KR200381979Y1 - Variable device of board for desk - Google Patents

Abstract

The present invention relates to a top plate variable device of a learning desk that allows the user to freely adjust the position of the top desk and the front and rear direction of the desk.

The upper plate variable apparatus of the lecture desk according to the present invention is coupled to both sides of the lower side of the upper plate and a housing having a rotating shaft penetrating horizontally therein, and an operating lever fixed to the rotating shaft end to the outside of the housing to rotate the rotating shaft; A first engagement member fitted to the rotation shaft to be in close contact with one side of the housing and fixed to the upper end of the support frame; and a first engagement member fitted to the rotation shaft to be in close contact with the other side of the housing and rotated together with the housing and sliding reciprocating along a rotation axis for a certain period. And a second engagement member that is engaged with the member at various angles, and coupling means installed between the first and second engagement members to selectively engage or space the engagement members in accordance with the rotational direction of the operating lever.

Description

Variable device of board for desk {Variable device of board for desk}

The present invention relates to a top plate variable device of a learning desk that allows the user to freely adjust the position of the top desk and the front and rear direction of the desk.

As shown in Figure 1, the conventional desk for writing is a top plate (1) made of a predetermined shape so that you can write on a book, and a support frame for supporting the top plate (1) at a constant height from the floor It consists of (2). The top plate 1 and the support frame 2 are fixed with bolts 3 and nuts 4.

However, because the conventional desk for the structure of the above structure is made uniform without considering the physical characteristics of the individual users, there were many inconveniences in use.

In particular, since the top plate 1 is fixed to the support frame 2 and the user cannot adjust the distance between the top plate 1 and the user or the inclination angle of the top plate 1, the desk is placed in the correct posture suitable for the user. There is a problem that cannot be used.

If you study for a long time in the above state, fatigue progresses rapidly, learning efficiency is lowered, and an unstable posture is solidified, resulting in very harmful health.

The present invention has been made in consideration of the above-described conventional problems, and the object of the present invention is to provide a variable desk top variable apparatus for varying the top of the desk according to the user's request so that the user can work on the correct posture suitable for them. have.

In order to achieve the above object, the present invention is a variable device of the desk desk having a top plate made of a predetermined shape so as to place a book or writing, and a support frame for supporting the top plate at a constant height from the bottom, A housing coupled to both lower sides of the upper plate and having a rotating shaft horizontally penetrating therein; an operation lever fixed to the rotary shaft end to the outside of the housing to rotate the rotating shaft; and fitted to the rotating shaft to be in close contact with one side of the housing. A first engagement member fixed to an upper end of the frame, a second engagement member fitted to the rotation shaft to be in close contact with the other side of the housing, rotated together with the housing, and engaged with the first engagement member at a plurality of angles while sliding reciprocating for a predetermined time along the rotation shaft; Is installed between the first and second engagement member, the teeth selectively depending on the rotational direction of the operating lever It characterized in that it comprises a coupling means for engaging or spaced apart the engaging member.

In addition, the coupling means is recessed on the housing facing surface of the second engagement member is rotated with the rotating shaft and is raised at one point of the second engagement member by moving the second engagement member toward the first engagement member side by the ridges. It is composed of a flexible flange to be made and the elastic member is provided between the engaging members to provide a resilient force so that the engaged members are spaced apart.

In addition, an insertion protrusion inserted into the housing surface is formed on the housing facing surface of the second engagement member, and a groove into which the insertion protrusion is inserted is formed on the inner surface of the housing. The groove is preferably extended to the bottom of the housing so that the second engagement member can be entered into the housing through the insertion projection.

In addition, a protrusion having a predetermined height is formed on a bottom of a top of the bent portion of the bent flange, and a center of the housing facing surface of the second engagement member is formed at the bottom of the indented surface along the rotational path of the bent flange recessed surface and the protrusion of the bent flange. The formed projection receiving groove and a projection formed at a predetermined height from the bottom of the accommodation groove are formed, and the projection of the bending flange is located above the projection of the accommodation groove when the projection of the bending flange passes through the projection formed in the accommodation groove. To be raised from the housing contact surface of the second engagement member.

In addition, in the second engagement member grooves toward the center of the engagement member along the outer circumferential surface is formed at a predetermined interval, and one side of the housing facing the groove is inserted into the groove portion is part of the coupling member is not in the engagement state An elastic support member may be fixed to prevent the housing from rotating by its own weight.

In addition, a support portion protruding along the movement path of the lower end of the housing may be further formed on the outside of the first engagement member to support the housing when an impact from an upper portion thereof occurs.

In addition, a hub may be further installed between the housing and the first engagement member so as to be in close contact with the rotating shaft while limiting the rotating section of the rotating shaft.

According to the present invention, the housing may be fixedly coupled to the top plate through a guide rail which is fixed to the bottom of the top plate in the front-rear direction and fitted to the top outside of the housing.

In this case, the housing has an incision formed by a pair of vertical incision line formed from the upper end of the housing on one side, the hub further comprises a vertical flange extending from the outer peripheral surface to be in close contact with the incision, Preferably, the cutout is formed to gradually increase in thickness along the rotational direction of the hub such that the housing is pushed by the vertical flange and protrudes out of the housing so as to be pressed and fixed to the inside of the guide rail.

In addition, a locking groove is formed at a predetermined interval inside the guide rail so that the guide rail and the housing are slidably coupled in multiple stages, and an elastic support member is fixed to the upper end of the housing by inserting a part of the body into the locking groove. Can be.

The features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments based on the accompanying drawings. Prior to this, terms or words used in the present specification and claims are defined in the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her own design. It must be interpreted to mean meanings and concepts.

As shown in Figures 2 and 3, the upper plate variable device 100 of the lecture desk according to the present invention is a top plate (1) and the upper plate (1) made of a predetermined shape so that books can be placed or writing It is applied to a desk having a support frame 2 which supports at a constant height from the floor.

The upper plate variable apparatus 100 of the desk of the present invention is coupled to both lower sides of the upper plate 1, the housing 110 is provided with a rotating shaft 120 penetrating horizontally therein, and the rotating shaft to the outside of the housing 110 An operating lever 130 fixed to the end to rotate the rotary shaft 120 and the first fixed to the upper end to the support frame 2 is fitted to the rotary shaft 120 in close contact with one side 111 of the housing 110 The second fitting member 140 and the second shaft is fitted to the rotary shaft 120 to be rotated together with the housing 110 and meshed with the first coupling member 140 at various angles while sliding reciprocating for a certain period along the rotary shaft 120. The coupling member 150 is installed between the first and second engagement members 140 and 150 and is configured to engage or space the engagement members 140 and 150 selectively according to the rotational direction of the operation lever 130. do.

The coupling means is recessed in the housing 110 facing surface 112 of the second engagement member 150, rotates together with the rotation shaft 120 and is raised at one side of the second engagement member 150 by the second Bending flange 160 to move the coupling member 150 toward the first coupling member 140 and the coupling is made, and the coupling members (140,150) installed between the coupling members (140,150) to be spaced apart It is composed of an elastic member 170 that provides a reaction force.

Both sides of the housing 110 are formed with a through hole 110a penetrating the housing horizontally. Through the through-hole (110a) The rotating shaft 120 is fitted. In addition, the rotation shaft 120 is rotatably installed in the housing 110 by the operation lever 130 and the reinforcing cap 175 coupled by bolts at both ends.

The operation lever 130 is bolted to the end of the rotating shaft 120 on the outer surface of the housing 110 to rotate the rotating shaft 120.

Inside the housing 110, the first engagement member 140 and the second engagement member 150 are fitted to face each other on the rotation shaft 120. The fitting members 140 and 150 are fitted to the rotating shaft 120 through respective through holes 140a and 150a formed in the center thereof, and are installed to be in close contact with the inner surfaces 111 and 112 of the housing 110, respectively. 150a is freely rotated in a state where the fitting members 140 and 150 are fitted to the rotary shaft 120 and are formed larger than the outer diameter of the rotary shaft 120 to allow the sliding members 140 and 150 to slide along the rotary shaft 120.

In addition, a groove 113 is formed on the second engagement member contact surface 112 of the housing 110 to be coupled to the second engagement member 150. And the second engaging member 150 is formed with an insertion protrusion 151 fitted into the groove 113. The groove 113 is slidingly coupled from the lower side of the housing 110 to the housing 110 through the insertion protrusion 151 in a state in which the second engagement member 150 is engaged with the first engagement member 140. It is preferable to vertically pass through the through-hole (110a) of the housing 110 to the open lower end of the housing (110).

As shown in FIGS. 4 to 8, each of the first engagement member 140 and the second engagement member 150 faces each other, and the engagement protrusions 145 and 155 that face the outer circumferential direction from the center of each surface are fixed at an angle. Is uniformly formed. The engagement protrusions 145 and 155 allow the first engagement member 140 and the second engagement member 150 to be engaged with each other at multiple angles and to maintain a stable engagement state.

The first engagement member 140 is fixed to the upper end of the support frame 2 through the fitting portion 141 formed at the lower end, the fitting portion 141 is wrapped on both sides of the support frame 2 to the outside in a state It is firmly fixed to the support frame (2) by a screw fastened by.

The second engagement member 150 has a curved flange recessed surface 152 formed at the center of the contact surface with the housing 110, and moves along the edge of the curved flange 160 toward the bottom of the recessed surface 152. It is provided with an annular receiving groove 153 formed.

On the other hand, when the outer peripheral surface of the second engagement member 150 is not in the engaged state, the second engagement member 150 along the outer circumferential surface of the second engagement member 150 so that the housing 110 is not rotated by its own weight The grooves 156 facing the center are formed at regular intervals, and the elastic support member 190 into which the body part is inserted is fixed to the first engagement member 140 facing the grooves 156. It is desirable to be.

In addition, according to the present invention, the housing 110 on the outer surface of the first engagement member 140 in order to prevent the housing 110 from being damaged due to the impact applied to the housing 110 when the impact from the top. A support 146 protruding along the movement trajectory of the lower end may be provided.

In addition, the support protrusion 116 may be further provided to protrude to the outside of the housing 110 to be supported by the reinforcing cap 175 when an impact occurs from the top.

The bent flange 160 has an edge surface 160c seated on the depression surface 152 and a curved edge surface 160c formed to repeat the depression and ridge based on the depression surface 152 according to the rotation section. And a connecting piece 160d for interconnecting the center surface 160b and the edge surface 160c.

The through hole 160a fitted to the rotation shaft 120 is formed at the central surface 160b of the through hole. The through hole 160a is formed such that the flexure flange 160 is slidably moved while allowing the sliding flange 160 to slide along the rotation shaft 120. To this end, in the present embodiment, the cross section of the rotating shaft 120 installed in the housing 110 is a square, and the cross section of the through hole 160a of the bending flange 160 and the rotating shaft 120 installed in the housing 110. The cross section of the same was formed and formed differently from the through-holes (140a, 150a) of the engagement member (140,150).

The edge surface 160c has a bend section that is gradually raised from the bottom to the center surface 160b to the bottom and passes down to the bottom after passing through the top formed at an arbitrary point. In the present embodiment, the bent flange 160 formed in the lowermost part and the highest part are illustrated.

On the other hand, protrusions 161 and 154 having predetermined heights are formed on the bottom of the top of the bent flange 160 and the bottom of the receiving groove 153 of the second engagement member 150, respectively. The height of the protrusion 154 formed in the receiving groove 153 of the second engagement member 150 protrudes from the edge of the second engagement member 150 when the lowest portion of the bending flange 160 passes through the protrusion 154. Is formed so as not to, the projection 161 formed on the bottom of the top of the bending flange 160 is the rotating shaft in the state in which the bending flange 160 is in contact with the inner surface of the housing 110 in the recessed groove 153 Rotate along the 120 is formed to a height that can be naturally positioned to the top of the protrusion 154 formed in the receiving groove 153.

Therefore, both sides of the protrusion 154 or the protrusion 161 of the bending flange 160 formed in the receiving groove 153 is preferably cut to allow the two members 150 and 160 to pass naturally.

In addition, an elastic member 170 is provided between the coupling members 140 and 150 to provide a repulsive force so that the coupling members 140 and 150 in the engaged state are spaced apart from each other.

As shown in FIG. 9, the hub 180 may be further provided between the housing 110 and the first engagement member 140 to limit the rotation section of the rotation shaft 120. The hub 180 is a plate-shaped member and a through hole 180a into which the rotating shaft 120 is fitted is formed at the center thereof. The through hole 180a has the same cross section as that of the rotating shaft 120 similar to the through hole 160a of the bent flange 160 such that the hub 180 rotates together with the rotating shaft 120.

In addition, a vertical flange 181 is formed outside the hub 180. The vertical flange 181 is formed along the outer circumferential surface of the hub 180, a predetermined section is formed when both sides are interfered with the inner surface of the housing 110 during rotation with the rotating shaft 120 to rotate the rotation shaft 120 in a predetermined section Restrict.

In addition, the hub 180 has a horizontal flange 182 for supporting the inner surface 112 of the housing 110 opposite from the outer peripheral surface.

According to the present invention, as shown in FIG. 10, the housing 110 is fixed to the lower portion of the upper plate 1 in the front-rear direction through the guide rail 200 fitted into the upper outer side of the housing 110. It may be supported by sliding coupling with (1).

In this case, the housing 110 is further provided with an incision 116 formed by a pair of vertical incision line 115 formed from the top of the housing 110 on one side, the incision 116 is When the fitting is pushed by the vertical flange 181 to protrude to the outside of the housing 110, the thickness gradually increases along the rotational direction of the hub 180 so that the housing 110 is pressed and fixed to the inside of the guide rail 200. It is preferable to form it enlarged.

In addition, the coupling end surface of the guide rail 200 and the housing 110 may be formed asymmetrically so as not to reverse the coupling direction of the upper plate (1) to be slidingly coupled (see Fig. 3).

In addition, the guide rail 200 and the housing 110 is further provided with engaging grooves 210 formed at a predetermined interval inside the guide rail 200 so as to slide in multiple stages, the upper end of the housing 110 A portion of the body may be inserted into the locking groove 210 so that the elastic support member 190 may be fixed.

The upper plate variable device of the lecture desk of the present invention having such a configuration is assembled in the following manner.

First, the hub 180, the first engagement member 140, the elastic member 170, the second engagement member 150, and the bending flange 160 are preassembled in order. The temporary assembly is slidably moved inwardly of the housing 110 along the groove 113 of the housing 110 through the protrusion 161 of the second engagement member 150, and in this state, the rotating shaft 120 is assembled into the temporary assembly. The through holes of the sieve are continuously assembled to the housing 110.

When the rotating shaft 120 is assembled to the housing 110, the variable lever according to the present invention by bolting the operating lever 130 to the rotating shaft end is installed to the hub 180 and bolted to the reinforcement cap 175 to the opposite rotating shaft end Assembly of the 100 is completed.

The upper plate variable device 100 of the present invention assembled as described above is fixed to the support frame 2 by screwing through the lower end of the first engaging member 140 protruding to the lower portion of the housing 110, the housing It is fitted to the guide rail 200 fixed to the upper end of 110 to be combined with the upper plate 1 is installed and used on the desk for lectures.

11A and 11B are diagrams showing the internal state of the housing before and after the engagement of the engagement members constituting the present invention, respectively, and will explain the operation of the desk top plate variable apparatus according to the present invention.

The housing 110 in the initial state in which the engagement members 140 and 150 are not engaged is freely rotatable with the second engagement member 150 about the rotation shaft 120. Set the angle of the upper plate (1) and the distance between yourself and the upper plate (1) to suit.

Since the housing 110 and the upper plate 1 are connected through the guide rails 200, the user slides the upper plate 1 by a simple operation of pulling or pushing the upper plate 1 by hand without applying great force. The proper distance can be set.

At this time, the engaging groove 210 of a predetermined interval is formed on the inside of the guide rail 200 and a portion of the body is inserted into the engaging groove 210 in the upper end of the housing 110 is the elastic member 170 is caught When fixed, the user can adjust the distance to the top plate 1 in multiple stages.

In addition, when the coupling end surface of the guide rail 200 and the housing 110 is formed asymmetrically, there is no confusion in assembling when the coupling direction of the upper plate 1 that is slidingly coupled is not reversed.

Then, the user rotates the upper plate 1 around the rotating shaft 120 of the housing 110 to set the proper angle suitable for them. The engagement members 140 and 150 may be engaged at multiple angles by the engagement protrusions 145 and 155 formed on the front surface.

In addition, the groove 113 is formed at a predetermined interval along the outer surface of the second elastic member 170 and the elastic support member 190 fixed to insert a portion of the body in the groove 113 inside the housing 110. When is installed, the elastic support member 190 is always caught in the groove 113 to be in a state of elastically supporting the housing 110, so that the housing 110 is not arbitrarily rotated by its own weight in the initial state in which the engagement is released. Therefore, the angle of the upper plate 1 can be set very easily.

When the distance and angle of the upper plate 1 is set, the operation lever 130 is rotated to one side. When the operating lever 130 is rotated, the rotating shaft 120 bolted to the operating lever 130 is rotated, and a bending flange installed inside the hub 180 and the second engagement member 150 along the rotating shaft 120 ( 160 is rotated at the same time.

The bent flange 160 is in close contact with the wall surface of the housing 110 by the elastic member 170 is rotated in a recessed state in the recessed surface 152 of the second engagement member 150, and then the protrusion 161 of the bottom bottom ) Is naturally positioned above the protrusion 154 of the accommodation groove 153 along the cutouts formed at both sides of the protrusion 154 of the accommodation groove 153. At this time, the top of the bending flange 160 is raised from the recessed surface 152 of the second engagement member 150.

When the top of the bending flange 160 is raised from the recessed portion, the second engagement member 150 is pushed toward the first engagement member 140 by the distance where the bending flange 160 is raised and the first engagement member 140. Are matched. At this time, the protrusion 161 of the second engagement member 150 is inserted into the recess 113 of the housing 110 and the elastic member 170 is compressed. When the engagement between the engagement member (140,150) is made, the first engagement member 140 fixed to the support frame 2 and the second engagement member 150 fixed to the housing 110 is not made, so the top plate (1) ) Rotation stops.

At the same time, when the fitting members 140 and 150 are engaged, the hub 180 passing through the cutout 116 of the housing 110 when the top of the bending flange 160 protrudes may increase the thickness of the cutout 116. By passing the incision 116 to the outside of the housing 110, the housing 110 is stably fixed in the compressed state on the inside of the guide rail (200).

Then, when the user rotates the operation lever 130 in the opposite direction, the above process is reversed to return to the initial state while the engagement is released. At this time, the coupling members 140 and 150 are spaced apart by the elastic force of the elastic member 170 that is compressed in the coupling process, and the cutout 116 of the housing 110 that is pushed out is restored to its original position and thus, the upper plate 1 The angle of rotation and the sliding movement of the upper plate 1 is free.

At this time, the user adjusts the angle while rotating the upper plate (1) or adjusts the distance with the user while sliding the upper plate (1) and then rotates the operation lever 130 to one side to refit the engagement members (140,150). The position of the upper plate 1 can be freely changed.

On the other hand, the protrusion 161 for supporting the lower end of the housing 110 is formed on the outer side of the first engagement member 140, or is inserted into the end of the rotating shaft 120 is fitted into the through hole of the housing 110 When the support protrusion 116 is further provided on the outer side of the housing 110 to be supported by the reinforcing cap 175 and the reinforcing cap 175, the through hole of the housing 110 in which the impact generated from the upper side is weak in strength. Since the shock is transmitted to the support part 146 or the reinforcing cap 175 through the lower end portion or the support protrusion 116 of the housing 110 without being concentrated on the 110a, damage to the housing 110 may be prevented.

According to the upper plate variable device of the lecture desk according to the present invention configured as described above, according to the rotation direction of the operating lever operated by the user, the engagement of the engaging member connected to the top plate and the support frame, respectively, made of a multi-angle angle of the top plate In addition to freely adjusting the distance between the user through the guide rail installed between the top plate and the upper housing, the user can freely adjust the angle and distance of the top plate with a simple operation while sitting at the desk Learning to improve the learning efficiency can work on the right posture.

Although the present invention has been illustrated and described in connection with specific embodiments, the present invention may be variously modified and changed without departing from the spirit or the field of the present invention provided by the following utility model registration claims. It should also be included in the scope of the present invention.

1 is a perspective view showing a conventional lecture desk.

Figure 2 is a state of use of the upper plate variable device of the lecture desk according to the present invention.

Figure 3 is an exploded perspective view of the upper plate variable device of the lecture desk according to the present invention.

Figure 4 is a front view of the housing constituting the present invention.

Figure 5 is a front view of the first engagement member constituting the present invention.

Figure 6 is a front view of the second engagement member constituting the present invention.

Figure 7a and 7b is a front view and a side view respectively showing the bending flange of the present invention.

8 is a cross-sectional view showing a coupling state of the first engagement member and the second engagement member of the present invention.

9A and 9B are front and longitudinal cross-sectional views respectively showing the hub of the present invention.

10 is a cross-sectional view showing a state in which the housing is coupled to the guide rail of the present invention.

Figure 11a and 11b is a view showing the internal state of the housing before and after the engagement of the engagement member constituting the present invention, respectively.

<Explanation of symbols for the main parts of the drawings>

100 ... variable 110 ... housing

113 Groove 115 Vertical improvement

116 ... incision 120 ... rotation shaft

130 ... operating lever 140 ... first engagement member

145,155 ... Matching protrusion 146 ... Support

150 ... second engagement member 151 ... insertion protrusion

152 ... indent 153 ... receiving groove

154,161 ... protrusion 160 ... flexible flange

170.elastic member 180.hub

181 Vertical flange 190 Elastic support member

200 ... Information rail 210 ... Jagged groove

Claims (10)

In the variable desk of the lecture desk having a top plate made of a predetermined shape for placing a book or writing, and a support frame for supporting the top plate at a constant height from the floor, A housing coupled to both lower sides of the upper plate and provided with a rotating shaft penetrating horizontally therein; An operation lever fixed to the end of the rotation shaft to the outside of the housing to rotate the rotation shaft; A first engagement member fitted to a rotation shaft to be in close contact with one side of the housing and fixed to an upper end of the support frame; A second engagement member fitted to the rotation shaft to be in close contact with the other side of the housing, rotated together with the housing, and engaged with the first engagement member at various angles by sliding reciprocating along a rotation axis; And a coupling means installed between the first and second engagement members to selectively engage or space the engagement members according to the rotational direction of the operation lever. The method of claim 1, The coupling means A bent flange installed on the housing facing surface of the second engagement member to rotate together with the rotational shaft and to be raised at one side of the second engagement member to move the second engagement member to the first engagement member side to achieve engagement; And The upper plate variable device of the lecture desk, characterized in that composed of an elastic member which is installed between the engaging members to provide a force to the spaced engagement members are spaced apart. The method of claim 1, An insertion protrusion is inserted into the housing surface on the housing facing surface of the second engagement member, and the insertion protrusion is inserted into the inner surface of the housing so that the second engagement member can enter and exit the inside of the housing through the insertion protrusion. Top plate variable device of the lecture desk, characterized in that the groove is formed extending to the bottom of the housing. The method of claim 2, A protrusion having a predetermined height is formed at the bottom of the top of the bent portion of the bent flange, and a protrusion formed at the bottom of the depression surface along the rotational track of the bent flange recessed surface and the protrusion of the bent flange at the center of the housing facing surface of the second engagement member. The receiving groove and the projection formed at a predetermined height from the bottom of the receiving groove is formed, When the projection of the bending flange passes through the projection formed in the receiving groove of the receiving desk characterized in that the projection of the bending flange is located on the upper portion of the projection of the receiving groove so as to be raised from the housing facing surface of the second engagement member. Top Variable. The method of claim 1, In the second engagement member grooves toward the center of the engagement member along the outer circumferential surface is formed at a predetermined interval, At least one elastic support member is fixed to one side of the housing opposite to the groove so that at least one elastic support member is inserted into the groove to prevent the housing from being rotated by its own weight when the fitting member is not engaged. Desk top variable. The method of claim 1, The outer plate of the first desk member is characterized in that the support plate protruding along the movement trajectory of the lower end of the housing to support the housing when an impact from the top is further formed. The method of claim 1, The upper plate variable device of the lecture desk, characterized in that the hub is provided in close contact between the housing and the first engagement member to rotate together with the rotary shaft to limit the rotation section of the rotary shaft. The method of claim 1, And the housing is fixed to the lower portion of the upper plate in the front-rear direction and slidingly coupled with the upper plate through a guide rail fitted to the upper outer side of the housing. The method according to claim 7 or 8, The housing has an incision formed on the one side by a pair of vertical incision line formed from the upper end of the housing, the hub further includes a vertical flange extending from the outer peripheral surface to be in close contact with the incision; The cutout is pushed by the vertical flange when engaging the projecting to the outside of the housing is formed so that the thickness is gradually increased along the rotational direction of the hub so that the housing is pressed and fixed to the inside of the guide rail, the upper plate of the lecture desk Variable device. The method of claim 9, Locking grooves are formed at a predetermined interval inside the guide rails so that the guide rails and the housing are slidably coupled in multiple stages, and an upper portion of the housing is fixed to an elastic support member in which the body is inserted into the locking grooves. Top plate variable device of the lecture desk characterized in that.