Projector Units Research Articles

The Effects of Manufacturing Inaccuracies in an Underwater Acoustic Projector Array on the Acoustic Interactions

We report on the importance of considering manufacturing inaccuracies in underwater acoustic projectors by elucidating how small variations affect the response characteristics of a projector array in the presence of mutual-loading effects. A wave-based distributed mechanical model accurately calculates the changes arising from small variations, so rapid changes occurring in the vicinity of the transducer resonance can be simulated. The results showed the effects of mutual loading between projector units and confirmed that the changes can be drastically intensified in the presence of manufacturing inaccuracies. A voltage adjustment method to compensate for these changes is also demonstrated as a solution. This framework could guide the design of projector arrays in sound navigation and ranging (SONAR) systems for a variety of applications and, in particular, may contribute significantly to determining manufacturing tolerances.

Glasses-free large-screen three-dimensional display and super multiview camera for highly realistic communication

We studied highly realistic communication systems using a super multiview three-dimensional (3-D) video system. We propose the developed glasses-free 200-in. 3-D display using ∼200 high-definition (HD) projector units to reconstruct natural life-size 3-D moving objects, such as cars and humans. We also analyzed the optimal arrangement of the multiview camera system for the 3-D display. In the experiments, we developed a prototype super multiview 3-D camera system using compact HD video cameras with real-time convergence compensation circuits that correct the captured images via image processing optimized for the display. We also performed demonstration experiments using the developed 3-D display and camera system in a public area. As a result, we highlight several possibilities for actual applications of the glasses-free super multiview 3-D video system.

Projector Phones

With the miniaturization of projection technology, the integration of tiny projection units into mobile devices is no longer fiction; therefore, such integrated projectors in mobile devices could make mobile projection ubiquitous. These phones will have the ability to project large-scale information onto any surfaces in the real world, and by doing so, the interaction space of the mobile device can be considerably expanded. In addition, physical objects in the environment can be augmented with additional information, which can support interaction concepts that are not even possible on modern desktop computers today. The authors believe that mobile camera-projector units can form a promising interface type for mobile Augmented Reality (AR) applications, thus, this paper identifies different application classes of such interfaces. In addition, different spatial setups of camera and projector units will have an effect on the possible applications and the interaction space with the focus on the augmentation of real word objects in the environment. This paper presents two examples of applications for mobile camera-projector units and different hardware prototypes that allow augmentation of real world objects.

Shock-resistant flextensional transducer

An underwater sonar projection includes a one piece hollow shell of elliptical cross section having a number of transducer stacks positioned within the shell and compressively prestressed by the shell to vibrate along the major axis thereof which causes the broad surfaces between the small radius ends to vibrate in and out. To resist large external shocks the shell is made somewhat heavier than usual, a center support member or beam is placed along the minor axis of the shell and an adjustable support rod is carried in the beam which is adjusted to a length just sufficient to clear the vibrating surfaces of the projector in normal operation but which functions to limit the inward movement of the shell if exposed to an explosion. The transducer stacks include a number of columns of piezoelectric disks on each side of the support beam which are bonded together, each stack having a tail member fastened to said center support beam and a head member between the disks and the end of the shell. To minimize damage to the disks, the stacks are wrapped with glass fiber cloth. Two or more such projector units may be fastened together and the ends closed by endplates.

AUDIO‐VISUAL AIDS

3M Audio Visual Products have added a new portable overhead projector, the Model 2000, to the recently introduced 2100 series of projector units. It weighs 15 pounds, is easy to operate and has excellent reliability. Being so light and of a compact and self‐contained design, it is very easy to carry and store away — an ideal projector for the trainer who moves around company locations. The attaché‐case portable converts easily into an A4 stage projector complete with a marker/pointer tray and readily accessible spare lamp compartment. A scratch‐resistant Fresnel slate ensures that transparencies consistently project clear, sharp images. Because the lamp is cooled by convection, there is no fan noise to distract the audience's attention.

Now you see it

Last year over £250 million was spent on a burgeoning variety of audio‐visual equipment and services — everything from overhead projector units to multi‐media presentations. A—V in management and training set the pattern for this growth.