Rear projection type television receiver

Abstract: A rear projection type television receiver of the invention comprises a cabinet having a built-in television receiver, and a screen assembly. The cabinet (2) has a rectangular groove (15) formed around the circumference of the front edge portion. The screen assembly has screen holding plates (5,6,7,8) elastically coupled to each side of the screen, and screen frames coupled to screen holding plates, and the screen frames are mutually coupled in a rectangular form. The screen assembly is coupled with the cabinet as the screen frames mutually coupled in a rectangular form are fitted and inserted into the front groove of the cabinet.

Description: 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 large-screen display composed of multiple units. Fig. 7 shows screen holding 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 by an 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 the diagram, a width 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 of about 10 mm in width crossing the screen surface are lowering the screen quality. It is hence an object of the invention to present a rear projection type television receiver decreased in the width of the rim around the screen in order to realize a wide screen of high picture quality. In our earlier application EP-A-0623839 which was published after the printing date of the present application we disclosed a projection type television receiver in which the screen is maintained on the framework despite temperature changes or external force application, and also a large screen video display apparatus which displays video images with minimal loss of picture area, characterized by easy installation or removal of the screen holding frameworks and which is excellent in maintainability. A plurality of projection type television receivers are arranged in multiple rows and lines for the purpose of displaying a large screen video image. Each projection type television receiver comprises a permeable screen with a screening effect, a framework for holding the permeable screen, an elastic member one surface of which is fixed to the peripheral end part of the permeable screen and the other surface of which is fixed to the framework's holding part of the permeable screen, and which is readily deformable according to applied external force, and a cabinet having its opening installed within the framework. The present invention provides a rear projection type television receiver comprising: a cabinet having a built-in television receiver, said cabinet being rectangular in cross-section at its front face and having a front groove along its front edge, a screen assembly comprising: a screen, a rectangular screen frame comprising screen holding plates elastically coupled with each side of the screen, said screen assembly being coupled with the cabinet as the rectangular screen frame is fitted and inserted into the front groove of the cabinet, and at least one fixing means for fixing the screen assembly, which has been fitted and inserted into the front groove of the cabinet, to the cabinet, characterised in that the fixing means for fixing the screen assembly to the cabinet comprises a lock wedge slidably inserted to the edge portion of the screen from the front side perpendicularly to the screen, a lock pin coupled to the cabinet, movably in the direction parallel to the screen, and not movably in the direction perpendicular to the screen, and a dent formed in the screen frame, wherein when the lock wedge is pushed in, the tip of the lock wedge pushes out the lock pin in the movable direction so that the lock pin holds the dent of the screen frame, resulting in the movement of the screen frame in the direction perpendicular to the screen being locked, thereby fixing the screen assembly to the cabinet. In order that the present invention be more readily understood an embodiment thereof will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a perspective exploded view of a rear projection type television receiver of the invention; Fig. 2 is a perspective exploded view showing the constitution of a screen assembly; Fig. 3 shows a completed shape of the screen assembly; Fig. 4 is a sectional view of the screen holding of the rear projection type television receiver of the invention; Fig. 5 shows a lock wedge used in fixing of the screen assembly to a cabinet; Fig. 6(a), (b) show fixing of the screen assembly to the cabinet; and Fig. 7 shows screen holding of a convention rear projection type television receiver. Fig. 8 shows multiple rear projection type television receivers stacked up for making up a wide screen. 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 fixing means 4 (see later). There are four fixing means 4 in Fig. 1. The screen assembly 1 can be detached from the cabinet 2 by unlocking the fixing means 4. Fig. 2 and Fig. 3 show the constitution of the screen assembly 1. As shown in Fig. 2, screen holding plates 5, 6, 7, 8 are elastically adhered to each size of the screen 3, and coupled by coupling means 10. Corner plates 11 cover 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 to 8 and coupling means 10, and is shape in a rectangular form. Fig. 3 shows a 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 formed smaller than the cabinet 2, by 0.5 mm smaller in the drawing, so as not to interfere with other screen assembly when stacked up with other rear projection type television receiver. The screen holding plates 5 to 8 (7, 8 are not shown) have a folded rim of short width. The difference in expansion of the screen holding plates and screen 3 is absorbed by the elasticity of an adhesive sheet 12, and holding of screen is enough 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 up a wide screen, it is preferred that each screen rim be aligned neatly 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. Because of this reason, 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 Fresnel lens sheet 22 is 2 to 3 mm. Temperature rise and increase of ambient humidity cause to expand both lens sheets, but the lenticular lens sheet 21 expand 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. Such distortion must be avoided because the image is 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 other sides than the bottom side of the Fresnel lens sheet 22 are not adhered to the screen holding plates. It can be realized by setting the size of the Fresnel lens sheet 22 slightly smaller than the size of the lenticular lens sheet 21. Next is explained the fixing means for fixing the screen assembly to the cabinet. Fig. 5 shows a lock wedge 51. The screen assembly is fixed to the cabinet by pushing in the lock wedge 51. To the contrary, the screen assembly is separated from the cabinet by drawing out the lock wedge 51. The lock wedge 51 fits into a groove 17 of the screen frame 9, and is movably put into 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). Fixing of the screen 3 into the cabinet 2 is effected by pushing the lock wedge 51 into the cabinet 2 as shown in Fig. 6 (a), (b). As shown in Fig. 6 (a), the tapered end of the lock wedge 51 pushed in and on reaching the lock position expands the spacing between two lock pins 52 movable along a groove 58 of the cabinet 2, and each lock pin 52 is received in a dent 56 in the frame 9 so as to lock the screen frame 9. 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 drawn out. As shown in Fig. 5, the lock wedge 51 has a bulge 53, a shoulder 54, and a slope 57 with the bulge 53 being used when drawing out the screen assembly 1. The slope 57 provides the lock wedge 51 with an elasticity for preventing the lock wedge 51 from slipping off the lock position. As understood from Fig. 6 (b), when the lock wedge 51 is drawn out, the shoulder 54 engages 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 drawing-out of the lock wedge 51.

Claims: A rear projection type television receiver comprising: a cabinet (2) having a built-in television receiver, said cabinet being rectangular in cross-section at its front face and having a front groove (15) along its front edge, a screen assembly (1) comprising: a screen (3), a rectangular screen frame (9) comprising screen holding plates (5,6,7,8) elastically coupled with each side of the screen (3), said screen assembly (1) being coupled with the cabinet (2) as the rectangular screen frame is fitted and inserted into the front groove of the cabinet, and at least one fixing means for fixing the screen assembly (1), which has been fitted and inserted into the front groove (15) of the cabinet, to the cabinet, characterised in that the fixing means for fixing the screen assembly to the cabinet comprises a lock wedge (51) slidably inserted to the edge portion of the screen from the front side perpendicularly to the screen, a lock pin (52) coupled to the cabinet (2), movably in the direction parallel to the screen, and not movably in the direction perpendicular to the screen, and a dent (56) formed in the screen frame (9), wherein when the lock wedge (51) is pushed in, the tip of the lock wedge pushes out the lock pin (52) in the movable direction so that the lock pin holds the dent (56) of the screen frame, resulting in the movement of the screen frame in the direction perpendicular to the screen being locked, thereby fixing the screen assembly to the cabinet. A rear projection type television receiver of claim 1, wherein the fitting of the screen frame (9) to the front groove of the cabinet (2) is tight at least in one side of the rectangle, and loose in the other sides. A rear projection type television receiver of claim 1, wherein each of said screen holding plates (5,6,7,8) has a folded end and are coupled with each other in a rectangular form, and wherein each side of the screen is held between the folded end of the screen holding plate (5,6,7 and 8) and the front edge of the screen frame, and the front edge of the screen is covered with the folded ends of the screen holding plates. A rear projection type television receiver of claim 1, wherein the screen is composed of lamination of lenticular lens sheet and Fresnel lens sheet, and the length of each side of the lenticular lens sheet is longer than the length of each corresponding side of the Fresnel lens sheet. A rear projection type television receiver of claim 4, wherein each side of the lenticular lens sheet is coupled to the screen holding plate, and the Fresnel lens sheet is coupled to the screen holding plate only by one side. A rear projection type television receiver of claim 1, wherein the base portion of the lock wedge has a folded portion which becomes a rim of a front face of the screen when the lock wedge is fully pushed in. A rear projection type television receiver of claim 6, wherein the folded portion at the base portion of the lock wedge has a bulge (53) for assisting removal of the wedge. A rear projection type television receiver of claim 1, wherein the lock wedge has a protruding or shoulder shaped portion (54) in the middle, and when the lock wedge (51) is pulled out to the outside, the protruding or shoulder shaped portion (54) of the lock wedge engages with the screen assembly, and thereby the screen assembly is separated from the cabinet by pulling-out of the lock wedge.

Inventors: GOTOU KAZUMI, MAEDA YOSHINOBU, SHIMATANI TSUYOSHI, TOZUKA MASAHIRO, YAMADA TADAYOSHI, GOTOU, KAZUMI, MAEDA, YOSHINOBU, SHIMATANI, TSUYOSHI, TOZUKA, MASAHIRO, YAMADA, TADAYOSHI
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1995
Main classification: H04N5
IPC codes: G03B21, H04N5