Furniture News
Chair
A chair is a piece of furniture for sitting, consisting of a seat, a
back, and sometimes arm rests, commonly for use by one person. Chairs
also often have four legs to support the seat raised above the floor.
Without back and arm rests it is called a stool. A chair for more than
one person is a couch, sofa, settee, loveseat, recliner or bench. A
separate footrest for a chair is known as an ottoman, hassock or
pouffe. A chair mounted in a vehicle or in a theater is simply called
a seat. Chairs as furniture typically can be moved.
The back often does not extend all the way to the seat to allow for
ventilation. Likewise, the back and sometimes the seat are made of
porous materials or have holes drilled in them for decoration and
ventilation
.
History of Chair
The chair is of extreme antiquity, although for many centuries and
indeed for thousands of years it was an article of state and dignity
rather than an article of ordinary use. "The chair" is still
extensively used as the emblem of authority in the House of Commons in
the United Kingdom and Canada, and in public meetings. It was not, in
fact, until the 16th century that it became common anywhere. The
chest, the bench and the stool were until then the ordinary seats of
everyday life, and the number of chairs which have survived from an
earlier date is exceedingly limited; most of such examples are of
ecclesiastical or seigneurial origin. Our knowledge of the chairs of
remote antiquity is derived almost entirely from monuments, sculpture
and paintings. A few actual examples exist in the British Museum, in
the Egyptian Museum at Cairo, and elsewhere.
In ancient Egypt chairs appear to have been of great richness and
splendor[citation needed]. Fashioned of ebony and ivory, or of carved
and gilded wood, they were covered with costly materials and supported
upon representations of the legs of beasts or the figures of captives.
The earliest known form of Greek chair, going back to five or six
centuries BCE, had a back but stood straight up, front and back.
During Tang dynasty (618 - 907 AD), a higher seat first started to
appear amongst the Chinese elite and their usage soon spread to all
levels of society. By the 12th century seating on the floor was rare
in China, unlike in other Asian countries where the custom continued,
and the chair, or more commonly the stool, was used in the vast
majority of houses throughout the country.
In Europe, it was owing in great measure to the Renaissance that the
chair ceased to be a privilege of state, and became a standard item of
furniture whoever could afford to buy it. Once the idea of privilege
faded the chair speedily came into general use. We find almost at once
that the chair began to change every few years to reflect the fashions
of the hour.
The 20th century saw an increasing use of technology in chair
construction with such things as all-metal folding chairs,
metal-legged chairs, the Slumber Chair, moulded plastic chairs and
ergonomic chairs. The recliner became a popular form, at least in part
due to radio and television, and later a two-part. The modern movement
of the 1960s produced new forms of chairs: the butterfly chair, bean
bags, and the egg-shaped pod chair. Technological advances led to
molded plywood and wood laminate chairs, as well as chairs made of
leather or polymers. Mechanical technology incorporated into the chair
enabled adjustable chairs, especially for office use. Motors embedded
in the chair resulted in massage chairs.
Design of Chair
Chair design considers intended usage, ergonomics (how comfortable
it is for the occupant), as well as non-ergonomic functional
requirements such as size, stack ability, fold ability, weight,
durability, stain resistance and artistic design. Intended usage
determines the desired seating position. "Task chairs", or any chair
intended for people to work at a desk or table, including dining
chairs, can only recline very slightly; otherwise the occupant is too
far away from the desk or table. Dental chairs are necessarily
reclined. Easy chairs for watching television or movies are somewhere
in between depending on the height of the screen.
Ergonomic designs distributes the weight of the occupant to various
parts of the body. A seat that is higher results in dangling feet and
increased pressure on the underside of the knees ("popliteal fold").
It may also result in no weight on the feet which means more weight
elsewhere. A lower seat may shift too much weight to the "seat bones"
("ischial tuberosities").
A reclining seat and back will shift weight to the occupant's back.
This may be more comfortable for some in reducing weight on the seat
area, but may be problematic for others who have bad backs. In
general, if the occupant is suppose to sit for a long time, weight
needs to be taken off the seat area and thus "easy" chairs intended
for long periods of sitting are generally at least slightly reclined.
However, reclining may not be suitable for chairs intended for work or
eating at table.
an adjustable office chair The back of the chair will support some of
the weight of the occupant, reducing the weight on other parts of the
body. In general, backrests come in three heights: Lower back
backrests support only the lumbar region. Shoulder height backrests
support the entire back and shoulders. Headrests support the head as
well and are important in vehicles for preventing "whiplash" neck
injuries in rear-end collisions where the head is jerked back
suddenly. Reclining chairs typically have at least shoulder height
backrests to shift weight to the shoulders instead of just the lower
back.
Some chairs have foot rests. A stool or other simple chair may have a
simple straight or curved bar near the bottom for the sitter to place
his/her feet on.
A kneeling chair adds an additional body part, the knees, to support
the weight of the body. A sit-stand chair distributes most of the
weight of the occupant to the feet. Many chairs are padded or have
cushions. Padding can be on the seat of the chair only, on the seat
and back, or also on any arm rests and/or foot rest the chair may
have. Padding will not shift the weight to different parts of the body
(unless the chair is so soft that the shape is altered). However,
padding does distribute the weight by increasing the area of contact
between the chair and the body. A hard wood chair feels hard because
the contact point between the occupant and the chair is small. The
same body weight over a smaller area means greater pressure on that
area. Spreading the area reduces the pressure at any given point. In
lieu of padding, flexible materials, such as wicker, may be used
instead with similar effects of distributing the weight. Since most of
the body weight is supported in the back of the seat, padding there
should be firmer than the front of the seat which only has the weight
of the legs to support. Chairs that have padding that is the same
density front and back will feel soft in the back area and hard to the
underside of the knees.
There may be cases where padding is not desirable. For example, in
chairs that are intended primarily for outdoor use. Where padding is
not desirable, contouring may be used instead. A contoured seat pan
attempts to distribute weight without padding. By matching the shape
of the occupant's buttocks, weight is distributed and maximum pressure
is reduced.
ChurchchairsActual chair dimensions are determined by measurements of
the human body or anthropometric measurements. Individuals may be
measured for a custom chair. Anthropometric statistics may be gathered
for mass produced chairs. The two most relevant anthropometric
measurement for chair design is the popliteal height and buttock
popliteal length.
For someone seated, the popliteal height is the distance from the
underside of the foot to the underside of the thigh at the knees. It
is sometimes called the "stool height". (The term "sitting height" is
reserved for the height to the top of the head when seated.) For
American men, the median popliteal height is 16.3 inches and for
American women it is 15.0 inches. The popliteal height, after
adjusting for heels, clothing and other issues is used to determine
the height of the chair seat. Mass produced chairs are typically 17
inches high.
For someone seated, the buttock popliteal length is the horizontal
distance from the back most part of the buttocks to the back of the
lower leg. This anthropometric measurement is used to determine the
seat depth. Mass produced chairs are typically 38-43 cm deep.
The Difference between Leg Room & Seat PitchAdditional anthropometric
measurements may be relevant to designing a chair. Hip breadth is used
for chair width and armrest width. Elbow rest height is used to
determine the height of the armrests. The buttock-knee length is used
to determine "leg room" between rows of chairs. "Seat pitch" is the
distance between rows of seats. In some airplanes and stadiums the leg
room (the seat pitch less the thickness of the seat at thigh level) is
so small that it is sometimes insufficient for the average person
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