CA1168485A - Portable overhead projector and carrying case - Google Patents
Portable overhead projector and carrying caseInfo
- Publication number
- CA1168485A CA1168485A CA000400504A CA400504A CA1168485A CA 1168485 A CA1168485 A CA 1168485A CA 000400504 A CA000400504 A CA 000400504A CA 400504 A CA400504 A CA 400504A CA 1168485 A CA1168485 A CA 1168485A
- Authority
- CA
- Canada
- Prior art keywords
- post
- head
- base
- shaft
- longitudinal axis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Overhead Projectors And Projection Screens (AREA)
- Projection Apparatus (AREA)
Abstract
Abstract A portable overhead projector which may be folded into a case the size of a standard attache case. A
projection head is rotatably mounted on a post which is in turn pivotally mounted in the case. In the operating position the head and post form an angle greater than ninety degrees which allows the post to be shorter and the resulting case size to be smaller than in existing folding projectors.
projection head is rotatably mounted on a post which is in turn pivotally mounted in the case. In the operating position the head and post form an angle greater than ninety degrees which allows the post to be shorter and the resulting case size to be smaller than in existing folding projectors.
Description
259,189 CAN/DWA/JCB
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Portable Overhead Projector And Carrying Case This invention relates to an improved overhead projector, and in particular, to an improved portable overhead projector which may be readily folded into a carrying case and unfolded to place the projector in operating position with the optical elements properly aligned.
Portable overhead projectors that can be folded into a carrying case and moved about have been known in the art, and one early structure was patented in 1950 by David O. Woodbury, as U.S. patent 2,496,647. In this projector the raising of the cover 12 withdrew a head from within the base and positioned the head for projection of an image from a stage 38. The cover 12 was held in the desired open position by a pall 56 pivotally attached to the cover and engaging a toothed rack 58 on the base of the projector.
Alignment of the optical elements thus required the operator to position the cover in the proper location, placing the a~is of the projection lens 50 on the axis of the condensing lenses 37.
An additional portable overhead projector using a larger stage and supported in a carrying case which was adapted to be carried on airplanes and fit under the seat is disclosed in U.S. patent 3,167,998, issued Febrary 2, 1965 to R. H. Appeldorn et al, and assigned to the assignee o this application. This portable overhead projector utilized the cover for supporting the projection lens assem~ly 37. In this projector it was necessary ~or the lens assembly and mirror support to be removed from within the base through a cover 56 and fastened onto the cover 18 which was normally closed over the stage 25 upon which the transparencies would be placed. Thus, in setting up this projector it was necessary for the operator to move the lens assembly as a separate element from within the base and attach it to the cover. This ~fd~ 7,~:, system ~tilized more lens elements and a larger head than the projector of the present invention and the carrying case was large and bulky.
As the projection lens assembly got smaller, the carrying case got smaller, as illustrated in U.S. patent 3,209,646, issued October 5, 1965 to R. H. Appeldorn et al, and assigned to the assignee of this application. In this portable projector assembly there were a number of manual manipulatio~s t~ place the projector in position for operation. One significant feature was the fact that no parts had to be removed and repositioned to place the projector in working order or in the storage position.
One disadvantage of the projector however was the profile of the projector in the operating position provided considerable obstruction to the audience.
Other projectors which have the same defect as that of the Appeldorn et al patent 3,209,646 include the Lucas patent No. 3,285,126, issued November 15, 1966.
Prior art projectors wherein the height of the base has been substantially reduced to reduce its profile and yet provide a projector with a fairly small head are shown in U.S. patent 3,293,982, issued December 27, 1966 to R. H. Appeldorn, and assigned to the assignee of this application, and U.S. patent No. 3,459,475, issued August S, 1969 to J. W. Lucas. The later patent illustra~es an overhead projector having a removable post 15, which was held in position by a set screw 22 and onto which a projection head assembly 14 is pivoted horizon-tally 90 degrees about a hinge 19, permitting disass~mbly and stowage of the projector within a standard attache case or the like.
Thus, it can be seen that portable overhead projectors are an area of inventive endeavor.
The object has always been to have as small and compact a projector as possible, and one which may be readily assembled for use and disassembled or stowed away again for travel. Essential, however, is the positive positioning of the optical elements in the assembled position, and the separation and attachment of the projection head increases the risk of damage or misalignment of the elements. Further, separable parts do not fit as tightly and the fewer parts which must be dis-assembled and assembled makes it less likely that one of the parts is going to be left at the last conference when the projector is packaged and stowed for travel. ~lso, the fact that the projection head requires the presence of electrical power makes it necessary to have an electrical conductor connected to the head. The amount of bending which the wires have to undergo each time the projector is erected or stowed should be restricted.
The invention provides a portable overhead projector comprising a base including means defining a s-tage for supporting a transparency and an elongate projection head supporting a lens for projecting an image from the stage to a remote screen, the improvement comprising a unitary post connecting said base and said head and having a longitudinal axis, support means connected to said post at one end for rotatably mounting said post in the projector base for pivotal movement of said post about journals spaced wider than said pos~ to move said post about an axis between a position generally parallel to the base and a position at an angle to the base, and a shaft rigidly attached to said post at the opposite end thereof and extending normal to said longitu-dinal axis of said post, said shaft pivotally supporting said head, said head being rotatably mounted on said shaft for movement there-about from a position with the head generally parallel to the longitudinal axis of said post to a position with said head at an angle to said post; wherein said post maintains said shaft in fixed spaced relationship to said support means in and between said position generally parallel to the base and said position at an angle to the base.
In the disclosed embodiment of the present invention - the overhead projector is readily portable in a case which corre-sponds essentially in overall appearance and size to an attache case. The parts of the projector fold into the carr~ing case and ~he cover for the case is reversible to provide in the carrying position a cover, and in the operating position, the stage for supporting the transparency.
The projector utilizes the case as a base and includes means defining a stage for supporting the transparency and a pro-jection head for supporting the lens for projecting an image from the stage to a remote screen. Preferably, the post has a pair of parallel shafts rigidly connected at opposite ends thereof which shafts extend from the post normal to the longitudinal axis of the post. The first shaft provides spaced journal points spaced a distance greater than the width of the post to give it stability and is journalled in the base to move the post pivotally from a position generally parallel to the ~ase to a position at an angle to the ~ase, and the second shaft rigidly connected to the post has the head rotatably -3a-., , supported thereon. The head is rotatably mounted on the second shaft for pivoted movement about the axis of the shaft from a position generally parallel to the longitudinal axis of the post to a position at an angle to the axis of the post in the operating position. Locks are provided for locking the post in the angular position and for locking the head in the parallel or angular position with respect to the post. The head has a long slender profile which makes it easy to stow within the base. In the operating position, the head is positioned at an angle greater than 100 degrees with respect to the longitudinal axis of the post to dispose the projection lens at the proper height above the stage. This reduces the need for an extended length post which would result in a lengthening 15 of the carrying case, which case is similar in size and shape to an attache case having a handle thereon for supporting the projector.
The invention will be hereinafter described in greater detail with reference to the accompanying drawing, 20 wherein:
Figure 1 is a perspective view of the overhead projector of the present invention stowed in its carrying case;
Figure 2 is a view of the overhead projector of the present invention partially opened for use;
Figure 3 is a perspective view of the projector with the parts disposed in operating position;
Figure 4 is a fragmentary longitudinal sectional view of the projector of the present invention with 30 portions broken away to show the portions positioned interiorly which portions lock the post and head in their respective angular positions with respect to the base, Figure 5 is a transverse-sectional view further showing details of -the lock mechanism for maintaining the elements of the projector in their operating position;
Figure 6 is an exploded perspective view of the parts of the lock for the projection head;
Figure 7 is a perspective view of the movable cam member of the lock; and Figure 8 is a longitudinal sectional view of the projection head.
The overhead projector is adapted to project images from a projection slate or stage which is 285 X 285 mm onto a screen, between 1.4 meters and 2.2 meters from the projector, to provide an image thereon of between 1.3 X
13 meters up to 2 X 2 meters. The lens utilized on such projector could constitute a single projection lens having a focal length of 293 mm. The projector 10 is packaged in a carrying case resembling an attache case which has a carrying handle 11 on one side 12 which is opposite a bottom side 13, when in the carrying position, provided with suitable protective feet. The end 14 of the carrying case has a sliding door 15 covering a switch 16. In the operating position the projector is placed on one side having suitable small supporting feet and the top 16 has a removable cover 20 on one side of which is the projection slate 21. The carrying case has overall dimensions of 445 mm by 318 mm by 108 mm.
The cover 20 is retained in place by two latches 22. The projector is readily opened in~o operating ; position by first removing the cover 20 as will hereinafter be descrlbed.
Removal of the cover 20 exposes a flexible protective sheet 24 which is secured along one edge to the inside of the wall 13. The projection head 25 is then visible in its stowed position in a recess 26 wtthin the case. The projection head 25 is pivotally mounted on a novel support element including a post 28 which is connected to the base of the projector, formed by the case, by means of a first shaft 29 which is rigidly fixed to the post 28 and which has, at its other end, a second shaft 30 rigidly connected to the post about which the head 25 is pivotally mounted, as will hereinafter be ~! described. The shaft 29 can be replaced by a hollow shaft or bushing projecting through the post. It is important S that the shaft provide support points spaced a distance greater than the width of the post 28 to provide stability against lateral movement.
In raising the projection head from its stowed position, which is generally parallel to the longitudinal 10 axis of the base, a latch 32 is released from a plate 33 on the post 28, and the post and the head 25 are pivoted to a raised angular position with respect to the base through an angle of 90 degrees, as indicated by the anyle in Figure 4. The post is then locked in its 15 raised angular position and the head 25 is pivoted about the shaft 30 through an angle of between 105 and 110 degrees, and as illustrated, through an angle of 108 degrees to position the longitudinal axis 35 of the projection head at an angle of 108 degrees with respect to 20 the longitudinal axis of the post 2~, as indicated by the line 36.
The angular position of the projection head places the projection lens 40 above the stage or projec-tion slate 21 by a distance sufficient to receive the 25 projected image of a transparency on the slate 21. The image is folded by a mirror 41 toward the remote screen.
The latch 32 comprises a lever 42 pivoted about a pin 43, and urged by a spring 44 to place a pall 45 in position over the plate 33 to capture the same. ~he pall 30 45 has a bevelled surface on the edge opposite the pall such that as the projection head and post are pivoted from the angular position to the position generally parallel with the base, the plate 33 cams the lever 42 toward the end 14 of the hase until the pall 45 fits over the plate 35 33, securing the post and the head in stowed positio~ in the recess 26.
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AS the latch 32 is released, the head and the post may be pivoted toward the raised position by rotating shaft 27 in two spaced journals defined by two rigid walls 47 and 48 extending from the rear wall of the case~
The post 28 is latched in the vertical position, when the predetermined angular position is reached, by means of a spring-biased pall 50 pivotally mounted about a pin 51 extending from the wall 47. The pall 50 has a ramp 52 which is engaged by the end 53 of the post 28, causing the pall 50 to pivot against the bias of a spring 55 toward the bottom of the case until such time as the post slides by a shoulder 56 on the pall. The post is then retained in the central portion of the pall between two spaced shoulders 56 and 57. The pin 58, which extends from the pall through the wall 47, is attached to one end of the spring 551 and the other end of the spring 55 is positioned thereabove and anchored to a fixed pin 59.
Pall 50 is released from the end 53 of the post
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Portable Overhead Projector And Carrying Case This invention relates to an improved overhead projector, and in particular, to an improved portable overhead projector which may be readily folded into a carrying case and unfolded to place the projector in operating position with the optical elements properly aligned.
Portable overhead projectors that can be folded into a carrying case and moved about have been known in the art, and one early structure was patented in 1950 by David O. Woodbury, as U.S. patent 2,496,647. In this projector the raising of the cover 12 withdrew a head from within the base and positioned the head for projection of an image from a stage 38. The cover 12 was held in the desired open position by a pall 56 pivotally attached to the cover and engaging a toothed rack 58 on the base of the projector.
Alignment of the optical elements thus required the operator to position the cover in the proper location, placing the a~is of the projection lens 50 on the axis of the condensing lenses 37.
An additional portable overhead projector using a larger stage and supported in a carrying case which was adapted to be carried on airplanes and fit under the seat is disclosed in U.S. patent 3,167,998, issued Febrary 2, 1965 to R. H. Appeldorn et al, and assigned to the assignee o this application. This portable overhead projector utilized the cover for supporting the projection lens assem~ly 37. In this projector it was necessary ~or the lens assembly and mirror support to be removed from within the base through a cover 56 and fastened onto the cover 18 which was normally closed over the stage 25 upon which the transparencies would be placed. Thus, in setting up this projector it was necessary for the operator to move the lens assembly as a separate element from within the base and attach it to the cover. This ~fd~ 7,~:, system ~tilized more lens elements and a larger head than the projector of the present invention and the carrying case was large and bulky.
As the projection lens assembly got smaller, the carrying case got smaller, as illustrated in U.S. patent 3,209,646, issued October 5, 1965 to R. H. Appeldorn et al, and assigned to the assignee of this application. In this portable projector assembly there were a number of manual manipulatio~s t~ place the projector in position for operation. One significant feature was the fact that no parts had to be removed and repositioned to place the projector in working order or in the storage position.
One disadvantage of the projector however was the profile of the projector in the operating position provided considerable obstruction to the audience.
Other projectors which have the same defect as that of the Appeldorn et al patent 3,209,646 include the Lucas patent No. 3,285,126, issued November 15, 1966.
Prior art projectors wherein the height of the base has been substantially reduced to reduce its profile and yet provide a projector with a fairly small head are shown in U.S. patent 3,293,982, issued December 27, 1966 to R. H. Appeldorn, and assigned to the assignee of this application, and U.S. patent No. 3,459,475, issued August S, 1969 to J. W. Lucas. The later patent illustra~es an overhead projector having a removable post 15, which was held in position by a set screw 22 and onto which a projection head assembly 14 is pivoted horizon-tally 90 degrees about a hinge 19, permitting disass~mbly and stowage of the projector within a standard attache case or the like.
Thus, it can be seen that portable overhead projectors are an area of inventive endeavor.
The object has always been to have as small and compact a projector as possible, and one which may be readily assembled for use and disassembled or stowed away again for travel. Essential, however, is the positive positioning of the optical elements in the assembled position, and the separation and attachment of the projection head increases the risk of damage or misalignment of the elements. Further, separable parts do not fit as tightly and the fewer parts which must be dis-assembled and assembled makes it less likely that one of the parts is going to be left at the last conference when the projector is packaged and stowed for travel. ~lso, the fact that the projection head requires the presence of electrical power makes it necessary to have an electrical conductor connected to the head. The amount of bending which the wires have to undergo each time the projector is erected or stowed should be restricted.
The invention provides a portable overhead projector comprising a base including means defining a s-tage for supporting a transparency and an elongate projection head supporting a lens for projecting an image from the stage to a remote screen, the improvement comprising a unitary post connecting said base and said head and having a longitudinal axis, support means connected to said post at one end for rotatably mounting said post in the projector base for pivotal movement of said post about journals spaced wider than said pos~ to move said post about an axis between a position generally parallel to the base and a position at an angle to the base, and a shaft rigidly attached to said post at the opposite end thereof and extending normal to said longitu-dinal axis of said post, said shaft pivotally supporting said head, said head being rotatably mounted on said shaft for movement there-about from a position with the head generally parallel to the longitudinal axis of said post to a position with said head at an angle to said post; wherein said post maintains said shaft in fixed spaced relationship to said support means in and between said position generally parallel to the base and said position at an angle to the base.
In the disclosed embodiment of the present invention - the overhead projector is readily portable in a case which corre-sponds essentially in overall appearance and size to an attache case. The parts of the projector fold into the carr~ing case and ~he cover for the case is reversible to provide in the carrying position a cover, and in the operating position, the stage for supporting the transparency.
The projector utilizes the case as a base and includes means defining a stage for supporting the transparency and a pro-jection head for supporting the lens for projecting an image from the stage to a remote screen. Preferably, the post has a pair of parallel shafts rigidly connected at opposite ends thereof which shafts extend from the post normal to the longitudinal axis of the post. The first shaft provides spaced journal points spaced a distance greater than the width of the post to give it stability and is journalled in the base to move the post pivotally from a position generally parallel to the ~ase to a position at an angle to the ~ase, and the second shaft rigidly connected to the post has the head rotatably -3a-., , supported thereon. The head is rotatably mounted on the second shaft for pivoted movement about the axis of the shaft from a position generally parallel to the longitudinal axis of the post to a position at an angle to the axis of the post in the operating position. Locks are provided for locking the post in the angular position and for locking the head in the parallel or angular position with respect to the post. The head has a long slender profile which makes it easy to stow within the base. In the operating position, the head is positioned at an angle greater than 100 degrees with respect to the longitudinal axis of the post to dispose the projection lens at the proper height above the stage. This reduces the need for an extended length post which would result in a lengthening 15 of the carrying case, which case is similar in size and shape to an attache case having a handle thereon for supporting the projector.
The invention will be hereinafter described in greater detail with reference to the accompanying drawing, 20 wherein:
Figure 1 is a perspective view of the overhead projector of the present invention stowed in its carrying case;
Figure 2 is a view of the overhead projector of the present invention partially opened for use;
Figure 3 is a perspective view of the projector with the parts disposed in operating position;
Figure 4 is a fragmentary longitudinal sectional view of the projector of the present invention with 30 portions broken away to show the portions positioned interiorly which portions lock the post and head in their respective angular positions with respect to the base, Figure 5 is a transverse-sectional view further showing details of -the lock mechanism for maintaining the elements of the projector in their operating position;
Figure 6 is an exploded perspective view of the parts of the lock for the projection head;
Figure 7 is a perspective view of the movable cam member of the lock; and Figure 8 is a longitudinal sectional view of the projection head.
The overhead projector is adapted to project images from a projection slate or stage which is 285 X 285 mm onto a screen, between 1.4 meters and 2.2 meters from the projector, to provide an image thereon of between 1.3 X
13 meters up to 2 X 2 meters. The lens utilized on such projector could constitute a single projection lens having a focal length of 293 mm. The projector 10 is packaged in a carrying case resembling an attache case which has a carrying handle 11 on one side 12 which is opposite a bottom side 13, when in the carrying position, provided with suitable protective feet. The end 14 of the carrying case has a sliding door 15 covering a switch 16. In the operating position the projector is placed on one side having suitable small supporting feet and the top 16 has a removable cover 20 on one side of which is the projection slate 21. The carrying case has overall dimensions of 445 mm by 318 mm by 108 mm.
The cover 20 is retained in place by two latches 22. The projector is readily opened in~o operating ; position by first removing the cover 20 as will hereinafter be descrlbed.
Removal of the cover 20 exposes a flexible protective sheet 24 which is secured along one edge to the inside of the wall 13. The projection head 25 is then visible in its stowed position in a recess 26 wtthin the case. The projection head 25 is pivotally mounted on a novel support element including a post 28 which is connected to the base of the projector, formed by the case, by means of a first shaft 29 which is rigidly fixed to the post 28 and which has, at its other end, a second shaft 30 rigidly connected to the post about which the head 25 is pivotally mounted, as will hereinafter be ~! described. The shaft 29 can be replaced by a hollow shaft or bushing projecting through the post. It is important S that the shaft provide support points spaced a distance greater than the width of the post 28 to provide stability against lateral movement.
In raising the projection head from its stowed position, which is generally parallel to the longitudinal 10 axis of the base, a latch 32 is released from a plate 33 on the post 28, and the post and the head 25 are pivoted to a raised angular position with respect to the base through an angle of 90 degrees, as indicated by the anyle in Figure 4. The post is then locked in its 15 raised angular position and the head 25 is pivoted about the shaft 30 through an angle of between 105 and 110 degrees, and as illustrated, through an angle of 108 degrees to position the longitudinal axis 35 of the projection head at an angle of 108 degrees with respect to 20 the longitudinal axis of the post 2~, as indicated by the line 36.
The angular position of the projection head places the projection lens 40 above the stage or projec-tion slate 21 by a distance sufficient to receive the 25 projected image of a transparency on the slate 21. The image is folded by a mirror 41 toward the remote screen.
The latch 32 comprises a lever 42 pivoted about a pin 43, and urged by a spring 44 to place a pall 45 in position over the plate 33 to capture the same. ~he pall 30 45 has a bevelled surface on the edge opposite the pall such that as the projection head and post are pivoted from the angular position to the position generally parallel with the base, the plate 33 cams the lever 42 toward the end 14 of the hase until the pall 45 fits over the plate 35 33, securing the post and the head in stowed positio~ in the recess 26.
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AS the latch 32 is released, the head and the post may be pivoted toward the raised position by rotating shaft 27 in two spaced journals defined by two rigid walls 47 and 48 extending from the rear wall of the case~
The post 28 is latched in the vertical position, when the predetermined angular position is reached, by means of a spring-biased pall 50 pivotally mounted about a pin 51 extending from the wall 47. The pall 50 has a ramp 52 which is engaged by the end 53 of the post 28, causing the pall 50 to pivot against the bias of a spring 55 toward the bottom of the case until such time as the post slides by a shoulder 56 on the pall. The post is then retained in the central portion of the pall between two spaced shoulders 56 and 57. The pin 58, which extends from the pall through the wall 47, is attached to one end of the spring 551 and the other end of the spring 55 is positioned thereabove and anchored to a fixed pin 59.
Pall 50 is released from the end 53 of the post
2~ by depressing a handle 60 which extends through a wall 61 positioned forward of the rear wall o~ the case and defining one wall of the recess 26. The handle 60 extends through the wall and extends rearwardly over the top of the pin 58 to a pivot pin 62 mounted in the wall 48. Thus it is readily seen that depressing the handle 60 within the recess 26 will move the pin 58 downward against the bias of the spring 55, releasing shoulder 56 from the end
3 of the post 28 to allow the same to be returned to lts stowed position.
In moving from the upright position to the stowed position a spring 70 is utilized to re~ard the free rotation of the shaft 29 such that the head will not fall freely into the recess 26 but must be moved by the opera-tor against the force of this spring retarding device 70.
The spring 70 is secured at one end to the wall 48 and to the shaft 29 adjacent the opposite end.
When the post 28 has been raised to its vertical po~ition, as shown in Figure 4, the head 25 is then pivoted about the shaft 30 through the angle to its predetermined ~ixed position. This movement is accomplished by releasing a catch which holds the head in the position generally parallel to the longitudinal axis of the post 28, permitting the head to be rotated. The latch again locks the head in position for operatioh at an angle of 108 degrees with respect to the longitudinal axis of the post 28. This catch is also illustrated in Figures
In moving from the upright position to the stowed position a spring 70 is utilized to re~ard the free rotation of the shaft 29 such that the head will not fall freely into the recess 26 but must be moved by the opera-tor against the force of this spring retarding device 70.
The spring 70 is secured at one end to the wall 48 and to the shaft 29 adjacent the opposite end.
When the post 28 has been raised to its vertical po~ition, as shown in Figure 4, the head 25 is then pivoted about the shaft 30 through the angle to its predetermined ~ixed position. This movement is accomplished by releasing a catch which holds the head in the position generally parallel to the longitudinal axis of the post 28, permitting the head to be rotated. The latch again locks the head in position for operatioh at an angle of 108 degrees with respect to the longitudinal axis of the post 28. This catch is also illustrated in Figures
4 through 7, and comprises a fixed thumb fulcrum 71 and a movable button 72, which is fixed to an arm 74, pivoted on ~in 75, and to a rotatable cam 76 by a link 77. The button is biased away from fulcrum 71 by a spring 78.
Movement o~ button 72 releases a lock and allows movement of the head 25~ The locking member 79 releases a lock and allows movement of the head 25. The locking member 79 is biased by a compression spring 80 toward and into engage-ment with a hole on a locking plate 81 fixed to the head 25. The locking member 79 slides axially on the portion of shaft 30 which is square in cross-section and has a lug 82 on a radial arm which engages one of two spaced holes 83 in the plate 81. Upon movement of the arm 74 by the button 72 the cam 76 is rotated causing three axially projecting ramps or cam surfaces 84 to follow cam surfaces 85 on the plate 81 causing axial movement of locking member 79 to lift the lug 82 from a hole 83, depending on the position of the head 25. The holes 83 are spaced 108 degrees about the axis of opening 86 to position the head parallel or at an angle to the longitudinal axis of the post 28. A threaded nut 87 on the shaft 30 positions the head 25 laterally of the base to the desired position against the bias of compression spring 80.
Pivotal movement of the head may be frictionally retarded by a torsion spring or other suitable device not shown. This braking force can be considerably less than the frictional force retarding movement of the head and the post toward the recess 26 during rotation of shaft 29 about the journals for said shaft 29 in that direction.
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_9_ :' The projection head 25 ~or the overhead pro~ector 10 comprises a housing 89 which is fixed to the frame 90 of ~he head and provides a decorative facade. A
projection lamp 91 is mounted in the rear portion of the
Movement o~ button 72 releases a lock and allows movement of the head 25~ The locking member 79 releases a lock and allows movement of the head 25. The locking member 79 is biased by a compression spring 80 toward and into engage-ment with a hole on a locking plate 81 fixed to the head 25. The locking member 79 slides axially on the portion of shaft 30 which is square in cross-section and has a lug 82 on a radial arm which engages one of two spaced holes 83 in the plate 81. Upon movement of the arm 74 by the button 72 the cam 76 is rotated causing three axially projecting ramps or cam surfaces 84 to follow cam surfaces 85 on the plate 81 causing axial movement of locking member 79 to lift the lug 82 from a hole 83, depending on the position of the head 25. The holes 83 are spaced 108 degrees about the axis of opening 86 to position the head parallel or at an angle to the longitudinal axis of the post 28. A threaded nut 87 on the shaft 30 positions the head 25 laterally of the base to the desired position against the bias of compression spring 80.
Pivotal movement of the head may be frictionally retarded by a torsion spring or other suitable device not shown. This braking force can be considerably less than the frictional force retarding movement of the head and the post toward the recess 26 during rotation of shaft 29 about the journals for said shaft 29 in that direction.
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_9_ :' The projection head 25 ~or the overhead pro~ector 10 comprises a housing 89 which is fixed to the frame 90 of ~he head and provides a decorative facade. A
projection lamp 91 is mounted in the rear portion of the
5 head. Light from this lamp is directed by a reflactor which is part of the projection lamp towards a planar mirror 92 which directs the light in a cone toward the projection slate 21. The light path from the lamp to the slate 21 is as long as from the slate to the lens 40.
10 Projection slate 21 has a fresnel mirror which focusses the light from the lamp 91 into the lens 40 to be then directed by mirror 41 toward the remote screen. The lens 40 and mirror 41 are mounted in a housing 95 which are movable with respect to the frame 90 of the head to afford 15 focussing of the projected image on the remote screen.
As shown in Figure 8, the housing 95 for the mirror 41 and lens 40 includes a pivotal supporting member 96 Eor the mirror 41 which permits the mirror 41 to be pivoted about the axis 97 to raise or lower the image on 20 the remote screen. The mirror and lens bousing ~5 is positioned for vertical movement and has a slide on one side and a rack 98 which moves in a guide 99 on the other.
The rack 98 and housing 95 are movable with respect to a fixed rack 100 by rotation of a movable pinion 101 secured 25 to a han~le 102 projecting from the sidewall of the pro-jection head ( see Figs. 2 and 3). Rotation of this handle 102 causes relative movement of the racX 98 with respect to the fixed rack 100, causing motion of the housing 95 and repositioning of the lens 40 with respect to the 30 projection slate 21.
Having thus described the present invention with respect to the preferred embodiment it will be understood ; that other modifications may be made herein without departing from the spirit and scope of the invention as 35 defined by the appended claims.
10 Projection slate 21 has a fresnel mirror which focusses the light from the lamp 91 into the lens 40 to be then directed by mirror 41 toward the remote screen. The lens 40 and mirror 41 are mounted in a housing 95 which are movable with respect to the frame 90 of the head to afford 15 focussing of the projected image on the remote screen.
As shown in Figure 8, the housing 95 for the mirror 41 and lens 40 includes a pivotal supporting member 96 Eor the mirror 41 which permits the mirror 41 to be pivoted about the axis 97 to raise or lower the image on 20 the remote screen. The mirror and lens bousing ~5 is positioned for vertical movement and has a slide on one side and a rack 98 which moves in a guide 99 on the other.
The rack 98 and housing 95 are movable with respect to a fixed rack 100 by rotation of a movable pinion 101 secured 25 to a han~le 102 projecting from the sidewall of the pro-jection head ( see Figs. 2 and 3). Rotation of this handle 102 causes relative movement of the racX 98 with respect to the fixed rack 100, causing motion of the housing 95 and repositioning of the lens 40 with respect to the 30 projection slate 21.
Having thus described the present invention with respect to the preferred embodiment it will be understood ; that other modifications may be made herein without departing from the spirit and scope of the invention as 35 defined by the appended claims.
Claims (9)
1. A portable overhead projector comprising a base including means defining a stage for supporting a transparency and an elongate projection head supporting a lens for projecting an image from the stage to a remote screen, the improvement comprising a unitary post connecting said base and said head and having a longitudinal axis, support means connected to said post at one end for rotatably mounting said post in the projector base for pivotal movement of said post about journals spaced wider than said post to move said post about an axis between a position generally parallel to the base and a position at an angle to the base, and a shaft rigidly attached to said post at the opposite end thereof and extending normal to said longitudinal axis of said post, said shaft pivotally supporting said head, said head being rotatably mounted on said shaft for movement thereabout from a position with the head generally parallel to the longitudinal axis of said post to a position with said head at an angle to said post;
wherein said post maintains said shaft in fixed spaced relationship to said support means in and between said position generally parallel to the base and said position at an angle to the base.
wherein said post maintains said shaft in fixed spaced relationship to said support means in and between said position generally parallel to the base and said position at an angle to the base.
2. An overhead projector as defined in claim 1 wherein a locking mechanism is connected to said head to lock said head to said shaft in a predetermined angular position to said longitudinal axis of said post.
3. A portable overhead projector comprising a base including means defining a stage for supporting a transparency and an elongate projection head supporting a lens for projecting an image from the stage to a remote screen, the improvement comprising a post connecting said base and said head and having a longitudinal axis, support means connected to said post at one end for rotatably mounting said post in the projector base for pivotal movement of said post about journals spaced wider than said post to move said post about an axis between a position generally parallel to the base and a position at an angle to the base, a shaft rigidly attached to said post at the opposite end thereof and extending normal to said longitudinal axis of said post, said shaft pivotally supporting said head, said head being rotatably mounted on said shaft for movement thereabout from a position with the head generally parallel to the longitudinal axis of said post to a position with said head at an angle to said post, and a locking mechanism supported by said base to lock said post in a predetermined position with respect to said base when said post is in said angular position with respect to said base, and spring means for retarding the pivotal movement of said post and rotation of said post and support means from said angular position to said position generally parallel to said base.
4. An overhead projector according to claim 3 wherein said angular relationship of said head and the longitudinal axis of said post is between 105 and 110 degrees.
5. An overhead projector according to claim 4 wherein the longitudinal axis of said head forms an angle of 108 degrees with the longitudinal axis of said post.
6. An overhead projector according to claim 3 wherein said head is pivoted about said shaft to a position generally parallel to said longitudinal axis, and said head and said post pivot with and about the axis of said support means to position said head in said base at a level below said means defining a stage whereby said head is rotated from said storage position to an operating position through an arc of 198 degrees about two axes.
7. An overhead projector according to claim 3 or 6 wherein said shaft is parallel to the axis of said support means and extends from said post in the same direction from said post as said support means.
8. An overhead projector according to claim 5 wherein said shaft is parallel to the axis of said support means and extends from said post in the same direction from said post as said support means.
9. An overhead projector according to claim 3 wherein said support means is a shaft fixed rigidly -to said post and extending to one side thereof parallel to said first mentioned shaft.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US25918981A | 1981-04-30 | 1981-04-30 | |
| US259,189 | 1981-04-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168485A true CA1168485A (en) | 1984-06-05 |
Family
ID=22983905
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000400504A Expired CA1168485A (en) | 1981-04-30 | 1982-04-06 | Portable overhead projector and carrying case |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU549673B2 (en) |
| CA (1) | CA1168485A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4978218A (en) * | 1990-03-01 | 1990-12-18 | Minnesota Mining And Manufacturing Company | Folding arm for overhead projector |
| US5428416A (en) * | 1994-05-13 | 1995-06-27 | Minnesota Mining And Manufacturing Company | Overhead projector support leg mechanism |
-
1982
- 1982-04-06 CA CA000400504A patent/CA1168485A/en not_active Expired
- 1982-04-29 AU AU83126/82A patent/AU549673B2/en not_active Ceased
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4978218A (en) * | 1990-03-01 | 1990-12-18 | Minnesota Mining And Manufacturing Company | Folding arm for overhead projector |
| US5428416A (en) * | 1994-05-13 | 1995-06-27 | Minnesota Mining And Manufacturing Company | Overhead projector support leg mechanism |
Also Published As
| Publication number | Publication date |
|---|---|
| AU549673B2 (en) | 1986-02-06 |
| AU8312682A (en) | 1982-11-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |