The inventions relate in general to the use of radio frequency identification (RFID) tags and RFID tag readers (also known as “interrogators”). In particular, the inventions relate to the configuration and operation of battery-powered RFID tag readers.
Portable RFID tag readers typically draw high current to provide output power required to read RFID tags at a distance. In battery powered devices, high current quickly depletes the system battery. Duty cycles are typically implemented such that the average current is within acceptable limit. As the duty cycle is reduced, there becomes a point at which reader aggressiveness is significantly reduced. Reader aggressiveness relates to how quickly and easily the reader can read a tag from the user's perspective. Aggressive readers do not appear to the user to be sluggish or incapable of reliable operation at the intended read distance.
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. RFID tags are classified based on standards defined by national and international standards bodies (e.g., EPCGlobal and ISO). Standard tag classes include Class 0, Class 1, and Class 1 Generation 2 (referred to herein as “Gen 2”). The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored wirelessly by an “RFID reader”, also known as a “reader-interrogator”, “interrogator”, or simply “reader.” Readers typically have one or more antennas for transmitting radio frequency signals to RFID tags and receiving responses from them. An RFID tag within range of a reader-transmitted signal responds with a signal including a unique identifier.
With the maturation of RFID technology, efficient communication between tags and readers has become a key enabler in supply chain management, especially in manufacturing, shipping, and retail industries, as well as in building security installations, healthcare facilities, libraries, airports, warehouses etc. However, current RFID tag reader designs result in battery life that is too short for many portable readers. A better arrangement is needed for managing power consumption of a portable reader so that it has longer battery life while still appearing responsive to the user.