Illumination – Illuminated scale or dial
Reexamination Certificate
1999-04-14
2001-04-17
O'Shea, Sandra (Department: 2875)
Illumination
Illuminated scale or dial
C362S026000, C362S086000, C362S035000, C362S085000, C362S029000
Reexamination Certificate
active
06217182
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an electronic device with a backlit display and an illuminated receptacle for a removable information storage medium, for example an audio device such as a cassette radio for a motor vehicle passenger compartment.
Electronic devices often have a combination of a backlit display, such as a liquid crystal display, and a receptacle for a removable information storage medium, such as an audio cassette. In many situations, for example in a motor vehicle passenger compartment, it may be difficult for a user readily to locate the entrance to the receptacle, particularly if this is covered over with a flap or door prior to insertion of the information carrier. One known way of indicating the location of the doorway is to provide a light source, for example a light emitting diode (LED), in close proximity with the entrance, so that light from the LED illuminates a part of the entrance so that it can more easily be located. In one conventional arrangement, the LED abuts a transparent light pipe that runs along the length of a doorway.
As regards the display, in one arrangement known from a motor vehicle cassette radio, a display is held on a display carrier on which LEDs are mounted for backlighting the display. A transmissive diffuser, such as frosted clear plastic material, is sometimes provided so that the light is more evenly distributed across the display.
The display LEDs may be mounted on a printed circuit board, on which the display and optionally a diffuser may be clipped or otherwise held. The same circuit board may hold another LED used to feed light into the light pipe to illuminate the entrance to the receptacle.
Whilst such arrangements are effective in providing the desired optical effects, two separate optical components must be provided; one for the display backlight and one of the entrance illumination. Therefore, it is generally necessary for a number of components such as a display carrier, optical light pipes or diffusers, and one or more PCBs to be fixed in place, usually by means of screws to the inner surface of a display or instrument bezel, which may then in turn be clipped to a chassis of the electronic device. This number of separate items and manufacturing steps adds to the cost of the audio device.
Furthermore, in order to benefit from the use of a single PCB, it is necessary for these components to be held in alignment with each other and the display and receptacle entrance. Particularly with moulded plastics components, this places tight tolerances on components' dimensions, which again adds to manufacturing cost.
It would be desireable to provide a more convenient arrangement for an electronic device having a backlit display and illuminated receptacle for a removable information storage medium.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an electronic device having a backlit display and a receptacle for a removable information carrying medium, comprising at least one backlight, and a light diffuser moulded in a translucent plastics material, characterized in that the diffuser has a display backlight portion and a receptacle indicator portion, said backlight being arranged to illuminate the display backlight portion to provide a diffuse backlight for the display, and to shine light through the translucent material of the receptacle indicator portion to indicate an entrance to the receptacle.
The term information storage medium as used herein applies in its widest sense to any analogue or digital data carrier, such as a disc, tape, card, whether pre-recorded, recordable, erasable or permanent, and whether or not including a cartridge or cassette.
The display may be a liquid crystal display, backlit with a convenient backlight such as an array of light emitting diodes (LEDs).
The translucent material may be white, in which case the colour of the backlight illumination is determined just by the color of the backlight source. It would, however, be possible for the translucent material to have a different colour, particularly if the backlight was non-monochromatic.
The diffuser could be made from two or more components, for example one for the display portion and one for the indicator portion, but preferably the diffuser is of unitary construction, for example being integrally moulded in a plastics material.
Usually, the entrance will be elongate, as would be the case for a compact audio cassette, or a compact disc. The indicator portion may then most conveniently extend along substantially the full length of the entrance, so that the user can more readily insert or retrieve the storage medium into or from the receptacle. It is not necessary however, for the illumination indicating the location of the receptacle to be so bright that the entrance is fully illuminated. It is sufficient only that the illumination is bright enough to indicate the location of the receptacle when this would otherwise be difficult to see, for example as would be the case in a dimly lit motor vehicle passenger compartment at night.
In a preferred embodiment of the invention, the indicator portion terminates in an indicator strip that runs along the length of the entrance. Since the user in most cases will normally be looking somewhat down on the electronic device, this strip may be along a lower edge or side of the entrance.
Often, the receptacle will have a door at the entrance, and the indicator strip may then be aligned with the door so it is at least partially visible at the edge of the door.
The invention is most useful when the display is in proximity with the receptacle, by which it is meant that the receptacle is no farther, or little farther, from the at least one backlight than the farthest part of the backlit display illuminated by the same backlight. The same backlight may then efficiently be used to illuminate both the display and indicator portions, without the need for intervening optical elements, such as lenses, fibre optics, or light pipes. In a preferred embodiment, said backlight is disposed between the display portion and indicator portion.
One way in which the indicator portion may be formed is in the shape of a hollow shell of the translucent material. The shell then has a cusp at the entrance to the receptacle, said backlight being arranged to illuminate the inside of the shell so that light is transmitted through the translucent material of the cusp of the shell to indicate the entrance to the receptacle.
The display may be backlit in various ways. One way is if the diffuse back illumination for the display is provided by light transmitted through the translucent material of the display backlight portion. Another way is if the diffuse back illumination of the display is provided by light incident upon and scattered away from the translucent material of the display portion. Most of the scattered light will be from the surface of the translucent material although some would be back scattered from the bulk of the material near surface.
Such surface scattering provides a relatively efficient means of spreading the light from the light source, with minimum absorption and stray reflection by the translucent material, particularly if the light upon a backlight surface of the display portion is at a shallow angle over substantially most or all the area. The term shallow angle is used herein to refer to an angle within 45° of the surface at a point on the backlight surface, and preferably less than about 30°. The efficiency of illumination becomes more important for larger area displays owing to the need otherwise to employ a large number of light sources to provide sufficient illumination.
Therefore, at least one backlight of the display portion may be disposed to one side of the display portion, and illuminates the backlight surface of the display portion at a shallow angle. Preferably the display portion has a linear array of backlights disposed along an edge of the display portion, the backlight surface of the display portion being concave in
Garnham Adrian
Shepherd Mark Robert
Ford Global Technologies Inc.
Hobden David V.
Kajander John
O'Shea Sandra
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