CN218978304U

CN218978304U - Simple bookshelf

Info

Publication number: CN218978304U
Application number: CN202222167439.6U
Authority: CN
Inventors: 孙先锋
Original assignee: Suzhou Zhiyixu Electronics Co ltd
Current assignee: Suzhou Zhiyixu Electronics Co ltd
Priority date: 2022-08-17
Filing date: 2022-08-17
Publication date: 2023-05-09
Anticipated expiration: 2032-08-17

Abstract

The utility model relates to the technical field of children's study tables, and discloses a simple bookshelf, which comprises a bookshelf plate, a sliding rail and a supporting piece, wherein one end of the supporting piece is connected with the sliding rail, the other end of the supporting piece is hinged with the bookshelf plate, and an axial locking piece is arranged at the hinged position; the corresponding hinge structure on the back of the bookshelf plate is a turnover connecting seat, and the turnover connecting seat comprises two inner clamping seat plates and a supporting structure, wherein the inner clamping seat plates are provided with inner holes and protruding points; the corresponding hinge structure in the bearing piece is two outer clamping seat plates, and the outer clamping seat plates are provided with outer holes and a circle of groove points; the axial locking piece comprises a connecting shaft and a knob, the connecting shaft is matched in a limiting groove of the outer clamping seat plate for non-rotation after being inserted into the bearing piece and the overturning connecting seat, and the tail of the connecting shaft extends out to be in threaded connection with the knob. Through the mode, the utility model reduces the use of a plurality of parts, so that the whole assembly of the reading frame is simple and easy, the production cost is greatly reduced, and the original functional effect of the reading frame is not influenced.

Description

Simple bookshelf

Technical Field

The utility model relates to the technical field of children learning tables, in particular to a simple bookshelf.

Background

The reading rack is used for placing the unfolded books, and can adjust and limit the angle positions of the books, so that the distance between the books and eyes can be kept for children, myopia is prevented, sitting postures during reading can be adjusted in an assisting mode, and the reading mode of the low-head cat waists is changed.

There is a pull type reading frame in the existing market, which is fixedly installed in the bookshelf of the child study desk, can be hidden in the bookshelf when not in use, is pulled out from the bookshelf to be positioned above the desktop when in use, does not occupy the desktop, and is correspondingly applied for a patent, the patent number of the patent is 201921854273.7, and the patent name of the patent is the pull type child reading frame. The existing reading rack comprises a bookshelf plate for placing books, a sliding rail arranged in the bookshelf and a receiving piece for connecting the bookshelf plate and the sliding rail; the rear end of the bearing piece is fixedly connected with the sliding block in the sliding rail, so that the drawing and pulling functions of the reading frame can be relatively realized; the front end of the bearing piece is hinged with the bookshelf plate, and the overturning angle adjusting function of the reading rack is realized through the axial locking piece.

However, because the axial locking member in the reading frame specifically includes a turnover shaft 42, a compression column 43, a shaft fixing plate 46, two turnover positioning plates 41, and two backing plates 45 (see fig. 6 of the specification of patent 201921854273.7), meanwhile, the hinge plate at the back of the reading frame plate needs to be provided with the positioning column 14, the hinge plate at the end of the receiving member needs to be provided with the positioning pin hole 32, and finally, the complicated assembly of these parts is needed to realize the function effect of angle locking after the reading frame is turned over. Therefore, the reading frame has the problems of more parts and complex assembly, and has high material processing cost and labor assembly cost.

Therefore, it is necessary to design a reading frame which can solve the above technical problems and achieve the technical effect of being hidden in the bookshelf when not in use, and is drawn out from the bookshelf and positioned above the desktop when in use, so that the desk is not occupied.

Disclosure of Invention

The utility model mainly solves the technical problems of more axial locking parts and complex assembly in the existing reading frame while ensuring the original functional effects of the reading frame.

In order to solve the technical problems, the utility model adopts a technical scheme that: provided is a simple bookshelf, comprising: the bookshelf comprises a bookshelf plate for holding books, a sliding rail arranged in the bookshelf and a bearing piece for connecting the bookshelf plate and the sliding rail, wherein one end of the bearing piece is in sliding connection with the sliding rail, the other end of the bearing piece is hinged with the bookshelf plate, and an axial locking piece is arranged at the hinged position; the hinged structure corresponding to the back of the bookshelf plate is a turnover connecting seat, the turnover connecting seat comprises two right opposite inner clamping seat plates and a supporting structure arranged between the two inner clamping seat plates, the supporting structure and the two inner clamping seat plates are of an integrated structure, an inner hole for the axial locking piece to pass through is formed in the inner clamping seat plate, four protruding points distributed around the inner hole are formed in the outer side wall of the inner clamping seat plate, and the four protruding points are respectively located in four right directions up, down, left and right of the inner hole relatively; the corresponding hinge structure in the bearing piece is two opposite outer clamping seat boards, the distance between the inner side walls of the two outer clamping seat boards is equal to the distance between the outer side walls of the two inner clamping seat boards, the outer clamping seat boards are provided with outer holes for the axial locking pieces to pass through, the inner side walls of the outer clamping seat boards are provided with a plurality of groove points distributed around the outer holes and used for being matched with convex points, and the outer wall of one outer clamping seat board is provided with a limiting groove; the axial locking piece comprises a connecting shaft and a knob, the head of the connecting shaft is matched in the limiting groove after the connecting shaft is inserted into the bearing piece and the connecting seat is turned over, the limiting groove is limited to be non-rotatable, and the tail of the connecting shaft extends out to be in threaded connection with the knob; after the rotary knob is locked, the bearing piece and the overturning connecting seat are locked and can not rotate relatively; when the rotary knob is loosened, the bearing piece and the overturning connecting seat are loosened and can rotate relatively.

Preferably, the turnover connecting seat is integrally formed with the bookshelf plate, and the supporting structure comprises five transverse plates and two vertical plates; two ends of the transverse plates are respectively and vertically connected with the two inner clamping seat plates, the five transverse plates are arranged at equal intervals, and the heights of the five transverse plates are low in the middle and gradually increase at two sides; the vertical plates are perpendicular to the five transverse plates, the height of each vertical plate is not higher than the lowest height of each transverse plate, and the two vertical plates are equidistant from the two inner clamping seat plates.

Preferably, the front end of the outer clamping seat plate is provided with a protruding block, the outer side of the inner clamping seat plate is provided with an extension support plate, and when the bookshelf plate is turned 90 degrees from a state parallel to the sliding rail to be vertical to the sliding rail, the protruding block is just propped against the extension support plate; reinforcing ribs are arranged between the extension support plate and the bookshelf plate.

Preferably, the bearing piece is an integrally formed plastic piece, and comprises a sliding connecting part, a turnover connecting part and a middle part for connecting the sliding connecting part and the turnover connecting part; the sliding connection part is two sliding protruding seats corresponding to the two sliding rails respectively, the upper ends of the sliding protruding seats are provided with open sliding grooves, sliding blocks in the sliding rails are fixedly arranged at the bottoms of the open sliding grooves, two sides of the open sliding grooves correspond to two sides of the sliding rails respectively, two limiting strips are arranged on the inner side walls of the open sliding grooves and can correspondingly abut against the outer side walls of the sliding rails; the bottom of the sliding protruding seat is also hollow with a rectangular groove; the turnover connecting parts are two outer clamping seat boards, a U-shaped connecting structure is formed between the outer clamping seat boards and the middle part, round angle natural transition is formed between the inner side wall of the outer clamping seat boards and the end face of the middle part, the outer side walls of the outer clamping seat boards are relatively expanded to the middle part, but the outer side walls of the outer clamping seat boards are still parallel to the outer side walls of the middle part, and arc natural transition is formed between the outer side walls of the outer clamping seat boards and the outer side walls of the middle part.

Preferably, the head of the connecting shaft is in a regular hexagon shape, the limiting groove is a regular hexagonal groove, and the center of the regular hexagonal groove coincides with the center of the outer hole.

Preferably, the outer clamping seat plate provided with the regular hexagonal groove is also provided with a rectangular through groove communicated with the regular hexagonal groove.

Preferably, the knob comprises a rotary main body part and a rotary auxiliary body part, the rotary main body part rotates and is of an integral structure with the rotary auxiliary body part, the outer diameter of the rotary main body part is larger than that of the rotary auxiliary body part, an inner thread is arranged on the inner side wall of the rotary auxiliary body part, and the rotary auxiliary body part is in threaded connection with the tail part of the connecting shaft.

Preferably, the knob comprises a rotary main body part, a telescopic adjusting part and a rotary auxiliary body part, wherein the telescopic adjusting part is of a telescopic sleeve type structure, a minimum sleeve of the telescopic adjusting part is fixedly connected with the rotary auxiliary body part, and a maximum sleeve of the telescopic adjusting part is fixedly connected with the rotary main body part; after the telescopic adjusting part stretches into place, the rotary main body part completely stretches out of the bookshelf plate; after the telescopic adjusting part is shortened, the rotary main body part is hidden at the back of the bookshelf plate.

Preferably, the largest sleeve of the telescopic adjusting part is fixedly embedded in the rotating main body part, and the telescopic adjusting part can be hidden in the rotating main body part after the telescopic adjusting part is shortened to be in place.

Preferably, the outer surface of the rotating main body part is also provided with anti-skid patterns.

The beneficial effects of the utility model are as follows:

(1) According to the utility model, the requirement on the axial locking piece is reduced by changing the connecting structure of the bearing piece and the turnover connecting seat, so that the use of a plurality of parts is reduced, the whole assembly of the reading frame is simple and easy, the production cost is greatly reduced, and the original functional effect of the reading frame is not influenced.

(2) The whole and bookshelf board of upset connecting seat are integrative, and the bearing structure's in the upset connecting seat design not only makes its structure simple, processing production convenient, has still guaranteed the structural strength of upset connecting seat self moreover, has further improved the bearing capacity of reading frame again.

(3) The design of the protruding block and the extension support plate prevents the bookshelf plate from being overturned excessively to an invalid use state. The reinforcing ribs not only improve the supportable strength of the extension support plate, but also improve the integral structural strength of the overturning connecting seat.

(4) The integrally formed plastic piece design of the bearing piece changes the processing difficulty of the original bearing piece made of iron sheets and reduces the material cost. Through the design to self structure, like the design of expanding outward of U word form connection structure, outer card bedplate etc. has guaranteed the required structural strength of receiver.

(5) The connecting shaft can be a common hexagon head screw on the market, the universality is high, and the corresponding regular hexagon grooves can directly limit the rotation of the connecting shaft, so that the operation on the axial locking piece is convenient.

(6) The design of the telescopic adjusting part in the knob can make the operation of the axial locking piece easier. When the overturning angle of the bookshelf plate needs to be adjusted, the knob is extended by extending a hand to the back of the bookshelf plate until the rotating main body part of the knob extends out of the bookshelf plate completely, and then the knob can be rotated to control whether the bookshelf plate can be overturned or not. In the whole process of controlling the knob to rotate (the knob is loosened, the bookshelf plate is pulled to a proper angle and the knob is locked), the whole process time is long, particularly, the bookshelf plate is in a proper angle, a user possibly needs to try for a plurality of times, and hands do not need to extend to the back of the bookshelf plate, so that the convenience of adjustment is greatly improved. When not in use, the knob is pushed back, and can be hidden at the back of the bookshelf plate, so that the simplicity is high, and the aesthetic feeling is not influenced. The outer surface of the rotary main body part is provided with anti-skid patterns, so that the rotary knob can be rotated conveniently.

Drawings

FIG. 1 is a schematic perspective view of a simple bookshelf according to the present utility model;

FIG. 2 is a schematic perspective view of a simple bookshelf according to the present utility model at another angle;

FIG. 3 is a schematic view of a partial structure of a simple bookshelf of the present utility model;

FIG. 4 is a schematic diagram of a structure of a turnover connecting seat in a simple bookshelf of the utility model;

FIG. 5 is a schematic view of the structure of the turnover connecting seat in the simple bookshelf at another angle;

FIG. 6 is a schematic view of the structure of the receiving member in the simple bookshelf of the utility model;

fig. 7 is a schematic view of the structure of the receiving member of the simple bookshelf in another angle.

The components in the drawings are marked as follows: 1. a bookshelf plate; 2. turning over the connecting seat; 21. an inner card seat plate; 211. an inner bore; 212. a bump; 22. a support structure; 221. a cross plate; 222. a riser; 23. a support plate; 3. a slide rail; 4. a receiving member; 41. an outer card seat plate; 411. an outer aperture; 412. groove points; 413. a regular hexagonal groove; 414. rectangular through grooves; 415. a protruding block; 42. a sliding boss; 421. an open runner; 422. a restriction strip; 423. rectangular grooves; 5. an axial locking member; 51. a connecting shaft; 511. a head; 52. a knob; 521. a rotating body part; 522. the slave body is rotated.

Detailed Description

The preferred embodiments of the present utility model will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present utility model.

Referring to fig. 1 to 7, an embodiment of the present utility model includes:

example 1

A simple bookstand, comprising: the bookshelf plate 1, the upset connecting seat 2, the slide rail 3, receiver 4 and axial retaining member 5.

The front surface of the bookshelf plate 1 can be used for placing books, and the turnover connecting seat 2 is integrally formed on the back surface of the bookshelf plate 1. The flip-over connecting seat 2 comprises two diametrically opposite inner card seat plates 21 and a supporting structure 22 arranged between the two inner card seat plates 21, wherein the supporting structure 22 can ensure that the two inner card seat plates 21 are not deformed inwards under the action of opposite external forces. The inner clamping seat plate 21 is provided with an inner hole 211 for the axial locking piece 5 to pass through, the outer side wall of the inner clamping seat plate 21 is provided with four protruding points 212 distributed around the inner hole 211, and the four protruding points 212 are respectively positioned in four positive directions of up, down, left and right of the inner hole 211.

Specifically, the support structure 22 includes five cross plates 221 and two risers 222; two ends of the transverse plates 221 are respectively and vertically connected with the two inner clamping seat plates 21, the five transverse plates 221 are arranged at equal intervals, and the heights of the five transverse plates 221 are in a trend of low middle and gradually increased at two sides; the vertical plates 222 vertically intersect with the five transverse plates 221, the height of the vertical plates 222 is not higher than the lowest height of the transverse plates 221, and the two vertical plates 222 are equidistant from the two inner clamping seat plates 21. The structure is simple in layout and reasonable in design, and can achieve a strong supporting effect.

The sliding rail 3 is fixedly arranged in a bookcase on the children study desk, and the sliding rail 3 is provided with a pair. One end of the bearing piece 4 is slidably connected with the sliding rail 3, and in particular, the bearing piece 4 is fixedly connected with a sliding block in the sliding rail 3; the other end of the receiving member 4 is provided with a pair of opposite outer clamping seat plates 41, the distance between the inner side walls of the two outer clamping seat plates 41 is equal to the distance between the outer side walls of the two inner clamping seat plates 21, and the two outer clamping seat plates 41 can be correspondingly clamped on the outer sides of the two inner clamping seat plates 21 to form a clamping state without clamping force. An outer hole 411 for the axial locking member 5 to pass through is formed in the outer card seat plate 41, a plurality of groove points 412 distributed around the outer hole 411 are formed in the inner side wall of the outer card seat plate 41, and when the outer hole 411 and the inner hole 211 are coaxial, the groove points 412 are matched with the protruding points 212; through the cooperation of the convex points 212 and different groove points 412, the turnover adjustment of the bookshelf plate 1 can be better realized, and the axial locking piece 5 is convenient for locking the preliminary locking of the turnover position of the front bookshelf plate 1. A regular hexagonal groove 413 is formed in the outer wall of one outer clamping seat plate 41, and the center of the regular hexagonal groove 413 is overlapped with the center of the outer hole 411; the regular hexagonal groove 413 may be used to rotationally limit one end of the axial lock 5. The outer card seat board 41 provided with the regular hexagonal groove 413 can be also provided with a rectangular through groove 414 communicated with the regular hexagonal groove 413, so that the later installation and maintenance can be facilitated.

Specifically, the receiving member 4 is an integrally formed plastic member, and the receiving member 4 includes a sliding connection portion, a turnover connection portion, and an intermediate portion connecting the sliding connection portion and the turnover connection portion. The sliding connection part is provided with two sliding convex seats 42, and the relative positions of the two sliding convex seats 42 respectively correspond to the two sliding rails 3; the upper end of the sliding protruding seat 42 is provided with an open sliding groove 421, the sliding block is fixedly arranged at the bottom of the open sliding groove 421, two sides of the open sliding groove 421 respectively correspond to two sides of the sliding rail 3, two limiting strips 422 are further arranged on the inner side wall of the open sliding groove 421, the limiting strips 422 are propped against the outer side wall of the sliding rail 3, stability in the sliding process can be improved, shaking is avoided, and the sliding device is convenient to install. The bottom of the sliding boss 42 is also hollow with a rectangular groove 423, which reduces the material cost, reduces the weight of the reading rack itself, and does not affect the structural strength. The overturning connecting parts are two outer clamping seat boards 41, a U-shaped connecting structure is formed between the outer clamping seat boards 41 and the middle part, round angle natural transition is formed between the inner side walls of the outer clamping seat boards 41 and the end face of the middle part, the outer side walls of the two outer clamping seat boards 41 are correspondingly expanded outside the middle part, but the outer side walls of the outer clamping seat boards 41 are still parallel to the outer side walls of the middle part, and arc natural transition is formed between the outer side walls of the outer clamping seat boards 41 and the outer side walls of the middle part; the structural design ensures that the connection strength of the overturning connecting part and the middle part is higher, and the integral structural strength of the bearing piece 4 is good.

The axial locking member 5 comprises a connecting shaft 51 and a knob 52. One end of the connecting shaft 51 is a head 511, the head 511 is in a regular hexagon shape, the cross section of the head 511 is larger than that of other parts, the other end of the connecting shaft 51 is a tail, and an external thread is arranged on the outer side wall of the tail. The knob 52 includes a rotating main body 521 and a rotating slave body 522, the rotating main body 521 rotates together with the rotating slave body 522, the outer diameter of the rotating main body 521 is larger than the outer diameter of the rotating slave body 522, an internal thread is provided on the inner side wall of the rotating slave body 522, and the rotating slave body 522 can be connected with the tail of the connecting shaft 51 by a thread. Specifically, a nut matched with the tail of the connecting shaft 51 may be fixedly embedded in the rotating slave body 522 of the knob 52, or an adaptive threaded hole may be directly formed in the rotating slave body 522 of the knob 52. The outer surface of the rotating body 521 is also provided with anti-slip patterns to facilitate better rotation of the knob 52. When mounted, the tail of the connecting shaft 51 is inserted from the outer clamping seat board 41 with the regular hexagonal groove 413, passes through the two inner clamping seat boards 21 and finally passes out from the other outer clamping seat board 41, and then can be connected with the knob 52 in a threaded manner.

After the connecting shaft 51 is inserted into the bearing piece 4 and the turnover connecting seat 2, the head 511 is matched in the regular hexagonal groove 413, and the tail extends out to be in threaded connection with the rotation of the knob 52 from the body 522. When the knob 52 is rotated and locked (the head 511 of the connecting shaft 51 abuts against the bottom of the regular hexagonal groove 413, and the rotation of the knob 52 abuts against the outer side wall of the outer socket plate 41 from the body 522), the socket 4 and the flip-over connecting seat 2 are locked and can not rotate relatively. When the knob 52 is rotated and loosened, the supporting piece 4 and the turnover connecting seat 2 can be loosened and rotated relatively, so that turnover adjustment of the bookshelf plate 1 can be performed. The locking principle here is to limit whether the two outer card base plates 41 can be spread out relative to the two inner card base plates 21 by controlling the distance between the rotating slave body 522 and the head 511 (the relative position of the knob 52 on the connecting shaft 51), so as to realize whether the flip connecting base 2 can rotate relative to the socket 4.

The front end of the outer clamping seat board 41 is provided with a protruding block 415, the outer side of the inner clamping seat board 21 is provided with an extension support board 23, and when the bookshelf board 1 is turned 90 degrees from a state parallel to the sliding rail 3 to a state perpendicular to the sliding rail 3 (the turnover connecting seat 2 is turned 90 degrees relative to the bearing piece 4), the protruding block 415 just abuts against the extension support board 23, and excessive turnover of the bookshelf board 1 can be limited. Reinforcing ribs are further arranged between the extension support plates 23 and the bookshelf plates 1, and the extension support plates 23 can be flush with the outermost transverse plates 221, so that the overall structural strength of the turnover connecting seat 2 is improved again.

Example 2

A simple bookstand differs from embodiment 1 only in that the knob 52 portion is upgraded and improved.

The knob 52 includes a rotating main body 521, a telescopic adjusting portion and a rotating slave body 522, the telescopic adjusting portion is of a telescopic sleeve type structure, a minimum sleeve of the telescopic adjusting portion is fixedly connected with the rotating slave body 522, and a maximum sleeve of the telescopic adjusting portion is fixedly connected with the rotating main body 521. Specifically, the inner diameter of the smallest sleeve in the telescopic adjusting part is not smaller than the inner diameter of the rotating slave body 522, so as to accommodate the tail of the connecting shaft 51 after locking, and the largest sleeve in the telescopic adjusting part is fixedly embedded in the rotating main body 521; the telescopic adjusting part comprises six sleeves which are sequentially matched and connected, and the connection between every two of the six sleeves is identical to the telescopic structure of the umbrella handle of the existing folding umbrella.

After the telescopic adjusting part is extended in place, the rotary main body 521 completely extends out of the bookshelf plate 1, so that the bookshelf plate can be conveniently rotated to the rotary main body 521, hands do not need to extend to the back of the bookshelf plate 1, and the adjusting convenience is greatly improved; after the telescopic adjusting part is shortened, the rotary main body 521 is hidden at the back of the bookshelf plate 1; after the expansion and contraction adjusting portion is shortened in place, the expansion and contraction adjusting portion may be hidden in the rotating body portion 521.

The foregoing description is only illustrative of the present utility model and is not intended to limit the scope of the utility model, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present utility model.

Claims

1. A simple bookstand, comprising: the bookshelf comprises a bookshelf plate for holding books, a sliding rail arranged in the bookshelf and a bearing piece for connecting the bookshelf plate and the sliding rail, wherein one end of the bearing piece is in sliding connection with the sliding rail, the other end of the bearing piece is hinged with the bookshelf plate, and an axial locking piece is arranged at the hinged position; it is characterized in that the method comprises the steps of,

the hinged structure corresponding to the back of the bookshelf plate is a turnover connecting seat, the turnover connecting seat comprises two right opposite inner clamping seat plates and a supporting structure arranged between the two inner clamping seat plates, the supporting structure and the two inner clamping seat plates are of an integrated structure, an inner hole for the axial locking piece to pass through is formed in the inner clamping seat plate, four protruding points distributed around the inner hole are formed in the outer side wall of the inner clamping seat plate, and the four protruding points are respectively located in four right directions up, down, left and right of the inner hole relatively;

the corresponding hinge structure in the bearing piece is two opposite outer clamping seat boards, the distance between the inner side walls of the two outer clamping seat boards is equal to the distance between the outer side walls of the two inner clamping seat boards, the outer clamping seat boards are provided with outer holes for the axial locking pieces to pass through, the inner side walls of the outer clamping seat boards are provided with a plurality of groove points distributed around the outer holes and used for being matched with convex points, and the outer wall of one outer clamping seat board is provided with a limiting groove;

the axial locking piece comprises a connecting shaft and a knob, the head of the connecting shaft is matched in the limiting groove after the connecting shaft is inserted into the bearing piece and the connecting seat is turned over, the limiting groove is limited to be non-rotatable, and the tail of the connecting shaft extends out to be in threaded connection with the knob; after the rotary knob is locked, the bearing piece and the overturning connecting seat are locked and can not rotate relatively; when the rotary knob is loosened, the bearing piece and the overturning connecting seat are loosened and can rotate relatively.

2. A simple bookstand according to claim 1, wherein: the turnover connecting seat is integrally formed with the bookshelf plate, and the supporting structure comprises five transverse plates and two vertical plates; two ends of the transverse plates are respectively and vertically connected with the two inner clamping seat plates, the five transverse plates are arranged at equal intervals, and the heights of the five transverse plates are low in the middle and gradually increase at two sides; the vertical plates are perpendicular to the five transverse plates, the height of each vertical plate is not higher than the lowest height of each transverse plate, and the two vertical plates are equidistant from the two inner clamping seat plates.

3. A simple bookstand according to claim 2, wherein: the front end of the outer clamping seat plate is provided with a protruding block, the outer side of the inner clamping seat plate is provided with an extension support plate, and when the bookshelf plate is turned 90 degrees from a state parallel to the sliding rail to be vertical to the sliding rail, the protruding block is just propped against the extension support plate; reinforcing ribs are arranged between the extension support plate and the bookshelf plate.

4. A simple bookstand according to claim 1, wherein: the bearing piece is an integrally formed plastic piece and comprises a sliding connecting part, a turnover connecting part and a middle part for connecting the sliding connecting part and the turnover connecting part; the sliding connection part is two sliding protruding seats corresponding to the two sliding rails respectively, the upper ends of the sliding protruding seats are provided with open sliding grooves, sliding blocks in the sliding rails are fixedly arranged at the bottoms of the open sliding grooves, two sides of the open sliding grooves correspond to two sides of the sliding rails respectively, two limiting strips are arranged on the inner side walls of the open sliding grooves and can correspondingly abut against the outer side walls of the sliding rails; the bottom of the sliding protruding seat is also hollow with a rectangular groove; the turnover connecting parts are two outer clamping seat boards, a U-shaped connecting structure is formed between the outer clamping seat boards and the middle part, round angle natural transition is formed between the inner side wall of the outer clamping seat boards and the end face of the middle part, the outer side walls of the outer clamping seat boards are relatively expanded to the middle part, but the outer side walls of the outer clamping seat boards are still parallel to the outer side walls of the middle part, and arc natural transition is formed between the outer side walls of the outer clamping seat boards and the outer side walls of the middle part.

5. A simple bookstand according to claim 1, wherein: the head of the connecting shaft is in a regular hexagon shape, the limiting groove is a regular hexagonal groove, and the center of the regular hexagonal groove coincides with the center of the outer hole.

6. A simple bookstand according to claim 5, wherein: the outer clamping seat plate provided with the regular hexagonal groove is also provided with a rectangular through groove communicated with the regular hexagonal groove.

7. A simple bookstand according to claim 1, wherein: the knob comprises a rotary main body part and a rotary auxiliary body part, wherein the rotary main body part rotates and is of an integral structure with the rotary auxiliary body part, the outer diameter of the rotary main body part is larger than that of the rotary auxiliary body part, internal threads are arranged on the inner side wall of the rotary auxiliary body part, and the rotary auxiliary body part is in threaded connection with the tail part of the connecting shaft.

8. A simple bookstand according to claim 1, wherein: the knob comprises a rotary main body part, a telescopic adjusting part and a rotary auxiliary body part, wherein the telescopic adjusting part is of a telescopic sleeve type structure, a minimum sleeve of the telescopic adjusting part is fixedly connected with the rotary auxiliary body part, and a maximum sleeve of the telescopic adjusting part is fixedly connected with the rotary main body part; after the telescopic adjusting part stretches into place, the rotary main body part completely stretches out of the bookshelf plate; after the telescopic adjusting part is shortened, the rotary main body part is hidden at the back of the bookshelf plate.

9. A simple bookstand according to claim 8, wherein: the largest sleeve in the telescopic adjusting part is fixedly embedded in the rotating main body part, and after the telescopic adjusting part is shortened in place, the telescopic adjusting part can be hidden in the rotating main body part.

10. A simple bookstand according to claim 7, 8 or 9, wherein: the outer surface of the rotating main body part is also provided with anti-skid patterns.