Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
2000-08-17
2002-06-18
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S247000
Reexamination Certificate
active
06407765
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image based on image data from an image-forming request source, and more particularly to an image forming apparatus suitable for use in a laser printer or copier which handles image data as a multiplicity of pieces of line data (dot sequences).
2. Description of Related Art
FIG. 14
of the accompanying drawings is a block diagram of a typical image forming apparatus as a common denominator of the conventional art (
20
′) and the subject invention (
20
) described later. The conventional image forming apparatus
20
′, as shown in
FIG. 14
, generally comprises a main control section
2
, an optical unit
3
, a photosensitive body
4
, a processing unit
5
, a paper feed system
6
, a low-voltage power source
7
, and a high-voltage power source
8
. Another element of the conventional image forming apparatus
20
′ is a non-illustrated fixing device.
The conventional image forming apparatus
20
′ is connected to an upper apparatus
1
, such as a personal computer, a host computer or a server, for forming an object image on a sheet of paper or the like (hereinafter also called the paper or the print paper) based on an image-forming request or image data received from the upper apparatus
1
.
The main control section
2
controls operations of the optical unit
3
, the photosensitive body
4
, the processing unit
5
and the paper feed system
6
and also sends the image data, which is received from the upper apparatus
1
, to the optical unit
3
as image information.
The optical unit
3
exposes the photosensitive drum
4
to light to form an electrostatic latent image on the drum surface, including an image processing section described later.
The photosensitive body
4
is in the form of a drum or a belt whose surface is coated with a photosensitive substance (e.g., an optical photoconductor (OPC), organic semiconductor) and is exposed to laser light of LD (Laser Diode, a semiconductor laser
14
in
FIG. 5
) of the optical unit
3
in a pattern corresponding to image data.
The processing unit
5
applies toner to the photosensitive body
4
to develop the latent image on the photosensitive body
4
, transfers the developed image from the photosensitive body to the paper, and clears residual toner off the photosensitive body
4
.
The paper feed system
6
feeds the paper in the conventional image forming apparatus
20
′. The low-voltage power source
7
supplies low-voltage power to various parts or elements, while the high-voltage power source
8
supplies high-voltage power to the photosensitive body
4
and the processing unit
5
.
In the conventional image forming apparatus
20
′, when image data together with an image-forming request is received from the upper apparatus
1
, the photosensitive body
4
is exposed to light by the optical unit
3
based on the received image data, and synchronously with this exposure, feed of the paper is started by the paper feed system
6
.
The processing unit
5
develops a patterned area (electrostatic latent image) on the circumferential surface (hereinafter called the surface) of the photosensitive body
4
, which has a potential as exposed to light, with toner, whereupon the toner image is transferred to the surface of the paper as the paper surface is brought into contact with the surface of the photosensitive body
4
.
Subsequently, the paper feed system
6
feeds the paper, onto which the toner image has been transferred, to the fixing device where the toner image is fixed to complete the forming of an object image on the paper.
FIG. 15
is a block diagram of an image processing section
9
of the conventional image forming apparatus
20
′, illustrating the manner in which an image is formed using a single LD (
1
beam mode).
The image processing section
9
includes, as shown in
FIG. 15
, a buffer section
10
, an image quality control section
11
, a data-transfer controller
12
, a data-readout controller
13
, and an LD
14
. The image processing section
9
produces a video signal (pulse signal) to turn on/off the LD
14
based on the image data received from the upper apparatus
1
so that the LD
14
emits laser light in response to the pulse signal to expose the photosensitive body
4
.
Here the image data received from the upper apparatus
1
contains a multiplicity of pieces of line data representing the object image, line data of each piece corresponding to a dot sequence of an individual line of the object image and including image information of the individual dots composing the dot sequence.
The LD
14
irradiates a laser beam on the surface of the photosensitive body
4
to form an electrostatic latent image there under the control of the image quality control section
11
in such a way that dot sequences corresponding to a plurality of pieces of line data contained in the image data are formed on the photosensitive body
4
.
The image quality control section
11
extends the image data over a memory (not shown) and makes scanning using a matrix (at
100
in FIGS.
16
-
19
). At that time the image quality control section
11
determines an actual-image-forming state of an individual dot, for every dot to be formed by the LD
14
, based on the regional image information of that individual dot contained in the image data and the regional image information of other dots adjacent to that individual dot, and produces a pulse signal having a pulse width corresponding to the determined actual-image-forming state for outputting to the LD
14
, thereby controlling the quality of the object image to be formed.
The buffer section
10
is disposed between the upper apparatus
1
and the image quality control section
11
for temporarily retaining the image data from the upper apparatus
1
and is composed of a predetermined number (
4
in
FIG. 15
) of line-data buffers
10
-
1
through
10
-
4
each for storing line data of a single line of the image data received from the upper apparatus
1
.
The data-transfer controller
12
stores a plurality of pieces of line data, which are contained in the image data from the upper apparatus
1
. And the data-readout controller
13
reads the line data, which is stored in the line-data buffers
10
-
1
through
10
-
4
of the buffer section
10
by the data-transfer controller
12
, into the image quality-control section
11
.
The data store operation by the data-transfer controller
12
and the data readout operation by the data-readout controller
13
take place roughly at the same time.
FIG. 16
, (a) through (c), show the line data needed when the image quality is controlled by the image quality control section
11
in the 1-beam mode.
For forming the image of a particular dot A, the image quality control section
11
determines an actual-image-forming state of the dot A based on the image information of dots of 5 (lines)×7 (sequences) about the dot A, as described later in connection with
FIGS. 17 through 19
. Specifically, an actual-image-forming state of an individual dot on the central line is determined as the line data of 5 lines extended over a memory (not shown) of the image quality control section
11
is scanned using a matrix
100
of 5 lines×7 sequences.
For making image forming in the 1-beam mode, the image data (line data) read out from the buffer section
10
by the data-readout controller
13
is inputted to the image quality control section
11
one line after another. And to determine an actual-image-forming state of each dot of line data of the 1st line partially composing the object image, as shown in (a) of
FIG. 16
, scanning is performed using the matrix
100
after inputting and extending the first three lines of line data L
1
-L
3
. Then, as shown in (b) of
FIG. 16
, an actual-image-forming state of each dot of the line data L
2
is determined while the 4th line of line data L
4
is inputted and extended to be scanned using the matrix
100
, whereupon, as shown in (c) of
FIG.
Armstrong Westerman & Hattori, LLP
Fujitsu Limited
Pham Hai
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