JP2002369008A - Binary image data processing method and image forming apparatus using the same - Google Patents

Abstract

(57) [Summary] (Corrected) [PROBLEMS] To provide binary image data capable of performing high-speed and clear image formation in an image forming apparatus such as an LED printer in which pixel forming elements are fixedly arranged in a main scanning direction. Provide a processing method. An image forming apparatus includes a recording head having a plurality of pixel forming elements arranged in a main scanning direction, and drives each pixel forming element of the recording head based on binary image data to form a desired image. In a method of processing binary image data applied to a forming apparatus, input binary original image data is recognized by a pattern of an n × n or n × m (n, m is the number of bits) lattice matrix, This pattern is compared with a plurality of discrimination patterns stored in advance, and interpolated image data of pixels of dots smaller than the pixels of the original image is generated in accordance with the discrimination pattern that matches the pattern. Are alternately output by the recording head in a 1/2 line cycle to perform a smoothing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing binary image data which can be used in a computer output printer for forming a visible image based on digital image data, a digital copying machine, and the like. A recording head in which a plurality of pixel forming elements are arranged in a main scanning direction with respect to an image forming body that can move in a moving direction, and each pixel forming element of the recording head is driven based on input binary image data. The present invention is applicable to an image forming apparatus configured to form a desired image by performing
The present invention relates to a method of processing value image data.

Further, even when the input binary image data includes a dither image area, the dither image area can be efficiently determined and the smoothing processing can be performed without impairing the dither processing. The present invention relates to a method of processing value image data.

Further, as a light source for image writing, LE
The present invention relates to a digital image forming apparatus that forms a clear image by using a recording head in which a plurality of fixed pixel forming elements such as D are arranged in the main scanning direction and utilizing the above-described image data processing method.

[0004]

2. Description of the Related Art With the rapid development of computer networks and the like, image forming apparatuses for forming visible images from digital image data, such as laser printers, LED printers, ink jet printers, thermal printers, and multifunctional digital copiers, are easy to use. In order to improve the image quality, higher speed image data processing and higher definition image formation are demanded more than ever before.

Conventionally, image processing methods such as a dither method, a density pattern method, and a smoothing method have been known in order to obtain a clear image, and these processing methods and other processing methods are selectively used or combined. By doing so, good image formation is possible.

[0006] Among these processes, the smoothing process will be described. The above-mentioned printer temporarily stores one page of image data sent from a host device such as a host computer in a page memory, and then stores the image data in a page memory. The image data stored in the page memory is read out in line order and printed, but if the read data is printed as it is, a jagged outline called jaggy is formed in the image due to the step of the pattern between adjacent pixels. For this reason, an interpolated pixel is generated between pixel pitches in the main scanning direction, that is, between one pixel-to-pixel pitch, thereby providing a smooth image with less jaggies. Normally,
When reading the image data from the page memory, the image data is recognized as an n × n or n × m matrix pattern, and this pattern is compared with a plurality of discrimination patterns stored in advance to perform recognition. An interpolated pixel is generated based on a discrimination pattern that matches the extracted pattern. Normally, the interpolation pixel has a size smaller than that of the pixel of the original image, and is interpolated at a step between the original pixel and the original pixel.

In a laser printer, for example, such a small interpolation pixel can be generated by controlling the lighting time (pulse width in the main scanning direction) of the laser beam for each pixel. The object is achieved by irradiating a pixel having a half diameter or a half width onto the image forming body. FIG. 14 shows an example of a pattern of original pixels of a 3 × 3 dot matrix to be smoothed in a laser printer. It is understood that the portion indicated by black filling is the original pixel portion of the black character, and has a step between adjacent pixel columns. FIG.
A black interpolated pixel (indicated by a hatched portion in the figure) having a width half the width of the original pixel is formed between the original pixels in the main scanning direction of the pattern No. 3 and smoothing processing is performed. It is an example. Thus, in a device such as a laser printer that can adjust the image pitch in the main scanning direction, the smoothing process can be easily performed by adjusting the pixel pitch in the main scanning direction.

[0008]

On the other hand, unlike a laser printer or the like which can adjust the pixel pitch in the main scanning direction,
In LED printers and plotters in which the pixel pitch in the main scanning direction is fixed, a large number of LEDs are fixedly cascaded in the main scanning direction at a fixed pitch, and the LEDs are simultaneously turned on. It is difficult to form an interpolation pixel by lighting a small diameter spot at
The method of forming an interpolated pixel between pixel pitches as described in “06” is not suitable.

Furthermore, in performing the above-described smoothing processing, sufficient consideration has not been given to the competition between different processings for image data that has been subjected to processing such as dithering in advance.

[0010] Further, the conventional printer as described above,
When a page memory of at least one page capacity is required, or when image data is stored in a compressed state in order to use the page memory efficiently, a bit map is developed using a band buffer or the like at the time of reading. However, there are disadvantages in that the apparatus and control are complicated, such as performing processing, and the cost is high.

On the other hand, printers called host-based printers or dumb printers are known. These printers do not store image data input from the outside in a page memory in the printer or develop a bitmap, but develop a bitmap in a host device such as a host computer before inputting the data to the printer. Although the configuration is such that the received image data is received, the processing inside the printer can be simplified and the printing can be performed promptly without delay, but the processing for performing processing such as smoothing on the received image data is not sufficient.

Therefore, the present invention firstly adopts L as described above.
It is an object of the present invention to provide a method of processing binary image data capable of performing high-speed and clear image formation in an image forming apparatus such as an ED printer in which pixel forming elements are fixedly arranged in a main scanning direction.

Another object of the present invention is to provide a method for effectively discriminating between an image area which has been subjected to dither processing and an image area to be subjected to smoothing processing, for image data which has already been subjected to image processing by the dither method. An object of the present invention is to provide a method for processing binary image data in which dither processing and smoothing processing do not conflict with each other.

Furthermore, without using a storage means such as a page memory for recording image data, an interpolation for performing a smoothing process from an original binary image with a small memory and a hardware having a simple configuration. Provided is a processing method for obtaining high-speed and clear image data capable of continuously generating images in real time.

[0015]

Means for Solving the Problems In order to solve the above problems, the present invention has taken the following measures.

According to a first aspect of the present invention, there is provided a recording head having a plurality of pixel forming elements arranged in a main scanning direction with respect to an image forming body movable in a sub-scanning direction. In a method of processing binary image data applied to an image forming apparatus for forming a desired image by driving a forming element based on binary image data, the input binary original image data is converted to n × n or nx m (n and m are the number of bits) are recognized by a grid-like matrix pattern, and this pattern is compared with a plurality of discrimination patterns stored in advance, and is smaller than the pixels of the original image according to the discrimination pattern that matches the pattern. Interpolated image data of dot pixels is generated, and the original image data and the interpolated image data are alternately output by the recording head in a 1/2 line cycle, so that the image data subjected to the smoothing process is output. It is characterized by forming.

According to a second aspect of the present invention, in the first aspect of the present invention, the pixel forming element is formed of an LED, and the lighting time of the LED is shorter than the lighting time when printing the original image. To form an interpolated pixel of a dot smaller than the pixel of.

According to a third aspect of the present invention, in the second or third aspect of the present invention, there are provided n stages of n or m D flip-flops connected in series, and the output terminal of each stage is provided on a first-in first-out basis. A predetermined input terminal of a line memory (FIFO) is connected, and an output terminal of the FIFO corresponding to the input terminal is connected to an input terminal of a D flip-flop of the next stage, whereby an n × n or n × m grid is connected. Generate a pattern of a shape matrix.

According to a fourth aspect of the present invention, the interpolation image data is generated in the same n × n or n × m lattice matrix pattern as the original image data.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the binary image data of the input original image is serial image data developed by bitmap.

According to a sixth aspect of the present invention, it is detected whether or not there is a dither image area in the binary image data to be smoothed.
It is characterized in that no interpolated image data for smoothing processing is generated for the image area.

According to a seventh aspect of the present invention, the input binary image data is temporarily stored as an n × n or n × m lattice matrix pattern (where n and m are the number of bits). A method of comparing the stored pattern with a plurality of separately stored discrimination patterns in advance and generating interpolated image data according to the discrimination pattern that matches the temporarily stored pattern, wherein the temporarily stored pattern is It is characterized in that whether or not there is a dither image area is detected on the basis of, and when it is detected that there is a dither image area, no interpolated image data is generated for the dither image area.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, one or two M × M matrices on the left and right sides of the n × n matrix (where M is a grid pattern when dither processing is assumed to be performed) When the pattern of the n × n matrix at a predetermined position in M> n) matches the pattern of the arbitrary n × n matrix, the image area of the M × M matrix is a dither image. It is characterized in that it is determined that it has an area.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the dither processing is performed by a 4 × 4 matrix or an 8 × 8 matrix, and the smoothing processing is performed by a 3 × 3 matrix.
It is applied in a matrix.

According to a tenth aspect of the present invention, there is provided a recording head having a pixel forming element array in which a plurality of pixel forming elements are arranged in the main scanning direction, and an image which moves relatively to the recording head in the sub scanning direction. A formed body, a head control unit for controlling on / off of each of the pixel forming elements in synchronization with the movement of the 1/2 line of the image formed body in the sub-scanning direction;
Value image data is n × n or n × m (n and m are the number of bits)
The pattern of the input data identified by the pattern of the lattice matrix is compared with a plurality of discrimination patterns stored in advance, and the interpolated image data is interposed between the lines according to the discrimination pattern that matches the pattern of the input data. , And a data selector unit that alternately outputs the original image data and the interpolated image data output from the pattern match identification unit in a 1/2 line cycle.

According to an eleventh aspect of the present invention, there is provided a recording head having a pixel forming element array in which a plurality of pixel forming elements are arranged in the main scanning direction, and an image which moves relative to the recording head in the sub scanning direction. A formed body, a head control unit for controlling on / off of each of the pixel forming elements in synchronization with the movement of the 1/2 line of the image formed body in the sub-scanning direction;
The value image data is identified by an n × n matrix pattern,
A pattern match identification unit that compares the identified data pattern with a plurality of discrimination patterns stored in advance, and generates interpolated image data between lines of the line according to the discrimination pattern that matches the pattern of the input data; Detects whether a dither image area is included in the detected pattern, and does not generate interpolation image data for the dither image area in the pattern match identification unit when it is detected that the dither image area is included. And a data selector unit that alternately outputs the original image data and the interpolated image data output from the pattern match identification unit in a 1/2 line cycle.

According to a twelfth aspect of the present invention, there is provided an image forming body movable in the sub-scanning direction, and a pixel forming element array arranged to face the image forming body and having a plurality of pixel forming elements arranged in the main scanning direction. A printhead having: a head control unit that controls each pixel forming element of the printhead to be driven based on binary image data in synchronization with movement of the image forming body in the sub-scanning direction; A pattern match identification unit that generates an interpolated pixel having a diameter smaller than the diameter of the original pixel between the Nth line and the (N + 1) th line when the pattern of the n × n matrix of the image data is a predetermined pattern; When generating an image, it is detected whether or not there is a dither image area in the original image, and when it is detected that there is a dither image area, a dither image area detection that does not generate an interpolation image in the area is performed. , A first-in first-out line memory (FIFO) that stores the original image and the interpolated image as serial data, and counts one at a half line cycle. The original image and the interpolated image are alternately switched and sent to the recording head controller. And a data selector unit.

According to a thirteenth aspect, in the twelfth aspect, the pixel forming element is an LED, and a pixel having a desired diameter is formed by selecting a lighting time of the LED.

According to a fourteenth aspect of the present invention, there is provided an LED recording head comprising a photosensitive drum rotating in the sub-scanning direction, a charging means for uniformly charging the photosensitive drum, and a plurality of LEDs arranged in the main scanning direction. And image processing means for performing smoothing processing on the input binary image data for areas other than the dither image area to form interpolated pixels having a size smaller than the original pixel between lines, and image data processed by the image processing unit. Head control means for selectively turning on each LED of the recording head to form an electrostatic latent image on the photoconductor drum, and developing means for developing the electrostatic latent image with toner to form a toner image A transfer unit for transferring the image onto a recording medium; and a fixing unit for fixing the image transferred to the recording unit on the recording unit.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. The present invention can be basically preferably applied to an image forming apparatus such as an LED printer having a fixed pixel pitch in the main scanning direction. Therefore, in the following description, mainly LED (Light Emitting Diode)
However, the present invention is not limited to this, and is applicable to other printers in which the image forming elements are fixedly arranged in the main scanning direction, such as an inkjet printer and a thermal printer. May also be applied.

Secondly, in view of the phenomenon that the image deteriorates when the dithered image area (“dithered image area”) is subjected to the smoothing processing, the present invention uses the original image in generating the interpolated image. Whether or not there is a dither image area in the image is detected, and if there is a dither image, no interpolation image is generated in the area.

Third, an n × n bit (one bit corresponds to one dot pixel) matrix pattern and an M × M bit matrix pattern adjacent to the pattern are defined for smoothing processing. To determine whether there is a dither image area by determining whether or not the pattern matches. In this specification, “n × n bit matrix” is replaced with “n × n
It may be abbreviated as "matrix", but the contents are the same.

As described above, the present invention is applied to an image forming apparatus having a recording head in which a plurality of pixel forming elements (hereinafter, referred to as LEDs) are fixedly arranged in the main scanning direction. Replaces the conventionally known method of generating interpolated pixels between pixel pitches in the main scanning direction, and basically converts the interpolated image in the sub-scanning direction, that is, in the middle between the Nth line and the N + 1th line of the original image, that is, It is characterized in that it is generated in 1/2 line. It is desirable that such an interpolated image be printed with pixels smaller than the diameter of the pixels of the original image. Such a small print can be obtained by controlling the lighting time of the LED to be shorter than the lighting time used when printing the original image.

FIG. 4 shows an example of a 3 × 3 matrix pattern to be subjected to smoothing processing for forming an interpolated pixel between the Nth line and the N + 1th line. First, FIG.
Is different from the pattern of the laser printer having a step of 1 bit in the main scanning direction described in the example of FIG.
A pattern having a step of 1 bit in the sub-scanning direction is targeted for smoothing. FIG. 5 shows an example in which a small-diameter interpolation pixel is added between the N-th line and the (N + 1) -th line in the sub-scanning direction with respect to the original image of the pattern in FIG.

Before and after the description, the reception of binary image data will be described. Image data that has been bit-mapped from a host computer, a scanner, or a controller is transmitted to an image forming apparatus such as a printer or a plotter. Can be The transfer of the image data is sent in the form of serial data or parallel data such as 1 byte or 2 bytes. In the case of parallel data, the data is converted into serial data in the image forming apparatus to simplify the processing.

FIG. 1 shows a case where the original image data 1 is sent as 8-bit parallel data from a host device. The original image data 1 is sent to a first-in first-out line memory (FIFO) 2 line by line, and after absorbing an asynchronous operation with a processing system inside the image forming apparatus, the original image data 1 is converted into serial data by a parallel / serial conversion unit 3. Are output as binary original image serial data 4.

FIGS. 2 and 3 show means for forming an interpolated image for smoothing processing based on the original image serial data 4 output in FIG. In the illustrated example, the original image is recognized and processed as a 3 × 3 matrix pattern.

As shown particularly in FIG. 2, the original image serial data 4 is connected to the original image input terminal 6 (input terminal of the D flip-flop 7) of the first stage of the "original image 3 × 3 matrix" means. The “original image 3 × 3 matrix” means is a means for recognizing the original image serial data 4 in a 3 × 3 bit lattice matrix pattern, and includes a stage formed by connecting three D flip-flops in series. It has three stages, that is, a first stage composed of D flip-flops 7, 8, and 9, a second stage composed of D flip-flops 12, 13, and 14, and a third stage composed of D flip-flops 15, 16, and 17. The outputs of the last D flip-flops 9, 14, 17 of the first, second, and third stages are respectively connected to input terminals D5, D6, and D7 of a first-in first-out line memory (FIFO) 11, Outputs from the output terminals Q5 and Q6 corresponding to the input terminals D5 and D6 of the FIFO are connected to the input terminals of the D flip-flops 12 and 15 of the next stage, respectively, and are temporarily stored. Also, the third stage 15 of the FIFO 11
An original image serial data output 18 is output from an output terminal Q7 corresponding to the input terminal D7 for the input signals. This output will be described later separately.

In the above example, the case where the original image is recognized by a pattern of a 3 × 3 matrix has been described. However, a matrix of any other number of bits other than 3 bits may be used. Expressed as an n or n × m matrix. Further, the FIFO 11 preferably has a bit space larger than the maximum number of pixels of one line handled by the image forming apparatus.

By reading the FIFO from the output terminal Q5 of the FIFO 11 at a timing synchronized with the first bit of the line of the original image serial data 4, serial image data delayed by one line can be extracted. The serial image data delayed by one line is connected to the input terminal of the second stage of the “original image 3 × 3 matrix” by the D flip-flops 12, 13 and 14, that is, the input terminal of the D flip-flop 12, and Output of FIFO1
1 input terminal D6. The same applies to the FIF
Image data delayed by three lines from the input of the original image serial data 4 of the matrix can be extracted from the output terminal Q7 of O11. Thus, the original image serial data 4
Can be recognized as a 3 × 3 matrix pattern. Reference numerals 15, 16, and 17 denote D flip-flops for generating image data of the third line.

On the other hand, in order to form an interpolated image for performing a smoothing process, an "interpolated image 3 × 3 matrix"
Is configured. Symbols 19 to 21, 22 to 24, 25 to 27
Are D flip-flops for the first, second, and third lines, respectively, and reference numerals 28, 29, and 30 are OR gates, respectively. , Interpolation pixel injection 2, interpolation pixel injection 3
Is entered. The difference from the “original image 3 × 3 matrix” is that the image input of the first stage is connected to GND (Low), and the output of the previous D flip-flop is ORed with the second and third stages. That is, an interpolation pixel injection terminal is provided at the gate. With such a configuration, the interpolated image serial data output 32 is output from the Q3 output terminal of the FIFO.

In the above example, the “original image 3 × 3 matrix”
And an "interpolated image 3 × 3 matrix"
, And the “original image 3 × 3 matrix” and the “interpolated image 3 × 3
With the same configuration of the “matrix”, the original image and the interpolated image operate at the same timing, so that there is an advantage that control is easy.

Returning again to the “original image 3 × 3 matrix”, the output MP [2: 0] [2: 0] of the 3 × 3 matrix
Is input to the pattern match identification unit 31 as shown in FIG. The pattern match identification unit 31 determines that “the original image 3 ×
The pattern recognized by the “3 matrix” is compared with a plurality of discrimination patterns to be subjected to smoothing stored in advance in the pattern match identification unit 31, and when a matching discrimination pattern is detected, the “interpolated image” is determined according to the pattern. Interpolated pixel injection terminals 1 and 2 corresponding to “3 × 3 matrix”
And / or 3 to output signal 1 (High, black image).

FIG. 9 shows an example of a pattern in the case where the interpolation pixel injection 1 and the interpolation pixel injection 2 are output. FIG. 10 and FIG. 11 are pattern examples in the case of outputting to interpolation pixel injection 2 and interpolation pixel injection 3, respectively. Here, the original images are sequentially transferred without any processing.

In the above embodiment, the FIFO for storing the original image data and the interpolated image data as serial data
Although 11 is completed in the same package, when increasing the number of lines of the matrix, the original image data and the interpolated image data may be stored in FIFOs of separate packages. If the number of bits in one line cannot be accommodated in one FIFO, the data may be divided into a plurality of FIFOs and stored. In such a case, a joint between the FIFOs may be used. In order to remove the discontinuous portion, one byte or more is overlapped, stored in the FIFO and processed, and the overlapped portion is removed at the post-processing stage.

Next, the means for detecting whether or not the image input data to be processed includes a dither image area will be described. As described above, if the size of the pattern match for pattern match identification is performed using only a 3 × 3 matrix, an interpolation image for smoothing is generated even when the original image data includes a dither image area. There are drawbacks. This causes competition between dither processing and smoothing processing, and hinders high-quality images.

Normally, a dither pattern for performing the dither processing often uses 16 gradations of 4 bits × 4 bits or 64 gradations of 8 bits × 8 bits. In this case, the image has 4 bits. The same pattern is repeated every 8 bits or every 8 bits. Therefore, the present invention is provided with a means for detecting these dither patterns, and when the image data to be smoothed has a dither image area, no interpolation image data is generated for the image area.

For example, referring to FIG. 12, when viewing the 3 × 3 “9 pixels to be smoothed” shown in the center, 1
In the case of a 6-gradation dither pattern, nine pixels separated by 4 bits on the left and right are used, and in the case of a dither pattern of 64 gradations, the same pattern is used by nine pixels separated by 8 bits on the left and right, using the same pattern. If any one of the nine pixels in the four locations matches the pattern with the “smoothing target pixel 9” at the center, the interpolation image is set to 0 (Low, white image).

FIG. 6 is a block diagram showing the storage of the interpolated image obtained by adding the dither pattern detection, and FIG. 7 is a block diagram for outputting the interpolated image injections 1, 2, and 3. In FIG. 6, “Original image 20
X3 matrix "and" interpolated image 20x3 matrix "
Are D flip-flops, and in 4 bits, the “original image 20 × 3 matrix” is from KP [...] to OP [...], and the “interpolated image 20 × 3 matrix” is FP [ ...] to JP [...]. Here, the D flip-flops shaded are described to facilitate understanding of the operation principle, but actual data is
Since it is fixed at the ND level, it can be omitted. As in the example shown in FIG. 2, the “original image 20 × 3 matrix” and the “interpolated image 20 × 3 matrix” are
With the same configuration including 40, there is an advantage that the original image and the interpolated image operate at the same timing, so that control is easy.

FIFO is used as serial data of one line.
The original image serial data 41 and the interpolated image serial data 42 stored in the memory 40 are read out and output from the output terminals Q7 and Q3 of the FIFO 40 at the same timing, respectively, and as shown in FIG. It is led to parts 43 and 44. This is because it takes time to transfer the data as it is as serial data, and it is difficult to perform the next data processing, so that the data is converted to parallel data.

The parallel original image data and the parallel interpolated image data converted by the serial / parallel converters 43 and 44 are temporarily transferred to independent FIFOs 45 and 46, respectively, and the cycle (1/1) of the original one line cycle is used. By the operation of the 1-bit 1/2 line counter 47 that counts one at a time of two lines, the original image and the interpolated image are alternately switched at a period of 1/2 line, and the LED head controller 4
9 and further transferred to the LED head 50. The 1-bit 1/2 line counter 47 is a FIFO4
5 and the FIFO 46, but the FIFO 45
In order to make the output of the FIFO 46 and the output of the FIFO 46 alternate, one of them (the FIFO 46 in the illustrated example) is an anti-input. A section for performing such alternate output is referred to as a data selector section, and is described by a block indicated by reference numeral 48 in FIG. Here, the LED head control unit 49 switches the LED lighting time for printing the original image and the LED lighting time for printing an interpolated image shorter than the predetermined LED lighting time in accordance with the image. The smoothed printing is controlled by forming an interpolated image on the step.

It is preferable that the LED lighting time for the original image can be changed in the service mode so that it can be adjusted even in the user environment.
It is preferable that the setting value of the D lighting time allows selection of what percentage of the time for the original image to use, and is fixed at the time of factory shipment.

This is because it is necessary to carefully and properly select the LED lighting time for the interpolation image. For example, if an inappropriately large LED lighting time is set, the image deteriorates. Although the conditions are different depending on the photosensitivity of the photosensitive drum, the development process characteristics, and the like, which will be described later, a favorable result was obtained in which the LED lighting time for the interpolation image was about 25% of the LED lighting time of the original image.

FIG. 13 shows an example of an image forming apparatus using the above-described image data processing method. In this example, an image forming apparatus using an electrophotographic method is used, and an image forming body denoted by reference numeral 60 has a photoconductive layer on the surface of a metal material such as aluminum, and is rotatable about an axis. It is provided in. The surface of the image forming body is charged to a predetermined polarity by contacting the charging roller 61 or the like biased at a predetermined polarity or by ionizing with a corona discharger or the like. By irradiating the charged surface with a desired image by the LED head 50, the charge of the irradiated portion disappears, and an electrostatic latent image is formed by the irradiated portion and the non-irradiated portion.

The head 50 has a plurality of LEDs on the same substrate.
Are arranged in the main scanning direction (the axial direction of the image forming body), and the light irradiation surface thereof is arranged so as to face the surface of the image forming body 60. Each LED of the recording head 50 is controlled in synchronization with the rotation of the image forming body 60 in the direction of the arrow, and an LED corresponding to a desired image is turned on to expose a selected area on the surface of the image forming body 60. be able to.

The light-irradiated portion of the surface of the image forming body 60 is discharged, and the surface potential decreases. Thus, an electrostatic image is formed on the surface of the image forming body 60.

Next, the electrostatic latent image formed on the surface of the image forming body 60 is supplied with a developer called a toner by a developing means 62, developed, and converted into a visible image (toner image). The developer includes a magnetic one-component toner, a non-magnetic one-component toner or a two-component developer.

The visualized toner image is transferred by a transfer means 63 onto a recording medium such as paper. Transfer means 63
May be, for example, a transfer roller biased at a predetermined polarity. The toner image formed on the image forming body 60 is electrostatically applied to the surface of the recording medium by applying a charge of a predetermined polarity from the back side of the recording medium. Suction to adhere. Further, the transfer unit 63 may be a transfer corona discharge device using corona discharge.

The recording medium carrying the toner image is then sent to the fixing means 64. In the illustrated example, the transfer means 64 is a heating roller 6 which has been subjected to offset prevention processing in which the internal heating is performed.
4a, and a pressure roller 64b that is brought into contact with the heating roller 64a at a predetermined pressure. The recording medium carrying the toner image is conveyed between these rollers. Established in

On the other hand, the toner remaining on the surface of the image forming body 60 without being transferred is removed from the image forming body 60 by the cleaning means 65. The cleaning unit 65 may be a cleaning blade that is pressed against the image forming body 60 as shown in the drawing and scrapes the toner thereon, or may be a cleaning brush that sweeps the toner on the image forming body 60. Good.

After the cleaning, the surface of the image forming body 60 is uniformly exposed to light by the eraser lamp 66, whereby the residual charge on the image forming body 60 is eliminated, and the potential is reduced to zero.

On the other hand, the recording head 50 is driven as follows. The binary original image serial data 1 input from the external device and subjected to parallel / serial conversion is detected as an n × n (3 × 3 in the above example) matrix pattern. The detected pattern of the input data is compared with a plurality of pre-stored discrimination patterns by the pattern match identification unit 3, and if there is a discrimination pattern that matches the pattern of the input data, the sub pattern of the image is determined in accordance with the discrimination pattern. Grow interpolated image data between lines in the scanning direction. On the other hand, the dither area detection unit 67 detects whether or not the input image includes a dither image area. When the dither image area detection section 67 detects that the input image includes the dither image area, it instructs the pattern match identification section 62 not to generate the interpolation image data for the dither image area. The data selection section 48 alternately outputs the original image data and the interpolated image data output from the pattern match identification section 62 at a cycle of 1/2 line.
In accordance with the smoothed image data output from the pattern match identification unit 3, each LED of the recording head 50 is turned on in synchronization with the movement of the image forming body 50 in the sub-scanning direction of 1/2 line. Drive.

FIGS. 14 (a) and 14 (b) show the state of the original image and the interpolated image transferred alternately in the one-line cycle and the half-line cycle, respectively.

In the above example, the case where the electrophotographic method is used as the image forming method and the LED is used as the pixel forming element has been described.
The method is not limited to such a device.

[0065]

As described above, according to the present invention, an interpolated image for performing a smoothing process can be continuously generated in real time from a base binary image with a small memory and hardware having a simple configuration. . In particular, in an image forming apparatus using an LED head or the like having a fixed pixel pitch in the main scanning direction, a high-quality, high-speed, and low-cost apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conversion unit for outputting input original image parallel data as serial data.

FIG. 2 is a diagram for explaining a storage unit of an original image and an interpolation image.

FIG. 3 is a block diagram for explaining injection of an interpolation image.

FIG. 4 is a diagram illustrating an example of a pattern to be smoothed;

FIG. 5 is a diagram illustrating a pattern example of an interpolation image to be added;

FIG. 6 is a diagram illustrating a generation unit of an interpolated image in which detection of a dither image region is added.

FIG. 7 is a block diagram for explaining injection of an interpolation image.

FIG. 8 is a block diagram for explaining operations of a serial / parallel converter and an LED head controller for performing a smoothing process.

9 is a diagram illustrating an example of a target pattern corresponding to interpolation pixel injections 1 and 2 in FIG. 7;

FIG. 10 is a diagram showing an example of a target pattern corresponding to interpolation pixel injection 2 in FIG. 7;

11 is an example of a target pattern corresponding to interpolation pixel injection 3 in FIG. 7;

FIG. 12 is a diagram illustrating an example of target pixels for detecting a dither image area.

FIG. 13 is a diagram illustrating an example of an image forming apparatus according to the present invention.

FIG. 14 is a diagram showing a state of original image transfer in one line cycle, original image transfer and interpolated image transfer alternately performed in a 1/2 line cycle.

FIG. 15 is a diagram illustrating an example of a pattern to be smoothed in a laser printer.

FIG. 16 is a diagram illustrating an example of a smoothing image in a laser printer. .

[Explanation of symbols]

 Reference Signs List 1 original image data 1 2 line memory (FIFO) 3 parallel-serial conversion unit 3 6 original image input terminal 7-9 D flip-flop 12-14 D flip-flop 15-17 D flip-flop 19-21 D flip-flop 22-24 D flip-flop 25 to 27 D flip-flop 28 to 30 OR gate 40 FIFO 43, 44 serial / parallel conversion unit 45, 46 FIFO 47 bit counter 48 data selector unit 49 head control unit 50 LED head 60 image forming body 67 dither area detection Department

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[Procedure amendment]

[Submission date] June 25, 2001 (2001.6.2)
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

In a laser printer, for example, such a small interpolation pixel can be generated by controlling the lighting time (pulse width in the main scanning direction) of the laser beam for each pixel. The object is achieved by irradiating a pixel having a half diameter or a half width onto the image forming body. FIG. 15 shows an example of an original pixel pattern of a 3 × 3 dot matrix to be smoothed in a laser printer. It is understood that the portion indicated by black filling is the original pixel portion of the black character, and has a step between adjacent pixel columns. 16, as shown in FIG. 15
A black interpolated pixel (indicated by a hatched portion in the figure) having a width half the width of the original pixel is formed between the original pixels in the main scanning direction of the pattern No. 3 and smoothing processing is performed. It is an example. Thus, in a device such as a laser printer that can adjust the image pitch in the main scanning direction, the smoothing process can be easily performed by adjusting the pixel pitch in the main scanning direction.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

FIG. 4 shows an example of a 3 × 3 matrix pattern to be subjected to smoothing processing for forming an interpolated pixel between the Nth line and the N + 1th line. Earlier in Figure 15
Is different from the pattern of the laser printer having a step of 1 bit in the main scanning direction described in the example of FIG.
A pattern having a step of 1 bit in the sub-scanning direction is targeted for smoothing. FIG. 5 shows an example in which a small-diameter interpolation pixel is added between the N-th line and the (N + 1) -th line in the sub-scanning direction with respect to the original image of the pattern in FIG.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Before and after the description, the reception of binary image data will be described. Image data that has been bit-mapped from a host computer, a scanner, or a controller is transmitted to an image forming apparatus such as a printer or a plotter. Can be Of such image data transfer is to
The data is sent in the form of real data or parallel data such as 1 byte or 2 bytes. In the case of parallel data, the data is converted into serial data in the image forming apparatus to simplify the processing.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/04 G06T 5/20 F-term (Reference) 2C087 AC08 BA03 BC07 BD01 2C162 AE21 AE28 AE47 AF13 AF56 AF71 FA04 FA17 2H076 AB42 AB66 AB76 5B057 AA11 CA06 CA07 CA12 CA16 CB06 CB07 CB12 CB16 CE05 CE13 CH11 DB02 DB05 DB08 5C077 LL05 LL18 MP04 NN05 NN08 NN09 NN17 PP02 PP27 PP28 PP55 PQ22 RR19 TT02

Claims (14)

[Claims] 1. A recording head having a plurality of pixel forming elements arranged in a main scanning direction with respect to an image forming body movable in a sub-scanning direction.
In a method of processing binary image data applied to an image forming apparatus that forms a desired image by driving based on value image data, the input binary original image data is converted to n × n or n × n.
X m (n and m are the number of bits) are recognized by a pattern of a lattice matrix, and this pattern is compared with a plurality of discrimination patterns stored in advance, and pixels are compared with pixels of the original image according to a discrimination pattern that matches the pattern. Binary image data characterized by generating interpolated image data of small dot pixels, and performing smoothing processing by alternately outputting the original image data and the interpolated image data at a half line cycle by the recording head. Processing method. 2. The method according to claim 1, wherein the pixel forming element is an LED.
2. The binary image data according to claim 1, wherein an interpolated pixel of a dot smaller than a pixel of the original image is formed by setting a lighting time of the ED to a time shorter than a lighting time when the original image is printed. Processing method. 3. An n-stage having n or m D flip-flops connected in series, and an output terminal of each stage is connected to a predetermined input terminal of a first-in first-out line memory (FIFO). An output terminal of the FIFO corresponding to the input terminal is connected to an input terminal of a next-stage D flip-flop, thereby generating an nxn or nxm lattice pattern. 2 described in 1 or 2
How to process value image data. 4. The processing of binary image data according to claim 1, wherein the interpolation image data is generated in the same n × n or n × m grid pattern as the original image data. Method. 5. The binary image data processing method according to claim 1, wherein the input binary image data of the original image is serial image data developed by bitmap. 6. Detecting whether or not a dither image area exists in binary image data to be subjected to smoothing processing, and when detecting that there is a dither image area, interpolation image data for smoothing processing on the image area is detected. A method for processing binary image data, characterized by not generating. 7. The input binary image data is temporarily stored as an n × n or n × m lattice matrix pattern (n and m are the number of bits), and the temporarily stored pattern is stored in advance. A method of generating interpolated image data in accordance with a discrimination pattern that matches the temporarily stored pattern by comparing with a plurality of discrimination patterns stored separately,
Detecting whether or not there is a dither image area based on the temporarily stored pattern; and detecting that there is a dither image area, generating no interpolation image data for the dither image area. A method for processing binary image data. 8. One or two M × M matrices on the left and right sides of an n × n matrix (M is the number of bits of a dither pattern of a lattice matrix when it is assumed that dither processing is performed, and M> n) When the pattern of the n × n matrix at a predetermined position in the above matches the pattern of the arbitrary n × n matrix, it is determined that the image area of the M × M matrix has a dither image area. The method for processing binary image data according to claim 7, characterized in that: 9. The method according to claim 8, wherein the dither processing is performed in a 4 × 4 matrix or an 8 × 8 matrix, and the smoothing processing is performed in a 3 × 3 matrix.
A method for processing binary image data according to any one of the preceding claims. 10. A recording head having a pixel forming element array in which a plurality of pixel forming elements are arranged in a main scanning direction;
An image forming body that moves relatively in the sub-scanning direction with respect to the recording head, and on / off control of each of the pixel forming elements in synchronization with the movement of the image forming body in the sub-scanning direction by a half line. And a head control unit for executing the input binary image data
Xn or n × m (where n and m are the number of bits) are identified by a grid-like matrix pattern, and the identified input data pattern is compared with a plurality of pre-stored discrimination patterns to match the input data pattern. A pattern match identification unit that generates interpolated image data between lines according to the discrimination pattern, and data that alternately outputs the original image data and the interpolated image data output from the pattern match identification unit in a 1/2 line cycle An image forming apparatus comprising: a selector unit. 11. A recording head having a pixel forming element array in which a plurality of pixel forming elements are arranged in a main scanning direction;
An image forming body that moves relatively in the sub-scanning direction with respect to the recording head, and on / off control of each of the pixel forming elements in synchronization with the movement of the image forming body in the sub-scanning direction by a half line. And a head control unit for executing the input binary image data
× n matrix pattern, the identified data pattern is compared with a plurality of pre-stored discrimination patterns, and interpolated image data is inserted between lines between lines according to the discrimination pattern that matches the input data pattern. A pattern match identifying unit to be generated, and detecting whether a dither image area is included in the detected pattern. When it is detected that a dither image area is included, the pattern match identifying unit A dither image area detection unit that instructs not to generate interpolation image data for an image region, and a data selector unit that alternately outputs original image data and interpolation image data output from the pattern match identification unit in 1-bit 1/2 lines. An image forming apparatus comprising: 12. An image forming body movable in a sub-scanning direction, and a recording head having a pixel forming element array arranged to face the image forming body and having a plurality of pixel forming elements arranged in the main scanning direction. A head control unit that controls each pixel forming element of the recording head to be driven based on binary image data in synchronization with movement of the image forming body in the sub-scanning direction; When the pattern of the n matrix is a predetermined pattern, between the N line and the N + 1 line, a pattern match identification unit that generates an interpolation pixel having a diameter smaller than the diameter of the original pixel; When detecting whether there is a dither image area in the original image and detecting that there is a dither image area,
A dither image area detection unit that does not generate an interpolated image in the area, and a first-in first-out line memory (FIFO) that stores the original image and the interpolated image as serial data
And a data selector unit that counts one at a half line cycle, alternately switches between the original image and the interpolated image, and sends it to the recording head control unit. 13. The image forming apparatus according to claim 12, wherein the pixel forming element is an LED, and a pixel having a desired diameter is formed by selecting a lighting time of the LED. 14. A photosensitive drum rotating in a sub-scanning direction, charging means for uniformly charging the photosensitive drum, an LED recording head having a plurality of LEDs arranged in a main scanning direction, and Image processing means for performing smoothing processing on the binary image data for areas other than the dither image area to form interpolated pixels smaller in size than the original pixels between lines, and the recording head based on the image data processed by the image processing unit. Head control means for selectively lighting each LED to form an electrostatic latent image on the photosensitive drum; developing means for developing the electrostatic latent image with toner to form a toner image; An image forming apparatus, comprising: a transfer unit that transfers onto a recording medium; and a fixing unit that fixes an image transferred to the recording unit onto the recording unit.