Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-12-21
2001-09-18
Le, N. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S246000, C347S122000
Reexamination Certificate
active
06292209
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of testing light-emitting condition of a vacuum fluorescent print head. The invention relates more particularly to a method of testing light-emitting condition of a vacuum florescent print head of a type having a plurality of luminous elements disposed along a main scanning direction for forming dots in the form of a linear column on a print paper. For forming a planar image, i.e. an image having both a width and a length, from a plurality of linear dot columns juxtaposed with each other, the print head is movable in a sub-scanning direction relative to the print paper.
DESCRIPTION OF THE RELATED ART
A vacuum florescent print head of the above-noted type is known from e.g. U.S. Pat. Ser. No. 5,592,205. For testing of the light-emitting condition of the print head, the light-emitting amounts of the luminous elements are compared with each other. And, this is done through comparison of densities of the respective dot images obtained therefrom by exposing the dots on the print paper. In doing this, the conventional method is as follows. First, by driving the print head on the print paper along the main scanning direction, there is formed on the print paper a linear dot column, as such shown in
FIG. 7-
a,
consisting of a plurality of dots disposed linearly adjacent each other in the main scanning direction. Then, by scanning this dot column by using a line scanner or the like, the densities of the respective dots are obtained and outputted for the subsequent comparison therebetween as the test result of the light-emitting condition of the print head.
The above method has one problem due to the tendency of each dot exposing an area of the print paper greater than the diameter of phosphorous material or phosphor constituting the luminous element forming this dot, resulting in a partial overlap between outermost regions of adjacent dots on the print paper, as illustrated in
FIG. 7-
b.
Then, in the subsequent step of obtaining the density of each dot by using a scanner or the like for the purpose of testing the light-emitting condition, each dot will be affected by another dot adjacent thereto. Consequently, the light-emitting condition of each dot, i.e. the luminous element can not be grasped with satisfactory accuracy.
In view of the above-described state of the art, a primary object of the present invention is to overcome the above problem of the conventional method of testing light-emitting condition of a vacuum florescent print head by proposing an improved method which allows an operator to grasp the light-emitting condition of each luminous element with greater accuracy.
SUMMARY OF THE INVENTION
For accomplishing the above-noted object, according to the present invention, in a method of testing light-emitting condition of a vacuum fluorescent print head of the above-noted type, the method comprises:
a first step of exposing and forming on a print paper a plurality of linear dot columns, each column consisting of a plurality of dots arranged along a main scanning direction with a predetermined space therebetween, the plurality of dot columns being juxtaposed with each other with a predetermined space therebetween;
a second step of determining density of each dot formed and exposed by the first step one column after another by using a scanner; and
a third step of outputting the determined densities of the respective dots as light-emitting amounts of a plurality of luminous elements forming the linear dot column.
According to the method of the invention having the above-described construction, in each linear dot column formed by the first step, the respective dots belonging in this column are spaced apart from each other in a non-overlapping manner with a predetermined space therebetween, so that the densities of the respective dots may be obtained accurately without mutual interference therebetween. Further, the linear dot columns are spaced apart from each other also in the sub-scanning direction. Hence, in the second step, the scanning operation by the line scanner may be divided into a plurality of scanning operations of the respective columns. Then, with these scanning operations combined, the determination of dot densities may cover the entire dots. As a result, this construction helps to achieve the intended object of the invention, i.e. proposing an improved method which allows an operator to grasp the lightemitting condition of each luminous element with greater accuracy.
According to one preferred embodiment of the present invention, the plurality of dot columns formed in the first step includes a first column obtained by simultaneously exposing all of the luminous elements on the print head that are provided for forming odd-numbered pixels and a second column obtained by simultaneously exposing all of the other luminous elements that are provided for forming even-numbered pixels. With this construction, the entire dots needed for forming the linear dot columns by the luminous elements may be obtained by only two times of exposure operations. As a result, this construction achieves a more efficient method of testing light-emitting condition of a vacuum fluorescent print head.
Further and other features and advantages of this invention will be apparent from the following detailed description of a preferred embodiment thereof in conjunction with accompanying drawings.
REFERENCES:
patent: 5258778 (1993-11-01), Creutzmann et al.
patent: 5416613 (1995-05-01), Rolleston et al.
patent: 5586055 (1996-12-01), Ng et al.
patent: 5592205 (1997-01-01), Shimizu et al.
patent: 5818501 (1998-10-01), Ng et al.
patent: 0 713 328 A2 (1996-05-01), None
patent: 0 763 797 A2 (1997-03-01), None
Morishima Hiromichi
Nakamura Shigetaka
Fulbright & Jaworski LLP
Le N.
Nguyen Lamson D.
Noritsu Koki Co. Ltd
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