Card – picture – or sign exhibiting – Changing exhibitor – Alphanumeric device
Reexamination Certificate
2001-05-23
2003-07-08
Morano, S. Joseph (Department: 3617)
Card, picture, or sign exhibiting
Changing exhibitor
Alphanumeric device
C040S452000, C040S448000
Reexamination Certificate
active
06588132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a light-emitting display device for displaying a numeral or character in seven segments or in a dot matrix structure using light emitting elements such as LEDs, which is used for displaying an amount of money in a vending machine. More specifically, this invention relates to a light emitting display device having a simple structure which includes a lead frame or resin circuit board and a reflecting case and is difficult to produce diffraction of light due to peeling of the coating of the display surface of the reflecting case or light leakage from its rear face. Further, this invention relates to a light emitting display device whose vertical direction can be easily known when it is attached to a circuit board, thereby facilitating its mounting, and can prevent leak of light from between display devices arranged in plurality.
2. Description of the Related Art
A conventional light-emitting display device having a seven-segment structure has structured as shown in FIG.
7
. In this structure, a light conducting portion constituting seven segments is formed in a reflecting case. For each segment, a light-emitting element (hereinafter referred to as “LED”) not shown is die-bonded or wire-bonded onto a lead frame or resin circuit board. The light conducting portion is filled with light-permeable resin
4
. The LED has an anode and cathode and hence must have two lead wires for each segment. In this case, the one lead wire for the anode or cathode may be common to the respective segments. Therefore, 8-10 lead wires (inclusive of that for a decimal point) are formed to exhibit a numeral of one digit. Namely, a plurality of lead wires
1
are provided along two long sides in a longitudinal direction (both sides in a display direction) or both upper and lower sides.
In order that the light emitted from the LED illuminates more brightly over the entire segment, the interior of the light conducting portion must be colored in whitish light-reflective color. Therefore, the reflecting case is generally made of whitish resin. Further, where the display surface is not a dark color such as black, the display color of each segment is difficult to recognize. For this reason, the surface of the reflecting case, as the case may be, the side thereof also is coated in the dark color such as black. The black coating is generally made in such a manner of drying black ink printed by screen printing.
As described above, in the light emitting display device for a numeral, its reflecting case is made of a whitish mold and the display surface is coated with a dark color such as black. However, the coating strength in the coating on the resin surface is not constant owing to the dirt of the surface state or reduction in flatness such as a projection due to a molding die. Therefore, the friction for the surface during transfer or contact therewith by handling during mounting is likely to produce scratching. Such a scratch leads to peeling of the black coating, exposes the underlying whitish resin and greatly deteriorates the appearance of the display surface.
Further, where the display is made on the arrangement of a number of units, not only the display surface but also the side surface is preferably coated with black because white on the side surface is difficult to see. However, the coating of the side surface causes the front and side surface rectangular prism to be coated by screen printing. In this case, the coating must be done for each surface. This greatly increases the number of man-hours of coating and the production cost. In addition, the problem of coating peeling still remains. Further, on the side of the bottom surface of the reflecting case, the case portion of the outer periphery and bottom surface to which a lead frame or resin circuit board portion is attached have different heights so that the entire bottom surface is not flat but complicatedly rugged. Therefore, it is very difficult to coat the bottom surface. The light which leaks toward the bottom via filled resin repeats random reflection between the whitish case of the bottom and the whitish lead frame plated with silver or resin circuit board having a metallic pattern so that light leakage occurs outside of another segment or the reflecting case. This is likely to produce erroneous exhibition. Where the reflecting case is formed of whitish resin, revived resin cannot be used since it cannot give white with high reflection coefficient. Namely, resources cannot be efficiently used.
Further, the light emitting display device for displaying numerals has the same appearance even when it is turned upside down where it has no decimal point. However, the lead connection is not necessarily symmetrical. Therefore, with its direction known correctly, the device must be mounted. In this case, since the appearance is entirely symmetrical, it is very difficult to know its direction.
In the light emitting display device such as a numeral display, a few of device units are arranged side by side to exhibit many digits. In this case, the device units must be arranged with no gap. However, for permission of the clearance during the process for manufacturing the device, and during its mounting, the gap of at least 0.1 mm or more must be given between the device units. Therefore, the gap between the adjacent device units cannot be removed completely. Meanwhile, in the light emitting display device with a reflecting case inclusive of its bottom coated with resin, the light emitted from the LED leaks to the bottom side of the reflecting case via the resin and the leaked light further leaks from the gap between the light-emitting display device units so that erroneous recognition of apparently exhibiting “1” between numerals occurs.
Further, in this kind of light emitting display device, its surface exclusive of e.g. segments of a numeral is colored in black to provide the good appearance. However, the light conducting portion in the vicinity of the LEDs is preferably colored in white to prevent absorption of light, thereby improving the display luminance. For this reason, the reflecting case is generally formed of whitish plastic and the surface of the display screen and its side surface as necessary are coated with black. On the other hand, where this light emitting display device is transferred, several tens of device units housed in a tube (stick) of plastic are transferred. In this case, at the time of taking in and out or where there is an internal clearance, the display screens of the device units are rubbed in the tube during the transfer. As a result, the coating may be peeled so that the display quality will be deteriorated.
SUMMARY OF THE INVENTION
This invention has been accomplished in order to solve the problem described above. An object of this invention is to provide a light-emitting display device which can reduce light leakage by coloring the reflecting case inclusive of the bottom in a light-absorbable color, thereby preventing erroneous exhibition.
Another object of this invention is to provide a light-emitting display device having a structure in which white is not exposed even when slight scratch is produced on the display surface so that the display surface is not spotted.
Still another object of this invention is to provide a light emitting display device having a structure in which revived resin can be used for the reflecting case.
Further, this invention has been accomplished in order to solve the above problem. An object of this invention is to provide a light emitting device whose vertical direction can be easily known.
Still yet another object of this invention is to provide a light emitting display device in which erroneous recognition of exhibition due to the leakage of light from gaps between a number of device units does not occur.
Still further object of this invention is to provide a light emitting display device in which the coating on the display screen owing to rubbing is not peeled and the display quality is not deteriorated.
Further yet
Bellinger Jason R.
Morano S. Joseph
Morgan & Lewis & Bockius, LLP
Rohm & Co., Ltd.
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