Rear projection type television receiver

A rear projection type television receiver of the invention comprises a cabinet having a built-in television receiver, and a screen assembly. The cabinet has a rectangular groove formed around the circumference of the front edge portion. The screen assembly has screen holding plates elastically coupled to each side of the screen, and screen frames coupled to screen holding plates. The screen frames are coupled in a rectangular form. The screen assembly is coupled with the cabinet when the screen frames are inserted into the front groove of the cabinet.

FIELD OF THE INVENTION 
The present invention relates to a rear projection type television receiver 
for displaying an image projected on a rear side of a transmission type 
screen (hereinafter called screen). The rear projection type television 
receiver can be used either alone or in a large-screen display composed of 
multiple units. 
BACKGROUND OF THE INVENTION 
FIG. 7 shows the screen holding assembly of a conventional rear projection 
type television receiver. On the rear side of a screen 3, an image 66 is 
projected from a television receiver (not shown) incorporated in a cabinet 
63. The screen 3 inserted in a lower groove 64 of the cabinet is held in 
the cabinet 63 by a screen holding frame 62 inserted in an upper groove 65 
of the cabinet. Temperature rise during use and increase of ambient 
humidity will expand the screen 3. A gap 61 absorbs the expansion of the 
screen 3. If, for example, the screen 3 has a length of 900 mm, the length 
will be increased by about 3.5 mm based on expected increase of 
temperature and humidity. Therefore a length of 3.5 mm is required for the 
gap 61. As a result, as shown in FIG. 7, a width W of about 5 mm is 
required for the rim of the screen. FIG. 8 shows a wide-screen display 
composed of nine rear projection type television receivers. Plural dark 
screen rims R of about 10 mm in width cross the screen surface and lower 
the screen quality. It is hence an object of the invention to present a 
rear projection type television receiver with a decrease rim width around 
the screen in order to realize a wide screen of high picture quality. 
SUMMARY OF THE INVENTION 
The rear projection type television receiver of the invention is 
constructed by coupling a cabinet and a screen assembly. In the screen 
assembly, the screen is held by a screen holding plate elastically coupled 
to each side of the screen. This elastic coupling absorbs the screen 
expansion. Therefore, the screen assembly does not require a gap for 
absorbing the screen expansion. As a result, the width of the rim around 
the screen is decreased, so that a wide screen of high quality is realized 
.

EXEMPLARY EMBODIMENT 
The rear projection type television receiver of the invention comprises, as 
shown in FIG. 1, a cabinet 2 incorporating a television receiver, and a 
screen assembly 1. The screen assembly 1 is fitted to the cabinet 2 by 
inserting a screen frame 9 into a rectangular groove 15 formed around on 
the front face of the cabinet, and is fixed to the cabinet 2 by fasteners 
4 (described herein). There are four fasteners 4 in FIG. 1. The screen 
assembly 1 can be detached from the cabinet 2 by unlocking the fasteners 
4. 
FIG. 2 and FIG. 3 show the construction of the screen assembly 1. As shown 
in FIG. 2, screen holding plates 5, 6, 7, 8 are elastically adhered to 
each side of the screen 3, and coupled by coupling means 10. Corner plates 
11 cover the four corners so that projected light may not escape outside. 
The screen frame 9 is fitted, in a rectangular form, to the screen holding 
plates 5 through 8 and coupling means 10. FIG. 3 shows the completed shape 
of the screen assembly 1. 
FIG. 4 shows a section of the rear projection type television receiver of 
the invention. The screen assembly 1 is fitted to the cabinet 2 by 
inserting the front end of the screen frame 9 into the front groove 15 of 
the cabinet. The screen assembly 1 is smaller than the cabinet 2, by the 
distance D being 0.5 mm as shown in FIG. 4, so as not to interfere with 
another screen assembly when the rear projection type television receivers 
are stacked. 
The screen holding plates 5 to 8 (7, 8 are not shown) have a folded rim 
having a short width WR of 0.8 mm. The difference in expansion of the 
screen holding plates and screen 3 is absorbed by the elasticity of an 
adhesive sheet 12, and thus holding the screen is possible with a rim of 
short width. The screen assembly 1 will not be destroyed by the difference 
in expansion. 
Through the adhesive sheet 12, the bottom of the screen 3 and the screen 
frame 9 are adhered to the screen holding plate 5, the upper side of the 
screen 3 and the screen frame 9 are adhered to the screen holding plate 6, 
and, although not shown, the right side of the screen 3 and the screen 
frame 9 are adhered to the screen holding plate 7, and the left side of 
the screen 3 and the screen frame 9 are adhered to the screen holding 
plate 8. That is, the screen 3 is held between the screen rim and the 
screen frame 9 adhered to the screen holding plate 7. 
When multiple rear projection type television receivers are stacked up in a 
rectangular form to make a wide screen, it is preferred that each screen 
rim be aligned vertically and horizontally. To realize this, the bottom of 
the screen 3 is tightly fitted and fixed to the cabinet 2 so as to 
maintain a precise relative position, in the vertical and horizontal 
direction, to the cabinet 2. The upper side, left side and right side of 
the screen 3 are loosely fitted so as to be free to move along with 
expansion of the screen 3. In FIG. 4, the upper side screen frame 9 and 
right and left screen frames 9 (not shown) differ in shape from the lower 
side screen frame 9. 
The screen 3 is composed of lamination of lenticular lens sheet 21 and 
Fresnel lens sheet 22 both made of acrylic resin. In most cases, the 
thickness of the lenticular lens sheet 21 is 0.5 to 1.5 mm, and the 
thickness of the Presnel lens sheet 22 is 2 to 3 mm. Temperature rise and 
increase of ambient humidity cause both lens sheets to expand, but the 
lenticular lens sheet 21 expands more than the Fresnel lens sheet 22. 
Therefore, if the sides of both lens sheets are adhered to the screen 
holding plates 5 to 8, the screen 3 will be distorted, or broken in a 
worst case, due to changes in temperature and humidity. Screen distortion 
must be avoided because this causes the image to be distorted. To avoid 
the distortion, in the invention, the Fresnel lens sheet 22 is adhered to 
the screen holding plate only on the bottom side, while all four sides of 
the lenticular lens sheet 21 are adhered to the screen holding plates. The 
sides other than the bottom side of the Fresnel lens sheet 22 are not 
adhered to the screen holding plates. This can be accomplished by setting 
the size of the Fresnel lens sheet 22 slightly smaller than the size of 
the lenticular lens sheet 21. 
Next, the fastening of the screen assembly to the cabinet is explained,. 
FIG. 5 shows a lock wedge 51. The screen assembly is attached to the 
cabinet by pushing in the lock wedge 51. To the contrary, the screen 
assembly is separated from the cabinet by pulling out the lock wedge 51. 
The lock wedge 51 fits into a groove 17 of the screen frame 9, and is 
moveably positioned in the screen assembly 1. When the screen assembly 1 
is fitted in the cabinet 2, the lock wedge 51. will be at the position 
indicated by broken line in FIG. 6(b). Attaching the screen 3 into the 
cabinet 2 is effected by pushing the lock wedge 51 into the cabinet 2 as 
shown in FIGS. 6(a) and 6(b). As shown in FIG. 6(a), the tapered end of 
the lock wedge 51 is pushed in and, when the lock position is reached, 
expands two lock pins 52 movable along a groove 58 of the cabinet 2. Each 
lock pin 52 holds the dent 56 so as to lock the screen frame 9 in 
position. As a result, the screen 3 is fixed to the cabinet 2. 
To separate the screen assembly 1 from the cabinet 2, the lock wedge 51 is 
pulled out. As shown in FIG. 5, the lock wedge 51 has a bulge 53 adapted 
for insertion of a finger or a tool to pull out the lock wedge 51 as shown 
in FIG. 6(b), a shoulder 54, and a slope 57 for hooking on a pawl to be 
used when removing the screen assembly 1. The slope 57 provides the lock 
wedge 51 with an elasticity for preventing the lock wedge 51 from slipping 
out of the lock position. As shown in FIG. 6(b), when the lock wedge 51 is 
pulled out, the shoulder 54 interferes with the end portion 59 of the 
screen frame 9. As a result, the screen assembly 1 is separated from the 
cabinet 2, together with the lock wedge 51, by pulling-out the lock wedge 
51. 
The invention may be embodied in other specific forms without departing 
from the spirit or essential characteristics thereof. The present 
embodiment is therefore to be considered in all respects as illustrative 
and not restrictive, the scope of the invention being indicated by the 
appended claims rather than by the foregoing description and all changes 
which come within the meaning and range of equivalency of the claims are 
therefore intended to be embraced therein.