IES20010199A2 - Moulded plastics lens - Google Patents

Abstract

A process for manufacturing a plastics lens includes moulding a lens in a moulding machine (20) with a hardened lacquer layer being fused to a front face of the lens in the mould (20). The lens is removed from the mould (20) and delivered to a cleaning compartment (33). At the cleaning compartment (33), the lens is mounted on a carriage (34), which is advanced into the cleaning compartment (33). Within the cleaning compartment (33), a pressurised air stream is directed at the lens for blowing away flaked waste lacquer material from the lens. A vacuum is applied to an interior of the cleaning compartment (33) for forced extraction of flaked waste material. The carriage (34) leaves the cleaning compartment (33) and the lens is delivered to a printing station (60) at which one or more flexible pads (62) apply ink to the lens surface to decorate and/or print indicia on the lens in a desired design. <Figure 4>

Description

This invention relates to a moulded plastics lens and to a process for manufacturing these lenses.

The invention is particularly concerned vwth the manufacture of lenses for electronic devices such as mobile phones, such lenses being mounted over and protecting alpha numeric displays on these devices. The manufacture includes the printing of indicia on a surface of the lenses by means of a “tampo” or “tampon printing method.

Statements of Invention According to the invention, there is provided a process for manufacturing a moulded plastics lens including the steps.- moulding a transparent plastic lens having a hardened scratch-resistant front face by leading a carrier film coated on one face with a layer of hardened polycarbonate lacquer between a complementary pair of mould parts, moving the mould parts together to define a shaped mould cavity therebetween, injecting molten polycarbonate material into the mould cavity on the coated side of the film to form a shaped lens within the mould cavity, fusing the hardened lacquer layer to a front face of the lens, opening the mould and removing the lens, at a printing station, mounting the cleaned lens face down in a desired cleaning the lens to remove loose flakes of lacquer material from an external surface of the lens, - 2 IE010199 orientation in a holder, delivering the holder through a charged atmosphere which neutralises static attraction of particles to the lens, blowing air over the uppermost surface of the lens to remove static particles from the lens after the static charge attraction has been neutralised, printing an ink decoration onto the uppermost surface of the lens by means of a flexible pad, and removing the printed lens from the holder.

In one embodiment of the invention, the cleaning is carried out by mounting the lens on a carriage, advancing the carriage into a cleaning chamber, directing a pressurised airstream at the lens within the cleaning chamber for blowing away flaked material from the lens, and retracting the carriage out of the cleaning chamber.

Preferably, the process includes the step of applying a vacuum to an interior of the cleaning chamber for forced extraction of flaked waste material. in a further embodiment, the process includes the step of generating the charged atmosphere by means of a deioniser which directs a stream of charged ions towards the lens in the holder.

In another embodiment, the printing on the lens is carried out in two stages by printing indicia in a first ink colour on the uppermost face of the lens and subsequently overprinting said indicia in a second contrasting ink colour forming a background field about the indicia. - 3 IE010199 In another embodiment, the process includes the step of directing a heated airstream at an inked surface of the lens after printing for forced drying of the ink on the lens.

In a further embodiment, the process includes the step of partially drying the ink on the pad before applying the ink to the lens.

In a further embodiment, the process includes the step of applying a sealing grommet to a rear face of the lens after printing.

Preferably, the process also includes the step of applying peel-away protective cover sheets to a front face and to a rear face of the lens after printing.

Detailed Description of the Invention The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:Fig. 1 is an elevational view of a moulded plastic lens according to the invention; Fig. 2 is a rear elevational view of the lens; Fig. 3 is a side elevational view of the lens; Fig. 4 is a perspective view of lens manufacturing apparatus according to the invention; and Fig. 5 is a schematic illustration of a deioniser forming portion of the lens manufacturing apparatus.

Referring to the drawings, and initially to Figs. 1 to 3 thereof, there is shown a moulded plastics lens according to the invention, indicated generally by the reference numeral - 4 IE010199 1. The lens 1 has a body 2 of polycarbonate material having a scratch-resistant outer or front face 3 formed by a thin layer of hardened polycarbonate material. A rear face 4 of the lens 1 carries a printed design thereon which typically comprises lettering 5 and/or a logo 6 or the like in a first ink colour which is overprinted by a border 7 in a contrasting ink colour which also defines a central transparent window 8 portion of the lens 1. An endless sealing grommet 10 is adhesively secured to the rear face 4, extending around a peripheral portion of the lens body 2. The grommet 10 has an adhesive coated outer surface. Lugs 12 project outwardly of a bottom edge of the body 2 for location with complementary slots in a cover of a mobile phone.

Preferably, a peel-away protective cover sheet is mounted across the front face 3 of the body 2 and a backing strip is mounted over the rear face 4 of the body 2 to protect the exposed adhesive covered face of the grommet 10 prior to mounting the lens 1 in the mobile phone cover.

Referring in particular to Fig. 4, a process and apparatus for manufacturing the lens 1 will be described. A moulding machine 20 has a complementary pair of mould parts, namely, a fixed mould part 21 and a movable mould part 22 which is movable towards and away from the fixed mould part 21. The mould parts, when engaged together, define a shaped mould cavity therebetween for moulding the lens body 2. The mould cavity is shaped to simultaneously mould four such lens bodies 2 interconnected by an l-shaped frame. A carrier film 24 passes between the mould parts 21, 22 in alignment with the mould cavity, being spooled between a supply reel 25 and a waste take-up reel (not shown). The carrier film is coated on one face with a layer of hardened polycarbonate lacquer. To mould each set of four lenses, the mould parts 21, 22 are engaged clamping the carrier film 24 therebetween. Liquid polycarbonate material is then injected into the mould cavity on the lacquered side of the carrier film 24, the hardened polycarbonate lacquer being transferred from the earner film 24 and fusing to a front face of each lens 2 to form a thin scratch resistant hardened outer layer on a front face 3 of each lens body 2.

A robot arm 28 is slidably mounted on a longitudinal beam 29 which in turn is slidably mounted on a transverse beam 30. When the mould parts 21 separate after a moulding cycle, the robot arm 28 positions itself between the open mould parts 21, 22 - 5IE010199 and engages each of the four lens bodies 2 by means of associated suction pads on a vertical side face of the robot arm 28 at a lower end of the robot arm 28. The robot arm 28 then delivers the lens set to a cleaning station 32. At the same time, the carrier film 24 is incrementally advanced through the mould and the moulding cycle is then repeated.

The cleaning station 32 comprises a cleaning chamber or compartment 33 having an opening in one side face through which a lens carriage 34 is slidably movable on rails 35. A ram 36 is operable to advance the carriage 34 through the opening into the cleaning compartment 33 and retract the carriage 34 from the cleaning compartment 33. Immediately above the inlet to the cleaning compartment 33 is a pressurised air jet manifold 38 which is operable to direct a stream of pressurised air downwardly towards the carriage 34 when a carriage 34 locates within the cleaning compartment 33. A base of the cleaning compartment 33 has an outlet 39 which is connected to a vacuum source for extraction of waste materials from the cleaning compartment 33.

A loading arm 40 is pivotally mounted on a support 41 for receiving a lens set from the robot arm 28 and loading the lens set onto the carriage 34. The robot arm 28 moves from the mould to the loading arm 40 and transfers the lens set to the loading arm 40 which has a set of four suckers which engage a rear face 4 of each lens body 2. The robot arm 28 then moves over the carnage 34 and extends downwardly to pick up a cleaned lens set from the carriage 34, by means of suckers on a bottom face of the robot arm 28 engaging each lens body 2, lifting the cleaned lens set away from the carriage 34 for delivery to a cutting station 45.

When the robot arm 28 has lifted away from the carriage 34, the loading arm 40 pivots downwardly placing the newly moulded lens set on the carriage 34. The ram 36 then operates to advance the carriage 34 into the cleaning compartment 33. The pressurised air from the manifold 38 blasts downwardly blowing away any flaky material still attached to the lens set The carriage 34 is then retracted out of the cleaning compartment 33 by means of the ram 36 to await the return of the robot arm 28 on the next cycle.

At the cutting station 45, the lens set is mounted on a slide block 46 by the robot arm IE010199 - 6 28 which then returns to the mould to collect the next set of moulded lenses. The slide block 46 slides into a housing 47 within which is mounted a laser cutter which separates each lens body 2 from the l-shaped frame. The slide block 46 then slides back out of the housing 47.

A second robot arm 50 then moves over the slide block 46, engages the l-shaped frame and lifts the frame away from the slide block 46 and drops the frame into a waste collecting bin. The second robot arm 50 again moves over the slide block 46 and by means of suckers, picks up two of the lens bodies 2 from the slide block 46 and places them on a holder 52 mounted on a printing carousel 54. This printing carousel 54 then rotates to position a second holder 52 for reception of the remaining two lens bodies 2 which the second robot arm 50 collects from the slide block 46.

Each holder 52 is incrementally advanced on the carousel 54 to a decontamination station having a deioniser which is directed downwardly towards the top of each holder 52 positioned beneath the deioniser. The deioniser generates a charged environment of positive and negative ions which neutralise any charged particles on the rear face 4 of each tens body 2 which is to be printed upon. The ions generated by the deioniser neutralise the static charge of the lens body 2 generated during the moulding process. The deioniser also includes means for blowing an airstream across the uppermost surface of the lens bodies 2 in the holder 52 to blow away the particles which have been neutralised by the deioniser.

The deioniser is illustrated schematically in Fig. 5. Air is delivered from an air supply through an inlet pipe 70 through a filter 71 which removes impurities from the air and also removes moisture from the air. The purified air is then delivered through a manifold 72 having an outlet distributor 73 with a plurality of downwardly directed openings 74 for directing an air stream downwardly towards a lens body 2 in a holder 52 on the carousel 54 as it passes beneath the deioniser. A deioniser head 76 is supplied with power for cables 77. The deioniser head 76 generates a charged environment about its tip 78 which is directed downwardly towards the carousel 54, the resulting positive and negative ions acting on the lens body 2 and any particles adhered to the lens body 2 by static electricity to neutralise them. Subsequently, air discharged from the distributor 73 is blown across the top printing surface (rear face 4) - 7 IE010199 of the lens body 2 to blow away any neutralised particles leaving a clean surface for printing on the lens body 2. The deioniser components are housed within an outer casing 79.

The holder 52 then travels to a printing station 60. At the printing station 60, a number of flexible printing pads 62 are mounted on a rotatable star-shaped support 63. Each printing pad 62 is vertically movable on the support 63 so that the pad 62 can pick up an ink design and then move over the holder 52 and engage the uppermost surface of each lens body 2 to transfer the ink design to the lens body 2.

As the pad 62 swings over the carousel 54, a hot air blower partially dries the ink on the pad 62 immediately before printing. Conveniently, the printing may be done in two steps. In the first step, a first coloured ink with the writing and/or logo is applied to the dear lens body 2. Then the lens body 2 is overprinted with a second contrasting coloured ink defining the border 7. It will be noted that the first ink has a thicker consistency and a lower solvent content so that it will dry relatively quickly and will not run into the second ink forming the border 7.

A hot air blower is directed at the top surface of the lens bodies 2 immediately downstream of the printing station to facilitate rapid drying of the ink. The carousel 54 rotates through another increment and a discharge robot arm 65 picks up the lenses from the holder 52 and deposits the lenses 1 on a discharge conveyor 66. A hot air blower 68 adjacent an inlet end of the conveyor 66 directs hot air downwardly to ensure the ink is fully dry.

The printed lenses 1 then have the grommet 10 applied to the rear face 4 of each lens 1 and protective cover sheets are applied to the front and rear faces of the lenses 1 prior to packaging the lenses 1.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail within the scope of the appended claims.

Claims (5)

1. A process for manufacturing a moulded plastic lens including the steps:moulding a transparent plastic lens having a hardened scratch-resistant front face by leading a carrier film coated on one face with a layer of hardened polycarbonate lacquer between a complementary pair of mould parts, moving the mould parts together to define a shaped mould cavity therebetween, injecting molten polycarbonate material into the mould cavity on the coated side of the film to form a shaped lens within the mould cavity, fusing the hardened lacquer layer to a front face of the lens, opening the mould and removing the lens, cleaning the lens to remove loose flakes of lacquer material from an external surface ofthe lens, at a printing station, mounting the cleaned lens face down in a desired orientation in a holder, delivering the holder through a charged atmosphere which neutralises static attraction of particles to the lens, blowing air over the uppermost surface of the lens to remove static particles from the lens after the static charge attraction has been neutralised, printing an ink decoration onto the uppermost surface of the lens by means of a flexible pad, and - 9 IE010199 removing the printed lens from the holder.

2. A process as claimed in claim 1, wherein the cleaning is earned out by mounting the lens on a carriage, advancing the carnage into a cleaning chamber, directing a pressurised airstream at the lens within the cleaning chamber for blowing away flaked material from the lens, and retracting the carriage out of the cleaning chamber, and preferably the process includes the step of applying a vacuum to an interior of the cleaning chamber for forced extraction of flaked waste material.

3. A process as claimed in any preceding claim, in which the printing on the lens is carried out in two stages by printing indicia in a first ink colour on the uppermost face of the lens and subsequently overprinting said indicia in a second contrasting ink colour forming a background field about the indicia, and preferably the process includes the step of directing a heated airstream at an inked surface of the lens after printing for forced drying of the ink on the lens, and preferably the process includes the step of partially drying the ink on the pad before applying the ink to the lens.

4. A process for manufacturing a moulded plastics lens substantially as hereinbefore described with reference to the accompanying drawings.

5. A moulded plastic lens whenever produced by the process as claimed in any preceding claim.