JP6750490B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

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

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 the 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 a character image is processed at 600 dpi-3bit (high resolution/low gradation). Describes that an image is formed at an optimum resolution and gradation according to the type of image by processing at 300 dpi-6 bit (low resolution/high gradation).

Further, for example, in Patent Document 2, a print position and a print pulse width are determined depending on the presence or absence of printing of image data of an image group in which a plurality of consecutive pixels is one pixel, and the PWM circuit is determined by the determined print position and pulse width. It is described that by generating a pulse signal by the method, it is possible to form a high quality image with high resolution.

JP, 7-256936, A JP, 2003-136781, A

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

Further, Patent Document 2 does not describe switching of a plurality of resolutions. Further, although the print position in the image forming area of 1 pixel can be controlled, the print position is controlled according to the presence/absence of the printing of the image data, so that the fine position control cannot be performed.

An object of the present invention is to make it possible to more finely control the resolution of an image to be printed and the print start position of each pixel.

In order to solve the above problems, the invention described in claim 1 is
An image forming apparatus including a print unit that prints an image on a sheet based on image data,
Resolution information that specifies the resolution of a pixel unit of an image to be printed based on the image data by the number of consecutive 1s or 0s, and a print start position in the print area of each pixel of the image unit is specified in a pixel unit. An image processing unit that generates position information and transmits the resolution information, the position information, and the image data in association with each other to the printing 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 described in claim 2 is the same as the invention described in claim 1,
The resolution information indicates that the higher the number of consecutive 1s or 0s, the lower the resolution.

The invention described in claim 3 is the same as the invention described in claim 2,
One bit of the resolution information corresponds to image data of a predetermined number of bits, and the image data of the number of bits obtained by multiplying the number of consecutive 1s or 0s of the resolution information by the predetermined number of bits corresponds to one pixel. It is combined as image data to express the gradation of one pixel corresponding to the resolution information.

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

The invention described in claim 5 is the same as the invention described in claim 4,
As for the position information, the lower the resolution specified by the resolution information is, the more the print start position can be specified, and the print start position of the image data of one pixel corresponding to the resolution information can be specified. ..

The invention according to claim 6 is the invention according to any one of claims 1 to 5,
The image processing unit determines the type of the image data, and determines the 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, the resolution of an image to be printed and the print start position of each pixel can be controlled more finely.

FIG. 3 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 transmitting image data, resolution information, and position information from the image processing unit of FIG. 2 to a 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. Is. FIG. 6 is a diagram schematically showing an image edge printed at a resolution of 1200 dpi with the print start position being right aligned. FIG. 5 is a diagram schematically showing image edges printed at a print start position from the top at right resolution 1, right alignment 2, right alignment 3, and right alignment 4 at a resolution of 600 dpi.

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 example.

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 out the system programs and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operation of each part of the printer 100 according to the expanded programs.

The storage unit 12 is composed of 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 under the control of 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 (not shown), performs RIP processing (rasterization), and outputs the image data to the image processing unit 15.

The image processing unit 15 performs various image processing such as color conversion on the input image data.
Further, the image processing unit 15 determines the type of 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 image data. The resolution of the image to be processed is determined, and resolution information that specifies the determined resolution in pixel units 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 resolution information specifying a high resolution (2400 dpi or 1200 dpi) is generated. When the type of image data is graphic data or photographic data, it cannot be properly expressed when the number of gradations is small, so resolution information designating a low resolution (600 dpi) is generated. Here, in the present embodiment, the input image data has 8 bit 256 gradations, and is converted into 2 bit 4 gradations when the resolution is 2400 dpi and 4 bit 16 gradations 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 the surrounding pixels included in the attribute information of the image data, and determines the determined print start position. Generate the specified location information.
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 each other, and synchronizes them with each other. It transmits to the PWM circuit 161. In the present embodiment, YMCK image data of 2 bits each, 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 each synchronization signal.

FIG. 3 shows a timing chart when transmitting the image data, the resolution information, and the position information from the image processing unit 15 to the PWM circuit 161.
As shown in FIG. 3, the resolution information specifies the resolution of an image to be printed based on the image data being transmitted, by a continuous number of 1 or 0. For example, if 1 or 0 is once, 2400 dpi is specified, if it continues twice, 1200 dpi is specified, and if it continues 4 times, 600 dpi is specified. As described above, since the resolution information specifies the resolution of the image to be printed by the continuous number of 1 or 0, it is possible to control the resolution and gradation more finely than in the past.

As described above, 1 bit of resolution information corresponds to 2 bits of image data, and image data of 1 pixel is obtained by multiplying 2 bits by the number (bit number) in which 1 or 0 of resolution information is continuous. To express the gradation of 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.
In addition, 1-bit position information corresponds to 1-bit resolution information, and the position information is converted into resolution information by the bit number data obtained by multiplying the 1-bit 0 number of resolution information (bit number) by 1 bit. The print start position corresponding to one pixel is designated. 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 print region of one pixel of the image to be printed differs depending on the resolution. In the case of high resolution, the width of the 1-pixel printing area becomes small, and in the case of low resolution, the width of the 1-pixel printing area becomes large. For example, the width of a 1-pixel printing area with a resolution of 1200 dpi is twice the width of 2400 dpi, and the width of a 1-pixel printing area with a resolution of 600 dpi is 4 times the 2400 dpi. That is, in the case of high resolution, since the width of the print area of 1 pixel is small, it is not necessary to perform fine control of the print start position. Similarly, if the print start position is controlled, the 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 centered print start position is specified using the position information of 1 bit per pixel. For example, the centering (see FIG. 4A) is designated by the position information “0”.
When the resolution is 1200 dpi, as described above, the print start position of any one of the center alignment, the left alignment, and the right alignment is specified by using the position information of 1 pixel and 2 bits. For example, the position information "00" specifies centering, "01" specifies left alignment, and "10" specifies right alignment (see FIG. 4B).
When the resolution is 600 dpi, the print start position is specified using the position information of 1 pixel 4 bits as described above. For example, the position information "0000" specifies the center alignment, "0001" to "0100" specifies the left alignment 1 to 4, and "1001" to "1100" specifies the 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 transport path (not shown), and the like. Printing is performed by the electrophotographic method based on the image data, the resolution information, and the position information that are stored.
That is, when the image data, the resolution information, and the 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 for one pixel and the position information. To do. Then, 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, irradiates the laser light from the LD 163 onto the photosensitive drum, and performs exposure. Form a latent image. After that, the developing unit 165 transfers the toner image formed by spraying toner onto the printing paper to perform printing.

FIG. 5 shows an image edge printed at a resolution of 1200 dpi with the print start position being right aligned. FIG. 6 schematically shows image edges printed at a print start position at a resolution of 600 dpi from right to right 1, right 2, 2, right 3, and right 4. As shown in FIG. 6, in 600 dpi, the print start position can be set in more detail for each pixel than in 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 copies can be printed, the image edge in the sub-scanning direction can be smoothly expressed.

As described above, according to the image processing unit 15 of the printer 100, the resolution information that specifies the resolution of an image to be printed based on the image data in units of one pixel by the number of consecutive 1s or 0s, and the printing of each pixel. Position information that specifies the print start position in the area in pixel units is generated, and the resolution information, the position information, and the image data are associated and transmitted to the printing unit 16.
Therefore, 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 higher the number of consecutive 1s or 0s, the lower the resolution. One bit of the resolution information corresponds to a predetermined number of bits of image data, and 1 or 0 of the resolution information is consecutive. The image data of the number of bits obtained by multiplying the number of bits by a predetermined number of bits is combined as the image data of one pixel to express the gradation of one pixel corresponding to the resolution information. Therefore, it is possible to express a pixel with a lower resolution with a higher gradation.

Further, 1 bit of the resolution information corresponds to a predetermined number of bits of position information, and the position information is the resolution information based on the number of bits of data obtained by multiplying the number of consecutive 1s or 0s of the resolution information by the predetermined number of bits. The print start position for one pixel corresponding to is designated. Therefore, the lower the resolution specified by the resolution information, the more the print start position can be specified, and the print start position of the image data of one pixel corresponding to the resolution information can be specified.

Further, the image processing unit 15 determines the type of image data, and determines the resolution of the 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 according to the type of image data.

It should be noted 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-described embodiment, the case where the image forming apparatus of the present invention is applied to the electrophotographic printer is described as an example, but the present invention is not limited to this. For example, another printing printer such as an inkjet printer or It may be applied to a copying machine or the like.

Further, 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 of the program according to the present invention is disclosed, but the invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. Further, a carrier wave is also applied as a medium for providing the data of the program according to the present invention via a communication line.

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

100 printer 11 overall control unit 12 storage unit 13 display unit 14 data input unit 15 image processing unit 16 printing unit

Claims (6)

An image forming apparatus including a print unit that prints an image on a sheet based on image data,
Resolution information that specifies the resolution of a pixel unit of an image to be printed based on the image data by the number of consecutive 1s or 0s, and a print start position in the print area of each pixel of the image unit is specified in a pixel unit. An image processing unit that generates position information and transmits the resolution information, the position information, and the image data in association with each other to the printing unit;
The print unit is an 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 the image data of the number of bits obtained by multiplying the number of consecutive 1s or 0s 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 data is combined as image data to express a gradation of one pixel corresponding to the resolution information. Position information of a predetermined number of bits corresponds to 1 bit of the resolution information, and the position information is represented by data of a number of bits obtained by multiplying the predetermined number of bits by the number of consecutive 1s or 0s of the resolution information. The image forming apparatus according to claim 2, wherein a print start position for one pixel corresponding to the resolution information is designated. As for the position information, the lower the resolution specified by the resolution information is, the more the print start position can be specified, and the print start position of the image data of one pixel corresponding to the resolution information can be specified. The image forming apparatus according to claim 4. 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. Image forming apparatus.

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