Browse Prior Art Database

One Dimension CRT Display Unit

IP.com Disclosure Number: IPCOM000088747D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Barrekette, ES: AUTHOR [+2]

Abstract

In the ROLED (rotating optical light-emitting diode) display, a line of LEDs is used as the source and a rotating optical element, such as mirror 5 shown in the figure, maps the line into a 2-D image space. The major advantage is that each LED is mapped into a column, thus the cost of a given LED is amortized over a column of spots. In doing this work, one finds that for certain low end applications, the cost of interconnecting to a line of LEDs is prohibitive. An alternative way of implementing this display is to use a 1-D cathode-ray tube (CRT) as the light source, as shown at 1 in the figure. The tube only needs one-dimensional deflection to replace the LED array.

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One Dimension CRT Display Unit

In the ROLED (rotating optical light-emitting diode) display, a line of LEDs is used as the source and a rotating optical element, such as mirror 5 shown in the figure, maps the line into a 2-D image space. The major advantage is that each LED is mapped into a column, thus the cost of a given LED is amortized over a column of spots. In doing this work, one finds that for certain low end applications, the cost of interconnecting to a line of LEDs is prohibitive. An alternative way of implementing this display is to use a 1-D cathode-ray tube (CRT) as the light source, as shown at 1 in the figure. The tube only needs one- dimensional deflection to replace the LED array.

Both the deflection and modulation of the beam can be very simple. One way of achieving the electron optics is to use a slit 3 to define the spot which eliminates some focusing electronics and turns the beam on and off just by deflecting the beam vertically by a small amount. Alternatively, a simple strip of phosphor may be used instead of sheet 3, and the beam may be turned on and off by vertical deflection.

The phosphor used must have a fast decay time. For example, if a column of n spots and 50 frame/sec is used, the decay time must be < 1/60n. For n = 200, the decay time is 80 x 10/-6/. The decay time of P-31 is ~40 x 10/-6/. Thus, by using a P-31 phosphor, approximately 400 spots may be obtained which is more than is needed for a ROLED type of display. Since it is...