GB2190529A

GB2190529A - Improvements relating to liquid crystal displays

Info

Publication number: GB2190529A
Application number: GB08710950A
Authority: GB
Inventors: David Viewing; Andrew Faulkner
Original assignee: Husky Computer Ltd
Current assignee: Husky Computer Ltd
Priority date: 1986-05-16
Filing date: 1987-05-08
Publication date: 1987-11-18
Also published as: GB8710950D0; GB8611998D0; GB2190529B

Abstract

An item of electronic equipment such as a portable microcomputer has a liquid crystal display (36) mounted on a printed circuit board (44) which is directly secured to a housing (30) of the micro computer. The liquid crystal display is mounted behind an opening (32) the edges of which serve as a bezel for the liquid crystal display. A resilient 52 gasket (54) extends around the periphery of the liquid crystal display and is sandwiched between the display and the bezel to prevent movement of the latter relative to the housing.The mounting of the liquid crystal display directly to the housing ensures that only minimal flexing stresses can be applied to the liquid crystal display and the gasket cushions acceleration forces generated by impact shocks, enabling the liquid crystal display to withstand considerable impact shocks applied to the micro computer housing. An electroluminescent panel may be provided for backlighting. <IMAGE>

Description

SPECIFICATION Improvements in and relating to liquid crystal displays The present invention relates to liquid crystal displays A liquid crystal display (LCD) is a type of passive display which uses a liquid crystal whose reflectivity can be altered by applying an electric field across the liquid crystal. Such LCD's have extremely low power consumption and can easily be fabricated to provide relatively complex displays, as a result ofwhich they are increasingly being used in, for example, pocket calculators and portable micro computers.

Unfortunately, a major disadvantage of LCD's is theirsusceptibilityto impact damage. The con- ventional LCD is constructed as a self-contained component in which the liquid crystal is sealed between two parallel, thin glass plates, the electric field being applied across the crystal through a conductive coating on at least one of the glass plates.

In a conventional assembly, the LCD component is incorporated into a complete circuit module which utilises a printed circuit board (pcb) to carry elec tronicdriven components and a simple metal bead to hold the LCD to the pcb (Figure 1).

When mounted in, for example, a computer how ever thins construction provides little or no resistance to impact or deflection forces applied to the computer. For example, if the computer is dropped or receives a severe knock, a frequent result is thatthe glass plates crack rendering the LCD module useless.

The present invention seeks to provide an improved liquid crystal display.

The present invention provides an item of electronic equipment having a housing and a liquid crystal display connected to a printed circuit board, wherein a portion of said housing serves as a bezel means for said liquid crystal display, and said printed circuit board is secured to said housing to retain said liquid crystal display securely between said circuit board and said bezel means.

Mounting the LCD directly into the housing e7l- sures that the LCD is securely held and is protected from impact shocks by the relatively rigid housing.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure lisa sectional elevation of a hitherto known construction of LCD module; Figure2 is a diagrammatic sectional elevation of an assembly according to the present invention of an LCD mounted in a portable micro computer; Figure 3 is a side elevation, partly in section along the line3 - 3 of Figure 4, showing a practical form of the assembly of Figure 2; and Figure 4 is a plan view of the assembly of Figure 3.

In the drawings like parts have like reference numbers.

Referring firstly to Figure 1,this showsthe construction of a conventional LCD module 10. The liquid crystal display comprises a liquid crystal 14 sealed between two parallel plates 16,18 ofglass.

The LCD is held in position by a metal bezel 20 secured to a printed circuit board 22 (pcb). The PCB 22 carries a drive circuit (not shown in the drawings) for the LCD and is electrically coupled to the LCD through a conductive elastomer 24.

The above-described construction of LCD module has the inherent disadvantage that any deflection force applied to the module is transmitted directlyto the glass plates. The metal bezel, for example, is re lativelyflexible and would not be able to resist deflection forces applied to it as a result of the equipment in which the module is mounted being subjected to impact shocks. The bezel would instead transmittheseforcestothe glass plates.

Any flexing ofthe pcbwould also cause flexing of the bezel with the same results. In addition, there is a danger ofthe LCD vibrating in the module and "colliding" with the metal bezel, causing chipping and possible failure ofthe LCD.

Figures 2 to 4 show a preferred construction of LCD module according to the present invention. In con- trash with the known LCD module, the LCD shown in Figures 2 to 4 is not constructed in a self-contained module but is mounted directly in the housing of the apparatus, such as a portable micro computer, in which the LCD isto be used.

Figure 2 shows a portion of a portable microcom- puter housing 30 made of a material which is sufficiently rigid for the purpose of the present invention.

The housing may conveniently be machined from aluminium although any other suitable material can be used.The housing has an opening 32through which the LCD can be viewed and which is sealed by a protective window 34, preferably of plastics material such as acrylic resin.

The LCD 36 has a liquid crystal 38 sealed between two parallel glass plates 40,42 in the normal manner.

However, the LCD is supported on a printed circuit board 44 which is directly secured to the housing 30 at 46 and 48 by suitable means, such as, for example, screws. Electricai connection between the PCB and the LCD is made, as usual, through conductive elastomers 50,52. The LCD itself is spaced from the surrounding housing 30 by a resilient gasket 54 which is made of any suitable material such as rubber or synthetic rubber. The gasket is preferably a moulded, one-piece gasket extending the full periphery of the LCD and moulded to the required cross sectional contour in order to provide a firm fit between the housing 30 and the LCD 36 and prevent movement of the LCD relative to the housing.

Figures3and4showa practical form ofthe assembly of Figure 2. An electroluminescent panel 60 is provided as a backing to the LCD in orderto improve viewing ofthe LCD.

The mounting of the LCD directlytothe metal housing ensures thatthere can be only minimal flexing stresses applied to the LCD. Because the housing is cast or machined metal it does not deflect significantly when subject to impact shocks, even, for example, when dropped on to a concrete floor. The moulded gasket 54 cushions acceleration forces generated by impact shocks and distributes loading forces evenly. The gasket may conveniently be held in position by adhesive.

The construction also prevents the LCD moving re native to the housing so that it cannot collidewith other parts of the apparatus.

The elimination of the surrounding bezel provides a considerableweightsaving and the increased strength of the construction enables the LCD to withstand extreme physical liable to be encountered when used in an outdoor environment.

Claims

1. An item of electronic equipment having a housing and a liquid crystal display connected to a printed circuit board, wherein a portion of said housing serves as a bezel meansforsaid liquid crystal display, and said printed circuit board is secured to said housing to retain said liquid crystal display securely between said circuit board and said bezel means.

2. An item as claimed in claim 1 further comprising resilient means between said liquid crystal display and said bezel for reducing the transmission of shockwaves between said bezel and said liquid crystal display.

3. An item as claimed in claim 2 wherein said resilient means extends substantially the full periphery of said liquid crystal display.

4. An item as claimed in claim 2 or 3 wherein said resilient means is a gasket.

5. An item of electronic equipment having a housing and a liquid crystal display, substantially as herein before described with reference to Figures 2 to 4 of the accompanying drawings.

6. An item as claimed in any of claims 1 to 5 wherein said item is a portable micro computer.