JP2003060864A - Print controller, printer having the same and its control method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a printing apparatus having a toner saving mode,
With a simple configuration, even if the toner saving mode is set, the amount of toner consumed is reduced while maintaining the density change of an edge of an image having a sharp density such as a character line image. When the resolution of the printer engine in the main scanning direction is four times the resolution of the original image, one pixel of the original image corresponds to four pixels in the main scanning direction of the printer engine. The target pixel has a high density and is filled with four pixels, and when the toner saving mode is set, only three of the pixels are actually filled. When the density difference between the target pixel and the left pixel is equal to or more than a predetermined value and the density of the left pixel is low, the density difference between the left pixel and the left pixel is kept sharp. TBL2 is adopted as the filling pattern of. If the density of the right pixel of the target pixel is low, printing is performed using TBL3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print control device, a print device having the print control device, and a control method.

[0002]

2. Description of the Related Art Some printers that use toner in an electrophotographic system, such as a laser beam printer, have a function of reducing the amount of toner consumed.

Conventionally, to realize a toner saving function on the printer side for print data transmitted in binary from an external device, the print data is stored in a storage device and used as a toner saving pattern. It was possible to match and if the corresponding dot was black, mask it.

[0004]

However, in the above-mentioned prior art example, when the multi-valued monochrome data is transmitted from the external device, the toner-saving function is used in the route for converting the binary data and outputting it to the print engine. In order to realize the above, it is necessary to store the converted binary data in a storage device or to instantaneously perform image edge detection of multi-valued data and toner saving pattern matching. There is a problem in that the capacity of the storage device for storing pixels before or after the value conversion becomes large, and the configuration for controlling the toner saving function becomes very complicated.

Therefore, an object of the present invention is to realize a toner-saving function in a system for converting monochrome multi-valued data into binary data and printing it out by adding a simple circuit without changing the structure of the video generation unit. An object of the present invention is to provide a print control device capable of performing the printing.

[0006]

Toner images are printed by having a toner saving mode for reducing toner consumption and a normal mode, and controlling exposure time per pixel while scanning exposure with laser light. A printing control device in a printing device for sequentially inputting multi-valued pixel data, and determining whether or not the density of a target multi-valued pixel is abruptly changed between adjacent pixels; And the second determining means for determining which direction of the scanning direction of the pixel of interest is steep, when the first determining means determines that the density is sharply changing. When the toner mode is set, the exposure period for the pixel data of interest is set shorter than that in the non-toner saving mode, and based on the direction in which the density determined by the second determination means changes sharply. Exposure start timing And an adjusting means for adjusting the.

Further, according to the embodiment of the present invention,
A data storage means for storing the converted pixel and its left and right pixels by shifting the multi-valued video data from the video generation section; and a pattern generation means for generating a pattern number by decoding the data string of the plurality of pixels. It has a conversion table corresponding to the pattern number in each of the normal mode and the toner saving mode, which can be selected by the mode switching signal, and is constituted by the pattern conversion means which operates to refer to the conversion table data from the selected table number. To be done.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the embodiments, a laser beam printer will be described as an example of the printing method.

First, the configuration of the printing apparatus according to the embodiment will be described.

FIG. 8 is a cross-sectional view showing an internal structure of a laser beam printer (hereinafter, abbreviated as LBP) applied to this embodiment. This LBP is a character pattern from a data generation source (a host device such as a host computer). Can be registered and registration of fixing forms (form data).

In FIG. 1, reference numeral 740 denotes an LBP main body, which inputs and stores character information (character code) supplied from an externally connected host computer, form information, macro commands, and the like. A corresponding character pattern or form pattern is created in accordance with the above, and an image is formed on the recording paper which is a recording medium. 700 is an operation panel on which switches for operation and an LCD display are arranged, and 701 is an LBP 740.
This is a printer control unit that analyzes the overall control and the character information supplied from the host computer.
The control unit 701 mainly converts a character pattern corresponding to character information into a video signal to convert it to a laser driver 70.
Output to 2. The laser driver 702 is the semiconductor laser 7
03 is a circuit for driving the laser beam, and switches on / off the laser light 704 emitted from the semiconductor laser 703 according to the input video signal. The laser light 704 is swung in the left-right direction by the rotating polygon mirror 705 and scans the electrostatic drum 706. As a result, an electrostatic latent image such as a character pattern is formed on the electrostatic drum 706. The latent image is developed by the developing unit 707 around the electrostatic drum 706 and then transferred to the recording paper. A cut sheet is used as this recording sheet, and the cut sheet recording sheet is stored in a sheet cassette 708 mounted on the LBP 700, and is taken into the apparatus by a sheet feeding roller 709 and delivery rollers 77 and 711, and then the electrostatic drum 706. Supplied. And the developing device 7
The toner image adhered on the electrostatic drum 706 by 07 is transferred to the conveyed recording paper. After that, the recording paper is conveyed toward the fixing device 712, the toner is fixed,
Finally, it is discharged to the outside by the discharge roller 713.
In the embodiment, the resolution in the main scanning direction when printing is 2400 dpi and the resolution in the sub scanning direction is 600 dpi, but the invention is not limited to these resolutions.

FIG. 9 is a block diagram of the printer control unit 701. In the figure, 1 is a CPU that controls the entire apparatus, and 2 is a ROM that stores the operation processing procedure of the CPU 1 and font data. 3 is CPU
Reference numeral 1 denotes a RAM used as a work area, and reference numeral 4 denotes an operation panel including switches for giving various instructions and a liquid crystal display unit for displaying a simple message. The switch of the operation panel 4 is provided with a switch for setting whether or not the toner saving mode is set and the level of the toner saving mode. As a toner saving mode setting means, other than this, a method may be used in which information is specified to the host computer via the printer driver and the printer takes in the information before print output. Reference numeral 5 denotes an interface for connecting an external print data generation source, which can be connected to a host computer as shown in the drawing. Reference numeral 6 denotes an image memory for expanding image data to be printed, and in the embodiment, multi-valued data of 2 bits (0 to 3) per pixel is stored as described later. Reference numeral 7 is an image processing unit (details will be described with reference to FIG. 1) that sequentially reads the image data expanded in the image memory 6 and generates a video signal for printing, and 8 is a video signal from the image processing unit 7. Printer engine (Fig. 1)
It is an engine interface to output to.

Next, the image processing unit 7 in the embodiment will be described with reference to FIG.

In the figure, 101 is a video generator for reading image data from the image memory 6 and outputting multi-valued video data in pixel units in synchronization with a horizontal synchronizing signal from the engine unit, and 102 is a video generator. A multi-valued video data output by 101 is shifted by SVCK which is a synchronous clock of the video generation unit 101, and a data storage unit 103 that stores a total of 3 pixels including a converted pixel (a pixel of interest) and left and right (front and back) pixels thereof, 103. Is parallel data of 6-bit multi-valued video data of 3 pixels generated in the data storage unit 102 (2 bits × 3 pixels because 1 pixel corresponds to 2 bits in this example as shown in FIG. 5). By handling and decoding it, the pattern number (PAT_No) is converted into the pattern conversion unit 1 described later.
The pattern generation unit 104 outputs the pattern number 104 to the pattern number and the table number (TBL_No) output from the table generation unit (not shown) to determine the multi-value binary conversion data (CONV_D) in each of the normal mode and the toner saving mode.
T) generating pattern conversion unit 105 is VCLK (4 times cycle of SVCK) which is the original vibration of 4-bit multi-valued binary conversion data (this corresponds to 1 pixel of multi-valued video data).
P / S conversion output unit for outputting serial binary video data to the printer engine 9 through the engine interface 8 by synchronizing and parallel-to-serial conversion. Reference numeral 106 synchronizes with a horizontal synchronization signal from the engine unit. Then, it is a clock control unit that generates SVCK, which is a synchronous clock of the video generation unit 101, the data storage unit 102, and the pattern conversion unit 104, and a load signal (CONV_LD) of multilevel binary conversion data.

The table number input to the pattern conversion unit 104 may be a hard wire for each pattern number, or a register may be prepared for each pattern number and made variable by software.

2A and 2B are pattern conversion units 104.
Is a detailed view of 201, 202, 203, 2 in the figure.
In 04, the converted pixel (target pixel) is (0
0-, (01), (10), and (11) (all are binary representations), AND-OR 1, 2, 3, and 4 for selecting the table number in the Normal mode are shown.
205, 206, 207, and 208 are when the conversion pixels are (00), (01), (10), and (11), respectively,
AN for selecting the table number in toner saving mode
D-OR 5, 6, 7, and 8 are shown. 209,210
OR1, 2 and 211 for finally determining the table number of the normal mode and the toner saving mode respectively are selected by the toner saving mode switching signal, and SEL1 and 212 for selecting the table number of the corresponding mode are converted from the selected table number. SEL2 and 213 that refer to the table data are the conversion table data selected in SEL2 212.
Sampling at the timing of the TLD signal, CONV_
The flip-flop 1 outputs the DT to the P / S conversion output unit 105 (see FIG. 3 for detailed timing).

Next, the operation of the first embodiment of the present invention will be described based on the above configuration.

First, the video generation unit 101 generates multi-value video data (CVDO) in synchronization with SVCK during the effective print area of the paper, and this is generated in the data storage unit 102.
Then, a total of 3 pixels on the left and right of the converted pixel (target pixel) are shifted and stored. At this time,
DTLD which is an enable signal for bit shift is also
It goes without saying that it occurs only during the effective print area period of the paper.

Then, in the data storage unit 102, the VC
It is held in the order of DO → PAT_C → PAT_B → PAT_A. That is, as shown in FIG. 3, at the rising edge of a certain SVCK, the pixel (D
OT_C) is stored, PAT_A has a pixel immediately before the conversion pixel, that is, DOT_C.
The pixel (DOT_L) on the left side of the
C is the pixel after the conversion pixel, that is, DO
The pixel (DOT_R) on the right side of T_C is stored (dotted line portion in FIG. 3).

These PAT_A, PAT_B, PAT_C
Representing the 2-bit configuration as parallel data of 6 bits in total and decoding by the pattern generation unit 103, the converted pixel at the rising edge of a certain SVCK and the pixels on the left and right of the converted pixel are expressed in the form of a pattern number (PAT_No). Is possible.

This PAT_No is the pattern conversion unit 104.
Input to any one of the table numbers (TBL_No) that have been set for each PAT_No in advance.
However, in the present embodiment,
At this time, the gradation difference between the converted pixel and the left and right pixels thereof is detected from PAT_No. Then, the gradation difference 3 is left or right, that is, from the pixel (00) on the left side to the conversion pixel (11) or the conversion pixel (11).
By detecting the pixel (00) on the right side from, it is determined whether the converted pixel is in the image edge portion in either direction.

On the other hand, in the pattern conversion unit 104, in addition to the conversion table used in the normal mode, a conversion table used in the toner saving mode for suppressing the toner usage amount for trial printing is separately provided, and the toner saving In the case of PAT_No which is determined to be the image edge portion, the mode conversion table has a configuration in which dots in the direction of edge detection are left and the growth rate on the opposite side is weakened.

By doing so, when the gradation difference between the adjacent pixels is small, it is judged as the halftone portion, and the dots to be filled are thinned out, and conversely, when the gradation difference is large, the image edge portion (character Since it is determined that the line image is an edge) and dots are not thinned out, the result of the print output in the toner saving mode becomes considerably clear.

As an example, using the configuration of the conversion table as shown in FIG. 5, the conversion table is set for each PAT_No in the normal mode and the toner saving mode in the present embodiment (corresponding to toner saving (small) in FIGS. 7A to 7C). Are assigned, the results are as shown in FIGS. 7A to 7C. In the figure, the upper 2 bits of the 6 bits are the conversion pixel (target pixel)
And the pixels on both sides correspond to the lower 4 bits.

The laser beam printer according to the embodiment is equipped with an engine having a resolution of 2400 dpi in the scanning exposure direction of the main scanning direction (laser light),
An example of printing an original image of 600 dpi in the main scanning direction is shown. Therefore, one pixel of the original image is represented by four continuous minute areas in the main scanning direction with this engine. Now, let us consider a case where there is a pixel to be recorded at the highest density (TBL1 in the figure) and the toner saving mode is set at that time. At this time, it suffices to reduce one minute area to which the toner is to be attached, and the pattern in that case is TBL2 or T
It becomes BL3. In the embodiment, which of the TBLs 2 and 3 is adopted is determined according to which of the left and right directions of the converted pixel (target pixel) has 0.

Specifically, the pattern conversion unit 104 described above is used.
PAT_ determined to be an image edge part (layer difference 3)
When No is input, specifically, when a pattern such as ex1 in FIG. 6 is input, an edge (white pixel) is detected on the left side, so if the toner saving mode is set, the right side is detected. I tried to weaken the growth rate. This is Normal → T when PAT_No (56) in FIG. 7B.
BL1 corresponds to toner saving (small) → TBL2.

The reason for this is as shown in TBL2 of FIG.
The conversion pixel is (11), and among the four micro areas, the left three pixels are set to "1", so that ex in FIG.
This is because the density change between the left pixel and the converted pixel shown in 1 can be maintained in a steep state (density difference 3). This also makes it possible to simultaneously achieve the purpose of reducing the amount of toner consumed for the converted pixels.

When the toner saving mode is set higher, the TBL2 obtained by deleting one minute area from the TBL2 is used.
There are 4 and 5 but the edge is on the left side, so TBL
Adopt 4. Then, when the toner saving mode is further increased, it becomes TBL7. The TBL5 is used when the degree of edge is smaller than 3.

In the embodiment, the laser light is scanned and exposed on the photosensitive drum, and 1 pixel of the original image is 4 pixels for the printer engine (because the resolution in the main scanning direction is 4 times). Is recorded as. Therefore, adopting TBL2 in FIG. 5 means that the timing for releasing the exposure of one pixel of the original image is advanced and the exposure time is shortened as compared with the non-toner-saving mode (normal mode). To do. On the contrary, adopting the TBL3 is equivalent to shortening the exposure time, but equivalent to delaying the exposure timing.

On the other hand, when a pattern such as ex2 in FIG. 6 is input, an edge (conversion pixel (11) and right side (00) density difference 3) on the right side of the conversion pixel is detected. When the toner saving mode is set, the growth rate is decreased to the left. This is PAT_ in FIG. 7B.
No (49) Normal → TBL1, toner saving (small)
→ Corresponds to TBL3.

According to TBL3 in FIG. 5, since the three pixels on the right side of the converted pixel are "1", e in FIG.
As in x2, it is possible to reduce the toner consumption of the conversion pixel while maintaining the steep density difference from the right pixel.

As described above, the toner saving mode switching signal (TONER_SAV) is checked in advance to determine whether the toner saving mode is set.
By setting in the pattern conversion unit 104 according to E), the pattern conversion unit 104 sets P for each set mode.
The conversion table number corresponding to AT_No can be selected, and the conversion table data (CONV_D) referenced from it can be selected.
T) is output to the P / S conversion output unit 105.

In the P / S conversion output unit 105, CONV_
After synchronizing DT with VCLK, load it at the timing of CONV_LD and turn ON / O at a frequency four times that of SVCK.
It is output to the engine unit as serial binary video data (SVDO) that is FF. The engine part input 2
By driving the laser element 703 based on the value video data, the photosensitive drum is scanned and exposed.

FIG. 4 shows a program of the operation procedure in the above embodiment (CP of the printer controller of the printer device).
A program stored in the ROM 2 referred to by U) is shown as an example.

The operation processing procedure will be described below with reference to FIG.

First, in step S1, the pixel to be converted (2-bit multi-value video data) generated by the video generation unit and the pixel data on both sides thereof are input, and then in step S1.
Data for 3 pixels (total 6 bits) input in 2 is stored, and the data is decoded as parallel data to generate a pattern No.

In step S4, it is determined whether or not the current mode is the toner saving mode. If not, the process proceeds to step S5 and the normal conversion table is referred to, and the multi-value 2
Value conversion is performed, and the converted binary data is output to the printer engine as serial video data.

On the other hand, when it is determined that the toner saving mode is set, the process proceeds to step S6, the gradation difference between the converted pixel (target pixel) and the pixels on both sides thereof is detected, and whether the density is sharp or not is detected. Is determined in step S7. In the embodiment, since one pixel is represented by 2 bits, whether or not the density is steep is determined whether or not the difference between the values of the converted pixel and the adjacent pixel is 3. did. Of course, one pixel may have a bit number exceeding 2 bits. For example, in the case of 3 bits,
Although it has a value of 0 to 7, the threshold value for determining whether or not the density is steep in this case may be 7 or 6 which is the maximum. That is, the threshold value for determining whether or not one pixel is steep if one pixel has N bits may be set as appropriate.

If it is determined that the density is steep, the process proceeds to step S8, and it is determined in which of the left and right directions the edge (pixel with low density) is located. If it is determined that there is an edge on the left side, the process proceeds to step S9, and the conversion pixel (target pixel) is set on the right side so as to refer to the conversion table in which the growth rate is weakened. A table for weakening the growth rate on the right side of the converted pixel is as follows according to FIG.
The number of minute areas to which toner is attached is 4 → 3, 3 → 2,
There will be four types of 2 → 1, 1 → 0. This is the same in step S10 described below.

If it is determined that there is an edge on the right side, the process proceeds to step S10 to set the conversion pixel to the left side so as to refer to the conversion table in which the growth rate is weakened.

After that, the process proceeds to step S11, a process of generating serial binary data by referring to the determined table and outputting it to the printer engine is performed.

As described above, according to the present embodiment, the halftone portion or the image edge portion (the edge portion of the character / line image) is determined based on the gradation difference between the converted pixel and the pixel adjacent thereto. As a result, by preparing a conversion table different from the normal mode, there is an effect that the toner saving mode can be realized in the system that performs binary conversion of monochrome multi-valued data and prints it out.

The pattern conversion unit 104 uses the pattern number (PAT_NO) and the table number (TBL_N).
O) and a toner save (TONER_SAVE) signal, a binary pattern may be generated, and thus a lookup table may be used.

<Second Embodiment> In the second embodiment, in the above-described embodiment (first embodiment), one of the adjacent pixels on the left and right of the conversion pixel (11) is (0
0), that is, only when the gradation difference is 3, the conversion table for the toner saving mode is referred to in the toner saving mode, but even if the image edge is not determined, a certain condition (isolation Assuming that the pixel is not a point, the conversion pixel which is the pixel of interest is (10) or more, or (11) exists on the left and right even if it is (01). Is.

A concrete example of the conversion table allocation is shown in FIG. 7A.
Toner saving (large) at 7C.

According to the present embodiment, it is possible to save toner more than the first embodiment, and by using it in combination with the first embodiment, the image quality is prioritized even in the toner saving mode for the same user side. It is possible to select whether to prioritize the toner saving function for trial printing.

In each of the above first and second embodiments, the printer directly connected to the host computer has been described. However, the host computer may be connected to the host computer via a network, such as a copying machine or a facsimile machine. It may be applied to the printing section of.

[0048]

As described above, according to the present invention, in a printing apparatus having a toner-saving mode, even if the toner-saving mode is set with a simple structure, an image having a sharp density such as a character line drawing can be formed. It is possible to reduce the amount of toner consumption while maintaining the density change of the edge.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a print control device.

[FIG. 2A]

FIG. 2B is a detailed view of the pattern conversion unit 104.

FIG. 3 is a timing chart of the print control device.

FIG. 4 is a flowchart showing an operation processing procedure of the print control device.

FIG. 5 is a diagram showing a configuration of a conversion table and a table transition example for toner saving.

FIG. 6 is a diagram showing a pattern of multi-valued video data.

[FIG. 7A]

FIG. 7B]

FIG. 7C is an example of allocation of conversion tables for pattern Nos.

FIG. 8 is a cross-sectional structural diagram of the printer according to the embodiment.

9 is a block diagram of a printer control unit in FIG.

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Claims (7)

[Claims] 1. A toner-saving mode for reducing toner consumption and a normal mode are provided, and while scanning and exposing a laser beam,
A printing control device in a printing device that prints a gradation image by controlling an exposure time per pixel, in which multi-valued pixel data is sequentially input to a target multi-valued pixel,
First determining means for determining whether or not the density is abruptly changing between adjacent pixels, and when the first determining means determines that the density is abruptly changing, Second determination means for determining which direction of the scanning direction is steep, and when the toner saving mode is set, the exposure period for the pixel data of interest is set shorter than that in the non toner saving mode,
Further, the print control apparatus is provided with an adjusting unit that adjusts the exposure start timing based on the direction in which the density is abruptly changed, which is determined by the second determining unit. 2. The second determining means determines a direction in which a pixel having a density equal to or lower than a predetermined density with respect to the density of the target pixel data, and the adjusting means determines an exposure start timing corresponding to the target pixel data. The print control device according to claim 1, wherein the print control device is adjusted in a direction in which it is determined that there is a pixel having a density equal to or lower than the predetermined density. 3. The adjusting means includes a look-up table for inputting a signal indicating the degree of the toner-saving mode, multi-valued pixel data of interest and multi-valued pixel data on both sides thereof as addresses, and an output from the look-up table. 3. The print control apparatus according to claim 1, further comprising a unit that converts data into serial data. 4. A printing apparatus comprising the print control apparatus according to claim 1. 5. A toner-saving mode for reducing toner consumption and a normal mode are provided, and while scanning and exposing a laser beam,
A method for controlling a print control device in a printing device that prints a gradation image by controlling an exposure time per pixel, comprising sequentially inputting multivalued pixel data,
A first determination step of determining whether or not the density is abruptly changed between adjacent pixels, and if it is determined in the first determination step that the density is abruptly changed, The second determination step of determining which direction of the scanning direction is steep, and when the toner saving mode is set, the exposure period for the pixel data of interest is set shorter than that in the non toner saving mode,
And a control step of adjusting the exposure start timing based on the direction in which the density is abruptly changed, which is determined by the second determination step. 6. A printing apparatus which converts a value of multi-valued pixel data into a serial signal, prints by scanning and exposing a laser beam generated based on the serial signal, and has a toner saving mode, A conversion table for generating a binary pattern by inputting a mode identification signal indicating a toner saving mode or a normal mode and a signal indicating a pattern number, the pixel of interest data, and a plurality of pixels on both sides of the pixel of interest. Pattern number generating means for generating the pattern number corresponding to the pixel of interest based on the value pixel data, and supplying the pattern number generated by the pattern number generating means and the identification signal to the conversion table. A printing apparatus, wherein the binary pattern obtained in step 1 is serially converted, and scanning exposure of laser light is performed based on the serial signal. 7. The pattern number generated by the pattern number generating means is the pixel data of interest and the pixel data on both sides, and the conversion table indicates that the identification information indicates the toner saving mode, and the difference from the pixel of interest. Is larger than a predetermined value, and when there is adjacent pixel data with low density, a pattern that weakens the growth rate is registered in a direction opposite to the direction in which the adjacent pixel with low density exists. The printing device according to claim 6.