Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-12-21
2001-03-27
Le, N. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S115000, C347S122000
Reexamination Certificate
active
06208365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a vacuum fluorescent printer with a print head including luminous blocks each having a plurality of luminous elements arranged in a main scanning direction for emitting, to a photosensitive material, light released by applying electrons to phosphorous objects based on a drive signal, thereby forming dots on the photosensitive material, the luminous blocks and photosensitive material being movable relative to each other in a sub-scanning direction to form images based on image data on the photosensitive material.
2. Description of the Related Art
A fluorescent printer for forming images on a photosensitive material is disclosed in Japanese Patent Laying-Open Publication H5-92622 (corresponding to U.S. Pat. No. 5,592,205), for example. This printer has cathodes for releasing thermions, grid electrodes, and a plurality of strip-like anodes 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 control signals based on image data to the grid electrodes. Each phosphorous object corresponds to one pixel of an image, i.e. one dot. The luminous blocks have numerous phosphorous objects arranged in a main scanning direction. A latent image which is a combination of numerous dots based on image data is formed on the photosensitive material by a relative movement in a sub-scanning direction (at right angles to the main scanning direction) between the luminous blocks and photosensitive material. A color fluorescent printer for printing color images includes a print head having a read (R) luminous block, a green (G) luminous block and a blue (B) luminous block. A monochromatic fluorescent print for printing monochromatic images includes a print head having a single luminous block.
In a fluorescent printer which develops and transfers to transfer paper a latent image formed on a photoreceptor drum by light dots emitted from the luminous elements synchronously with rotation of the photoreceptor drum, sensitivity characteristics of the photoreceptor drum may be maintained at a constant high sensitivity level. Where, for example, the fluorescent printer is used for exposing a photosensitive material such as photographic printing paper exposed by a light source such as a halogen lamp providing a large quantity of light, it is necessary to expose the photosensitive material over a long period of time since each phosphorous object emits light in a rather small quantity. In addition, the sensitivity characteristics are greatly variable with different types of printing paper. Printing paper with low sensitivity characteristics requires a long exposure time. This is because there is a limitation to an increase in the quantity of light based on an increase in anode voltage, and it is difficult to adjust the quantity of light only by adjusting the anode voltage. Especially in the case of color printing paper, a particular color among R, G and B could have far lower sensitivity characteristics than the other colors. When the fluorescent printer is adjusted to the low sensitivity characteristics, printing performance is greatly reduced with a prolonged exposure time.
Further, in view of the sensitivity characteristics variable with different types of photographic printing paper, it is conceivable to combine the luminous blocks with suitable filters to adjust the quantity of light. However, this would require numerous filters to produce an optimal quantity of light for each different type of printing paper with varied sensitivity characteristics, and its adjusting operation would be troublesome. A further disadvantage is that, whenever a new type of printing paper is employed, a filter suited thereto must be provided.
SUMMARY OF THE INVENTION
The object of this invention is to provide, in connection with a vaccum fluorescent printer as noted above, a simple construction for setting an optimal quantity of light for numerous types of photosensitive materials requiring adjustment in the quantity of light.
In a first proposal made according to this invention to fulfill the above object, an additional luminous block is provided which is spaced from a luminous block in a sub-scanning direction, one monochromatic dot being formed by light from these luminous blocks.
With this construction, one dot formed by a luminous element in a predetermined position of one luminous block according to conventional practice is now formed by luminous elements in predetermined positions of a plurality of luminous blocks. Where, for example, two similar luminous blocks are provided, one dot may be exposed with twice the quantity of light. This is advantageous when using a photosensitive material having low sensitivity characteristics. Moreover, since a plurality of luminous blocks are arranged in the sub-scanning direction, emission timing of these luminous blocks may be properly adjusted to movement thereof in the sub-scanning direction relative to the photosensitive material. In this way, the same dot is exposed successively by luminous elements in predetermined positions of the plurality of luminous blocks. A majority of exposure areas may be exposed simultaneously by multiple exposure. Thus, hardly any reduction occurs in printing capability.
The above advantage of this invention is derived also from a vacuum fluorescent color printer with a print head including three RGB color luminous blocks each having a plurality of luminous elements arranged in a main scanning direction for irradiating a photosensitive material with light released from phosphorous objects to which electrons are applied based on a drive signal, thereby forming dots on the photosensitive material. For this purpose, such a color fluorescent printer has a plurality of luminous blocks arranged in the sub-scanning direction for printing at least one color among the three colors. Each dot of that particular color is formed by light from these luminous blocks. That is, at least one of the RGB color luminous blocks required to emit an increased quantity of light is accompanied by an additional luminous block. For that one color, exposure may be made with a quantity of light plural times that emitted from a single luminous block. The exposure by the plurality of luminous blocks may be performed during one relative movement in the sub-scanning direction.
In a preferred embodiment of this invention, a proposal is made to supply the plurality of luminous blocks with the same density data. Then, the density data transmitted to one luminous block may be forwarded intact to the other luminous block. It is necessary only to drive the luminous elements in timed relationship to the relative movement, which requires no great alteration to a printer controller. As a result, a quantity of light used in exposing one dot is a multiple depending on the number of luminous blocks added. It is of course possible to achieve a precise light emission quantity adjustment by supplying the plurality of luminous blocks with different density data though this would require a complicated printer controller.
As a preferred embodiment of this invention for realizing a quantity of light emission other than a multiple of a standard quantity, it is proposed to apply different voltages to anodes of the plurality of luminous blocks for the same color. Then, even when the same density data is used, one dot may be exposed with a quantity of light which is not simply a multiple of the standard quantity.
In a further preferred embodiment of this invention, a paper sensor is provided for detecting a type of printing paper acting as the photosensitive material. When a result of detection by the paper sensor indicates that the printing paper to be printed has high sensitivity characteristics, for example, a printing operation may be carried out using only one of the luminous blocks of the same type. When the printing paper has low sens
Morishima Hiromichi
Nakamura Shigetaka
Tsuji Hidekazu
Fulbright & Jaworski LLP
Le N.
Nguyen Lamson D.
Noritsu Koki Co.
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