BIONIC POSTURE CORRECTING FRAME FOR LEANING ON IN STUDY

The invention relates to a bionic and posture-correcting backrest for study, and more particularly to a bionic and posture-correcting backrest for study for primary school students.

Nowadays, an increasing number of primary school students and middle school students are suffering from short-sight and hunchback. Thus, to develop a posture-correcting backrest for study is a consensus and requirement from people all over the world.

There are many causes for such unhealthy tendency and the results are serious. From the perspective of school hygiene, "forward sitting position" is defined if a person's upper body gravity is right on or in the front of the ischiatic tuberosity, where the balance is maintained by the back muscles and thighs. "Backward sitting position" is defined if a person's upper body gravity is behind the ischiatic tuberosity, where the back must be against the backrest. It is apparent that the forward sitting position is likely to cause fatigue while the backward sitting position is not. However, students are fond of using the forward sitting position to study by bending over the desks. From the perspective of the physiology, when your line of sight is perpendicular to the object you are looking at, the image projected onto your retina is the clearest. It is called the "physiological visual angle". Therefore, the students have to look down for the clearest image. From the perspective of the biology, human bones are made up of hard and fragile inorganic composition and flexible organic composition. The physical properties of bones are hardness and flexibility. The content of different composition and the physical properties of bones vary with age. For example, teenagers' bones are less hard but more flexible and elastic; therefore they are unlikely to be fractured but likely to be deformed. If students do not pay more attention on their sitting position when they study, they would suffer from hunchback, scoliosis or short-sight. Liu Zhiming, the attending physician in Beijing Puren Hospital (previously Beijing No. 4 Hospital), finds out after many years research that if teenagers pay less attention on their sitting position when they study, they are more likely to suffer from fatigue, short-sight and hunchback. An even more serious consequence is that they are at considerably higher risk of contracting cervical spondylosis after growing up.

However, this unhealthy phenomenon has not been deeply realized. On the one hand, students like to use the forward sitting position to study by bending over the desks, they have not been aware of the function of the backward sitting position. On the other hand, some students partially lay great emphasis on backward sitting position, they have not been aware of the importance of the forward sitting position and not recognized such position can be necessary and corrected. But in fact, if there is no "forward sitting position", Chinese traditional brush cannot be used properly. The backward sitting position, as a sitting position contrary to the forward sitting position, also has the problem that students study by bending over the desks. In addition, the forward sitting position and the backward sitting position, as two basic positions, can be freely switched. During the switch, there are other optional positions because people cannot sit with only one position. All the positions are contributable to correct sitting, reading, writing, and listening, i.e. a fist distance between chest and edge of desk and a foot from eyes to books. In this way, the fingertip can be an inch from the pen point while the head and body can remain straight.

To solve the above problems, some measures have been taken but with poor results. With respect to the backrest, related devices have been invented to prevent short-sight and hunchback. They have effects to some extent but still have the following problems. The conventional adjustable support is the sternal plate. The lower end of the sternal plate is not connected with the ventral plate and the abdomen is not supported. When students are in study, their waists are likely to bend and their bodies are likely to move downwards. In addition, under normal circumstances, sitting tools do not have backrests, if they have, the backrests are mostly fixed. Even if the backrests are moveable forwards and backwards, they are not fit with the conventional adjustable support, therefore, the external condition for study with the correct sitting position is not achieved.

In view of the above-described problems, it is one objective of the invention to provide a bionic and posture-correcting backrest for study, which matches with desks and chairs, especially the bionic and posture-correcting desks and chairs. It allows users to maintain the correct "forward sitting position" and the "backward sitting position" or any sitting position therebetween all the time. The sitting position can be easily adjusted and it is unlikely to cause fatigue.

To achieve the above objective, in accordance with one embodiment of the invention, there is provided a bionic and posture-correcting backrest for study, comprising a bracket body disposed at the rear of the desk via a mounting rack, wherein an adjustable element is provided on a frame which is between the chest/abdomen and the desk edge as well as between the chin and lower part of abdomen (slightly above the thighs); the adjustable element is a fist distance away from the desk edge if a user sits on the chair with the correct sitting position. In this way, the "forward sitting position" and the "backward sitting position" or any sitting position therebetween can be achieved and meanwhile freely switched. The bracket body comprises at least one adjustable tubular pile and a pectoral/ventral plate. The pectoral/ventral plate is moveably connected with an upper adjustable plate. Inside of the adjustable tubular pile is sheathed with a chin adjustment element, which is used to adjust the height of a chin rest. The mounting rack is an adjustable plate cover or an adjustable collar.

The adjustable element is that the bracket body comprises the pectoral/ventral plate and 1-3 adjustable tubular pile(s) whose inside is sheathed with adjustable tubes. The length of the adjustable element equals to the distance between two points with one from the upper end of the chest to the lower part of the abdomen and the other one from the lower end of the bracket body to the upper side of the thighs, the width of the adjustment element equals to the distance between two points with one at 2.5 cm in the middle of the left and right chest and the other one is the two sides of the chest. The upper end of the adjustable tubular pile is sheathed with a pad cover comprising a reversed pin. Inside of the pad cover is sheathed with a first adjustable tube. The lower end of the first adjustable tube is sheathed with a first adjustable pin, which is larger than the adjustable tube and fits with the adjustable tubular pile. The upper end of the first adjustable tube sheathed with the chin rest. The chin rest comprises a chin pad, a frame cover, a button plate, a spring and a frame base that are sheathed with one another. A button on the button plate extends out of an aperture of the chin pad. A sleeve of the button plate is sheathed on the upper end of a connecting rod. A follow block that is attached to the lower end of the connecting rod is against by the adjustable arm at one side of the upper end of the first adjustable pin. A transverse shaft inside the adjustable groove under the adjustable arm fixes the first adjustable pin to the two walls of one side of the first adjustable tube. The lower end of the adjustable arm is against by a spring of a base plate of the adjustable tubular pile. The lower part of the adjustable arm is in the shape of a "Z" and is sheathed with the pin block, whose one side comprises an inclined recess and whose one end is the pin head. The pin block is disposed in a pin room. On the adjustable tubular pile at one side of the pin head of the first adjustable pin is disposed from top to bottom with the equidistant positional adjustment holes. Inside of the upper end of the first adjustable tube is sheathed with the pad cover for the reversed pin. Inside of the pad cover is sheathed with the second adjustable tube and a second adjustable pin at the lower end. The upper end of the second adjustable tube is covered by the chin rest. The lower end of the second adjustable pin is against by the upper end of the adjustable arm of the first adjustable pin at the other side. When the second and the first adjustable tubes slide to the base plate of the adjustable tubular pile, the pin head of the second adjustable tube, adjacent to one side of the adjustable arm of a second adjustable pin, passes through the first adjustable tube and one aperture of the adjustable tubular pile. When the first adjustable tube is pulled to its limit to the corresponding position of the upper part of the adjustable tubular pile, on the other side, the pin head of the first adjustable pin passes through one aperture of the adjustable tubular pile. On the first adjustable tube of one side of the pin head of the second adjustable pin of the second adjustable tube is disposed with positional adjustment holes from top to bottom. The upper end of the adjustable groove of another adjustable arm is reversely disposed with the spring. The spring is placed on a block that is extended from the wall of the adjustable pin. Another adjustable arm extends downwards with an inclined foot that is sheathed with an inclined aperture of another pin block and a circular pin is used to connect the adjustable tubes as a whole. At the front of the adjustable tubular pile and the pectoral plate is moveably connected with an upper adjustable plate in the transversal direction. The width of the upper adjustable plate equals to the width of the pectoral plate and the length of the upper adjustable plate equals to the distance of the fist (to the desk) plus the part in the mounting bracket. The two sides of the upper adjustable plate are disposed with recesses that fit with a moveable pin of the mounting bracket. The mounting bracket is reversely disposed at the bottom of the desktop. The adjustable plate cover of the mounting bracket comprises an upper plate and a base plate. The top two ends and the front end of the upper plate are each connected with a baffle and disposed with the moveable pins. The moveable pin is smaller than the pin mouth. Inside of the moveable pin is disposed with an adjustable plate cover pin head. The rear side of the adjustable plate cover pin head is against a spring. Inside of the upper plate of the moveable pin is disposed with arc-shaped leaf springs. On the upper adjustable plate is disposed with recesses that fit with the arc-shaped leaf springs. Furthermore, the base plate may also be one of the top/bottom surfaces of the desktop or the mounting plate. Both ends of the chin pad are disposed strings, one end thereof connected with a hanging pole, which fixes the chin pad to a padding plate protruding forward from the end of an adjustable column.

The button is sheathed below the chin rest. The chin rest of the adjustable tube comprises a chin pad, another button plate, and lever arms. The chin rest is sheathed at the upper end of the two adjustable tubes. The upper ends of the two lever arms pass through the apertures at the opposite inner sides of the two adjustable tubes to moveably connect with the upper end of the connecting rod, respectively. The apertures at the upper ends of the two lever arms are moveably connected with the transverse shafts on the chin rest. The upturned sides at the lower ends of the two lever arms are inserted into the bottom of a connecting groove, which is reversely disposed in the chin rest and which is on another button plate. Another button plate is hanged on the two lever arms via hanging rods at the front and back of the connecting groove. The chin rest of the adjustable tube comprises a chin pad and another lever arm. The chin rest is sheathed on the upper end of the adjustable tube. The aperture at the upper end of another lever arm is moveably connected with the transverse shaft, which is at the other side of the connecting tube and which is on the adjustable tube. The lower end of another lever arm is at the other side of the adjustable tube to inclinedly extend to the bottom of the chin rest. The upper end of the first adjustable tube is covered by the chin pad and the lower end of the first adjustable tube is sheathed with a first adjustable pin, which is bigger than the first adjustable tube and which fits with the adjustable tubular pile. The two adjustable pins are parallelly connected with each other to form an adjustable pin. The pin head of the adjustable pin can face one side or face both sides. On the pin head of the adjustable pin and on the adjustable tubular pile are disposed with positional adjustment holes from top to bottom. On one side of the pin head, a side button is extended from the adjustable groove of the adjustable tubular pile. The side button comprises an upper button block and a lower button block. The upper button block and the lower button block are respectively at one side of the first adjustable tube to connect with the upper end of the adjustable arm and the lower outer side of the first adjustable pin. One side of the external adjustable tubular pile is connected with the upper/lower ends of an upper circular tube and a lower circular tube that are sheathed with the spring. The upper button block and the lower button block of the two adjustable tubular piles are transversally connected as a whole.

The bracket body comprises 1-3 adjustable tubular pile(s), whose inside is sheathed with adjustable tubes and which combines with the pectoral plate. The length of the adjustable element equals to the distance of two points with one from the upper end of the chest to the lower part of the abdomen and the other one is from the lower end of the bracket body to the upper side of the thighs, the width of the adjustment element equals to the distance of two points with one at 2.5 cm in the middle of the left and right chest or the sternal plate is narrow but the ventral plate has the same width as the abdomen. The upper end of the adjustable tubular pile is connected with the chin rest. The other three sides of the adjustable tubular pile form the frame edge. From the middle point of the left and right frame edges extends downwards with a section. An acute angle triangle (the top is the acute angle and the bottom becomes thicker) is formed from the middle point of such section to separate the adjustable column into a rear plate and a front plate. One surface of the rear plate becomes thinner to zero along the rear plate of the adjustable tubular pile while one surface of the front plate becomes thinner along the front plate of the adjustable tubular pile to be the gear head and fit with the positional adjustment gears. The rear side of the front plate of the adjustable column on the gear head passes through the front side and extends with a rectangle button underframe in the transversal direction, which fits with the adjustable groove of the adjustable tubular pile. The button underframe matches with the reversed pin of another button. Another buttons on the two adjustable tubular piles can be transversally connected as a whole. At the connection point between the ventral plate and the sternal plate is moveably connected with an upper adjustable plate. The left and right ends of the upper adjustable plate are disposed with equidistant positional adjustment gears, which fit with the mounting bracket. A bracket position correction element is disposed between the upper adjustable plate and the pectoral plate. The adjustable cover of the mounting bracket comprises a cover plate, a median plate, a base plate, a wheel, a moveable plate, adjustable cover pin blocks, the spring and another handle. On the opposite side of the wheel is respectively disposed with a column. On the one side of the two adjustable cover pin blocks is respectively disposed with the column. The apertures at the two ends of the two moveable plates are moveably connected with wheel and the columns of the two adjustable cover pin blocks. The other side of the adjustable cover pin blocks is against the spring. The above structure fits with the space formed by the median plate and the cover plate. One side of the two adjustable cover pin blocks passes through the median plate and the adjustable groove of the inner side of the baffle with a section. The two adjustable cover pin blocks is extendable along the adjustable groove. The median plate, the baffle, and the base plate form a transversal gap. The shaft on the wheel passes through the aperture of the cover plate to connect with another handle via bolts.

At the front of the lower end of the adjustable column and at two sides of another button are respectively disposed with a gear head(s), which matches with positional adjustable gear at the front of the adjustable tubular pile. The lower end of the adjustable column is disposed with a bow-shaped leaf spring. A bow point of the bow-shaped leaf spring is against the inner side of the rear wall of the adjustable tubular pile. The adjustable column is the adjustable tube. The lower end of the adjustable tube is disposed with the bow-shaped leaf spring. The bow point of the bow-shaped leaf spring is disposed with another button, which extends out of the adjustable groove at the front of the adjustable tube. The bow points at two sides of another button are respectively disposed with the pin head. The pin head is sheathed with the positional adjustment holes at the front wall of the adjustable tubular pile. Inside of the lower end of the adjustable tube is sheathed with an inner sleeve adjustable pin. The inner sleeve adjustable pin is between pin slices that are moveably connected at the lower end of the adjustable tube and transversally supports the spring. The pin slices have one side relative to the spring respectively disposed with a double button. The two buttons extend out of the left and right adjustable grooves of the adjustable tubular pile. The gear head that is projected from the lower ends (relative sides) of the two pin slices matches with the positional adjustment gear from top to bottom at the inner side of the adjustable groove.

Inside of the adjustable tubular pile is sheathed with the adjustable column, extending from the chest to the lower part of the abdomen and the upper side of the thighs. The chin pad is at the place where the upper end (end portion) of the adjustable column extends forwards at 90°. The bottom of the upper end of the adjustable column is disposed with another chin adjustment element. The chin adjustment element comprises a cover plate, a front plate of the pectoral plate (equivalent to the median plate), a rear plate of the pectoral plate (equivalent to the base plate), a wheel, moveable plates, the adjustable cover pin blocks, the spring and another handle. The front plate and the rear plate form a vertical gap therebetween. The adjustable cover pin blocks at the left and right of the vertical gap match with the adjustable column having the equidistant positional adjustment gears. The shaft on the wheel extends out of the aperture of the cover plate and is fixed with another handle. The column extending out of the opposite side of the shaft is placed in the aperture at the front of the rear plate via the adjustable groove of the adjustable column. In the middle of the front and rear sides of the pectoral plates that are at the left and right sides of the adjustable tubular pile is disposed with a flat gap extending to the left and right sides. At the upper and lower sides of the flat gap are moveably connected with a moveable pectoral plate, respectively. The moveable pectoral plate uses the moveable connecting point as the start point and has the same distance at the left, right and top. Between the moveable pectoral plate and the pectoral plate is covered by a boss. The moveable pectoral plate is moveable by 90° between flat and stand positions. The inner side of the upper end of the adjustable tubular pile is slightly small and is sheathed with the adjustable column for a vertical cap nut. The adjustable column has a small upper section and big lower section and is moveably sheathed with a bolt. The lower end of the bolt is connected with the upper end of an arc-shaped boss. The lower end of the arc-shaped boss is connected with a knob that can be transversally rotated. The lower end of the arc-shaped boss can also be connected with umbrella-shaped gears. The umbrella-shaped gears are sheathed with the umbrella-shaped gears at the two ends of the knob which is rotatable in the vertical direction. The knob is disposed at the two sides or middle of the lower ends of the adjustable tubular piles.

The sternal plate of the bracket body is long and the chin adjustment element is disposed on the sterna plate to divide the bracket body horizontally into upper and lower sections. The intersection point of the two sections is disposed with a hinge. The left and right ends of the pectoral plate are each disposed with a connecting tubular pile. The left/right sides and the three edges of the connecting column in the connecting tubular pile of the sternal plate are the frame edge. The lower side extends upward with a gear head (pin head), which fits with the positional adjustment gear (positional adjustment hole) of the connecting tubular pile. The lower part of the gear head is connected with a handle extending out of a connecting groove. The connecting column is moveable ups and downs.

On the bracket body is disposed with a ventral plate adjustment element. The ventral plate adjustment element shortens the ventral plate by three tenths. The adjustable tubular piles are disposed at the left and right sides of the ventral plate. At the lower end of the ventral plate is disposed with a lower crossbeam, which aligns to the width of the ventral plate. The upper end of the lower crossbeam is perpendicularly connected with the lower end of the adjustable column in the adjustable tubular pile. The positional adjustment holes and bolts are disposed between the adjustable tubular pile and the lower adjustable column. At the front of the lower crossbeam is moveably connected with the lower adjustable plate. The lower end of the ventral plate is disposed with another lower crossbeam. Another lower crossbeam is behind the adjustable tubular pile and is formed by left and right crossbeams. On the side between another lower crossbeam and the adjustable tubular pile is covered by bosses from top to bottom. The upper end of another lower crossbeam is connected with the lower end of the adjustable column of the adjustable tubular pile. The left and right frames of the adjustable column and the top three surfaces form the frame edge; the lower surface extends upwards with a turned gear head. The gear head can be sheathed on the upper or lower equidistant positional adjustment gears of the adjustable tubular pile. At the lower side of the positional adjustment gear is connected with the handle, extending out of the adjustable groove. The connecting column is moveable up and down. At the lower end at the front of the bracket body is moveably connected with a lower adjustable plate. The width of the lower adjustable plate equals to the width of the upper adjustable plate and the length of the lower adjustable plate equals to the distance of the fist (to the desk) plus the element that cooperates with the adjustable base plate (desktop lifting element) and which can adjust the frame to decline forwards and backwards. At the rear of the lower adjustable plate and adjacent to the front of the adjustable tubular pile is disposed with a convex button hole. Between the front end of the lower adjustable plate and the adjustable base plate is disposed with a magnet.

At the lower end at the front of the ventral plate is moveably connected with a lower adjustable plate. The width of the lower adjustable plate equals to the width of the upper adjustable plate and the length of the lower adjustable plate equals to the distance of the fist (to the desk) plus the element that cooperates with the adjustable base plate (desktop lifting element). At the rear of the lower adjustable plate and adjacent to the front of the adjustable tubular pile is disposed with a convex button hole. Between the lower adjustable plate and the adjustable base plate is disposed with a magnet, bolt, positional adjustment holes, and adjustable grooves.

A clamp structure is applied for the adjustable plate cover and the adjustable cover. The clamp comprises a mounting bracket follow block, a mounting plate, a connecting plate, fastening bolt, and follow block. The mounting bracket follow block and the mounting plate are connected by the connecting plate. One end of the fastening bolt passes through the mounting plate and is sheathed with the follow block. At the opposite sides of the mounting bracket follow block and the follow block can be sheathed with a rubber padding plate. The clamp is moveable. It divides the connecting plate into upper and lower sections. The lower section, long and narrow, connects one side of the mounting bracket follow block and is disposed with the adjustable groove from top to bottom. The upper section, short and wide, connects one side of the mounting plate and at the overlapped side with the lower section is disposed with a clamp groove from top to bottom, which fits with the connecting plate. A bolt extending out of the lower end of the clamp groove passes through the adjustable groove to engage with a butterfly cap nut.

The frame comprises the bracket body and the mounting rack.

Advantages of the invention are summarized below: 1. the effect is significant and immediate. Bionic principle is adopted in the invention. The ventral plate and the upper adjustable plate are added. The pectoral plate and the upper adjustable plate are moveably connected to sallow the chest and abdomen to lean forwards or backwards. The mounting bracket is used to adjust the distance between the chest and abdomen to the desk edge. The chin adjustment element is improved. It can be freely adjusted and hold the chin. The chin adjustment element is suitable for any desk and chair. If the bionic and posture-correcting backrest is equipped with such chin adjustment element, a reasonable space will be formed between the head, eyes, neck, chest, abdomen, waist, back, buttocks, elbows, legs, feet and the desk and chair. Users will always be at the correct "forward sitting position" or "backward sitting position" or any position in Between. The problem that students study by bending over the desks is solved. In addition, the position can be changed at will and students will not easily fatigue. It saves large amount of time for teaching and study, and 2. The bionic and posture-correcting backrest for study provided by the invention is easy to be used, stored and carried. Users are only required to press buttons or turn the handle to use the bionic and posture-correcting backrest. It is only necessary to tighten the bolts when clamps or movable clamps are used. The bracket body is disposed with the ventral plate adjustment element, which can be used on different desks. The bracket body folding element functions to fold the bracket body. Furthermore, the clamps or moveable clamps can connect the adjustable plate cover with the bracket body. The above elements or structure make it convenient for users to carry the bionic and posture-correcting backrest.

The invention is explained in further detail below with reference to the embodiments and attached drawings.

FIG. 1 is a front view of a bracket body in accordance with a first embodiment of the invention (the moveably connected upper adjustable plate and the lower adjustable plate are horizontally disposed);

FIG. 2 is a front view of the bracket body of FIG. 1 in accordance with another embodiment of the invention;

FIG. 3 is a front view of the bracket body of FIG. 1 in accordance with another embodiment of the invention;

FIG. 4 is a front view of a chin adjustment element of FIG. 1, which is drawn to its maximum limit;

FIG. 5 is a front view of the chin adjustment element of FIG. 2, which is drawn to its maximum limit;

FIG. 6 is a front view of the chin adjustment element of FIG. 3, which is drawn to its maximum limit;

FIG. 7 is a front view of the bracket body of FIG. 1 in accordance with another embodiment of the invention;

FIG. 8 is a rear view of the bracket body of FIG. 7;

FIG. 9 is a front view of the bracket body of FIG. 2 in accordance with another embodiment of the invention;

FIG. 10 is a front view of the bracket body of FIG. 3 in accordance with another embodiment of the invention;

FIG. 11 is a vertically sectional front view of an adjustable tubular pile internally sheathed with an adjustable tube and an adjustable pin of FIGS. 1-10;

FIG. 12 is a side schematic diagram of the adjustable tubular pile of FIG. 11;

FIG. 13 is an exploded front view of a chin rest of FIGS. 1-10;

FIG. 14 is an exploded front view of another chin rest of FIG. 13;

FIG. 15 is a side view of the bracket body of FIG. 1 after being collapsed;

FIG. 16 is a vertically sectional front view of another adjustable pin of FIG. 11;

FIG. 17 is a side view of the frame mounted on a desk of FIG.1;

FIG. 18 is a top view of an upper adjustable plate of the invention;

FIG. 19 is a top view of another upper adjustment plate of FIG. 18;

FIG. 20 is a side view of a chin pad of the invention;

FIG. 21 is a front view of the chin pad of the invention;

FIG. 22 is a top view of another chin pad of the invention;

FIG. 23 is a rear view of an adjustable plate cover of the invention;

FIG. 24 is a top view of the adjustable plate cover of FIG. 23;

FIG. 25 is a rear view of the adjustable plate cover of FIG. 23 in accordance with another embodiment of the invention;

FIG. 26 is a top view of the adjustable plate cover of FIG. 25;

FIG. 27 is a vertically sectional front view of another double-post chin rest of the invention;

FIG. 28 is a vertically sectional front view of another single-post chin rest of the invention;

FIG. 29 is a vertically sectional front view of another adjustable tubular pile internally sheathed with an adjustable tube and the adjustable pin of FIG. 11;

FIG. 30 is a side schematic diagram of the adjustable tubular pile of FIG. 29;

FIG. 31 is a vertically sectional front view of another embodiment of FIG. 29;

FIG. 32 is a side view of the adjustable tubular pile of FIG. 31;

FIG. 33 is a front view of the bracket body in accordance with embodiment 2 of the invention (the moveably connected upper adjustable plate and the lower adjustable plate are horizontally disposed);

FIG. 34 is a front view of the bracket body of FIG. 33 in accordance with another embodiment of the invention;

FIG. 35 is a front view of the bracket body of FIG. 33 in accordance with another embodiment of the invention;

FIG. 36 is a front view of the declined upper adjustable plate of FIG. 35.

FIG. 37 is a front view of the upturned upper adjustable plate of FIG. 36;

FIG. 38 is a rear view of the bracket body of FIG. 35;

FIG. 39 is a vertically sectional side view of the adjustable tubular pile internally sheathed with an adjustable column of FIG. 35;

FIG. 40 is a top view of a button of FIG. 39;

FIG. 41 is a sectional side view of the button of FIG. 39;

FIG. 42 is a front view of the adjustable column of FIG. 39;

FIG. 43 is a vertically sectional side view of the adjustable column of FIG. 39 in accordance with another embodiment of the invention;

FIG. 44 is a vertically sectional side view of the adjustable column of FIG. 39 in accordance with another embodiment of the invention;

FIG. 45 is a front view of the adjustable tubular pile of FIGS. 39, 43 and 44;

FIG. 46 is a vertically sectional side view of the adjustable tubular pile internally sheathed with the adjustable column of FIGS. 33-35 in accordance with another embodiment of the invention;

FIG. 47 is a front view of the adjustable tubular pile of FIG. 46;

FIG. 48 is a vertical sectional view of another adjustable column of FIGS. 46-47;

FIG. 49 is a structural representation of the upside of an adjustable collar of the invention;

FIG. 50 is a structural representation of the rear side of the adjustable collar of FIG. 49;

FIG. 51 is a top view of a median plate of the adjustable collar of FIG. 49;

FIG. 52 is a bottom view of a cover plate of the adjustable collar of FIG. 49;

FIG. 53 is a top view of an adjustable collar locking block and a spring of FIG. 51;

FIG. 54 is a front view of the adjustable column of FIG. 35 in accordance with another embodiment of the invention;

FIG. 55 is a vertically sectional front view of a chin adjustment element of FIG. 54;

FIG. 56 is a vertically sectional rear view of the chin adjustment element of FIG. 54;

FIG. 57 is a front view of an unfolded moveable pectoral plate of another bracket body of FIG. 54;

FIG. 58 is a front view of the collapsed moveable pectoral plate of the bracket body of FIG. 57;

FIG. 59 is a front view of the bracket body of FIG. 33 in accordance with another embodiment of the invention;

FIG. 60 is a front view of the bracket body of FIG. 35 in accordance with another embodiment of the invention;

FIG. 61 is a vertically sectional front view of the chin adjustment element of FIG. 60;

FIG. 62 is a vertical sectional view of the chin adjustment element of FIG. 59;

FIG. 63 is a side view of a clamp of the invention;

FIG. 64 is a side view of a moveable clamp of the invention; and

FIG. 65 is a rear view of the moveable clamp of FIG. 64.

FIGS. 1-32 show a first embodiment of the invention. The frame comprises a bracket body and a mounting bracket 41. As shown in FIGS. 1-10, the bracket body comprises 1-2 adjustable tubular pile (s) 25 and a pectoral/sternal plate 29. The length of the bracket body equals to the distance from the upper end of the chest to the lower part of the abdomen (slightly above the thighs) and the width of the bracket body is 2.5 cm from the left/right chest to the two sides of the chest. The upper end of the bracket body is defined from the upper end of the chest to any point of the desk edge (where the chest and abdomen meet) while the lower end of the bracket body is defined from the desk edge to the lower part of the abdomen (bottom of the desk) and to any point above the thighs. The width is 2.5 cm from the left/right chest to any point between the two sides of the chest. As shown in FIGS. 9 and 10, a sternal plate 30 is narrow and a ventral plate 31 is wide. As shown in FIG. 1, the upper end of the bracket body is parallel to the upper end of the chest and the adjustable tubular pile 25 is disposed on the sternal plate 30. As shown in FIG. 2, the upper end of the bracket body is between the upper and lower parts of the chest and the adjustable tubular pile 25 is disposed from the upper end to the lower end of the sternal plate 30. As shown in FIGS. 1-2, inside of the adjustable tubular pile 25 is only disposed with a first adjustable tube 24. As shown in FIG. 3, the upper end of the bracket body is at the connection point between the chest and the abdomen, the adjustable tubular pile 25 is disposed on the ventral plate 31 from top to bottom, and inside of the adjustable tubular pile 25 is disposed with the first adjustable tube 24 and a second adjustable tube 24. The FIGS. 7-10 show the similar structure as the FIGS. 1-3, the difference is that the adjustable tubular pile 25 has a single column and no ventral plate adjustment element. As shown in FIGS. 2-3, 5-6 and 9-10, two sides of the adjustable tubular pile 25 of the sternal plate 30 can be omitted. Certainly, the bracket body may also be in the shape of a frame, which is formed by two or three adjustable tubular piles 25 that are transversely connected by connecting plates or connecting tubes therebetween. As shown in FIGS. 1-10, the bracket body is provided with a chin adjustment element. The chin adjustment element is at the upper end of the adjustable tubular pile 25 and is sheathed with a pad cover 32 for a reversed pin 87. Inside of the pad cover 32 is sheathed with the first adjustable tube 24. Inside of the lower end of the first adjustable tube 24 is sheathed with a first adjustable pin 27 ("adjustable pin 27"), which is slightly bigger than the first adjustable tube 24 and which fits with the adjustable tubular pile 25. The adjustable pin 27 comprises an adjustable arm 12, an adjustable groove 13, a pin block 20, a pin head 17 that is between the adjustable tubular piles 25, positional adjustment holes 22 and a spring 5. As shown in FIG. 13, the upper end of the first adjustable tube 24 is covered by a chin rest 1. The chin rest 1 comprises a chin pad 2, a frame cover 3, a button plate 4, the spring 5 and a frame base 7 that are sheathed with one another. A button 6 on the button plate 4 extends out of an aperture 8 that is at one side of the chin pad 2 on the frame cover 3.As shown in FIG. 14, the button 6 extends out of the aperture 8 that is under the chin pad 2 supported on the frame cover 3. As shown in FIGS. 11-14, a sleeve 9 of the button plate 4 is sheathed on the upper end of a connecting rod 10. A follow block 11 that is attached to the lower end of the connecting rod 10 is against by the adjustable arm 12 at one side of the upper end of the first adjustable pin 27. A transverse shaft 14 inside the adjustable groove 13 under the adjustable arm 12 fixes the first adjustable pin 27 to the two walls of one side of the first adjustable tube 24. The lower end of the adjustable arm 12 is against by a base plate 78 of the adjustable tubular pile. The lower part of the adjustable arm 12 is in the shape of a "Z" and is sheathed with the pin block 20, whose one side comprises an inclined recess 16 and whose one end is the pin head 17 (gear head 18). The pin block 20 is disposed in a pin room 21. On the adjustable tubular pile 25 at one side of the pin head 17 of the first adjustable pin 27 is disposed from top to bottom with the positional adjustment holes 22 (positional adjustment gears 23 in the inner side) at equal intervals. As shown in FIGS. 3, 6 and 10, inside of the upper end of the first adjustable tube 24 is sheathed with the pad cover 32 for the reversed pin 87. Inside of the pad cover 32 is sheathed with the second adjustable tube 24 and a second adjustable pin at the lower end. The upper end of the second adjustable tube 24 is covered by the chin rest 1. The lower end of the second adjustable pin is against by the upper end of the adjustable arm 12 of the first adjustable pin 27 at the other side. When the second and the first adjustable tubes 24 slide to the base plate 78 of the adjustable tubular pile, the pin head of the second adjustable tube 24, adjacent to one side of the adjustable arm 12 of a second adjustable pin, passes through the first adjustable tube 24 and one aperture of the adjustable tubular pile 25. When the first adjustable tube 24 is pulled to its limit to the corresponding position of the upper part of the adjustable tubular pile 25, on the other side, the pin head 17 of the first adjustable pin 27 passes through one aperture of the adjustable tubular pile 25. On the first adjustable tube 24 of one side of the pin head 17 of the second adjustable pin of the second adjustable tube 24 is disposed with positional adjustment holes 22 from top to bottom. As shown in FIGS. 4-6, the first and the second adjustable tubes 24 are moveable with the button 6 and the pin head 17 is extendable and retractable. In addition, as shown in FIG. 16, the upper end of the adjustable groove 13 of another adjustable arm 12 is reversely disposed with the spring 5. The spring 5 is placed on a block 61 that is extended from the wall of the adjustable pin. Another adjustable arm 12 extends downwards with an inclined foot that is sheathed with an inclined aperture of another pin block 20 and a circular pin is used to connect the adjustable tubes 24. As shown in FIGS. 1-10 and 17-19, at the front of the adjustable tubular pile 25 and the pectoral/sternal plate 29 is moveably connected with an upper adjustable plate 34 in the transversal direction. The width of the upper adjustable plate 34 equals to the width of the pectoral/sternal plate 29 and the length of the upper adjustable plate equals to the distance of the fist (to the desk) plus the part in the mounting bracket 41. The two sides of the upper adjustable plate are disposed with recesses that are fit with a moveable pin 95 of the mounting bracket 41. The top of the upper adjustable plate is provided with adjustable scales 57. As shown in FIG. 17 and FIGS. 23-24, the mounting bracket 41 is reversely disposed at the bottom of the desktop 88 (top and bottom of the mounting plate 38). The adjustable plate cover of the mounting bracket 41 comprises an upper plate 85 and a base plate 84. The top two ends and the front end of the upper plate 85 are each connected with a baffle 79. At the opposite sides transverse to the inner sides of the two baffles are disposed with the moveable pin 95. The moveable pin 95 is smaller than the pin mouth. Inside of the moveable pin is disposed with an adjustable plate cover pin head 17 (a round sphere or the front end is the round sphere and the rear end is connected with a round column). The rear side of the adjustable plate cover pin head 17 is against the spring 5. As shown in FIGS. 25-26, inside of the upper plate 85 of the moveable pin 95 is disposed with arc-shaped leaf springs 51. On the upper adjustable plate 34 is disposed with recesses that fit with the arc-shaped leaf springs 51. Furthermore, the base plate 84 may also be one of the top/bottom surfaces of the desktop 88 or the mounting plate. The gap between the pectoral/sternal plate 29 may be in the shape of a honeycomb.

As shown in FIGS. 1 and 4, a handle 15 can be disposed between the adjustable tubular pile 25 and the other elements. The handle may be made with a ventilation function. The pectoral/sternal plate 29 can be made according to the shape of the chest and abdomen. The chin pad 2 is connected with the frame cover 3 (engage with each other, magnetically attract each other or stick together).

As shown in FIGS. 1, 4 and 7-8, the chin adjustment element of the pectoral/ sternal plate 29 is on the sternal plate 30, on which a bracket folding element is disposed. The bracket folding element is slightly above the upper adjustable plate 34 to horizontally separate the bracket body into upper and lower sections. The intersection point of the two sections is disposed with a hinge 59. The left and right ends of the pectoral/sternal plate 29 are each disposed with a connecting tubular pile 62. As shown in FIGS. 42 and 45, the left/right sides and the three edges of the connecting column in the connecting tubular pile 62 of the sternal plate 30 are the frame edge. The lower side extends upward with a gear head (pin head), which fits with the positional adjustment gear (positional adjustment hole) of the connecting tubular pile 62. The lower part of the gear head is connected with a handle 65 extending out of a connecting groove 66. The connecting column is moveable up and drown. The connecting tubular pile 62 and the connecting column can be replaced by a connecting fastener 68 that is disposed at two sides of front/back surface of the pectoral/sternal plate 29, or a concave clamp that is covered on left/right ends of the sternal plate 30, or upper and lower grooves that fit with front/back surface of the ventral plate. As shown in FIG. 15, the frame folds to the front or back to form an integral part with the connecting fastener 68 (magnet).

As shown in FIGS. 1-10 and FIG. 17, at the lower end (slightly at the upper part) at the front of the ventral plate 31 is moveably connected with a lower adjustable plate 35. The width of the lower adjustable plate 35 equals to the width of the upper adjustable plate 34 and the length of the lower adjustable plate 35 equals to the distance of the fist (to the desk) plus the element that cooperates with the adjustable base plate 86 (desktop lifting element) and which can adjust the frame to decline forwards and backwards. Furthermore, the lower adjustable plate 35 may be in the shape of a trapezoid or a triangle. Similar to the FIG. 36, at the rear of the lower adjustable plate 35 and adjacent to the front of the adjustable tubular pile 25 is disposed with a convex button hole 54. Certainly, it is possible for the moveable seat of the lower adjustable plate 35 to be made more convex so as to fold the lower adjustable plate 35 vertically upwards to the button 6. Between the lower adjustable plate 35 and the adjustable base plate 86 (desk base plate) is disposed with a magnet (bolt, positional adjustment holes and adjustable grooves).

As shown in FIGS. 1-6, and 17, a ventral plate adjustment element is disposed on the frame. The ventral plate adjustment element shortens the ventral plate 31. The adjustable tubular piles 25 are disposed at the left and right sides of the ventral plate 31. At the lower end of the ventral plate 31 is disposed with a lower crossbeam 40, which is align to the width of the ventral plate 31. The upper end of the lower crossbeam 40 is perpendicularly connected with the lower end of the adjustable column in the adjustable tubular pile 25. The positional adjustment holes 22 (adjustable grooves) and bolts are disposed between the adjustable tubular pile 25 and the lower adjustable column. At the front of the lower crossbeam 40 is moveably connected with the lower adjustable plate 35.

As an improvement shown in FIGS. 27-32, a reversed button 6 can be sheathed below the chin rest 1. The chin rest 1 of the adjustable tube 24 comprises a chin pad 2, another button plate 4 and lever arms 41. The chin rest 1 is sheathed at the upper end of the two adjustable tubes 24. The upper ends of the two lever arms 41 pass through the apertures at the opposite inner sides of the two adjustable tubes 24 to moveably connect with the upper end of the connecting rod 10, respectively. The apertures at the upper ends (slightly at the lower position) of the two lever arms 41 are moveably connected with the transverse shafts 14 on the chin rest 1. The upturned sides at the lower ends of the two lever arms 41 are inserted to the bottom of a connecting groove 66, which is reversely disposed in the chin rest 1 and which is on another button plate. Another button plate is hanged on the two lever arms 41 via hanging rods 43 at the front and back of the connecting groove 66. As shown in FIG. 28, the chin rest 1 of the adjustable tube 24 comprises a chin pad 2 and another lever arm 41. The chin rest 1 is sheathed on the upper end of the adjustable tube 24. The aperture at the upper end (slightly at the lower position) of another lever arm 41 is moveably connected with the transverse shaft 14, which is at the other side of the connecting tube and which is on the adjustable tube 24. The lower end of another lever arm 41 is at the other side of the adjustable tube 24 to inclinedly extend to the bottom of the chin rest 1. As shown in FIGS. 29-30, the side button 6 is disposed at the lateral side of the adjustable tube 24. The upper end of the first adjustable tube 24 is covered by the chin pad 2 and the lower end of the first adjustable tube is sheathed with a first adjustable pin 27, which is bigger than the first adjustable tube 24 and which fits with the adjustable tubular pile 25. As shown in FIGS. 31-32, the two adjustable pins 27 are parallelly connected with each other to form an adjustable pin 27. The pin head 17 (gear head 18) of the adjustable pin 27 can face one side or face both sides. As shown in FIGS. 29-32, on the pin head 17 of the adjustable pin 27 and on the adjustable tubular pile 25 are disposed with positional adjustment holes 22 (positional adjustment gears 23 in the inner side) from top to bottom. On the lateral side (opposite side) of the pin head 17, a side button is extended from the adjustable groove 13 of the adjustable tubular pile 25. The side button comprises an upper button block 44 and a lower button block 45. The upper button block 44 is at one side of the first adjustable tube 24 to connect with the upper end of the adjustable arm 12. One side of the external adjustable tubular pile 25 is connected with an upper circular tube 47. The lower button block 45 that is at one side of the adjustable tubular pile 25 is connected with the outer side (slightly at the lower position) of the first adjustable pin 27. One side of the external adjustable tubular pile 25 is connected with a lower circular tube 48 that is covered by the upper circular tube 47. The upper circular tube 47 and the lower circular tube 48 are sheathed with a spring 5. The bottom of the button block 44 on the upper circular tube 47 and the lower circular tube 48 is against the upper side of the first adjustable pin 27, the pin head 17 can be contracted within the first adjustable pin 27. The lower and upper ends of the upper circular tube 47 and the lower circular tube 48 are respectively connected with the upper or lower side of the lower button block 45 and the upper button block 44. The first adjustable tube 24 is movable up and down. The upper button block 44 and the lower button block 45 of the two adjustable tubular piles 25 can be transversally connected as a whole.

FIGS. 33-60 show a second embodiment of the invention. The adjustable tubular pile 25 is sheathed with an adjustable column 49. The upper end of the adjustable column 49 is sheathed with the chin rest 1. As shown in FIG. 42, the left and right sides of the lower portion of the adjustable column 49 and the lower three sides form a frame edge 64. From the middle point of the left and right frame edges 64 extends downwards with a section. As shown in FIG. 39, an acute angle triangle (the top is the acute angle and the bottom becomes thicker) is formed from the middle point of such section to separate the adjustable column 49 into a rear plate and a front plate. One surface of the rear plate becomes thinner along the rear plate of the adjustable tubular pile 25 while one surface of the front plate becomes thinner along the front plate of the adjustable tubular pile 25 to be the gear head 18 (pin head 17) and fit with the positional adjustment gears 23 (positional adjustment hole 22). The rear side of the front plate of the adjustable column 49 on the gear head 18 passes through the front side and extends with a rectangle button underframe 89 in the transversal direction, which fits with the adjustable groove 13 of the adjustable tubular pile 25. The button underframe 89 matches with the reversed pin 87 of another button 6 as shown in FIGS. 40-41. Certainly, the rear plate of the adjustable column 49 may be in the shape of an arc. As shown in FIGS. 33-34, another buttons 6 on the two adjustable tubular piles 25 can be transversally connected as a whole. As shown in FIGS. 35-37, the upper adjustable plate 34 is moveably connected with the front side of the adjustable tubular pile 25. The left and right ends of the upper adjustable plate 34 are disposed with equidistant positional adjustment gears 23, which fit with the mounting bracket 41. A convex button hole 54 is disposed at the front side of the adjustable tubular pile 25. As shown in FIGS. 36-37, the pectoral/sternal plate 29 is moveably connected with the upper adjustable plate 34 by bosses 67 that fit with the hinge block 60. A bracket position correction element is disposed between the upper adjustable plate 34 and the pectoral/sternal plate 29. The rear side of the hinge block 60 of the upper adjustable plate 34 is made to be a vertical rectangle surface as the position correction element. The rectangle surface (circle or ellipse) is concave. A strip-shaped gap 37 is disposed from top to bottom of the two ends of the hinge block 60 of the pectoral/sternal plate 29 that corresponds to the hinge block 60. There is a space at the rear side of an adjustable block 71 between the two strip-shaped gaps 37. If the adjustable block 71 is too thick, it is appropriate to open a transversal gap at the upper or lower adjustable block 71 of the upper adjustable plate 34. Because the hinge block 60 is projected backwards, the resilient adjustable block 71 is also projected backwards. The bracket body can be hanged on the upper adjustable plate 34 and is rotable forwards and backwards. As shown in FIGS. 35-38, the lower end of the ventral plate 31 is disposed with another lower crossbeam 40. Another lower crossbeam 40 is behind the adjustable tubular pile 25 and is formed by left and right crossbeams. On the side between another lower crossbeam 40 and the adjustable tubular pile 25 is covered by bosses from top to bottom. The upper end of another lower crossbeam 40 is connected with the lower end of the adjustable column of the adjustable tubular pile 25. Similar to FIG. 42, the left and right frames of the adjustable column and the top three surfaces form the frame edge, the lower surface extends upwards with a turned gear head (pin head). The gear head can be sheathed on the upper or lower equidistant positional adjustment gears of the adjustable tubular pile 25. At the lower side of the positional adjustment gear is connected with the handle 65, extending out of the adjustable groove 13. The adjustable column is moveable up and down. As shown in FIGS. 49-53, the adjustable cover of the mounting bracket comprises a cover plate 82, a median plate 83, a base plate 84, a wheel 72, a moveable plate 98, adjustable cover pin blocks 20, the spring 5 and another handle 65. On the opposite side of the wheel 72 is respectively disposed with a column 73. On the one side of the two adjustable cover pin blocks 20 is respectively disposed with the column 73. The apertures at the two ends of the two moveable plates 98 are moveably connected with wheel 72 and the columns 73 of the two adjustable cover pin blocks 20. The other side of the adjustable cover pin blocks 20 is against the spring 5. The above structure fits with the space formed by the median plate 83 and the cover plate 82. One side of the two adjustable cover pin blocks 20 passes through the median plate 83 and the adjustable groove 13 of the inner side of the baffle 79 with a section. The two adjustable cover pin blocks 20 is extendable along the adjustable groove 13. The median plate 83, the baffle 79 and the base plate 84 form a transversal gap 37, which can be adjusted to fit with the adjustable cover pin blocks 20. The width between the upper adjustable plate 34 and the desk edge can be adjusted via the transversal gap 37. The width fits with the adjustable cover pin block 20 and there is an equidistant positional adjustment gear 23 at the two sides. The base plate 84 can be directly the top or bottom of the desktop 88 (the mounting plate). The shaft 74 on the wheel 72 passes through the aperture of the cover plate 82 to connect with another handle 65.

As an improvement to the bracket body shown in FIG. 44, at the front of the lower end of the adjustable column 49 and at two sides of another button 6 are respectively disposed with 1-2 gear head (s) 18 (pin head 17), which matches with the front wall of the adjustable tubular pile 25 or the positional adjustment gears 23 (positional adjustment holes 22) from top to bottom at the inner side of the adjustable groove 13. The lower end (slightly at the upper position where it is relatively thinner) of the adjustable column 49 is disposed with the bow-shaped leaf spring 51. A bow point 52 of the bow-shaped leaf spring 51 is against the inner side of the rear wall of the adjustable tubular pile 25. As shown in FIGS. 46-47, the adjustable column 49 is the adjustable tube 24. The lower end (slightly at the upper position) of the adjustable tube 24 is disposed with the bow-shaped leaf spring 51. The bow point 52 of the bow-shaped leaf spring 51 is disposed with another button 6, which extends out of the adjustable groove 13 at the front of the adjustable tube 24. The bow points 52 at two sides of another button 6 are respectively disposed with the pin head 17 (gear head). The pin head is sheathed with the positional adjustment holes 22 (positional adjustment gear) from top to bottom at the front wall of the adjustable tubular pile 25. As shown in FIG. 48, inside of the lower end of the adjustable tube 24 is sheathed with an inner sleeve adjustable pin 27. The inner sleeve adjustable pin 27 is between pin slices 56 that are moveably connected at the lower end of the adjustable tube 24 and transversally supports the spring 5. The pin slices 56 have one side (slightly at the lower position) relative to the spring 5 disposed with two buttons 6. The two buttons extend out of the left and right adjustable grooves 13 of the adjustable tubular pile 25. The gear head 18 that is projected from the lower ends (relative sides) of the two pin slices 56 matches with the positional adjustment gear 23 from top to bottom at the inner side of the adjustable groove 13.

As an improvement to the bracket body shown in FIGS. 54-58, inside of the adjustable tubular pile 25 is sheathed with the adjustable column 49, extending from the chest to the thighs (slightly above the thighs). The chin pad 2 is at the place where the upper end (end portion) of the adjustable column 49 extends forwards by 90°. The bottom of the upper end of the adjustable column 49 is disposed with another chin adjustment element. Similar to FIGS. 49-53, the chin adjustment element comprises a cover plate 82, a front plate 76 of the pectoral plate (equivalent to the median plate 83), a rear plate 77 of the pectoral plate (equivalent to the base plate 84), a wheel 72, moveable plates 98, the adjustable cover pin blocks 20, the spring 5 and another handle 65. The front plate 76 and the rear plate 77 form a vertical gap 37 therebetween. The adjustable cover pin blocks 20 at the left and right of the vertical gap 37 match with the adjustable column 49 having the equidistant positional adjustment gears 23. The shaft on the wheel 72 extends out of the aperture of the cover plate 82 and is fixed with another handle 65. The column extending out of the opposite side of the shaft is placed in the aperture at the front of the rear plate 77 via the adjustable groove 13 of the adjustable column 49. The adjustable column 49 is moveable up and down in the vertical gap 37.

As an improvement to the bracket body shown in FIGS. 57-58, in the middle of the front and rear sides of the pectoral/sternal plate 29 that are at the left and right sides of the adjustable tubular pile 25 is disposed with a flat gap extending to the left and right sides. At the upper and lower sides of the flat gap are moveably connected with a moveable pectoral plate 58, respectively. The moveable pectoral plate uses the moveable connecting point as the start point and has the same distance at the left, right and top. Between the moveable pectoral plate 58 and the pectoral/sternal plate 29 is covered by a boss. The moveable pectoral plate 58 is moveable by 90° between flat and stand positions.

As an improvement to the bracket body, as shown in FIGS. 59-62, the inner side of the upper end of the adjustable tubular pile 25 is slightly small and is sheathed with the adjustable column 49 for a vertical cap nut 91. The adjustable column 49 has a small upper section and big lower section and is moveably sheathed with a bolt 33. The lower end of the bolt 33 is connected with the upper end of an arc-shaped boss 67. The lower end of the arc-shaped boss 67 is connected with a knob 93 that can be transversally rotated. As shown in FIGS. 59 and 62, the lower end of the arc-shaped boss 67 can also be connected with umbrella-shaped gears 94. The umbrella-shaped gears 94 are sheathed with the umbrella-shaped gears 94 at the two ends of the knob 93 which is rotatable in the vertical direction. The knob 93 is disposed at the sides or middle of the lower ends of the adjustable tubular piles 25. The knob 93 is moveably connected with the bolt 33 and the adjustable column 49 can rise and descend. As shown in FIGS. 60-61, the arc-shaped boss 67 may be convex or concave or in other shapes as long as the arc-shaped boss 67 and the adjustable tubular piles 25 can rotate.

The mounting bracket 41 can be improved to be the clamp. As shown in FIGS. 63-65, the clamp comprises a mounting bracket follow block 11, a mounting plate 38, a connecting plate 81, fastening bolt 75 and follow block 80. The mounting bracket follow block 11 and the mounting plate 38 are connected by the connecting plate 81. One end of the fastening bolt 75 passes through the mounting plate 38 and is sheathed with the follow block 80. At the opposite sides of the mounting bracket follow block 11 and the follow block 80 can be sheathed with a rubber padding plate. As shown in FIGS. 64-65, the moveable clamp divides the connecting plate 81 into upper and lower sections. The lower section, long and narrow, connects one side of the mounting bracket follow block 11 and is disposed with the adjustable groove 13 from top to bottom. The upper section, short and wide, connects one side of the mounting plate 38 and at the overlapped side with the lower section is disposed with a clamp groove 97 from top to bottom, which fits with the connecting plate 81. A bolt 33 extending out of the lower end of the clamp groove 97 passes through the adjustable groove 13 to engage with a butterfly cap nut 92.

The above frame can be covered with soft a cover pad at the rear of the pectoral/sternal plate 29. The cover pad extends from the rear, left and right sides of the frame cover 3 or the crossbeam 39 or the pectoral/sternal plate 29 to the front side of the pectoral/sternal plate 29. In addition, the cover pad and the pectoral/sternal plate 29 can also be electrified for warm. The bionic and posture-correcting backrest for study provided by the invention can be made of plastics, metal or both.

The foregoing descriptions of the embodiments and their accompanying drawings of the invention are intended to illustrate and not to limit this invention. Various changes and modifications may be made to the embodiments without departing from the spirit of the invention. For example, the upper and lower adjustable plates and the frame can be connected by means of a folding structure as used in the washing machines' covers (little swan). Spring structure or scale structure (for small-bore rifles) or push-pull structure (for cutters) can be used for the chin adjustment element. The mats or its connecting structure used in shopping trolleys (Walmart) can be used for the upper and lower adjustable plates. Furthermore, the existing structures can be left out or exchanged. For example, the chin adjustment element can be left out with only the pectoral/sternal plate. The chin adjustment element, the bracket folding element, the pectoral plate adjustment element and the upper/lower adjustable plates can be exchanged. In summary, people who are skilled in the related art can easily make any changes and modifications, but all changes and modifications made without departing from the invention in its broader aspects are deemed to be within the applied scope of the invention.