GB2162355A

GB2162355A - Electro-optic unit

Info

Publication number: GB2162355A
Application number: GB8515107A
Authority: GB
Inventors: Rainer Fey
Original assignee: Huret et ses Fils SA
Current assignee: Huret et ses Fils SA
Priority date: 1984-06-15
Filing date: 1985-06-14
Publication date: 1986-01-29
Also published as: IT8567561A0; GB8515107D0; IT1183894B; DE3422273A1; FR2566157A1

Abstract

The optoelectronic structural unit includes a liquid crystal indicating element whose base plate projects laterally beyond a transparent cover plate that forms the view field and keyboard contacts printed on the surface of the base plate facing the cover plate and projecting beyond the cover plate. An elastic keying membrane carrying printed counter- contacts in the area of the printed contacts covers the printed contacts as well as the cover plate and is sealed to the base plate around the keyboard contacts and the cover plate to achieve a sealed indicating keyboard unit. In one embodiment, additional electronic components are mounted directly on the base plate between the membrane and the base plate 5 and connected to the keyboard contacts. Preferably the electronic components are microprocessor chips and/or solar cells which are connected to a pocket calculator module by means of conducting paths attached on the base plate of the indicating element. <IMAGE>

Description

SPECIFICATION Electro-optic unit BACKGROUND OF THE INVENTION: FIELD OF THE INVENTION: This invention relates to unitary electro-optic structures, and particularly to modules with liquid crystal indicators.

Liquid crystal indicating components are normally composed of two electrode-carrying glass plates which sandwich and enclose a liquid crystal substance between them to form an indicating element. One of the two plates is a carrier or base plate and the other is a cover plate which forms a view field. To complete the indicating element, the base plate extends laterally beyond the cover plate and and carries suitable contacts on the extended area to connect the liquid crystal indicating element to other components. Indicating elements or components of this type are then often combined with other components of this type are then often combined with other components such as keyboards to form conventional structural units such as pocket calculators. The indicating element and the keyboard are separately mounted on a frame or a housing and are separately connected.

Keyboards previously used with liquid crystal indicating elements have mechanically deflectable metal spring connectors or the like. Some keyboards with foil keying switches, or membrane keyboards, use base plates which carry electrically conducting contact segments on their surfaces. An elastic keying membrane of silicone rubber or other plastic, which carries disk-shaped counter-contact surface segments on inside surfaces of upwardly convex key or switching domes extend over the base plate. When depressed the switching domes press the counter-contact segments on the inner surface of the dome against the contact segments on the base plate and close the switches under the domes.

An object of the invention is to improve devices of this type.

Another object of the invention is to reduce the time and effort expended in assembling such electronic components and to increase their operating reliability.

SUMMARY OF THE INVENTION: According to the invention these and other objects are attained in whole or in part by forming the keying switches as a part of a membrane keyboard and arranging the keyboard's electrically-conducting surface-attached contact segments directly on the base plate of the liquid-crystal indicating element.

According to another feature of the invention the keyboard's contact segments are placed on the surface of the indicator element which faces the cover plate. The elastic keying membrane, which is provided with countercontact surface segments that respond to keying pressure, is fastened to the base plate of the liquid crystal indicating element and sealed in the area which peripherally encloses at least the contact segments.

Such a structure can be constructed and bonded as a unit. The keying switches are enclosed and sealed between the keying membrane and the liquid crystal indicating elements near the contact segments deposited on the base plate so counter contacts can be made to touch the contact segments on the base plate which is normally composed of glass. This provides for a high degree of operating reliability. According to an embodiment of the invention, the contact segments, together with the conductor paths and the like, of the liquid crystal indicating elements, are attached, and in particular vapor deposited, in one working cycle.

In preferred embodiments the keying membrane protects not only the surface-attached contact segments of the keying switches, but also the liquid crystal indicating element and any other electronic structural elements attached directly onto the base plate of the indicating element. In this way the structural unit is sealed in its entirety so as to be airtight and watertight. These additional structural elements are preferably a microprocessor chip or a solar cell for the supplying power to the pocket calculator module. This allows the calculator module to be operated independent of other systems and to be sealed in its entirety.

These and other features of the invention are pointed out in the claims. Other objects and advantages of the invention will become evident from the following detailed description of embodiments when read in light of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS: In the drawings: Figure 1 a partially broken open top view of a liquid crystal indicating element and keyboard module; Figure 2 a sectional view of the module along a line Il-Il in Fig. 1 and Figure 3 a partially broken open top view of a pocket calculator module which can be operated without connection to another system.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENTS: The indicating keyboard module shown in Figs. 1 and 2 includes a liquid crystal indicating element or section 1 combined with membrane keying keyboard 3 to form a unitary structure. The liquid crystal indicating section 1 includes a glass or base plate 5 and a glass cover plate 7 which is fastened to the base plate and which forms the module's view field. The base plate 5 and the cover plate 7 carry electrodes, not shown in detail, which establish the shape of the symbols 9 to be indicated and enclose the substance forming the liquid crystal between them. The base plate 5 projects laterally beyond each edge of the cover plate 7 and conductive paths or tracks 11 are vapor deposited on its surface facing the cover plate 7.The paths 11 extend into the area of the base plate 5 project beyond the plate 7 and there serve for connection of the unitary structure.

A number of surface-mounted contact segment pairs 15 of the keyboard 3 are vapor deposited onto the surface of the base plate 5 that faces the cover plate 7.

These segment pairs 15 appear in an area of the base plate 5 that projects laterally beyond the cover plate 7. The segment pairs 15 are connected with conductive paths 17 which serve as connections and are likewise vapor deposited. An elastic keying membrane 19 of silicone rubber or plastic overlaps the surface contact segment pairs 15. The keying membrane 19 forms switching domes 21 which is curved away from the contact segment pairs 15 above and around each segment pair. Inside each switching dome 21 the keying membrane 19 carries an electrically conducting surface-deposited counter-contact segment 23 which connects the two contact segments located beneath the latter with one another when a user presses a switching dome 21 downwardly.

The keying membrane 19 extends over the keyboard 3 as well as over the view field of the liquid crystal indicating section 1 formed by the cover plate 7. The membrane 19 is fastened and sealed, e.g. cemented, directly to the base plate 5 of the liquid crystal indicating element 1 along an area 25 peripherally enclosing the keyboard 3 as well as the cover plate 7 of the liquid crystal indicating section 1. Other cementing areas can be provided within the area 25. The contact paths 11 and 17 project over the border of the keying membrane 19 at at least one lateral edge of the base plate 5.

Fig. 3 shows a pocket calculator module in which not only contact segments 35 of a foil keyboard 37 but also chips 39 of a microprocessor and a solar cell 41 are directly attached to a carrier or base plate 31 of a liquid crystal indicator 33. The base plate 31 carries all the conductor paths necessary for the connection of the keyboard 37, the liquid crystal indicator 33, the microprocessor 39, and the solar cell 41. An elastic keying membrane 43 of silicone rubber or plastic covers the liquid crystal indicator 33, the keyboard 37, the microprocessor 39, and the solar cell 41. The keying membrane 43 includes switching domes 45 over the area of the keys in the keyboard 37 and is composed of transparent material at least in the area of the indicator 33 and the solar cell 41.The keying membrane 43 is tightly sealed to the base plate 31 of the liquid crystal indicator 33 at least in an area 47 peripherally enclosing the indicator 33, the solar cell 41, the microprocessor 39 and the keyboard 37. In one embodiment of the invention the base plate 31 is reinforced so that the pocket calculator module achieves enough stability to dispense with an additional housing. In one embodiment of the invention the solar cell 41 is dispensed with and connection lines for connecting a battery or the like extend out of the sealed module.

In the embodiments discussed the base plate is composed of glass as is conventional in liquid crystal indicators. Other materials, such as ceramics or the like are used in other embodiments. Metallic carrying plates, particularly aluminum or stainless steel, are used in still other embodiments, and their surfaces, which hold the conducting paths are provided with non-conducting coatings such as aluminum oxide or the like.

While the embodiments of the invention have been described in detail, it will be evident that the invention may be embodied otherwise without departing from the spirit and scope of the invention.

Claims

1. An optoelectric structural unit, comprising: a liquid crystal indicating element having a base plate with an insulating surface and a transparent cover plate forming a view field and covering a portion of the insulating surface of the base plate; said base plate and said cover plate sandwiching a liquid crystal between them; said base plate projecting laterally beyond the cover plate and forming a projecting area; a plurality of conductor paths on the insulating surface of said base plate between said base plate and said cover plate and extending into the projecting area; said conductor paths forming a surface contact on said projecting area of said base plate on the insulating surface;; an elastic membrane covering said surface contact and having a surface counter-contact on a surface facing said surface contact and opposing said surface contact so as to make a connection with said surface contact when the diaphragm is pressed against the base plate; and said membrane being sealed to said base plate in an area surrounding said surface contact.

2. A unit as in claim 1, wherein said membrane extends over and beyond said cover plate and is sealed to said base plate over plate between the membrane and said base plate, and wherein the portion of said membrane covering said cover plate is transparent.

3. A unit as in claim 2, wherein said cover plate includes peripheral edges and said base plate extends beyond the peripheral edges, and wherein said membrane is sealed to said base plate surrounding the edges of said cover plate.

4. A unit as in claim 1, further comprising an electronic element mounted on said base plate and connected to said paths, said membrane covering said electronic element and being sealed against the base plate so as to surround said element.

5. A unit as in claim 2, further comprising an electronic element mounted on said base plate and connected to said paths, said membrane covering said electronic element and being sealed against the base plate so as to surround said element.

6. A unit as in claim 3, further comprising an electronic element mounted on said base plate and connected to said paths, said membrane covering said electronic element and being sealed aginst the base plate so as to surround said element.

7. A unit as in claim 4, wherein said electronic element is a microprocessor chip.

8. A unit as in claim 5, wherein said electronic element is a microprocessor chip.

9. A unit as in claim 6, wherein said element is a microprocessor chip.

10. A unit as in claim 7, further comprising a solar cell mounted on said carrier plate, said membrane covering said solar cell and being sealed to said base plate to peripherally seal an area surrounding said solar cell, said solar cell being connected to said paths.

11. A unit as in claim 8, further comprising a solar cell mounted on said carrier plate, said membrane covering said solar cell and being sealed to said base plate to peripherally seal an area surrounding said solar cell, said solar cell being connected to said paths.

12. A unit as in claim 9, further comprising a solar cell mounted on said carrier plate.

said membrane covering said solar cell and being sealed to said base plate to peripherally seal an area surrounding said solar cell, said solar cell being connected to said paths.

13. An optoelectric structural unit as claimed in Claim 1, substantially as described herein with reference to and as illustrated by any one of the examples shown in the accompanying drawings.