JP2551765Y2 - Open / close buffer mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus in which a lower body and an upper body are hingedly connected to each other around a fulcrum, such as an image forming apparatus. Regarding the opening / closing buffer mechanism of the first component and the second component, in particular, an image carrier and a print head that outputs a signal corresponding to image information on the image carrier are configured to be able to freely contact and separate at an opposing portion. The present invention relates to an opening / closing buffer mechanism applied to an image forming apparatus.

[Conventional technology and its problems]

2. Description of the Related Art As a conventional opening / closing buffer mechanism, for example, in an image forming apparatus, an upper body and a lower body are connected by a hinge structure, and the upper body is opened during maintenance such as paper jam processing or toner (developer) replenishment. There is something. This type of image forming apparatus is called a shell open type because it has a structure like a bivalve, and occupies most of the image forming apparatuses.

Such a type includes a print head that irradiates image information, for example, as image light to a photosensitive drum as an image carrier, and a member that forms an electrostatic latent image by receiving the irradiation. A photosensitive drum formed on the surface is provided separately for the upper and lower bodies, and is often configured to be able to freely contact and separate at an opposing portion. In this case, generally, the print head is provided on the upper body side, and the photosensitive drum and other peripheral members of the photosensitive drum are provided on the lower body side, but of course, the arrangement is reversed. In some cases, both are arranged on one side of the fuselage. For example, in the case where a print head and a photosensitive drum are arranged on one machine side, a photosensitive drum and peripheral members for image formation are further integrated into a process kit, and the process kit is removed from the machine body to remove the two. It is configured to be freely contactable and detachable.

The print head and the photosensitive drum are commonly moved into and out of contact with each other through the above-described variations of the image forming apparatus. The distance between the print head and the photosensitive drum is determined by the depth of focus of the print head. Although it can not be said unconditionally in relation, it is a part that must be relatively severely suppressed, if an error occurs in the distance of this photoreceptor, the sharpness of the outline and lines of the image will be deteriorated, and so-called sweet images will be produced. turn into.

As described above, in the image forming apparatus of the type in which the print head and the photosensitive drum are separated from and separated from each other, it is naturally unavoidable in structure that the dimensional accuracy of the distance tends to be lower than that in the case where both are fixed. However, there has been proposed one having the above-described structure in which the distance between the print head and the photosensitive drum is maintained at a constant value.

However, this proposal still suffers under certain conditions, and the image may lack sharpness.

For example, in the above-described shell open type image forming apparatus, when the upper body is closed from the open state, the lower body is shocked by vigorously closing the upper body, and a photosensitive drum (described later) is damaged. there were. In order to explain such a problem, a shell-open type image forming apparatus will be described with reference to FIG. 2, and then the upper body, which is a problem of the conventional opening / closing buffer mechanism, will be rapidly reduced with reference to FIGS. An example of an inconvenience that occurs when the user closes the window will be described.

First, in FIG. 2, reference numeral 1 denotes an image forming apparatus in which an upper body 3 is connected to a lower body 2 by a hinge 4 so as to be freely opened and closed.

In the lower body 2, 5 is a photosensitive drum 6 rotating in the direction of the arrow, a cleaner 7 for cleaning the peripheral surface of the photosensitive drum 6,
A charger 8 for charging the peripheral surface of the photosensitive drum 6 with a potential having a uniform polarity, and attaching toner (developer) to an electrostatic latent image formed on the peripheral surface of the photosensitive drum 6 by a print head described later. A developing unit 9 for forming a toner image by means of a replaceable unit as one block, and a transfer unit 10 for transferring the toner image formed on the peripheral surface of the photosensitive drum 6 to a sheet conveyed from a sheet feeding unit 11. 12, a paper feed roller for transporting the paper by rotation in the direction of the arrow, 13 a turn guide for reversing the transport direction of the paper, 14 a fixing device for fixing the toner image on the paper, 15 a toner image fixed on the paper. A face-up tray 16 for stacking sheets in a face-up state is a conveyance path switching member that conveys the sheets to a face-down tray described below by performing a switching operation.

The upper body 3 integrally includes a print head 17 which is a member of an image forming portion when opened, and brings the print head 3 to the state 3 'shown by the two-dot chain line and the print head 17 to the state 17'. The print head 17 irradiates the peripheral surface of the photosensitive drum 6 with image light to form an electrostatic latent image on the peripheral surface, and the distance to the peripheral surface of the photosensitive drum 6 is severe due to the depth of focus. Required. Reference numeral 18 denotes a face-down tray which is sequentially stacked with the printing surface of the above-mentioned paper facing downward, and is brought into the state of 18 'as the machine body 3 is opened as in 3'.

In the image forming apparatus 1 as described above, the print head
There are various types such as 17 using a light emitting diode or liquid crystal, and in any case, the distance between the print head 17 and the peripheral surface of the photosensitive drum 6 varies even though the degree is different. It must not be. Accordingly, as one of means for determining the distance between the print head and the photosensitive drum without variation, for example, FIGS.
As shown in the figure, there is a print head in which a roller is interposed as a spacer.

In the figure, reference numeral 19 denotes a photosensitive drum rotatably supported on a chassis 20 of the image forming apparatus main body by a shaft 19a, 21 denotes a support member fixed to a chassis separate from the chassis 20, and 22 denotes a support member. A fixed shaft 23 mounted on the support member 21 is slid on the fixed shaft 22 by a head end 23a, and is urged by a compression spring 24 so as to be pressed downward or against the photosensitive drum 19. Head, 25 is the head end
This roller is rotatably connected to 23a.

The print head 23 can come into contact with and separate from the photosensitive drum 19 within the operating range of the head end 23a allowed by the fixed shaft 22. Therefore, the print head 23 is pressed against the photoreceptor drum 19 via the roller 25 in a state where the compression spring 24 is deflected so that there is a margin within this operation range, so that the print head 23 The distance from the body drum 19 is determined.

The photoreceptor drum is made of a relatively soft material such as aluminum, and when a certain degree of impact is applied, scars or the like are likely to remain on the portion. Therefore, it is necessary to avoid hitting the surface of the drum 19 with another object.

As described above, in the image forming apparatus 1 of the type that opens and closes the upper body 3 and the lower body 2, the roller 25, which is a part of the print head 23, and the surface of the photosensitive drum 19 come into contact with and separate from each other when opening and closing. In the case of the type, a dent may remain on the contacting / separating portion. In particular, there is no problem if the shutter is closed gently by manual operation, but if the upper body 3 is strongly closed, the photoconductor may be largely recessed at the contacting / separating portion. there were. In this case, the print head 23 shown in FIG. 3 has some impact absorbing effect due to the compression spring 24, but cannot completely solve the above problem.

If the distance between the print head 23 and the photoconductor drum 19 is incorrect, the focus of the image light is deviated and the image formation loses sharpness and the image is degraded.
Is attached to the print head 25 to keep the distance to the photosensitive drum 19 constant.However, when the photosensitive drum 19 becomes uneven due to the collision between the photosensitive drum 19 and the roller 25 as described above, the roller 25 is With the rotation of the photosensitive drum 19, the uneven surface is traced, and the distance between the print head 23 and the peripheral surface of the photosensitive drum 19 becomes unstable. Therefore, the print head 23 and the photosensitive drum
The distance from the peripheral surface 19 is guided by the rollers 25 to cause a distance error, which causes a problem of deteriorating the image.

The problem caused by the impact when the upper fuselage 3 is severely closed is also applicable to other parts other than the above, and such repeated impact may cause a deviation in the set position or a screw in a fastening part. Causes various problems such as loosening and backlash.

[Purpose of the invention]

In view of the above-mentioned conventional disadvantages, the present invention relates to an opening / closing buffer mechanism typified by an image forming apparatus in which a photosensitive drum and a print head are separated from each other, the opening / closing buffer mechanism being connected to be openable and closable about a fulcrum. Provided is an opening / closing buffer mechanism configured to reduce a shock between members generated when a photosensitive drum, which is a member provided in each component, and a print head approach each other when the first component and the second component are closed. The purpose is to:

[Points of the invention]

According to an aspect of the present invention, there is provided an image carrier having a first body having an image carrier and an abutting portion for abutting on a surface of the image carrier to determine a reference distance. A second body including a print head that outputs a signal corresponding to image information on the surface thereof, and a spring member that biases the print head in a direction in which the contact portion of the print head contacts the image carrier surface, In the opening / closing buffer mechanism of the image forming apparatus, the fixing unit and the moving unit are slidably provided with each other, and the moving unit is interposed between the fixing unit and the moving unit and moves with the fixing unit. When the sliding speed of the portion is high, a first damping force is generated, and when the sliding speed is low, a second damping force smaller than the first damping force is generated. Away from the fixed part and the moving part And a return spring having a restoring force greater than the second damping force to urge the fixed portion and the moving portion to restore the relative position to the reference state. A fixed portion is disposed on the print head, and the moving portion in the reference state at the time of closing the first body and the second body is in contact with the surface of the image carrier and the contact portion. The image carrier body surface and the abutting portion may be provided at a position where the abutting portion does not abut against the first body before the predetermined time elapses from the moment when the closing is completed, or the damper member A fixed part is disposed on the first body, and the moving part in the reference state at the time of closing the first body and the second body is in contact with the surface of the image carrier and the contact part. A predetermined time has passed since the moment when the print head was brought into contact with the print head and the closing was completed. Until the surface of the image carrier and the contact portion are not in contact with each other, and the sum of the first damping force of the viscous fluid and the restoring force of the return spring is The biasing force of the spring member is made larger than the biasing force of the spring member, and the sum of the second damping force of the viscous fluid and the restoring force of the return spring is made smaller than the biasing force of the spring member. The present invention is characterized in that the return spring is set to be larger than the restoring force to reduce an impact at the time of contact between the surface of the image carrier and the contact portion of the print head.

〔Example〕

 Hereinafter, the present invention will be described with reference to an illustrated embodiment.

1 (a), 1 (b) and 1 (c) are sectional views of an embodiment for explaining the present invention.

Embodiments of the present invention shown in FIGS. 1 (a), (b) and (c) will be described below in the case where they are applied to the image forming apparatus 1 shown in FIG. Common members are used except for members described as
The illustration of the entire image forming apparatus and the description thereof are omitted to avoid the description from being duplicated and complicated.

In the figure, reference numeral 26 denotes a photosensitive drum as a first member having a drum shaft 26a, and 27 is fixedly attached to the lower body 2 (shown in FIG. 2) and pivotally supports the drum shaft 26a so as to freely rotate. A subframe 28 having a drum holding portion 27a and constituting a first component of the opening / closing mechanism together with the lower body 2;
Is a frame spring receiver fixedly attached to the upper body 3 (shown in FIG. 2) as a second component of the opening / closing mechanism and supporting the print head spring 29 composed of a compression spring so as not to be displaced. The upper frame 31 is fixed to the frame spring receiver 28.A head spring receiver 31a that supports the print head spring 29 so as not to be displaced is fixed to the upper frame 31. A print head 32 as a second member; a piston 32a having one end fixedly attached to the print head 31;
The cylinder spring 3 is slidably mounted on the cylinder 32b, and the slide operation is controlled by viscous resistance of a fluid such as oil or air.
It is a damper consisting of 2c. In the above, the cylinder spring 32
c has an operation behavior that is weaker than that of the print head spring 29.

FIGS. 1A, 1B, and 1C show the photosensitive drum 1 when the image forming apparatus 1 (shown in FIG. 2) is viewed from the front, that is, from the left side of FIG. 2 to the right side of FIG. FIG. 1 is a schematic cross-sectional view in which the cross section of FIG.
In order to provide a detailed description in the drawing, reference numeral is replaced with reference numeral 1.
This is explained in 26.

FIG. 1A shows a state where the upper body 3 is being operated in the closing direction and has not yet been brought into contact with the lower body 2. The print head 31 is urged in the direction of the arrow a by the print head spring 29, and is therefore urged downward in the figure as much as possible (more urging is blocked by the upper frame 30 as shown). The cylinder 32b of the damper 32 is supported by the body 3 and the cylinder spring 32c
, Thereby operating up to the limit of the operation stroke.

FIG. 1B shows the state at the moment when the upper body 3 abuts on the lower body 2 and the closing is completed (the upper body 3 is locked to the lower body 2 by a lock mechanism not shown), and the damper 32 is provided.
3 shows a state at the moment when the tip portion of the frame abuts on the sub-frame 27. 1A, the closing operation of the upper body 3 continues, and when the upper body 3 is lowered, the print head 31 is also lowered via the print head spring 29.
In FIG. 1B, the cylinder 32b first comes into contact with the subframe 27 fixed to the lower body 2 at the moment of closing in FIG. 1B, so that a large fluid viscous resistance when the piston 32a of the damper 32 is going to descend. (The resisting force acts to compress the print head spring 29 against the urging force of the print head spring 29) as shown in FIG.
(The print head spring 29 is compressed in the direction of the arrow b in the drawing), and its lowering is temporarily prevented. Accordingly, the roller 31b of the print head 31 does not abut the photosensitive drum 26 at the moment of closing in FIG. 1B. After this, print head 31
Indicates that the print head spring 29 is
By acting so as to further compress the compression spring of the cylinder spring 32c assembled between the cylinder spring 32b and the cylinder spring 32b, the cylinder spring 32c slowly comes into contact with the photosensitive drum 26 (FIG. 1 (c)). In this case, since the print head spring 29 is stronger than the cylinder spring 32c, the cylinder spring 32c is charged.

Immediately before the body 3 completes closing the lower body 2 as described above, the print head 31 is first received by the damper 32 and descends while decreasing the descending speed. Since the upper fuselage 3 is not received by the lower fuselage 2 and does not come into contact with the photosensitive drum 26 at the same time, the collision force is reduced.

In the state shown in FIG. 1C, the print head 31 is again urged in the direction of arrow a by the print head spring 29, but is fixed to the upper body 3 and the upper frame 30 supporting the print head 31 is moved. Leave the support and leave, so roller 31b
Is the cylinder spring 32c from the spring torque of the print head spring 29
Is pressed against the peripheral surface of the photosensitive drum 26 with a torque having a value obtained by reducing the spring torque of the photosensitive drum 26, and the distance between the print head 31 and the peripheral surface of the photosensitive drum 26 is kept constant.

In the embodiment described above, the print head as the second member is mounted on the upper body as the second component,
Although the photoconductor drum, which is the first member, is attached to the lower body, which is a component, the present invention is not limited to this.

That is, in the present invention, the shock caused when the first member and the second member approach each other and the two members come into contact with each other is relieved by the damper interposed therebetween. In the above, the first member (photosensitive drum) may be attached to the second component (upper body), and the second member (print head) may be attached to the first component (lower body).

In the above embodiment, the damper is mounted on the second member (print head) side. However, in a shell open type image forming apparatus, the damper is mounted on the first component (lower body) side. However, the present invention can be implemented.

Further, in the above-described embodiment, the photosensitive drum is used as the image carrier and the photosensitive drum is irradiated with image light as the print head. Of course, it is not limited.

[Effect of the invention]

According to the present invention, the first member and the second member provided on the first component and the second component that are openably and closably connected to each other are provided before the two members come into contact with each other when the opening and closing mechanism is closed. Since the shock absorbing function of the damper member acts, mutual contact is performed gently, damage at the time of contact can be prevented, and the durability of the device provided with the opening / closing buffer mechanism can be greatly increased.

Therefore, if the present invention is applied to an image forming apparatus in which an image carrier and a print head are provided on a first component and a second component which can be opened and closed with respect to each other and are configured to be able to freely contact and separate,
In particular, the surface of the image carrier is reliably prevented from being damaged by the contact between the image carrier and the print head, and the life of the image forming apparatus can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a), 1 (b) and 1 (c) are schematic sectional views of an embodiment of the present invention, FIG. 2 is a schematic sectional view schematically showing an image forming apparatus, FIG. 3 is a front view showing a conventional example, and FIG. 4 is a view from the direction of arrow IV in FIG. 26 photoconductor drum, 27 subframe, 28 frame spring receiver, 29 printhead spring, 30 upper frame, 31 printhead, 31a head spring receiver, 32
…… Head damper, 32a …… Piston, 32b …… Cylinder, 32c …… Cylinder spring.

Claims (1)

(57) [Scope of request for utility model registration] A first body provided with an image carrier, and a contact portion for contacting the surface of the image carrier to determine a reference distance, the surface of the image carrier corresponding to image information. A second body including a print head that outputs a signal and a spring member that urges the print head in a direction in which the contact portion of the print head comes into contact with the surface of the image carrier; In the opening and closing buffer mechanism of the image forming apparatus freely connected, a fixed portion and a moving portion slidably provided with each other, and a sliding speed between the fixed portion and the moving portion interposed between the fixed portion and the moving portion is high. A viscous fluid that generates a first damping force and generates a second damping force smaller than the first damping force when the sliding speed is low, and allows the fixed portion and the moving portion to slide, Urging the fixed part and the moving part in a direction away from the fixed part, A return spring having a restoring force larger than the second damping force for restoring a relative position with respect to a moving portion to a reference state, wherein the fixing portion of the damper member is disposed on the print head. When the first body and the second body are closed, the moving part in the reference state contacts the first body prior to the contact between the surface of the image carrier and the contact part. And providing the fixing portion of the damper member to the first body at a position where the surface of the image carrier and the contact portion do not contact each other for a predetermined time from the moment of completion of closing. Set up
During the closing operation of the first body and the second body, the moving part in the reference state contacts the print head and closes before the contact between the surface of the image carrier and the contact part. The image bearing member is provided at a position where the surface of the image bearing member and the contact portion are not in contact with each other for a predetermined time from the moment of completion, and the first damping force of the viscous fluid and the return spring The sum with the restoring force is greater than the urging force of the spring member,
The sum of the second damping force of the viscous fluid and the restoring force of the return spring is smaller than the urging force of the spring member,
An opening / closing buffer, wherein an urging force of the spring member is set to be larger than the restoring force of the return spring, and an impact at the time of contact between the surface of the image carrier and the contact portion of the print head is reduced. mechanism.