GB2108700A - Improvements in or relating to video projectors - Google Patents

Abstract

Video projection apparatus has a support 20 on which a television set may be placed. A hood 40 is arranged relative to the support whereby the hood may be arranged to contact the periphery of the television screen in mechanical alignment therewith. The hood is configured to direct an image from said television screen towards projection optics 70 mounted at one end of the hood remote from the screen. The projection optics comprise a barrel housing an optical system. This barrel is received in a mounting barrel adapted for mounting, in an opening in the hood, by a mount which permits mechanical adjustment thereof with respect to the hood such as to allow optical alignment of the projection optics with the television screen. <IMAGE>

Description

SPECIFICATION Improvements in or relating to video projectors This invention relates to improvements in or relating to video projection apparatus.

More especially this invention is concerned with video projection apparatus by means of which the television picture displayed on the screen of a television set may be projected onto a projection screen.

It is known to provide video projection apparatus in which a television receiver may be mounted with a hood adjacent the face of the television screen, the hood carrying projection optics for projecting an image from the television screen onto a projection screen.

The known apparatus suffers from the defect that the picture definition on the projection screen is impaired if there is not a sufficiently accurate mechanical alignment between the optical planes and axis of the projection optics and an optical plane of the television screen. Factors which are important to the correct setting of this mechanical alignment include (a) the mechanical relationship of the television tube to the television cabinet which is likely to vary from set to set since the sets themselves whilst being assembled in a uniform manner nevertheless display differences in mechanical alignment which only subsequently becomes significant in the context of the optical alignment required for video projection when the screen image is magnified, (b) the mechanical assembly of the television set in relation to the hood carrying the projection optics, and (c) the mechanical relationship of the projection optics to the hood in which said projection optics are mounted, which are found to lack optical precision when the projection optics are fixedly mounted relative to the hood during assembly of the video projection apparatus.

Also, the prior art video projection apparatus lacks the facility for adjusting the angle of projection of the apparatus onto a projection screen whereby the angte of projection may be adjusted for different screen sizes and locations of the apparatus with respect to the screen as will vary from one user to another.

Thus, the present invention seeks to provide a preferred embodiment in which these disadvantages are overcome.

According to one aspect of the present invention there is provided video projection apparatus comprising support means on which a television set may be placed, hood means arranged in juxtaposed relation to the support means whereby the hood means may be arranged to contact the periphery of the television screen in mechanical alignment therewith, said hood means being configured to direct an image from said television screen towards projection optics mounted at one end of the hood means remote from the end thereof adapted for mechanical alignment with the television screen, said projection optics comprising a barrel housing an optical system, the barrel being received in a mounting barrel adapted for mounting in an opening in the hood means at said one end of the hood means, said mounting barrel being mounted by mounting means which permit mechanical adjustment thereof with respect to the hood means such as to allow optical alignment of the projection optics with the television screen.

In the preferred embodiment the mounting barrel extends from a peripheral mounting plate arranged in a plane normal to the axis thereof, and a series of adjustment members extend from said mounting plate to engage said one end of the hood means and secure the mounting barrel thereto, each adjustment member being independently adjustable as to the length thereof which so extends between the mounting plate and said one end of the hood means.

In one embodiment, the mounting barrel is provided with a rectangular mounting plate and an adjustment member is located in the region of each corner of said mounting plate. The end wall may be provided with bores for each adjustment member. These bores may be a clearance fit for the adjustment members which may threadedly engage threaded apertures in the mounting plate and resilient means may act between said mounting plate and said one end of the hood means to space them apart according to the length of the adjustment members.

Thus, rotation of an adjustment member will adjust the length of that adjustment member acting between its associated bore in the end face of the hood means and its associated threaded aperture in the mounting plate. It will be readily apparent that by actuation of the adjustment members the projection optics can be optically aligned with the television screen. Whilst the preferred embodiment has four, rectangularly placed, adjustment members, it will be appreciated that full adjustment can be achieved with other configurations of the adjustment members, for example three, triangularly placed adjustment members.

In the preferred embodiment, the support means for the television set and the hood means are fixedly connected together, and the support means is pivotally mounted on and angularly adjustable relative to a framework for the apparatus, angular adjustment being accomplished by means of rotating a threaded member which is carried by either said support means or said framework and threadedly engageable with the other of said support means or framework.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows schematically and in perspective view a video projection apparatus without a television set thereon; Figure 2 shows in elevation a fragmentary view of the apparatus of Figure 1 illustrating the means by which the angle of projection may be varied; Figures 3A and 3B show schematically the mounting barrel of the apparatus of Figure 1 in an elevational view and a frontal view (only Figure 3A shows schematically a projection optics barrel in the mounting barrel); Figure 4 shows schematically and in elevation part of the apparatus of Figure 1 with a television set placed thereon; Figure 5 shows schematically a plan view of the hood means of the apparatus of Figure 1; and, Figure 6 shows detail of a modification of the mounting means.

Fig. 1 of the drawing illustrates schematically video projection apparatus 10 having support means 20 on which a television set 50 (Fig. 4) may be placed.

Support means 20 comprises a pair of vertically spaced transversely extending members 21, 22 the upper one 21 of these members being arranged to be pivotal about a framework 30. The support members 21,22 are connected at the lateral sides of the support means by upright members 23. A pair of rearwardly extending support members 24 project rearwardly from member 22 and are connected at their rearward ends by member 25. The support members 24 and 25 define a frame into which a television set 50 can be placed and supported thereon as shown in Fig. 4.

Hood means 40 are arranged in juxtaposed relation to the support means 20 whereby the hood means 40 may be arranged to contact the periphery of the television screen 51 (Fig. 4) in mechanical alignment therewith as shown in Fig.

4. The hood means 40 (as shown in Figs.1,4 and 5) is configured to direct an image on said television screen 51 (Fig. 4) towards projection optics 70 mounted at one end 42 of the hood means 40 remote from the end 41 thereof adapted for mechanical alignment with the television screen 51. The projection optics 70 comprises a barrel housing an optical system. The barrel 71 is received in a mounting barrel 61 adapted for mounting in an opening in the hood means 40 at one end 42 of the hood means 40.

The mounting barrel is mounted by mounting means (to be further described) which permit mechanical adjustment thereof with respect to the hood means 40 such as to allow optical alignment of the projection optics 70 with the television screen 51.

As shown in Figs. 3 and 3A the mounting barrel 61 extends from a peripheral mounting plate 62 arranged in a plane normal to the axis of the barrel 61. A series of four adjustment members 63 extend from the mounting plate 62 to engage the end 42 of the hood means 40 and secure the mounting barrel 61 thereto. Each adjustment member 63 is independently adjustable as to the length thereof which so extends between the mounting plate 62 and one end 42 of the hood means 40. As will be readily apparent from Fig. 1 and Figs. 3, 3A, the mounting plate 62 is within the hood means 40 such that the barrel 61 projects outwardly through an opening of corresponding dimensions in the end 42.

The mounting barrel 61, as shown in Figs. 3, 3A is provided with a rectangular mounting plate 62 and an adjustment member 63 is located in the region of each corner of the mounting plate 62. The end wall 42 is provided with bores 43 for each adjustment member 63. These bores 43 are a clearance fit for the adjustment members 63.

Adjustment members 63 threadedly engage threaded apertures 64 in the mounting plate 62.

Resilient means (springs) 65 act between the mounting plate 62 and one end 42 of the hood means 40 to space them apart according to the length of the adjustment member 63 arranged therebetween.

Thus, rotation of an adjustment member 63 will adjust the length of that adjustment member 63 acting between its associated bore 43 in the end 42 of the hood means 40 and its associated threaded aperature 64 in the mounting plate 62.

It will be readily apparent that by actuation of the adjustment members 63, the projection optics 70 can be optically aligned with an optical plane of the television screen 51. Whilst the preferred embodiment has four rectangularly placed, adjustment members 63A to 63D (as shown in Fig. 3B) it will be appreciated that full adjustment can be achieved with other configurations of the adjustment members. For example three, triangularly placed adjustment members such as the members 63A, 63B of Fig. 3B and a third member 63 intermediate the positions of members 63C, 63D in Fig. 3B.

In this embodiment, as shown in Figs. 1 and 2, the support means 20 for the television set 50 and the hood means 40 are fixedly connected together, and the support means 40 is pivotally mounted at 31 on, and angularly adjustable relative to, the framework 30 of the apparatus.

Angular adjustment is accomplished by means of rotating a threaded member 81 which is carried by support means 20 and threadedly engageable with the framework 30.

Further constructional details of the present embodiment are as follows. In Fig. 1 the framework 30 defines a substantially rectangular cabinet carried on castors 32. The cabinet base defined by a pair of spaced longitudinal members 33 interconnected by lateral members 34 at the front and rear of the cabinet. Uprights 35 at four cabinet corners support an upper part of the framework defined by longitudinal members 36 and interconnecting rear member 37: members 36, 37 being vertically above and parallel to corresponding members 33, 34. Intermediate upright members 38 interconnecting members 33, 36 and intermediate the length of the cabinet, are provided at 31 with pivot means for pivotally connecting the support means 20 on the framework 3x3. Framework 3x3 may be clad on its sides (defined by members 33, 35 and 36) and rearward end (defined by members 34, 37 and 35) and top (defined by members 36, 37) in order to give the cabinet an acceptable appearance for use in the home (or other establishment). The cladding on top between the uprights 38 and 35 may be in two sections hingedly secured whereby these two hinged sections may be opened for removal or insertion of the television set 50, thus permitting the set to be also used in conventional manner.

In Fig. 2, the support means is seen to further comprise the member 26 which projects forwardly (in the context of the cabinet) from the member 21 (Fig. 1). Hood means 40 is rigidly connected to members 21 and 26 of the support means 20 by fasteners 27 as illustrated schematically in Fig. 2. Fig. 2 also indicates schematically the adjustment means 80 for adjusting the inclination of the support means 20 relative to the framework 30 and more particularly by pivoting the support means 20 (as indicated by arrow W) about the pivot means 31.

As seen from Fig. 2, member 28 depends from the mid-point of support member 21 (of Fig. 1) and member 39 extends upwardly from the framework 30 at the mid-point of a further cross member 34a interconnecting members 38 (Fig.

1). The adjustment means 80 has its spindle 81 arranged to threadedly engage a threaded aperature 82 in member 28 and extend through an aperture 83 of larger diameter in member 39.

Spindle 81 carries a manually rotatable handle 84 for rotation thereof and stops 85, 86 which limit the travel of spindle 82 relative to aperture 83.

Rotation of handle 84 in the appropriate sense, effects corresponding pivoting of the support means 20 (and thus the television set 50 and hood means 40) about the pivot means 31 as indicated by arrow W.

In Fig. 3, the adjustment members 63 have been already described. These members 63 may be described as bolts and at their heads 66 they are provided with cup-like members 67 (not shown) between the heads 66 and the spring (resilient means) 65. The heads 66 abuts the external face of the end 42 of hood means 40 (Fig. 1). The springs 65 urge the plate 62 to the maximum spacing thereof away from end 42 of hood means 40 permitted by the particular setting of the associated members 63. Thus, plate 62 may be tilted about an axis passing normally therethrough with respect to the planes of either of Figs. 3A and 3B. This enables mechanical alignment of the optical means 70 with the screen 51 by virtue of which optical alignment is also attained between the optics and the optical image plane of the screen 51.For improved appearance plastic caps are placed on the outer faces of heads 66 after the adjustment members 63 have been set. This also discourages 'inadvertent' rotation of members 63. The mounting barrel 61 and the barrel 71 of the projection optics 70 have machined inner and outer surfaces respectively for co-axial alignment thereof. Stops 67 permit the barrel 71 to be secured in position and facilitate adjustment of the longitudinal position of the barrel 71 relative to hood means 40 for adjusting the magnification for different projection screens sizes.

In Fig. 4 the hood means 40 is shown in mechanical alignment with the screen 51 of a television 50 supported on the support means 20.

The near end 41 of hood means 40 actually abuts the screen and the top and bottom edges of the hood means 43 at the end 42 are contoured to the configuration of the screen. The hood means 40 is assembled from steel sheet coated with black nylon. Steel gives the hood means 40 the rigidity necessary for stable mechanical aligment of the projection optics 70 with the television screen 51. The coating of this steel with black nylon reduces losses in illumination as the screen picture S (Fig. 5) is projected through the hood means 40 and the projection optics 70 to the projection screen (not shown).

Obviously, the quality of the projection optics 70 and the intensity of the screen picture S are important to the quality of the projected picture.

Applicant has been able to establish projection with his apparatus of high quality using a Sony Trinitron television set which has a high intensity screen picture and a projection lens with a triplex or quadruplex system especially developed for video projection. Such a lens system will have a high refractive index and will have fully colour corrected glass lenses which are coated with an anti-reflection coating for maximum light transmission and durability; these lenses allow 1100 field of vision. The mounting barrel 61 and projection lens barrel 71 are both coated with black anodised aluminium again to avoid stray light and losses in the intensity of the projected light.

In a modification the number of adjustment members 63 may be increased to be greater than four. The plate 62 may be circular.

A further modification is illustrated in Fig. 6 (like numerals indicate like parts). Fig. 6 shows schematically, and in exploded perspective view, an additional mounting arrangement wherein the mounting barrel 60 (similar to that of Fig. 3A) instead of being mounted directly onto the hood means 40 at end 42 thereof (as shown in Figs. 4 and 5) is first mounted onto a swivel bracket 90 (with bores 43 similar to those in hood means 40). Swivel bracket 90 is substantially U-shaped in configuration with an opening 91 matching the opening in the end 42 of the hood means 40.

Mounting barrel 60 instead of being mounted direction onto hood means 40, is mounted in similar manner to that already described in relation to Figs. 3a, 3b on swivel bracket 90 with the same facility for adjustment by means of adjustment members 63. Springs 65 serve the same purpose as aforementioned. Bracket 90 is itself adapted Tor pivotal mounting on the hood means 40 by means of pins (not shown) which pass through apertures 92 and are received in the side walls of hood means 40, which may be readily adapted for the purpose (but is not illustrated). The swivel bracket 90 permits the apparatus to be used with different screen heights.

Claims (9)

Claims

1. Video projection apparatus comprising support means on which a television set may be placed, hood means arranged in juxtaposed relation to the support means whereby the hood means may be arranged to contact the periphery of the television screen in mechanical alignment therewith, said hood means being configured to direct an image from said television screen towards projection optics mounted at one end of the hood means remote from the end thereof adapted for mechanical alignment with the television screen, said projection optics comprising a barrel housing an optical system, the barrel being received in a mounting barrel adapted for mounting in an opening in the hood means at said one end of the hood means, said mounting barrel being mounted by mounting means which permit mechanical adjustment thereof with respect to the hood means such as to allow optical alignment of the projection optics with the television screen.

2. Apparatus as claimed in Claim 1, wherein the mounting barrel extends from a peripheral mounting plate arranged in a plane normal to the axis thereof, and a series of adjustment members extend from said mounting plate to engage said one end of the hood means and secure the mounting barrel thereto, each adjustment member being independently adjustable as to the length thereof which so extends between the mounting plate and said one end of the hood means.

3. Apparatus as claimed in Claim 2, wherein the mounting barrel is provided with a rectangular mounting plate and an adjustment member is located in the region of each corner of said mounting plate.

4. Apparatus as claimed in Claim 3, wherein the end wall may be provided with bores for each adjustment member.

5. Apparatus as claimed in Claim 4, wherein these bores may be a clearance fit for the adjustment members which may threadedly engage threaded aperatures in the mounting plate and resilient means may act between said mounting plate and said one end of the hood means to space them apart according to the length of the adjustment members.

6. Apparatus as claimed in Claim 1, further comprising a swivel bracket provided with an aperture to receive said mounting barrel and pivotally mounted on said hood means with its aperture in alignment with said opening, said swivel bracket being adapted for the mounting of said mounting barrel thereon.

7. Apparatus as claimed in Claim 6, wherein the mounting barrel extends from a peripheral mounting plate arranged in a plane normal to the axis thereof, and a series of adjustment members extend from said mounting plate to engage said swivel bracket and secure the mounting barrel thereto, each adjustment member being independently adjustable as to the length thereof which so extends between the mounting plate and the swivel bracket.

8. Apparatus as claimed in any one of Claims 1 to 8, wherein the support means for the television set and the hood means are fixedly connected together, and the support means is pivotally mounted on and angularly adjustable relative to a framework for the apparatus, angular adjustment being accomplished by means of rotating a threaded member which is carried by either said support means or said framework and threadedly engageable with the other of said support means or framework.

9. Video projector apparatus arranged, constructed and adapted to operate substantially as hereinbefore described with reference to Figs.

1 to 5, or Figs. 1 to 5 as modified by Fig. 6, of the accompanying drawings.