Illumination – Illuminated scale or dial – Internal light source
Patent
1993-11-12
1996-08-06
Gromada, Denise L.
Illumination
Illuminated scale or dial
Internal light source
G01D 1128, G09F 1320
Patent
active
055440207
DESCRIPTION:
BRIEF SUMMARY
This invention relates to display devices and has particular but not exclusive reference to the construction of keyboards and the like.
It is an object of the invention to enable a symbol, character, image or the like to be displayed in conjunction with another display, or an observation window or the like, in such a way that the other display, or the observation window is normally required to be unobstructed and can be made with the greatest possible area.
One application of the present invention is in chart recorders and other devices, in which an instrument or recorder incorporates a window or is placed behind a window, through which it can be observed in normal operation. Such devices may be provided with operating buttons, keyboards and the like, for controlling or adjusting their operation, inputting an outputting information, and so on. Providing conventional push buttons, keyboards and the like will often either reduce the area available for the observation window or increase the overall size of the device. It is an object of the invention to provide for an auxiliary display, either forming part of an input-output system or simply as a display, which does not reduce the space available for the window and which when not in use does not obstruct the normal observation of what lies behind the window.
According to tone aspect of the present invention, a recording or measuring device or the like is provided with an observation window through which it can be observed in normal operation, and the window is provided with at least one display element having an operative state in which it is visible and an inoperative state in which it is substantially invisible.
According to another aspect of the present invention, a display device comprises a transparent substrate, for example a panel of transparent material, at least one symbol, character, image or the like provided on a surface of the substrate and normally substantially transparent and means for illuminating the display element with radiation to which the said element is responsive, for example visible or ultraviolet light, thereby to render the element visible.
According to a further aspect of the invention there is provided a keyboard device comprising a transparent panel, transparent circuit elements thereon defining a keyboard, at least one radiation-responsive display element forming part of or in register with at least one said circuit element, said display element being normally transparent, and a radiation source for selectively irradiating the display element thereby to render it visible for revealing the keyboard.
The display element may have an active response to the radiation, e.g. fluorescence, chemoluminescence, polarisation etc.
Conveniently, the display element is fluorescent, and is illuminated by radiation transmitted within the panel or substrate acing as a light guide.
Alternatively the display element may comprise a local change in composition, surface texture or other physical characteristic of the panel or substrate, such as to scatter or otherwise passively redirect light when illuminated and thereby to reveal the positions of the elements. To enhance transmission of the activating radiation from the substrate to the display element, the display element may be composed of a medium which etches or otherwise modifies the surface of the substrate.
Yet another possibility is the use of display elements responsive to an applied electrical stimulus e.g. liquid crystal elements rendered visible by an applied voltage.
The substrate is preferably provided with transparent electrical tracks or circuit elements in predetermined relationship with the display element or elements, and forming part of a keyboard or the like, all composed of electrically conductive substantially transparent material, for example indium tin oxide (ITO), to form a keyboard or the like which is normally invisible but can be rendered visible, in effect, e.g. by application of radiation to activate the display element or elements, so that the display elements reveal
REFERENCES:
patent: 2594903 (1952-04-01), Freedman et al.
patent: 2931117 (1960-04-01), Bosworth et al.
patent: 3363257 (1968-01-01), Dewey et al.
patent: 5075826 (1991-12-01), Lan
Medizintechnik, vol. 29, No. 2, 1989, Berlin DD, pp. 58-59; Von Holger Zorn `Mehrkanalige Langzeitregistrierung Langsamverlaufender Fuktionen`.
Hurst, deceased Peter W.
Hurst, legal representative George R.
Loeber Peter J.
Eurotherm Recorders Limited
Gromada Denise L.
Raab Sara Sachie
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