Patent Grant
7805099
This application is related to U.S. application Ser. No. 11/960,258 entitled “CARRIER REPLENISHMENT AND IMAGE MOTTLE REDUCTION SYSTEM” and U.S. application Ser. No 11/960,330 entitled “A TONER IMAGE REPRODUCTION MACHINE INCLUDING A BALL VALVE DEVICE HAVING A PRESSURE RELEASE ASSEMBLY” both filed on the same date herewith, and having at least one common inventor.
The present disclosure relates generally to toner image reproduction machines, and more particularly, concerns such a machine having a carrier replenishment system including a teeter-totter valve for a carrier replenishment system.
In a typical toner image reproduction machine, for example an electrostatographic printing process machine contained within a single enclosing frame, an imaging region of a toner image bearing member such as a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is irradiated or exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document.
After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed at a development station by bringing a developer material in a developer housing into contact therewith. Generally, the developer material comprises magnetic carrier particles and toner particles that adhere triboelectrically to carrier particles. During development, the toner particles are attracted from the carrier particles to the latent image thereby forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are then heated by a fusing apparatus within the single enclosed frame to permanently affix the powder image to the copy sheet.
Toner particles in the developer material in the developer housing accordingly become more and more depleted during image development as described above, ordinarily resulting in diminishing image quality. To maintain image quality, fresh toner particles therefore must be regularly added to the development. It has also been found that image quality can further be improved by regularly also adding fresh carrier particles to the developer housing, for example, using a carrier replenishment system.
In accordance with the present disclosure, there has been provided a teeter-totter valve device for metering magnetic particles from a hopper that includes (i) a tube connected to the hopper for flow of magnetic particles out of the hopper; (ii) a teeter-totter member having a first arm including a first distal end, and a second adjustable arm including a second distal end; (iii) a support assembly supporting the teeter-totter member on and spaced from the tube; (iv) a first magnet located at the first distal end; (v) a second magnet located at the second distal; and (vi) a moving assembly for moving each of the first magnet and the second magnet towards and away from a first near point and a second near point on the tube to create or remove a point magnetic field and magnetic particles dam within the tube, thereby stopping or allowing flow of a desired quantity of magnetic particles past the first near point and past the second near point.
The foregoing and other features of the instant disclosure will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawing in that:
Referring first to the
Initially, a portion of the photoconductive belt surface passes through charging station AA. At charging station AA, a charging wire of a corona-generating device indicated generally by the reference numeral 22 charges the photoconductive belt 10 to a relatively high, substantially uniform potential.
As also shown the reproduction machine 8 includes a controller or electronic control subsystem (ESS) 29 that is preferably a self-contained, dedicated minicomputer having a central processor unit (CPU), electronic storage, and a display or user interface (UI). The ESS 29, with the help of sensors and connections, can read, capture, prepare and process image data and machine component status information to be used for controlling operation of each such machine component.
Still referring to the
ROS 30 includes a laser with rotating polygon mirror blocks. Preferably a nine-facet polygon is used. At exposure station BB, the ROS 30 illuminates the charged portion on the surface of photoconductive belt 10 at a resolution of about 300 or more pixels per inch. The ROS will expose the photoconductive belt 10 to record an electrostatic latent image thereon corresponding to the continuous tone image received from ESS 29. As an alternative, ROS 30 may employ a linear array of light emitting diodes (LEDs) arranged to illuminate the charged portion of photoconductive belt 10 on a raster-by-raster basis.
After the electrostatic latent image has been recorded on photoconductive surface 12, belt 10 advances the latent image through development stations CC, that include four developer housings 15A, 15B, 15C, 15D as shown, containing developer material, for example two-component developer material consisting of charged magnetic carrier particles and tribo-electrically charged CMYK color toner particles, one color per developer housing. At each developer housing 15A, 15B, 15C, 15D the charged toner particles contained in the developer material that is in-use are appropriately attracted electrostatically to, and develop the latent image.
As pointed out above, in-use developer material (that is, the mix of carrier and toner particles) in each developer housing typically becomes depleted of toner particles over time as toner particles are attracted to, and develop more and more images. This is one cause of poor image quality. Fresh toner particles hence have to be frequently and controllably added to the developer housing. Another cause of poor image quality has been found to be aging carrier—a problem addressed by the carrier replenishment apparatus and teeter-totter valve of the present disclosure (described in detail below).
With continued reference to
The fuser assembly 70 for example, includes a heated fuser roller 72 and a pressure roller 74 with the powder image on the copy sheet contacting fuser roller 72. The pressure roller is crammed against the fuser roller to provide the necessary pressure to fix the toner powder image to the copy sheet. The fuser roller 72 is internally heated by a quartz lamp (not shown).
The sheet 48 then passes through fuser assembly 70 where the image is permanently fixed or fused to the sheet. After passing through fuser 70, a gate 88 either allows the sheet to move directly via output 17 to a finisher or stacker, or deflects the sheet into the duplex path 101. Specifically, the sheet (when being directed into the duplex path 101), is first passed through a gate 134 into a single sheet inverter 82. That is, if the second sheet is either a simplex sheet, or a completed duplexed sheet having both side one and side two images formed thereon, the sheet will be conveyed via gate 88 directly to output 17. However, if the sheet is being duplexed and is then only printed with a side one image, the gate 88 will be positioned to deflect that sheet into the inverter 82 and into the duplex loop path 101, where that sheet will be inverted and then fed to acceleration nip 102 and belt transports 110, for recirculation back through transfer station DD and fuser 70 for receiving and permanently fixing the side two image to the backside of that duplex sheet, before it exits via exit path 17.
After the print sheet is separated from photoconductive surface 12 of belt 10, the residual toner/developer and paper fiber particles still on and may be adhering to photoconductive surface 12 are then removed therefrom by a cleaning apparatus 112 at cleaning station EE.
Still referring to
Referring now to
As further shown, in accordance with the system 200, the carrier-only hopper 210 includes level sensors S1 and S2, as well a pressure sensor S3 being monitored by controller 29 and a system program 29P. The hopper 210 as such needs to be maintained at the same air pressure as the valves and transport tubes in order to eliminate any pressure drop across the metering valves. This is because the metering valves work by gravity and so are sensitive to any differential air pressure across them. Additionally, the hopper cannot be vented at any time to atmospheric pressure because that will create a pressure difference across the metering valves and thus block the gravitational flow of carrier through the valves.
Referring now to
Accordingly, the electrostatographic image reproduction machine 8 includes (a) a moveable imaging member 10 including an imaging surface 12; (b) imaging means 20, 30 for forming a latent image on the imaging surface; and (c) a toner development station CC that includes (i) developer housings 15A, 15B, 15C, 15D each containing in-use two-component developer material of toner particles and magnetic carrier particles for developing the latent images; (ii) a carrier replenishment system 200 including a carrier-only hopper 210 containing magnetic carrier particles and an air blower 240 for adding fresh magnetic carrier particles to the developer housings; and (iii) a teeter-totter valve or valve assembly 400 for metering the fresh magnetic carrier particles from the carrier-only hopper into the replenishment system.
More specifically as illustrated in
The controller 29 is provided with a program 29P, pf (
As shown, each tube 410 and its longitudinal axis 412 are located vertically in order to allow gravitational flow of magnetic particles from the hopper. From the support point, the first arm portion has a first, fixed length L1 to the first distal end, and the arm portion has a second, adjustable length L2 to the second distal end.
In one embodiment, as shown in
In another embodiment, as shown in
As further shown more fully in
Depending on replenishment system requirements, the second, adjustable length L2 of the second arm portion can similarly also be adjusted to be shorter than the first, fixed length L1 of the first arm portion with a second near point P2′ as shown. When then operated as described above, with a top, second magnetic field and dam at D2′ formed at the second near point P2′, a relatively smaller quantity Q2 of carrier particles will flow past the first near point P1 into the replenishment system.
As further illustrated, depending again on replenishment system requirements, the second, adjustable length L2 of the second arm portion can similarly also be adjusted to be longer than the first, fixed length L1 of the first arm portion with a second near point P2″, as shown. When operated as described above, with a top, second magnetic field and dam at D2″ formed at the second near point P2″, a relatively larger quantity Q3 of carrier particles will flow past the first near point P1 into the replenishment system.
Accordingly, in the first embodiment as shown in
In order to release or meter a desired quantity Q1, Q2, Q3 of the magnetic carrier particles in the tube as such, the solenoid S6 (and moving means 434, 436) is actuated to move (for example swing) the lower, first magnet 430 away from the first near point P1 while at the same time also similarly moving the top, second magnet 432 against the tube 410 at the second near point P2, P2′, P2″. Doing so creates a top magnetic field and dam D2, D2′, D2″ at the second near point P2, P2′, P2″, thereby stopping any flow of magnetic carrier from the hopper past the top magnetic field and dam D2, D2′, D2″, and at the same time thereby allowing all magnetic carrier particles between (i) the upper, second near point P2, P2′, P2″ (now dammed) and (ii) the lower, first near point P1 (now opened with no lower magnetic field and dam D1) to flow past the lower, first near point P1 as a metered quantity Q1, Q2, Q3 of such carrier particles.
Although the metered quantity Q1, Q2, Q3 of such carrier particles as described can be varied by adjusting the length of the second arm portion L2, it should be understood that such quantity Q1, Q2, Q3 of such carrier particles can also be effectively varied by means of the frequency program pf.
As can be seen, there has been provided a teeter-totter valve device for metering magnetic particles from a hopper that includes (i) a tube connected to the hopper for flow of magnetic particles out of the hopper; (ii) a teeter-totter member having a first arm including a first distal end, and a second adjustable arm including a second distal end; (iii) a support assembly supporting the teeter-totter member on and spaced from the tube; (iv) a first magnet located at the first distal end; (v) a second magnet located at the second distal; and (vi) a moving assembly for moving each of the first magnet and the second magnet towards and away from a first near point and a second near point on the tube to create or remove a point magnetic field and magnetic particles dam within the tube, thereby stopping or allowing flow of a desired quantity of magnetic particles past the first near point and past the second near point.
It will be appreciated that various of the above-disclosed and other features and functions of this embodiment, or alternatives thereof, may be desirably combined into other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3717122 | Hudson | Feb 1973 | A |
| 4463502 | Fitzgerald et al. | Aug 1984 | A |
| 5095338 | Hayes, Jr. et al. | Mar 1992 | A |
| 5685348 | Wegman et al. | Nov 1997 | A |
| Number | Date | Country | |
|---|---|---|---|
| 20090162105 A1 | Jun 2009 | US |
