Power and manually actuated lumbosacral backrest

An improved lumbosacral backrest having a back engaging contour which is adjustable under power or manual operation to accommodate users' backs which vary widely in configuration and dimension. It has a contour defined by a segmented regulator spindle inserted between a foundation frame and resilient back support, the regulator spindle being adjustable along the back support and adapted to define a transverse plane of rigidity at the proper level and shape to provide comfortable support for the individual user's back. The backrest includes appropriate power means for actuating the regulator spindle to effect massaging action on the lumbosacral region of the back. It further includes manual means for adjusting the regulator spindle and which is operable when the power means for effecting massaging action has been deenergized.

The present invention relates to portable backrests for use with chairs, 
beds and other furniture, vehicle seats and wheelchairs. More 
specifically, the invention relates to a portable backrest of this nature 
having novel power driven or manual means for adjusting its support 
contour to accommodate individual users with backs of various physical 
dimensions. 
This invention represents an improvement over the devices disclosed in our 
prior U.S. application Ser. No. 523,660, now U.S. Pat. No. 4,541,670. 
BACKGROUND OF THE INVENTION 
The field of backrests has been the subject of developmental efforts for 
many years. This is due largely to the fact that back pain and back 
disorders afflict a major segment of the population. For a number of 
reasons such as bad posture, poor sitting habits, or poor physical 
condition, the natural elongated S-shape of the spinal column may become 
distorted. A well constructed backrest, properly adjusted, tends to 
restore the spinal S-curve to proper configuration and thereby relieves or 
avoids the uneven pressures on discs and vertebrae which cause troublesome 
pain and fatigue. 
The following prior art patents disclose a variety of backrests, some of 
which are portable and others of which are built into chairs or vehicle 
seats: U.S. Pat. Nos. 2,756,809--Endresen; 2,843,195--Barvaeus; 
2,894,565--Conner; 3,642,319--Berchicci; 3,663,055--Gale; 
3,762,769--Poschl; 3,990,742--Glass et al.; 4,350,338--Weiner; 
4,239,282--White; 3,890,000--Easley; 4,465,317--Schwartz; and French 
patent No. 1,182,558--Fader. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide an improved lumbosacral 
backrest having a back engaging contour which is adjustable under power or 
manual operation to accommodate users' backs which vary widely in 
configuration and dimension. 
Another object is to provide a backrest of the foregoing type which may be 
adjusted quickly and easily while in position behind the user. Such 
adjustment may be effected manually or by power. 
A further object is to provide a backrest of the character set forth above 
with a contour defined by a regulator spindle inserted between a 
foundation frame and resilient back support, the regulator spindle being 
adjustable along the back support and adapted to define a transverse plane 
of rigidity at the proper level and shape to provide comfortable support 
for the individual user's back. 
Another object is to provide a backrest of the character set forth above 
which includes appropriate power means for actuating the regulator spindle 
to effect massaging action on the lumbosacral region of the back. 
A further object is to provide a backrest of the foregoing type having 
manual means for adjusting the regulator spindle and which is operable 
when the power means for effecting massaging action has been deenergized. 
Still another object of the invention is to provide a backrest of the 
character set forth above which will be of simple, rugged construction, 
economical to manufacture, and require little if any maintenance. 
The foregoing is accomplished by use of a segmented regulator spindle 
interposed between the foundation frame and the resilient bowed back 
support in front of same, the regulator spindle being rotatably adjustable 
longitudinally of the back support and thereby defining a transverse plane 
of rigidity across the back support at any selected position of 
adjustment. 
The segments of the spindle are journaled on a support shaft so that they 
roll freely on the undersides of the bowed bands of the back support in a 
direction opposite to the longitudinal bodily motion of the spindle as a 
whole. The regulator spindle may be adjusted either manually or by power 
means. It may also be traversed by power means in cyclical fashion for 
back massage. 
Other objects and advantages of the invention will become apparent from the 
following description and the accompanying drawings.

While the present invention is susceptible of various modifications and 
alternative constructions, there is no intention to limit the invention to 
the specific forms illustrated and described herein. On the contrary, the 
intention is to cover all modifications and alternative constructions 
falling within the spirit and scope of the invention as set forth in the 
appended claims. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention resides in certain improvements over the backrests 
disclosed and claimed in said prior application Ser. No. 523,660, now U.S. 
Pat. No. 4,541,670. All such backrests, both those of U.S. Pat. No. 
4,541,670 and those of the present application, have certain features in 
common which should be noted prior to describing the improvements. 
Referring more specifically to FIGS. 1, 2, 4, 12 and 21, it will be 
apparent that each such figure shows a lumbosacral backrest comprising a 
foundation frame of high strength plastic or light metal. The frame has an 
out-turned peripheral margin with slightly indented areas in its two 
longer sides. It carries a flexible back support comprising a series of 
laterally spaced bands of spring steel or other resilient material secured 
to the frame by brackets in an outwardly bowed configuration. A regulator 
spindle is interposed between the foundation frame and the bands of the 
back support, serving as a contour adjusting means. A pad of resilient 
material is placed over the back support and held in position by a strong 
fabric cover C. 
Turning now to embodiment of the lumbosacral backrest 30 illustrated in 
FIGS. 1-11, the contour of the latter may be adjusted by power or by 
manual means. The backrest 30 comprises an upstanding foundation frame 31 
of generally rectangular form with stiffening ribs (not shown) and an 
out-turned peripheral margin including side portions 32 and end portions 
33. The flexible back support 34 is defined by a series of laterally 
spaced steel bands 35 of spring steel or other resilient material of 
greater length than the foundation frame 31, thereby giving the support 34 
a resilient, outwardly bowed configuration. The upper end portions of the 
bands 35 are held in place by overlying brackets 36 and the lower end 
portions are held in place by overlying brackets 37. The brackets 36 are 
spaced below the upper out-turned margin 33 of the frame by an amount 
which is at least equal to the width of an individual band. This tends to 
create a moderate biasing force urging the bands 35 against the frame 31 
and thus tending to shift the apex of their curvature to a point slightly 
below the horizontal center line of the frame. 
A contour adjusting means in the form of a regulator spindle 38 is 
interposed between the bowed spring bands 35 of the back support and the 
foundation frame 31 to adjust the contour of the yieldable back support 34 
longitudinally and transversely thereof (FIGS. 1, 4-7, 10, 11). The 
regulator spindle 38 in this instance comprises a body 39 of circular 
cross-section and an axial section of double concave form. Thus the body 
has a minimum diameter at its center, tapering gently outward to a larger 
diameter adjacent each of its ends. This disposes the yieldable support 
bands 35 in a concave orientation longitudinally of the spindle 38 and 
thereby provides a transverse plane of rigidity across the back support 
34. 
The spindle 38 is adapted to traverse the medial portion of the foundation 
frame 31 by power or manual means in the course of adjusting the contour 
of the back support. The spindle is accordingly formed with a gear wheel 
flange 40 adjacent each end thereof. Each gear wheel flange 40 is adapted 
to mesh with a guideway, in the form of a rack 41 integral with, or fixed 
to, the foundation frame 31. The racks 41 are generally parallel with the 
long dimension of the foundation frame 31 and are situated inboard of the 
indented portions 42 of the out-turned sides. The resilient bands 35 of 
the yieldable support member 34 bear against the peripheral surface of the 
regulator spindle 38. This maintains engagement between the gear wheel 
flanges 40 and the guide racks 41 and between the adjacent peripheral 
areas of the spindle 38 and the bottom surfaces of the resilient bands 35. 
Stop abutments (not shown) may be situated at the end of the respective 
guide racks 41 to prevent overtravel of the spindle. 
In accordance with the present invention, provision is made for 
dramatically reducing friction between the regulator spindle 38 and the 
overlying steel bands 35 of the back support as the spindle traverses the 
guide racks 41. Referring more specifically to FIGS. 1, 4, 10 and 11, it 
will be noted that this is accomplished by dividing the spindle body 39 
into segments 43, 44, 45, 46 47, one for each band 35, and a pair of short 
segments 48, 49 integral with the respective gear wheel flanges 40. In 
addition, each segment is formed with an axial bore and journaled on a 
common support shaft 50, the end portions of which are rigidly fixed to 
the gear wheel flanges 40. The latter may be secured in place as by 
suitable locking pins or set screws 51. 
With the regulator spindle 38 constructed as described above, when the 
spindle is moved along the guideways 41, the spindle segments 43-47 will 
roll freely on the undersides of the bands 35 in a direction opposite to 
the bodily motion of the spindle 38 as a whole. This drastically reduces 
the frictional force opposing the spindle motion and thereby reduces the 
force required to move the spindle along the guideways 41. Conversely, 
with a solid bodied regulator spindle, the spindle is rolling forward in 
the same direction as its bodily motion, creating excessive friction 
against the underside of the bands 35 and requiring excessive force to 
move the spindle along the guideways. This, in turn, requires a 
substantially larger drive motor and greater electric power to move the 
solid bodied spindle than in the case of the segmented spindle. 
Power is transmitted to the regulator spindle 38 for traversing it along 
the guideways 41 by means of a drive train (FIGS. 1, 4-7, 10). The latter 
in this case comprises a unidirectional electric motor 52, reduction gear 
53, cross shaft 54, and bevel gear set 54a, all recessed within a trough 
57 running transversely of the foundation frame 31. The drive train 
further includes dual threaded shaft 55, and drive block 56, operating in 
a large central guide trough 62 running longitudinally of the foundation 
frame. The drive block is formed with a pair of upstanding arms 58 
straddling the medial segment 45 of the regulator spindle. The support 
shaft 50 of the spindle is journaled in the upper portion of the arms 58. 
The latter have curved upper surfaces recessed slightly below the 
peripheral surfaces of the medial roller segment 45 and adjacent segments 
44, 46. 
The drive block 46 has a depending extension 59 (FIGS. 5-7) with opposed 
sides 60, 61 which slidably engage the large central guide trough 62 
formed in the foundation frame 31. The extension 59 is flanked by a pair 
of bearing surfaces 63, 64 on the underside of the guide block and which 
slidably engage mating bearing surfaces 65, 66 on either side of the guide 
trough 62. The guide block extension 59 has a central bore 68 which 
slidably receives the dual threaded shaft 55. A drive key 69, fixed to a 
pivotable support head 70 establishes the drive connection between the 
shaft 55 and the drive block 56 via the extension 59 (FIGS. 4, 5-9). The 
drive key 69 is housed in a suitable bore in the extension 59 and retained 
in place as by means of snap ring 71. 
By use of the control switch 72 and circuit indicated in FIG. 3, the 
spindle 38 may be driven by dual threaded shaft 55 and drive block 56 to 
any desired position of adjustment and stopped there by turning the switch 
to "Off" position. On the other hand, if the unit is to be used for back 
massage, the switch may be left in the "On" position and the dual threaded 
shaft will cause the regulator spindle 38 to reciprocate and thereby 
reciprocate the transverse plane of rigidity up and down the back support 
34. 
Provision is made in the backrest 30 for manually adjusting the position of 
the regulator spindle in the event electric power is not readily 
available. This is accomplished in the present instance by means of a 
spring biased manual adjusting shaft 74 aligned with the motor shaft 54. 
The shaft 74 is held in normally disengaged position by biasing spring 75. 
To engage the adjusting shaft 74 with the dual threaded shaft 55, the knob 
76 of the adjusting shaft is pushed inwardly and turned slightly until its 
bevel gear 78 meshes with the bevel gear 79 on the dual threaded shaft 55. 
By reason of overrunning clutch 80 between the reduction gear 53 and the 
motor shaft 54, the manual adjusting shaft may be freely turned to 
position the regulator spindle manually without interference from the 
drive motor 52. 
In further accordance with the invention, a modified form of regulator 
spindle 38a, shown in FIG. 11, may be provided for use in the backrest 30. 
The spindle 38a is similar in construction to the spindle 38 in that both 
are segmented in a similar manner. The spindle 38a, however, utilizes 
stepped segments 81, 82, 83, 84, 85 of different diameters rather than 
individually tapered segments. It uses a support shaft 50 identical to 
that of the spindle 38 rigidly fixed at its ends to gear wheel flanges 40 
identical to those of spindle 38. As in the case of the spindle 38, the 
stepped segments of the spindle 38a, along with the resilient pad, provide 
a highly satisfactory concave orientation for the transverse plane of 
rigidity across the back support. 
Referring next to FIGS. 12-20, a modified form of backrest 90 is there 
shown also embodying the invention. As pointed out earlier herein, the 
backrest 90 is generally similar to the backrest 30 in that the backrest 
90 utilizes a similar foundation frame 91 with out-turned peripheral 
margins 92, 94, slightly indented areas on the two longer sides, a similar 
flexible back support including flexible steel bands 96 covered by a 
resilient pad 98, a regulator spindle driven by power or manually 
positioned, and a fabric cover 99. The flexible bands 96 are held adjacent 
their ends by upper and lower brackets 36, 37 identical to those of the 
backrest 30. 
The backrest 90 utilizes a minimal friction regulator spindle 100 of the 
stepped segment type, shown in FIGS. 12 and 16. The spindle 100 includes a 
support shaft 101 running centrally through the segments 102, 104, 105, 
106, 108 and rigidly fixed at its ends to wheel flanges 109. The flanges 
109 engage V-grooves in a pair of guideways 110 generally parallel with 
the long dimension of the foundation frame and situated inboard of the 
indented portions of the out-turned sides. The spindle 100 defines a 
transverse plane of rigidity across the back support 95 which may be 
traversed upwardly or downwardly of the foundation frame 91 by power or 
manual means actuating a main drive block 111. 
In accordance with a further aspect of the invention, the spindle 100 may 
be traversed along the guideways 110 by a drive train comprising 
unidirectional motor 112, reduction gear 114, dual threaded drive shaft 
115 running laterally of the foundation frame 91, auxiliary drive block 
116 keyed to the shaft 115, and a connecting cable system. The latter 
comprises a first reach of cable 118 connected to the right hand end of 
the auxiliary drive block 116, thence around fixed guide sheaves 119, 120 
journaled on the foundation frame, thence around resiliantly biased 
take-up sheave 121 also mounted on the foundation frame, and thence 
connected to the upper end of the drive block 111. The cable system also 
includes a second reach of cable 122 connected to the left hand end of the 
auxiliary drive block 116, around fixed guide sheaves 124, 125 journaled 
on the frame 91, and thence connected to the lower end of the drive block 
116. 
It will be apparent from the foregoing that upon energizing the 
unidirectional drive motor 112, the auxiliary drive block 116 will be 
reciprocated longitudinally of the dual threaded drive shaft 115. This 
reciprocating movement will be transferred to the main drive block 111 by 
the cables 118, 122, traversing the spindle 100 back and forth along the 
guideways 110. By means of a control switch 72 and circuit such as shown 
in FIG. 3, the spindle 100 may be stopped at any desired point in its 
travel or be permitted to reciprocate for massaging action. 
The main drive block 111 (FIGS. 17, 18) in the present instance is provided 
with rollers 126 to minimize the force required to traverse it along the 
foundation frame 91. For the same objective, the block 111 is provided 
with a truncated sleeve bearing 128 to rotatably support the medial roller 
105 of the regulator spindle 100. The block 111 is also formed with a pair 
of clevises 129 and pins 130 which connect the cables 118, 122 to the 
block. 
The auxiliary drive block 116 (FIGS. 12, 19, 20) is also formed with a pair 
of clevises 131 and pins 132 for connecting the cables 118, 122 to the 
block 116. The auxiliary drive block 116 is maintained clear of the 
foundation frame 91 by the fixed cable guide sheaves 119, 120, 124, 125. 
The block 116 is connected to the shaft 115 by means of a drive key 
similar to the key 69 described earlier herein. 
The segmented regulator spindle 127 shown in FIG. 15 is of circular cross 
section and double concave form in longitudinal section. It may readily be 
used in the backrest 90 interchangeably with the stepped segment spindle 
100 shown in FIG. 12. 
The regulator spindle 100 or 127 of backrest 90 may also be manually 
positioned along the guideways 110 in a manner similar to that described 
above for the backrest 30. In this instance, a spring biased manual 
adjusting shaft 134 may be engaged with the right hand end of the dual 
threaded drive shaft 115 by pushing the knob 135 and shaft 134 to the 
left. With the drive motor disconnected by overrunning clutch 136, the 
spindle 100 or 127 may readily be positioned by turning the knob 135. In 
order to facilitate alignment of the adjusting shaft 134, dual threaded 
shaft 115, and the drive motor 112, the latter may be mounted in a recess 
138 formed in the foundation frame 91. 
FIG. 21 shows a manually actuated backrest 140 bearing general similarity 
to the backrests 30 and 90 described above except for its manual adjusting 
means comprising a rack and pinion structure. The backrest 140 utilizes a 
segmented regulator spindle 141 of double concave or tapered form 
corresponding to that shown in FIG. 22. The spindle 141 has a common 
support shaft 142 journaling the tapered segments 144, 145, 146, 147, 148. 
The shaft 142 is rigidly fixed at its ends to the unitary pinion and knob 
segments 149, 150 used for adjusting the spindle 141 along the guide rack 
members 151, 152. Thus rotating either end segment 149 or 150 will rotate 
the entire spindle. 
FIG. 22 discloses a stepped segment type regulator spindle 154 generally 
similar to that of FIG. 16 but equipped for rack and pinion adjustment in 
the manually actuated backrest of FIG. 21. The spindle 154 comprises 
stepped cylindrical segments 155, 156, 157, 158, 159 journaled on a common 
support shaft 160. As in the case of spindle 141, the shaft 160 is fixed 
at its ends to the unitary pinion and knob segments 161, 162 used for 
manual adjustment of the spindle 154 along guide rack members 151, 152. 
FIG. 24 discloses a modified type of drive block 164 adapted for use in a 
backrest such as that shown in FIG. 1. The block 164 includes a roller 
bearing assembly 165 having rollers 166 which engage the medial segment 45 
of the regulator spindle 38. It may also include additional rollers 168 
which bear against the face of the foundation frame 31 to minimize 
friction. 
While the reciprocating drive for the regulator spindles disclosed herein 
utilizes the double threaded shaft keyed to a drive block, it should be 
borne in mind that other forms of reciprocating drive may also be used. 
Such an alternate arrangement might, for example, utilize a conventional 
screw threaded shaft engaging a threaded bore in the drive block. 
Proximity limit switches and a reversing motor controller may then be used 
to achieve the reciprocating motion.