Laser printers have become very popular, especially where fast printer output is desired. Other types of printers that operate on the same principle as laser printers, such as printers that utilize light-emitting diodes (LED's) instead of lasers, are also available and have become popular. A laser printer generally works as follows. An image transfer roller, which may also be referred to as a photoreceptor drum, a photoconductor drum, an organic photoconductor, an optical photoconductor, or a photoconductor, is pre-charged using a charge roller or corona wire. A laser then writes the desired image onto the photoconductor, electrostatically discharging the photoconductor according to the desired image. Meanwhile, a toner transfer roller, or developer roller, is coated with charged toner from a toner hopper, or toner cartridge sump.
Traditionally, laser printers maintained a small gap between the photoconductor and the developer roller and/or the charge roller. This is especially the case with black-and-white laser printers. However, more recently laser printers have had the photoconductor come into contact with the developer roller and/or the charge roller.
Photoconductors can be relatively hard, however. Therefore, if the relatively soft developer and/or charge rollers remain in contact with them constantly, especially during shipment of toner cartridges of which the photoconductors and these rollers are a part, these rollers can go out of round, developing flat spots. Such deformation of the rollers can result in image quality degradation. At best, the rollers regain their round shape over time, and image quality improves. At worst, though, the rollers retain their deformed shape, and image quality may not improve.
Furthermore, the photoconductors may develop what is referred to as rub memory if the developer and/or charge rollers remain in contact with them constantly. Rub memory is the build up of a charge onto the surface of a photoconductor, due to constant contact with the rollers. This build up of charge is exhibited in the images formed on media by repeating lines throughout the image. At best, the rub memory dissipates over time, and the repeating lines cease. At worst, however, the rub memory does not dissipate, and the repeating lines do not stop.
The drawings referenced herein form a part of the specification. Features shown in the drawing are meant as illustrative of only some embodiments of the invention, and not of all embodiments of the invention, unless otherwise explicitly indicated.
In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.
As the drum 108 revolves, the printing mechanism 100 shines a laser beam emanating from the laser beam light source 102, and reflected by the reflector 104, onto the surface 106 of the drum 108 to discharge certain points in accordance with an image. In this way, the laser draws, or scans, the image to be printed as a pattern of electrical charges, which can be referred to as an electrostatic image. The drum 108 rotates counter-clockwise, as indicated by the arrow 112. After the pattern has been set, the printing mechanism 100 coats the drum 108 with charged toner, which is a fine powder. The toner also has a positive charge, so the toner clings to the discharged areas of the drum 108, but not to the positively charged background.
The toner is dispensed by a developer roller 114 that rotates clockwise, as indicated by the arrow 116, against the drum 108, after having rotated through the toner hopper 118 to pick up toner. The developer roller 114 is also in contact with the drum 108 during image formation on the media 120 for precise alignment of the image to be formed on the media 120. At other times, during non-use, the developer roller 114 may be separated from the photoconductor drum 108, as will be described. With the powder pattern affixed, the drum 108 rolls over a sheet of media 120, which moves in the direction indicated by the arrow 122. Before the media 120 rolls under the drum 108, it is given a negative charge by the transfer roller 124. This charge is stronger than the charge of the electrostatic image, so the media 120 pulls the powder away from the drum 108. Since it is moving at the same speed as the drum 108, the media 120 picks up the image pattern exactly.
The printing mechanism 100 finally passes the media 120 through the fuser 130, which can be a pair of heated rollers 132 and 134 that move in opposite direction. As the media 120 passes through these rollers 132 and 134, the loose toner powder melts, fusing with the fibers in the media 120. The fuser 130 rolls the media 120 to an output tray, providing a printed page. After depositing the toner on the media 120, the drum 108 passes the discharge lamp. 128, which is a bright light. This exposes the entire photoreceptor surface of the drum 108, erasing its electrical image, so that the process is ready to be repeated.
At least some components of the laser-printing mechanism 100 of
Furthermore, the laser-printing mechanism 100 of
The upper portion 306 has a pin 308 coupled thereto such that a corresponding hole of the lower portion 304 mates with the pin 308 to couple the lower portion 304 to the upper portion 306. That is, the pin 308 is mounted within this hole. The lower portion 304 therefore is capable of pivoting relative to the upper portion 306 about the pin 308, which acts as the pivot point. Most generally, it can be stated that the lower portion 304 and the upper portion 306 are capable of moving relative to each other. Such movement is indicated in
The lower portion 304 of the toner cartridge 300 includes the developer roller 114, such that the roller 114 is situated at the lower portion 304, whereas the upper portion 306 includes the photoconductor drum 108, such that the drum 108 is situated at the upper portion 306. The lower portion 304 may further include other rollers, such as the charge roller 110 of
The lower portion 304 of the toner cartridge 300 includes a guide 310, whereas the upper portion 306 includes a guide 316. The upper portion 306 further includes a slot 312 within which the guide 310 fits so that the lower portion 304 is able to move relative to the upper portion 306. When the toner cartridge 300 is inserted into the printer 200, the guide 316 of the upper portion 306 fits in a path or slot 320 of a sidewall 302 of the printer 200. Fitment of the guide 316 into the slot 320 maintains the upper portion 306 in place, whereas the lower portion 304 is capable of pivoting relative to the upper portion 306.
Furthermore, when the toner cartridge 300 is inserted into the printer 200, the guide 310 is inserted into an upper part 322 of a path of the sidewall 302 of the printer 200. The upper part 322 of the path is connected to a lower part 324 of the path via a transitional part 326 of the path that segues the upper part 322 to the lower part 324. The upper part 322 is parallel but non-collinear with the lower part 324. As the toner cartridge 300 is pushed into the printer 200, the lower portion 304 is forced to pivot counter-clockwise relative to the upper portion 306. This is because the guide 310 of the lower portion 304 moves from the upper part 322, through the transitional part 326, and to the lower part 324 of the path of the printer 200, whereas the upper portion 306 maintains its relative position due to its guide 316 being lodged in the slot 320. Counter-clockwise movement of the lower portion 304 relative to the upper portion 306 causes the roller 114 to contact the photoconductor drum 108.
It can be stated that the path defined by the parts 322, 324, and 326 thereof is receptive to the guide 310 of the toner cartridge 300, and causes the lower portion 304 of the cartridge 300 to move relative to the upper portion 306 of the cartridge 300 upon insertion of the cartridge 300 into the printer 200. The upper part 322 of the path makes initial contact with the guide 310 as the cartridge 300 is inserted into the printer 200, as compared to the other parts 324 and 326 of the path. The upper part 322 of the path further makes last contact with the guide 310 as the cartridge 300 is removed from the printer 200, as compared to the other parts 324 and 326 of the path. The path defined by the parts 322, 324, and 326, thus interacts with the path or slot 320 so that the lower portion 304 of the cartridge 300 moves relative to the upper portion 306 of the cartridge 300 upon removal or insertion of the cartridge 300 into the printer 200.
When the toner cartridge 300 is pulled from the printer 200, the lower portion 304 is conversely forced to pivot clockwise relative to the upper portion 306. This is because the guide 310 of the lower portion 304 moves from the lower part 324, through the transitional part 326, and to the upper part 322 of the path of the printer 200, whereas the upper portion 306 maintains its relative position due to its guide 316 being lodged in the slot 320. Clockwise movement of the lower portion 304 relative to the upper portion 306 causes the roller 114 to separate from the photoconductor drum 108. The printer 200 also includes a cam 328 in
The toner cartridge 300 has a spring or other mechanism, not depicted in
When the lower portion 304 is locked in position relative to the upper portion 306 via the pin 402 mating with the detent 404 in
As has been described, in
Furthermore, as has been described, in
The pin 402 and the detent 404 are one type of locking mechanism that can be employed, and other embodiments of the invention may use other types of locking mechanism. In general, the locking mechanism is such that during shipment of the toner cartridge 300, the forces typically encountered by the cartridge 300 during shipping are insufficient to cause the locking mechanism to unlock, such as the spring-loaded pin to dislodge from the detent 404. As such, when removed from the printer 200, such as during shipping, the cartridge 300 maintains separation of the roller 114 from the photoconductor drum 108, without any additional spacers or other parts.
As has been described in relation to
In
However, movement of the cam 328 to its upright position in
Therefore, movement of the cam 328 from its upright position in
In an embodiment of the invention in which there is no spring or other mechanism to force the lower portion 304 and the upper portion 306 to revert or default to the position in which the roller 114 contacts the drum 108, there may be an additional cam that is positioned over the lower portion 304 of the cartridge 300. Such an additional cam would be used to push the lower portion 304 back downwards so that it moves counter-clockwise relative to the upper portion 306, after the cam 328 has been rotated to its lowered position. That is, two cams may be employed in one embodiment of the invention to cause the lower portion 304 to move clockwise or counter-clockwise relative to the upper portion 306 as desired.
The cam 328 is more generally a mechanism movable between two positions. In one of the positions, it does not contact any portion of the cartridge 300, such as the lower portion 304, so that the roller 114 remains in contact with the photoconductor drum 108. In the other position, the mechanism contacts a portion of the cartridge 300, such as the lower portion 304, so that the roller 114 is separated from the photoconductor drum 108.
The lower part 324 of the path defined by the sidewall 302 of the printer 200 has a larger height than the upper part 322 and the transitional part 326 of the path have. This is so that the guide 310 is able to move upwards within the lower part 324 of the path when the cam 328 is in its upright position in
There is a downwards-extending protrusion 604 on the top surface of the lower part 324 of the path defined by the sidewall 302 of the printer 200, as the lower part 324 segues to the transitional part 326 of the path. Upon removal of the toner cartridge 300 from the printer 200 while the lower portion 304 and the upper portion 306 are in the position depicted in
The lower portion 304 and the upper portion 306 are coupled to one another and are capable of moving relative to each other, such as in the manner as has been described in relation to
The lock mechanism 704 maintains the lower portion 304 and the upper portion 306 in their second position, so that the rollers 702 and the drum 108 are separated from one another. Upon release of the lock mechanism 704, the spring mechanism 706 reverts the lower portion 304 and the upper portion 306 to their first position, so that the rollers 702 and the drum 108 are in contact with one another. The lock mechanism 704 may in one embodiment include a spring-loaded pin 402 and a detent 404, as has been described in relation to
The lower portion guide 310, as has been described in relation to
While the toner cartridge 300 is inserted into the laser printer 200, a cam 328 or other mechanism within the printer 200 may be moved or rotated to again separate the rollers 702 from the photoconductor drum 108 such that they reenter their first position (808). Similarly, while the toner cartridge 300 is inserted into the printer 200, the cam 328 or other mechanism may subsequently be moved or rotated to cause the rollers 702 to again contact the drum 108, in their second position (810). The toner cartridge 300 is ultimately removed from the laser printer 200 (812). As has been described in relation to
It is noted that, although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. For example, embodiments of the invention have been largely described in relation to a printing device that is a laser printer. However, other embodiments of the invention may be implemented in relation to other printers that employ a photoconductor and one or more rollers. In addition, whereas embodiments of the invention have been largely described in relation to a toner cartridge for a laser printer, other embodiments may be implemented in relation to other types of cartridges for other types of printers.
Furthermore, embodiments of the invention have largely been depicted where there is one roller, a developer roller, being in contact with or separated from a photoconductor drum. In other embodiments, however, there may be more than one roller, such as both a developer roller and a charge roller, being in contact with or separated from the photoconductor drum. Furthermore, these rollers may be positioned so that one of them is in contact with the drum while the other is not. For instance, the charge roller may be caused to contact the drum upon insertion of the cartridge into the printer, such that it remains in contact with the drum at all times while the cartridge is inside the printer. Conversely, the developer roller may either be separated from or in contact with the drum while in the printer, by appropriate usage of a cam or other mechanism, as has been described.
This application is thus intended to cover any adaptations or variations of the disclosed embodiments of the present invention. For instance, whereas embodiments of the invention have been described in relation to rollers being separated from the photoconductor, such that there are two states: contact of the rollers with the photoconductor in a first position and separation of the rollers from the photoconductor in a second position, in other embodiments of the invention, there may be more than two such states. For example, in a state “A” two rollers may be in contact with the photoconductor, in a state “B” one roller may be in contact with the photoconductor and the other roller may not be in contact with the photoconductor, and in a state “C” both rollers may not be in contact with the photoconductor. The claims that follow read on this embodiment, because “one or more rollers” can be interpreted in one instance to mean only one of these rollers, such that it is in contact with the photoconductor in a first state “A” and not in contact in a second state “B” (or “C”). The claims can then be interpreted so that “one or more rollers” means that the other roller is in contact with the photoconductor in a first state “A” and not in contact in a second state “C”. That is, “one or more rollers” can be interpreted to mean just one roller, even where there is more than one roller in the cartridge.
It is noted that embodiments of the invention may have contact or no contact between the rollers and the photoconductor in different situations while the cartridge is in the printing device. For instance, during printing at least one of the rollers (or just one of the rollers) may not be in contact with the rollers, in so-called “gap” printing, whereas in another embodiment, at least one of the rollers may be in contact with the photoconductor, in so-called “contact” printing. A control logic within the printing device may thus cause the rollers to individually contact or not contact the photoconductor as needed, based on whether printing is occurring or not, for instance.
Finally, it is noted that separating the rollers from the photoconductor upon removal of the cartridge from a printing device is desirable, because it allows a softer mail to be considered for the rollers, especially the developer roller. A softer developer roller allows less wear and tear on the toner, due to smaller stresses, and this increases developer life. It is manifestly intended that this invention be limited only by the claims and equivalents thereof.
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