originally designed to be activated by fingers),

Active vs. passive pen: The main difference between an active pen and the input device known as a passive stylus is that the last can also be used to write directly onto the screen, but it does not include electronics and thus lacks all of the features that are unique for an active pen: touch sensitivity, input buttons,etc… Active pen devices support most modern operating systems, including Google’s Android and Microsoft Windows.

Active vs. passive capacitive pens
Some typical passive stylus include a large tip made of rubber or conductive foam in order to emulate a user’s finger, rather than the more accurate ballpoint pen-like tip used in the active pen.