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

• US 5,087,096 A
• Filed: 04/18/1990
• Issued: 02/11/1992
• Est. Priority Date: 04/28/1989
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Kotobuki
• Original Assignee: Kabushiki Kaisha Kotobuki
• Inventors: Yamazaki, Ryokichi
• Primary Examiner(s): Chen, Jose V.
• Application Number:
  US07/510,525
• Time in Patent Office: 664 Days
• Field of Search: 297/145, 297/162, 297/194, 297/155
• US Class Current: 297/145
• CPC Class Codes: A47C 7/70 of foldable type

Abstract

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

Claims

1. An apparatus for displacing an extensible/contractible board for a chair having an elbow rest in case of an occurrence of emergency, comprising:

a board support for turnably supporting said board, said board support being formed with a bearing hole for rotatably receiving a board shaft made integral with said board, an arcuate recess for turnably receiving an arcuate projection on said board shaft, said arcuate recess being located above said bearing hole, a shaft hole extending at a right angle relative to the board shaft and being located below said bearing hole, and a slide hole for slidably receiving an engagement piece, said slide hole being located at a position behind the shaft hole relative to the board,

an engagement piece slidably received in the slide hole of the base support, said engagement piece having an engagement recess formed thereon so as to allow an eccentric projection on the board shaft to be engaged with said engagement recess,

a turn guide plate disposed adjacent to the board support to guide turning movement of the board and the board support, said turn guide plate being formed with a shaft hole at the central part thereof, an engagement aperture located in alignment with the slide hole of the board support so that a foremost end of the engagement piece is inserted therethrough when the engagement piece is projected outwardly of the board support by turning movement of the board via operative engagement of the eccentric projection of the board shaft with the engagement recess of the engagement piece, an opposing pair of engagement recesses, one of said engagement recesses being located above the shaft hole and the other one being located below the shaft hole, and an arcuate guide groove for allowing the foremost end of the engagement piece to slidably move therealong when the board is turned from a horizontal attitude and thereby the engagement piece is retracted from a projected state via said operative engagement of the eccentric projection of the board shaft with the engagement recess of the engagement piece,

a stationary guide plate having an opposing pair of first engagement projections adapted to be engaged with the engagement recesses of said turn guide plate and an opposing pair of second engagement projections adapted to receive a flange portion of a thrust shaft, said second engagement projections being located opposite to said first engagement projections,

a thrust shaft extending through the shaft hole of said stationary guide plate, the shaft at hole of said turn guide plate, the shaft hole of said board support and a shaft hole of one base member at a right angle relative to the board shaft, said thrust shaft including a flange portion held between the second engagement projections of said stationary guide plate to immovably hold the stationary guide plate, and a male-threaded portion at the fore end part thereof,

an opposing pair of base members firmly secured to the front surface of the foremost end of said elbow rest of the chair with the board support rotatably interposed therebetween, one of said base members being located adjacent to the board support to receive the turn guide plate and the stationary guide plate in a hole formed therein and the other one being likewise located adjacent to the board support with a spring receiving hole formed therein, and

engagement assuring means for firmly holding said board support, said turn guide plate and said stationary guide plate in an operative engagement relationship under the effect of resilient force derived from said engagement assuring means.

2. The apparatus as claimed in claim 1, wherein said engagement assuring means comprises a plurality of Belleville springs for resiliently biasing the board support and the turn guide plate toward the stationary guide plate, said Belleville springs being received in a spring receiving hole of the one base member.

3. The apparatus as claimed in claim 1, wherein said engagement assuring means comprises a solenoid for biasing the board support and the turn guide plate toward the stationary guide plate.

4. The apparatus as claimed in claim 1, wherein each of the engagement projections on the stationary guide plate is contoured in the form of a semicylindrical projection and each of the engagement recesses on the turn guide plate is contoured in the form of a semicylindrical recess.

5. The apparatus as claimed in claim 1, wherein the turn guide plate is formed with another engagement aperture which is located symmetrical to the first-mentioned engagement aperture so as to assure that the apparatus can be used also for other elbow rest of the chair.

6. The apparatus as claimed in claim 1, wherein the stationary guide plate is formed with a cutout with which the foremost end of a set screw comes in contact so that the stationary guide plate is immovably held on the thrust shaft.

7. The apparatus as claimed in claim 1, wherein a depth of the arcuate guide groove of the turn guide plate is determined to coincide with a quantity of retractive displacement of the engagement piece at the time when the board is turned from the horizontal attitude to a vertical attitude.

8. The apparatus as claimed in claim 1, wherein the arcuate projection on the board shaft serves as turning movement limiting means for limiting the range of turning movement of the board from the horizontal attitude to the vertical attitude.

9. The apparatus as claimed in claim 1, wherein the board is received in a hollow space as defined by an opposing pair of sleeve plates when the board is not in use.