Minnesota Mining and Manufacturing Company

3m Innovative Properties Company

Dwight G Baldwin

James M Nelson

Joseph Clark Carls

Charles N DeVore

Stephen K Eckhardt

Ernesto M Rodriguez

James K Kennedy

James E Peterson

Steven G Saxe

Xiaowei Zhao

Mike E Darland

An optical component array and method of making an optical component array includes a plurality of optical components useful for projection devices or other optical devices.

Method of making a polarizing beamsplitter array

The present disclosure provides an optical component array and method of making an optical component array that can include a plurality of optical components useful for projection devices or other optical devices. The optical component array can be fabricated such that individual optical components having several elements can be assembled in a massively parallel manner and then singulated as individual optical components, and can result in a large reduction in manufacturing cost.

Optical component array

Low profile overhead projector having a foldable post

An overhead projector including a stage assembly, a post extending from the stage assembly and an optical projection head assembly suspended above the stage assembly by the post in a cantilever arrangement, the optical head assembly having a weight W. The head assembly includes a post retaining assembly having a collar fitted around the post, the collar having at least two friction points interacting with the post, the interaction having a coefficient of friction &mgr;. The weight W and the cantilever arrangement create torsional forces, the at least two friction points being positioned to transmit the torsional forces onto the post creating a friction force F . The coefficient of friction of the interaction between each of the at least two friction points and the post is selected such that absent other forces the friction force is at least sufficient to maintain the head assembly at a static position with respect to the post.

Overhead projection having a friction secured adjustable cantilevered head

A condenser lens for a projection system optimizes the amount of overall brightness directed toward an aperture and the uniformity of illumination at the aperture. The lens, when placed in the projection system, has a marginal ray which starts at the center of the light source, passes through the edge of the condenser lens, and intersects the region to be illuminated at or near its edge. The lens further has a relative zonal ray height which is selected based on the distance from the light source to the aperture. The condensing lens system is particularly useful in the construction of overhead projectors.

Condensers for illumination systems

An improved overhead projector head is provided that reduces the vibration that can occur in an overhead projector head that is used to project images from an LCD panel placed on the stage of the projector. The improvements comprise adding a mounting plate between the support arm and the head bracket. The mounting plate is cantilevered from the support arm, and the head bracket is supported by spacers placed near the end of the mounting plate that is remote from the support arm. In alternative embodiments, the head bracket may be divided into two pieces separated by foam or other vibration damping material, or a conterweight may be added to the head assembly behind the support arm.

Overhead projector with vibration control head

An apparatus for reading an optical bar code on a transparent film uses a linear array of light sources and a linear, solid-state sensor located parallel with array. LED's are energized selectively in groups to avoid overlapping shadows on the sensor. A novel algorithm is used to reconstruct the shadowgraphs or image segments by searching for a transition (mark/space edge in the bar code) in an overlap zone at the boundary of adjacent segments on the sensor. Conventional techniques are then used to decode the reconstructed electronic image of the bar code. The apparatus is particularly useful in an electronic presentation system wherein the numeric value of the bar code is an image reference number (IRN) which is used to access a host computer and display a graphic image associated with the IRN. A novel bi-directional protocol is also presented for providing communications between the optical reader and the host computer. The protocol directs the host computer to download all IRN's for a given presentation to the reader. The reader can then locally determine if a bar code on a card corresponds to a valid IRN in the current presentation. The protocol may be adapted to download certain display control information and send associated control signals to the host computer based on keyboard input at the reader.

Solid state optical reader with bi-directional protocol

A novel bar code and optical reader for scanning the same. The bar code consists of two parallel channels of marks and spaces representing bit sequences, a given bit in one sequence being associated with a bit in the other sequence, forming successive bit pairs. The data is encoded in the logical exclusive-or combination of the bit pairs. An alternating clock scheme is further used to encode the data, which limits the width of any mark or space to twice the minimum width. The optical reader includes two optical detectors connected to a microprocessor which records the time intervals between mark/space transitions in each channel. These time intervals are used to reconstruct the bit sequences in each channel; the bit sequences may then be correlated and the XOR operation performed, yielding the encoded data.

Two-channel XOR bar code and optical reader

A optical reader for scanning optical marks from a substrate. The reader employs a novel optical geometry to eliminate undesirable specular reflections from entering the optical detection system. A stage area is provided for receiving the substrate, the stage having a window through which an incident beam of light passes at an oblique angle with respect to the window. A retrocollection system is used to return reflections from the substrate to the optical assembly. By directing the beam at an oblique angle with respect to the window, specular reflections are not collected in the retrocollection system and thus are not received by the optical detection system. The invention also utilizes a permanent magnet, direct current motor for controlling a scanning mirror, and further has a motor control circuit for preventing the introduction of electrical noise from the motor during the scan. A sensor may be provided to detect the presence of the card on the stage and provide 'on demand' scanning.

Optical reader with power isolation

A method and system for preparing image access cards to be used with an image access system. The image access system utilizes a storage medium containing the images and a reference table which includes a series of reference numbers associated with the storage address of each image. The method of making the image access documents utilizes the steps of placing the images on the storage medium, assigning a reference number to each image, and constructing the reference table. Several variations in the construction of the image access document are available. A printer may be used to print a human readable representation of the image and a machine readable form of the reference number directly onto a supportive substrate. Preprinted cards may be provided with the machine readable reference numbers thereon, and the human readable representation may be printed by a printer, hand drawn, or applied by way of a sticker. Tags, such as adhesive labels or transparent envelopes, may have the reference number printed thereon and be used in conjunction with the substrate having the human readable representation. A system for preparing the foregoing constructions advantageously employs a processor running the card preparation software, a storage device, a keyboard, a display, and the printer.

Method of preparing an image access card

An image access, retrieval, and display system provides a simplified system for randomly accessing stored images. Image access documents having a human readable representation of an image and machine readable image access information are placed in an image access document reader which transmits the image access information to the image display system causing the image to be displayed.

Growing community of inventors

Austin, TX, United States of America

Dwight G Baldwin