Vancraeynest, Jeroen c/o Holstlaan, Prof. 6. (AA Eindhoven, NL-5656, NL)
| 1. | A display device (1) having a front plate (7) secured to a display device main body (3) wherein, at points near a perimeter of the front plate, a number of brackets (8) are affixed to the front plate, which brackets are at least partially made of UV transparent material, and the front plate and/or the brackets comprise an injection channel (81) for providing glue between the brackets and the front plate, the brackets having means of attachment (85, 9) to a main body holder (4) and being attached to said main body holder. |
| 2. | A display device as claimed in claim 1, wherein the injection channel (81) is provided in the brackets. |
| 3. | A display device as claimed in claim 1, wherein the attachment means (85, 9) are provided at a side of the bracket opposite the side of the bracket affixed to the front plate. |
| 4. | A display device as claimed in claim 1, wherein the main body holder is a framework (4) around the main body and is provided with apertures (4a), while the brackets are attached to the main body holder (4) via attachment means (9) passing through the apertures (4a). |
| 5. | A display device as claimed in claim 4, wherein the apertures (4a) are oversized. |
| 6. | A display device as claimed in claim 1, wherein the bracket (8) is provided with a recess (82) for the UV glue at the side facing the front plate and an air escape channel (84, 85) in said recess. |
| 7. | A display device as claimed in claim 6, wherein the brackets (8) have at least two air escape channels, one (85) at the center of the bracket and one (86) at a perimeter. |
| 8. | A display device as claimed in claim 1, wherein the brackets are provided with stiffening fins (86). |
| 9. | A display device as claimed in claim 1, wherein the front plate is positioned in such a way that an air gap is provided between the front plate (7) and the main body (3) surface. |
| 10. | A method of securing a front plate (7) to a display device main body (3), wherein a front plate (7) is provided, while brackets (8) at least partially made of UV transparent material are positioned on the front plate (7), and UV glue is injected between the brackets (8) and the front plate(7), which UV glue is subsequently hardened by exposure to UV light, whereafter the front plate (7) is attached to a main body holder (4) via the brackets (8). |
FIELD OF THE INVENTION
The invention relates to a display device having a front plate secured to a display device main body. The invention also relates to a method of securing a front plate to a display device main body.
BACKGROUND OF THE INVENTION
Such a display device is known from United States Patent 6,833,665. In the prior art, the front plate is secured to a flat panel display main body by means of an adhesive layer between the front plate and the viewer's side surface of the display device main body.
The use of an adhesive layer has the disadvantage that great care must be taken that the adhesive layer is properly cured. Furthermore, the front plate is intimately secured to the main body and any difference in temperature may lead to thermal stresses, which can lead to unwanted breakage or unwanted optical effects. Considerable heat may be produced in the display panel main body, especially in plasma display flat panel devices, which may lead to thermal stresses.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a display device in which the securing operation is easier, and the above-mentioned problems are at least partly mitigated.
To this end, the display device is characterized in that, at points near a perimeter of the front plate, a number of brackets are affixed to the front plate, which brackets are at least partially made of UV transparent material, and the front plate and/or the brackets comprise an injection channel for providing glue between the brackets and the front plate, the brackets having means of attachment to a main body holder and being attached to said main body holder.
The front plate is provided with brackets near the perimeter (edge) of the front plate. These brackets are affixed to the front plate by means of UV glue. The front plate or brackets, preferably the brackets, are provided with an injection channel to inject UV glue between the brackets and the front plate. The brackets are at least partly made of UV transparent material, which allows the UV glue to be hardened by UV light so that the bracket is affixed to the front plate.
The brackets have means for attaching them to a main body holder. Via said attachment means, the brackets, and thereby the front plate, are attached to the main body holder and thus affixed to the main body. Within the scope of the invention, a 'main body holder' is a holder for the main body. The holder may form an integral part (for instance, an edge part) of the main body itself, or it may be a separate framework to which the main body is attached.
Although it may seem that, as in the prior art, the problem of curing the adhesive is still present, any problems due to less than perfect curing are greatly reduced. In the display device of the invention, any problem with curing can be easily tested optically and/or mechanically before the front plate is positioned and the connection between the front plate and the main body is made, and even if such problems are experienced at a later stage, a front plate can be easily removed without needing to damage the main body. In the prior art, any problem with curing of the adhesive between the front plate and the main body directly leads to irreparable loss of the display device as a whole. Moreover, any optical effect of imperfections on curing of the adhesive are not visible or hardly visible in a display device according to the invention, because they are located at the perimeter of the front plate, outside the display area, and thus do not necessarily have a negative effect on the image quality, whereas in the prior art any optical effects are clearly visible and thus reduce the image quality.
The attachment means are preferably provided at a side of the brackets opposite the side of the bracket affixed to the front plate, i.e. the rear side (as viewed from the front plate) of the bracket. This allows easy fixation of the brackets to the main body holder.
The main body holder is preferably a framework around the main body and is provided with apertures, while the brackets are attached to the main body holder via attachment means (such as screws) passing through the apertures.
In a preferred embodiment, the bracket is provided with a recess for the UV glue at the side facing the front plate and an air escape channel in said recess. The air escape channel allows air to escape when the UV glue is injected, which prevents formation of air
bubbles. Air bubbles reduce the strength of the connection between the bracket and the front plate.
There are preferably at least two air escape channels, one at the center of the bracket, and one at a perimeter. This further reduces the risk of air bubbles. The front plate is preferably positioned in such a way that an air gap is provided between the front plate and the main body surface.
The air gap allows small deflections of the front plate.
The apertures in the main body holder are preferably larger than the screws. "Oversized' apertures allow some change in the size of the front plate with respect to the main body holder. Temperature differences may cause differences in thermal expansion and thereby a change in size.
The brackets are preferably provided with stiffening fins.
The method according to the invention is characterized in that a front plate is provided, while brackets at least partially made of UV transparent material are positioned on the front plate, and UV glue is injected between the brackets and the front plate, which UV glue is subsequently hardened by exposure to UV light, whereafter the front plate is attached to a main body holder via the brackets.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 illustrates, in a cross-section, various elements of a display device in a detached condition; Figs. 2 illustrates, in a cross-section, a part of a display device according to the invention;
Fig. 3 is a perspective view of a part of a display device according to the invention;
Fig. 4 illustrates a bracket; Fig. 5 shows a bracket in various perspective views;
Fig. 6 illustrates a part of the method according to the invention;
Fig. 7 illustrates a main body holder with an oversized aperture.
The Figures are not drawn to scale. Generally, identical components are denoted by the same reference numerals in the Figures.
DESCRIPTION OF EMBODIMENTS
Fig. 1 illustrates various elements of a display device 1 according to the invention. The display device 1 comprises a display device main body section 2, which comprises the display device main body 3, i.e. the actual flat display, such as a PDP or LCD display panel, and a holder 4 for the display device main body 3. In this example, the main body section also comprises a dust protection layer 5.
The display device further comprises a front plate section 6, which comprises a front plate 7 and a bracket 8. In this example, the front plate section 6 and the main body section 2 are connected via a screw 9 which passes through apertures in main body holder 4 and is screwed into bracket 8. The brackets 8 are provided at a number of points at or near the perimeter (edge) of the front plate 7. To this end, the holder 4 is provided with apertures 4a. A washer 10 is also provided. Screwing is one of the possible ways of attaching the brackets to the holder 4. Other means may be, for instance, a 'click-on' type of attachment in which the bracket has protrusions which are forced through apertures in the holder, and, once forced through said apertures, affix the bracket to the holder. The brackets may also have a bolt through the aperture, in which case a nut may be used to affix the bracket to the holder. The front plate may have several functions such as reduction of EMC radiation, anti-reflective properties, or protection properties.
In this example, an EMC (radiation) reducing sheet 11 is provided between the front plate section 2 and the main body section 6. The EMC reducing sheet is, for instance, a foam sheet provided between the front plate 7 and the holder 4. The sheet is partially compressed to, for instance, approximately 50% of the uncompressed thickness. The sheet 11 establishes electrical contact between the front plate 7 and the holder 4.
In this example, the device is further provided with an inner casing 12, which may have the function of an EMC shielding frame, in particular when the display is a PDP display, attached to the holder 4 and back and front outer casings 13 and 14. In this example, a front outer casing 14 is shown. Such a front outer casing is often simply called 'the front'. An advantageous embodiment of the invention is characterized in that the display device does not comprise a front outer casing. This allows a design of a display device with a completely flat front, without the need of a front outer casing. It is to be noted that the invention offers a substantial advantage in comparison with designs using a front plate which is held in place by a front outer casing. The front outer casing needs to have a substantial
strength to hold a front plate, especially for larger size displays. Such an outer casing is costly.
Figure 2 illustrates a detail of a device according to the invention, in which the front plate 7 is affixed to the main body via the brackets 8. A small air gap having the thickness of compressed sheet 11 is present between the front plate 7 and the display main body 4. This air gap allows the front plate 7 to flex without it touching the main body.
Figure 3 is a perspective view showing the fixation of the front plate 7 to the main body holder 4 via the brackets 8 and screws 9. The main body 3 is attached to the main body holder 4. Figure 4 shows a bracket in a cross-section. The bracket may have various shapes. It may have, for instance, a simple flat surface. Figure 4 shows a somewhat more complex design in which the bracket is provided with a recess. The bracket 8 comprises an injection channel 81 for injection of UV glue, a recess 82 surrounded by a groove 83 at a perimeter, an air escape channel 84 at a perimeter connected with the groove through which air may escape, and an air escape channel 85 at the center of the bracket. The central air escape channel 85 also forms part of the attachment means, because screw 9 is screwed into the upper end of the air escape channel. Figure 5 shows the same bracket in various perspective views. In this example, the bracket is round. Within the scope of the invention, the bracket may have various shapes, including a round, a square, or a rectangular shape, etc. The recess in the brackets as well as the brackets themselves are preferably rounded, i.e. round, roundish or oval, i.e. they do not have corners. Corners in the recess may restrict the flow of UV glue, which could lead to air pockets in the glue. Sharp corners may be the starting point of cracks in the brackets.
Figure 6 illustrates a step in the method of manufacturing a display device according to the present invention.
A bracket 8, which is at least partly made of UV transparent material, is positioned on a front plate 7. UV glue is injected between the bracket and the front plate. In the shown bracket 8, the UV glue is injected via the injection channel 81 (see Figures 4 and 5) of the bracket. The glue fills the recess 82, whereby the air escapes through the air escape channel 84 (see Figures 4 and 5) and air escape channel 85. Within the scope of the invention, an injection or air escape 'channel' is to be understood to be any means via which glue may be injected or air may escape. It may thus be a simple hole. Once the recess 82, and possibly at least part of the rest of the bracket is filled with UV glue, i.e. with glue that hardens under UV radiation, a UV light source is used to harden the UV glue. The advantage
of using a glue injection is that the amount of glue can be controlled very accurately as regards quantity and area, so that it does not easily spill. Subsequently, the brackets are positioned on the main body holder, and a screw with a washer is used to fasten the brackets, or another type of attachment means is used with which the front plate is attached to the main body holder. The main body may be attached to the main body holder before or after attaching the front plate to the main body holder.
The apertures 4a in the main body holder 4 are preferably oversized, for instance, oval. The apertures in the main body holder are preferably larger than the screws. "Oversized' apertures allow some change in size of the front plate with respect to the main body holder. Temperature differences may cause differences in thermal expansion and thereby a change in size. Figure 7 illustrates an oval aperture 4a in the main holder 4.
In summary, a display device according to the invention may be described as follows.
A display device has a front plate which is secured to a display device main body. At a number of points near its perimeter, the front plate is provided with a number of brackets affixed to the front plate. The brackets are at least partially made of UV transparent material, and the front plate or the brackets comprise an injection channel to provide glue between the bracket and the front plate. The brackets have means of attachment to a main body holder and are attached to said main body holder. The method according to the invention may be described as follows.
A front plate (7) is secured to a display device main body (3). The front plate (7) is provided with brackets (8) which are at least partially made of UV transparent material. The brackets are positioned on the front plate (7). UV glue is injected between the bracket (8) and the front plate (7). The UV glue is subsequently hardened by exposure to UV light, whereafter the front plate (7) is attached to a main body holder (4) via the brackets (8). It will be clear that many variations are possible within the scope of the invention. It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. The invention resides in each and every novel characteristic feature and each and every combination of characteristic features. Reference numerals in the claims do not limit their protective scope. Use of the verb "comprise" and its conjugations does not exclude the presence of elements other than those stated in the claims. Use of the article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
For instance, in all examples, the injection channel is provided in the brackets. An injection channel may be provided in the front plate, especially if the front plate is not made of glass. However, it is preferred that the injection channels are provided on the brackets. Injection channels in the front plate would require a hole in the plate. The front plate may be made of glass or any other transparent material.