Apparatus for displacing extensible/contractible board for chair in case of emergency

Abstract: The invention relates to an unique apparatus for displacing an extensible/contractible board (5) for a chair in case of an occurrence of emergency is disclosed. The apparatus includes a board support (4), an engagement piece (6), a turn guide plate (3), a stationary guide plate (1) and an opposing pair of base members (8.1, 8.2). The board (5) assumes a horizontal attitude during normal use. In case of an occurrence of emergency, an excessive magnitude of outer force in excess of the resilient force derived from Belleville springs (7) is imparted to the board (5) by an user's hand so that the engagement piece (6) is disengaged from the turn guide plate (3) via operative engagement of an eccentric projection (52) on the board shaft (51) with an engagement recess (61) on the engagement piece (6). This causes the board (5) to be displaced from the horizontal attitude to a vertical attitude, whereby a sufficiently wide space is provided in front of an user so as to enable him to quickly escape from his chair (10). When the board (5) is not in use, the board (5) is received in a hollow space defined by an opposing pair of sleeve plates below one elbow rest of the chair.

Description: The present invention relates to a structure for supporting a retractable or foldable small table for a chair, in particular to a structure wherein the small table can quickly be turned downward to a nonobstructing position from the horizontal use position by strongly forcing it downwardly by hand to make, for example, aisles clear for allowing people to escape in case of an emergency, e.g., earthquake, fire or the like. A chair with a retractable or foldable small table is already known, in which the retractable table is forwardly taken out from under an arm rest of the chair when it is intended to use it and is retracted back under the arm rest after use. Such a small table for a chair is disclosed, for example, in US-A-3 479 084. In this prior art a small table is stored, when not in use, in a vertical plane beneath one of the armrests of the chair. The table is supported at one corner by a first support means mounted on a horizontally extending first pivot that is normal to the vertical plane of the armrest. When the table is required for use the occupant of the chair first swings the table forwardly and upwardly about said first pivot through an angle of 180°. There is a second support means that couples the table to said first support means, this second support means being swingable about a second pivot carried by the first support means, said second pivot extending in a direction transverse to the first pivot. The second pivot permits the occupant of the chair to then swing the small table downwardly to a setting in which the table is in a horizontal plane in front of the occupant of the chair. In this setting the underface of the table rests on an upper surface of the arm rest of the chair to effectively hold the table against further movement downwardly beyond said horizontal setting. In this prior art the problem to be solved is that such tables, when used for theater chairs, schoolroom chairs and the like are often carelessly allowed, when no longer required, to fall to a position where they extend at least partially forwardly forming an obstruction in the aisles between seats. To obviate this there is a helical spring between said first and second support means that serves, when the table after use has first been swung from its horizontal to it upwardly extending setting; and then forwardly and downwardly to it storage setting; to pull said table into its storage position below the arm rest of the chair. This prior art includes cam means for inactivating the force of the helical spring as the table is first raised to its vertical setting and then lowered to its horizontal setting; and also as the table is subsequently swung back until the table has been moved downwardly by a predetermined distance at which instant a finger releases said cam to allow said helical spring to be effective for moving the table wholly into its storage setting below the armrest. In a theater, a convention hall, a train, an aircraft or the like wherein a number of seats each with a retractable or foldable small table are arranged in rows, the people must pass through the space between rows of the seats to reach or leave their seats. However, it is hard to pass through the space between rows of the seats or chairs when the retractable small table is kept in a horizontal use position, forwardly protruded from the front end of an arm rest of the chair or seat.. Therefore, there is a need to lower the small table from its horizontal use position when the people intend to pass through the space, and in emergency it is necessary to quickly lower the small table to allow the people quickly to leave through the space between rows of the chairs. Consequently, an object of the present invention is to provide a new structure for supporting a retractable or foldable small table for a chair, wherein the retractable small table can quickly be turned downward from its horizontal use position into a lower non obstructing place by simply forcing the small table strongly downward by hand. Another object of the present invention is to provide a structure for supporting the retractable small table for a chair, which is not damaged or broken when an excessive external force is imparted on the retractable small table during its normal use for some reason. Another object of the present invention is to provide a structure for supporting the retractable small table for a chair, which is simple in design, smaller in dimension and low in cost. These objects are solved according the structure for the retractable small table, as defined in claim 1. Other embodiments of the present invention are defined in the dependent claims. A particular embodiment of the present invention is described in detail hereinafter with reference to the accompanying drawings which illustrate a preferred embodiment thereof. In the drawings; Fig. 1 is a perspective view showing a part of a chair with the structure according to the present invention, wherein the small table is in retracted non-use position. Fig. 2 is a perspective view similar to Fig. 1 but the table board is in intermediate position turned up before being turned sideward into the horizontal use position. Fig. 3 is a perspective view of the structure according to the present invention wherein the small table is begining to turn downward from its horizontal use position by an excessive downward force exerted on the small table. Fig. 4 is a exploded and partially broken perspective view of a part of the structure according to the present invention, wherein the small table is in position as shown in Fig. 2. Fig. 5 is a perspective view similar to Fig. 4, when the table is in the horizontal use position. Fig. 6 is a perspective view similar to Figs. 4 and 5, when the table is in the position as shown in Fig. 3. Fig. 7 is a exploded perspective view of the structure according to the present invention. As shown in Figs. 1 to 3 and Fig. 7, the structure includes an small table 5 adapted to be kept in a horizontal position during normal use and to be turned down, during an emergency say, from the horizontal use position by just forcing it downward with hand. The small table 5 is provided with a table shaft 51 which extends outward from the rear end of the table. The table 5 is supported by the supporting shaft 51 and is turnable about it. As is best seen in Fig. 7, the table shaft 5 is provided with an eccentric cam 52 at its free end which cam engages with a cam recess 61 in a locking slide 6. The table shaft is also provided with a sectorial turn stop 53 on the circumferential surface thereof which serves as a limiting member which limits the turning movement of the table when the table shaft 51 is rotated in a bearing hole 43 in a table support 4. As seen in Figs. 1 to 3 and Fig. 7, the table support 4 has two vertical sides opposing each other which are slidably contacted with the respective inner vertical side of base members 8.1 and 8.2 fixed on the front end of an arm rest 101 of a chair 10. The table support 4 is rotatably fitted on a thrust shaft 2 which extends horizontaly through the shaft hole 41 of the table support 4. The bearing hole 43 for rotatably supporting the table shaft 51 is located above the shaft hole 41 and extends at a right angle relative to the shaft hole 41. It shoud be noted that the upper half of the bearing hole 43 is contoured in the form of an arcuate recess so as to enable the sectorial turn stop 53 on the table shaft 51 to be exactly turned in the arcuate recess 44 within the range of 90 degrees. The thrust shaft 2 includes a flange portion 21 adapted to be operatively engaged with engagement projections 12 on a retaining disc 1, whereby both the thrust shaft 2 and the retaining disc 1 are held against relative rotation during the operation. The thrust shaft 2 includes a threaded portion at the opposit end, on which a nut and a pair of Belleville springs 7 are fitted. The retaining disc 1 is mounted on the thrust shaft 2 passing through the shaft hole 11 in the region adjacent to the flange portion 21. The shaft hole 11 is formed at the central portion of the retaining disc 1. The retaining disc 1 is provided with two semicylindrical engagement projections 12 adapted to be engaged with the corresponding engagement recesses 32 on a turn control disc 3, one of the engagement projections 12 being located above the shaft hole 11 and the other one being located below the shaft hole 11. To assure that the retractable small table 5 can be used also in a case where it is installed on other side arm rest, the retaining disc 1 is provided with the same engagement projections as the engagement projections 12 on the reverse side. In this case, the flange portion 21 of the thrust shaft 2 is brought in between a pair of the engagement projections on the reverse side. The retaining disc 1 is formed with a cutout 13 in the circumferential portion which is engaged with a adjusting screw 9 threaded through a threaded hole 84 in the base member 8.1. The adjusting screw 9 is used to adjust an initial angular position of the retaining disc 1 so that the table will be horizontal in its horizontal use position. The base member 8.1 is fastened to the front end of an arm rest 101 of the chair 10 with set screws or the like, as shown in Figs. 1 to 3. After the retaining disc 1 is fitted on the thrust shaft 2 at the position adjacent to the flange portion, the turn control disc 3 is likewise fitted thereon at a position adjacent to the retaining disc. The turn control disc 3 is provided with a shaft hole 31 at the central part thereof through which the thrust shaft 2 is inserted. In addition, the turn control disc 3 is provided with two semicylindrical engaging recsses 32 on the outer vertical side that are adapted to come into engagement with the engaging projections 12 of the retaining disc 1. One of the engaging recesses 32 is located above the shaft hole 31 and the other one is below the shaft hole 31. Further, the turn control disc 3 is provided with a locking aperture 33 on the right side to receive the locking slide 6. To ensure that the apparatus can be used for the left side arm rest located opposite to the arm rest 101 shown in Fig. 2, the turn control disc 3 is additionally provided with an other locking aperture 33 on the left side, as shown in Fig. 7. Additionally, to restrict the turning angle of the table 5 about the thrust shaft 2 when the table 5 is moved forwardly out of a hollow space 103 defined between an opposing pair of sleeve plates 102 below the arm rest 101 or when the table 5 is moved back into the hollow space, the turn control disc 3 is provided with an arcuate groove 34 extending along the circumference in the reverse side opposite to the side having the engaging recesses 32. The one end of the locking slide 6 is always projected by Δ 1 from the side of the table support and inserted in the arcuate groove 34 so as to be moved along the grooves 34 in accordanc with the turning motion of the table 5. The table support 4 is provided with a shaft hole 41 and turnably mounted on the thrust shaft 2 which extends through the shaft hole 41. The table support 4 is also provided with a guiding hole at a position behind the shaft hole 41 relative to the table 5. The guiding hole 42 extends in parallel with the shaft hole 41 and is kept in alignment with the locking aperture 33 in the turn control disc 3 so that the locking slide 6 can be inserted into the locking aperture 33. The locking slide 6 having a cam recess 61 is slidably inserted in the guiding hole 42 and the eccentric cam 52 on the table shaft 51 is engaged with the engaging recess 61 of the locking slide 6. As the table 5 is turned about the axis of the table shaft 51 to take the horizontal use position, the locking slide 6 is moved by the eccentric cam 52 so that the projected end of the locking slide 6 enters into the engaging aperture 33 of the turn control disc 3 whereby the table support 4 is locked in its place and the table 5 is held in the horizontal use position. The second base member 8.2 includes a bearing hole 86 for the thrust shaft 2 at the center of its side wall and a spring accomodating chamber 85. The threaded portion 22 of the thrust shaft 2 is inserted through the bearing hole 86, each center aperture of a pair of Bellevlle springs 7 and a washer in turn, and a nut is threaded onto the threaded portion 22. By tightening the nut, a required resilient force is produced to press the retaining disc 1, the turn control disc 3 and the table support 4 against each other. As shown in Figs. 1 to 3, the apparatus described above is attached to the chair 10 by fastening the first and the second base member 8.1 and 8.2 on the front end of the right side arm rest 101. When the table 5 is not needed, the table 5 is kept in a retracted vertical position in a hollow space 103 below the arm rest 101. When the table 5 is intended to be used, it is turned up by an angle of 180 degrees about the thrust shaft 2 until the table shaft 51 is put in its forward horizontal position, as shown in Fig. 2. Then the table 5 is turned about the table shaft 51 to take the horizontal use position in front of a user. At the same time, the eccentric cam 52 on the table shaft 51 is turned in the same direction to move the locking slide 6 into the locking aperture 33. The engaging end of the locking slide 6 is projected by the eccentric cam 52 of the table shaft 51 away from the side of the table support 4 by Δ 1, before the table 5 is turned sideward into the horizontal use position. Once the table 5 has been turned sideward in that way, the projected end of the locking slide 6 is projected further outward by an increased quantity of projection Δ 2, as shown in Fig. 5. With such increased projection of the locking slide 6, the projected end of the lockig slide 6 is inserted into the locking aperture 33 of the turn control disc 3 and the table 5 is locked in the horizontal use position. Since the engaging projections 12 of the turn stop disc 1 are firmly engaged with the engaging recesses 32 of the turn control disc 3 under the effect of the resilient force of the spring 7, the table 5 is stably supported in the horizontal use position during its normal use. However, when an excssive magnitude of downward force Σ is exerted on the table 5 by the user's hand as shown in Fig. 3, the engaging projections 12 of the retaining disc 1 are pushed out of the retaining recesses 32 of the turn control disc 3 against the resilient engaging force of the springs 7 and the turn control disc 3 is released from the retaining disc 1 so as to be allowed to turn about the thrust shaft 2. As a result, the table support 4 is also allowed to turn about the thrust shaft 2, the table 5 is turned down from its horizontal use position into a nonobstructing setting. Since the table 5 is released and turned downward as described above when an unusualy strong force is exerted on the table 5, the apparatus according to the present invention is protected from being damaged. Although the present invention has been described with respect to a single embodiment, it should of course be understood that it should not be limited only to this but various changes or modificaftions may be made in an acceptable manner without departure from the scope of the invention as defined by the appended claims. For example, in the above-described embodiment, Belleville springs 7 are used as the engagement assuring means, however, it should be understood that the present invention should not be limited only to the spring 7. Alternatively, a solenoid adapted to generate the same intensity of resilient force as that of the springs 7 may be substituted for the spring 7 with the same operative results.

Claims: An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency, whereby a table support (4) serves to turnably support said table (5), said table support (4), being formed with a bearing hole (43) for rotatably receiving a table shaft (51) made integral with said table (5), an arcuate recess (44) for turnably receiving an arcuate projection (53) on said table shaft (51), said arcuate recess (44) being of greater radius than the bearing hole (43) and contoured on an outer extension in cross section of said bearing hole (43), a shaft hole (41) through which a thrust shaft (2) is inserted, said shaft hole (41) extending at a right angle relative to the table shaft (51) and being located below said bearing hole (43), and a slide hole (42) for slidably receiving an engagement piece (6), said slide hole (42) being located at a position behind the shaft hole (41) relative to the table (5); that the engagement piece (6) is slidably received in the slide hole (42) of the base support (4), said engagement piece (6) having an engagement recess (61) formed thereon so as to allow an eccentric projection (52) on the table shaft (51) to be engaged with said engagement recess (61); that a turn guide plate (3) is disposed adjacent to the table support (4) to guide turning movement of the table (5) and the table support (4), said turn guide plate (3) being formed with a shaft hole (31) at the central part thereof through which the thrust shaft (2) is inserted, an engagement aperture (33) located in alignment with the slide hole (42) of the table support (4) so that a foremost end of the engagement piece (6) is inserted therethrough when the engagement piece (6) is projected outwardly of the table support (4) by turning movement of the table (5) via operative engagement of the eccentric projection (52) of the table shaft (51) with the engagement recess (61) of the engagement piece (6), an opposing pair of engagement recesses (32) for receiving a first opposing pair of engagement projections (12) on a stationary guide plate (1), one of said engagement recesses (32) being located above the shaft hole (31) and the other one being located below the shaft hole (31), and an arcuate guide groove (34) for allowing the foremost end of the engagement piece (6) to slidably move therealong when the table (5) is turned from a horizontal attitude and thereby the engagement piece (6) is retracted from a projected state via said operative engagement of the eccentric projection (52) of the table shaft (51) with the engagement recess (61) of the engagement piece (6); that the stationary guide plate (1) is immovably held on the thrust shaft (2) which extends through a shaft hole (11) at the central part thereof, said stationary guide plate (1) being formed with a second opposing pair of engagement projections (12) adapted to receive a flange portion (21) of the thrust shaft (2) to hold the thrust shaft and a threaded portion at its fore end against rotation, said second engagement projections (12) being located opposite to said first engagement projections (12); that the thrust shaft (2) extends through a shaft hole (86) of one base member (8.2) at a right angle relative to the table shaft (51), said one base member (8.2) being one of an opposing pair of base members (8.1, 8.2) firmly secured to the front surface at the foremost end of one elbow rest (101) of the chair (10) with the table support (4) interposed adjacently therebetween, one (8.1) of said base members receiving the turn guide plate (3) and the stationary guide plate (1) in a hole (83) formed therein and the other one (8.2) of said base members having a spring receiving hole (85) formed therein, and that engagement assuring means (7) serves to firmly hold the table support (4), the turn guide plate (3) and the stationary guide plate (1) in an operative engagement relationship under the effect of resilient force derived from said engagement assuring means (7). An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that said engagement assuring means (7) comprises a plurality of Belleville springs for resiliently biasing the table support (4) and the turn guide plate (3) toward the stationary guide plate (1), said Belleville springs being received in the spring receiving hole (85) of the one base member (8.2). An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that said engagement assuring means (7) comprises a solenoid for biasing the table support (4) and the turn guide plate (3) toward the stationary guide plate (1). An apparatus for displacing an extensible/contractible table (5) for a chair (10) as claimed in claim 1, characterized in that each of the engagement projections (12) on the stationary guide plate (1) is contoured in the form of a semicylindrical projection and each of the engagement recesses (32) on the turn guide plate (3) is contoured in the form of a semicylindrical recess. An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that the turn guide plate (3) is formed with another engagement aperture (33) which is located symmetrical to the first-mentioned engagement aperture (33) so as to assure that the apparatus can be used also for other elbow rest (101) of the chair (10). An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that the stationary guide plate (1) is formed with a cutout (13) with which the foremost end of a set screw (9) comes in contact so that the stationary guide plate (1) is immovably held on the thrust shaft (2). An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that a depth of the arcuate glide groove (34) of the turn guide plate (3) is determined to coincide with a quantity of retractive displacement of the engagement piece (6) at the time when the table is turned from the horizontal attitude to a vertical attitude. An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that the arcuate projection (53) on the table shaft (51) serves as turning movement limiting means for limiting the range of turning movement of the table (5) from the horizontal attitude to the vertical attitude. An apparatus for displacing an extensible/contractible table (5) for a chair (10) in case of an occurrence of emergency as claimed in claim 1, characterized in that the table (5) is received in a hollow space (103) as defined by an opposing pair of sleeve plates (102) when the table (5) is not in use.

Inventors: YAMAZAKI RYOKICHI, YAMAZAKI, RYOKICHI
Applicants: KOTOBUKI & CO LTD, KABUSHIKI KAISHA KOTOBUKI
Application year: 1990
Main classification: A47C7
IPC codes: B60N3, A47C7