US 3240935 A
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March 15, 1966 J. DOUGALL 3,240,935
TILTABLE X-RAY EXAMINATION TABLE STRUCTURE Filed May 16, 1963 4 Sheets-Sheet 1 )n/VENToR JOHN 8 MM+QMM March 15, 1966 J. DOUGALL 3,240,935
TILTABLE X-RAY EXAMINATION TABLE STRUCTURE Filed May 16, 1963 4 Sheets-Sheet 2 ,Mswma J. DOUGALL March 15, 1966 TILTABLE X-RAY EXAMINATION TABLE STRUCTURE 4 Sheets-Sheet 5 Filed May 16, 1963 vN EA/ToR IOHA/ DDUGALL J. DOUGALL March 15, 1966 TILTABLE X-RAY EXAMINATION TABLE STRUCTURE 4 Sheets-Sheet 4 Filed May 16, 1963 JbH/V 000% L L United States Patent 3,240,935 TILTABLE X-RAY EXAMINATION TABLE STRUCTURE John Dougall, Gillnock, Scotland, assignor to Associated Electrical Industries Limited, London, England, a British company Filed May 16, 1963, Ser. No. 280,957 Claims priority, application Great Britain, May 18, 1962, 19,303/ 62 3 Claims. (Cl. 250-55) This invention relates to tiltable table structures particularly but not exclusively to such structures as used for supporting patients for X-ray diagnosis or examination.
In a common form of tiltable X-ray table structure as used in hospitals, provision is made for mounting a viewing screen above the table in alignment with an X-ray tube below the table (considering the table in its horizontal position) and for permitting the aligned screen and tube to be moved both lengthwise and transversely of the table so as -to bring. the screen into any desired position over a person lying on the table.
Provision is usually also made for interposing a loaded X-ray film cassette between the patient and the screen so as to obtain a radiograph of the X-ray image, and further provision may be made for bringing an over-table X- ray tube into position (the screen being moved out of the way) and taking a radiograph with a film cassette brought into alignment beneath the table. In order to enable a patient to be examined not only when lying horizontally but also in other positions including vertically upright (or nearly so), the table may be tiltable about a transverse axis between a vertical tilting limit in which it is inclined vertically upright and a reverse tilting limit in which it has a reverse inclination. Some tables are made which can be tilted to a vertically upright position in the reverse direction as well as in the vertical direction, but usually a maximum reverse tilt of about 45 would be acceptable.
In designing a tiltable table with under-mounted X-ray tube or other equipment, a compromise has to be struck between certain mutually conflicting desiderata. Firstly it is desirable to keep the table as low as possible in order to facilitate getting on and off and also to facilitate viewing of an over-table screen, the minimum height of which in the horizontal position of the table will be determined by the table height. In order to obtain a desired image size on the screen with a minimum angle divergence of the X-ray beam from an under-table tube, it is also desirable to have the X-ray tube as far below the table as possible, but this conflicts with the requirement for minimum table height and the spacing of the tube from the underside of the table is further restricted because of the necessity of ensuring that, with the tube at either extreme of its lengthwise travel, the tube will remain clear of the floor when the table is tilted.
To permit the table to tilt to a vertically upright position, the height of the tilting axis has to be sufi'icient to ensure that the lowering end of the table remains clear of the floor during tilting: the height of the axis is therefore a function of the distance between it and the table end, and for this reason the table may be arranged for forward and reverse tilting about ditferent axes respectively nearer the opposite ends of the table. However the closeness of the tilting axis to an end of the table is restricted not only by considerations of counter-balancing but also by the desirability of keeping to a minimum, for convenience of the operating staif, the increase in viewing screen height as the table is tilted: this means keeping the rise of the table itself to a minimum at the position along it at which the screen is most often used, which is over a patients chest. On tilting about an axis too near 3,240,935 Patented Mara 15, 1966.
the foot end of the table, the rise of the table at the screen position, and therefore the screen height, would increase considerably with angle of tilt especially through the initial part of the tilt.
An object of the invention is to provide an improved tiltable table arrangement which permits the foregoing desiderata to be more nearly satisfied as regards horizontal table height, distance below table at which an X-ray tube or other equipment can be mounted, and rise of table at an intermediate position on tilting- According to the invention there is provided a tiltable table structure in which the table is pivoted about a transverse tilting axis on a support lever which is itself pivoted about another axis preferably also transverse to the table and horizontally further from one end of the table than is the tilting axis, namely so that the distance of the lever axis from that end of the table, measured horizontally when the table is horizontal, is greater than that of the tilting axis from that end. Means is provided for tilting the table forward about its axis on the lever so that one end swings down (being the end already referredto when the lever axis is transverse) and further means effective at least during the later part of the forward tilting is provided for pivoting the lever about its axis in such sense as to raise the tilting axis. As a resultthe forward tilting takes place accompanied at least in the later stages by a raising of the tilting axis. This means that at what would otherwise have been a limiting position of forward tilt because further tilting would have caused the lowering end of the table or under-mounted equipment to hit the floor, the tilting can be continued because the raising of the tilting axis can keep the table and under-mounted equipment clear of the floor. Consequently in the horizontal position the tilting axis can be lower than it could have been if fixed, so that the table can also be lower. Also the tilting axis can be further from the lowering end of the table than would otherwise be the case, so that the rise of the table at anintermediate position in its length (such as would cor-respond for instance to a chest examining position of an X-ray table viewing screen) will be commensurately less for a given angle of tilt. With the lever pivoted on a transverse axis and inclining upwardly from this axis to the table axis, as is preferred, the raising of the table axis by the pivoting of the lever'will be accompanied by a reduction of the distance between the two axes as measured horizontally, an eflect which becomes more pronounced as the table comes nearer to its vertical position. This has the effect of drawing in the table towards the position of the lever axis so that, in the case of an X-ray table for instance, less end wall clearance will be required to permit frontal observation of a viewing screen when the table has been forwardly tilted to or near the vertical. Also less change of position is required of the operator between the horizontal and vertical table positions.
With the lever pivoted on a transverse axis, reverse tilt of the table from horizontal can be achieved by pivoting the lever alone while maintaining a fixed angular orientation between it and the table.
While the means for tilting the table and pivoting the lever about their respective axes may have separate prime movers, for instance separate pneumatic or hydraulic jacks, it is possible and advantageous to have a single jack or other prime mover acting on both through suitable mechanical linkage. Co-ordination of the operation of the two means can also be achieved by such a linkage: for instance a link actuated by forward tilting of the table may itself actuate a secondary lever which, at least after a predetermined table inclination has been reached (for instance an inclination such that the lowering end of the table or an under-mounted equipment is closely approaching the floor), acts on the main lever so as to cause it to pivot about its axis and thereby start to raise the table axis. For this purpose the secondary lever may be pivoted to the main lever and may, at a predetermined point in the tilting, engage an abutment which, by its reaction on the secondary lever combined with the actuating force in the link referred to, causes the required pivotal movement of the main lever.
An embodiment of the invention incorporating such a linkage arrangement is illustrated by way of example in the accompanying drawings in which FIG. 1 is a general perspective rear view of a tiltable X-ray table structure embodying the invention and FIGS. 2-5 are front views showing the tilting mechanism of the table in various positions. FIG. 2 shows the mechanism in the horizontal position of the table, FIG. 3 shows it with the table in a partially forwardly inclined position, FIG. 4 with the table tilted fully forward to a vertical position, and FIG. 5 with the table tilted to the limit of its reverse tilt.
FIG. 1 shows the general arrangement of a tiltable X-ray table structure embodying the invention. The table 1 shown in its horizontal position is fully cantilevered and is supported only at the rear, where it has an attachment bracket 2 (FIG. 2) connected to a supporting and tilting mechanism housed in a pedestal 3. A cantilevered structure 4, which carries a viewing screen 5 and may also include a carriage (not shown) by which an X-ray film cassette can be moved into position beneath the screen, is supported on legs 6 which are telescopically accommodated in a rear support 7. The support 7 is mounted on a structure (indicated in outline only) which extends through a slot 9 in the rear of the table structure 1. This structure 10 carries an undertable X- ray tube 11 in vertical alignment beneath the screen 5 and is rail-mounted for movement transversely of the table on a carriage (not shown) which is itself rail-mounted beneath the table top for movement lengthwise of the table. The structure 10 can therefore be adjusted in position both transversely and longitudinally of the table, taking the X-ray tube 11 and screen structure 4 with it. The assembly 4-5-7-1041 tilts with the table. The screen structure 4 can be removed by raising it so as to extract its telescopic legs 6 from their sockets in the support 7, it being contemplated that for this purpose an overhead gantry may be provided running on rails so as to permit the structure 4 to be moved completely clear of the table top. A further gantry on the same rails may carry an over-table X-ray tube which, with the screen structure 4 removed, can be brought into vertical alignment with a rail-mounted film cassette carriage (not shown) provided beneath the table top and movable along the length of the table. With gantria provided as aforesaid for the screen structure 4 and an over-table X-ray tube it is contemplated that these items of equipment may be left suspended from their gantries while in use over the table, being counter-balanced through their supsensions to facilitate height adjustment. It will be noted that the front side of the table is completely clear of obstructions which could hinder or inconvenience operating staff at work. Also with the structure 4 removed access to the top of the table from the rear is virtually unobstructed.
In FIGS. 2-5 the screen structure 4 has been shown in a position approximating to that which it would occupy for chest examination. In order not to obscure the view of the tilting mechanism, the under-table X-ray tube 11 and its supporting structure 10 have been omitted from these figures, but the extreme position of'the X-ray tube 11 at the limit of movement of the assembly 4-5- 7-10-11 towards the foot end of the table has been indicated at 11'. The tilting mechanism has to ensure that with the tube in this extreme position it Will not foul the floor if the table is tilted forward to its vertical up right position.
Corning now to the tilting mechanism, the attachment bracket 2 by which the table is carried is pivotally mounted on a tilting axis a near one end of a main lever 12, which near its other end is itself pivotally mounted in the pedestal 3 on a fixed axis b. A piston operated ram 13 is pivtoally secured at its outer end to the bracket 2 at a position (0) such that on extension of the ram a turning moment about the axis a will be applied to the bracket 2 such as to tilt the table in the forward direction. The rear end of a hydraulic or pneumatic cylinder 14 accommodating the operating piston for the ram 13 is pivotally secured in the pedestal 3 on a fixed axis d. A secondary lever 15 intermediately pivoted on the main lever, at e, carries a roller 16 at one end and at the other end is coupled to the bracket 2 by a link 17. Link 17 is pivoted at one end to bracket 2 and is pivoted at its other end to secondary lever 15. The disposition of this link is such that during forward tilting it is actuated from the bracket 2 and urges the lever 15 in a clockwise direction about the axis e.
The forward tilting action is as follows. Starting in the position shown in FIG. 1 admission of pressure to the cylinder 14 so as to extend the ram 13 results in movement of the various parts of the mechanism according to the arrow-headed full lines. The bracket 2, and with it the table 1, begin to be tilted forward about axis a. Link 17, after initially urging the lever 15 anticlockwise (namely until the link passes through the position at which it is radial to axis a) urges lever 15 clockwise so that its roller 16 approaches a horizontal rollerway 18. When the roller 16 reaches the rollerway 18 the various parts of the mechanism have the relative dispositions shown in FIG. 3, and it is arranged that this occurs when the under-table X-ray tube 11, if in its extreme position 11', is just clear of the floor 19. The front end of the table is also still clear of the floor.
Continued extension of the ram 13 produces movements according to the arrows in FIG. 3. The table 1 continues to be tilted about its axis a and the link 17 continues to urge the lever 15 clockwise. However due to the engagement of the roller 16 with the rollerway 18 the roller end of the lever 15 is constrained to move horizontally. Consequently the pivot axis e of this lever on the main lever 12 is caused to rise, taking with it the main lever 12 which until now has remained stationary against a stop 20. The lever 12 therefore pivots about its axis 11 away from the stop 20, progressively raising the tilting axis a and at the same time drawing it in horizontally (towards the left in the figures). The raising of the axis a combined with the continued tilting of the table about this axis causes the lower edge of the table to follow the locus 21 and the lowest point of the X-ray tube 11 when in position 11 to follow the locus 22, it being observed that both loci remain clear of the floor. The table finally reaches the vertically upright position as shown in FIG. 4 with the ram 13 fully extended.
Reverting to FIG. 2, admission of reverse pressure to the cylinder 14 so as to retract the ram 13 will produce movements as indicated by the arrow-headed dotted lines in this figure. The tendency of the bracket 2 to be reverse-tilted about its axis a by the retraction of the ram 13 is prevented by a stop 23 which during the reverse tilting maintains a fixed angular relationship between the table and the main lever 12. Retraction of the ram 13 therefore acts so as to pull the lever 12 upwards about its axis b unaccompanied by tilting of the table about its axis a. Reverse tilting of the table structure about the lever axis b therefore takes place until as shown in FIG. 5 the limit of reverse tilt is reached with the ram 13 fully retracted.
Both forward and reverse tilting can of course be stopped and held at any intermediate inclination.
What I claim is:
1. A tiltable X-ray examination table structure comprising a support base; a table; a support lever on which the table is pivotally mounted about a transverse tilt axis and which is itself pivoted on said support base about another axis; a linearly extensible operating member acting between said support base and the table, said operating member being coupled to the table at a point spaced from said tilt axis and being actuatable to tilt the table in a forward direction of rotation about the tilt axis; and a coordinating mechanical linkage connected between the table and support lever comprising a secondary lever connected to the support lever at a point removed from its pivot axis on the support base and a link connecting this secondary lever to a point on the table removed from said tilt axis, said link being responsive to tilting of the table in the forward direction to actuate the secondary lever and cause it, at least after a predetermined inclination of the table has been reached, to pivot the support lever about its pivot axis on the support base in such sense as to raise said tilt axis.
2. A tiltable X-ray examination table structure comprising a support base; a table; a support lever on which the table is pivotably mounted about -a transverse til-t axis and which is itself pivoted on said support base about another axis; a linearly extensible operating member acting approximately parallel to the support lever and having pivotal connections by which it is connected between a fixed point on the said support base and a point of connection to the table so located in relation to said tilt axis as to permit tilting of the table in a forward direction of rotation from a horizontal position by variation of the effective length of said operating member in one sense; a secondary lever pivoted to the support lever at an intermediate point on each of these levers; a link connected between one end of the secondary lever and a point of connection to the table so located in relation to said tilt axis that tilting of the table in said forward direction will cause the link to produce pivotal movement of the secondary lever in the sense to move the other end of this secondary lever downwardly; and a generally horizontal abutment surface on said support base positioned so that on continued pivotal movement of the secondary lever its said downwardly moving end will come into engagement with said surface with consequent reaction on the secondary lever, said reaction raising the pivotal connection point of the secondary lever and support lever whereby to pivot the support lever in the sense to raise said tilt axis.
3. A table structure according to claim 2, wherein in the horizontal position of the table the effective length of said operating member is also variable in the sense opposite to that for tilting the table in the torw-ard direction, whereby to tend to tilt the table in the reverse direction, and said structure further includes stop means preventing such reverse tilting of the table with respect to the support lever whereby such opposite sense variation of the length of the operating member is effective to tilt the table and the support lever together in reverse direction about the support lever pivot axis on said support base.
References Cited by the Examiner UNITED STATES PATENTS 2,568,236 9/1951 Kizaur 250 2,680,046 6/1954 Stava 250- 55 2,872,584 2/1959 Schiring et a1 25055 3,069,543 12/1962 Sazavsky 25055 RALPH G. NILSON, Primary Examiner.
ARCHIE BORCHELT, Examiner.