JPH01244472A - Process cartridge and image forming device - Google Patents

Abstract

PURPOSE:To reduce the process cartridge in size and weight by turnably supporting a developing device around a pressurizing center and arranging a resilient means opposite to the side where an image carrier is arranged between the developing device and a housing, centered about the pressurizing center. CONSTITUTION:The process cartridge 1 is removable to the image forming main body, and parts such as a photosensitive drum 3, a cleaning device 7 and an electrostatic charger 8 are supported on the housing 2 of the cartridge 1. The developing device 9 is energized counterclockwise (in a direction shown by an arrow (a)) with resilience by two compression coil springs 11 and 11 arranged between the housing 2, whereby a developing sleeve 9 is constantly brought into contact with the photosensitive drum 3 with a prescribed pressure. The compression coil springs 11 and 11 are compactly arranged on both sides of an exposure window 2b formed on the using 2. Thus, the process cartridge 2 can be reduced in size and weight.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a process cartridge that is configured to be detachably attached to an image forming apparatus main body, and an image forming apparatus such as a copying machine or a laser printer that includes the process cartridge. .

(Prior Art) A conventional process cartridge 101 is shown in FIGS. 6 and 7.
The process cartridge 101 has a photosensitive drum 1 as an image carrier in its housing 102.
03. A developing device that includes a charger 108 that uniformly charges the circumferential surface of the photosensitive drum 103 to a predetermined polarity, a developer container 109a, and a developing sleeve 109b, and that develops the latent image formed on the photosensitive drum 103. container 109 and photosensitive drum 1
A cleaning device 10 that removes the developer attached to the surface of the cleaning device 03
7 are compactly housed in a predetermined mutual arrangement, and can be attached to and detached from the main body of the image forming apparatus.

By the way, as shown in FIG. 7, the photosensitive drum 103,
The charging device 10B and the cleaning device 107 are supported by a side plate 112, and the developing device 109 is supported by a side plate 113.
These are mutually rotatable around the center, and are urged in the direction of attracting each other by a tension coil spring (sleeve pressure spring) 111 stretched between pins 114 and 115 protruding from each. As a result, the spacer portions c, c (see FIG. 6) at both ends of the developing sleeve 109b are brought into pressure contact with the photosensitive drum 103, and the developing sleeve 109b is pressed against the photosensitive drum 103.
The distance between the photosensitive drum 103 and the photosensitive drum 103 excluding the spacer portions c and c is always kept constant.

(Problem to be solved by the invention) However, the above-mentioned conventional process cartridge 101
As described above, the heavy photosensitive drum 103, the charger 108, and the cleaning device 10 are mounted on the side plate 112.
7 and suspend them from the developing screen 109b side by the tension coil spring 111. Therefore, the tension coil spring 111 requires a large tensile force, and therefore the coil diameter of the tension coil spring 111 and As the diameter of the coil wire increases, the installation space becomes a problem, leading to an increase in the cost of the process cartridge 101.

Furthermore, since the tension coil spring 111 is disposed on the outer side of the circle in the longitudinal direction of the photosensitive tram 103, the longitudinal dimension (width dimension) of the process cartridge 101 becomes large, resulting in an increase in the size of the process cartridge 101. There was a problem in that the size of the image forming apparatus was increased.

The present invention has been made in view of the above problems, and an object thereof is to provide a process cartridge and an image forming apparatus that can be made smaller and lighter by making the sleeve pressure spring smaller and rationally arranging it. It is in.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a process cartridge which is configured to be detachably attached to the main body of an image forming apparatus and which incorporates at least an image carrier and a developing device between a housing. , the developing device is supported so as to be rotatable clockwise during pressurization, and a resilient means is interposed between the developing device and the housing, and the resilient means is moved toward the center of the pressure by the image carrier. It is characterized by being placed on the opposite side to the side on which it is placed.

Further, the present invention constitutes an image forming apparatus including the above-mentioned process cartridge.

(Function) Since the resilient means, the image carrier, and the developing sleeper that is pressed against the image carrier are arranged on both sides of the center of pressure, the developing device is held in place by the resilient means such as a compression coil spring. When the developing sleeve is biased in this direction, the developing sleeve disposed on the opposite side of the resilient means with respect to the center of pressure is pressed against the image carrier with a predetermined pressure. However, if the length of action of the elastic force exerted on the elastic means or developing device and the pressing force of the developing sleeve from the center of pressure is set appropriately, the elastic force required for the elastic means can be reduced by the so-called lever principle. This makes it possible to reduce the dimensions of the compression coil springs, etc. that make up the resilient means, and to enable their rational arrangement, thereby reducing the size and weight of the process cartridge and, by extension, the image forming apparatus. It is possible to aim for

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 8 is a longitudinal cross-sectional view of a laser beam printer according to the present invention. In the laser beam printer, a large number of cut sheets P... are stacked on a paper feed tray 41, and each cut sheet P is The paper is conveyed to the image forming section by rollers 42 and conveyance rollers 43, the image is transferred by transfer roller 44, then guided to fixing device 45 where it is fixed by a heat roller, and then transferred to an output tray outside the apparatus by discharge roller 46. 4
7 is discharged onto the top.

By the way, the paper feed section including the paper feed tray 41, the paper feed roller 42, the transport section including the transport roller 43, the fixing section including the fixing device 45, the ejection roller 46, and the paper ejection section including the paper ejection tray 47 are in the apparatus. It is pivotally supported by a base B at an axis A, and is divided at the position shown by the dashed line shown in the figure, and is configured to be openable and closable.

Further, the image forming section constitutes a ridge 1 on a car 1 that integrates a photosensitive tram 3, a cleaning device 7, a charger 8, and a developing device 9. The charger 8 can charge the photosensitive tram 3 by applying an electrical bias to the conductive elastic body 1, such as a conductive rubber roller.

By the way, the cartridge 1 is replaced with a new one after a certain amount of image formation, taking into account the lifespan of the photosensitive 1 ram 3, the lifespan of the cleaning freight, the lack of toner, etc. is done as follows. That is, as shown in FIG. 9, when a part K of the exterior cover that includes paper feeding, conveyance, fixing, and paper ejection sections is opened, the cartridge J is configured such that it can only be inserted and removed with the part K of the exterior cover opened. Therefore, the operator can take out the cartridge 1 from the main body in a direction perpendicular to the drum generatrix direction. Further, a new cartridge 1 is installed in the main body by operating in the opposite manner to the above-mentioned removal process, and after installation, if the outer cover part K is closed, the cartridge 1 to the cartridge 1 are moved to the transfer roller 44.
It is securely set in place by receiving pressure from Incidentally, when the exterior cover part K is opened, as shown in FIG. 8, the paper discharge tray 47 (see FIG. 8) is removed and the paper feed tray 41 is folded.

FIG. 1 is a longitudinal sectional side view of a process cartridge 1 according to the present invention, and FIG. 2 is a perspective view of the same process cartridge 1. Inside the housing 2 of the process cartridge 1,
A photosensitive drum 3 serving as an image carrier is arranged on the right side in FIG. The housing 2 is formed with an opening 2a through which a portion of the photosensitive drum 3 is exposed, and the opening 2a is opened and closed by a shutter 4 that rotates around a shaft 4a. That is, when the process cartridge 1 is installed in the main body, the shutter 4 opens upward as shown by the chain line in FIG. When the process cartridge l is removed from the main body,
The shutter 4 is closed as shown by the solid line in FIG. 1 to prevent damage to the photosensitive drum 3 and deterioration due to external light.

In addition, a rectangular slit-shaped exposure window 2 having a predetermined width is provided on the opposite side of the housing 2 from the side where the first part 2a is provided.
The exposure window 2b is formed in the housing 2.
A substantially horizontal optical image exposure optical path 6 extending from the photosensitive tram 3 to the photosensitive tram 3 is formed. A cleaning device 7 and a charging device 8 are disposed above the optical image exposure optical path 6, and a developing device 9 is disposed below it. The charger 8 is constituted by a contact charging roller that contacts the photosensitive tram 3 and rotates in the direction of the arrow in the figure, and the developer 9 is configured to make contact with the photosensitive tram 3 and a toner container 9a containing toner t therein. The developing sleeve 9b rotates in the direction of the arrow shown in the figure.

Incidentally, the photosensitive drum 3, cleaning device 7, charger 8, and other devices are supported by the housing 2, or the developing device 9 is rotatably supported with respect to the housing 2 around a shaft 10 that is the center of pressure. At the same time, the developing device 9 and the housing 2 are elastically biased in the counterclockwise direction (in the direction of the arrow a in the figure) by two compression coil springs 11 and 11, which are compressed and installed between the developing device 9 and the housing 2. The developing sleeve 9b is kept in constant contact with the photosensitive tram 3 under a predetermined pressure.

The compression coil springs 11, 11 are arranged compactly on both sides of the exposure window 2b formed in the housing 2, as shown in FIG. It is a space that arises.

In other words, the width of the optical image exposure light emitted from the image exposure device (not shown) increases toward the photosensitive drum 3 as shown in FIG. It is narrower than the width when irradiated, and therefore, a space is inevitably formed on both sides of the exposure window 2b. Therefore, disposing the compression coil springs 11, 11 in such a space is very rational for making the process cartridge 1 smaller and more compact.

Further, if the device arrangement as in this embodiment is adopted, the elastic force required for the compression coil springs 11, 11 is small, and the dimensions of these compression coil springs 11, 11 can be reduced. That is, as shown in FIG.
The elastic force of 11 is Fl, and the contact pressure of the developing sleeve 9b is F.
2, and the length of action from the shaft 10 to the forces Fl and F2 is <1. , sentence, the following equation holds due to the balance of moments.

F, X father 1 ” F2
1 is expressed by the following formula.

However, since □〉 stands again, the following magnitude relationship holds between forces F1 and F2.

FI F2 (3) As is clear from the above equation, the elastic force F required for the compression coil springs 11°11 with respect to the required contact pressure F2 of the developing sleeve 9b, (individual compression coil springs 11 F for
l/2) can be smaller than the contact pressure F2, and as a result, the dimensions (number of turns, winding diameter, and wire diameter) of the compression coil spring 11.11 can be small, and the process cartridge 1 and, by extension, the process cartridge It is possible to reduce the size and weight of the image forming apparatus to which the image forming apparatus 1 is attached.

By the way, in the above, the self-weight of the developing device 9 has been ignored, but if this is taken into consideration, the elastic force F1 can be smaller than the value expressed by the above-mentioned formula (2), and this means that each compression coil spring 11
This is further advantageous for downsizing.

In this embodiment, two compression coil springs 11 are arranged, one on the left and right sides of the exposure window 2b, but if the exposure window 2b is moved to either the left or right direction, one compression coil spring 11 is placed in the space created by this. Alternatively, a plurality of compression coil springs 11 may be arranged. Further, in this embodiment, the copying material P during image formation is conveyed to the process cartridge 1 through the path shown by the chain line in FIG.

By the way, in the second embodiment, a compression coil spring 11 is used as a means for biasing the developing device 9 in a predetermined direction.
, 11, or alternatively a torsion coil spring 21 at the same location as in the previous embodiment as shown in FIGS. 3 and 4.
．． 21 may be arranged. That is, the developing device 9 has a boss portion 9c.
, 9c are provided in a protruding manner, and the torsion coil springs 21 and 21 are passed through the boss portions 9c and 9c, and as shown in FIG. 3, one end 21a of each torsion coil spring 21 is engaged with the housing 2, and the other end 21b is By engaging a portion of the exposure window 9d of the developing device 9, the developing sleeve of the developing device 9 can be brought into contact with a photosensitive drum (both not shown) with a predetermined pressure. In addition, the same effect can be obtained by interposing a leaf spring 31 over substantially the entire width between the housing 2 of the exposure window 2b and the developing device 9, as shown in FIG. Note that in both FIGS. 3 and 5, 10 is an axis that should be the center of pressure.

(Effects of the Invention) As is clear from the above description, according to the present invention, since the resilient means, the image carrier, and the developing sleeve that is pressed against the image carrier are arranged on both sides of the center of pressure, the resilient By appropriately setting the length of the elastic force exerted on the developing device and the pressing force of the developing sleeve from the center of pressure, the elastic force required by the elastic means can be kept small by the so-called lever principle. This makes it possible to reduce the dimensions of the compression coil springs and the like constituting the resilient means and enable their rational arrangement, thereby making the process cartridge and, by extension, the image forming apparatus smaller and lighter. You can get the effect of being able to do it.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view of a process cartridge according to the present invention, FIG. 2 is a perspective view of the same process cartridge, FIG. 3 is a cross-sectional view of the main parts of the process cartridge showing a modified embodiment of the present invention, and FIG. A perspective view of the process cartridge,
5 is a perspective view of a process cartridge according to another embodiment, FIGS. 6 and 7 are vertical side views of a conventional process cartridge, FIG. 8 is a vertical side view of an image forming apparatus according to the present invention, and FIG. The figure is a cross-sectional view of the image forming apparatus showing how to replace the process cartridge. 1... Process cartridge, 2... Housing,
3... Photosensitive drum (image carrier), 9-... Developing device, 9
b...Developing sleeve, 10...Shaft (pressure center), 1
1... Compression coil spring (elastic means), 21... Torsion coil spring, 31... Leaf spring. Ward C'J So (2,1 Figure 3 Figure 4/

Claims (3)

[Claims] (1) It is configured to be detachable from the main body of the image forming apparatus;
In a process cartridge comprising at least an image bearing member and a developing device built into a housing, the developing device is rotatably supported around a center of pressure, and a resilient means is interposed between the developing device and the housing. . A process cartridge, wherein the resilient means is disposed on a side opposite to the side on which the image carrier is disposed with respect to the center of pressure. (2) The process cartridge according to claim 1, wherein the image carrier and the repelling means are arranged on the left and right sides of the optical path formed in the housing. (3) An image forming apparatus including the process cartridge installed in the main body.