JPH0467028A - image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is an image forming apparatus with a movable document table, that is, a document table on which a document is set is moved to a document scanning section such as a document illumination section and an image reading section of the main body of the device. A copying machine that drives the (main scanning unit) to reciprocate (sub-scanning movement) and performs image formation or image reading during the forward movement process or backward movement process.
The present invention relates to image forming devices such as image reading devices and image display devices.

(Prior Art) The document table moving type apparatus configuration as described above is often employed in small-sized copying machines and the like.

Generally, a document table, mainly made of a transparent plate (manuscript table glass) such as a glass plate, is placed on the top surface of the device body where the document scanning section is located, and is placed between the front side and the back side of the document table. It is installed so that it can be horizontally reciprocated in the left-right direction of the apparatus main body using the provided parallel rail members, and the set original is scanned by driving the original table to reciprocate by the length of the original using a rack gear and a pinion gear. The document table moves back and forth once for each copy (or one reading).

The rack gear should be mounted on the document table side with its long side facing left and right and the teeth facing downward, and a forward and reverse drive controlled forward and reverse gear provided on the main body of the apparatus should be engaged with the rack gear with the teeth facing downward. The forward and reverse driving forces of the anion gear are applied to the rack gear to drive the document table to reciprocate.

As described above, the height position (interval distance) of the glass surface of the document table (original placement surface) of the document table that is driven to move back and forth with respect to the document scanning section on the device main body side is optically determined to a predetermined height position. Therefore, the front side and the lower surface of the near side of the document table glass are received by the front rail and the height adjustment frame placed at the far end of the document scanning section, respectively. A structure is adopted that defines the height position.

(Problems to be Solved by the Invention) In such an image forming apparatus with a movable document table, when the document table moves back and forth, the document table protrudes greatly outward from the left end side or the right end side, and the document table 5 The center of gravity of the device moves significantly toward the left or right end of the device body.

Therefore, when the document table moves forward or forward, a moment acts on the document table in the direction that the part of the device main body that corresponds to the document scanning section moves away from the document scanning section, and the actual In addition, the lower surface of the platen glass rises up from the height adjustment frame without contacting it, causing deviation in the optically prescribed height position of the platen glass relative to the document scanning section, which may cause problems in output images and scanned images. Occasionally, there were areas that were out of focus or out of focus.

Therefore, by increasing the accuracy of the height adjustment frame and front rail installation, it is necessary to minimize the above-mentioned lifting of the platen glass and make adjustments to prevent the front part of the image and the out-of-focus part from occurring. However, it was a difficult task that required delicate adjustment, time, and skill.

In addition, the rack gear and pinion gear that drive the document table to reciprocate are mounted on the document table side with the tooth surface facing downward, and the rack gear on the apparatus main body side with the tooth surface facing downward, as described above. The two gears are meshed to transmit the forward and reverse driving force of the two gears to the rack gear to move the document table back and forth, so when the drive force is transmitted to the rack gear by the pinion gear,
The rack gear, that is, the document table, has a gear pressure angle θ (usually 20°).
) is applied upward by COS θ, and this is also a factor that causes the predetermined height position of the document table glass relative to the document scanning section to fluctuate and become unstable.

The present invention is an image forming apparatus that similarly uses a rack to move the document table back and forth, but it solves the above problems and allows the document glass to be moved from a predetermined height position relative to the document scanning section. It is an object of the present invention to provide an image that prevents the occurrence of pre-distance and skewed parts of output images and read images caused by fluctuations in uplift.

(Means for Solving the Problems) The present invention is an image forming apparatus characterized by the following configuration.

(In an image forming apparatus that scans a document by driving a rack provided on the document table and reciprocating the document table with respect to the main body of the device, the rack is formed in a helical gear.
At least during the movement of the document table during the document scanning process, the thrust force of the helical gear is configured to act in a direction to prevent the document table from floating away from a predetermined height position of the document scanning section. Features of the image forming device.

(2) The document table is provided with two racks for forward drive and backward drive, and at least the rack on the side that moves the document table during the document scanning process is formed into a helical bar, and the thrust force of the helical bulk gear is The image forming apparatus according to (1) above, which operates as described above.

(Function) By using a helical gear as the rack installed on the document table, the rack driving force acting on the hasp gear is divided into a propulsive force component of the rack, that is, the document table, and a thrust force in a direction perpendicular to the propulsive force component. .

Therefore, the present invention utilizes the thrust force, and at least during the movement of the document table 6 during the document scanning process, the thrust force is directed in a direction that prevents the document table from floating away from a predetermined height position of the document scanning section. It is structured in a relationship that affects
As a result, with a simple configuration, it is possible to effectively prevent the occurrence of blurred or out-of-focus areas in output images or read images caused by the phenomenon of the document table floating away from a predetermined position relative to the document scanning unit. Ta.

(Embodiments) <Embodiment 1> FIG. 1 is a schematic cross-sectional view of an image forming apparatus (electrophotographic copying machine) according to an embodiment of the present invention.

1 is a general code of the copying machine, 2 and 3 are the lower machine case (bottom plate) of the copy machine, and the upper machine case (cover) which is enclosed in the lower machine case 2. The front of the copying machine 1 is on the left side wall in the drawing. The upper machine casing 3 is opened and raised from the lower machine casing 2 around a hinge (not shown) to greatly open the interior of the copying machine, so that the process cartridge 4 can be attached and removed, and the interior of the copying machine can be maintained and inspected. However, since this configuration is outside the main point, the details will be omitted.

6 is a frame provided inside the upper machine case 3 and integrally with the upper machine case;
The process cartridge 4 is removably set in a predetermined storage section provided in the frame.

The process cartridge 4 includes an electrophotographic photosensitive drum 5 and predetermined image forming process equipment such as a developing device and a cleaning device, but only the photosensitive drum 5 is shown in the figure and the others are omitted.

Reference numeral 7 denotes a short focus lens array that is attached to and supported by the frame 6 at the L portion of the process cartridge 4 mounted on the frame 6. The long axis of the short focus lens array 7 and the frame 6
The photosensitive tram 5 inside the process cartridge 4 installed in the
The central axes of the short focus lens array 7 and the surface of the photosensitive drum 5 are set at a predetermined constant distance along the length of the short focus lens array.

Reference numeral 12 denotes a document frame (rack frame (large)).
Accuride rail 11 arranged in the direction perpendicular to the page
The copying machine body 3 is attached to the copying machine body 3 and can be reciprocated horizontally in the left-right direction of the copying machine body on the upper surface of the F machine housing 3 on the immediate side. The inner member of the Accuride rail 11 is fixed to a support leg (not shown) provided on the lower machine casing, and the outer member is fixed to the back surface of the original frame 12.

Reference numeral 10 denotes a front rail having a U-shaped cross section and fixed to the upper surface of the front side of the frame 6 and disposed in the left-right direction of the main body of the copying machine.

Reference numeral 8 denotes a document table crow, whose immediate side is fixed to the document table frame 12, and whose hand side is inserted into the horizontal groove of the front rail 10 having a U-shaped cross section to be received. be.

Therefore, the document table frame 12 and the document table crow 8 are integrally guided by the Accuride rail 11 and the front rail 10 and can freely reciprocate on the upper machine casing 3 in the left-right direction of the copying machine body. The lower surface of the front side of the document table glass 8 is supported by the bottom surface in the horizontal groove 10 of the front rail and slides on the bottom surface.

Reference numeral 9 denotes a height adjustment piece, which is fixed at a position near the rear end of the short focus lens array 7 on the upper surface of the frame 6 on the near side. The lower surface of the document table glass 8 on the near side is received on the upper surface, and the top 9 and the front rail 10 reduce the height of the document table glass surface (original placement surface) relative to the document scanning section (short focus lens array 7 section). Regulations are made. That is, the distance between the document table glass 8 and the short focus lens array 7 is defined as a predetermined constant distance along the length of the lens array.

Reference numeral 13 designates a hanging member (rack stand (small)) for mounting a rack gear, which is integrally fixed to the back surface of the document stand frame 12 and is attached with its longitudinal direction in the left-right direction of the copying machine main body. The rack gear 14 is installed and supported on the rear side, with the tooth surface facing sideways toward the rear wall of the copying machine, and with the length extending in the left-right direction of the copying machine main body.

Reference numeral 15 is a nonion gear meshed with the rack gear 14. Reference numeral 16 denotes a drive device for controlling the forward and reverse rotation of the onion gear, and includes a well-known spring clutch mechanism and the like.

Reference numeral 18 denotes a document pressure bonding plate, whose base 18a on the immediate side is fixedly attached to the top surface of the document frame 12, and is rotatable about a thin hinge portion 18b, so that the top surface of the document glass 8 It can be rotated to open and close. Reference numeral 17 denotes a white sheet (white sheet) attached to the back surface of this original pressure bonding plate 18.

For the original N4 (not shown), open and raise the original pressing plate 18 from above the original platen glass 8, place the original on the upper surface of the original platen glass 8 with the image surface facing downward according to a predetermined placement standard, and press the original on top of it. It is set by closing and pressing the plate 18.

The document table 20, which consists of the document table frame 12, document table glass 8, document pressure bonding plate 18, etc., is normally on standby at a state position within the upper surface area of the copying machine main body 1, as shown by the solid line in FIG. 3, as its home position. are doing.

(2) When the inion gear 15 is driven in reverse based on the copy start signal, the rack gear 14 receives a force of movement to the left of the copying machine, and the document table 20 is moved from the home position to the left of the copying machine main body 1. Driven to move. This movement of the document table 20 to the left side is referred to as backward movement.

As the document table 20 moves backward, the left end side of the document table protrudes outward from the left end of the copying machine main body 1. When the document table 20 reaches the backward movement end position indicated by the two-dot chain line in FIG.
Then, the reverse rotation of the onion gear 15 is stopped, and the backward movement of the document table 20 is stopped.

01 Then, the onion gear 15 is switched to forward rotation drive, and the rack gear 14 receives the rightward movement force of the copying machine main body 1, so that the document table 20 moves from the above-mentioned backward movement end point position to the forward movement start position and moves the copying machine main body 1 It moves forward at a predetermined speed to the right side a.

In this embodiment, this forward movement process of the document table 20 is referred to as a document scanning process.

That is, simultaneously with the start of the forward movement a of the document table 20, an unillustrated document illumination lamp disposed near the short focus lens array 7 is turned on, and the document table 20, which has moved forward a, scans the document in the copying machine main body. In the process of passing above the short-focus lens array 7, which is a The light reflected from the document surface of the illumination light enters the short focal length lens array 7 and is sequentially image-formed and exposed on the rotationally driven photosensitive drum 5 surface.
Image formation is executed in cooperation with other image forming process equipment (not shown), and an image formed product (copy) is output.

(2) As the forward motion a progresses, the right end of the document table 20 protrudes outward from the right end of the copying machine main body 1.

When the document table 20 reaches the predetermined forward end position indicated by the three-dot chain in FIG. By being switched, the document table 20 moves backward, and when the document table 20 returns to the home position shown in FIG.
It is in a standby state until the next copy start signal is input.

During continuous copying of multiple sheets, the document table 20 does not stop at the home position, but moves backward, but continues to move forward again from the backward end position indicated by the two-dot chain line in FIG. 3. The settings are repeated several times for each copy, and when the scan process for the final copy of the original is completed, it is returned to the home position and enters a standby state.

The rack gear 14 has a twist of θ1 and 5 as shown in FIG.
It is a helical gear on the left side in the helix direction, and the binion gear 15 has a helix angle θ1 and is a helical gear on the left side in the torsional direction.

When the gear 15 is rotated forward in the six directions of arrows (counterclockwise on the plane), the rack gear 14, that is, the document table 20
move forward in the direction. In this forward movement process, the driving force F acting on the rack gear 14 from the biogear 15 is F2 and F2.
, F2 acts as a driving force for the forward movement of the rack gear 14, that is, the document table 2o, and F pulls down the rack gear 14, that is, the document table 20, to raise the lower surface of the document table glass 8 and actively move it toward the top 9. It acts as a thrust force.

Therefore, as mentioned above, in FIG. 3, the document table 20 is
In the process of moving forward a from the forward start point position shown by the two-dot chain line to the forward end point position shown by the three-dot chain line, the rotation moment ml''m2 acting on the document table 20 due to the movement of the center of gravity of the document table causes the rotation moment ml''m2 to move in the document scanning unit 7. The above thrust force F may cause the document platen crow 8 to float away from the height adjustment frame 9.
, and is blocked by the document table 20 in the document scanning process.
In the forward movement process a, the document scanning unit 7 is always stably maintained at the optical height position of the document table glass 8 surface or at a predetermined height position, and image formation without image blur or out-of-focus is performed. .

On the other hand, in the process in which the double-on gear 15 is reversely driven in the direction B (FIG. 2) and the rack gear 14, that is, the document table 2o moves backward in the direction b, the thrust force F acts in the opposite direction. In the document scanning unit 7, the moment m1 ・m that acts on the document table glass 8 surface and the document table 20
Although the action of actively pressing the document platen 20 against the height-setting frame 9 to prevent it from floating apart does not work, the document platen 20
Since the backward movement process is not a document scanning process, there is no functional problem even if the document table glass 8 is lifted off from the height adjustment frame 9.

It is advantageous to ensure that the thrust force caused by the twisting of the helical gear has a sufficient margin than the lifting force from the height-setting frame 9 of the document table glass 8 due to the movement of the center of gravity of the document table 20 in order to prevent image blur. It goes without saying that.

<Embodiment 2> This embodiment (FIGS. 4 and 5) includes a first busbar gear for driving the forward movement of the document table 2o, a first throat onion gear meshing therewith, and a second busbar gear for driving the document table 2o to move backward. By having two sets of second throats that mesh with the two sets and using them separately, the document table 20 is always pulled downward during both the forward movement process a and the backward movement process of the document table 2o. By applying a thrust force to raise the lower surface of the document table glass 8 and actively press it against the frame 9, the optical height position of the document table glass 8 surface in the document scanning section 7 is stabilized at a predetermined height position. It was designed to be maintained.

Components and portions that are the same as those in Example 1 are given the same reference numerals and repeated explanations will be omitted.

The first hash bar gear 13 for driving the forward movement of the document table 20 is placed horizontally on the rear side of the hanging member 13 integral with the document table frame 12 with the tooth surface facing toward the rear wall of the copying machine, as in the first embodiment. It is mounted and supported with its long side pointing in the left-right direction of the copying machine main body.

The second hash bar gear 53 for driving the backward movement of the document table 20 is connected to the downwardly bent plate portion 1 on the rear side of the document table frame 12.
The gear 2a is mounted and supported in parallel with the first helical bulk gear 13 with its tooth surface on the back side facing the inside of the copying machine, with its long side facing in the left-right direction of the copying machine main body.

59 is a vertical drive shaft rotationally driven by the drive device 16;
The upper end portion is supported by a bearing 58, and the bearing 58 is fixed to the back surface of the upper machine casing 3 with a support plate 62.

Reference numerals 54 and 56 designate first and second sun gears that are disposed concentrically above and below the vertical drive shaft 59.

The upper first sun gear 54 is fixed to a vertical drive shaft 59 and is driven to rotate integrally with the shaft 59.

The lower second sun gear 56 is loosely fitted around the vertical drive shaft 59, and is rotated around the shaft 59 by receiving torque from the drive device 16 separately from the shaft 59.

Reference numeral 60 encloses the upper first sun gear 54 and freely rotates around the vertical drive shaft 59 via bearings 55 and 56.
9 is a swinging bracket with a simplified U-shape in the transverse direction.

61 is a vertical drive shaft 5 on the tip side of this swing bracket 60.
9 is a vertical axis that is supported, and this vertical axis 61
On the other hand, the first helical bulk gear 15 is loosely fitted inside the rocking blanket 60 and meshed with the first sun gear 54.

Further, a second helical helical inion gear 57 is loosely fitted and supported on the downwardly extending shaft portion of the rocking blanket of the vertical shaft 61, and the second helical helical inion gear 57 is meshed with the second sun gear 56. be. This second hashband on gear 5
A friction member 62 is interposed between the upper end surface of the swing blanket 7 and the lower surface of the swinging blanket 60.

The vertical drive shaft 59, that is, the first sun gear 54 is rotationally driven in the clockwise direction C (FIG. 5(b)) when viewed from above, and the second sun gear 56 is also rotated around the vertical drive shaft 59, which is different from the shaft 59. Similarly, when viewed from the plane, the torque transmitting means is clockwise C (see Fig. 5).
a) (C)).

The first and second helical ring gears 15 and 57 are brought into rotation in conjunction with the rotational drive of the first and second sun gears 54 and 56, respectively.

During this driving, a force is applied to the swinging bracket 60 to rotate in a clockwise direction when viewed from the plane, about the vertical drive shaft 59 due to the frictional force between the friction member 62 and the second Haspa donion gear 57. f acts.

■、j! When the manuscript table 20 is waiting at the home position of the solid line water position shown in FIG. They are in a rotating angle position where they are facing and meshing. The first helical ring gear 15 is separated from the first helical ring gear 14 and has a cut edge.

(2) Rotation of the vertical drive shaft 59, that is, the first sun gear 54 and the second sun gear 56, is started based on the copy start signal.

In conjunction with the rotational drive of the second sun gear 56, the second helical gear 57 is rotationally driven, and the second helical gear 53 in mesh with the second helical gear 57 is given a propulsive force in the backward direction of the document table. As a result, the document table 20 is driven to move backward.

In this case, the torsion direction and twist angle of the teeth of the second hash gear 57 and the second hash gear 53 are such that when the document table 20 is pulled down in the backward movement stroke of the document table 20, the document table glass 8 is The relationship is such that a thrust force acts to raise the height of the lower surface and actively press it against the piece 9.

Note that the first helical ring gear 15 is kept in an idle state.

(2) When the backward movement of the FA manuscript table 20 advances and reaches the end point of the backward movement at the two-dot chain line water position shown in FIG. The gears 53 and 57 are disengaged (double-dashed line in FIG. 5(b)).

Then, the swinging blanket 60 automatically rotates approximately 180 degrees about the shaft 59 due to the clockwise rotation biasing force f described above, and the first and second throat onion gears 15 and 53 respectively rotate. It revolves around the second sun gears 54 and 56, and the first helical assembly gear 15 faces and meshes with the first helical assembly gear 14, as shown by the solid line in FIG. 5(b).

As a result, a propulsive force in the forward direction a of the original platen acts on the first hash bar gear 14, and the original platen 20 is driven to move forward (
(original scanning process).

In this case, the helical direction and helical angle of the teeth of the first helical bulk gear 15 and the first helical bulk gear 14 are in the same relationship as the gears 14 and 15 of the first embodiment (FIG. 2). Even in the forward movement process of the document table 20, the document table 2
A thrust force is applied which pulls down the document table glass 8 to raise the height of the lower surface of the document table glass 8 and actively presses it against the frame 9.

Note that the second hashedron gear 57 is kept in an idling state.

(3) As the forward movement a of the document table 20 progresses to 3 in FIG.
When it reaches the end point of the forward movement indicated by the dotted chain line, it passes the left end 14a of the first helical bulk gear 14 or the position of the first helical bulk gear 15, and the meshing of both gears 14 and 15 is disengaged (Fig. 5 (C)). (shown by the two-dot chain line).

Then, the swinging blanket 60 automatically rotates approximately 180 degrees again about the shaft 59 by the aforementioned clockwise rotation urging force f, and the first and second throat onion gears 15 and 53 respectively move to the first position. Then, it revolves around the second sun gears 54 and 56, and as shown by the solid line in FIG. Then, the document table 20 is driven backward again.

Thus, in this embodiment, in both the forward movement process a and the backward movement process of the document table 20, a thrust force acts to raise the lower surface of the document table glass 8 and actively press it against the frame 9. The optical height position of the surface is always stably maintained at a predetermined height position.

In this embodiment, since the backward moving process of the document table 20 is a non-scanning process of the document, the second rack gear 53 for driving the document table out-of-the-way movement and the second rack gear 57 that meshes with it are You don't have to force it into a hashbag gear.

(Effects of the Invention) As described above, according to the present invention, the original platen (original platen glass)
It is possible to effectively prevent the occurrence of a pressure image or a predetermined portion or an out-of-focus portion of a read image due to a floating phenomenon from a predetermined height position with respect to the document scanning unit of the document scanning unit. The intended purpose is well achieved.

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[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment. Fig. 2 is an explanatory diagram of component forces in Hasha gear. FIG. 3 is an explanatory diagram of the reciprocating movement of the document table and the rotation moment of the document table. FIG. 4 is a schematic cross-sectional view of the main parts of the image forming apparatus of the second embodiment. FIGS. 5(a), 5(b), and 5(c) are explanatory views of the operation of the swing bracket with respect to the first and second rack gears. 1 is a general code of the image forming apparatus, 20 is a general code of the reciprocating document table, 7 is a short focus lens array (document scanning section),
12 is a document table frame, 8 is a document table crow, 9 is a height adjustment piece, 14 is a lot rack gear (first rack gear), 15
is the Hasuba pinion gear (first gear), 53 is the second rack gear, and 57 is the second gear. Patent applicant: Canon Co., Ltd. Kaya 5 ((1')

Claims (2)

[Claims] (1) In an image forming apparatus that scans a document by driving a rack provided on the document table and reciprocating the document table with respect to the main body of the device, the rack is formed as a helical gear, and the document is scanned at least during the document scanning process. An image forming apparatus characterized in that, while the table is moving, a thrust force of the helical gear acts in a direction to prevent the document table from floating away from a predetermined height position of the document scanning section. (2) The document table is provided with two racks for forward drive and backward drive, and at least the rack on the side that moves the document table during the document scanning process is formed into a helical bar, and the thrust of the helical rack gear The force acts as described above,
The image forming apparatus according to claim 1, characterized in that: