US2267908A - X-ray timer safety attachment - Google Patents

Description

Dec. 30, 194 E R. GOLDFIELD ET AL 2,257,908

X-RAY TIMER SAFETY ATTACHMENT Filed July 51, 1940 2 Sheets-Shet 1 FlGrl Q INVENTORS EDWIN R. LDF'IELD EgvyARD B. GRAVES FIG-2 M f ATTOIRNEYS Patented Dec. 30, 1941 X-RAY TIMER SAFETY ATTACHMENT Edwin. R. Goldfleld, University Heights, and Edward B. Graves, South Euclid, Ohio, assignors to Picker X-Ray Corporation,

facturing Division, Inc.,

poration of Ohio Waite Manu- Cleveland, Ohio, a cor- Application July 31, 1940, Serial No. 348,854

7 Claims.

This invention relates to improvements in a timer for controlling X-ray tube exposures.

An object of the present invention is to prevent operation of an X-ray tube for undesirably long periods of time at undesirably heavy loads. It is Well known that the operation of a tube at a heavy load for too long a period of timewill result in early destruction of the tube and therefore the present invention is directed to the prevention of the combination of a heavy load and long exposure.

In the embodiment of the invention here disclosed the tube control circuit is disabled upon the setting of the control means simultaneously for a heavy load and a long exposure, but obviously the results may be accomplished in other ways, as for instance by positively preventing the simultaneous setting of the control means for a heavy load and a long exposure.

The invention consists also in the arrangement of the structures herein disclosed to perform the functions ascribed to them and the essential features thereof will be et forth in the claims.

In the drawings, Fig. 1 is a front elevation of one embodiment of our invention with a portion of the front panel broken away to more clearly show the structure; Fig. 2 is a top plan view of the same embodiment with a portion thereof in section to more clearly illustrate the construction; Fig. 3 is a fragmental sectional View taken along the line 3-3 of Fig. 2; Fig. 4 is a sectional view taken along the line 4-4 of Fig. 1; while Fig. 5 is a diagrammatic view of the control circuits.

Referring first to the diagram of Fig. 5, We have disclosed our invention as applied to a conventional X-ray tube l having asupply of high tension current from the secondary I I of a transformer whose primary I2 is connected by leads l3 and M with an autotransformer IS. A switch IS in the lead I3 is controlled by a relay I 1 to initiate tube operation as will presently appear. Filament current is supplied from the filament transformer l8 whose primary 18a receives current through leads I 9 and 20 from the autotransformer. Resistance 2| is inserted in this primary circuit, the setting of which is controlled by movement of the contact arm 22 to one of the series of contact buttons 23. The arrangement of the parts is such as viewed in Fig. that the lower buttons correspond to lighter load and the upper buttons correspond to heavier loads as will be apparent to one skilled in the art.

Our improved safety control involves a circuit for energizing the relay I! with a control therefor which is tied up with the filament current control arm 22 so that when the timer in the control circuit is set for long exposures and the filament control is setfor a heavy load the relay ll cannot be energized and switch l6 will remain open. The circuit for controlling the relay I 1 comprises a source of current L3, L4, one side of which is connected by lines 24 and 25 with relay I1 and the other side of which is connected by lines 26 and 21 with relay H. In the line 26, 2! is a switch A which is a pilot switch for controlling relay and a switch B which is operated by the timer. to be presently described. Switch A comprises contact 21a connected with line 21 and a similar contact connected with line 26 spaced vertically below 21a in Fig. 2. Bar 44b carried by lever 44 serves to connect the two contacts. The switch A is controlled by the relay 28 which is connected with the source L3, L4 by lines 26 and 29, line 30 and a group of parallel connections 3i, am, 311), 3lc, 31d and 32. These connections are selected by arm 33 which is connected by common control means 34 with the filament load selector arm 22. The arrangement is such that when the control arm 33 contacts any one of the selector buttons 35, the arm 22 is in contact with the similarly located button 23 in the filament control circuit. A manually controlled switch 38 in line 24 places the control of switch A and therefore of relay I! at all times within the immediate control of the operator so that the tube operation may be discontinued at any time. Regarding the parallel connections at 3| and 32 which have just been mentioned it will be noted that line 3| leads through switch C to the plurality of connections numbered from 3m to 3| (1 of which the connections 3la and 3| b are under control of switch D, the connection 3lc is controlled by switch E, and the, connection 34d is subject to control by switch 0 only. Obviously the connection at 32 is effective independent of the setting of switches C, D and E.

In the embodiment here disclosed timing means is provided for controlling the time of interval of tube operation and, certain settings of that timer, causes opening of switches C, D and E so that if the filament selector arm 22 is set for certain loads the arm 33 will at the same time contact certain of the buttons 35 which lead through the connections 31a to 3 id just described and therefore the energizing circuit for controlling relay ll and switch I6 will be disabled for certain settings of the control means.

Our safety control idea may be applied to timers of various types but is here illustrated in connection with a timer having a member settable for various time intervals and this control member is driven back to a circuit opening position by a motor. This construction is best seen in Figs. 1 to 4 wherein the settable member is indicated at 31 as being secured to the front face of a large gear 38 mounted on a shaft 39 and freely rotatable thereon. This shaft is carried in fixed bearing 49. Freely rotatable on the shaft 39 is a clutch member 4Ia which coacts with a clutch member Mb also mounted on shaft 39. The clutch member 41b is normally biased out of engagement with the coacting clutch member but is pressed into engagement by a ball 42 which is controlled by an arm 43 which in turn is an extension of lever 44. This lever has a pivot at 45 and the end 44a of the lever forms the armature of relay 28 which also serves to close switch A. The member 31 is visible through an annular opening 46 in the front panel 41. Various time settings are indicated on the front panel, as for instance a lower range indicated at 48 and a higher range indicated at 49. Selection of these two ranges will be later described. The clutch member Ma is normally biased in a clockwise direction as viewed in Fig. 1 and carries an arm 50 which engages a stop pin 3811 which projects from the rear face of gear 38, A spiral spring urges the arm 50 into engagement with the stop pin 38a. The clutch member Mb is driven in a direction to turn the clutch member Ma in a counterclockwise direction as viewed in Fig. 1 when the clutch members are engaged. The driving means for clutch member Mb is gear 52 which may be selectively driven by one of two gear trains providing a driving connection with gear 53 mounted on shaft 54 and driven by motor 55 through speed reducing mechanism 56. A gear shifting bracket 51 is pivotally mounted on shaft 54 and carries two sets of gears either of which may be selectively placed in operation by oscillation of the bracket 51. One set of gears for high speed operation comprises pinion 58 and gear 59 both rigidly mounted on shaft 69. Pinion 58 meshes with gear 53 and gear 59 meshes with gear 52 when the parts are in the position of Fig. 3. The other set of driving gears comprises pinion GI and gear 62 both rigidly mounted on shaft 63. The gear 62 meshes with gear 53 and the pinion BI is adapted to drive gear.

52 at slower speed when the bracket 51 is oscillated in a counterclockwise direction from the position of Fig. 3. It is thus possible to drive the clutch member Ma at a higher speed through the gear train 58, 59 for short exposures or to drive the clutch member 4! a at slower speed through the gear train 3|, 62 for longer exposures.

Means is provided for controlling the position of bracket 51 so as to select longer or shorter ranges of exposure. The means here disclosed comprises a knob 64 on the control panel connected by shaft 65 with adisk 6B which has mounted eccentrically thereon the bent arm 61a of a rod 31 extending upwardly through an opening in bracket 51. A yieldable connection between rod 6'! and bracket 51 is provided by the coil springs 68 and 69 above and below the bracket 51. These springs are held in position by the collars 70 and 1! respectively. When the parts are in the position of Fig. 1 the setting is for the faster speed and when the arm 61a is moved to the dot-dash position of Fig. 1 the setting is for the slower speed.

The means for setting the timer comprises a knob 12 on the control panel which operates shaft 13 so as to rotate gear 14 which in turn rotates gear 15 which meshes with gear 38. Thus rotation of the knob 12 produces the desired setting of stop pin 38a which is indicated by the position of the member 31.

The means which controls the setting of the timer just described also controls switches D and E previously described, These switches are alike and are carried by arms 16 which are adjustably clamped on a shaft 11 which is in turn carried by a bracket 18. Rotatably mounted on shaft 11 is gear 19 which meshes with pinion which in turn is rotated by shaft 8| upon rotation of gear 15 also carried by shaft 81. A pin 19a on gear 19 engages the throw 82 of switch D at one point in its path of travel and engages the throw 83 of switch E at another point in its path of travel. As viewed in Fig. 1, switches D and E are open when their throws are toward the right and are closed when their throws are toward the left. The gear 19 moves in the direction of the arrow indicated thereon when the timer is moved for longer exposures. Therefore the pin 19a opens switch D at relatively shorter time exposures and opens switch E at relatively longer time exposures. Thus it will be apparent that as the knob 12 is turned to set the timer it results in a rotation of gear 19 so that if that gear turns far enough in the direction of the arrow switch D or E or both will be opened if the timer is turned for long enough exposures. It will be apparent from a consideration of Fig. 1 that the turning of gear 19 in the counterclockwise direction will again close switches E and D as pin 19a passes the throws 83 and 82 respectively.

From the description above given it will now be apparent thatwith the lowest load setting shown in Fig. 5 the selector arm 33 contacts with the lowermost button 35 so as to place line 32 in the control circuit and no setting of the timer will affect this .control circuit insofar as switches C, D and E are concerned. Thereupon operation of button 36 will cause an exposure for whatever time is set. This time is controlled by the setting of the member 31 and the stop pin 38a which controls the position of arm 50 on the clutch member Ma. Upon the closing of button 35 relay 28 is energized closing switch A which energizes relay IT to close switch I 6 and start operation of the X-ray tube. As will be obvious from Fig. 2 the closing of switch A occurs simultaneously with the movement of lever 44 to engage the clutch members whereupon the arm 50 is driven back toward a zero position where the arm engages an extension 84 of switch B opening the switch and. deenergizing relay l'l, whereupon switch l6 opens under the influence of its spring and tube operation ceases. Relay 28 is deenergized by release of button 36 whereupon the clutch is disengaged and spring 5| returns arm 50 into contact with stop pin 33a ready for the next operation. Arm 50 engages stop 81 after switch B is opened and the clutch slips until button36 is released.

If the timer is set for a period of time requiring the turning of gear 19 beyond the point Where switch D is opened then obviously if the control shaft 34 is turned so that selector arm 22 is in engagement with either of the two uppermost buttons 23 then the selector arm 33 will likewise be in engagement with one of the two uppermost buttons 35. For such a settin of the control means the control circuit is then interrupted through open switch D and it will be impossible to energize relay I! to cause operation of the tube.

If the timer setting requires a still longer time interval and hence a further turning of gear 19 in a clockwise direction as viewed in Fig. 1, pin 19a will also cause opening of switch E. Under these conditions if control shaft 34 is turned so that selector arm 22 engages the third button from the bottom then selector arm 33 will engage the corresponding button 35 and the control circuit through switch E will be open making it impossible to energize relay I!v or to operate the tube.

In the above descriptions of various operations including switches D and E, it has been assumed that switch C was closed because the parts were in the position of Fig. 1. Assuming now that control knob 64 is rotated to raise rod 61 then bracket 51 will be oscillated to establish the gear train giving a slower speed to clutch member 4lb. This corresponds with longer intervals of time exposure. Under these conditions an arm 85 causes movement of the throw 86 (Fig. 1) upward to open switch C. Referring now to Fig. 5, it will be obvious that opening of switch C disables the control circuit if the selector arms 22 and 33 are on any. but the lowermost buttons and therefore tube operation cannot be procured by operating button 36 except at the lowest tube load.

From the above description it will be seen that we have provided means for automatically preventing operation of the X-ray tube at predetermined combinations of heavy load and long exposure. This control is so arranged that at intermediate time intervals intermediate loads are possible and at shorter time intervals heavy loads are possible but the main object of this invention is accomplished to prevent use of the longest time exposures at the heaviest tube loads.

What we claim is 1. In X-ray tube control apparatus, an X-ray tube, means for operating said tube, control means therefor including a control circuit having portions selectively connectable in series therein, means for controlling the output of said tube adjustable for lower and higher ranges, means for controlling the time of tube operation, said means including a movable selector adjustable for longer and shorter ranges, means operable coincidentally with said output control means for placing selected portions of said control circuit in series respectively upon various settings of the output control means, and means operable by said movable time selector at predetermined points along its path of movement for breaking said control circuit portions.

2. In X-ray tube control apparatus, an X-ray tube, means for operating said tube, control means therefor including a starting circuit, means for controlling the output of said tube having various settings, adjustable means including a movable selector for controlling the time of tube operation, means operable coincidentally with said output control means for establishing a portion of said starting circuit by a given setting of said output control means, and means operable by said movable selector at a predetermined point along its path of movement for breaking said starting circuit.

3. In X-ray tube control apparatus, an X-ray tube, means for operating said tube, control means therefor including a control circuit having portions selectively connectable in series therein, means for controlling the output of said tube having various settings, adjustable means including a movable selector for controlling the time of tube operation, common control means for establishing a setting of said output control means and for coincidentally connecting a corresponding portion of said control circuit, and means operable by said movable selector at predetermined points of its adjustment for breaking said circuit portions.

4. In X-ray tube control apparatus, an X-ray tube, means for operating said tube, means for controlling the output of said tube having various settings arranged progressively from low load to high load, control means for said tube operating means including a control circuit having portions selectively connectable in series therein, common control means for establishing settings of said output control means and for coincidentally connecting a corresponding portion of said control circuit whereby certain control circuit portions are coordinated respectively with higher and with lower load settings of said output control means, there being a switch in each of said control circuit portions, adjustable means for controlling the time of tube operation, and means actuated by said last named means at predetermined points of its adjustment for opening said switches, the parts being so located that as said time control means moves from shorter to longer time adjustments it opens first said switch in a circuit portion coordinated with a higher load setting and it opens second said switch in a circuit portion coordinated with a lower load setting.

5. The combination of claim 4 including means actuated by said time control means as it moves from longer to shorter adjustments for closing first said switch in a circuit portion coordinated with a lower load setting and for closing second said switch in a circuit portion coordinated with a higher load setting.

6. Control apparatus for an X-ray tube having operating means and a control circuit therefor and means for timing tube operation, said timing means including a settable time control member and a two-speed motor drive means for driving said time control member, a speed control member for selecting either of the speeds of said drive means, two switches in said control circuit, means for opening one of said switches by a predetermined setting of said time control member, and means for opening the other of said switches by a predetermined movement of said speed control member.

7. Control apparatus for an X-ray tube having operating means and a control circuit therefor, means in said control circuit having settings for low and high'er tube outputs, means for timing tube operation, said timing means including a settable control member and a two-speed motor drive means for driving said time control member, a speed control member for selecting either of the speeds of said drive means, two switches in series in said control circuit when set for said higher tube outputs, and means for opening one of said switches by movement of said speed control member for selecting one of said speeds.

EDWIN R. GOLDFIELD. EDWARD B. GRAVES.

Images