Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-09-29
2001-06-05
Le, N. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S122000
Reexamination Certificate
active
06243122
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a vacuum fluorescent print head for printing paper having luminous elements with phosphorous objects which emits light beams to the printing paper based on image data, the luminous elements being arranged zigzag and in a plurality of columns extending in a main scanning direction.
2. Description of the Related Art
A print head for use on a fluorescent printer for forming color images on a photosensitive medium is disclosed in U.S. Pat. No. 5,592,205 (corresponding to Japanese Patent Laying-Open Publication H5-92622), for example. This print head has filamentary electrodes acting as cathodes for releasing thermions, control electrodes, and a plurality of strip-like anode electrodes covered by phosphorous objects of a predetermined size arranged at predetermined intervals, all sealed in a vacuum case. Thermion impingement upon the phosphorous objects, i.e. light emission from the phosphorous objects, is controlled by applying a voltage to the strip-like anode electrodes and applying control signals based on image data to the control electrodes. Each phosphorous object corresponds to one pixel of an image, i.e. one dot. The phosphorous objects must be arranged close to one another to obtain high resolution. However, it is essential that the phosphorous objects are spaced from one another. It is thus necessary to arrange the phosphorous objects zigzag and in a plurality of columns extending in the main scanning direction, such that the intervals between the phosphorous objects in each column are covered by the phosphorous objects in another column.
In the above print head having the phosphorous objects arranged zigzag and in a plurality of columns, the phosphorous objects in one column partially overlap the phosphorous objects in another column in order to avoid gaps occurring, in a sub-scanning direction at right angles to the main scanning direction, between light beam dots formed on the photosensitive medium by the phosphorous objects. Such a print head is effective as a writing head for an electronic copier, for example. However, when used in a digital exposing apparatus for processing photographic printing paper, such a print head causes double exposure where the light beams overlap one another on the printing paper. The overlapping positions have increased density, resulting in stripes due to density variations from dot to dot on the printing paper.
SUMMARY OF THE INVENTION
The object of this invention is to provide a fluorescent print head for printing paper which forms no stripes due to density variations from dot to dot on printing paper even where a print head construction is employed which has luminous elements with phosphorous objects arranged linearly in a plurality of columns extending in a main scanning direction and arranged in a sub-scanning direction at right angles to the main scanning direction.
The above object is fulfilled, according to this invention, by a vacuum fluorescent print head for photographic printing paper having luminous elements with phosphorous objects arranged linearly in a main scanning direction to form a plurality of luminous element arrays arranged in a sub-scanning direction at right angles to the main scanning direction, characterized in that the luminous elements of the luminous element arrays are arranged at predetermined intervals, and the luminous element arrays are arranged relative to one another, such that light beams radiating from the luminous elements of one of the luminous element arrays and from the luminous elements of another of luminous element arrays lie close to one another without overlapping in the sub-scanning direction.
This construction effectively avoids a situation where adjacent dots formed on printing paper are double-exposed by adjacent luminous elements. Preferably, an adjacent pair of dots formed on the printing paper by the luminous elements of the plurality of luminous element arrays have a gap of approximately 0.1 to 0.3 &mgr;m formed therebetween, even where, for example, resolution is approximately 200 dpi, i.e. each dot has a width of approximately 0.12 mm. This suppresses double exposure and achieves prints with no noticeable stripes due to density variations. White color in an image on printing paper is far less conspicuous to the eye than black color. In view of this fact, the above feature is achieved by utilizing the exposure characteristic of printing paper that weakly exposed areas come out in white color.
To obtain light beams as noted above, one preferred embodiment of this invention provides a vacuum fluorescent print head for photographic printing paper comprising a translucent substrate, a first strip-like anode conductor and a second strip-like anode conductor formed on an inner surface of the substrate to extend parallel to a main scanning direction, phosphorous objects covering a plurality of through-holes formed in both of the strip-like anode conductors, control electrodes and filamentary cathodes spaced from the phosphorous objects, and color filters and lenses arranged on an outer surface of the substrate and opposed to the phosphorous objects, wherein the through-holes of the first strip-like anode conductor and the through-holes of the second strip-like anode conductor are arranged zigzag, and close to one another without overlapping in a sub-scanning direction at right angles to the main scanning direction. With this construction, the light beams radiating from the phosphorous objects as a result of impingement thereon of thermions travel through the through-holes, color filters and lenses to the printing paper. The above characteristic arrangement of through-holes effectively avoids overlapping of light beam dots, thereby to produce photographic prints appealing to the eye.
In a different embodiment of the invention, a vacuum fluorescent print head for photographic printing paper comprises a shielding member, filamentary cathodes arranged inwardly of the shielding member, phosphorous objects arranged on an inner surface of the shielding member and covering a plurality of through-holes formed in the shielding member, and color filters and lenses arranged on an outer surface of the shielding member to cover the through-holes, wherein the through-holes are arranged zigzag to extend in a main scanning direction and to lie close to one another without overlapping in a sub-scanning direction at right angles to the main scanning direction. With this construction also, the light beams radiating from the phosphorous objects and traveling through the through-holes, color filters and lenses to the printing paper form dots not overlapping one another, to produce photographic prints appealing to the eye.
In each of the above embodiments, the through-holes arranged zigzag, preferably, have a gap of approximately 0.1 to 0.3 &mgr;m formed therebetween in the sub-scanning direction.
Other features and advantages of this invention will be apparent from the following description of the embodiments to be taken with reference to the drawings.
REFERENCES:
patent: 4578615 (1986-03-01), Genovese
patent: 4712909 (1987-12-01), Oshikoshi
patent: 4859913 (1989-08-01), Genovese
patent: 5592205 (1997-01-01), Shimizu
patent: 5592206 (1997-01-01), Watanabe
patent: 0160518 (1985-11-01), None
Patent Abstracts of Japan vol. 096, No. 007, Jul. 31, 1996 & JP 08067027 (Toshiba Corp), Mar. 12, 1996.
Morishima Hiromichi
Nakamura Shigetaka
Fulbright & Jaworski LLP
Le N.
Nguyen Lamson D.
Noritsu Koki Co., Ltd.
LandOfFree
Digital exposure apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Digital exposure apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Digital exposure apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2534893