Optics: image projectors – Shutter
Patent
1991-12-27
1993-05-25
Cuchlinski, Jr., William A.
Optics: image projectors
Shutter
353 97, 353DIG3, 353 98, G03B 2312
Patent
active
052144593
DESCRIPTION:
BRIEF SUMMARY
The objective of this invention is an overhead projector (OHP) fitted with an acetate film roll, which consists of a body and its relevant projection arm fitted with a lens or lenses and a mirror.
In the existing OHP's, the acetate film rolls are usually assembled as extra elements onto fixed holders. These holders are usually fixed onto the body of the projector. One disadvantages of fixing the acetate film rolls in this conventional way is that when it is necessary to perform maintenance work, like changing a lamp, it is necessary to take the rolls off before being about to open the top and have access to the inside of the body. There is a further problem in the conventional OHP's and that is that when there is a need to cover part of the projected image, like in lectures and demonstrations, this is done by using extra sheets of paper or equivalent on top of the image. This makes the use of the OHP quite clumsy.
The main objective of the invention being presented is to decrease or eliminate the above causes of problems or disadvantages, and generally to improve the usefulness of the OHP. In order to implement the main objectives of the invention, the items presented in the patent claim 1 are characterized of the OHP.
The invention is shown in relation to the enclosed drawings as follows:
FIG. 1 shows the OHP, according to the invention, open and presented in a perspective view.
FIG. 2 shows the OHP, according to the invention, closed and presented in a perspective view.
FIG. 3 shows some features of the OHJP, according to the invention, viewed from FIG. 2, arrow A.
FIGS. 4 and 5 shows, according to the invention, the OHP's projection arm, with its fixing base and moving knob seen from front and top.
FIG. 6 shows some details of the invention seen from the top.
According to FIG. 1 and 2, the OHP consists of a body 2, which is supplied with an openable top part 3. Onto the body 2 is also connected a projection arm 16 with the help of a fixing base 18 and the moving knob 17. The top part of the projection arm 16 is made of a base unit 22, lens/lenses 21 and a flat mirror 20 on a holder 19. The openable top part 3 is supplied with a glass plate 8 with its holder and the acetate film rolls 4 with their holders. According to FIG. 3, the acetate film rolls are installed on axle rods 26, which are supplied from one end with rotating cylinders 5. The acetate film rolls 4, which are installed on the axle rods 26, are mounted in the openable top part 3 at opposite ends in the shaped spaces with the help of a bent spring 27 and fixing hole 28. The roll space is spaced so that when the top part 3 is in the closed position, the acetate film rolls 4 can be rotated from the rotating cylinder 5. The openable top part 3 is fixed to the body 2 with a hinge 9.
In the inner part of the body 2 is arranged four shutter screens 10-13 advantageously. The screens can be moved in a flat level with guiding rods situated in the inner side of the body 2 on all four sides so that the screens 10-13 stay, in all cases of use, inside the body 2. According to FIGS. 1 and 6, the form of operation of screens 10 and 12 is such, that they move in the same direction as the movement of the acetate film, while screens 11 and 13 move in a direction perpendicular to that of the movement of the acetate film. Each of the shutter screens 10-13 is so arranged that it can, when needed, cover all the area of the image being projected. The shutter screens 10-13 are moved with the help of the levers 14, which are easily situated in two adjacent sides of the body 2 of the OHP 1. In the inside of the body 2 is also installed a Fresnel lens 7 between the edge rims 26 and 24. The openable top part 3 is locked with the aid of the locking unit 23.
The projection arm 16 is a square section aluminum tube whose top part is bent so that the base unit 22 is always maintained in a level exactly parallel to the glass plate 8. The projection arm 16 is fixed to the body 2 with the fixing base 18. The fixing base 18 is a cylindrically shaped plastic piece into which is c
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patent: 4652101 (1987-03-01), Grunwald
patent: 4942411 (1990-07-01), Polston
patent: 4944586 (1990-07-01), Rightmyre
patent: 5052798 (1991-10-01), Mardis
Cuchlinski Jr. William A.
Dowling William C.
Educatek Oy
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