A disclosed a gaming machine includes an input mechanism with a non-physical contact data interface. The non-physical contact data interface may be capable of reading loyalty program data from a loyalty program instrument without contact between the loyalty program instrument and the non-physical contact data interface. The input mechanism with the non-physical contact data interface may be one of a bill validator, a bar-code reader and a Radio Frequency Identification (RFID) tag reader. The loyalty program instrument may be a substrate including at least one of a 1-D bar-code printed on the substrate, a 2-D bar-code printed on the substrate, a symbol printed on the substrate, alpha-numeric character printed on the substrate, a RFID tag embedded in the substrate, a RFID tag printed on the substrate and combinations thereof. The loyalty program instrument may be used to store an index to a record in a database or a portable data file.

Flexible loyalty points programs

A method and apparatus for tracking items automatically is described. A passive RFID (Radio Frequency IDentification) tag is used with a material tracking system capable of real-time pinpoint location and identification of thousands of items in production and storage areas. Passive RFID tags are attached to the item to be tracked, remote sensing antennas are placed at each remote location to be monitored, interrogators with several antenna inputs are connected to the sensing antennas to multiplex the antenna signals, and a host computer communicates with the interrogators to determine item locations to an exacting measure.

RFID material tracking method and apparatus

Wireless measurement systems with passive surface acoustic wave (SAW) sensors offer new and exciting perspectives for remote monitoring and control of moving parts, even in harsh environments. This review paper gives a comprehensive survey of the present state of the measurement systems and should help a designer to find the parameters required to achieve a specified accuracy or uncertainty of measurement. Delay lines and resonators have been used, and two principles have been employed: SAW one-port devices that are directly affected by the measurand and SAW two-port devices that are electrically loaded by a conventional sensor and, therefore, indirectly affected by the measurand. For radio frequency (RF) interrogation, time domain sampling (TDS) and frequency domain sampling (FDS) have been investigated theoretically and experimentally; the methods of measurement are described. For an evaluation of the effects caused by the radio interrogation, we discuss the errors caused by noise, interference, bandwidth, manufacturing, and hardware tuning. The system parameters, distance range, and measurement uncertainty are given numerically for actual applications. Combinations of SAW sensors and special signal processing techniques to enhance accuracy, dynamic range, read out distance, and measurement repetition rate (measurement bandwidth) are presented. In conclusion, an overview of SAW sensor applications is given.

A review of wireless SAW sensors

A brief overview of acoustic wave sensor physics, materials, sensor types, and applications is presented in this paper. Emphasis is placed on the different types of acoustic wave sensors, their respective advantages, and their specific applications in industry.

Acoustic wave technology sensors

A review of sensors based on piezoelectric crystal resonators is presented. The survey focuses on the fundamental resonator modes rather than on the variety of surrounding support configurations in special sensor applications. First, the general properties of vibrating crystal sensors and their inherent superiority are described. The sensor concepts utilizing either homogeneous resonators with temperature and pressure (stress) as primary measurants or composite resonators with areal mass density and viscoelastic properties of the 'foreign' layer as primary measurands are discriminated. A comparison between bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators with respect to their primary sensitivity functions and principal capabilities for sensor applications is given and the importance of recent investigations on Lamb wave and horizontal polarized shear wave (HPLW) interdigital transducer (IDT) resonators is acknowledged. The importance of mode purity for high dynamic range sensors based on resonators and some aspects of the demand on specialized electronics are emphasized. The present state of established sensors based on primary sensitivities, e.g., quartz-crystal thermometers, pressure transducers, thin-film thickness and deposition-rate monitors, viscoelastic layer analysers (crystal/liquid composite resonators) is reviewed. A selection of the most promising recently investigated vibrating crystal sensors utilizing indirect sensitivities is described, including the wide field of analyte-selective coatings and resonator-based immunosensors or immunoassays. Finally, the potential of alternative piezoelectric materials for future sensor developments is briefly discussed.

Sensors based on piezoelectric resonators

A passive surface wave sensor for obtaining measurement values in which the measurement value is transmitted by radio from the remote point of measurement to an interrogation device (1) which transmits energy by radio to the sensor component (5, 15) as an interrogation pulse. The surface wave sensor of the invention is suitable for contactless measurement value collection. In this sensor a surface wave arrangement is the sensor component and there is a surface wave reference component for phase discrimination and/or propagation time measurement. As a further embodiment there is a sensor operated by chirped transmission signals with chirped reflectors in which there is a reference function in the arrangement replacing the reference component. An embodiment of the sensor with a chirp function has the property of an immanent temperature-compensated sensor (Fig. 12, 13) for measuring physical or similar quantities elsewhere.

Passive surface wave sensor which can be wirelessly interrogated

A survey is given of SAW sensor systems. Three categories of sensors are defined as transit-time, resonator and chirp-type devices and each category is subdivided into active and passive signal-processing systems. In these, the mechanical change of the SAW device is evaluated by difference measurements of the transit time, phase or resonance frequency, which are described quantitatively. To show the high resolution of active sensor systems, an electronic spirit level (based on SAW resonators) is described. New SAW chirp sensors allow the dispersive interdigital transducer or reflector geometry to be adjusted to the sensor system resolution and measurement range. In passive systems the sensor device is connected to an antenna. The SAW is excited by an interrogating radio impulse. After a SAW transit time, the sensor radiates back to the interrogator an impulse containing the sensor's information. The time and frequency response of all sensor categories and the possibilities of temperature compensation are discussed.

Mechanical sensors based on surface acoustic waves

Surface acoustic wave (SAW) radio sensors make it possible to read measurement values from a remote location. The decisive advantage of these SAW sensors lies in their passive operation with no need for a separate power supply, and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW sensors are maintenance free. The physical or chemical properties that shall be detected change the propagation characteristics of the SAW. In this paper we compare the sensitivity of different types of SAW sensors. These are resonators, reflective delay lines, and dispersive structures. Examples for several applications are presented.

SAW devices as wireless passive sensors

In our paper we present the application of surface acoustic wave (SAW) sensors to the continuous monitoring of the tire pressure in road vehicles. With these, the tire pressure can be read out in every phase of driving. We show the implemented prototype setup for measurement of the tire pressure, the applied SAW sensors, improved versions and the interrogation setup. The problems in practical application are discussed. Experimental results measuring the tire pressure during test rides are presented.

Monitoring the tire pressure at cars using passive SAW sensors

We have developed a wireless SAW (Surface Acoustic Wave) pressure sensor operating in the pressure range from 0 Pa to 250 kPa. In order to minimize the temperature sensitivity the pressure sensor is based on an all quartz package, which has been designed with the Finite Element Method. The package of the pressure sensor consists of a diaphragm and a cover, both made of conventional Y-cut quartz. A blind-hole was structured into the sensor cover. By attaching the cover and the diaphragm with an epoxy-adhesive, this blind-hole forms a closed cavity. The SAW element is a reflective delay line, working at approximately 434 MHz. The delay line consists of ten reflectors and extends over the whole diaphragm. The pressure is determined by evaluating the change of the carrier phase shifts of the reflected impulses at the reflectors. We show that it is possible to minimize the temperature sensitivity and to achieve good linearity by correct positioning of the SAW reflectors. The measurements of the SAW pressure sensor show a deviation from linearity of less than +/-0.7%. The temperature dependence is almost negligible in the range from -20/spl deg/C to 100/spl deg/C.

Franz Seifert

Papers

Passive surface wave sensor which can be wirelessly interrogated

Mechanical sensors based on surface acoustic waves

SAW devices as wireless passive sensors

Monitoring the tire pressure at cars using passive SAW sensors

Quartz pressure sensor based on SAW reflective delay line