JPH09183522A - Sheet cassette and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To press all the sizes of sheets against a reference face by appropriate pressing force by providing an energization adjusting means which is interlocked with movement of a regulating member, energizes sheets by a regulating member and an auxiliary regulating member in the case of receiving large-sized sheets, and releases sheet energization by the auxiliary regulating member in the case of receiving small-sized sheets. SOLUTION: Letter-sized sheets are stored in a sheet cassette B, and the rear ends and the side ends of the sheets are pressed so as to move a regulating member 15. A projecting part 17 is locked with a lock part 16a, so as to push out an auxiliary member 16 in the direction of going away from a reference face 10. Because the sheet regulating member 15 is fixed by a click under the condition of the auxiliary regulating member being pressed to a position not contacted with the sheets, energization force of the auxiliary regulating member 16 is not applied to the letter-sized sheets. When legal-sized sheets of the same width and longer length are received in the sheet cassette B and the regulating part is moved, the locking state of the projecting part 17 with the lock part 16a is released, and the sheets are pressed against the reference face 10 by energization force of plate springs of both regulating members 15, 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet cassette capable of accommodating sheets of a plurality of sizes and an image forming apparatus for mounting the sheet cassette to form an image.

[0002]

2. Description of the Related Art Today, image forming apparatuses such as copying machines and laser beam printers are widely used. In these apparatuses, a large number of sheets are stored in a cassette and the sheets are fed to form an image. However, in recent years, one in which a plurality of sizes of sheets can be appropriately stored by one type of cassette is used.

A conventional sheet cassette corresponding to a sheet size has a cassette body 50 and a sheet reference surface 51 serving as a conveyance reference when a sheet p is fed, as shown in FIGS. 10 and 11, for example. ing. Sheet p in cassette body 50
An intermediate plate 52 on which is mounted is rotatably attached, and a spring 53 is provided on the back side of the intermediate plate 52 to urge the intermediate plate 52 upward. A separation sheet 54 is attached on the middle plate 52 to prevent the lowermost sheet of the stacked sheets p from being double-fed. Also, the sheets p to be stacked on the middle plate 52
Separation claws 55 are provided for restricting the tip corners on the reference surface side and separating the sheets one by one during feeding.

A sheet regulating member 56 for regulating the rear end and the width direction of the sheet p is provided on the opposite side of the sheet reference surface 51 in the sheet conveying direction. This sheet regulating member 56 is used for an image of a printer or the like. It is possible to move along the slit 57 formed in the cassette body 50 so as to correspond to 5 types of sheets of B5 size, executive size, letter size, A4 size, and legal size that are frequently used in the forming device. There is. Further, a click portion (not shown) is provided at each position corresponding to each sheet size, and the regulation member 56 is fixed at the regulation position. The sheet size of each size is as follows.

B5 size → (width) 182 mm × (length) 257 mm, executive size → (width) 184.2 mm × (length) 266.7 mm, letter size → (width) 215.9 mm × (length) 279.4 mm A4 size → (width) 210 mm × (length) 297 mm, legal size → (width) 215.9 mm × (length) 355.6 mm.

The regulating member 56 regulates the rear end of the sheet by a wall-like regulating plate 58, and the side surface of the sheet p opposite to the sheet reference surface 51 is regulated by an elastic leaf spring member 59. Accordingly, the sheet p is moved by the spring member 59 to the reference surface 51.
It can be pressed tightly against.

Here, the legal size sheet is
Extremely long and heavy compared to other size sheets. It is preferable that the sheet p is pressed in the center in the lengthwise direction of the sheet or slightly forward of the center in the cassette,
The length difference between the shortest B5 size sheet and the longest legal size sheet is 173.6 mm. It is difficult for both types of sheet cassettes to hold near the center of the sheet. That is, when the restriction member 56 is set on a legal size sheet, the position of the spring member 59 to be pressed is considerably rearward from the center of the cassette.

Therefore, in order to balance the force for regulating the legal size sheet, an elastic auxiliary regulating member 60 is provided for pressing near the front side of the side surface on the anti-reference side of the sheet. This auxiliary regulation member 60 is
Only the widest letter size sheets and legal size sheets among the above 5 types are contacted. This gives
As shown in, the legal size sheet is
The force F1 generated by 59 and the force F2 generated by the auxiliary regulating member 60 ensure that the reference surface 51 is pressed.

[0009]

However, in the above structure, the auxiliary regulation member 60 is provided for the purpose of surely pressing the legal size sheet having a long length and a large mass against the sheet reference surface 51. As described above, the width size of the letter size sheet is the same as that of the legal size sheet.
When the sheet is moved, as shown in FIG.
The side surface of the sheet p is pressed by both the pressing force F1 by the pressing force F1 and the pressing force F2 by the auxiliary regulation member 60.

In order to stabilize the sheet conveyance, the sheets stored in the cassette should be the reference plane regardless of the size.
It is necessary to contact 51 with no gap, but if the force of pressing the sheet near the position facing the sheet reference surface 51 against the reference surface 51 is too strong, the frictional force between the side surface of the sheet and the reference surface 51 increases. As a result, the pressurization of the intermediate plate during feeding may be reduced, and the poor followability of the separation claw 55 to the intermediate plate 52 may cause defective feeding.

The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to press sheets of all sizes against a reference surface with an appropriate pressing force to enable reliable feeding. And to provide an image forming apparatus using the same.

[0012]

A typical structure according to the present invention for achieving the above object is to provide a sheet provided on one side in the sheet width direction of a cassette body in a sheet cassette capable of accommodating sheets of a plurality of sizes. A reference surface that is a conveyance reference, and a regulation member that is movable according to the size of a sheet to be stored, and that urges the sheet toward the reference surface, and the regulation member that separates the sheet from the reference surface. Auxiliary restricting member for urging the surface side, interlocking with the movement of the restricting member, when storing a large size sheet, the seat is biased by the restricting member and the auxiliary restricting member, and a small size sheet It is characterized by having an urging adjusting means for releasing the urging of the sheet by the auxiliary regulating member when the sheet is stored.

In the above structure, when a large size sheet is stored, the sheet is pressed against the sheet reference surface by receiving a biasing force from both the regulating member and the auxiliary member. However, when the small size sheet is stored, the force of pressing the sheet against the reference surface is received only by the regulating member. As a result, the sheet is pressed against the reference surface by an appropriate biasing force corresponding to the sheet size, and reliable feeding is performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the structure of a sheet cassette according to an embodiment of the present invention and an image forming apparatus using the same will be described with reference to the drawings.

[First Embodiment] A sheet cassette and an image forming apparatus according to a first embodiment will be described with reference to FIGS. 1 to 6. Incidentally, FIG. 1 is a structural explanatory view of an image forming apparatus in which a sheet cassette accommodating a small size sheet is mounted, FIG. 2 is a perspective explanatory view of the sheet cassette, and FIG. 3 is an image in which a sheet cassette accommodating a large size sheet is mounted. FIG. 4 is a perspective view of the sheet cassette, and FIG.
5 and 6 are configuration explanatory diagrams of the bias adjusting means when the small size sheet and the large size sheet are stored.

Here, as the order of description, the overall structure of the image forming apparatus will be described first, and then the structure of the sheet cassette will be described.

[Overall Structure of Image Forming Apparatus] As shown in FIGS. 1 and 3, the image forming apparatus (laser beam printer) A according to this embodiment forms a toner image by the image forming means and conveys it. The toner image is transferred and recorded on the recording sheet p conveyed by. That is, laser light based on image information from the optical system 1 is applied to the drum-shaped photosensitive drum 3 whose surface is uniformly charged by the primary charger 2 to form a latent image on the drum 3. The image is developed by the developing device 4 to form a toner image.

In synchronization with the formation of the toner image, the recording sheet p is conveyed from a sheet cassette B, which will be described later, by a conveying means 5 including a pickup roller 5a, a conveying roller pair 5b, a registration roller pair 5c, and the like, and the photosensitive drum. The toner image formed on No. 3 is transferred to the recording sheet p by applying a voltage to the transfer charger 6. Then, the recording sheet p after the image transfer is conveyed to a fixing roller pair 7 having a built-in heater to fix the transferred toner image on the recording sheet p.
Is conveyed by a pair of discharge rollers 5d and discharged to a discharge section (not shown).

Further, the toner remaining on the photosensitive drum 3 after the toner image is transferred to the recording sheet p is removed by the cleaning device 8.

<Structure of Sheet Cassette> A mounting means for the sheet cassette B is provided at the bottom of the image forming apparatus A so that the sheet cassette B can be attached and detached. This sheet cassette B is a universal cassette corresponding to several sizes, and as shown in FIGS. 1 and 2, a sheet reference surface 10 serving as a feeding reference when feeding a sheet p to the cassette body 9. It is provided. An intermediate plate 11 on which sheets p are stacked is rotatably attached to the cassette body 9, and the intermediate plate 11 is urged upward by a pressing spring 12 from the back side. A separation sheet 13 is attached to a predetermined position on the front surface of the middle plate 11 to prevent the lowermost sheet p of the stack of sheets p stacked on the middle plate 11 from being fed in a double feed. Further, on the downstream side of the cassette body 9 in the sheet feeding direction, a tip corner portion on the reference surface side of the sheets p stacked on the intermediate plate 11 is regulated to separate the sheets p one by one during feeding. A separating claw 14 is provided.

On the other hand, on the opposite side of the sheet reference surface 10 (opposite side of the sheet width direction), a sheet regulating member 15 for regulating the rear end of the sheet p and the width direction is attached near the rear of the sheet feeding direction. The sheet regulating member 15 is movable along the slit 9a formed in the cassette body 9 so as to correspond to the above-mentioned five types of sheets of B5 size, executive size, letter size, A4 size, and legal size. Further, a click portion (not shown) is provided at each position, and the regulation member 15 is fixed at the regulation position according to each size. 1 and 2 show the state in which the sheet regulating member 15 is fixed at the letter size position, and FIGS. 3 and 4 show the state in which it is fixed at the legal size position.

The sheet regulating member 15 according to this embodiment includes a wall-shaped regulating plate 15a for regulating the rear end of the sheet and the reference surface 10 described above.
And a leaf spring member 15b having elasticity for restricting the end portion in the sheet width direction on the opposite side.

Here, as described above, the legal size is 173.6 as compared with the shortest B5 size sheet.
mm is also long, and the position pressed by the sheet regulating member 15 is behind the center of the sheet in the length direction. For this reason, an auxiliary restricting member 16 made of a leaf spring member having elasticity for pressing the front side opposite to the reference surface 10 in the seat width direction is provided. As a result, in the case of a legal size sheet having a long length and a heavy mass, as shown in FIG.
Biasing force F1 of the two leaf spring members 15 and 15 and the auxiliary regulation member 16,
It is pressed firmly against the sheet reference surface 10 by F2.

The sheet regulating member 15 is provided with a bias adjusting means. This urging adjusting means is for changing the urging force applied to the reference surface 10 depending on whether the sheet size is large or small. As shown in FIG. 5 and FIG. 6, the structure is such that a protrusion 17 is provided at the end of the sheet regulation member 15, and a locking portion 16a is formed at the end of the auxiliary regulation member 16 facing this. There is. Therefore, when the sheet restricting member 15 is moved toward the auxiliary restricting member 16, as shown in FIG. 5, the locking portion 16a goes under the protrusion 17, and the auxiliary restricting member 16 biases the leaf spring ( F2) is regulated. On the other hand, when the sheet restricting member 15 is moved in the direction away from the auxiliary restricting member 16 contrary to the above, the protrusion 17 and the engaging portion 16a
And the biasing force of the auxiliary regulation member 16 is applied to the stored sheet p.

Therefore, when the letter size sheet p is stored in the sheet cassette B and the sheet regulating member 15 is moved so as to press the rear end and the side end of the sheet, FIGS.
Further, as shown in FIG. 5, the projection 17 is locked to the locking portion 16a, and the auxiliary regulation member 16 is pushed away from the reference surface 10 and pushed to a position where the auxiliary regulation member 16 does not contact the letter size sheet. In this state, the sheet regulating member 15 is fixed by the click portion. In this state, only the urging force F1 by the leaf spring portion 15b of the sheet restricting member 15 is applied to the sheet p, and the urging force F2 of the auxiliary restricting member 16 which is unnecessary for a small size letter size sheet is not applied.

Further, a legal size sheet p having the same width and a longer length as compared with the letter size is stored in the sheet cassette B, and the sheet regulating member 15 is moved so as to press the rear end and the side end of the sheet. Then, as shown in FIGS. 3, 4 and 6, the engagement state between the protrusion 17 and the engagement portion 16a is released, so that the side end of the legal-size sheet has the sheet regulation member 15 and the auxiliary regulation member. Energizing force F of 16 leaf springs
The large legal size sheet is urged by 1 and F2 and is pressed against the reference surface 10 by an appropriate urging force.

Therefore, the sheet is pressed against the reference surface 10 with an appropriate urging force corresponding to the sheet size, and the defective feeding rate of the sheet p in the sheet cassette B is reduced and the sheet feeding system is improved. To be

The bias adjusting means has the same effect when feeding sheets having the same width but different lengths, such as A3 size and A4 lateral size, A4 size and A5 lateral size, and the like. You can

[Second Embodiment] Next, a second embodiment of the sheet cassette will be described with reference to FIGS. 7 to 9. The same members as those in the first embodiment described above are designated by the same reference numerals, and duplicate description will be omitted.

In this sheet cassette, a member for regulating the rear end of the sheet and a member for regulating the side end are constituted by different members, and the sheet p is placed at a position facing the sheet reference surface 10 of the cassette body 9. A width regulating member 18 for regulating the width direction is provided, and a rear end regulating member 19 for regulating the rear end of the sheet is provided near the rear of the sheet feeding direction. This width regulation member 18
The rear end regulating member 19 can be moved along the slits 20a and 20b formed in the cassette body 9, and the spring member 21 functions to press the sheet p against the sheet reference surface 10. The width regulating member 18 and the rear end regulating member 19 are the sheet regulating member 15 in the first embodiment described above.
It has the same function as, and can be moved independently corresponding to five types of sheets of B5 size, executive size, letter size, A4 size, and legal size. Further, each position has a click portion (not shown), and the regulating member is provided at a prescribed position.
18 and 19 can be fixed.

An auxiliary regulating member 22 having an elastic member (a leaf spring member in this embodiment) is attached to the rear side of the cassette on the side opposite to the reference surface 10 of the cassette body 9 in the sheet width direction, and the center of rotation 23a. An auxiliary spring holder 23 that is rotatable around is attached.

As shown in FIG. 8, when the trailing edge regulating member 19 is set at the letter size sheet position, the spring holder 23 is stopped at a position where the auxiliary regulating member 22 does not contact the sheet by an elastic member (not shown). Is set to. In this state, only the urging force F1 of the spring member 21 on the width regulating member 18 is applied to the sheet p, and the urging force F2 of the auxiliary regulating member 22 unnecessary for the letter size sheet is not applied.

On the other hand, when the rear end regulating member 19 is set at the position of the legal size sheet, the protrusion 19a provided on the rear end regulating member 19 is formed on the spring holder 23 as shown in FIG. The protrusion 23b is pushed in and fixed by a click portion (not shown). In this state, the auxiliary restricting member 22 protrudes toward the sheet reference surface 10 by a specified amount and urges the side surface of the legal size sheet with the force of F2. Therefore, in the legal size sheet, the side surface is pressed against the sheet reference surface 10 by the biasing force of F1 + F2 by the spring members of the width restricting member 18 and the auxiliary restricting member 22.

Therefore, even in the sheet cassette according to the second embodiment, it is possible to obtain an appropriate lateral pressure force corresponding to all sheet sizes, reduce the feeding failure rate, and improve the sheet feeding system. Can bring.

[Other Embodiments] In the above-described embodiments, the laser beam printer is illustrated as the image forming apparatus, but the image forming apparatus using the sheet cassette is not limited to this, and may be used in a copying machine, a facsimile machine, or the like. The same can be applied to other image forming apparatuses.

Further, in the above-described embodiment, the sheet cassette for storing the recording sheets to be supplied to the image forming apparatus is exemplified, but this sheet cassette is not only for storing the recording sheets but also for storing the originals and reading them. It can also be used in the same manner when it is mounted on a reader for supplying the means.

[0037]

As described above, according to the present invention, since the urging force to the reference surface is changed corresponding to the large size sheet and the small size sheet, the sheet is always referenced by the appropriate urging force regardless of the sheet size. It is possible to improve the sheet conveyance system by pressing it against the surface and avoiding feeding failure and conveyance failure.

Further, if the regulating member that moves in accordance with the sheet size is constituted by an integral member, the urging force can be adjusted by moving only one member, and the operability can be improved. I can. On the other hand, if the regulation member is configured to regulate the widthwise direction of the sheet from the rear end of the sheet, the degree of freedom in adjusting the biasing force can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram of an image forming apparatus in which a sheet cassette storing small size sheets is mounted.

FIG. 2 is a perspective explanatory view of a sheet cassette in which a regulation member is moved corresponding to a small size sheet.

FIG. 3 is a configuration explanatory diagram of an image forming apparatus in which a sheet cassette that accommodates large-sized sheets is mounted.

FIG. 4 is a perspective explanatory view of a sheet cassette in which a regulation member is moved corresponding to a large size sheet.

FIG. 5 is a structural explanatory view of a bias adjusting means when a small size sheet is stored.

FIG. 6 is a structural explanatory view of a bias adjusting means when a large size sheet is stored.

FIG. 7 is a perspective explanatory view of a sheet cassette according to a second embodiment.

FIG. 8 is a structural explanatory view of a bias adjusting means when a large size sheet is stored in the sheet cassette according to the second exemplary embodiment.

FIG. 9 is a structural explanatory view of a bias adjusting means when a small size sheet is stored in the sheet cassette according to the second exemplary embodiment.

FIG. 10 is a partial configuration explanatory diagram of an image forming apparatus in which a sheet cassette according to a conventional technique is mounted.

FIG. 11 is a perspective explanatory view of a sheet cassette according to a conventional technique.

FIG. 12 is a structural explanatory view for urging a sheet when a large-sized sheet is stored in the sheet cassette according to the related art to the reference surface.

FIG. 13 is a configuration explanatory view for urging a sheet when a small-sized sheet is stored in the sheet cassette according to the related art to the reference surface.

[Explanation of symbols]

 A ... Image forming apparatus B ... Sheet cassette 1 ... Optical system 2 ... Primary charger 3 ... Photosensitive drum 4 ... Developing device 5 ... Conveying means 5a ... Pickup roller 5b ... Conveying roller pair 5c ... Registration roller pair 5d ... Ejection roller pair 6 ... Transfer charging device 7 ... Fixing roller pair 8 ... Cleaning device 9 ... Cassette body 10 ... Sheet reference surface 11 ... Middle plate 12 ... Pressing spring 13 ... Separation sheet 14 ... Separation claw 15 ... Sheet regulation member 15a ... Regulation plate 15b ... Leaf spring member 16 ... Auxiliary regulating member 16a ... Locking portion 17 ... Protrusion 18 ... Width regulating member 19 ... Rear edge regulating member 19a ... Protrusions 20a, 20b ... Slit 21 ... Spring member 22 ... Auxiliary regulating member 23 ... Spring holder 23a ... Center of rotation 23b ... Projection

Claims (5)

[Claims] 1. In a sheet cassette capable of accommodating sheets of a plurality of sizes, it is movable in correspondence with a reference surface provided on one side of the cassette body in the sheet width direction and serving as a sheet conveyance reference, and the size of the sheet to be accommodated. Yes, a regulating member for urging the sheet toward the reference surface side, an auxiliary regulating member for urging the sheet toward the reference surface side separately from the regulating member, and interlocking with the movement of the regulating member. Urging adjusting means for urging the sheet by the regulation member and the auxiliary regulation member when storing a large size sheet, and releasing the sheet urging by the auxiliary regulation member when accommodating a small size sheet And a sheet cassette. 2. The sheet cassette according to claim 1, wherein the large size sheet and the small size sheet have the same width and different lengths in the transport direction. 3. The sheet cassette according to claim 1, wherein the regulating member is a member that integrally regulates a sheet width direction and a sheet lengthwise rear end. 4. The sheet cassette according to claim 1, wherein the regulation member performs regulation in the width direction of the sheet and regulation in the rear end in the length direction by separate members. 5. An image forming apparatus for conveying a sheet stored in a sheet cassette to form an image, a cassette mounting means for mounting the sheet cassette according to claim 1. An image forming apparatus, comprising: a conveyance unit configured to convey a sheet in the sheet cassette; and an image forming unit configured to form an image on the conveyed sheet.