Ultraviolet and bright visible light emanating from the arc developed in a welding operation are hazardous to unshielded eyes of persons viewing the welding operation. Such light even when viewed from a distance can burn and possibly permanently damage the viewer's eyes. For these reasons, among others, including the desire to completely enclose a workman with his/her welding projet, welding safety screens (or curtains) have been widely used.

Some conventional welding safety screens comprise opaque curtains surrounding the welding work area for completely blocking visible and ultraviolet light emanating from the arc. A disadvantage associated with such welding screens is they prevent persons outside the screen from viewing the welding work area. Other conventional welding safety screens comprise panels which are transparent to visible light and absorb ultraviolet light. Although these screens enable others to view the welding work area without damage caused by ultraviolet light, they do not block the harmful effects of the intense visible light from the arc.

Liquid crystal shutters have been used in welding helmets to block the harmful effects of visible and ultraviolet light generated by a welding arc. Such liquid shutters are operable between a lightened state and a darkened state. In the lightened state, transmissivity of light through the shutter is high. In the darkened state, transmissivity of light through the shutter is low. Such shutters

generally have an optical detector which generates a signal in response to light emanating from the arc to change the shutter from its lightened state to its darkened state. Although effective for welding helmets, such liquid crystal shutters are too small t be used for safety screens.

Summary of the Invention Among the several features and avantages of the present invention may be noted the provision of improved apparats and method for protecting eyes from the harmful effects of intense visible and ultraviolet light; the provision of such an apparats and method which enables a viewer to view a welding work area while protecting such viewer from the harmful effects of intense visible and ultraviolet light generated by a welding arc; and the provision of such apparats which is of relatively simple construction.

In general, a welding protection apparats of the present invention provides eye protection from ultraviolet light and visible light generated by a welding apparats during a welding procedure. The apparats comprises an eye protection panel configure to absorb ultraviolet light in a manner to prevent the ultraviolet light generated during the welding procedure from injuring eyes of a user viewing the welding procedure through the panel. Further, the panel is switchable between a light scattering state and a transparent state. When in its light scattering state, the panel diffuses visible light in a manner to prevent harmful visible light (e. g. blue light) generated during the welding procedure from injuring the eyes of the user viewing the welding procedure through the panel.

When in its transparent state, the panel permits the passage of visible light in a manner to facilitate a clear view of the welding apparats by the user. Preferably, the panel is in its light scattering state during generation of intense visible light from the welding procedure, and is in its transparent state during periods when the welding apparats is not generating intense visible light.

In another aspect of the present invention, a welding protection apparats of the present invention comprises a liquid crystal device and a shield

layer. The liquid crystal device is switchable between a light scattering state and a transparent state. The liquid crystal device when in its light scattering state diffuses visible light in a manner to prevent the visible light generated during the welding procedure from injuring the eyes of the user viewing the welding procedure through the liquid crystal device. The liquid crystal device when in its transparent state permits the passage of visible light in a manner to facilitate a clear view of the welding apparats by the user when the user is viewing the welding apparats through the liquid crystal device during periods when the welding apparats is not generating visible light. The shield layer is preferably superimposed with the liquid crystal device. The shield layer is adapted to absorb ultraviolet light in a manner to prevent the ultraviolet light generated during the welding procedure from injuring eyes of a user viewing the welding procedure through shield layer.

A method in accordance with the present invention is for protecting eyes of a person from ultraviolet light and visible light generated by a welding apparats during a welding procedure. The method comprises providing an eye protection panel between the welding apparats and the person. The eye protection panel is switchable between a light scattering state and a transparent state. The panel when in its light scattering state diffuses visible light in a manner to prevent the visible light generated during the welding procedure from injuring the eyes of the user viewing the welding procedure through the panel. The panel when in its transparent state permits the passage of visible light in a manner to facilitate a clear view of the welding apparats by the user when the user is viewing the welding apparats through the panel during periods when the welding apparats is not generating visible light. The method further comprises switching the eye protection panel to its light scattering state when the welding apparats is generating visible iight.

Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief Description of the Drainas Fig. 1 is a perspective view of a welding safety screen of the present invention having a plurality of eye protection panels surrounding a welding operation; Fig. 2 is a cross-sectional view taken along the plane of line 2-2 of Fig. 1 showing the various layers of an eye protection panel of the welding safety screen of Fig. 1; Fig. 3 is a cross-sectional view of a liquid crystal device of the eye protection panel of Fig. 2, the liquid crystal device being in a light scattering state so that visible light passing through the eye protection panel is diffuse; Fig. 4 is a cross-sectional view similar to Fig 3, but showing the liquid crystal device in a transparent state so that visible light passing through the eye protection panel is substantially not diffuse; and Fig. 5 is a schematic view of the eye protection panel connecte to a power source and a controller.

Detailed Description of the Preferred Embodiment Referring now to the drawings, and first more particularly to Fig. 1, a welding safety screen of the present invention is indicated in its entirety by the reference numeral 20. The welding safety screen 20 is configure for being positioned between a welding work area and a viewer (not shown) to protect the eyes of the viewer from ultraviolet light, infrared light, and intense visible light emanating from a welding arc generated during a welding operation. The welding safety screen 20 inclues at least one eye protection panel, generally indicated at 22. Preferably, the welding safety screen 20 inclues a plurality of eye protection panels 22 surrounding the welding work area.

Referring to Fig. 2, the eye protection panel 22 is of a layered construction comprising a liquid crystal device, generally indicated at 24, a transparent shield layer 26, and first and second transparent panes 28,30. As discussed in greater detail below, the liquid crystal device 24 is switchable between a light scattering

state and a transparent state for shielding a user from harmful effects of blinding visible light emanating from the arc of a weld. The shield layer 26 is adapted to shield ultraviolet and infrared light.

Preferably, the liquid crystal device 24 and shield layer 26 are positioned between the panes 28,30. The panes 28,30 are preferably of heat-strengthened glass. However, it is to be understood that the panes could be of other suitable transparent materials without departing from the scope of this invention. The eye protection panel 22 also preferably inclues first, second and third thin, transparent interlayers (not shown) of a polymeric material. The first interlayer is interpose between the first pane 28 and the liquid crystal device 24. The second interlayer is interpose between the liquid crystal device 24 and the shield layer 26. The third interlayer is interpose between the shield layer 26 and the second pane 30. The interlayers act as a bonding/heat-sealing agent to hold together the layers of the eye protection panel 22 and are commercially available from Techniver Saint-Roch of Belgium. The liquid crystal device 24, shield layer 26, panes 28,30, and interlayers are all superimposed with one another so that a viewer looking through the eye protection panel 22 looks through all layers.

As shown in Figs. 3 and 4, the liquid crystal device 24 preferably comprises a polymer disperse liquid crystal (PDLC) film 32 having first and second opposite faces covered with first and second transparent electrically conductive layers 34,36, and polyethylene terephthalate (PET) film layers 38 facing the electrically conductive layers. Preferably, the liquid crystal device 24 is of the type commercially available from Techniver Saint-Roch of Belgium used in the switchable window, sold under the trade designation PRIVA-LITEO. The conductive layers 34,36 are connecte to flat electrical bus bars (not shown) located on opposite edges of the panes 28,30. The bus bars connect the liquid crystal film 32 to a power supply.

The liquid crystal device 24 is switchable from a translucent (or light scattering) state represented by Fig. 3, and a transparent state represented by

Fig. 4. The liquid crystal device 24 is in its light scattering state when it is not subjected to any electrical current. In the light scattering state (Fig. 3), the liquid crystals encapsulated in the PDLC film 32 are randomly positioned and their disorderly position diffuses light in all directions to block vision through the eye protection panel 22. In its light scattering state (Fig. 4), the liquid crystal device 24 diffuses visible lights sufficiently to prevent the intense visible light emanating from a welding arc from injuring the eyes of a viewer viewing the welding procedure through the eye protection panel 22. When an electric current is applied across the conductive layers 34,36, the liquid crystals encapsulated in the PDLC film 32 align and reorient themselves to render the PDLC film transparent. In its transparent state, the liquid crystal device 24 is sufficiently transparent so as not to impede a clear view of welding apparats by the viewer when the viewer is viewing the welding apparats through the eye protection panel 22 during periods when the welding apparats is not generating a welding arc. Although in its transparent state the liquid crystal device 24 is transparent, it is not necessarily colorless. If constructed as specified herein, the liquid crystal device 24 has an orange or bronze tint.

Referring to Fig. 5, switching of the liquid crystal device 24 between its light scattering state and its transparent state is controlled by a suitable controller 40. The controller 40 is electrically coupled to a suitable light detector 42. The light detector 42 generates a welding signal responsive to operation of the welding apparats. The controller 40 switches the liquid crystal device 24 between its light scattering and transparent states in response to the generated welding signal. In particular, the controller 40 preferably switches the liquid crystal device 24 from its transparent state to its light scattering state by disconnecting the liquid crystal device from a power source 44 when the light detector 42 generates a welding signal representative of the welding apparats generating an arc. Likewise, the controller switches the liquid crystal device 24 from its light scattering state to its transparent state by connecting the liquid

crystal device from the power source 44 when the light detector 42 generates a welding signal representative of no arc emanating from the welding apparats.

Preferably, switching from the light scattering state to the transparent state or from the transparent state to the light scattering state is nearly instantaneous.

Although the preferred embodiment has been described as employing a light detector, it is to be understood that other means for signaling the controller can be used without departing from the scope of this invention. For example, the controller could be coupled directly to the welding apparats and be responsive to current or voltage generated by the welding apparats.

The transparent shield layer 26 preferably comprises a thin (e. g., 0.4 mm), transparent layer of PVC film. The shield layer 26 absorbs ultraviolet and infrared light to a sufficient degree so that ultraviolet and infrared light emanating from a welding arc will not injure the eyes of a viewer viewing the welding procedure through the eye protection panel 22. Preferably, the UV/IR shield layer 26 satisfis the standard EN 1598 for arc-welding application.

In operation, the welding safety screen 20 is positioned to enclose a welding work area so that the eye protection panels 22 separate a viewing area from the welding work area. Before operation of the welding apparats, power is supplie to the liquid crystal device 24 via the power source 44 to switch the liquid crystal device to its transparent state. In its transparent state, the liquid crystal device 24 is sufficiently transparent so as not to impede a clear view of welding apparats by the viewer when the viewer is viewing the welding apparats through the eye protection panel 22. During operation of the welding apparats, e. g., when the welding apparats is producing an arc, the light detector 42 generates a signal indicative of the welding apparats generating an arc. In response to such signal, the controller 40 switches the liquid crystal device 24 from its transparent state to its light scattering state by disconnecting the liquid crystal device from the power source 44. Because of the diffusion of light through the eye protection panel 22 when the liquid crystal device 24 is in its

light scattering state, a viewer in the viewing area watching the welding procedure is protected from the intense visible light by the liquid crystal device.

As the liquid crystal device 24 protects the viewer from the harmful effects of visible light, the transparent shield layer 26 protects the viewer from the harmful effects of ultraviolet and infrared light. When the welding operation is discontinued, the controller 40 switches the liquid crystal device 24 back to its transparent state. Thus, the eye protection panel 22 protects a viewer from the harmful effects of light generated during a welding procedure without the need for any additional eye protection, while allowing the viewer to inspect the welding operation during periods when the welding apparats is not producing intense visiblelight.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.