Minnesota Mining and Manufacturing Company

Si Diamond Technology, Inc.

Michael C Sweaton

Zvi Yaniv

Alexei Tikhonski

James K Kennedy

Gary L Tritle

An image projection system comprises an image projector, such as a film or television projector and a projection screen. The projection screen is fabricated of a substantially transparent material, such as glass or plastic. The screen of transparent material has one or more areas or portions formed therein which areas or portions may be made to be translucent upon the application of a stimulus. Once in a translucent condition, the projected image can be received and viewed on the translucent portion. A mirror can be positioned behind the projection screen so that a person can view the reflection of themselves in the mirror when the screen is transparent, and an image can be projected when the projection screen is made to be substantially translucent.

Shutter for image projection system

A method and system for projecting an image. An image projection system may include a sensor configured to detect the presence of an observer within a proximity of a medium, e.g., screen, window. In response to the sensor detecting the presence of an observer within a proximity of the medium, one or more portions of the medium may be switched from a transparent state to a substantially translucent state. At a substantially concurrent time as switching the one or more portions of the medium to a substantially translucent state, an image may be projected onto such portion(s). Hence, an image may be displayed in response to detecting an observer within the proximity of the medium.

Displaying an image based on proximity of observer

A power supply is provided for a presentation system having a light source which allows for overdriving of the light source, but protects against transient surges on the input line when overdriving the light source. The power supply includes an input line connected to the external ac source, two output lines, and a relay selectively connecting the input line to one of the two output lines. The relay is indirectly controlled by a voltage sense circuit which converts the ac source voltage to a dc output voltage. The dc output voltage is examined to determine whether the input line is in a low- or high-voltage state, the high-voltage state corresponding to a surge on the line. The output lines are coupled to the load line (leading to the light source) in such a manner that the ac voltage source, when applied to the first output line, will produce a lower voltage at the lamp than that produced when the ac voltage source is applied to the second output line, thus overdriving the lamp when the relay connects the input line to the second output line. As long as the input line is not surging, i.e., while it is in the low-voltage state, the relay connects the input line to the second output line to allow for overdriving. When a surge is detected, the relay switches the input line to the first output line. The voltage sense circuit includes a hysteresis component which automatically adjusts the predetermined threshold to prevent constant switching of the voltage sense circuit output when there are only minor deviations in the voltage near the threshold.

Overvoltage protection circuit

An overhead projector (OHP) presentation system uses a liquid crystal display (LCD) panel to project electronically stored graphic images. The OHP preferably includes an integrated computer having a plurality of output ports for connection to various peripheral devices. A novel interface card is also used to provide electrical connections between the computer and the LCD panel, providing the further benefit of aligning the transmissive portion of the panel with the stage of the OHP. The LCD panel may be designed to swing horizontally into the optical path. This may be accomplished by providing a sliding drawer which inserts the panel within the body of the OHP, or by pivotally attaching the panel to the stage of the OHP.

Overhead projector for LCD panel

An overhead projector (OHP) presentation system uses a liquid crystal display (LCD) panel to project electronically stored graphic images. The OHP preferably includes an integrated computer having a plurality of output ports for connection to various peripheral devices. A novel interface card is also used to provide electrical connections between the computer and the LCD panel, providing the further benefit of aligning the transmissive portion of the panel with the stage of the overhead projector.

Growing community of inventors

Austin, TX, United States of America

Michael C Sweaton