JPH0529912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, more specifically, an image forming apparatus that forms an electrostatic latent image corresponding to the original image by projecting the original image onto the surface of an image carrier such as a photoreceptor, and then uses a developer to form an electrostatic latent image corresponding to the original image. The present invention relates to various image forming apparatuses including electrophotographic copying apparatuses that obtain copies by transferring the toner images onto transfer paper.

In this type of apparatus, for example, as shown in FIG. A charge eliminator 4 for erasing the latent image and a plurality of other chargers 5 and 6 are arranged close to the periphery of the photoreceptor 1. Further, a developing sleeve 9 of a developing device 7 that supplies toner to the surface of the photoreceptor 1 is also arranged close to the photoreceptor 1 . In addition, a cleaning blade 11 of a cleaner 10 that scrapes off and cleans the remaining toner on the photoreceptor 1 is arranged in contact with the photoreceptor 1.

These accessories are acting means that act on the image bearing member. For example, a charger uses a thin charged wire (usually a tungsten wire, etc.) to charge or remove electricity from the photoreceptor, but the contact between the charged wire and the photoreceptor is Since the surface potential on the photoreceptor changes sensitively depending on the distance, the distance and parallelism between the charged line and the photoreceptor are one of the things that requires precision in an electrophotographic apparatus.

Particularly in the case of a type of photoconductor that has an insulating layer on the surface of the photoconductor, a charger that removes static electricity at the same time as image exposure uses several grids between the charging wire and the photoconductor to ensure the contrast of the latent image. Use a charged charger. This type of charger requires greater precision in the distance and parallelism between the grid and the photoreceptor.

In addition, even in the so-called Carlson psocess electrophotographic method, which uses a photoreceptor without a surface insulating layer,
In the charger 2 that charges the photoreceptor to provide photosensitivity (primary charging), it is preferable to provide a grid 2b together with the charging wire 2a. By applying a bias voltage to the grid 2b, it is possible to remove the image memory generated on the photoreceptor during the previous image formation, and it is also possible to perform extremely uniform primary charging. This grid also needs to be accurately positioned at a distance from the photoreceptor surface.

Conventionally, in order to perform such positioning, the charger 2 is slid along a back rail 13 that is passed between a vertical front plate and a vertical rear plate (not shown) of the main body of the electrophotographic apparatus, as shown in FIG. 2, for example. Supported for free movement. Therefore, when it is necessary to clean the charger or replace the photoreceptor, the charger can be pulled out parallel to the central axis of the photoreceptor. That is, the charger 2 can be pulled out parallel to the central axis of the photoreceptor from a position close to the photoreceptor 1 shown by the solid line in the figure to another position in the main body of the electrophotographic apparatus (indicated by the chain line 2'). I'm starting to be able to do it.

However, such a method has the disadvantages that (1) positional accuracy between the charging wire or grid and the photoreceptor is difficult to obtain, and (2) the surface of the photoreceptor is easily damaged when inserting and removing the charger. The reason why positional accuracy is difficult to achieve is that there are variations in the dimensional accuracy of the block that supports the charging wire of the charger, the shield plate, the rail where the charger is inserted and removed, the side plate, etc. This is because it adversely affects positional accuracy. In order to alleviate this variation in positional accuracy, it is common practice to attach a height adjustment mechanism to the block that supports the charging wire to change the distance between the charging wire and the photosensitive drum, but the mechanism is complicated and the adjustment is difficult. The annoyance remains. The problem of the possibility of damaging the photoconductor when inserting and removing the charger is that in the case of a charger with a grid, the distance between the grid and the surface of the photoconductor is usually 0.8~
Since it is around 1.5mm, it is more likely to occur.

To prevent damage to the photoconductor, pull out the photoconductor 1 and its accessories as a unit as shown in Figure 3, then open the charger 2 in the direction of the arrow and move it to the position indicated by the chain line 2''. A configuration has also been proposed in which the photoconductor is removed after the photoconductor has been removed. However, it is time-consuming to remove the photoconductor, and it is difficult to achieve positional accuracy between the photoconductor and charger. You have to bring out the whole thing, which is tedious.

Also, when pulling out the photoconductor from the main body of the device,
It is necessary to prevent the surface of the photoreceptor from being damaged by members adjacent to the photoreceptor.

The present invention attempts to solve this problem,
An object of the present invention is to provide an image forming apparatus in which a photoreceptor can be pulled out from an apparatus main body without damaging the surface of the photoreceptor.

To achieve this object, the present invention includes an image carrier that can be taken in and out of the device main body in the generatrix direction;
In an image forming apparatus that is capable of forming an image on a recording material and has an action means that acts on the image carrier at a predetermined position adjacent to the image carrier within the apparatus main body, the action means is capable of pulling out the image carrier. The device is characterized in that it moves away from a predetermined position in a direction substantially perpendicular to the generatrix direction while remaining within the device main body.

Examples of the present invention will be described in detail below.

FIG. 4 shows the main parts of an electrophotographic apparatus to which the present invention is applied. In the figure, 20 is the photoreceptor 1
It represents a part of the frame that supports the device, and is removably fitted into the front plate 22 and back plate 24 of the main body of the device.
By pulling the handle 20a, it can be pulled out together with the photoreceptor 1 in the direction of arrow X, that is, in the direction of the generatrix of the photoreceptor. A charger holding rail 25 supports the charger 2 in a slidable manner. This rail 25
is continuous from the back plate 24 to the front plate 22 of the device main body, and the back end is loosely fitted into the hole 24a of the back plate 24 and is folded back on the back side of the back plate 24 to prevent it from coming off. A front plate 25 is loosely fitted to the front end, and a spring 28 is held between the front plate 25 and a dowel 27 attached to the front plate 22. The figure shows the charger 2 pulled out slightly, but when the device is used, the charger 2 is pushed further in the direction of arrow X'.
That is, the input terminal/guide rod 30 on the back side of the charger 2 is inserted into the center 24b of the hole in the back plate 24 along the chain line, and the protrusions 31, 31 on the back side are inserted into the ends 24c, 24c of the hole. inserted into. L-shaped sliding members 32a and 32b attached to the upper side of the charger 2
are both inserted along the chain line and engaged with the rail 25. A handle 33 is attached to the front end of the charger 2, and pins 34a and 34b implanted on both sides of the handle 33 are inserted along the chain lines to align the guide grooves 35a and 35b of the frame 20 horizontally. They are located in different parts. Pins 34a and 34 at that time
b is indicated by a chain line.

In addition, the frame body 20 holds a pre-transfer charger 50 and a transfer charger 51.

FIG. 5 shows the surroundings of the charger 2 and the holding rail 25, where a shows the side surface, b shows the grid side, and c shows the guide rod side.

The charger 2 has shields 37 on three sides.
A charging wire 2a is stretched at the center, and a grid wire 2b is stretched near the surface of the front opening. Both ends in the longitudinal direction are closed with blocks 41 and 42. The back block 41 is fastened to the top plate of the shield 37 with screws 43, and the front block 42 is fastened with screws 44. A leaf spring 45 is attached to the rail 25 holding the charger 2 at a position facing the screw 43.
A leaf spring 46 is also attached at a position opposite to the charger 4 to bias the charger 2 downward.

FIG. 7 shows the holding rail 25 when the charger 2 is pulled out and removed. The holding rail 25 is in a state where it is pulled up by the spring 28.

Operations when inserting and removing the charger 2 and removing and inserting the photoreceptor 1 together with the frame 20 in the above configuration will be described.

When storing the charger 2 in the fixed position of the device, first move the sliding member 32b on the back side of the charger 2 to the rail 25.
to engage. Then, when you push in the charger 2, the fourth
The state will be as shown. When pushed in further, the sliding member 32a on the near side engages with the rail 25, and the guide pins 34a, 34b advance guided by the guide grooves 35a, 35b, respectively. On the other hand, the guide rod 30 and the protrusions 31, 31 on the back side are inserted into the holes 24b and 24 of the back plate 24, respectively.
c, 24c and advances, and the end of the charger 2 hits the back plate 24 and stops. At this time, the guide pin 34
A and 34b resist the upward bias by the spring 28 and advance along the guide grooves 35a and 35b until they reach the position indicated by the chain line. Therefore, the close positional relationship between the drum 1 and the charger 2 is such that the guide pin 34 of the charger 2 is close to the drum 1 on the front side.
a, 34b and the guide grooves 35a, 35b of the frame 20
made by the upper side of the horizontal part of. Since the rear side is biased downward by leaf springs 45 and 46 (see FIGS. 5 and 7), the lower side of the protrusion 31 of the charger 2 and the lower side of the hole 24c of the rear plate 24 act as a force.

When pulling out the charger 2 for repair or the like, pull the handle 33 toward you. Then, the charger 2 is pulled out while moving away from the photoreceptor 1 in accordance with the upward inclination of the guide grooves 35a and 35b, contrary to the push-in process.

Next, the photoreceptor 1 (image carrier) which is a feature of the present invention
The operation of the charger 2 (acting means) when it is pulled out will be explained.

First, if the photoreceptor 1 needs to be repaired, the photoreceptor 1 is pulled out together with the frame 20. Since the guide grooves 35a and 35b are inclined upward as they go deeper, as the frame 20 is pulled out accordingly, the charger 2 held on the rail 25 is moved by the spring 28.
It is pulled away from the photoreceptor 1.

This state is shown in FIG. By further pulling out the frame 20 from here, the photoreceptor 1 can be removed together with the pre-transfer charger 50 and the transfer charger 51.

In this way, when the photoreceptor 1 and the charger 2 are in the fixed position within the apparatus main body, the positional relationship is precise, so that extremely good charging can be achieved. Further, as the photoreceptor 1 is pulled out in the generatrix direction, the charger 2 moves in a direction substantially perpendicular to the generatrix direction while remaining within the device main body so as to move away from the predetermined position where it acts on the photoreceptor 1. Therefore, the surface of the photoreceptor 1 is not damaged by the charger 2.

Furthermore, as shown in this example, the photoreceptor 1
In addition, when the charger 2 is made to be able to be pulled out from the main body of the device in the direction of the bus bar, the charger 2 can be moved not only in the direction of the bus bar but also in a direction substantially perpendicular to the bus bar direction. For example, photoreceptor 1
It is clear that it is more effective in preventing scratches on the surface. Similarly, when pulling out the photoreceptor 1, there is no risk of damaging it.

Also, when the photoreceptor 1 is pulled out, the charger 2
is left on the main body of the device. Therefore, photoreceptor 1
Since the drum is exposed and there is nothing to obstruct when taking it out or setting it from above when replacing the drum, there is no need for the conventional complicated procedure of temporarily retracting the charger 2 located above. If the photoreceptor touches the charger 2 easily, the surface of the photoreceptor and the charger 2 may be damaged.
There is no fear of breaking it.

FIG. 6a shows another embodiment in which guide pins 34a, 34b, guide grooves 35a, 35b, and b are protrusions 31, 31, and deep plate holes 24c, 24c. In the figure, O is the center of the photoreceptor 1, and each of them is on a circular arc with O as the center. Therefore, even if the insertion position of the charger 2 is slightly shifted to the left or right, the photoreceptor 1 and the charger 2 are always located at a position separated by a certain distance.

Note that the present invention is not limited to the charger 2, but also includes components left in the copying machine, such as the potential sensor 13, the developer 7, and the cleaner 11, such as those shown in FIG.
It can also be applied to other chargers.

By the way, in the charger 2 of the above embodiment, the grid bias application method is as follows. Grid 2b serves as a control grid. For example, when attempting to charge the surface of the photoreceptor 1 to +500V, by applying a bias of +500V to the grid, the photoreceptor 1 will be uniformly charged to +500V.
Therefore, a positive charge of +500V is always maintained regardless of environmental changes or the memory history of the previous image formation on the photoreceptor 1, resulting in a preferable result. A conventional method for grid biasing is to connect the grid to a +500V voltage transformer, for example. In this embodiment, from the viewpoints of cost, safety, and space, a method was adopted in which the 500V varistor D and the grid 2b were connected, and +500V was applied to the grid 2b with a self-bias using the corona from the discharge wire 2a.

In some cases, two or more chargers are kept for one copying machine for maintenance purposes, and they are replaced when the copying condition deteriorates or the wire breaks. If you incorporate a varistor into the charger,
The installation space for the barista and the cost of the barista are 2
double or multiply. Further, there is a problem that the charging potential by the charger changes due to variations in the voltage of the varistor. In consideration of this point, in the embodiment, the varistor is not incorporated into the charger, but is placed on the copying machine side.

Specifically, the details and installation of the charger 2 will be explained below with reference to FIG.

The grid 2b starts from the protrusion 42a on the block 42, is successively suspended between the front block 42 and the back block 41, and is fixed at the end with a screw 47. In order to apply an appropriate tension, screw in the screw 48 with the screw 44 slightly loosened, pull the front block 42 toward you, and fix the screw 44 in an appropriate position. In this state, the grid 2b is not in electrical contact with the shield plate 37, which is a member to be grounded, and the discharge wire 2a. When the charger 2 is inserted along the rail 25, the leaf spring 55 comes into contact with the screw 47. The leaf spring 55 is fixed with a screw 56 of the front cover 20, and one end of the varistor D is connected to the screw 56. The other end of the varistor D is fixed by a screw 57 to the front plate 22, which serves as a ground portion. Therefore, the grid 2b is connected to the discharge wire 2a.
When the discharge starts, the varistor voltage (500V for 500V) is applied as a self-bias.

Since the charger of this embodiment is configured as described above, an expensive high-voltage power source is not required, and one varistor is required for each copying machine. Grid bias is applied only when the charger is inserted and during discharge. If a grid bias is applied to the charger 2 using a high-voltage transformer, for example, when the surface potential of the photoreceptor due to the other charger 4 becomes close to 1KV, the distance between the grid 2b of the charger 2 and the photoreceptor 1 is 1 mm. Moreover, since the grid 2b is grounded when no discharge is occurring, a reverse discharge occurs from the photoreceptor 1 to the grid 2b. Therefore, the potential sensor 13 could not accurately measure the surface potential of the photoreceptor 1 due to the discharge of the charger 4. However, in the configuration according to this embodiment, since the grid is grounded via the varistor D, reverse discharge is less likely to occur, and while the charger 2 is inserted into the grid, the potential due to other chargers can be measured.

As explained above, in the present invention, the operating means adjacent to the image carrier remains in the apparatus main body and is substantially perpendicular to the generatrix direction so as to move away from a predetermined position in accordance with the pulling operation of the image carrier. Since the image bearing member moves in a certain direction, it is possible to prevent the surface of the image bearing member from being damaged when the image bearing member is taken out.

[Brief explanation of the drawing]

Figure 1 is a schematic front view of the electrophotographic device, Figure 2.
FIG. 3 is an explanatory diagram of the installation of a charger in a conventional electrophotographic apparatus, FIG. 4 is a perspective view of the main part of an electrophotographic apparatus to which the present invention is applied, and FIG. 5 is a diagram showing an embodiment of the charger. , FIG. 6 is a diagram showing another embodiment, FIG. 7 is a side view of the charger holding rail, and FIG. 8 is a perspective view of the photosensitive member pulled out. 1 is a photoreceptor, 2 is a charger, 20 is a frame, 25 is a charger holding rail, 34a, 34b are guide pins, and 35a, 35b are guide grooves.

Claims (1)

[Scope of Claims] 1. An image carrier that can be taken in and out of the device body in the generatrix direction, and an action means that acts on the image carrier at a predetermined position adjacent to the image carrier in the device body, In an image forming apparatus capable of forming an image on a recording material, the acting means remains within the apparatus main body and moves away from the predetermined position in response to the drawing operation of the image carrier in the generatrix direction. An image forming apparatus that moves in a substantially vertical direction.