Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-10-12
2003-10-28
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S173000, C345S179000
Reexamination Certificate
active
06639579
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetophoresis type display device which makes use of a magnetic field to make magnetic particles sealed in the display device magnetically float and display an object and to a process of production of the same.
2. Description of the Related Art
Known in the art for example are the magnetophoresis type monochrome display devices disclosed in Japanese Examined Patent Publication (Kokoku) No. 59-47676, Japanese Examined Patent Publication (Kokoku) No. 57-46439, and Japanese Utility Model Registration No. 1428562. In these magnetophoresis type monochrome display devices, the sealed space between the display panel sheet and the back panel sheet is divided into a large number of cells in which are sealed liquid dispersions containing black magnetic particles and a white fluid. By moving a recording magnetic member etc. (for example a “magnetic pen”) in contact with the outer surface of the front panel sheet, the black magnetic particles in the dispersion sealed in the cells corresponding to the path traced by that member magnetically float from the bottom to the front panel sheet side by the magnetic action of the member. As a result, some sort of monochrome display is formed by the difference in contrast between the white fluid and the black magnetic particles at the outer surface of the transparent front panel sheet.
Further, Japanese Examined Patent Publication (Kokoku) No. 8-7532 discloses the various conditions for the black magnetic particles in the liquid dispersion sealed in a magnetophoresis type monochrome display device for obtaining a good monochrome image display at the outer surface of the front panel sheet. Further, Japanese Unexamined Patent Publication (Kokai) No. 8-183291 discloses that the content of the black magnetic particles in the liquid dispersion sealed in the magnetophoresis type display device should be 15 to 20 parts by weight with respect to 100 parts by weight of the dispersion medium.
Further, recently, as shown in Japanese Unexamined Patent Publication (Kokai) No. 11-149265, Japanese Utility Model Registration No 3048929, and Japanese Utility Model Registration No. 3047170, magnetophoresis type color display devices able to display multiple colors have also been proposed.
In such magnetophoresis type display devices of the related art, it has been sought to eliminate the image breaks in display at the boundary portions of the individual cells and improve the black and white contrast or the color contrast.
In particular, in magnetophoresis type color display devices, a display device which is free from color bleeding, has clear hues, and can improve the resolution of the color display image has been sought.
In order to obtain a good image display at the outer surface of a front panel sheet, in particular to eliminate the image breaks in display at the boundary portions of the individual cells and improve the contrast of the display image and the resolution of the display image, however, it was made clear by experiments of the present inventors that it is not enough to specify certain conditions of the magnetic particles and, further, it is not enough to just define a certain content of the magnetic particles in the liquid dispersion.
Further, in the magnetophoresis type display devices of the related art, there was the problem of disposal since the front panel sheets were made of polyvinyl chloride. Further, in the process of production of magnetophoresis type display devices of the related art, the work of precisely filling the liquid dispersion containing the magnetic particles in the individual cells was difficult. The individual cells were liable to be either filled too much or too little with the liquid dispersion. Due to this, problems were liable to occur such as image breaks in the display at boundary portions of the individual cells or a reduction in the black and white contrast or color contrast.
SUMMARY OF THE INVENTION
The present invention was made in view of this situation and has as its first object to provide a magnetophoresis type display device which can display an excellent image at the front panel sheet, in particular can eliminate the image breaks in display at the boundary portions of the individual cells and can improve the contrast of the display image and the resolution of the display image.
Further, the present invention has as its second object to provide a magnetophoresis type color display device which can display a color image, in particular can eliminate the image breaks in display at the boundary portions of the individual cells, eliminate color bleeding, give clear hues, and improve the resolution of the color display image.
Further, the present invention has as its third object to provide a magnetophoresis type display device which is environmentally friendly at the time of disposal and further which can eliminate the image breaks in display at the boundary portions of the individual cells and can improve the contrast and a process for production of the same.
Still further, the present invention has as its fourth object to provide a process for production of a magnetophoresis type display device which facilitates the precise filling of a liquid dispersion containing magnetic particles in the individual cells and thereby enables the liquid dispersion to be filled in the individual cells without excess or shortage.
The present inventors engaged in intensive studies to achieve the first object and as a result discovered that by defining the effective magnetic flux densities at the panel surface due to the recording magnetic member and the erasing magnetic member and maintaining an overall predetermined relationship among the various conditions of the magnetic particles, the ratio of content of the magnetic particles in the liquid dispersion, etc. it was first possible to eliminate the image breaks in display at the boundary portions of the individual cells and improve the contrast of the display image and the resolution of the display image and thereby completed a first aspect of the present invention.
That is, according to the first aspect of the present invention, there is provided a magnetophoresis type display device (including magnetophoresis type color display device, same below) comprising:
a transparent front panel sheet,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space into a large number of cells,
a liquid dispersion containing magnetic particles to be sealed inside the cells formed by partitioning by the partitioning member,
a recording magnetic member provided to be able to move along the outer surface of the front panel sheet and having a magnetic force of an extent giving an effective magnetic flux density of 100 to 500 Gauss at the outer surface of the back panel sheet in the state when the recording magnetic member is brought into contact with the outer surface of the front panel sheet, and
an erasing magnetic member arranged at the outer surface of the back panel sheet and having a magnetic force of an extent giving an effective magnetic flux density of 100 to 1500 Gauss at the outer surface of the front panel sheet in the state when the erasing magnetic member is brought into contact with the outer surface of the back panel sheet.
When the magnetic force of the recording magnetic member and/or the erasing magnetic member is too small, the magnetophoresis action in the cells is weak, so the display/erasure at the display device tends to become difficult. Further, when the magnetic force is too large, the magnetic field is too strong, so even magnetic particles which should originally not be made to magnetically float end up magnetically floating and detract from the resolution of the displayed object at the screen.
Further, to achieve the first object, according to a second aspect of the present invention, there is provided a magnetophoresis
Imamura Kenji
Itou Takahiro
Nihira Yoshito
Alphonse Fritz
Oliff & Berridg,e PLC
Saras Steven
Takara Corporation Limited
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