JP2001242559A - Opening and closing device of pressure plate for document - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost and the material cost of an opening and closing device by enabling energization of a lift member to the oscillating member side, without forming a notch in the tip part of the oscillating member, in an opening and closing device of a pressure plate for document with which lifts up the pressure plate. SOLUTION: The opening and closing device 1 of the pressure plate for document is equipped with a base member 6 mountable on the upper surface of a document placing plate 3, the oscillating member 7 whose base end is pivotally fitted to the base member 6 so as to enabling vertical oscillation, the lift member 8 which is pivotally fitted to the tip part of the oscillating member 7 so as to overlap the upper surface side of the member, and can attach the pressure plate for document 5 covering the document placing plate 3 from above, and an energizing member 9 housed inside the oscillating member 7, on the outer side of the longitudinal direction in a stretched state, having a first cam part 27 at the base end side which energizes the oscillating member 7 upwards and a second cam part 30 at the front end side which energizes the lift member 8 in the direction which laps with the oscillating member 7. A pendent wall 36 extending downward at the tip part of the lift member 8 is formed, and a part to be pressed 38 on which the second cam part 30 of the energizing member 9 abuts is provided on the pendent wall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift-up type opening / closing device for an original pressing plate used in a copying machine, a printing machine or the like.

[0002]

2. Description of the Related Art Conventionally, in order to properly cover a thick original such as a dictionary or a picture book, the rear end of the original pressing plate is lifted to lift the rear end of the original pressing plate. 2. Description of the Related Art A lift-up type document pressing plate opening / closing device capable of swinging a front end portion downward is known. And
As such a lift-up type opening / closing device, a base member attachable to the upper surface of the document table, and a base end portion pivotally attached to the base member so as to be able to swing up and down in a state of being urged upward, and a document pressing plate A swingable member that can be attached, and a cylindrical support leg projecting downward from the lower surface of the base member are provided. The support leg is slid into a vertical insertion hole provided on the upper surface of the document table. There is a type in which the base member itself is lifted up by being freely inserted (for example, Japanese Utility Model Publication No. 4-28094, Japanese Utility Model Publication No.
-49338).

However, in the case of a type in which the support legs are inserted into the insertion holes on the document table side and the base member is lifted up, the support legs are always kneaded inside the insertion holes due to the front-rear reaction force received from the base members. In this state, the outer peripheral surface of the support leg is in contact with the inner wall of the insertion hole with a considerably large frictional force, so that it is difficult to slide. For this reason, particularly in the case of a heavy original pressure plate having an automatic document feed function, there is a disadvantage that the pressure plate is extremely difficult to lift up. Therefore, a lift member is further pivotally attached to the tip of the swinging member so as to overlap with the upper surface side of the swing member, and a document pressing plate is attached to the lift member, so that the document can be pressed without moving the base member itself up and down. An opening / closing device that lifts a plate has already been proposed (see Japanese Utility Model Registration No. 2598506 (hereinafter, this publication is referred to as a conventional publication)).

That is, such a conventional opening / closing device includes a base member which can be mounted on the upper surface of a document table, a swing member having a base end pivotally attached to the base member so as to be vertically swingable, and A lift member pivotally attached to the leading end of the member so as to overlap the upper surface of the member and to which a document pressure plate that covers the document table from above can be attached, and a state in which the swing member is extended outward in the longitudinal direction thereof. And a biasing member having a base end side first cam portion for biasing the swinging member upward and a distal end side second cam portion for biasing the lift member in a direction overlapping the swinging member. And with.

[0005]

In the opening / closing device described in the above-mentioned conventional publication, a pressed portion (conventionally known) for urging the lift member toward the swing member by bringing the second cam portion of the urging member into contact. Since the “operating member 11” described in the publication is constituted by a shaft spanned between the left and right side plates of the lift member, the tip of the both side surface plates of the swing member allows the shaft to turn. (See Claim 1 in the claims of the related art (column 2, lines 2 to 3 of the same publication)).

As described above, in the opening / closing device described in the conventional publication, it is necessary to form a notch for escaping the shaft at the tip of the both side plates of the rocking member. The shape becomes complicated and the manufacturing cost of the switchgear increases, and unless the thickness of the swinging member itself is considerably increased, the supporting strength of the tip end of the member cannot be secured. There is a disadvantage that the material cost is high. The present invention relates to an opening / closing device for a document pressure plate that can lift up a document pressure plate without moving a base member up and down, and in which the lift member is moved to the rocking member side without forming a notch at the tip of the rocking member. An object of the present invention is to reduce the manufacturing cost and material cost of the switchgear by enabling the biasing.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention has taken the following technical means. That is, according to the present invention, in the opening / closing device for the original cover, a downwardly extending hanging wall is formed at a tip end portion of the lift member, and a pressed portion to which the second cam portion of the urging member abuts is formed on the hanging wall. It is characterized by being formed. In this case, the pressed portion that the second cam portion of the biasing member contacts is formed on a hanging wall that extends downward to the distal end portion of the lift member, so that the pressed portion is separated from the left and right side plates of the lift member. It is possible to arrange the lift member on the swing member side without forming an escape cutout at the tip of the swing member to allow the pressed portion to pivot. Be able to energize.

Accordingly, the shape of the tip of the swinging member can be simplified because there is no need to form the notch, and the manufacturing cost of the switchgear can be reduced in this respect. Also, since the notch does not have to be formed in the swing member,
The supporting strength of the swinging member can be effectively secured without particularly increasing the plate thickness of the swinging member itself, and in this regard, the material cost of the switchgear can be reduced. In the opening and closing device of the present invention described above, the pressed portion may be formed by bending the hanging wall itself (see FIG. 1), or may be formed separately from the hanging wall on the inner surface side of the hanging wall. (See FIG. 6), but the former is preferred because the number of components can be reduced and the structure of the tip end of the lift member becomes simpler.

In the former case, if the pressed portion is formed by curving the lower end portion of the hanging wall inward in a curl shape, the pressed portion abuts on the second cam portion. Since the surface becomes a curved surface, the sliding of the pressed portion against the second cam portion becomes smooth, and the wear of the second cam portion can be reduced as much as possible, and the pressed portion bent and formed in the curl shape. The bending strength of the hanging wall can be increased. On the other hand, in the switchgear described in the above-mentioned conventional gazette (utility model registration No. 2598506 gazette),
The base member includes a fixed base (mounting member 4) having a mounting plate for the document table, and a cam member (cam member 8) fixed to the fixed base and having a lift cam surface with which the first cam portion of the urging member abuts. These two members are integrated with each other by two pins passing through them.

However, when both the cam member and the fixed base are penetrated by two pins as described above, and the two are integrated, the fixed base having another shape different from that of the original mounting table according to the change of the specification of the document table. If it is necessary to replace the fixed base, it is necessary to remove the two pins once, replace the fixed base, and then insert the two pins again, which is very troublesome to replace the fixed base. There is.
Also, in the case of a configuration in which the cam member and the fixed base are integrated,
There is also a disadvantage that the fixed base cannot be abolished for the purpose of cost reduction.

Accordingly, the present invention relates to an opening / closing device having a base member on which a swinging member for supporting a document pressing plate is pivotably movable up and down and which can be mounted on the upper surface of a document placing table. A fixed base having a mounting plate with respect to the upper surface of the mounting table, and a cam member having a lift cam surface fixed to the fixed base so as to be separable and in contact with a first cam portion of an urging member, and a swing member. The pivot shaft for pivoting is not inserted through the fixed base but is inserted only through the cam member. In this case, since the rocking shaft is inserted only into the cam member without being inserted into the fixed base, the fixed base can be removed from the cam member without removing the rocking shaft.
The operation of replacing the fixed base with the change in the specification of the document table can be performed extremely easily, and the fixed base can be abolished in order to cope with recycling or reuse.

On the other hand, a cam member having a lift cam surface with which a first cam portion of an urging member for urging the swinging member upward comes into contact is provided on a base member attachable to the upper surface of the document table. In the opening and closing device, it is necessary to apply lubricating grease to the lift cam surface in order to smoothly slide the first cam portion on the lift cam surface. Conventionally, however, the lift cam surface is processed into a smooth and smooth surface, so the lubricating grease is gradually scraped by the first cam portion on the upper and lower sides of the lift cam surface while the swing member repeatedly swings up and down. May be used.

When the scraping phenomenon occurs, the lubrication at the central portion of the lift cam surface gradually decreases, and noise is generated due to the sliding of the first cam portion, and the gathered lubricating grease is collected. May be attached to the manuscript or the clothes of the user during copying or the like, and may stain them. In view of the above, the present invention provides an opening / closing device including a cam member having a lift cam surface with which the first cam portion abuts, and has a function of retaining lubricating grease on the lift cam surface, the abutment surface of the first cam portion, or both. It is recommended that you carry out fine unevenness processing.

In this case, since the lift cam surface (or the first cam portion) is subjected to fine unevenness having a function of retaining lubricating grease, even if the swing member repeatedly swings up and down,
Lubricating grease is prevented from being swept up and down on both sides of the lift cam surface. For this reason, it is possible to prevent the generation of noise due to the decrease in the lubrication degree, and it is possible to effectively prevent the accumulation of the lubricating grease from adhering to the document or the clothes. Furthermore, in the case of a document pressure plate having an automatic document feed function, in particular, static electricity generated at the time of document feed may cause a malfunction in electrical control, so that a reliable grounding measure is required. Therefore, means for connecting the swing member and the base member with an earth cord made of a metal wire having good conductivity has been adopted. However, in this case, both terminals of the earth cord need to be screwed to both members. The manufacturing cost may be increased, or the ground cord may be broken due to repeated opening and closing operations of the hinge.

Therefore, in the present invention, by providing a grounding member having an excellent conductive spring force, one end of which is fixed to one of the base member and the swinging member, and the other end of which is always in sliding contact with the other. The above grounding measures are taken.
In this case, since the grounding member has a spring force that always slides against the base member or the swinging member, it is sufficient to fix one end of the grounding member with a screw or the like, thereby reducing the manufacturing cost required for grounding measures. Therefore, it is possible to prevent a trouble such as the ground cord breakage as described above.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 shows the opening / closing device 1 of the present embodiment.
Is shown at the top of the copying machine 2 employing
The document mounting table 3, a document pressing plate 5 that presses the mounting surface 4 of the mounting table 3 from above, and a rear end of the pressing plate 5 slidably up and down on the rear of the upper surface of the document mounting table 4. The opening and closing device 1 for pivotal connection. As shown in FIGS. 1 to 5, the opening / closing device 1 of the present embodiment has a base member 6 attachable to the upper surface of the document table 3, and a base end pivotally attached to the base member 6 so as to be vertically swingable. And a lift member 8 having a mounting portion (a mounting plate 33 to be described later) pivotally attached to the distal end of the rocking member 7 so as to overlap the upper surface of the rocking member 7 and attached to the original cover 5. And a biasing member 9 housed inside the swinging member 7 in a state of being stretched outward in the longitudinal direction.

Among them, the base member 6 is used for the document table 3.
A fixed base 11 having a mounting plate 10 for the upper surface of
The lift cam surface 12 which is detachably fixed to the fixed base 11 and contacts the first cam portion 27 of the urging member 9 described later.
And a cam member 13 having: As shown in FIG. 5, the fixed base 11 integrally includes the mounting plate 10, a supporting side wall 14 having left and right sides bent upward, and a rear wall 15 having a rear end bent upward. A semi-circular support recess 16 having an upward opening shape is formed at the rear upper end of each support side wall 14.
The opening direction of the support recess 16 may be forward or another direction.

The cam member 13 is made of a synthetic resin block having the lift cam surface 12 on the front side of the upper surface.
A short columnar boss 1 is provided on both left and right sides of the cam member 13.
7 are integrally protruded. At the rear of the cam member 13,
A single rocking shaft 18 that supports the base end of the rocking member 7 so as to be vertically rockable is inserted therethrough. The rocking shaft 18 is disposed so as to pass through the center of each boss 17. ing. As shown in FIG. 5, the cam member 13 is fitted into the fixed base 11 with the lower half thereof sandwiched between the two supporting side walls 14, and the fixing screw 19 screwed from the lower surface side of the mounting plate 10 (FIG. 1). Reference) to the fixed base 11. Each boss 17 of the cam member 13 is fitted into the support recess 16 of each of the support side walls 14 from above, thereby preventing the swing shaft 18 from passing through the support side wall 14 of the fixed base 11. Cam member 1
3 only.

Therefore, in the case of the base member 6 of the present embodiment, the fixed base 1 can be removed without removing the swing shaft 18.
1 can be removed from the cam member 13,
The replacement work of the fixed base 11 according to the change of the specification of the document table 3 can be performed extremely easily. As shown in FIG. 1, the lift cam surface 12 of the cam member 13 is formed into a curved surface in which the radius of curvature from the swing shaft 18 gradually increases toward the front (to the left in FIG. 1). The swinging member 7 is always urged upward by pressing the first cam portion 27 of the urging member 9 in a compressed state described later against the oscillating member 12.

As shown in FIGS. 3 to 5, the swing member 7 is
The side plate 22 is bent from both left and right sides of the back plate 21 and is made of a steel plate having a substantially U-shaped cross section.
8 is prevented from slipping out by a ring washer through the protruding end of the cam member 1 of the base member 6.
3 is pivotally mounted so as to be vertically swingable. Each side plate 2
A slide flange 23 whose edge is bent inwardly is provided at the lower end edge of 2, and is partitioned between the slide flange 23 and the back plate 21 and between the both side plates 22. The urging member 9 is housed in a space having a rectangular cross section.

As shown in FIGS. 1 to 3, the urging member 9 of the present embodiment is provided at the base end side inside the swinging member 7 (right side in FIG. 1).
, And a second slider 25 located on the front end side (left side in FIG. 1) of the first slider 24, and are interposed between them in a compressed state and parallel in the width direction in the swinging member 7. And a total of three coil springs 26. Among these, the first slider 24 has a first cam portion 27 on the base end side that comes into contact with the lift cam surface 12, and has three storage recesses 28 opened on the front end side inside, made of a synthetic resin block. The second slider 25 is made of a synthetic resin having three housing recesses 29 that open on the base end side, and a second cam portion 30 that contacts a pressed portion 38 described later on the front end side. It consists of a block body made of.

Each of the sliders 24, 25 is provided with a swinging member 7 with its storage recesses 28, 29 facing each other.
Are housed in the space within the swinging member 7 so as to be slidable in the longitudinal direction (the left-right direction in FIG. 1).
In addition, as shown in FIG. 1, the first cam portion 27 is formed of a ridge having a substantially semicircular cross section, and the second cam portion 30 is slightly moved toward the base end side (left side in FIG. 1) toward the lower side. It is constituted by an inclined wall that is inclined. The three coil springs 26, which cause the elastic force of the urging member 9, are stored in the storage recesses 28, 29 of the sliders 24, 25, respectively, so that the sliders 24, 25 are compressed. The first cam portion 27 is always pressed against the lift cam surface 12 by the elastic force of the coil spring 26 in the compressed state, and the second cam portion 30 is always pressed against a pressed portion 38 described later. It has become.

A lift shaft 31 is erected on both ends of the side plate 22 of the swinging member 7, and the tip of the lift member 8 is pivotally mounted on the lift shaft 31. As shown in FIGS. 4 and 5, the lift member 8 includes a casing 32 having a U-shaped cross section that can just surround the swing member 7,
And a rectangular mounting plate 33 integrally bent from both left and right sides of the casing 32. The casing 32 of the lift member 8 includes a back plate 34 and side plates 35 bent on both left and right sides of the back plate 34.
And a hanging wall 36 bent from the front end of the back plate 34. This lift member 8
A front end (left end in FIG. 1) of both side plates 35 of the casing 32 is mounted on a distal end of the swing member 7 so that a rear part (right end in FIG. 1) can move up and down. Both ends of the lift shaft 31 are inserted.

When the lift member 8 swings downward around the lift shaft 31 and approaches the swing member 7, the back plate 34 of the lift member 8 overlaps the upper surface of the back plate 21 of the swing member 7. At this time, the swing member 7 is housed in the casing 32 of the lift member 8. Also,
The lift member 8 connects the mounting plate 33 to the original pressing plate 5.
By screwing to a mounting wall 37 (see FIG. 4) formed at the rear end of the crimping plate 5, the mounting plate 37 can be mounted to the crimping plate 5. As shown in FIG. 1 to FIG. 3, a pressed portion 38 with which the second cam portion 30 of the urging member 9 abuts is provided on the hanging wall 36 formed to extend downward at the distal end of the lift member 8. The pressed portion 38 of the present embodiment has the hanging wall 36
Is formed in a curled shape toward the inside of the casing 32.

As described above, in the present embodiment, the hanging wall 36
Since the pressed portion 38 with respect to the second cam portion 30 is formed by bending itself, the number of components can be reduced and the structure of the distal end portion of the lift member 8 can be more simplified. In addition, the pressed portion 38 is the casing 32
, The contact surface with the second cam portion 30 is a curved surface, so that the pressed portion 38 slides smoothly on the second cam portion 30, and the second cam portion 30 can be reduced as much as possible, and the pressed portion 38 which is bent and formed in the curl shape has the hanging wall 3.
6 can be increased in bending strength.

As shown in FIG. 5, the lift cam surface 12 of the cam member 13 is provided with a fine unevenness 40 having a function of retaining lubricating grease, for example, by embossing. The lubricating grease is prevented from being scraped to the upper and lower sides of the lift cam surface 12 even if the upper and lower members 7 repeatedly swing up and down. The fine unevenness processing 40 may be formed on the contact surface of the first cam portion 27. As shown in FIGS. 2 and 5, the supporting member 14 of the fixed base 11 of the base member 6 has a ground member 41 formed of a leaf spring made of a metal plate having good conductivity.
Is fixed, and the tip of the ground member 41 is always in sliding contact with the side plate 22 of the swinging member 7.

In this case, since the grounding member 41 has a spring force for always slidingly contacting the swinging member 7, it is sufficient to fix one end of the grounding member to the base member 6 with a screw or the like. As compared with the case where the members 6 and 7 are connected by an earth cord, the manufacturing cost required for the grounding measure can be reduced. Next, the operation of the switching device 1 according to the above configuration will be described. Since the second cam portion 30 of the urging member 9 presses the pressed portion 38 of the lift member 8, the lift member 8 is constantly urged in a direction overlapping the swinging member 7. The lift member 8 swings up and down together with the swing member 7 unless an external force for pulling the end portion away from the swing member 7 acts.

Therefore, in the case where the original is a thin object such as a single sheet, as the original pressing plate 5 is swung downward and closed, as shown in FIG. When the original pressing plate 5 is closed, the thin original placed on the original placing table 3 is pressed by the pressing plate 5 when the original pressing plate 5 is closed. On the other hand, the first cam portion 27 of the urging member 9 is
, The swinging member 7 is always urged in the direction of swinging upward, and this urging force is given a predetermined swing against the rotational torque around the swing shaft 18 by the weight of the original cover 5. Except for the moving height, they are set to substantially match.

Therefore, when the original cover 5 is rotated upward from the state shown in FIG. 1, the upward rotation of the original cover 5 is assisted by the urging force of the urging member 9, and the original cover is rotated with a light force. 5 can be raised. On the other hand, if the original is a thick original 42 such as a dictionary or a picture book, and the original cover 5 is swung downward and closed, as shown in FIG. When the lift member 8 contacts the original 42, the lift member 8 rotates around the lift shaft 31, and the lift member 8
Since the rear end of the original document 42 is separated from the swinging member 7, the original document 42 can be pressed from above in an appropriate state in which the original cover 5 is parallel to the thick original document 42.

Since the pressed portion 38 is constantly pressed from the second cam portion 30, the original pressing plate 5 is moved from the state shown in FIG.
In the case where the document pressing plate 5 is rotated, the pressing force of the pressing member 9 assists the upward rotation of the pressing plate 5 so that the document pressing plate 5 can be pulled up with a light force. According to the second cam portion 3 of the urging member 9,
0 is pressed against the hanging portion 36 of the lift member 8.
Since the pressed portion 38 is separated from the left and right side plates 35 of the lift member 8, a notch for escape to allow the pressed portion 38 to turn is formed at the tip of the swing member 7. The lift member 8 can be urged toward the swing member 7 side without forming the lift member 8 on the swinging member 7 side.

Therefore, the shape of the tip of the swinging member 7 can be simplified in that there is no need to form a notch for escape,
In this regard, the manufacturing cost of the switchgear 1 can be reduced. Also,
Since such a notch need not be formed in the swinging member 7,
The support strength of the swing member 7 can be effectively secured without particularly increasing the thickness of the swing member 7 itself. Further, according to the opening / closing device 1 of the present embodiment, the shape of the swinging member 7 is simplified without forming a notch for escape. It is possible to prevent troubles such as damage to a part of the human body, and since the leading end of the lift member 8 is closed by the hanging wall 36, a fingertip of a person or a document is not pinched by the leading end of the opening / closing device 1. Thus, safety during operation can be improved.

The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 6, the pressed portion 38 includes a cam body 43 separate from the hanging wall 36 of the lift member 8. It can also be configured. The cam body 43 is fixed to the inner surface of the hanging wall 36, has an insertion portion 44 in which the lift shaft 31 is inserted at an upper end portion, and has a curved surface contact portion 45 with the second cam portion 30 at a lower end portion. Have. However, in the case of the modification shown in FIG. 6, the cam body 43 which is a separate member from the lift member 8 is required, and the number of components is increased, and an operation of fixing the cam body 43 to the hanging wall 36 is required. Since the processing time is increased, it is preferable to form the pressed portion 38 by bending the hanging wall 36 itself as in the above embodiment.

[0033]

As described above, according to the present invention,
Since there is no need to form a notch at the tip of the swinging member to allow the swiveling of the pressed portion, the shape of the tip of the swinging member can be simplified and the manufacturing cost of the opening and closing device can be reduced. In addition, the supporting strength of the swinging member can be secured without increasing the thickness of the swinging member so much, and the material cost of the opening and closing device can be reduced.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view of an opening / closing device when a document pressing plate is in a closed state.

FIG. 2 is a side sectional view of the opening / closing device when the original cover is in an open state;

FIG. 3 is a side cross-sectional view of the opening / closing device when the original cover is in a lift-up state.

FIG. 4 is a front sectional view of the opening / closing device of FIG. 1;

FIG. 5 is an exploded perspective view of the opening / closing device for the original cover.

FIG. 6 is a side sectional view of an opening / closing device for illustrating a modification of a pressed portion.

FIG. 7 is a side view of an upper part of a copying machine employing the opening / closing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 opening / closing device 3 document placing table 5 document pressure plate 6 base member 7 swing member 8 lift member 9 urging member 10 mounting plate 11 fixed base 12 lift cam surface 13 cam member 18 swing shaft 27 first cam portion 30 second cam Part 36 hanging wall 38 pressed part 40 fine unevenness 41 ground member

Claims (6)

[Claims] 1. A base member attachable to the upper surface of a document table, a swing member having a base end pivotally attached to the base member so as to be vertically swingable, and overlapped on the upper surface side of the swing member. A lift member pivotally attached to the leading end of the member and capable of attaching a document pressure plate that covers the document table from above; and a lift member that is housed inside the rocking member in a state of being stretched outward in the longitudinal direction thereof, and A biasing member having a first cam portion on the proximal end for biasing the swing member upward and a second cam portion on the distal end for biasing the lift member in a direction overlapping the swing member. A downwardly extending hanging wall is formed at a tip end of the lift member, and a pressed portion with which a second cam portion of the urging member contacts is provided on the hanging wall. An opening and closing device for an original cover. 2. The apparatus according to claim 1, wherein the pressed portion is formed by bending the hanging wall itself. 3. The document pressing plate opening / closing device according to claim 2, wherein the pressed portion is formed by curving the lower end of the hanging wall inward in a curl shape. 4. A base member having a fixed base having an attachment plate for an upper surface of a document placing table, and a cam member having a lift cam surface fixed to the fixed base so as to be separable and contacting a first cam portion of an urging member. The document according to any one of claims 1 to 3, wherein a swing shaft for pivotally attaching the swing member is inserted through only the cam member without being inserted through the fixed base. Opening / closing device for crimping plate. 5. The base member includes a cam member having a lift cam surface with which a first cam portion of the urging member contacts,
5. The document cover opening / closing device according to claim 1, wherein the lift cam surface, the contact surface of the first cam portion, or both of them are subjected to fine unevenness having a function of retaining lubricating grease. 6. A grounding member having a spring force with one end fixed to one of the base member and the swinging member and the other end constantly sliding against the other. Opening / closing device for a document pressure bonding plate as described in (1).