Tilt mechanism for display terminal

An inexpensive tilt mechanism for a display terminal includes a pair of L-shaped rails at the bottom surface of the terminal. The rails define a channel extending from front to back at the bottom surface. At least one of the rails has a toothed surface. A movable support includes a pedestal attached to a base plate which can be shifted along the channel defined by the L-shaped rails. In a preferred embodiment, only one of the rails has a toothed surface while the pedestal has an attached lever which can be used to pivot the movable support about the other rail until it clears the teeth. In this disengaged position, the movable support can be shifted along the channel.

FIELD OF THE INVENTION 
The present invention relates to display terminals and more particularly to 
an inexpensive tilt mechanism for a display terminal. 
DESCRIPTION OF THE PRIOR ART 
Display terminal users often want to be able to adjust the tilt of their 
terminal for a variety of reasons. If glare from overhead lights is a 
problem, a user may tilt the terminal forward until the screen faces away 
from the lights or toward the floor. This is referred to as a negative 
tilt orientation. Alternatively, a user whose terminal is resting on a 
relatively low surface may wish to tilt the terminal backward until the 
screen faces toward the ceiling. This is referred to as a positive tilt 
orientation. 
The mechanisms for allowing users to make this type of adjustment range 
from something as simple as a book placed beneath the terminal to 
something as elaborate as an electromechanical or even a hydraulic 
mechanism which allows an operator to tilt or swivel the terminal or to 
change its vertical elevation. Placing a book beneath the terminal may 
have the virtue of being cheap, but often isn't practical. For example, a 
user can't look at a book when his terminal is resting on it. Of greater 
consequence is the fact that a book, or any other makeshift support, may 
block the flow of needed cooling air through the terminal or may be 
accidentally dislodged. If the latter happens, the terminal obviously may 
be damaged when it crashes onto the primary supporting surface. 
Less impromptu forms of terminal support may not possess the disadvantages 
of a book, but can add significantly to the cost of a terminal due to 
their complexity. A number of mechanisms have been divulged which provide 
not only tilt, but also swivel capability. Examples of these mechanisms 
may be found in U.S. Pat. Nos. 4,304,385, 4,365,779, 4,395,020, 4,410,159, 
4,415,136, 4,453,687, 4,494,720, 4,500,060, 4,542,872 and 4,554,590. 
While the tilt and swivel mechanisms disclosed in the above-listed patents 
or wlsewhere in the prior art vary considerably in their mechanical 
details, all are relatively complex due to the requirement for mechanical 
components capable of providing the swivel function. 
Where a user does not have to be able to swivel a display terminal, 
potentially less expensive tilt-only mechanisms may be used. A number of 
different tilt mechanisms are disclosed in issued patents. Examples of 
such mechanisms can be found in U.S. Pat. Nos. 3,538,250, 3,740,011, 
4,349,173, 4,368,867, 4,427,243, 4,471,931, 4,474,352, 4,524,940, 
4,527,766, 4,533,105, 4,556,189 and 4,561,620. 
While these known prior art mechanisms perform a basic tilt function in 
many different ways, most include a number of moving parts. This adds to 
the initial cost of manufacture and assembly while increasing the 
possibility of failure during normal terminal use. 
SUMMARY OF THE INVENTION 
The present invention is an inexpensive tilt mechanism for a display 
terminal. The tilt mechanism has a single movable part which reduces the 
initial cost and the possibility of failure during terminal use. 
In a preferred embodiment, the mechanism makes use of a retaining means 
which extends from front to back at the bottom surface of the display 
terminal. The retaining means has at least one engageable surface. A 
movable terminal support includes a base plate which is received within 
the retaining means. The base plate can be moved along the path defined by 
the retaining means. A terminal supporting pedestal extends away from the 
base plate or toward any surface on which the terminal rests. The movable 
support includes a locking means which is adjacent to but disengageable 
from engageable surface of the retaining means. The locking means, when 
disengaged, permits selective movement of the movable support along the 
defined path. When engaged, the locking means holds the movable support in 
place.

TECHNICAL DESCRIPTION 
FIG. 1 is a perspective view showing the left side, rear and bottom surface 
of a display terminal 10. The orientation or tilt of a display terminal 10 
can be adjusted by means of an inexpensive tilt mechanism including a 
movable support 12 which can be shifted along a retaining means 14 
extending from the front to the back of the terminal 10 at its bottom 
surface. The position of the movable support 12 within the retaining means 
determines the orientation or tilt of the terminal 10. 
Referring to FIG. 2, when support 12 is at or near the face 16 of terminal 
10, the face is tilted toward a terminal supporting surface 18. If the 
movable support 12 is shifted towards a rear surface 20 of terminal 10, 
the face 16 can assume a zero tilt or vertical orientation as shown in 
FIG. 3. If the movable support 12 is moved closer to the rear surface 20, 
the terminal will assume a positive tilt orientation, as shown in FIG. 4. 
FIG. 5 is a more detailed perspective view of the movable support 12. The 
movable support 12 includes a base plate 22 and a terminal supporting 
pedestal 24, preferably formed with a crate-like construction for strength 
purposes. The terminal supporting pedestal 24 includes an actuating lever 
26 and a small upwardly extending ridge 28. The functions of the lever 26 
and ridge 28 are described with reference to later figures. 
FIG. 6 is a partial perspective view of the movable support 12 in position 
in the retaining means 14. A preferred embodiment of retaining means 14 
comprises two parallel rails 30 and 32, preferably formed integrally with 
the bottom surface 34 of the display terminal 10. Each of the rails 30 and 
32 has a generally L-shaped cross section to define a channel extending 
from the front to the back of the display terminal. The base plate 22 
rides within the defined channel. The thickness of base plate 22 is less 
than the vertical dimension of the channel so the movable support 24 can 
move a limited vertical distance within the channel. In a preferred 
embodiment, rail 32 includes a bottom surface which may be engaged by 
movable support 24 to lock the support in position. In the illustrated 
embodiment, the engageable surface comprises a series of teeth 34A, 34B, 
34C, etc. The ridged surface 28 on the movable support 12 can be received 
in a space between two adjacent teeth. 
FIG. 7 shows the movable support 12 in an engaged position. In this 
position, the upper surface of the base plate 22 and the lower surface of 
the pedestal 24 are generally parallel to the bottom surface 34 of the 
terminal while ridge 28 on pedestal 24 is trapped between two of the teeth 
on rail 32. Surface 38 on the pedestal 24 rests against the smooth bottom 
surface of the rail 30. 
To disengage the movable support so that it can be shifted for or aft in 
the channel defined by the L-shaped rail 30 and 32, a terminal user lifts 
lever 26 vertically as shown in FIG. 8. As lever 26 moves upwardly, the 
pedestal 24 pivots about the point of contact between the bottom surface 
of rail 30 and the surface 38 of pedestal 24. The pivotal movement allows 
ridge 28 to clear the teeth on the bottom surface of rail 32. As long as 
lever 26 is held at its uppermost vertical position, the movable support 
can be shifted along the channel defined by rail 30 and 32 to any desired 
position. When the desired position is reached, lever 26 is released. The 
weight of the terminal will cause the movable support to return to the 
engaged position shown in FIG. 7. 
FIG. 9 is a partial perspective view of an alternate embodiment of the 
invention. In this embodiment, a retaining means 40 consists of two 
L-shaped rails 42 and 44, each of which has teeth formed along its bottom 
surface. As was the case with the embodiment described earlier, the 
retaining means 40 is preferably an integral part of a bottom wall 46 of a 
terminal housing. A movable support 48 includes a tab 56 extending from 
one side of movable support 48 and a base plate 50 which can be shifted 
along the channel defined by the rails 42 and 44. The thickness of the 
base plate 50 is less than the vertical dimension of the channel so that 
movable support 48 has a limited range of the vertical movement. The 
movable support 48 lacks any actuating level but includes shoulders 52 and 
54 which can be received in the slots between the individual teeth on the 
bottom surface of the rails 42 and 44. 
To adjust the tilt of the terminal equipped with this embodiment of the 
tilt mechanism, the operator lifts the terminal clear of its primary 
supporting surface. When the weight of the terminal is removed from the 
movable support, the vertical play of the base plate 50 within the channel 
allows shoulders 52 and 54 to drop clear of the toothed surfaces. The 
movable support 48 will slide forward in the channel with minimal urging 
by the operator. If the movable support is to be moved to the rear, the 
operator may have to depress tab 56 when pushing the movable support 48. 
Pressure on tab 56 will prevent the base plate 50 from rotating within the 
channel in such a way that shoulders 52 and 54 of movable support 48 come 
into unintended contact with the teeth on rais 42 and 44. When the desired 
position is reached, the terminal is lowered towards its primary 
supporting surface. The movable support 48 is locked into position when 
the shoulders 52 and 54 enter gaps between adjacent teeth on both rails. 
While there have been described what are considered to be preferred 
embodiments of the invention, variations and modifications therein will 
occur to those skilled in the art. Therefore, it is intended that the 
appended claims shall be construed to include the described embodiments 
and all such variations and modifications as fall within the true spirit 
and scope of the invention.