JP2018094739A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more finely control the resolution of a print image and the printing start position of each pixel.SOLUTION: An image processing unit 15 of a printer 100 generates resolution information in which the resolution of one pixel unit of an image printed on the basis of image data is designated with the number having continuous 1 or 0, and position information in which the printing start position in a printing region of each pixel is designated in the one pixel unit, associates the resolution information, position information and image data with each other, and transmits them to a print unit 16. The print unit 16 prints an image on a sheet on the basis of the resolution information, position information and image data transmitted from the image processing unit 15.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  In an image forming apparatus such as a printer, rasterized image data is processed as image data for each color of Y (yellow), M (magenta), C (cyan), and K (black) after image processing, and a PWM (Pulse Width Modulation) circuit. Sent to. The PWM circuit converts the image data into a signal having a pulse width corresponding to the gradation and transmits the signal to an LD (Laser Diode) driver. The LD driver drives a laser light source (LD) based on a signal transmitted from the PWM circuit, irradiates the laser beam from the laser light source onto the photosensitive drum, performs exposure, and forms an electrostatic latent image on the photosensitive drum. To do. Thereafter, the toner image formed by the developing unit spraying the toner is transferred onto the printing paper and printed.

  In such an image forming apparatus, it is necessary to transfer image data of each color of YMCK at high speed or increase the number of bits of each color of YMCK in order to maintain gradation and achieve higher resolution. However, when the latter is performed, the amount of image data between the image processing substrate and the LD substrate increases.

  Therefore, for example, in Patent Document 1, a 1-bit natural image / character selection signal is added to each pixel, and in the case of a character image, processing is performed at 600 dpi-3 bits (high resolution / low gradation). Describes that an image is formed with an optimal resolution and gradation according to the type of image by processing at 300 dpi-6 bits (low resolution and high gradation).

  Further, for example, in Patent Document 2, a print position and a print pulse width are determined based on whether or not image data of an image group having a plurality of continuous pixels as one pixel is printed, and a PWM circuit is determined based on the determined print position and pulse width. Describes that a higher-quality image with higher quality can be formed by generating a pulse signal.

JP 7-256936 A JP 2003-136781 A

  However, in Patent Document 1, since switching of the resolution is only control of switching 1 or 0 with a 1-bit signal, only two resolutions can be switched. Also, when printing at a low resolution, the width of the print area per pixel increases, but the print start position in the print area of each pixel cannot be controlled, so that the image edge portion can be expressed smoothly. difficult.

  In Patent Document 2, there is no description about switching a plurality of resolutions. In addition, although the printing position in the image forming area of one pixel can be controlled, since the printing position is controlled according to whether or not image data is printed, fine position control cannot be performed.

  An object of the present invention is to enable finer control of the resolution of an image to be printed and the print start position of each pixel.

In order to solve the above-mentioned problem, the invention described in claim 1
An image forming apparatus including a printing unit that prints an image on paper based on image data,
Resolution information for designating the resolution of one pixel unit of the image to be printed based on the image data by the number of consecutive 1s or 0s, and the printing start position in the printing area of each pixel of the image are designated by one pixel unit. An image processing unit that generates position information and associates the resolution information, the position information, and the image data with each other and transmits the image data to the print unit;
The printing unit prints an image on a sheet based on the resolution information, the position information, and the image data transmitted from the image processing unit.

The invention according to claim 2 is the invention according to claim 1,
The resolution information indicates a lower resolution as the number of consecutive 1s or 0s increases.

The invention according to claim 3 is the invention according to claim 2,
One bit of the resolution information corresponds to image data of a predetermined number of bits, and image data of the number of bits obtained by multiplying the number of consecutive 1 or 0 of the resolution information by the predetermined number of bits corresponds to one pixel. Combined as image data, a gradation for one pixel corresponding to the resolution information is expressed.

The invention according to claim 4 is the invention according to claim 2 or 3,
One bit of the resolution information corresponds to position information of a predetermined number of bits, and the position information is represented by data of the number of bits obtained by multiplying the number of consecutive 1 or 0 of the resolution information by the predetermined number of bits. A print start position for one pixel corresponding to the resolution information is designated.

The invention according to claim 5 is the invention according to claim 4,
The position information can specify the print start position of image data for one pixel corresponding to the resolution information from the larger print start positions as the resolution specified by the resolution information is lower. .

The invention according to claim 6 is the invention according to any one of claims 1 to 5,
The image processing unit determines a type of the image data, and determines a resolution of an image to be printed based on the image data based on the type of the image data.

  According to the present invention, it is possible to finely control the resolution of an image to be printed and the print start position of each pixel.

FIG. 2 is a block diagram illustrating a functional configuration of a printer. It is a figure which shows the data output to the printing part from the image processing part of FIG. 3 is a timing chart when image data, resolution information, and position information are transmitted from the image processing unit of FIG. 2 to the PWM circuit. (A) is a diagram showing a print start position when the resolution is 2400 dpi, (b) is a diagram showing a print start position when the resolution is 1200 dpi, and (c) is a diagram showing a print start position when the resolution is 600 dpi. It is. It is a figure which shows typically the image edge printed by making the print start position into the right alignment with the resolution of 1200 dpi. FIG. 5 is a diagram schematically illustrating image edges printed at a resolution of 600 dpi with a print start position from the top right-justified 1, right-justified 2, right-justified 3, and right-justified 4. FIG.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
In this embodiment, an example in which the image forming apparatus of the present invention is applied to a printer will be described. However, the scope of the invention is not limited to the illustrated examples.

First, the configuration will be described.
FIG. 1 shows a functional configuration of the printer 100. The printer 100 prints an image on printing paper based on image data.
As shown in FIG. 1, the printer 100 includes an overall control unit 11, a storage unit 12, a display unit 13, a data input unit 14, an image processing unit 15, a printing unit 16, and the like.

  The overall control unit 11 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the overall control unit 11 reads the system program and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operation of each unit of the printer 100 according to the expanded programs.

  The storage unit 12 is configured by a nonvolatile semiconductor memory, an HDD (Hard Disk Drive), and the like, and stores various programs executed by the overall control unit 11 as well as parameters and data necessary for each unit.

  The display unit 13 includes an LCD (Liquid Crystal Display), and displays various screens on the LCD in accordance with control by the overall control unit 11.

  The data input unit 14 receives image data of a print job output from an external device via a LAN (Local Area Network) cable or the like (not shown), performs RIP processing (rasterization), and outputs it to the image processing unit 15.

The image processing unit 15 performs various image processing including color conversion on the input image data.
Further, the image processing unit 15 determines the type of the image data based on the image type information included in the attribute information of the input image data, and prints based on the image data according to the determined type of the image data. The resolution of the image to be determined is determined, and resolution information for designating the determined resolution in units of one pixel is generated. Further, the resolution of the image data is converted according to the determined resolution. For example, when the type of image data is character data, resolution is required rather than gradation, so that resolution information specifying high resolution (2400 dpi or 1200 dpi) is generated. When the type of image data is graphic data or photo data, it cannot be appropriately expressed if the number of gradations is small, and therefore, resolution information for specifying a low resolution (600 dpi) is generated. Here, in the present embodiment, the input image data is 8 bit 256 gradation, and is converted to 2 bit 4 gradation when the resolution is 2400 dpi, and 4 bit 16 gradation when the resolution is 1200 dpi. At 600 dpi, the 8-bit 256 gradation remains unchanged.
Further, the image processing unit 15 determines the print start position in the print area of each pixel of the image to be printed based on the image type information and surrounding pixels included in the attribute information of the image data, and determines the determined print start position. Generate location information to be specified.
Then, as shown in FIG. 2, the image processing unit 15 associates (synchronizes) the image data of each pixel of Y, M, C, and K, the resolution information, and the position information with the printing unit 16. Transmit to the PWM circuit 161. In this embodiment, YMCK 2-bit image data, resolution information 1 bit, and position information 1 bit are associated with each other and transmitted to the PWM circuit 161. That is, 1-bit resolution information, 2-bit YMCK image data, and 1-bit position information are transmitted for one synchronization signal.

FIG. 3 shows a timing chart when image data, resolution information, and position information are transmitted from the image processing unit 15 to the PWM circuit 161.
As shown in FIG. 3, the resolution information designates the resolution of an image to be printed based on the transmitted image data by a continuous number of 1 or 0. For example, when 1 or 0 is 1 time, 2400 dpi is specified, when 2 times is continued, 1200 dpi is specified, and when 4 times is continued, 600 dpi is specified. As described above, the resolution information designates the resolution of an image to be printed by a continuous number of 1 or 0, so that the resolution and gradation can be controlled more finely than in the past.

As described above, 2 bits of image data correspond to 1 bit of resolution information, and image data for one pixel is obtained by multiplying 2 bits by the number of consecutive 1s or 0s (number of bits) of resolution information by 2 bits. Are combined to express the gradation for one pixel corresponding to the resolution information. That is, the image data for one pixel is 2 bits when the resolution is 2400 dpi, 4 bits when the resolution is 1200 dpi, and 8 bits when the resolution is 600 dpi.
Also, 1-bit position information corresponds to 1-bit resolution information, and the position information is converted into resolution information by data of the number of bits obtained by multiplying the number of consecutive 1 or 0 (number of bits) of the resolution information by 1 bit. Designates the corresponding print start position for one pixel. That is, the position information for one pixel is 1 bit when the resolution is 2400 dpi, 2 bits when the resolution is 1200 dpi, and 4 bits when the resolution is 600 dpi.

  Here, the width of the printing area of one pixel of the image to be printed differs depending on the resolution. When the resolution is high, the width of the printing area of one pixel is reduced, and when the resolution is low, the width of the printing area of one pixel is increased. For example, the width of one pixel printing area with a resolution of 1200 dpi is twice as large as 2400 dpi, and the width of one pixel printing area with 600 dpi is four times as large as 2400 dpi. That is, in the case of high resolution, since the width of the printing area of one pixel is small, fine control of the printing start position is not necessary, but the width of the printing area of one pixel becomes larger as the resolution becomes lower. If the printing start position is controlled in the same manner, smoothness of the image edge in the sub-scanning direction cannot be realized.

Therefore, in the present embodiment, as described above, when the resolution is 2400 dpi, the center-aligned print start position is designated using the position information of 1 bit per pixel. For example, center alignment (see FIG. 4A) is designated by the position information “0”.
When the resolution is 1200 dpi, the print start position of center alignment, left alignment, or right alignment is specified using position information of 2 bits per pixel as described above. For example, the position information “00” specifies center alignment, “01” specifies left alignment, and “10” specifies right alignment (see FIG. 4B).
When the resolution is 600 dpi, the print start position is designated using the position information of 4 bits per pixel as described above. For example, the position information “0000” specifies center alignment, “0001” to “0100” specifies left alignment 1 to 4, and “1001” to “1100” specifies right alignment 1 to 4 (see FIG. 4C).

The printing unit 16 includes a PWM circuit 161, an LD driver 162, an LD 163 for each color of YMCK, a photosensitive drum 164 for each color of YMCK, a developing unit 165 for each color of YMCK, a paper feeding unit and a conveyance path (not shown), and the like. Printing is performed by an electrophotographic method based on the image data, resolution information, and position information.
That is, when image data, resolution information, and position information are input from the image processing unit 15, the PWM circuit 161 determines the resolution of the image data based on the resolution information, and determines the image data and position information for one pixel. To do. Based on the determined resolution, image data, and position information, a PWM signal is generated and output to the LD driver 162. The LD driver 162 drives the LD 163 based on the PWM signal, controls the laser light emitted from the LD 163, that is, the exposure amount and the print start position, and irradiates the photosensitive drum with the laser light to perform exposure. An electrostatic latent image is formed. Thereafter, the toner image formed by the developing unit 165 spraying the toner is transferred to the printing paper and printed.

  FIG. 5 shows an image edge printed at a resolution of 1200 dpi with the print start position being right-justified. FIG. 6 schematically shows image edges printed at a resolution of 600 dpi with the print start position from the top right-justified 1, right-justified 2, right-justified 3, and right-justified 4. FIG. As shown in FIG. 6, with 600 dpi, the print start position can be set in more detail for each pixel than with 1200 dpi, and because of the high gradation, the number of gradations is set finely for each pixel and the image edge edge is set. Since the image can be printed, the image edge in the sub-scanning direction can be expressed smoothly.

As described above, according to the image processing unit 15 of the printer 100, the resolution information that specifies the resolution of one pixel unit of the image to be printed based on the image data by the number of consecutive 1s or 0s, and the printing of each pixel Position information for designating the printing start position in the area in units of one pixel is generated, and the resolution information, position information, and image data are associated with each other and transmitted to the printing unit 16.
Accordingly, the resolution of the image printed by the printing unit 16 and the print start position of each pixel can be controlled more finely.

  The resolution information indicates that the greater the number of consecutive 1s or 0s, the lower the resolution. Image data of a predetermined number of bits corresponds to 1 bit of the resolution information, and 1 or 0 of the resolution information is continuous. The image data of the bit number obtained by multiplying the number to be multiplied by a predetermined number of bits is combined as image data for one pixel to express a gradation for one pixel corresponding to the resolution information. Accordingly, it is possible to express with higher gradation as the pixel has a lower resolution.

  Also, one bit of resolution information corresponds to position information of a predetermined number of bits, and the position information is resolution information by data of the number of bits obtained by multiplying the number of consecutive resolution information 1 or 0 by the predetermined number of bits. The printing start position for one pixel corresponding to is designated. Therefore, as the resolution specified by the resolution information is lower, the print start position of the image data for one pixel corresponding to the resolution information can be specified from a larger number of print start positions.

  The image processing unit 15 determines the type of image data, and determines the resolution of an image to be printed based on the image data based on the type of image data. Therefore, it is possible to print an image based on the image data with a resolution corresponding to the type of the image data.

  Note that the description in the above embodiment shows a preferred example of the image forming apparatus according to the present invention, and the present invention is not limited to this.

  For example, in the above embodiment, the case where the image forming apparatus of the present invention is applied to an electrophotographic printer has been described as an example. However, the present invention is not limited to this. For example, a printer of another printing method such as an inkjet method, It may be applied to a copy machine or the like.

  In the above description, an example in which a non-volatile memory, a hard disk, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of the image forming apparatus can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Printer 11 Overall control part 12 Storage part 13 Display part 14 Data input part 15 Image processing part 16 Print part

Claims (6)

An image forming apparatus including a printing unit that prints an image on paper based on image data,
Resolution information for designating the resolution of one pixel unit of the image to be printed based on the image data by the number of consecutive 1s or 0s, and the printing start position in the printing area of each pixel of the image are designated by one pixel unit. An image processing unit that generates position information and associates the resolution information, the position information, and the image data with each other and transmits the image data to the print unit;
The image forming apparatus that prints an image on a sheet based on the resolution information, the position information, and the image data transmitted from the image processing unit.   The image forming apparatus according to claim 1, wherein the resolution information indicates a lower resolution as the number of consecutive 1s or 0s increases.   One bit of the resolution information corresponds to image data of a predetermined number of bits, and image data of the number of bits obtained by multiplying the number of consecutive 1 or 0 of the resolution information by the predetermined number of bits corresponds to one pixel. The image forming apparatus according to claim 2, wherein the image forming apparatus is combined as image data to express a gradation for one pixel corresponding to the resolution information.   One bit of the resolution information corresponds to position information of a predetermined number of bits, and the position information is represented by data of the number of bits obtained by multiplying the number of consecutive 1 or 0 of the resolution information by the predetermined number of bits. The image forming apparatus according to claim 2, wherein a printing start position for one pixel corresponding to the resolution information is designated.   The position information can specify the print start position of image data for one pixel corresponding to the resolution information from the larger print start positions as the resolution specified by the resolution information is lower. The image forming apparatus according to claim 4.   The said image processing part discriminate | determines the kind of said image data, and determines the resolution of the image printed based on the said image data based on the kind of said image data. Image forming apparatus.

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