Removable Door For Instrument Casing

Abstract

detachable pivot connection is provided for readily mounting a cover on an instrument casing. A spring and a cam arrangement is provided for maintaining the pivotal connection. In addition, the spring and cam arrangement function to maintain the cover closed unless it is rotated beyond a preset position in which case the cover is automatically rotated to an open position.

Description

BACKGROUND OF THE INVENTION

The invention pertains to covers for instrument casings and the like, and more particularly to readily detachable covers that provide a resilient force for maintaining the cover closed, or maintaining the cover open once it is rotated beyond a preset position.

Covers for instrument cases generally include a window for viewing recordings or indicators to provide information pertaining to the instrument operation. Quite often, the covers are required to be opened so that adjustments can be made, or the reservoirs for ink be replenished. Because of the frequent opening and closing of the cover over the long life of the instruments, the windows on the covers often become scratched or dirty. In some cases, the corners on the doors break or otherwise become warped and do not stay in position. As a result, it is highly desirable that such covers can be readily removed and replaced by new covers. In addition to the foregoing, it is also highly desirable that the cover can be readily opened and when opened continue to remain open without the need for holding the cover open by hand.

A readily removable door for an instrument casing is disclosed in the U.S. Pat. No. 3,525,177 issued on Aug. 25, 1970 to C. F. Robinson. The arrangement disclosed in the patent provides a detachable door that is required to be rotated to a preset angle for the removal thereof. In addition to the foregoing, if the door is to be opened and remain open, the door is required to be opened to the horizontal position and then slid into the casing wherein the casing would hold the door open. Although such arrangement does satisfy its purposes, the requirement to rotate the door to a horizontal position and then push the door into the casing is rather cumbersome particularly if the person adjusting the instrument is in a hurry. It would be highly desirable, if the cover could be provided for an instrument casing in which the observer need merely open the cover beyond a preset angle and release the cover wherein the cover would remain open. It would also be highly desirable, if the cover could be closed by merely pushing the cover downward and releasing and allowing the cover to close itself.

It is therefore an object of this invention to provide a new and improved cover for instrument casing and the like.

It is also an object of this invention to provide a new and improved cover for instrument casings that is readily detachable.

It is another object of this invention to provide a new and improved cover for instrument casings that is readily detachable and provides a detent action for opening and closing the cover.

BRIEF DESCRIPTION OF THE INVENTION

A planar shaped cover for a instrument housing having a planar side, wherein pivot means are provided on the housing and on the cover for detachably mating the housing and cover together to provide a pivotal connection for rotating the cover about an axis of rotation. Resilient means urge the housing and cover pivot means together and also urge against a cam arrangement, wherein when the cover is rotated to less than a preset angle from a closed position, the cam and resilient means urge the cover to the closed position. On the other hand, when the cover is rotated to an angle greater than the preset position, the cam and resilient means urge the cover in a direction away from the housing side to an open position.

The pivot means can, for example, include a pair of pins and a pair of sockets. The pins can be included on the instrument housing and the sockets on the cover, or vice versa.

The camming arrangement can, for example, include a pair of cams on each of the pair of pins, each urging against the resilient means. A surface of the cam and the axis of rotation define an obtuse triangle wherein the longest side of the triangle extends through the axis of rotation and defines balance position for the cover. When the cover is rotated from the closed position to an angle less than that defined by the balance position, the cam and the resilient means urge the cover back to the closed position. When the cover is rotated beyond the balanced position, the cam and resilient means urge the cover to the open position.

When in the closed position, the cam and resilient means apply a continuous force to the cover to maintain the cover closed against a stop. In the case of the open position, the cam can provide a stop for the rotation, or a separate mechanical stop can be provided therefore.

The combination of the pivot means, resilient means, and the cam means provides a relatively inexpensive detachable cover that can be set into position by merely placing the pins adjacent the socket and the resilient means and applying a pressure to the cover to open the spring and allow the pins to slip into the sockets. Once the cover is inserted into place, the cover can be opened by merely flipping up the cover beyond the preset angle and the cover will continue to rotate under the force of the cam and resilient means to the open position. If is thereafter desired to closed the cover, the cover is merely pushed down beyond the balance position and the cover will continue to rotate and snap into the closed position.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a front view of a recorder including the cover and casing assembly of the invention.

FIG. 2 is a front view of the recorder of FIG. 1 with the cover removed.

FIG. 3 is a top view of the front panel or face of the recorder of FIG. 2.

FIG. 4 is the front view of the cover of FIG. 1.

FIG. 5 is a rear view of the cover of FIG. 4.

FIG. 6 is a side view of the cover of FIG. 4.

FIG. 7 is a sectional view of the cover of FIG. 5 taken along lines 7--7.

FIG. 8 is a sectional view of the face of the instrument of FIG. 1 taken along lines 8--8 to illustrate the cover in the closed position, and also a partial view of the open position in phantom.

FIG. 9 is an enlarged view of the pivot socket and leaf spring mounted in the top of the cover.

FIG. 10 is an enlarged side view of the pivot pin and cam arrangement mounted in the instrument casing.

FIG. 11 illustrates the rotational action of the cover and the position of the leaf spring in the closed position, and also in the open position in phantom.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated in FIG. 1, a cover 10 is mounted on the front of an instrument casing 12. The instrument for purposes of illustration is a three pen recorder, however, it should be understood that the readily detachable cover arrangement of the invention is applicable to any type of instrument or casing wherein it is highly desirable to easily replace such covers, and where it is desirable to open the cover by merely flicking the cover up wherein the cover automatically rotates to a preset open position, and wherein it is desirable to close the cover by merely flicking the cover down and the cover automatically rotates down to a closed position.

The cover 10 includes a handle 14 for opening and shutting the cover 10 and a transparent section 16 for viewing the contents within the housing. Pivot means and resilient means are mounted on the top rear side of the cover as illustrated in FIGS. 5, 6, and 7. The pivot means include a pair of sockets 18 disposed adjacent the top corners of the cover 10 and a leaf spring 20 that is secured to the cover by a pair of screws 22. The ends 24 of the leaf spring 20 extend beyond the sockets 18 and include a bend therein that extends towards the the cover front.

The sockets 18 are positioned to mate with the pair of pins 26 mounted on the instrument housing adjacent opposite top corners thereof. The pins 26 lie on a common axis 28, which is the axis of rotation for the cover 12. A separate cam 30 is mounted on the portion of each of the pins 26 adjacent the instrument housing. The combination of the pins 26, cams 30, sockets 18, and the leaf spring 20 provides a readily detachable cover for the instrument casing. The cover is mounted on the instrument casing by positioning the cover 12 so that the bottom side 32 of the leaf spring 20 projects above the pins 26 and the cams 30 and wherein the sockets 18 are adjacent the pins 26. The alignment of the sockets 18 and the pins 26 is aided by the sides 34 of the casing housing. The cover 10 is snapped into place by applying a pressure on the top of the cover so that the ends 24 of the spring 20 are forced away from the front of the cover allowing the pins 26 to snap into the sockets 18. Thereafter, the force of the ends 24 of the spring 20 maintain the pivotal connection. The shape of the socket 18 is such (as illustrated in FIG. 9) that the urging forces of the spring 20 maintains the socket connection mated as the cover is rotated.

The cams 30 (FIG. 10) have the shape of a tetrahedron, wherein two of the cam surfaces 40 and 42 lie in converging planes that are transverse to the plane 44 of the instrument housing. The other two surfaces 46 and 48 are parallel to each other and parallel to the top 50 of the instrument housing. The arrangement of the cams is such that the surface 48 and the axis of rotation 28 define an obtuse triangle (a triangle having unequal sides) wherein the longest side 52 extends from the axis of rotation through the junction of the cam surfaces 40 and 48. The triangle side 52 defines a balanced position that determines the direction in which the cover will be rotated by the combined action of the cams 30 and the leaf spring 20.

Referring now to FIG. 11, the cover 12 and the leaf spring 20 are illustrated in hold lines in the closed position while the cover and the leaf spring are illustrated in phantom in the open position. As the cover is rotated about the axis 28, the leaf spring 20 also rotates about the axis but its position from the axis varies as the function of the cam 30. The angle A defines the angle through which the leaf spring 30 can be rotated from the closed position (wherein the cover is parallel to the housing face) to the balance position designated by the line 52, wherein the combination of the cam 30 and the spring 20 will rotate the cover back to the closed position. On the other hand, if the cover 12 is rotated from the closed position over a angle greater than A (past the line 52), the action of the cam 30 and the spring 20 continue to rotate the cover 21 until the cover 12 reaches the open position. When the cover 12 has rotated to a point wherein the leaf spring reaches the position as illustrated in phantom in FIG. 11, the forces of the cams 30 on the leaf spring 20 urge on equal and opposite halves of the leaf spring thereby defining a balance condition, i.e., the open position before the cover. The combination of the cam 30 and the spring 20 provides a lever arrangement wherein the fulcrum of the lever rotates about the cam with the cover 12. For example, when the cover 12 is in the closed position, the fulcrum is located at the point 58 wherein a force is applied by the cam 30 to the spring 20 at point 60 resulting in a continuous resilient force to maintain the cover in a closed position. As the cover 12 is rotated, the fulcrum point continues to rotate about the axis of rotation 28. When the fulcrum reaches the point 60, all the force on spring 20 by the cam 30 are concentrated at the fulcrum resulting in a balanced condition and no rotation. When the cover 12 is rotated beyond the angle A, the fulcrum is located beyond the point 60 and the cam applies a force to the spring 20 in a direction to continue the rotation towards the open position. When the fulcrum 58 reaches the line 62, equal and opposite forces are applied to both sides of the fulcrum resulting in the balanced open condition. The rotational effect is provided by the combination of the spring 20 and the cams 30 to the open and the closed positions since the longest leg 52 of the triangle (defined by the surface 48 and the axis of rotation 28) is located at the balance point so that once the cover is rotated beyond the balance point, an unbalance situation occurs until the cover 12 is rotated to its closed or open positions.

Although the cam 30 is illustrated in FIGS. 10 and 11 in the form of a tetrahedron, it could be understood that the cam can have the form of the triangle defined by the surface 48 the axis 28 and lines 51 and 52. However, in such case, a stop or limit 64 (illustrated in phantom in FIG. 10) would be required to define the open condition. In addition to the foregoing, it should be understood that although the combination of the cover and housing including the invention has been described and illustrated with the cams 30 and the pins 28 mounted in the instrument housing, and with the socket 18 and the spring 20 mounted on the cover, the arrangement can be easily reversed wherein, the socket and the spring can be mounted on the housing while the cam and the pin can be mounted on the cover, and the same effect and arrangement will be provided.

As can be seen, the combination of the pins 26, the socket 18, the cams 30 and the spring 20 provides a readily detachable door for an instrument casing. One merely need to position the cover with the bottom of the spring 20 placed above the pins 26 and cam 30 and push down on the cover so that the pins 26 snap into the sockets 18. The cover can be removed in the opposite manner by merely rotating the cover adjacent to the closed position and by pushing up on the cover up against the force of the spring 20 so that the pins snap out from the socket 18.

With the cover 10 snapped into place, should the operator desire to open the cover, he merely rotates the cover past the balance position and the cover automatically snaps up to the open position. If the operator should thereafter desire to close the cover, he need merely rotate the cover past the balanced position and the cover snaps into the closed position. Hence, it can be seen that the cover can be opened and closed with very little effort. The combination of the cams 30 and the spring 20 provides a smooth rotational action to either the open or closed position. It has been found that the combination of the sockets, pins, cams and spring as illustrated in Figures is relatively inexpensive so that the covers can be used on a disposable basis wherein it is cheaper to replace the covers than to repair them.

Claims

What is claimed is:

1. In combination with a planar shaped cover and a housing having a planar side for receiving the cover the improvement comprising:

a pair of pins on said housing aligned along a common axis defining an axis of rotation for the cover

a pair of open sockets mounted on said cover to mate with said pins when the cover is positioned on said housing;

a leaf spring mounted, at the central portion thereof, to said cover to have its free ends extend across the open portion of the sockets and beyond said sockets, with the flat portion of the springs facing said socket,

a cam positioned on each of said pins for engaging opposite ends of said leaf spring so that when said cover is being positioned on said housing said cams urge said leaf spring away from said socket to allow the insertion of the pins into said sockets and thereafter maintain the pins in the sockets, wherein one surface of each of said cams and said axis of rotation define triangles having unequal sides, the longest side thereof defining a balanced rotational position of said cover so that when said cover is rotated from a closed position parallel to thee plane of the housing to less than the angle defined by the balanced position the cover is urged by said cams and leaf spring to the closed position and when said cover is rotated beyond the balanced position the cam and resilient means urge the cover to an open position.

2. The combination as defined in claim 1, wherein:

said cams have the general shape of a tetrahedran wherein first and second surfaces of each of said cams lie on converging planes transverse the plane of the housing side, the first and second surfaces being joined by a third surface, wherein the largest side of said triangle passes through the junction of the second and third surfaces, and when the ends of leaf springs are positioned to engage said first and third surfaces the cover is urged to the open position and when the ends of the leaf spring are positioned to engage said second surface, the cover is urged to the closed position.

3. The combination as defined in claim 2 wherein:

said first surface provides a balanced position defining the open position of said cover.