Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1998-02-17
2001-01-30
Lee, Susan S. Y. (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S235000
Reexamination Certificate
active
06181357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to data processing systems and, in particular, to electrophotographic reproduction devices. Still more particularly, the present invention relates to the adjustment of the timing of a scanning laser beam with respect to a second scanning laser beam in an electrophotographic reproduction device utilizing a plurality of scanning laser beams in order to adjust the timing of a plurality of PEL clocks.
2. Description of the Related Art
Electrophotographic reproduction devices can generally be divided into copiers or printers. The present invention relates primarily to printers.
In an electrophotographic printer, a charged photoconductor is selectively discharged by the operation of a print or imaging station, to provide an electrostatic latent image on the photoconductor's surface. This latent image corresponds to the visual image that is to be printed, first by applying toner to the photoconductor, and then by transferring the toner image to the surface of substrate material such as a sheet of plain paper.
Electrophotographic reproduction devices may be constructed to apply toner to either the photoconductor's discharged area, or to the photoconductor's charged area. The former type of device is called a discharged area developing device, whereas the latter device is called a charged area developing device.
The broad spirit and scope of the invention are not to be limited to a scanning light beam since, as will be appreciated by those of skill in the art, such a scanning beam generally comprises a moving point or spot of light, that can be modulated in intensity—for example, on and off, to form an electrostatic latent image on the photoconductor.
Thus, the term, scanning laser beam, as used herein, is intended to mean any moving point of light to which the photoconductor is sensitive, and which operates to sequentially print the small picture elements, or PELs, of one or more image rows, as the point of light sequentially scans the photoconductor, image row after image row.
In printers of this type, the image to be printed comprises an electronic image signal that may, for example, reside in the page memory of a data processing system. In this page memory, each photoconductor PEL area that is to be discharged may, again by way of example, be represented by a binary “1”, in which case each PEL this is to be left in its charged state would be represented by a binary “0”. As the spot of light moves across a photoconductor PEL row, the row content of the page memory signal is gated utilizing a PEL clock to control or modulate the spot of light in accurate synchronism with the position of the moving spot of light.
The art has recognized the need to synchronize the gating of the print data signal to laser beam modulator means as a function of the beam's position prior to each photoconductor scan. For example, it is known to use a photosensor that is located on an image plane that is established by the physical location of the photoconductor. As a result of the detection of the laser beam at this start of scan position, a timing pulse, or beam detection indicator, is generated to start the flow of print data to a beam modulator.
Imaging stations used in electrophotographic printers often utilize more than one scanning laser beam. In systems utilizing two beams, for example, each beam scans a different PEL row approximately concurrently so that two PEL rows are simultaneously scanned. Therefore, two beam detection indicators are generated, one for each beam. A fixed time offset between a first pel of a first beam and a first pel of a second beam may be equivalent to an offset of several tens of pels on order to avoid interference between the adjacent beams.
Therefore a need exists for a method and system in an electrophotographic reproduction devices which utilizes a plurality of scanning laser beams for adjusting the timing of a first scanning laser beam with respect to a second scanning laser beam, and therefore the timing of a plurality of PEL clocks, so that the associated PELs are approximately aligned.
SUMMARY OF THE INVENTION
It is therefore one object of the present invention to provide an improved data processing system.
It is another object of the present invention to provide an improved electrophotographic reproduction device.
It is yet another object of the present invention to provide a method and system in an electrophotographic reproduction devices which utilizes a plurality of scanning laser beams for the adjustment of the timing of a first scanning laser beam utilizing a first PEL clock with respect to a second scanning laser beam utilizing a second PEL clock.
The foregoing objects are achieved as is now described. A method and system are disclosed for the modification of the timing of one of a plurality of PEL clocks included within an electrophotographic device. A first indicator is generated which is associated with a first position on a print receiving material. A second indicator is generated which is associated with a second position on the print receiving material. A first enable signal is generated for initiating a first scan. The first scan is executed utilizing a first laser beam synchronized by a first PEL clock. A second enable signal is generated for initiating a second scan. The second scan is executed utilizing a second laser beam synchronized by a second PEL clock. The first and second scans are executed approximately concurrently. An offset of the second position from the first position is determined. The timing of a second PEL clock is modified by adjusting the second enable signal utilizing the offset so that the first and second positions are approximately aligned.
The above, as well as additional objectives, features, and advantages of the present invention, will become apparent in the following detailed written description.
REFERENCES:
patent: 4598283 (1986-07-01), Tung et al.
patent: 4654721 (1987-03-01), Goertzel et al.
patent: 4725892 (1988-02-01), Suzuki et al.
patent: 4928118 (1990-05-01), Leksell et al.
patent: 4962431 (1990-10-01), Imakawa et al.
patent: 4970604 (1990-11-01), Coueignoux
patent: 4977411 (1990-12-01), Pepe
patent: 5029107 (1991-07-01), Lee
patent: 5081477 (1992-01-01), Gibson
patent: 5113494 (1992-05-01), Menendez et al.
patent: 5115256 (1992-05-01), Miyagi et al.
patent: 5170261 (1992-12-01), Cargill et al.
patent: 5221971 (1993-06-01), Allen et al.
patent: 5235432 (1993-08-01), Creedon et al.
patent: 5278586 (1994-01-01), Yoneda et al.
patent: 5506698 (1996-04-01), Nishihara
Felsman Bradley Vaden Gunter & Dillon, LLP
International Business Machines - Corporation
Lee Susan S. Y.
Ngo Hoang
Strimaitis Ray
LandOfFree
Method and system for the modification of the timing of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for the modification of the timing of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for the modification of the timing of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2517443