US 3774965 A
The dental chair includes a back unit pivotally mounted on a seat unit which in turn is tiltably carried on a vertically adjustable base unit. Each unit has a corresponding reversible operating motor. An arm rest pivotally supported on the back unit is movable to an upright position to actuate a switch on the back unit for simultaneously operating the motors to move the units to relative positions to provide for an upright or seated chair position. When the arm rest is moved to an arm supporting position the switch is actuated to simultaneously operate the motors to move the units to relative positions providing for a reclined chair position. The upright position and reclined position are automatically defined by limit switches corresponding to the units and operatively associated with their respective motors.
Description (OCR text may contain errors)
United States Patent [191 Brandt et al.
[ Nov. 27, 1973 DENTAL CHAIR WITH A SWITCH ACTUATING ARM REST  Inventors: William P. Brandt; James D.
Huffman, both of Des Moines, Iowa  Assignee: Den-Tal-EZ Mfg. C0., Des Moines,
22 Filed: Feb. 28, 1972 211 Appl. No.: 230,020
 U.S. Cl. 297/417, 297/350  Int. Cl B60n 1/06  Field of Search 297/327, 330, 340,
 References Cited UNlTED STATES PATENTS 1/1952 McFadden 297/359 3/1965 Naughton 297/417 X 3,188,043 6/1965 Dlouay 297/347 X 3,276,816 10/1966 Edwards 297/359 3,495,872 2/1970 Gielow et al.. 297/340 3,578,379 5/1972 Taylor 297/330 1126,241 8/1967 Naughton 297/418 Primary ExaminerPaul R. Gilliam Attorney-Rudolph L. Lowell ABSTRACT The dental chair includes a back unit pivotally mounted on a seat unit which in turn is tiltably carried on a vertically adjustable base unit. Each unit has a corresponding reversible operating motor. An arm rest pivotally supported on the back unit is movable to an upright position to actuate a switch on the back unit for simultaneously operating the motors to move the units to relative positions to provide for an upright or seated chair position. When the arm rest is moved to an arm supporting position the switch is actuated to simultaneously operate the motors to move the units to relative positions providing for a reclined chair position. The upright position and reclined position are automatically defined by limit switches corresponding to the units and operatively associated with their respective motors.
4 Claims, 7 Drawing Figures PAIENIEBxuv 27 1915 3,774,965
SHEET 1 BF 2 DENTAL CHAIR WITH A SWITCH ACTUATING ARM REST SUMMARY OF THE INVENTION The arm rest actuator provides fora simultaneous operation of all of the chair motors to automatically move the seat, back and base units to stop positions defining either a seated position or a reclinedposition for the chair and eliminates the necessity of the chair operator manipulating several switches whenever a person tion of the chair the armrest is extended upwardly along one side of the back unit. Thus, with a person seated in the chair, movement of the arm rest to an arm supporting position automatically provides for movement of the chair to a reclined position without requiring any further manipulation of the arm rest. Conversely, when a person is in a reclined position in the chair and is to be released from the chair, it is only necessary to move the arm rest from the arm supporting position to the upright position adjacent one side of the back unit. On movement of the chair to a seating position the arm rest remains in the upright position so as to permit the unobstructed movement of a person out of and into the chair. Chair movement toeither a reclined or seated position can be interrupted by actua-. tion of a power disconnect switch carried in the back unit or by movement of the arm rest from a then moved position thereof to its other moved position. Additionally, should the automatically provided reclined or seated chair positions require additional adjustment to accommodate the chair occupant, the several chair motors can be independently operated by independent actuation of corresponding separate switches carried on the back unit.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a dental chair equipped with the switch actuating arm rest of this invention and showing the chairin an upright or seating position;
FIG. 2 is illustrated similarly to FIG. 1 and shows the chair in a reclined position;
FIG. 3 is a perspective view of the dental chair illustrated in an intermediate moved position with parts broken away to show the chair operating motors and some of the control switches;
FIG. 4 is an enlarged detail perspective view of a portion of the back unit showing the assembly therewith of the arm rest and some of the motor control switches;
FIG. 5 is an enlarged detail elevational view showing the assembly relation of the arm rest with a switch device for simultaneously operating all of the chair motors;
FIG. 6 is a sectional view taken along line 6 6 in FIG. 5; and
FIG. 7 is the electrical circuit for the chair motors and control switches therefor.
DETAILED DESCRIPTION OF THE INVENTION With reference to the drawing there is shown in FIG. 1 a contour dental chair 10 equipped with the switch actuating arm rest 11 of this invention. The chair l0 has a curved leg and seat unit 12 and a back unit 13 pivotally connected at its lower end to the rear section of the seat unit 12 for pivotal movement to upright and reclined positions. The seat unit 12 is supported for longitudinal tilting movement on a vertically adjustable base unit 14. The back unit 13 (FIG. 3) is moved between its upright and reclined positions by means ineluding a motor 16; the seat unit 13 is tiltably moved relative to the base unit 14 by means including a motor 17 and the base unit 14 is vertically adjusted by means including a motor '18. The mechanical construction of the back unit 13 and seat unit 12 of the chair 10 are disclosed in Naughton U. S. Pat. No. 3,172,699 and the construction of the vertically adjustable base unit 14 is disclosed in Naughton U. S. Pat. No. 3,472,488.
The arm rest 11 and an associated arm rest 19 (FIG. 3) are mounted on the back unit 13 for forward extension to opposite sides of the seat unit 12. An upright support 21 pivotally connected to the seat unit 12 and to the arm 19functions to control the position of the arms 11 and 19 with respect to the back rest unit 13 on pivotal movement of the back rest unit with respect to the seat unit 12. As illustrated, each arm rest 12 and 19 is provided with a flexible arm support 22 disclosed in Naughton U. S. Pat. No. R. 26,241.
During movement of the back rest unit 13 relative to the seat unit 12, the arms 12 and 19 are arranged to maintain the arms of a patient substantially parallel with his legs whereby to maintain a comfortable position of the arms at all times regardless of the relative positions of the seat and back units. Each of the arm rests 11 and 19 is formed of a round rod material having laterally bent rearward end sections 23 and 24, respectively (FIG. 4), projected within and rotatably supported on the back unit 13 as by bearings 26, indicated only for the arm 11 in FIG. 5. The rear end sections 23 and 24 (FIGS. 4 and 5) are interconnected by a transversely extendedconnecting member 27 having a reduced central section 28 integrally formed at its ends with enlarged tubular bearings 29 and 31 for rotatably receiving therein the arm rest rear sections 23 and 24, respectively. Bearings 29 and 31 are formed at the outer ends thereof with extensions 32 and 33, respectively, of a semi-circular shape in transverse cross section and concentrically arranged with corresponding rear sections 23 and 24 of the arm rests 11 and 19 also respectively.
The rear section 24 of the arm. 19 (FIG. 4) is connected by a pin 34 to the bearing 31 so that theconnector member 27 is pivotally moved or rocked in response to the pivotal movement of the arm rest 19. The rear section 23 of the armrest 1 1 is rotatable within its associated bearing 29 between limits defined by the engagement, with opposite ends 35 and 36 of the semicircular extension of a pin 37 projected radially from the rear section 23 of the arm 11. The upright position of the arm 11 is defined by the engagement of the pin 37 with the end 35 of the extension 32 (FIG. 5). The
arm supporting position of the arm 11 is defined by the engagement of the pin 37 with the end 36 of the extension 32 (FIG. 4).
By virtue of this engageiable position of the pin 37 with the extension 32 rockable movement of the arm 19, in response to the pivotal movement of the upright support 21, is transmitted to the arm 11 through the pin 37. The arms 11 and 19 are thus always maintained in positions to comfortably support the arms of a patient.
In other words, when the back unit 13 pivots backwardly and downwardly from its position in FIG. 1, to the position therefor shown in FIG. 2, the arms 11 and 19 are not only maintained transversely parallel and aligned but they are also moved rearwardly and lowered relative to the seat unit 12 to accommodate the changed positions of the arms of a patient. Thus, upon movement of either the seat unit 12 or the back unit 13 the arm 11, when in the lower position of FIG. 4, is always movable with the arm 19.
However, it will be noted that when the arm 19 is extended forwardly, as shown in FIG. 1, the arm 11 is movable relative thereto to an upright position along one side of the back unit 13 as illustrated in FIGS. 1 and 5. This relative movement is permitted because the pin 37, on upward movement of the arm 11, from its position in FIG. 4, is moved out of engagement with the end 36 of the semi'circular extension 32 and into engagement with the extension end 35 to its positions shown in FIG. 5. Conversely, the arm 1 1 is movable relative to the arm 19 from its upright position, shown in FIG. 5, to its forwardly extended position, shown in FIG. 4, by movement of the pin 37 out of engagement with the end 35 and into engagement with the end 36 of the semi-circular extension 32. It is thus seen that the arm 11 is pivotally movable relative to the arm 19 to the positions therefor shown in FIGS. 4 and 5. Also, it will be seen that when the arm 11 is in its upright position of FIG. that the arm 19 is pivotally movable relative thereto, but when the arm 11 is in its lowered position of FIG. 4, the arms 1 1 and 19 are movable as a unit in response to the pivoted movement of the upright support 21.
On movement of the arm 11 relative to the arm 19 to either position shown in FIG. 4 or FIG. 5, the chair motors 16, 17 and 18, which are of a reversible type, are simultaneously operated to automatically adjust the chair to either the upright position of FIG. 1 or to the reclined position of FIG. 2, depending upon the moved position of the arm 11. Thus, when the arm 11 is in the lowered position (FIGS. 2 and 4) movement thereof to the upright position (FIGS. 1 and 5) automatically adjusts the chair 10 to the upright position of FIG. 1 providing for the release of the patient from, or entry into, the chair 10. In this adjustment the motors 16, 17 and 18 are simultaneously operated to provide for a forward pivotal movement of the back unit 13, a forward and downward tilting movement of the seat unit 12, and a vertical retraction of the adjustable base unit 14. On movement of the arm 11 from its upright position in FIGS. 1 and 5, to-the lowered position in FIG. 4, the seat unit 12, back unit 13 and base unit 14 are simultaneously moved to automatically adjust the chair to its reclined position shown in FIG. 2.
For this purpose the rear section 23 of the arm 11 is provided outwardly from but adjacent to the bearing 29 with a circular cam 38, the axis of which is radially offset from the axis of the arm rear section 23. A spacing collar 39 is mounted on the section 23 between the cam 38 and the arm bearing 26. Both the cam 38 and the collar 39 are fixed to the arm rear section 23 by set screws 41 and 42, respectively.
The cam 38 is operatively associated with a follower roller 43 that is mounted on and forms part of an actuating unit 44 of a switch device 46 located within the back unit 13 at a position below the cam 38. The switch device 46 is of a make-before-break type manufactured by Micro Switch of Freeport, Ill. and designated as number BZ-2GW822A2 and forms part of a symmetrical electrical system (FIG. 7) which operates in response to pivotal movement of the arm 1 1 to adjust the chair 10 to either a seated position or a reclined position. Thus, let it be assumed that the chair 10 is in the reclined position of FIG. 2 and is to be automatically adjusted to the upright or seated position of FIG. 1.
In the reclined position of the chair 10 a hold-in relay R1 (FIG. 7), is maintained in a hold-in position by the switch device 46. The relay R1 is of single-pole doublethrow type and the one used by applicant is No. 3l 1010-24 made by Cornell-Dubilier. On movement of the arm 1 1 from its lowered position in FIG. 4, corresponding to the reclined position of the chair, to the upright position therefor in FIG. 5, the roller 43 of the switch device 46, is engaged by the arm cam 38, as shown in full lines in FIG. 6, to move a first spring contact finger 47 (FIG. 7) thereof into engagement with a terminal 48 to close the circuit for a four-pole doublethrow relay R2. This relay is also available from Cornell-Dubilier as No. Al-O4AO-1 15V. However, due to the make-before-break characteristic of the switch device 46 a second spring contact finger 47a thereof continues to engage a terminal 480 of the hold relay R1. The hold circuit for the relay R1 from one side or lead 49 of an electrical source 51 includes a power disconnect or master switch 52, the contact finger 47a, normally closed contacts 53 of a relay RlA, a diode 54, and lines 56, 57, 58 and 59 to a lead line or ground 61 of the electrical source 51. The relay RlA is identical in all respects to the relay R1.
The hold of relay R1 provides for the closing of its normally open contacts 62, so that on engagement of the spring contact 47 with the terminal 48 the circuit for activating the relay R2 from the terminal 48 includes the contacts 62, line 63, relay R2 and lines 64, 58 and 59 to the lead line 61. Energization of the relay R2 provides for the closing of its normally open contacts 66, 67 and 68 to provide for the operation of the chair motors 16, 17 and 18, respectively. Concurrently, the normally open contacts 69 of the relay R2 are closed for a purpose to appear later.
As shown in FIG. 7 the circuit for the back unit motor 16 from the lead line 49 includes the contacts 66, line 71, having connected therein normally closed limit switches 72 and 73, motor 16 and lead line 61. In like manner the circuit for the seat unit motor 17 includes the contacts 67, line 74, having limit switches 76 and 77, motor 17 and lead line 61. Similarly, the circuit for base unit motor 18 comprises the contacts 68, line 78, having limit switches 79 and 81, motor 18 and lead line 61. The closing of the circuits for the motors 16, 17 and 18 provides simultaneously for a forward pivotal movement of the back unit 13, a forward and downward tilting movement of the seat unit 12, and a retractible movement of the base unit 14 to relative adjusted positions defining an upright or seated position of the chair 10 as shown in FIG. 1. The adjusted position of the chair units 12, 13 and 14 is determined by the selected positioning of the limit switches 72, 76 and 79, respectively, in the paths of movement of the chair units 12, 13 and 14. As a result, opening of the normally closed limit switches 72, 76 and 79, in turn, open the circuits of their associated motors 16, 17 and 18, respectively.
The closing of the circuits for the chair motors 16, 17 and 18 simultaneously energizes diodes 82, 83 and 84 for supplying current to relay R1. The diodes are of a common readily available type known asIN2070. Each diode 82, 83 and 84 is connected in an associated line 86, 87 and 88, respectively, each of which has one end 1 connected to a corresponding line 71, 74 and 78, also respectively, at a position between corresponding pairs of limit switches in the lines 71, 74 and 78. The opposite ends of the diode lines 86, 87 and 88 are connected to one side of the normally open contacts 69 of the relay R2. The opposite side of the contacts 69 is connected to line 56 ata position to supply current to relay R1.
With the closing of the circuits for the motors 16, 17 andl8 and the diodes 82, 83 and 84, the spring contact finger 47a of the switch device 46 will have moved out of engagement with the terminal 48a to a position adjacent to the spring contact finger 47. The switch device 46 has thus moved to what may be referred to as the RlA and R2 relays side of the symmetrical circuit. However, since the normally open contacts 69 of the relay R2 are closed, thecircuits for the diodes remain energized to provide for a continued holding action by the relay R1.
On opening of the limit switches 72, 76 and 79 to stop the operation of their respective motors 16, 17 and 18, the circuits for the diodes 82, 83 and 84 are simultaneously opened whereby further current flow from the diodes to the relayRl is discontinued. As a result of this current discontinuance, the relay R1 is deenergized to in turn provide for a de-energization of relay R2 by the return of the contacts 62 of relay R1 to a normally open position. However, relay RIA will continue to hold by virtue of the supply of current thereto through the normally closed contacts 89 of the relay R1. The diodes 82, 83 and 84 have the character istic of permitting only a uni-directional flow of current therethrough so as to prevent current feed back. If a feed back current was permitted the operation of a motor 16, 17 or 18 would be continued after the opening of anyone of the limit switches 72, 76 or 79.
Additionally, it will benoted that the holding circuits for the relays R1 andRlA are operated at 24 volts D. C. from the source5l of 1 volts A.C. This operation takes place by the use of the diodes 54 and 54A connected into the lines 56 and 56A, respectively. These diodes lower the H0 volt A. C. to approximately 35 volt half-wave D. C. Resistor 91 and 91A then drop the voltage supplied to the relays R1 and RIA, respectively, to approximately 24 volts. Capacitors 92 and 92A for the corresponding relays R1 and RIA then smooth out the half-wave D. C. current to eliminate buzzing in the relays. As a result, the relays R1 and RIA are capable of being operated continuously over extended periods of time without becoming overheated.
When the arm rest 11 is moved from its upright position in FIG. 5 to its lowered position in FIG. 4, the cam 38 moved out of engagement with the roller 43, as shown in dotted lines in FIG. 6, to provide for the return movement of the spring contact fingers 47 and 47a of the switch device 46. This return movement of the contact fingers 47 and 47a provides for the other half of the symmetrical electrical system functioning in the same manner as the half of the electrical system just described in connection with the movement of the arm rest 11 from its lowered position to the upright position therefor. Similar numerals therefor having a suffix letter A have been used to designate the like parts in the half portion of the electrical system that was not hereinabove specifically described.
It is seen, therefore, than when the arm 11 is in the upright position the relay RlA is always in the hold position along with providing for the energization of the relays R2 and R1 to control the operation of the motors l6, l7 and 18. On movement of the arm 11 to a lowered position, the relay RIA through the make-beforebreak action of the switch device 46 remains momentarily energized to provide for the energization of the relays R2A and R1, after which the circuit for the relay RIA is broken. When this break occurs the relay R1 holds until the arm rest 11 is again moved from a lowered to an upright position. A reverse movement of the arm 11 relative'to the switch device 46 thus provides for an automatic movement of the chair units 12, 13 and 14 to upright or reclined positions therefor without requiring any further attention by the chair operator.
The power disconnect switch 52 functions as a master switch to connect and disconnect the switch device 46 relative to the electrical source 51 or, when necessary, to immediately interrupt the movement of the chair between the upright and reclined positions therefor. Let it be assumed that the arm 11 is in its upright position providing for movement of the chair 10 to an upright or seated position. Let it be further assumed that this movement is interrupted by actuation of the switch 52 to disconnect the switch 46 from the power source 51. If the movement of the chair 10 to its seated position is to be continued, the arm 11 must first be moved from the upright position to the lower or forwardly extended position thereof, after which the disconnect switch 52 is again immediately actuated. On then resetting the arm in its upper position the chair 10 will continue movement toward the upright or seated position therefor.
This relative sequence of actuation of the arm 11 and disconnect switch 52 is required because of the makebefore-break characteristic of the switch device 46. It will be understood, of course, that movement of the chair 10 between its upright and inclined positions can be interrupted or stopped at any time merely by movement' of the arm 1 1 to one or the other of its moved positions shown in FIGS. 4 and 5.
It will be appreciated that the automatic movement of the chair 10 to a reclined or seated position may require further adjustment of the chair units 12, 13 and 14 to accommodate different size patients. To provide for this additional adjustment, the automatically moved positionsof the chair units, as determined by the limit switches 72, 76 and 79 and 72A, 76A and 79A, are within the maximum range of movements for the chair units.
The maximum range of movements is controlled by the limit switches 73, 77 and 81 and 73A, 77A and 81A. Thus, assume that the chair 10 has been moved to either its reclined position or upright position and that additional adjustment is required. As shown in FIGS. 3 and 4, each side of the back unit 13 carries a series of three vertically arranged. like manually actuated switches 94, 96 and 97 of single-pole doublethrow type. The switches 94 (FIG. 7) are connected directly to the lead line 49 and in parallel between lines 98 and 98A which are connected to lines 71 and 71A,
respectively, between the limit switches 73 and 73A, also respectively. Depending upon the actuated position of a switch 94, the back unit motor 16 will be operated to pivotally move the back unit 13 either forwardly or rearwardly to a desired position or until further movement is arrested by opening of one of the limit switches 73 or 73A. in a like manner the switches 96 are connected to the seat motor 17 through lines 99 and 99A, lines 74 and 74A and limit switches 77 and 77A, all respectively; and the switches 97 are connected to the base motor 18 through the lines 101 and 101A, lines 78 and 78A and limit switches 81 and 81A, all respectively.
It will, of course, be understood that the manual switches 94, 96 and 97 may be actuated to move the chair to an adjusted position so long as the disconnect switch 52 is in its circuit opening or power disconnect position.
Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes can be made therein which are within the full intended scope of this invention as defined by the appended claims.
1. A dental chair comprising:
a. a back unit, a seat unit and a base unit each of which is operatively associated with a corresponding reversible motor means and wherein the back unit is pivotally movable relative to the seat unit, the seat unit is longitudinally tiltable relative to the base unit and the base unit is vertically adjustable,
b. an arm rest pivotally mounted on said back unit for manual pivotal movement to a first position extended upwardly along one side of said back unit and to a second position projected forwardly from said one side of the back unit, and
c. an electrical control circuit for said motor means including a single switch device on said back unit having an actuating lever movable, in response to the movement of said arm rest to the first position therefor to a first circuit closing position to simultaneously operate said motor means in one direction d. normally closed limit switches in said control circuit corresponding to said motor means and mounted on the chair for engagement by corresponding ones of said units to automatically stop said motor means to define said relatively moved positions of said units.
2. The dental chair according to claim 1 wherein: a. said circuit includes a manually actuated control switch unit mounted on said back unit operable to connect and disconnect said single switch device relative to a source of electrical power.
3. The dental chair according to claim 2 wherein: a. said circuit includes a plurality of normally open manually actuated switch means on said back unit and corresponding to said motor means, for connecting said motor means directly to said source of electrical power,
b. said switch means, when said back unit, seat unit and base-unit are in one or the other of said relatively moved positions, being selectively actuated to move said back unit, seat unit and base unit independently of each other to final adjusted relative positions therefor.
4. The dental chair according to claim 3 wherein: a. said circuit includes other normally closed limit switches mounted on said chair corresponding to said motor means, with each of said other limit switches connected in series with a corresponding one of said manually actuated switch means to limit the movement of said back unit, seat unit and base unit to maximum moved positions therefor in response to an actuation of said manually actuated switch means.