Incremental printing of symbolic information – Thermal marking apparatus or processes
Reexamination Certificate
1999-12-21
2002-04-30
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Reexamination Certificate
active
06380962
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ray applying device. More particularly, the present invention relates to a ray applying device for applying such electromagnetic rays as visible light or ultraviolet rays to an object, typically used in a color thermal printer or an image reader apparatus.
2. Description Related to the Prior Art
A color thermal printer is used with a color thermosensitive recording material, which includes a support and three thermosensitive coloring layers of cyan, magenta and yellow colors formed thereon to be used for full-color printing. The yellow coloring layer is the farthest from the support, and has the highest heat sensitivity. The cyan coloring layer is the nearest to the support, and has the lowest heat sensitivity. The yellow and magenta coloring layers have fixability in response to application of ultraviolet rays of particular wavelengths. The thermal printer incorporates a thermal head and an illuminating device or ray applying device. While the recording material is conveyed in forward and backward directions, the thermal head presses the recording material and applies heat to the coloring layers for thermal recording. After application of the heat, the ray applying device including an ultraviolet lamp is driven to apply the ultraviolet rays to the recording material, for fixing an overlaid coloring layer each time before an underlaid coloring layer is colored.
Optical apparatuses such as a scanner, a telefacsimile machine and a copying machine incorporate the ray applying device for illuminating an original sheet and an image reader device for reading an image of the original sheet. In such an apparatus, the original sheet is conveyed in a manner relative, to the ray applying device and the image reader device, and illuminated by the ray applying device in the conveyance. The light reflected by the surface of the original sheet is focused on an image sensor, which reads an image of the original sheet by one line according to photoelectric conversion pixel by pixel. An example of the ray applying device is a fluorescent lamp, which is the ultraviolet lamp of a tubular shape and disposed perpendicularly to the direction of the relative conveyance of the original sheet or the image reader device.
A good example of the light source used in the ray applying device in each apparatus is the ultraviolet lamp in the tubular shape. The ultraviolet lamp has a circular shape as viewed in cross section, and emits the ultraviolet rays or visible rays in any radial directions at an equal intensity. In order to change the paths of the ultraviolet rays or visible rays emitted in directions different from the original sheet or the recording material, a reflector is disposed behind the ultraviolet lamp for efficiently reflecting this part of the ultraviolet rays or visible rays.
In the ray applying device having the ultraviolet lamp and the reflector, however, a sufficient space is required between the ultraviolet lamp and the reflector for the purpose of reflecting the light effectively toward the object by the reflector. The space causes the ray applying device to have a considerable size, and inconsistent to reduce the size of the apparatus incorporating the ray applying device. In the thermal printer in particular, an increase in the conveyed distance of he recording material lowers the speed of printing, and increases an area of margins. Also, the sufficient distance between the fixer and the recording material causes a problem in shortage in the fixation.
Another problem lies in that the ray emission intensity of the ultraviolet lamp in the tubular shape is different between its portions. In general, end portions of the ultraviolet lamp emit rays at lower intensity than its middle portion. The ultraviolet rays in the thermal printer cannot be applied uniformly to the recording material, so that unevenness occurs in fixation. Also a problem arises in a scanner, a telefacsimile machine or a copying machine in that unevenness occurs in brightness in the image read by the image reader device.
SUMMARY OF THE INVENTION
In view of the foregoing problems, an object of the present invention is to provide a ray applying device for applying electromagnetic rays to an object at an irradiance kept uniform on its object surface.
In order to achieve the above and other objects and advantages of this invention, a ray applying device applies electromagnetic rays to an object surface of a target object, the object surface extending two-dimensionally in main and sub scan directions. A surface light source extends in the main scan direction, for emitting the electromagnetic rays.
Furthermore, a filter is disposed in front of the surface light source, for shifting a ray emission center wavelength of the surface light source.
The electromagnetic rays are visible or ultraviolet.
In a preferred embodiment, the surface light source comprises at least one light-emitting display panel.
The light-emitting display panel has a size larger than the target object in relation to the main scan direction.
In another preferred embodiment, there is a ray applying station for setting the target object so as to dispose the object surface at a predetermined distance from the light-emitting display panel. The light-emitting display panel includes a middle portion disposed substantially in a middle in the main scan direction. There are two end portions between which the middle portion is disposed, and in which emission intensity of the electromagnetic rays is preset higher than in the middle portion in consideration of the predetermined distance, so as to provide the object surface with irradiance equal to irradiance with which the electromagnetic rays from the middle portion provides the object surface.
The end portions have a greater size in the sub scan direction than the middle portion, for increasing the emission intensity.
In still another preferred embodiment, the light-emitting display panel includes a panel body. A fluorescent film is disposed on an inside of the panel body. The end portions have the fluorescent film at a greater thickness than the middle portion, for increasing the emission intensity.
The target object is thermosensitive recording material, and the electromagnetic rays optically fix the thermosensitive recording material.
In one aspect of the present invention, the at least one light-emitting display panel is an array of plural light-emitting display panels arranged in the main scan direction.
The middle portion and the end portions are a middle light-emitting display panel and end light-emitting display panels among the plural light-emitting display panels. Furthermore, a light source driver drives the plural light-emitting display panels, for providing the end light-emitting display panels with first energy, and for providing the middle light-emitting display panel with second energy, the first energy being higher than the second energy, for increasing the emission intensity at the end light-emitting display panels.
In another preferred embodiment, the middle portion and the end portions are a middle light-emitting display panel and end light-emitting display panels among the plural light-emitting display panels. The end light-emitting display panels have a greater size in the sub scan direction than the middle light-emitting display panel, for increasing the emission intensity.
In another aspect of the present invention, the at least one light-emitting display panel is a group of plural light-emitting display panels arranged in plural lines extending in the main scan direction and in plural columns extending in the sub scan direction.
In still another preferred embodiment, the plural light-emitting display panels are arranged in a matrix manner. Furthermore, a light source driver drives selected ones of the plural light-emitting display panels. The selected light-emitting display panels includes at least one, P middle light-emitting display panel, disposed in a middle column among the plural columns, for constit
Feggins K.
Fuji Photo Film Co. , Ltd.
Le N.
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