KR101274542B1

KR101274542B1 - Reading stand having enhanced usability structures

Info

Publication number: KR101274542B1
Application number: KR1020130005280A
Authority: KR
Inventors: 강건희
Original assignee: 강건희
Priority date: 2013-01-17
Filing date: 2013-01-17
Publication date: 2013-06-18

Abstract

The present invention relates to a reading table having an improved usability structure for improved user convenience, such as readability and portability of a mounted book. The reading stand of the present invention has a folding member which is folded in left and right half and spread so as to be stored in a folded state or supported by an open state, and a slide groove is formed at an upper end thereof, and a lamp receiving groove is formed at an upper side thereof. It includes a built-in pedestal. In addition, the reading table of the present invention is a lamp which is stored in the lamp receiving groove and pulled out to illuminate a book placed on the pedestal, a horizontal movable member inserted into the slide groove of the pedestal to move horizontally, perpendicular to the horizontal movable member Rotating coupled to the vertical movable member coupled to the movable member, and the first hinge axis to the lamp to adjust the lighting angle of the lamp, and coupled to the vertical movable member to the second hinge axis to adjust the angle relative to the upper end of the pedestal It comprises a lighting device having a support member.

Description

Reading stand having enhanced usability structures

The present invention relates to a reading stand, and more particularly, to a reading stand having an improved usability structure for use by a user such as readability and portability of a mounted book.

In general, when reading a book, a reading stand is used as a means for placing and reading a book to alleviate the inconvenience of holding or supporting a book by hand.

Looking at the currently developed reading stand, including a function of simply clamping the book on the stand, as described in the following prior art documents, such as a reading stand (Patent Literature 1 and Patent Literature 2) equipped with a light stand, to facilitate There are known reading stands (Patent Literature 3 and Patent Literature 4) having a folding structure, and in addition, a reading stand having a structure capable of adjusting an inclination angle can be easily found.

Among them, the reading table of Patent Literature 1 has a structure in which a telescopic corrugated pipe is installed on an inclined support plate, and the telescopic corrugated pipe has a structure in which a magnifying glass and a light stand are combined, so that the text and pictures of the book mounted on the reading table can be enlarged through a magnifying glass. In addition, the book allows people to read clearly even in dark environments. However, in this reading stand, the magnifying glass and the light stand are supported by the long and thin stretched corrugated pipe so as to be spaced apart greatly from the inclined support plate, which not only occupies a lot of space but also has a disadvantage in that storage and carrying are inconvenient.

In addition, the reading stand of Patent Literature 2 is provided with a lighting member for irradiating light to the mounting plate on which the book is placed so that reading can be performed even in a place where no lighting device is provided, and the hinge can be folded and stored when the reading stand is not in use. Disclosed is a structure in which the mounting plate is folded in half using an axis and a spring. However, even in this reading stand, the lighting member is fixed by a member extending from the center portion of the mounting plate, and there is a problem in that storage and portability are inferior due to a large amount of space due to the height of the pedestal and the support.

On the other hand, the folding reading table of Patent Document 3 is not provided with a lighting device such as that provided in Patent Document 1 or Patent Document 2, but in half by the hinge member to have a minimum volume to improve storage and portability. It is foldable.

Next, the reading table of Patent Literature 4 has a feature that can be used to carry and carry at the same time easy to store by being able to fold and unfold the support plate by installing a connector between a pair of support plates. In addition, in Patent Document 4, although the bookmark is attached to the central support portion provided between the pair of support plates, since the bookmark is connected by a string, only the bookmark function is possible, and the disadvantage of not being able to prevent the bookshelf from being arbitrarily crossed. have.

[Patent Document 1] Republic of Korea Utility Model Registration No. 20-0284788 [Patent Document 2] Republic of Korea Utility Model No. 20-2010-0005963 (Applicant: Yun Poong-an, Name: folding reading desk) [Patent Document 3] Korean Utility Model Registration No. 20-0407154 (Utility Model Holder: Junsang Lee, Name: Foldable Reading Table) [Patent Document 4] Korean Utility Model Registration No. 20-0343463 (Utility Model Holder: Lee Tae-jong, Name: Reading Table)

As described above, the conventional reading stand has useful functions such as a lighting device in addition to the original function of the reading stand for mounting a book, but due to the installation structure of the lighting device, it takes up a lot of space and has inconveniences in storage and carrying. In addition, the conventional reading desk having a folding structure to improve the ease of storage and portability, there is a need for improvement because there is a lack of other convenience devices such as lighting devices or paperweght function.

The present invention was developed to improve these conventional problems, the object of which is to provide a compact structure of the lighting device to improve the readability of the mounted book even in dark conditions, but do not take unnecessary space due to the lighting device In addition, the present invention provides a reading stand having a structure that improves usability and ease of storage and portability.

Another object of the present invention, by having a means for implementing the function of the bookmark and the paperweight at the same time, not only easy to mark the place after reading, but also has a usability enhancement structure that can prevent the bookshelf to randomly fall over during reading It is to provide a reading table.

Reading stand having an improved usability structure of the present invention for achieving the above object is provided with a folding member to fold in left and right half and to be unfolded so that the book can be stored in a folded state or supported in an unfolded state, and a slide groove at the upper end thereof. It is formed and the upper one side includes a pedestal in which the lamp receiving groove is formed. In addition, the reading stand of the present invention, the lamp is stored in the lamp receiving groove is drawn out to illuminate the book placed on the pedestal, the horizontal movable member is inserted into the slide groove of the pedestal and the horizontal movement, the horizontal movement A second hinge shaft on the vertical movable member which is coupled to the vertical movable member so as to be vertically coupled to the member, and is coupled to the first hinge shaft to the lamp to adjust the illumination angle of the lamp, and the angle of the upper end of the pedestal can be adjusted. It comprises a lighting device having a rotating support member coupled to.

In the above configuration, the horizontal movement member of the lighting device is formed with an uneven rail in the vertical direction, the vertical movement member is formed with a coupling groove to which the horizontal movement member is coupled and the vertical movement member in the vertical movement position A stopper may be provided to engage and be fixed to the type rail.

In addition, the reading stand of the present invention, a fastener insertion groove formed in one corner portion of the pedestal, the adjustment screw is installed rotatably in place on the pedestal through the fastener insertion groove, so that the bookshelf can be fitted on one side ' It is made of a 'shape but is coupled to the adjustment screw to loosen or adjust the adjustment screw according to the fastener insertion groove according to the fastener insertion groove according to the thickness of the bookshelf, and the fastener to secure the bookcase to the pedestal at the relative position of the clamp insertion groove It may further include a bookshelf fixing means having a screw insertion groove is formed is formed when the protruding portion of the adjustment screw is inserted when the base is folded.

In addition, in the configuration of the present invention, the lower end portion of the pedestal, may be provided with a lower support member for supporting the lower end of the book placed on the pedestal and a support member receiving groove for receiving the lower support member.

In addition, in the configuration of the present invention, a plurality of support groove insertion grooves having a concentric structure are formed in the rear portion of the support, and each support insertion groove is formed of an elastic ring so as to support the support on a horizontal plane. Is installed rotatably withdrawal, support protrusions for supporting the support so that the support is inclined only at a predetermined angle with respect to the support drawn out from the support insertion groove may be formed in each support insertion groove.

The reading stand of the present invention configured as described above has a compact lighting device that can be stored and drawn out when needed, and can be used as needed. Therefore, it is possible to increase the readability of the book placed on the reading stand even in dark conditions. Rather, it is much easier to store and carry than a reading table equipped with a conventional lighting device.

In addition, the reading stand of the present invention is provided with a bookcase fixing means for implementing the function of the bookmark and the paperweight at the same time, it is not only easy to mark the place where you have read after reading, but also has the effect of preventing the bookshelf from falling arbitrarily during reading. have.

In addition, since the reading stand of the present invention can support the pedestal on which the book is mounted at an appropriate angle by a plurality of supports, there is an effect that can be conveniently read according to the eye angle of the reader.

1 is a perspective view of a state of use of the embodiment of the reading desk according to the present invention.
FIG. 2 is a perspective view showing the embodiment of FIG. 1 in a folded state. FIG.
3 is an exploded perspective view and a partially enlarged view of the lighting apparatus provided in the embodiment of FIG.
4 is a side cross-sectional view of the folded state for the embodiment of FIG. 1.
FIG. 5 is a cross-sectional side view illustrating a state in which the pedestal and the lamp are unfolded from the state of FIG. 4.
6 is a perspective view showing an operation of each component of the configuration for using a reading stand from the state of FIG.
7 is a view showing a state in which the reading stand of the present invention is used at an inclination angle of 30 °.
8 is a view showing the use of the reading stand of the present invention at a 45 ° inclination angle.
9 is a view showing a state in which the reading stand of the present invention is used at a 60 ° inclination angle.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art can understand the present invention without departing from the scope and spirit of the present invention. It is not.

1 is a perspective view showing a state of use of an embodiment of a reading table according to the present invention, Figure 2 is a perspective view showing the embodiment of Figure 1 folded, Figure 3 is an exploded perspective view of the lighting apparatus provided in the embodiment of Figure 1 And a partial enlarged view. The reading table of the embodiment shown in these figures includes a pedestal 100 and a lighting device 200 for illuminating the book B placed on the pedestal 100 as main components, and will be described in detail as follows. .

The pedestal 100 is divided into a first pedestal 110 constituting the left half and a second pedestal 120 constituting the right half while being symmetrical with the first pedestal 110. In addition, since the folding member 130 having a hinge structure is provided at the middle of the first support 110 and the second support 120, the pedestal 100 is folded left and right by using the folding member 130 as a rotating shaft. As a result, the book B placed on the first pedestal 110 and the second pedestal 120 can be folded or supported in an unfolded state.

In particular, a slide groove 100a is formed at the upper ends of the pedestal 100, that is, the first pedestal 110 and the second pedestal 120, and the slider insertion groove 100b having a circular cross-sectional structure is formed at the lower end of the slider groove 100a. ) Is formed. In addition, a lamp receiving groove 100c is formed at one upper side of the pedestal 100 (for example, the upper portion of the first pedestal 110).

The lighting device 200 is composed of a horizontal moving member 210 and a vertical moving member 220 and the lamp 230 and the rotation support member 240, as shown in detail in Figure 3, slides against the pedestal 100 It is configured as follows to enable movement and storage.

First, the horizontal moving member 210 has a horizontal moving plate 211 made of a thinner and flat plate material than the slide groove 100a so as to be inserted into the slide groove 100a of the pedestal 100, and the slide groove ( It is possible to move horizontally along the slide groove (100a) in the state inserted in the (100a). Furthermore, in the present embodiment, a slider 212 having a round rod shape thicker than the slide groove 100a is further formed at the lower end of the horizontal moving member 210, and the slider insertion groove 100b formed at the bottom of the slide groove 100a. The slider 211 is inserted into the slider 211 to allow smoother sliding and prevent the horizontal moving member 210 from being detached from the slide groove 100a. In addition, as shown in FIG. 4, the front and rear surfaces of the horizontal moving plate 211 are formed with uneven rails 211a, respectively, along the vertical direction. The uneven rails of the uneven rails 211a have the same shape as that of the washboard. consist of.

The vertical movement member 220 is coupled to the horizontal movement member 210 to enable vertical movement relative to the horizontal movement member 210 in the slide groove (100a). That is, the vertical movement member 220 is formed with a coupling groove 221 into which the horizontal movement plate 211 of the horizontal movement member 210 is inserted and coupled in the vertical direction, and protrudes toward the inside of the coupling groove 221. A pair of front and rear fixed pieces 222 on which the stop protrusions 222a are formed are provided in a form facing the uneven rail 211a of the horizontal moving member 210. Therefore, in the state where the horizontal plate 211 of the horizontal member 210 is coupled to the vertical member 220 through the defect groove 221, vertical movement of the vertical member 220 in the vertical direction, the vertical In the moved position, the stopping projection 222a of the fixing piece 222 is engaged with the uneven rail 211a to fix the vertical moving member 220. In addition, as can be seen in Figure 4, since the vertical movement member 220 is coupled in close contact with the horizontal movement member 210, the coupling friction force between the horizontal movement member 210 and the vertical movement member 220 acts. Done. Therefore, when the horizontal movement member 210 is moved horizontally when the horizontal movement member 210 is moved horizontally, the horizontal movement member 210 is interlocked with the horizontal movement of the vertical movement member 220 by the combined frictional force. It is possible to move horizontally in the slide groove (100a).

The lamp 230 is a light source that is housed in the lamp receiving groove (100c) formed on the upper side of the pedestal 100 is drawn out to illuminate the book placed on the pedestal 100, a conventional LED lamp may be used. In addition, a battery mounting portion 231 is formed in the rear portion of the lamp 230 as shown in FIG.

The rotation support member 240 is a means for adjusting the illumination angle of the lamp 230, one side of the lamp 230 is coupled to the first hinge shaft 241 to the first hinge shaft 241 It is possible to adjust the angle of the lamp 230 on the rotation support member 240 as a central axis. In addition, in order to be able to adjust the angle of the rotary support member 240 with respect to the upper end of the base 100, the other side of the rotary support member 240 is a vertical movable member 220 and the second hinge shaft 242 Are combined.

On the other hand, by fixing the bookshelf (책 張) of the book placed on the pedestal 100 to the pedestal 100, the paperweight to function as a bookmark to mark the place after the reading and to prevent the bookshelf from falling arbitrarily during reading Bookshelf fixing means 140 that functions as a (文鎭) is provided. This bookcase fixing means 140 is configured as follows.

First, the fastener insertion groove 141 is formed in one corner portion of the pedestal 100. In this embodiment, the fastener insertion groove 141 is formed in the right corner portion of the second support 120. The adjustment screw 142 is installed on the pedestal 100 so that the adjustment screw 142 can be rotated in place. That is, as shown in FIG. 4, the pedestal 100 has a groove 141a which is deeper than the fastener inserting groove 141, and the distal end of the adjustment screw 142 is extended than the main body so that the small groove 141a is formed. By being coupled in, the adjustment screw 142 can be rotated in place without falling out.

In addition, the fastener 143 made of a 'b' shape is provided so that the bookshelf can be fitted to one side is screwed into the adjustment screw 142 is inserted into the fastener insertion groove 141. Accordingly, the fastener 143 enters and exits the fastener insertion groove 141 by loosening or tightening the adjusting screw 142, thereby exposing the fastener insertion groove 141 to correspond to the thickness of the bookcase. The bookcase can be fixed to the thickness.

In addition, the protruding portion of the adjustment screw 142 when the pedestal 100 is folded to the left edge portion of the pedestal 100 (in the present embodiment, the first pedestal 110) at a position opposite to the detent insertion groove 141. Is inserted into the screw insertion groove 144 is inserted.

Next, in order to keep the book B placed on the pedestal 100 to be stably mounted, the lower end of the pedestal 100 supports the lower end of the book B placed on the pedestal 100. The member 150 is provided. In particular, the lower support member 150 is installed as a receptacle, for this purpose, a lower support member receiving groove (100d) is formed in the lower end of the pedestal 100 is accommodated.

On the other hand, the back portion of the pedestal 100 is provided with a first to third support (161, 162, 163) for supporting the pedestal 100 in a state inclined at a predetermined angle in accordance with the angle of the line of sight at the time of reading. In the present invention, these supports (161, 162, 163) are provided for each inclination angle (30 °, 45 °, 60 °) of the pedestal 100. That is, the first to third support insertion grooves 100e, 100f, and 100g of concentric structures are formed in the rear portions of the first support 110 and the second support 120, respectively. Supports 161, 162, and 163 made of an elastic ring such as spring steel are rotatably installed on the pedestals 100e, 100f, and 100g, respectively, to support the pedestals 100: 110, 120 on a horizontal plane. In addition, in each of the support insertion grooves 100e, 100f, and 100g, the support supports 161, 162, 163 drawn out from the support insertion grooves 100e, 100f, and 100g are supported in a state of maintaining a predetermined angle with the pedestal 100. The projections 100h, 100i, and 100j are formed.

Next will be described the operation of the reading table according to an embodiment of the present invention configured as described above.

First, Figure 4 is a side cross-sectional view of the folded state of the embodiment of the reading table according to the present invention, showing a state in which the first pedestal 110 and the second pedestal 120 of the pedestal 100 is folded. In this state, the slider 212 of the lighting device 200 is inserted into the slider insertion groove 100b of the second support 120 and the horizontal moving member 210 and the vertical moving member 220 are coupled together. It is inserted into the slide groove 100a. In addition, the rotation supporting member 240 coupled to the vertical moving member 220 by the second hinge shaft 242 is folded in a state in which the upper surface of the pedestal 100 is in parallel abutment. In addition, the lamp 230 coupled to the rotation support member 240 by the first hinge shaft 241 is accommodated in a folded state in the lamp receiving groove 100c of the first base 110.

Meanwhile, the fastener 143 of the bookshelf fixing means 140 is inserted into the fastener inserting groove 141 of the second support 120, and the adjustment screw for operating the fastener 143 against the fastener inserting groove 141. The head part is inserted into the screw insertion groove 144 in a state in which 142 is engaged with the fixing clamp 143. In addition, the lower support member 150 located at the lower end of the pedestal 100 is accommodated in the support member accommodating groove 100d of the pedestal 100, and the first to third supports 161, 162 and 163 are provided at the back of the pedestal 100. Is inserted into the first to third support insertion grooves 100e, 100f, and 100g.

In order to use the reading stand in the above state, as shown in FIGS. 5 and 6, the lower support member 150 is supported by the lower support member 150 in the extended state of the first support 110 and the second support 120. Sliding out from it, the desired support (161, 162, 163 any one of the 161, 162, 163) as shown in any one of Figures 7 to 9 extend from the support insert groove (100e, 100f, 100g), and then the first support The book is mounted on the 110 and the second pedestal 120 and the lower support member 150.

And, if you want to use the lighting device 200, withdraw the lamp 230 from the lamp receiving groove (100c) of the first pedestal 110, and then as shown in Figure 6 and 7 the horizontal moving member ( The vertical moving member 220 is slid upwardly with respect to 210 to withdraw from the slide groove 100a. At this time, the stop protrusion 222a formed on the vertical moving member 220 is engaged with the uneven rail 211a formed on the horizontal moving plate 211 of the horizontal moving member 210, so that the vertical moving member 220 is not drawn back into the slide groove (100a) by its own weight. Subsequently, the illumination position of the lamp 230 is set by sliding the horizontal movable member 210 along the slide groove 100a of the first pedestal 110 and the second pedestal 120, as shown in FIG. Since the coupling friction force acts in close contact between the moving member 210 and the vertical moving member 220, the horizontal moving member 210 moves horizontally in conjunction with the vertical moving member 220 moving in the horizontal direction. Subsequently, the lamp 230 and the rotation support member 240 are rotated with the first hinge axis 241 and the second hinge axis 242 as the rotation center axis to set the illumination direction of the lamp 230 in a desired direction. .

In order to mark the place where the reading is finished after reading or to prevent the bookshelf from being arbitrarily skipped during reading, the bookshelf fixing means 140 is used as shown in FIG. 7. That is, when the adjustment screw 142 of the bookshelf fixing means 140 is rotated in the forward direction, the adjustment screw 142 is coupled to the adjustment screw 142 as it rotates in place while being coupled to the second pedestal 120. The 'b' shaped fastener 143 is drawn out from the fastener insertion groove 141, and when the adjusting screw 142 is rotated in the reverse direction, the fastener 143 is introduced into the fastener insertion groove 141 again. Therefore, after adjusting the withdrawal height of the fastener 143 to match the thickness of the bookshelf, and then insert the bookshelf into the 'b' shaped groove of the fastener 143 as shown in Figure 1 rotate the adjustment screw 142 in the reverse direction When the clamp 143 is to press the bookcase is fixed to the bookcase. In addition, when the first support 110 and the second support 120 are folded to each other, it is adjusted to the screw insertion groove 144 formed in the first support 110 at a position corresponding to the fastener insertion groove 141. Since the protruding portion of the screw 142 is inserted, it is possible to prevent the gap between the pedestal (100: 110, 120).

On the other hand, if you want to adjust the inclination angle of the pedestal 100 according to the eye angle of the reader of the first to third support (161, 162, 163) provided in the back portion of the first pedestal 110 and the second pedestal 120, respectively Choose which one to use. In the present embodiment, the first support 161 is designed to tilt the pedestals 100: 110 and 120 by 30 °, and the second support 162 may be tilted by 45 ° and the third support 163 by 60 °. It is designed to be. First, FIG. 7 shows a state in which the first support 161 is unfolded from the first support insertion groove 100e of the pedestal 100. The first support is maintained so that the pedestal 100 is inclined by only 30 °. The support protrusion 100h provided in the insertion groove 100e supports the first support 161. Similarly, FIG. 8 shows a state in which the support protrusion 100i provided in the second support insertion groove 100f supports the second support 162 so that the pedestal 100 is kept inclined by only 45 °. 9 shows a state in which the support protrusion 100j provided in the third support insertion groove 100g supports the third support 163 so that the pedestal 100 is kept inclined by only 60 °. Giving. Since the first to third supports 161, 162 and 163 are made of an elastic ring such as spring steel, the first to third supports 161, 162 and 163 are supported by applying a force to retract into the support insertion grooves 100e, 100f and 100g. It is folded while being elastically deformed with respect to the protrusions 100h, 100i, and 100j.

As described above, since the reading stand of the present invention includes a lighting device having a compact structure that can be stored in the pedestal 100 and can be pulled out when necessary, it can be compared with a reading stand having a conventional lighting device. It can be seen that it is much easier to store and carry.

In addition, the reading stand of the present invention is equipped with a bookcase fixing means 140 for implementing the function of a bookmark and a paperweight at the same time, it is not only easy to mark the place where you have read after reading, but also to prevent the bookshelf from falling arbitrarily during reading. have.

In addition, the reading stand of the present invention can support the pedestal on which the book is mounted at an appropriate angle by using a plurality of supports, so that the reading stand can be conveniently read according to the eye angle of the reader.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

100: base 100a: slide groove
100b: Slider insert groove 100c: Lamp storage groove
100d: Support member receiving groove 100e, 100f, 100g: Support insert groove
100h, 100i, 100j: support protrusion 110: 1st base
120: second base 130: folding member
140: bookcase fixing means 141: clamping groove
142: adjusting screw 143: clamp
144: screw insertion groove 150: bottom support member
161: first support 162: second support
163: third support 200: lighting device
210: horizontal moving member 211: horizontal moving plate
211a: uneven rail 212: slider
220: vertical moving member 221: coupling groove
222: fixed piece 222a: stopper
230: lamp 240: rotation support member
241: first hinge axis 242: second hinge axis
B: book

Claims

A folding member having a folding member configured to be folded in a left and right half so as to be stored in a folded state or supported in an open state, and having a slide groove formed at an upper end thereof, and a lamp receiving groove formed at an upper side thereof;
A lamp which is stored in the lamp accommodating groove and is drawn out to illuminate a book placed on the pedestal, a horizontal movable member inserted into the slide groove of the pedestal to move horizontally, and vertically coupled to the horizontal movable member Rotating support coupled to the vertical movable member and a second hinge axis to the vertical movement member to be coupled to the first hinge axis to the lamp to adjust the angle of illumination of the lamp and to adjust the angle relative to the upper end of the pedestal A reading desk having an ease of use structure including a lighting device having a member.

The method of claim 1,
Concave-convex rail is formed along the vertical direction in the horizontal moving member of the lighting device,
The vertical movement member is provided with a coupling groove to which the horizontal movement member is coupled, and a stop protrusion for locking and fixing to the uneven rail at the vertical movement position of the vertical movement member is provided. Reading stand with frame.

The method of claim 1,
A fastener inserting groove formed at one corner of the pedestal;
An adjustment screw rotatably installed in place on the pedestal through the clamp insertion groove;
A fastener which is formed in a 'b' shape so that the bookcase can be fitted to one side, and is fixed to the thickness of the bookcase by being coupled with the adjusting screw and entering or exiting the fastener inserting groove according to loosening or tightening the adjusting screw;
The bookcase fixing means further comprises a bookshelf fixing means formed on the pedestal at the relative position of the fastener insertion groove and having a screw insertion groove into which the protruding portion of the adjustment screw is inserted when the pedestal is folded. Reading table with a book.

The method of claim 1,
The lower end of the pedestal, the lower support member for supporting the lower end of the book placed on the pedestal and the support member receiving groove for receiving the lower support member, characterized in that the reading table having a usability improvement structure.

The method of claim 1,
A plurality of concentric support insertion slots are formed in the rear portion of the pedestal,
Each support insertion groove is provided with a support made of an elastic ring rotatable to support the support on a horizontal plane,
And a support protrusion for supporting the support so that the support is inclined at a predetermined angle with respect to the support drawn out from the support insertion groove is formed in each of the support insertion grooves.