Browse Prior Art Database

Compact Microprinter Based on a Small Passive Display

IP.com Disclosure Number: IPCOM000050735D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 4 page(s) / 43K

Publishing Venue

IBM

Related People

Barclay, DJ: AUTHOR [+4]

Abstract

Small displays can now be produced with very high resolution. These commonly employ passive technologies such as electrochromics or liquid crystals, and the display may be integrated on a semiconductor wafer. These small passive displays are highly suitable as original sources for the production of microfilm output, using suitable cameras, films and illumination systems. This article describes the construction and use of a prototype microprinter based on a preferred implementation comprising a miniature electrochromic matrix display for generating the variable image data to be printed. The display, which is integrated on a semiconductor wafer, is flash-illuminated and photographed through an appropriate optical system by a microfilm camera.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 42% of the total text.

Page 1 of 4

Compact Microprinter Based on a Small Passive Display

Small displays can now be produced with very high resolution. These commonly employ passive technologies such as electrochromics or liquid crystals, and the display may be integrated on a semiconductor wafer. These small passive displays are highly suitable as original sources for the production of microfilm output, using suitable cameras, films and illumination systems. This article describes the construction and use of a prototype microprinter based on a preferred implementation comprising a miniature electrochromic matrix display for generating the variable image data to be printed. The display, which is integrated on a semiconductor wafer, is flash-illuminated and photographed through an appropriate optical system by a microfilm camera. The printer also incorporates a heated platen development station for developing the microfilm which is of the dry silver halide type.

The internal construction of the prototype printer is shown in Fig. 1, and the external construction is shown in Fig. 2.

The image source for the printer is an electrochromic cell 10 mounted on a relocatable block 11. The cell includes an array of silver electrodes (not shown) formed on a silicon wafer which includes matrix-addressing circuitry. The electrolyte is an aqueous solution of an electrochromic diheptyl viologen salt which is reduced at energized electrodes to form a violet colored deposit.

The cell is illuminated by means of a flash tube 12 located in an elliptical concentrator 13, as shown in Fig. 3. The concentrator is flat on the non-elliptical faces, and the flash tube is inserted orthogonally to these flat faces at one focus of the ellipse. The concentrator is truncated at the other focus of the ellipse, orthogonally to the major axis. Light from the flash tube is delivered by the concentrator to a thick truncated wedge 14 forming one wall of the electrochromic cell. Light is directed by the wedge onto the base of the cell, and onto the array of silver electrodes. The electrodes scatter light out through the front face of the cell, forming the image in the appropriate plane. Estimates of light power transmission and computer simulation of ray paths indicate that the elliptical concentrator operates at a little over 10 percent efficiency. Attempts to increase this by silvering the ellipse were shown to be counter-productive since the illumination at the display surface became uneven.

Color filtration is also used to enhance the image contrast. The colored form of heptyl viologen, which is the basis of electrochromic displays using that material, has an absorption maximum around 550 nm. Since the film used is green sensitive the choice of a green filter is relatively straightforward. This and other considerations suggested the use of a narrow band Wratten 61 filter, shown as 15, which was positioned on the input face of the wedge 14.

A 55 mm f/2-8 Micro-Nikkor lens 16 was used to reduce the imag...