Abstract: An electronic anti-shoplifting system monitors articles of merchandise in a sales outlet to deter shoplifting. The system is provided with transponder tags connected to the articles of merchandise. A tag exciter is positioned at an exit leading from the sales outlet and generates an RF surveillance excitation signal. If a customer carries an article through the exit without removal authorization due to failure to pay for the article, the transponder tag is activated, being powered by the RF surveillance excitation signal as the customer passes the tag exciter. The activated transponder tag generates an RF surveillance response signal that triggers an alarm. If the customer has removal authorization as the result of paying for the article, the transponder tag is reprogrammed to modify the operational data stored therein.

Abstract: An RF transponder system is provided that is capable of detecting and correcting data transmission errors. The RF transponder system includes an exciter that generates an RF excitation signal and a transponder that receives the RF excitation signal and is powered thereby. The transponder generates and transmits a RF response signal including a plurality of data sets each containing a common message. At least one of the data sets is encoded in a manner different from the remaining data sets. The RF response signal is received by a reader that decodes the encoded data sets. Corresponding bits of each of the data sets are compared for purposes of error detection. If a majority of corresponding bits from each of the data sets match, a valid bit is defined thereby. Bits that are not in the majority are discarded. An invalid bit is defined where less than a majority of corresponding bits match a selected bit of a selected data set.

Abstract: An RF transponder transmits information on the distance traveled by a wheeled vehicle in response to an interrogation signal from an exciter/receiver. A rotation sensor, preferably an odometer/shaft encoder combination that is mounted on a vehicle wheel, provides to the transponder a signal which indicates the distance traveled by the vehicle; the transponder is also preferably mounted to the wheel's rotational hub. The transponder preferably includes a memory with a reprogrammable portion that stores the sensor information, and a non-reprogrammable portion that stores an identification code, all of which is read out in response to an interrogation signal. Driving distances can be obtained automatically without having to read the vehicle's dash board odometer.

Abstract: A digital micromirror device projection system employs an array of digitally operable micromirrors that are individually and selectively tiltable between ON and OFF positions. The array of mirrors is illuminated by a high intensity light source, and light reflected from those mirrors selectively driven to the ON tilted position is reflected to a projection lens for projection onto a screen. Concomitantly, light reflected from those of the mirrors in the OFF position are blocked by a system stop. The system stop is formed by a wedge-shaped bundle of optical fibers positioned immediately adjacent the mirror array. The fiber axes are all mutually parallel and are perpendicular to the mutually parallel planes of those of the mirrors that are tilted to the ON position so that the illuminating light is incident upon the mirrors in a perpendicular relationship and is retroreflected back through the optical fibers to the projection lens of the system.

Abstract: A novel rear projection screen that displays images with substantially uniform brightness over a wider field-of-view than prior rear projection screens, comprising a first diffusing assembly for diffusing the image and a second diffusing assembly for further diffusing the image from the first diffuser. In the preferred embodiment, the first and second diffusing assemblies comprise an input diffusing screen and a fiber optic array, respectively, with an output diffusing screen used at the output end of the fiber optic array. A preferred flat panel tiled display system that incorporates the present invention includes a plurality of collimated light sources, with respective liquid crystal display assemblies that impart images onto the collimated light beams. An imager images the image-bearing light beams onto the rear projection screen described above so that they are displayed in a tiled arrangement.

Abstract: A transponder system employs a transponder antenna with a distributed inductance and capacitance that exhibit parallel and series resonant frequencies. Transmissions to the transponder circuit are made at one or more parallel resonant frequencies to maximize the excitation of the transponder circuit, while return signals transmitted back from the transponder are modulated at one or more series resonant frequencies to maximize the signal current. The transponder antenna is implemented as a pair of aligned coils on opposite sides of a thin dielectric substrate, with the coils connected together through the substrate at one point and the substrate thickness not more than about 25 microns to obtain a significant mutual inductance between the coils.

Abstract: The drive voltage (V.sub.DATA -V.sub.REF) across an active matrix liquid crystal display module (24) is reversed on alternate frames or alternate lines by using a fixed voltage level (V.sub.REF) at one side of the LCD module and shifting the level of a base component (V.sub.BASE) on the other side of the module between higher and lower voltage levels that are respectively higher than the fixed reference level and lower than the fixed reference level. All voltages have the same polarity so that polarity shifting of any applied voltage is not required. An intensity level component from a digital to analog converter (40a), controlled by a digital input code (41), is combined with the base component in the same sense in alternate frames, but with the digital input code inverted in alternate frames.

Abstract: A flat panel liquid crystal display module (34) has its front face adjacent a rear projection screen (40) and is illuminated by a pre-polarized collimated light source (10,14,16,18,22,26). Collimation is provided by either a Fresnel lens or a projection lens having a long focal length. The characteristics of the projection screen (40) provide narrowed vertical viewing angle and a fiber optic face plate (38) between the liquid crystal module (34) and the screen (40) provides sunlight rejection. The arrangement has greatly improved display brightness, with only minimal changes in contrast and color as viewing angle changes.

Abstract: Phosphor color screens with triad pitches of 150 .mu.m and less are fabricated by a combination of modified microelectronic processing techniques and electrophoretic coating of the phosphors and black screen. Indeed, triad pitches based on 15 .mu.m color line width and 5 .mu.m black matrix between colors are achievable.

Abstract: A transponder is formed of a very thin flexible substrate (10) on opposite sides of which are formed first (26) and second (31) series connected halves of a single antenna coil having ends connected to an integrated circuit die (50) mounted to a corner of the substrate. A plurality of bond pads (12a-12e) and programming pads (14a-14e) are also formed on the substrate and operatively connected to couple the antenna coils and the programming pads through the bond pads to the integrated circuit die. Unique configurations and arrangements of a die mounting site (46), bond pads (12a-12e), program pads (14a-14e), and vias (22,24) through the substrate enable an inexpensive simple construction. Protective laminates (58,60) on either side of the substrate are bonded to one another around the edges that circumscribe the substrate and also are bonded to one another at interior portions through a slot (20) formed in the substrate.

Abstract: A projection system having a rear projection screen (28) employs a collimating lens (26) in the form of a Fresnel lens adjacent the rear surface of the screen (28) to improve the image luminance at various viewing angles and provide uniform brightness over the area of the screen. A fiber optic face plate (30) or two crossed films of microlouver light control material is interposed between the collimating Fresnel lens (26) and the rear of the projection screen (28) to provide a high degree of blocking of high intensity light, such as sunlight, that may impinge upon the front of the screen. The optical fibers (42) of the fiber optic face plate have a low numerical aperture and an opaque cladding. The arrangement allows an image to be provided on the screen with high contrast even in the presence of sunlight striking the screen.

Abstract: An RF transponder couples the outer end of a coiled antenna winding to a transponder circuit located inside the winding by a lead line that crosses over the winding turns and is separated from the winding by a dielectric material. The width of the lead line is substantially greater than the antenna line width, yielding capacitances at the cross-over sites that establish a resonant frequency for communicating with the transponder circuit at a predetermined RF frequency. An optional discrete capacitor can also be used to boost the capacitance to a desired level. All of the transponder components are formed on one side of a flexible substrate, the opposite side of which is coated with an adhesive that is covered by a peel-off sheet, allowing the transponder to be affixed to packages as part of a package identification system.

Abstract: A tire transponder system seats a transponder coil in a flexible resilient tube that is positioned around a vehicle wheel. The transponder antenna is lodged in a groove that extends around the tube, and responds to an excitation signal by transmitting a signal that contains identification information and/or information on the tire condition. For tire condition information, a diode is connected in circuit with the transponder coil to double the frequency of the signal returned by the transponder. A switch that is connected to bypass the diode is operated by a tire condition sensor, such as a pressure sensor, when the sensed condition crosses a threshold level in a predetermined direction. The change in the frequency of the transponder's returned signal when the threshold has been crossed is used to activate a response such as a low tire pressure alarm.

Abstract: RF communication through an RF barrier is facilitated by an RF field concentrating core that is lodged within an opening through the barrier and extends out from at least one side of the barrier. An antenna coil is wound around the core, with a capacitor connected across the coil to establish a parallel resonant circuit at the exciting frequency. The core/coil combination provides a bidirectional RF coupler for transmitting signals between opposite sides of the barrier. It is particularly useful for transponder systems in which a transponder is located within an RF-blocking enclosure, and is interrogated by an exciter/reader outside the enclosure.