JP2749604B2 - Image processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Field of Industrial Application) The present invention relates to an image recording apparatus for recording an image by scanning a surface of a photoreceptor with a laser beam in an electrophotographic recording apparatus.

(Prior Art) Generally, in an image recording technique by laser beam scanning, the size, shape, output, etc. of the spot of the laser beam have a great influence on the stability of image quality. Further, laser beam image recording apparatuses based on electrophotography include an image exposure method (IAE method) for exposing an image portion and a background exposure method (BAE method) for exposing a non-image portion.

(Problems to be Solved by the Invention) However, according to the IAE method, as the laser spot diameter increases, the line width of characters and lines becomes thicker. In the BAE method, as shown in part B of FIG. 5 (B), as the laser spot diameter increases, the line widths of characters and lines become thinner and faded. If the beam diameter is small, black streak-like noise is generated in the main scanning direction (line direction), as shown in part A of FIG. H is a sub-scanning width in the rotation direction of the rotary drum 1 (FIG. 1). Therefore, the laser beam image recording apparatus needs to determine an appropriate beam diameter independently for the IAE method and the BAE method. Especially,
In the BAE method, in order to prevent black streaks, characters were not thinned and the spot diameter was more strictly controlled than in the IAE method.

In view of the above, the present invention effectively solves the problems of the prior art, has a relatively simple configuration, and has an increased degree of freedom in laser spot diameter for image recording by laser beam scanning, thereby selecting a diameter. Easy, and without black streaks,
It is another object of the present invention to provide an image processing apparatus in which characters are not thinned.

(Means for Solving the Problems) In order to achieve such an object, the present invention provides an image processing apparatus that records image data by scanning the surface of a photoreceptor with a laser beam. An image data memory unit for sequentially storing each line, a first-in first-out memory unit capable of sequentially storing the next line of the image data, and a line for the image data memory unit and a next-first-in first-out memory unit An operation unit for performing an operation of comparing the image data with the line data, a first input means for storing one line of image data in the image data memory unit, and a second input means for storing the operation result data of the operation unit A third input means for holding image data in the first-in first-out memory unit; and an image data for two lines by repeatedly switching each data of the first to third input means line by line. A modulator that performs three laser scans on the laser beam and adjusts on / off of the laser beam.

(Operation) By such technical means, the image data which repeats on / off of the laser beam for each line is relatively simple even by the BAE method, and the laser spot diameter of the image recording by the laser beam scanning is relatively simple. Is obtained, and an image is obtained in which lines are not thinned or blurred, and black streak-like noise between lines is not generated.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image processing apparatus in which the present invention is implemented, and FIG. 2 is a circuit configuration diagram of an embodiment of the present invention. 1 and 2, an image processing apparatus 20 mainly includes a photosensitive drum 1, a beam position detecting mirror 2, a horizontal synchronizing signal generator 3, an fθ lens 4, a polygon mirror 5, a collimator 6, and a semiconductor laser 7. Is done.

Reference numeral 8 denotes an image data memory unit, 9 denotes a first-in first-out (FIFO) memory unit in this embodiment,
A first-in first-out memory unit capable of storing certain image data for one scanning line. In this embodiment, an operation unit 10 performs a logical OR operation of inputs. In this embodiment, 11 to 13 read and hold image data in this embodiment. (Latch) a first data latch unit
Reference numeral 14 denotes a laser modulator, and reference numeral 15 denotes a timing signal generator.

Next, FIG. 3 shows a waveform diagram of an output signal of the timing signal generator of FIG. 2, (A) is a clock signal waveform output in synchronization with a horizontal synchronizing signal, and (B) is a delay of (A). It is a partial enlarged view which displays a signal. In the figure, a hatched portion indicates an ON state, and a timing signal a is a horizontal synchronization signal transmitted from the horizontal synchronization signal generator 3, and timing signals c, e, f, and g.
Is a signal that is synchronous with the timing signals b and d but slightly delayed by the timing s.

The timing signal b is a signal for outputting image data from the image data memory unit 8 in the later-described faces 1 and 2. The timing signal c is a signal for taking the image data of the faces 1 and 2 into the first-in first-out (FIFO) memory unit 9. The timing signal d includes the image data output from the image data memory unit 8 in the phase 2,
It is a signal for performing a comparison operation of data with the image data of one line before recorded in the first-in first-out memory unit 9 in advance.

The timing signal e is a print timing signal for operating the laser in the phase 1. The timing signal f is a timing signal for printing the logical sum data at the timing d in the face 2. The timing signal g is a print timing signal for the face 3 described later.

The operation function of the image processing device 20 configured as described above will be described.

When the image writing operation is started (printing start), the timing signal generator 15 outputs an image output timing signal b.
And outputs the image data of the first line from the image data memory unit 8. Further, a timing signal c slightly delayed from the timing signal b is output, and the image data is captured and recorded in the first-in first-out memory unit 9. at the same time,
The data latch 11 is turned on by the timing signal e, and the image data is input to the laser modulator 14. This operation is called phase 1.

Similarly, the image data of the second line is output from the image data memory unit 8 by the timing signal b, and the image data is captured and recorded in the first-in first-out memory unit 9 by the timing signal c. At the same time, the timing signal b
With the timing signal d output at the same timing as
The image data in the first-in first-out memory unit 9 is used by the logical sum operation unit 10
Is input to The logical sum operation unit 10 performs a logical sum operation on the image data on the first line from the first-in first-out memory unit 9 and the image data on the second line from the image memory unit 8 and outputs the operation result. I do. At this time, the data latch unit 12 is turned on by the timing signal f, and this image data is input to the laser modulator 14. This operation is referred to as face 2.

Next, the image data of the second line of the first-in first-out memory unit 9 is output by the timing signal d. At the same time, the data latch unit 13 is turned on by the timing signal g, and this image data is input to the laser modulator 14.
This operation is called phase 3.

In this way, the operations of the faces 1, 2, and 3 are repeated, and three laser scans are performed on the image data of two lines.

That is, such image data is sequentially stored in the image data memory unit 8 for each line, the next line of the image data is sequentially stored in the first-in first-out memory unit 9, and one line of the image data memory unit 8 is stored. The arithmetic unit 10 performs a comparison operation on the image data of the next line of the first-in first-out memory unit 9 and the image data of one line of the image data memory unit 8 by the first data latch unit 11. The operation result data of the unit 10 is held by the second data latch unit 12, the image data of the first-in first-out memory unit 9 is held by the third data latch unit 13, and the first to third data latch units 11, 12, 13 Is repeatedly switched for each line, and laser scanning is performed three times on image data for two lines to turn on / off the laser beam.
The image processing is performed by adjusting the OFF with the modulator 14.

Next, FIG. 4 shows a laser output pattern diagram of the image processing apparatus according to the present invention, wherein (A) shows a laser on / off state for each line, and (B) shows a laser on / off state different from (A).
It is the case of off. In the figure, the white circle indicates the logic of the image data with an O mark, the black circle indicates the logic of 1, and the BAE
In the method, the portion irradiated with the laser becomes white. Therefore, when the input is zero, the laser is turned on and the laser modulator 14 emits light.

Α, β, and γ correspond to phases 1, 2, and 3 shown in FIG. 3, a and b correspond to the image data of the first and second lines, and laser O corresponds to data O. doing.
Note that α corresponds to the data a, β corresponds to the logical sum of the data a and b, and γ corresponds to the data b.

The laser scanning pattern formed by such processing does not cause thinning or blurring of the line even by the BAE method for image data in which laser on / off operation is repeated for each line as shown in FIG. Further, no black streak-like noise occurs between the lines as shown in FIG. Thus, the processing state of the image data is improved.

As in the conventional case, the feed in the sub-scanning direction is realized by rotating the photosensitive drum 1 at a constant speed in accordance with the printing interval of the main scanning. Therefore, the rotation speed of the photosensitive drum 1 is set to 2/3 times so that the printing density becomes 3/2 times the sub-scanning direction.

In the present embodiment, the image processing apparatus which operates so that the laser is turned on when the image data is O is shown.
Is changed from the logical sum operation to the logical product operation, an image processing apparatus that operates so that the laser is turned on when the image data is 1 can be configured.

(Effects of the Invention) As described above, according to the present invention, image data is sequentially stored in the image data memory unit for each line, and the next line of the image data is sequentially stored in the first-in first-out memory unit. The arithmetic unit compares the image data of one line of the image data memory unit with the next line of the first-in first-out memory unit, and stores the image data of one line of the image data memory unit in the first data latch unit. , The operation result data of the operation unit is held in the second data latch unit, and the image data of the first-in first-out memory unit is held in the third data latch unit.
In the prior art, the data of the third data latch unit is repeatedly switched for each line, laser scanning is performed three times for image data of two lines, and the on / off of the laser beam is adjusted by a modulator. The problem is effectively solved, the structure is relatively simple, the degree of freedom of the laser spot diameter for image recording by laser beam scanning is expanded, the diameter can be easily selected, and no black streaks are generated, and letters are not generated. This produces an effect that an image without thinning and blurring can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image processing apparatus in which the present invention is implemented, FIG. 2 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 3 is a waveform diagram of an output signal of a timing generator. FIG. 4A is a clock signal waveform output in synchronization with the horizontal synchronizing signal, FIG. 4B is a partially enlarged view showing the delay signal of FIG. 4A, and FIG. 4 is an image processing apparatus according to the present invention. 5A shows a laser output pattern diagram, FIG. 5A shows a case of laser on / off for each line, FIG. 5B shows a case of laser on / off different from FIG. 5A, and FIG. FIG. 8A shows a case where the laser spot diameter is small, and FIG. 8B9 shows a case where the laser spot diameter is large. 8: Image data memory section, 9: FIFO memory section, 10: OR operation section, 11 :, 12, 13: Data latch section, 14: Laser modulator, 1
5: Timing signal generator, 20: Image processing device.

Claims (1)

(57) [Claims] An image processing apparatus for recording image data by scanning a surface of a photoreceptor with a laser beam,
An image data memory unit for sequentially storing the image data line by line; a first-in first-out memory unit capable of sequentially storing the next line of the image data; a one-line first-in first-out unit of the image data memory unit An arithmetic unit for performing a comparison operation of the image data with the next line of the memory unit, and a first unit for holding the image data for one line of the image data memory unit
An input unit, a second input unit for storing operation result data of the operation unit, a third input unit for storing image data of the first-in first-out memory unit, and data of the first to third input units. An image processing apparatus, comprising: a modulator that performs laser scanning three times on image data for two lines by repeatedly switching each line, and adjusts on / off of the laser beam.