JP2752821B2 - Image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus such as a laser printer.

[0002]

2. Description of the Related Art In recent years, laser printers have been widely used as output devices for computers due to their low noise and high image quality. Laser printers generally have a resolution of 300 dpi and a print speed of 10 pages / min. On the other hand, recently, higher image quality of a printer is desired, and a resolution of 600 dpi or more is required.

[0003]

The dot data corresponding to a dot density (print density) of 300 dpi is converted to 600 dpi.
When printing with a printer with a print density of i, 1 in both the vertical and horizontal directions
/ 2. If the number of dots is simply doubled in both the vertical and horizontal directions, the size is not reduced to 1/2, but the jagged outline of the printed character is 30 times.
No improvement is obtained as compared with the case where printing is performed at a printing density of 0 dpi.

[0004] Higher image quality can be achieved by printing bit data corresponding to a printing density of 600 dpi at a printing density of 600 dpi, but the image memory capacity must be quadrupled as compared with a conventional printer having a printing density of 300 dpi. Therefore, not only becomes expensive, but also there is a problem that conventional application software developed for a computer that outputs bit data corresponding to a print density of 300 dpi to a printer cannot be used.

In order to cope with this, an apparatus for printing 300 dpi data at a printing density of 600 dpi is described in US Pat. No. 4,847,641. In this device, when a dot pattern in a character to be printed matches a previously stored pattern, the spot size of the light beam is changed or the dot position is slightly moved (for example, 1/3 dot) in the main scanning direction. Let me. However, this apparatus performs signal processing only in the main scanning direction, so that there is a problem that image quality is not improved in the sub-scanning direction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and converts data corresponding to a low printing density into data corresponding to a high printing density, thereby converting characters such as characters and symbols with high quality image quality. An object of the present invention is to provide an image recording device capable of printing.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image recording apparatus for recording an image by forming dots by pixels for each pixel, comprising an interface section for receiving dot data having a first dot density. On the interface
A dot data having the more accepted first dot density
Interpreter for decoding data, storing font data
Memory unit, and data output from the interpreter unit.
Data and font data stored in the memory
A drawing unit that generates data for drawing by performing
Data having a second dot density
Control means including a conversion unit for converting the
A latent image is formed on the photosensitive drum according to the input dot data.
Image to be formed and output on recording paper containing the optical system
Image forming means, wherein the conversion unit compares the dot pattern of a region of a predetermined size including the pixel of interest with a plurality of stored dot patterns and according to the type of the identified pattern. the image recording apparatus characterized and Turkey be converted into dot data having said second density de <br/> Ttodeta having said first dot density by replacing a dot of the target pixel into a plurality of dots Achieved.

[0008]

[Action] For example, the data of 300dpi of dot density Lee
When input to the interface , the interpreter
Dot data is decoded, and the drawing unit interprets the data.
Data output from the unit and the phone stored in the memory unit
The drawing data is generated by comparison with the drawing data.
The conversion unit compares the dot pattern of an area of a predetermined size including the target pixel of the data output from the drawing unit at the center, for example, an area of 3 rows × 3 columns with a plurality of stored dot patterns. The type of the dot pattern is identified. According to the identification result, the dot of the target pixel located at the center of the area is replaced with, for example, four dots of 2 rows × 2 columns. By executing this operation for all the pixels, the dot data of 300 dpi is converted into the dot data of 600 dpi. Converted by the image forming means.
Latent image is formed on the photosensitive drum according to the dot data
The toner is adhered and fixed, and the image is formed on the recording paper.
Generated and output.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In FIG. 2, reference numeral 10 denotes a laser printer according to the present invention, and reference numeral 30 denotes a host computer. The laser printer 10 includes a controller for processing data output from a host computer, and a base engine for printing characters and symbols on recording paper based on the data processed by the controller. The controller unit includes an interface unit 11 that captures dot data and code data of 300 dpi output from the host computer 30, an interpreter unit 12 that decodes the input dot data and code data, and a data unit and a memory unit that are output from the interpreter unit 12. And a conversion unit 20 for converting data output from the drawing unit 13 into data corresponding to a print density of 600 dpi. You.

The base engine unit includes an optical system 15 for forming a latent image on a photosensitive drum by a laser beam based on data output from the controller unit, a developing unit for attaching toner to the latent image to make it visible, and a residual unit. It comprises a process system 16 including a cleaning unit and the like for removing toner, a fixing system 18 for fixing toner on recording paper, and a paper feeding system 19 for conveying recording paper.

FIG. 1 is a block diagram showing the structure of the conversion unit 20. As shown in FIG.
Line memories 1 to 3 for storing data input via the R gates 21, 22, and 23; a selector 24 for sequentially transferring the contents of the line memory 1 to the line memories 2 and 3; The comparator 25 compares the dot pattern output from the first to third patterns with the pattern stored in the pattern ROM in advance.
A pattern generator 2 for converting a pattern of dot data of dpi into a pattern of dot data of 600 dpi
7, a data selector 28, a selector 24, and a control unit 29 for controlling the data selector 28 for separately outputting the dot data of each row converted to twice the line density into upper and lower rows. FIG. 3 is a time chart showing the timing of the operation of the conversion unit 20. As shown in the figure, every time the horizontal synchronization signal HSYNC is input to the control unit 29 twice, that is, every two scan lines, the SELECT signal is sent from the control unit 29 to the selector 24.
The dot data DI stored in the line memory 1 is sequentially transferred to the line memory 2 and the line memory 3.

The comparator 25 has three rows from the line memories 1-3.
The dot patterns in the three-row area are read, and the read dot patterns are compared with the patterns stored in the pattern ROM to identify the type of the read pattern. As shown in FIG. 4, the pattern generator 27 replaces one dot of the central pixel (pixel of interest) of the area with four dots according to the type of the identified pattern. The pattern generated by the pattern generator 27 is output via the data selector 28 as data for each scan, that is, as image output data D0 corresponding to a print density of 600 dpi.

FIG. 5A shows a printing result of the character "W" by a conventional printer having a printing density of 300 dpi, and FIG. 5B shows a printing result of 300 W by the printer of this embodiment.
This shows the result of converting the dot data of dpi into the dot data of 600 dpi and printing the same character "W".
From these figures, it can be seen that the image quality is greatly improved by converting the dot data of 300 dpi into the dot data of 600 dpi by the above processing.

FIG. 6 shows another example of the configuration of the converter 20.
In the figure, 240 is a selector corresponding to the selector 24 of FIG. 1, 210 is a shift register for storing dots in an area of 9 columns × 7 rows, 220 is a FIFO (first-in first-out memory),
Reference numeral 250 denotes a determination circuit having the functions of the pattern ROM 26, comparison circuit 25, and pattern generator 27 of FIG. 1, reference numeral 280 denotes an output buffer corresponding to the data selector 28 of FIG.
Is a timing control unit corresponding to the control unit 29 of FIG.

In order to convert input data DI corresponding to 300 dpi into data of 600 dpi, 600 dpi is used.
Needs to be adapted to one scan at 300 dpi. For this reason, the image input data DI corresponding to the print density of 300 dpi is written into the FIFO 220 and the shift register 210 through the selector 240 only during the odd line scan among the scans at 600 dpi. During even line scanning, data in the FIFO 220 is repeatedly output. That is, when scanning an even line,
The dot data of one column (a1 to a7) is output to the selector 240 from O220. As a result, the contents of the shift register 210 are updated, and the target pixels are sequentially shifted by one column.

As in the case of FIG. 1, one dot is divided into four dots by a decision circuit 250, and four dot data indicating whether these dots are white or black are output to an output buffer. From 280, the upper two dot data and the lower two dot data are output separately for even-line scanning and odd-line scanning.

FIG. 7 is a diagram showing the contents of data stored in the shift register 210. The dot data a44 of the target pixel is converted by the determination circuit 250 into four dot data c1 to c4 having values corresponding to the contents of the dot data a10 to a88 of the peripheral pixels. As shown in FIG.
2 is dot data of pixels on the left and right sides of the odd line, respectively, and c3 and c4 are dot data of pixels on the right and left sides of the even line, respectively.

FIG. 9 shows a circuit configuration of the determination circuit 250. As shown in the figure, the decision circuit 250 includes coincidence gates A1 to An and OR gates O1 to O4. Shift register 210
The dot data a10 to a88 in the data are matched gates A1 to An
Is input to each of. Each of the coincidence gates has an inverter corresponding to each of the basic patterns on the upper side in FIGS. The dot data representing white is inverted by the inverter and input to the coincidence gate.

FIG. 11 is a conversion pattern corresponding to a basic pattern for oblique line processing, FIG. 12 is a conversion pattern corresponding to a basic pattern for singularity processing, FIG. 13 is a conversion pattern corresponding to a basic pattern for curve processing, FIG. 14 shows a basic pattern for cutting and acute angle processing and a corresponding conversion pattern, and the number of matching gates is equal to the number of basic patterns. If the pattern of the input dot data matches one of the basic patterns, the dot data a
44 is converted into four dot data of a predetermined value and output from one of the coincidence gates. For example, when the input pattern matches the basic pattern unique to the matching gate A1, data c11, c21, c31, and c41 are output from the matching gate A1.

The OR gate O1 outputs data c11, c12,.
The OR of c1n is output as dot data c1, the OR gate O2 outputs the OR of data c21, c22,..., c2n as dot data c2, and the OR gate O3 outputs data c
, C3n are output as dot data c3, and the OR gate O4 outputs data c41, c42,.
Is output as dot data c4. The output buffer 280 stores data c1 to c output from the determination circuit 250.
4 is output to the base engine unit in synchronization with the timing signal shown in FIG. For example, the timing signals VEO and HE
If both O are "1", the divided dot c1 on the left side of the odd line is output.

FIGS. 15 to 18 show the operation of the determination circuit 250 for determining the divided dot data c1 to c4 from the dot data of the peripheral pixels by using logical expressions. In the figure, the symbol * is a logical product, the symbol /
Represents inversion and + represents a logical sum.

[0023]

The image recording apparatus of the present invention exhibits, the image for each pixel
Image recording device that forms and records dots
Then, the dot of the target pixel is replaced with a plurality of dots according to the type of the identified pattern by comparing the dot pattern of the area of a predetermined size including the target pixel with the stored plurality of dot patterns. Therefore, it is configured to convert dot data of low print density into dot data of high print density. Te can improve image quality, also in comparison with the case of performing the smoothing performs operation such becomes simple circuit configuration can increase the processing speed and Do Ri, is recorded at a low print density
Image on recording paper by improving the image quality of
It has the effect that it can be formed .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an example of a conversion unit of a laser printer according to the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of the laser printer of FIG. 1;

FIG. 3 is a time chart of the conversion unit in FIG. 1;

FIG. 4 is an explanatory diagram of a pattern generation operation of the conversion unit in FIG. 1;

FIG. 5 is a diagram showing print results of a conventional printer and a printer according to the present invention.

FIG. 6 is a block diagram showing the configuration of another example of the conversion unit of the laser printer according to the present invention.

FIG. 7 is an explanatory diagram of the contents of a shift register of the conversion unit in FIG. 6;

FIG. 8 is an explanatory diagram of divided dots.

FIG. 9 is a circuit diagram of a determination circuit of the conversion unit in FIG. 6;

FIG. 10 is an explanatory diagram of a timing signal supplied to an output buffer of the conversion unit in FIG. 6;

FIG. 11 is a diagram showing a conversion pattern corresponding to a basic pattern for oblique line processing.

FIG. 12 is a diagram showing conversion patterns corresponding to basic patterns for singularity processing.

FIG. 13 is a diagram showing a conversion pattern corresponding to a basic pattern for curve processing.

FIG. 14 is a diagram showing a conversion pattern corresponding to a basic pattern for cutting and acute angle processing.

15 is a diagram illustrating a logical expression representing an operation of dividing a dot of a target pixel from dot data of a peripheral pixel of the determination circuit in FIG. 9;

16 is a diagram illustrating a logical expression representing an operation of dividing a dot of a target pixel from dot data of a peripheral pixel of the determination circuit of FIG. 9;

17 is a diagram illustrating a logical expression representing an operation of dividing a dot of a target pixel from dot data of a peripheral pixel of the determination circuit of FIG. 9;

18 is a diagram illustrating a logical expression representing an operation of dividing a dot of a target pixel from dot data of a peripheral pixel of the determination circuit of FIG. 9;

[Explanation of symbols]

 10 Laser printer 20 Conversion unit 21-23 OR gate 24 Selector 25 Comparator 26 Pattern ROM 27 Pattern generator 28 Data selector 29 Control unit 210 Shift register 220 FIFO 240 Selector 250 Judgment circuit 280 Output buffer 290 Timing control unit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuriko Kamei 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-64-24568 (JP, A) JP-A-62- 200976 (JP, A) JP-A-55-78670 (JP, A) JP-A-2-65461 (JP, A) JP-A-2-242383 (JP, A) JP-A-63-93269 (JP, A) JP-A-64-86765 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/485 B41J 2/44 B41J 5/30 B41J 21/00 G06F 3/12 H04N 1 / 387 101

Claims (1)

(57) [Claims] 1. An image recording apparatus for forming and recording an image by dots for each pixel, comprising: an interface section for receiving dot data having a first dot density;
The first dot density received by the interface
Interpreter unit for decoding dot data having
Memory for storing print data, the interpreter
Output data and the phone stored in the memory unit
Drawing to compare drawing data with drawing data to generate drawing data
Part, and data output from the drawing part,
Control means including a conversion unit for converting data having density
In response to dot data output from the control means.
Image on recording paper including optical system to form latent image on optical drum
Image forming means for forming and outputting
The conversion unit compares the dot pattern of the area of a predetermined size including the pixel of interest with the stored plurality of dot patterns, and replaces the dot of the pixel of interest with the plurality of dots according to the type of the pattern identified. By the first
Image recording apparatus characterized and Turkey to convert the dot data having a dot density of the dot data having said second density.