JPH04144479A - Graphic output device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphic output device that performs anti-aliasing processing to remove jagged edges of an output image. The present invention relates to a graphic output device that corrects the brightness value of anti-aliasing processing or the result of density modulation processing in accordance with.

[Conventional technology]

When a -component developer is used in the development process of an electrophotographic process, toner particle size selection occurs during a series of development cycles, and generally, as toner is consumed, toner particles with large particle sizes remain. It becomes easier to do. As a result, there is a possibility that the development characteristics vary and the effect of the image output due to the anti-aliasing process is diminished.

FIG. 25 shows the image density versus surface potential of the photoreceptor when one-component magnetic toner is used. In the figure, the solid line indicates the initial state or the state where there is a lot of toner in the hopper after toner replenishment, that is, the state where there is a lot of toner in the hopper. , when the toner particle size distribution is small, and as the toner in the hopper decreases with development processing and the particle size distribution increases, the development characteristic γ changes as shown by the arrow, and when the toner reaches the end, it becomes like the dotted line. .

As a result, it becomes difficult to develop the low potential area, pixels whose density has been modulated to a low density are not printed, and jaggedness becomes more noticeable compared to the initial stage (after toner replenishment).

In FIG. 25, the case where a -component magnetic toner is used is explained, but in FIG. 26, a one-component development method using a non-magnetic toner is explained.

FIG. 26 shows the image density versus surface potential of the photoreceptor when using a single-component non-magnetic toner.
When the solid line is initialized, there is a lot of toner in the pump after toner is replenished.

From this state, when the toner is consumed and the toner in the hopper decreases by repeating the development process, the development characteristic T changes in the direction of the arrow, and becomes as shown by the dotted line when the toner is used up.

When the toner in the hopper is supplied to the surface of the developing roller and the developing process is performed, an elastic member is generally pressed against the surface of the roller as a supplying means to uniformly charge the toner.
This is because the layer is thinned, and this method is simple and extremely effective, but on the other hand, particle size selection occurs when the toner passes through the elastic member, and particles with small sizes are This occurs because the toner particle size inside the pump gradually increases as the toner is consumed due to passing through the toner first, and as a result, the amount of charge (q/m) of the toner decreases (generally, in the case of triboelectric charging , charge amount per unit volume (q
When the composition is the same, the larger the particle size, the smaller the toner adhesion to the photoreceptor.
The smaller the , ), the more).

In order to prevent the disadvantages described in item 2 above, it is possible to use toner with a uniform particle size, but a developer with a uniform particle size for all toners is expensive to manufacture and difficult to put into practical use, so it is currently not possible. At present, it is necessary to use toner having a plurality of particle size distributions.

In order to use toner having a plurality of particle size distributions without any adverse effects, it is necessary to monitor the selection of toner particle size during a series of development cycles and correct it by applying feedback.

As a correction method, there is a method in which an image (test pattern) is created on a photoreceptor in advance and correction is performed based on the image information.

[Problem to be solved by the invention]

However, the conventional method described above requires a reading device, memory, arithmetic device, etc. to obtain image information of the image (test pattern) and process the information, and the device itself is expensive. The problem is that it becomes complicated.

The present invention has been made in view of the above, and it is an object of the present invention to realize anti-aliasing brightness modulation processing that takes into account changes in development characteristics due to changes in toner remaining amount and particle size, at low cost and with a simple configuration. purpose.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an anti-aliasing processing means for smoothly expressing jagged edges (aliases) of an output image, and an anti-aliasing processing means that converts image data subjected to anti-aliasing processing into a series of electronic A graphic output device comprising an image output means for outputting using a photographic process, a detection means for detecting a residual level of a developer used in development processing in the electrophotographic process; The present invention provides a graphic output device including a correction means for correcting the luminance value of the anti-aliasing process or the result of the density modulation process according to the level.

Further, the present invention provides a graphic output device in which the developer is a one-component developer and is provided with a correction means for correcting the brightness value or density modulation processing result of the anti-aliasing processing according to the residual level of the developer in the hopper. It is.

Further, it is preferable that the detection means converts the rotational torque of an agitator in the hopper into an electric signal to detect the residual level of the developer.

Further, it is preferable that the detection means detects the residual level of the developer by monitoring the ON/OFF signal of the ultrasonic vibration element.

[For production]

The graphic output device of the present invention detects the remaining amount of toner based on the relationship between the amount of toner remaining in the hopper and the change in development characteristics associated with particle size selection, and performs anti-aliasing according to the detected detection output level. Correct the relationship between level and brightness modulation conditions.

〔Example〕

Hereinafter, one embodiment of the graphic output device of the present invention will be described based on the drawings. ■ Schematic configuration of image forming system ■ Anti-aliasing processing ■ Configuration and operation of PDL controller ■ Configuration of image processing device ■ Multilevel color laser printer A detailed explanation will be given in the following order: configuration, configuration and operation of the developing section of the multivalued color laser printer; (1) multivalued drive of the driver;

■Schematic configuration of image forming system The image forming system of this embodiment uses a page description language (page description language) output from DTP (desk top publishing).
Page Description Language
This configuration allows image formation of both image information, including vector data written in the PDL language (hereinafter referred to as PDL language) and image images read by an image reading device.

The configuration of the image forming system of this embodiment will be described below with reference to FIG.

The image forming system includes a host computer 100 that creates a document written in PDL language (Postscript language is used in this embodiment);
A PDL controller (the anti-aliasing processing of the present invention) that applies anti-aliasing processing to the incoming PDL language sent page by page from equipment) 200
an image reading device 300 that reads image information through an optical system unit; and an image processing device that inputs an image output from the PDL controller 200 or the image reading device 300 and performs image processing (details will be described later). device 400, and a multivalued color laser printer 5 that prints multivalued image data output by the image processing device 400.
00, PDL controller 200, and image reading device 3
00, a system control unit 600 that controls the image processing device 400 and the multivalued color laser printer 500;
It consists of

■Anti-aliasing processing The following methods are known as anti-aliasing processing methods.

i, Uniform averaging method 110 weighting is an averaging method iii, Convolution integral method Each of the above methods will be explained in turn.

i, Uniform averaging method The uniform averaging method reduces each pixel to NXM (N, M
is a natural number), performs rask calculation at high resolution, and then calculates the brightness of each pixel by taking the average of NXM sub-pixels. Figure 2 (a), (
Anti-aliasing processing using the uniform averaging method will be specifically explained with reference to b).

If the edge of the image is over a certain pixel (here, the image is connected to the bottom right of the diagonal line),
When anti-aliasing processing is not performed, the same figure (a)
), the brightness kid of this pixel is the highest brightness of the gradation that can be displayed (for example, for 256 gradations, kid=
255) is assigned. N=M= for this pixel
When performing anti-aliasing processing using the uniform averaging method of 7, pixels are divided into 7
The image is divided into 7 subpixels and the number of subpixels covered by the image is counted. The count number (28) is 1
The maximum brightness (255) is divided by the total number of sub-pixels in the pixel (49 in this case) and normalized (averaged), and then multiplied by the maximum brightness (255) to calculate the brightness of that pixel. In this way, in the uniform averaging method, the brightness of each pixel is determined by taking into consideration how the image covers each pixel.

110 Weighting is an averaging method The weighting and averaging method is a partial modification of the uniform averaging method. In contrast, the weighted averaging method assigns a weight to each subpixel, and the brightness of that subpixel is determined based on which subpixel the image falls on. The effects are different. Note that the weight at this time is given using a filter.

Referring to Figures 3(a) and (b), an example is shown in which the same image data as in Figure 2(a) is weighted using the same dividing method (N=M=7) and the averaging method. .

FIG. 3(a) shows a filter (here, cone f
ilter ), and the corresponding sub-pixel is given the same weight as this characteristic. For example, the weight of the upper right corner subpixel is 2. When an image is applied to each subpixel, the weight value given by the filter characteristics becomes the count value of that subpixel. The same figure (b
) shows the display pattern of the image changed depending on the weight of the sub-pixels. In this case, the number of weighted subpixels in the image is 199. This value is averaged by dividing it by the sum of the filter values (in this case, 336) corresponding to the uniform averaging, and multiplied by the maximum brightness to calculate the brightness of this pixel. In addition, as a filter, see Figure 4 (
Filters shown in a), (b), (C), and (d) are known.

iii. Convolution integral method The convolution integral method is a method that also refers to the appearance of surrounding pixels when determining the brightness of one pixel. That is, the area around one pixel whose brightness is to be determined is N
' The corresponding pixel is indicated by 51.

The image continues below and to the right of the diagonal line, and the subpixels painted black are the subpixels that are counted.

Each pixel is divided into 4x4. Therefore, in this case, a 12×12 filter will be used. This method has the effect of removing high frequency components contained in a vector image.

On the other hand, a publishing system using a personal computer,
With the spread of so-called DTP (desk top publishing), systems for printing vector images, such as those used in computer graphics, have become widely used. A typical example of this is a system using Adohi's Post Script. PostScript belongs to the language genre of page description languages, and is a form that describes the contents of a single document, including the text (letter part), graphics, and their arrangement and appearance. It is a programming language for writing, and in such systems, vector fonts are used as character fonts. Therefore, even if characters are scaled, printing quality can be significantly improved compared to systems that use bitmap fonts (for example, conventional word processors), and character fonts and graphics can be It has the advantage of being able to print a mixture of images.

However, according to the conventional anti-aliasing processing method and its device, one pixel is divided into a plurality of sub-pixels (for example, 49 sub-pixels), the number of filled sub-pixels is counted, and the area ratio ( There is a problem in that it takes time to calculate the area ratio (brightness), which hinders improvement in display speed or printing speed. In particular, the convolution method requires a large amount of calculation and affects multiple pixels, so it is difficult to improve processing speed.

In view of the above, an anti-aliasing method has also been proposed that calculates the area ratio at high speed without dividing subpixels or counting the number of filled pixels.

iv. Method for obtaining approximate area ratio of edge pixels This anti-aliasing processing method calculates the presence or absence of intersections between vector data and a predetermined group of straight lines when edge pixels are divided by a predetermined group of straight lines, and the type of edge. Based on this, an approximate area ratio of the edge pixel is obtained. Below, Figure 6 (
With reference to a) to (f), a method for obtaining an approximate area ratio from the presence or absence of an intersection and the type of edge will be described in detail.

A straight line L1 given by vector data (hereinafter referred to as vector straight line L1) and each line y in the sub-scanning direction y
. +y++yz is the intersection point X, as shown in FIG. 6(a). + X l + X 2, the equation of this vector straight line L1 is, for example,
o)+(x++y+) using the following equation (1).

X + -X.

On the other hand, focusing on the pixel P, a new x'y" coordinate system is set, and the pixel P is connected to the straight line I, as shown in FIG.
! , I, lz, I! z, i4. is, lb,
It is divided by eight straight lines l'r and na (hereinafter referred to as dividing straight lines). Here, the equations of each straight line are expressed by the following equations (3) to (10), respectively.

■ Dividing straight line p, +: x = O---------(
3) j2z: x=1/3 −・−(4) J23
: X = 2 / 3 ------- (5) i!
, 4 :X=1 ・------・ (6) Es
: y=o −−−−・−・ (7) Eb:y=
1/3 -...-111 (8) i 7: y =
2/3 ---------- (9)! ! ,a:
y = 1 −−−−−−−−00) Also, the equation of the vector straight line L1 obtained using the above equation (1) is y−−(1/3)x+ (7/6) −−−−( 2)
Assuming that, dividing straight lines Ill, p2, which divide this vector straight line L1 and pixel P, p2. z3. p4.
J2s.

1! ,b,I! , 'r, and f18 are as shown in the following table.

Table Here, the range of
The intersection within the range of this pixel P is the division straight line 1
．． ．． 1. ．． 1. There are three dividing straight lines. Conversely, within the range of this pixel P, the three dividing straight lines 123. R,4,1
The equation of a vector straight line that has an intersection only with 8 is, if the intersection points are A and B as shown in Figure 6 (C), the coordinates of the intersection A are (1/3<x'≦2/3.y' -1
) The coordinates of the intersection B always pass through the range (x'-L 2/3<y'<1). Therefore, the three dividing straight lines A3. ! 4. The area ratios of pixels P divided by vector straight lines that intersect only with j2e are close to each other. The area ratio of the pixel P divided by the set of vector straight lines indicates a similar area ratio within a predetermined range. Therefore, the vector straight line and the dividing straight line 121+ j2 z, Q 3. N4. j2
s-ni. , x, ,p, can be approximated to one area ratio.

Therefore, in this anti-aliasing processing method, a set of vector straight lines is created based on the intersection information and edge information indicating which edge is on the left or right, and an approximate area ratio is calculated for each set in advance. For example, a LookUp Table (LUT) consisting of intersection information, edge information, and approximate area ratios as shown in FIG. 6(d) is created. Then, when performing anti-aliasing processing, instead of performing subpixel division and calculating the area ratio of edge pixels, the corresponding approximate area ratio is input from the LUT based on the intersection information and edge information. The output of the edge pixels is adjusted accordingly.

In the LUT shown in FIG. 6(d), the edge information flag indicates a left edge when the left edge flag is -1 and the right edge flag is -0, and indicates a right edge when the left edge flag is -0 and the right edge flag is -1. .

Also, when the left edge flag - right edge flag - 1,
It represents a vertex as shown in (e) of the same figure, and the division straight line flag -
1, each dividing line p,, p2...
18 and the vector straight line intersect (that is, there is an intersection). Figure (8) shows a straight line that can be considered under the conditions of LUT data D1.
1 also includes information on the approximate area ratio of the shaded area shown in FIG. 1(e). Similarly, the straight line that can be considered under the conditions of the data D2 of the LUT is shown in Fig. 3), and the data D2 includes information about the approximate area ratio of the shaded portion shown in Fig. 3(f). Therefore, for example, when calculating the area ratio of the vector straight line shown in FIG. １、２□、・・・・・・! 6, then determine whether the edge is a left edge or a right edge using the edge information determined by the PDL specifications, and based on these intersection information and edge information, calculate the corresponding approximate area ratio from the LUT. get.

■The configuration and operation of the PDL controller is shown in Figure 7.
The configuration of the DL controller 200 is shown, and includes a receiving device 201 that receives the PDL language sent from the POS 1 computer 100, a CPU 202 that performs storage control of the PDL language received by the receiving device 201, and executes anti-aliasing processing. An internal system bus 203, a RAM 204 that stores the PDL language transferred from the receiving device 201 via the internal system bus 203, a ROM 205 that stores an anti-aliasing program, etc., and multi-value R, G, which has been subjected to anti-aliasing processing. A page memory 206 that stores B image data, a transmitting device 207 that transfers the R, G, and B image data stored in the page memory 206 to the image processing device 400, and an I10 device that performs transmission and reception with the system control unit 600. It consists of

Here, the CPU 202 receives the P received by the receiving device 201.
The DL language is transferred to the RAM 204 through the internal system J and the bus 203 according to the program stored in the ROM 205.
Store in. After that, when the PDL language for one page is received and stored in the RAM 204, the graphic elements in the RAM 204 are subjected to an anti-aliasing processing method based on the flowchart described later, and a multivalued R, G, B image is generated. The data is stored in the plain memory section of the page memory 206 (the page memory 206 consists of plain memory sections for R, G, and B, and a feature information memory section).

The data in the page memory 206 is then transferred to the transmitter 2
07 to the image processing device 400.

The operation of the PDL controller 200 will be described below with reference to FIGS. 8(a) and 8(b).

FIG. 8(a) shows a flowchart of the processing performed by the CPU 202. As described above, the PDL controller 200 performs anti-aliasing processing on the PDL language sent page by page from the host computer 100, and generates three-color images of red (R), green (G), and blue (B). Expand to.

In the PDL language, graphics and characters are all described using vector data, and as the name "page description language" indicates, image information is processed in units of pages. Furthermore, one page is made up of at least one path, with each path being made up of one or more elements (graphic elements and character elements).

First, when PDL language is input, it is determined whether the element is a curved vector, and if it is a curved vector, it is approximated to a straight line vector and registered as a straight line element (line) in the work area. This is done for all graphic and character elements within one path, and linear elements are registered in the work area for each path (process 1).

Then, the straight line elements of the work area registered in this path unit are sorted by the starting X coordinate of the straight line (processing 2)
.

Next, in process 3, while updating the X coordinate one by one,
Performs filling processing using scanning lines. For example, in Figure 8 (
When performing the path filling process shown in b), the element on the side across which the scanning line yc to be processed and the real value of the X coordinate across the scanning line yc (XI shown in FIG. 8(b))
X2 X3 X4) and AET (Active Edge)
eTable: A table for recording the X coordinate of an edge portion appearing on a scanning line).

Here, the order of the elements registered in the work area is the order in which they were registered in process 1, so they are not necessarily registered in order of decreasing X coordinate across the scanning line yc. For example, in process 1, if a straight line element passing through scanning line yc and X3 in FIG. 8(b) is processed first, be registered first. Therefore, after the AET is registered, the elements on each side within the AET are sorted in descending order of X coordinate. Then, the first two elements of the AET are paired and the space between them is filled in (filling process using scanning lines). Anti-aliasing processing is achieved by adjusting the density and brightness of pixels in the edge portion in accordance with the approximate area ratio in this filling processing. Then, remove the processed edge from the AET and update the scanline (X
coordinates) and repeats the same process until all edges in the AET are processed, in other words, until all elements in one path are processed.

The operations of process 1, process 2, and process 3 described above are executed pass by pass, and repeated until all passes for one page are completed.

Next, the anti-aliasing process executed during the scan line filling process of process 3 described above will be described in detail.

Here, for example, in process 1 of FIG. 8(a),
), this figure has the following elements.

(B) Five line vectors AB, BC, CD, DE, EA (represented by real numbers) (II) Color and brightness values inside the figure This figure is created as shown in Figure 9(b) by the above-mentioned operation. The image is divided into seven straight line vectors (expressed as real numbers) extending in the main scanning direction. At this time, in this embodiment, the following information is added to the starting points and ending points of the seven straight line vectors.

That is, (c) Starting point coordinate value (real number expression) of the vector element ((a) above) that constitutes the starting point and ending point of the straight line vector (d) Slope information (*) of the vector element that constitutes the starting point and ending point of the straight line vector ) Characteristic information of the starting point and ending point of a straight line vector (right edge, left edge, apex of a figure, line of one dot or less, intersection of straight lines, etc.).

The operation of the PDL controller of the graphic output device according to the present invention that executes anti-aliasing processing will be explained using the flowchart of FIG. 8(C).

The subpixel filling process (S401) is performed as described in (c) above.
Based on the information in (d) and (d), the filling process is executed for each subpixel. FIG. 9(b) shows the processing results for scanning line ym when one pixel is divided into 3×3.

The Zabvixel filling process in step 5401 repeats the same process for all vectors that cross that side (S402).

In the brightness determination process (S403), the above-described anti-aliasing filter is applied sequentially to the first pixel of the scanning line, and the approximate area ratio of each pixel is calculated to be ≦1.

Here, as an anti-aliasing process, for example, a uniform averaging method filter (FIG. 9(d)) is used as shown in FIG.
) is shown in FIG. 9(e).

Incidentally, if you perform filling processing for each line without performing anti-aliasing processing, Xn, X n 4-1
The approximate area ratios of the pixels of are both 1, and as a result, aliasing (jaggies) occurs.

Next, in the overwriting process (S404), the luminance value kr (red) for each color of the figure,
Calculate kg (green) and kb (blue).

The calculation formula is shown below.

kr - (red brightness value of the figure given in (b) above) x
+ (luminance value of red previously painted) × (lk) kg - (luminance value of green of the figure given in (IT) above)
x + (previously painted green brightness value) x (1-k) kb - (blue brightness value of the figure given by (0) above) x
+ (luminance value of previously painted blue) x (1-k) Note that the brightness values of previously painted red, green, and blue are referred to data in the plain memory section of the page memory 206.

After the overwriting process (S404), the toner remaining amount correction process (S407) is performed such that the correction near area ratio hk,
, (refer to the section ``Configuration of a multi-valued color laser printer (configuration and operation of the developing section of a multi-valued color laser printer)'' described later), the brightness of each color of the figure obtained in the overwriting process (S404) Value kr (red), kg (
(green) and kb (blue) using the following procedure.

Step 1: kr 1=mXkr/maximum brightness value kgl=
mXkg/maximum brightness value kbl=mXkb/maximum brightness value Procedure 2: Find the stage number i that is close to the IDR and value of krl, kgl, and kbl.

Step 3: Corrected approximate area ratio hk referenced by j and i,
The brightness correction process takes into account the remaining amount of toner kr2-(1+hkJ,)Xkr kg2-(1+hkJ1)Xkg kb2=(1+hkJ1)Xkb using

In the frame memory drawing process (S405), the above kr, k
The luminance value of gXkb is stored in each plane memory section of the page memory 206, and the characteristic information of each pixel is stored in the page memory 20.
The information is stored in the characteristic information storage memory section of No. 6.

The CPU 202 repeats the above processing up to the last pixel of the scanning line (y coordinate) (S406). In addition, the contents of the starting point coordinate values of the vector elements forming the starting point and ending point of the straight line vector in (c) are also updated using the slope information of the back 1 to 3 elements forming the starting point and ending point of the straight line vector in (d) above. To go.

Here, if the red (maximum brightness: 255) figure shown in Figure 9(a) is drawn on a white background (maximum brightness: 255), the approximate area ratio of the figure in Figure 9(a) As shown in FIG. 10, the plane memory section in the page memory 206 has R as shown in FIGS. 11(a), (b), and (C).
, G, B image data are stored.

The CPU 202 repeats the above processing up to the last pixel of the scanning line (y coordinate), and at the same time updates the contents of (c) above with the information of (d) above. The approximate area ratio of the figure in FIG. 9(a) obtained by the anti-aliasing process in this way has a value as shown in FIG. 10.

Here, if the figure in FIG. 9(a) has a white background color (
The figure color is red (maximum brightness: 25) on top of (maximum brightness: 255)
5), the approximate area ratio k (10th
(see figure), the brightness value for each color of the figure is (red), 9
(green) and Kb (blue) are obtained based on the following formula.

K, -KR,Xk + KR2X(1-k)K9
=KGIXk +KGZX(1-k)Kb-Ku
+Xk + KB□X(1-k) However, KRI
, KGI, and KRI each indicate the brightness value of the color (red, green, and blue, respectively) of the figure given in (b) above, and KR
2. KG□, KB□ indicate the brightness value of each previously painted color. In addition, KRZ, KO2, and KBZ are page memories 206
The data in each plane memory section corresponding to R, G, and B is referred to.

The brightness value Kr1K9+ obtained in this way is stored in the corresponding brain memory section of the page memory 206 as shown in FIGS. 11(a), (b), and (C).
, G, B image data. For comparison, R, G, and B image data without antialiasing processing are shown in FIGS. 12(a), 12(b), and 12(C).

Through the above operations, brightness modulation processing for anti-aliasing processing that takes printer processes into consideration can be realized, and a stable and beautiful output image can always be obtained.

0 Configuration of Image Processing Apparatus The configuration of the image processing apparatus 400 will be explained with reference to FIG.

The image processing device 400 is a CC in the image reading device 300.
Black (BK), yellow (Y), and
It is converted into magenta (M) and cyan (C) recording signals. Further, the R, G, and B image data given from the PDL controller 200 described above are similarly converted into blank (BK), yellow (Y), magenta (M), and cyan (C) recording signals. Here, the mode in which image signals are input from the image reading device 300 is called a copying machine mode, and the mode in which RlG and B image data are input from the PDL controller 200 is called a graphics mode.

The image processing device 400 includes CCDs 7r, 7g, and 7b.
The color gradation data obtained by A/D converting the output signal of
A shading correction circuit 401 that performs correction for variations in sensitivity of internal terminal elements of 7r, 7g, and 7b, and color gradation data output from the shading correction circuit 401 or color gradation data output from the PDL controller 200 ( a multiplexer 40 that selectively outputs one of the R, G, and B image data according to the above-mentioned mode;
2, a γ correction circuit 403 that inputs the 8-bit data (color gradation data) output from the multiplexer 402, changes the gradation according to the characteristics of the photoreceptor, and outputs it as 6-bit data; and a γ correction circuit. (R) output from 403,
6-bit gradation data indicating the gradation of green (G) and blue (B) is converted into complementary colors cyan (C) and magenta (M).
, a complementary color generation circuit 405 that converts into yellow (Y) gradation data (6 bits), and a masking processing circuit 406 that performs predetermined masking processing on each Y, M, and C gradation data output from the complementary color generation circuit 405. , a UCR processing/black generation circuit 407 that inputs Y, M, and C gradation data after masking processing and executes UCR processing and black generation processing; and Y, which is output from the UCR processing/black generation circuit 407. M
, C1, and BK into 3-bit gradation data YLMLCL and BKI, and outputs them to the laser drive processing section 502 inside the multivalued color laser printer 500. 408, and a synchronization control circuit 409 for synchronizing each circuit of the image processing apparatus 400.

Although details will be omitted, the γ correction circuit 403 has a configuration in which the gradation can be arbitrarily changed using an operation button on the console 700.

Further, as an algorithm used in the gradation processing circuit 408, a multi-value dither method, a multi-value error diffusion method, etc. can be applied. For example, a dither matrix of the multi-value dither method is
x 3, the number of gradations of the multilevel color laser printer 500 is the product of the area gradation of 3 x 3 and the multilevel level of 3 bits (i.e., 8 levels), and 3X3X8 = 72 (gradations). Become.

Next, the processing of the masking processing circuit 406 and the UCR processing/black generation circuit 407 will be explained.

Generally, the arithmetic expression for masking processing of the masking processing circuit 406 is as follows: Y, M, C1: Masking processing unit data Yo, Mo
, Co: Data after masking processing Further, the arithmetic expression for UCR processing of the UCR processing/black generation circuit 407 is also generally expressed as follows.

Therefore, in this embodiment, new coefficients are obtained from these equations using the product of both coefficients.

In this embodiment, a new coefficient (alloo, etc.) that performs this masking process and UCR process simultaneously is calculated and obtained in advance, and further, using this new coefficient, the masking process circuit 4
06 scheduled input value Y.

Output values (such as yo': values that are the calculation results of the UCR processing/black generation circuit 407) corresponding to M, , C, (6 bits each) are obtained and stored in a predetermined memory in advance. Therefore,
In this embodiment, a masking processing circuit 406 and a UCR processing/black generation circuit 407 are constructed of one set of ROM.
Data at the address specified by inputs Y, M, and C of the masking processing circuit 406 is given as an output of the UCR processing/black generation circuit 407.

In addition, for fishing on a boat, the masking processing circuit 406 performs Y,
The M and C signals are corrected, and the UCR processing/black generation circuit 407 performs correction for dark color balance in overlapping toners of each color. After passing through the UCR processing/black generation circuit 407, black component data BK is generated by combining the input three color data of Y, M, and C, and the output data of each color component of Y, M, and C is It is corrected to a value obtained by subtracting the black component data BK.

In the above configuration, the γ correction circuit 403 executes processing based on the γ correction conversion graph shown in FIG. Assuming that processing is executed based on the generation conversion graph, and then the masking processing circuit 406 and the UCR processing/black generation circuit 407 execute processing based on the following equations, FIGS. 11(a), (b), For the R, G, B image data shown in (C), the γ correction circuit 403 and the complementary color generation circuit 40
5. Through the masking processing circuit 406 and the UCR processing/black generation circuit 407, the
), (d).

Furthermore, if the gradation processing circuit 408 uses a Bayer type 3×3 multivalued dither matrix shown in FIG. 17, the Y in FIGS. ,M,C,
The BK data are shown in Figures 18 (a), (b), and (C), respectively.
), converted into the data shown in (d).

For comparison, when data without anti-aliasing processing (data in FIGS. 12(a), (b), and (C)) is processed by the image processing device 400, the 19th
The data is converted as shown in Figures (a), (b), (C), and (d).

■Configuration of multi-value color laser printer, configuration and operation of developing section of multi-value color laser printer First, the schematic structure of multi-value color laser printer 500 will be explained with reference to the control block diagram shown in FIG. 20. do.

A photoreceptor development processing unit 501 uniformly charges the surface of a photoreceptor drum (described later), exposes the charged surface to a laser beam to form a latent image, develops the latent image with toner, and transfers it to recording paper. Details will be given later, but BK Deday's development and
A black developing/transfer section 501bk that performs transfer, a cyan developing/transfer section 501c that develops and transfers C data,
A magenta developing/transfer section 50 that develops/transfers M data.
1m, and a yellow developing/transfer section 501y that develops and transfers Y data.

The laser drive processing unit 502 includes the image processing device 4 described above.
The laser beam is output by inputting the 3-bit data of Y, M, C, and BK output from 00 (in this case, image density data). Input buffer memory 503y, 503m
, 503c, and a laser diode 504y that outputs laser beams corresponding to Y, M, C, and BK, respectively.
504m, 504c, 504bk and laser diodes 504y, 504m, 504c.

Drivers 505V each drive 504bk.

It consists of 505m, 505c, and 505bk.

In addition, the black developing/transfer section 5 of the photoreceptor development processing section 501
01bk, the laser diode 504bk of the laser drive processing section 502, and the driver 505bk are called a black recording unit BKU (see FIG. 21(a)). Similarly, the combination of cyan developing/transfer section 501c, laser diode 504c, driver 505c, and buffer memory 5D3c is combined with cyan recording unit CU (see FIG. 21(a)), magenta developing/transfer section 501m, laser diode 504m, The combination of the driver 505m and the buffer memory 503m is used as a magenta recording unit) MU (see FIG. 21(a)).
, yellow developing/transfer section 501y, laser diode 504y, driver 505M, and buffer memory 503y are combined into a yellow recording unit) YU.
(See FIG. 21(a)). As shown in the figure, each of these recording units is connected to a conveyor belt 506 that conveys the recording paper.
Black recording unit B from the recording paper conveyance direction
KU, cyan recording unit CU, magenta recording unit
-MU, yellow recording unit YU are arranged in this order.

Due to this arrangement of each recording unit, the laser diode 5 for black exposure starts exposure first.
04bk, and the laser diode 504y for yellow exposure starts exposure last. Therefore,
There is a time difference in the order of exposure start between each laser diode,
Data recorded during the time difference (output of the image processing device 400)
In order to hold the data, the laser drive processing unit 502 includes the three sets of buffer memories 503y, 503m, and 503C described above.
is provided.

Next, the configuration of the multivalued color laser printer 500 will be specifically explained with reference to FIG. 21(a).

The multilevel color laser printer 500 includes a conveyance heald 506 that conveys recording paper, and recording units YU, MU, and YU arranged around the conveyance belt 506 as described above.
, CU, , BKU and a paper feed cassette 5 containing recording paper.
07a, 507b and paper feed cassette) 507a, 507b
Paper feed rollers 508a and 50 that feed the recording paper from
8b, a registration roller 509 that aligns the recording paper sent out from the paper feed cassettes 507a and 507b, and a conveyor belt 506 to move the recording units BKU and CU.
, MU, and YU and fixes the transferred image on the recording paper, and a paper discharge roller 511 that discharges the recording paper to a predetermined discharge section (not shown). Here, each recording unit YU, MU, CU, BK
U represents photosensitive drums 512y, 512rn, 512c,
512bk, and photoreceptor drums 512y and 512, respectively.
Charger 51 that uniformly charges 512C1512bk
3y, 513m, 513c, 513bk, and polygon mirrors 514y, 514 for guiding the laser beam to the photosensitive drums 512y, 512m, 512C1512bk.
m, 514c.

514bk and motor 515y, 515m, 515C1
515bk, photosensitive drums 512y, 512m, 51
A toner developing device 51 that develops the electrostatic latent image formed on 2C1512bk using toner of a corresponding color.
6y, 516m, 516c, 516bk, and transfer chargers 517y and 517 that transfer the developed toner image to recording paper.
m, 517c, 517t)k, and cleaning devices 518y, 518 for removing toner remaining on the photoreceptor drums 512y, 512m, 512c, 512bk after transfer.
m, 518C1518bk. In addition, 51
9y, 519m, 519c, and 519bk are photosensitive drums 512y, 512m, 512c, and 512bk, respectively.
COD for reading the predetermined pattern provided on the
A line sensor is shown, and although its details are omitted, it detects the process status of the multivalued color laser printer 500.

In the above configuration, the operations of the yellow recording unit YU will be explained using exposure, development, and transfer as examples.

FIGS. 22(a) and 22(b) show the configuration of the exposure system of the yellow recording unit YU. In the figure, a laser beam emitted from a laser diode 504y is reflected by a polygon mirror 514y, passes through a -θ lens 520y, is further reflected by mirrors 521y and 522y, passes through a dustproof glass 523y, and hits a photosensitive drum 512y. At this time, the laser beam hits the polygon mirror 51.
4y is driven to rotate at a constant speed by the motor 515y, so it moves in the direction along the axis of the photosensitive drum 512y (main scanning direction). Furthermore, in this embodiment, a photosensor 524y is provided to detect the base point for tracking the scanning position of the main scan, so that the laser beam at the non-exposed position is detected. Since the laser diode 504y is activated to emit light based on the recorded data (3-bit data from the image processing device 400), multivalue exposure corresponding to the recorded data is applied to the photoreceptor drum 514y.
performed on the surface of The surface of the photoreceptor tram 514y is uniformly charged in advance by the charger 513y as described above, and an electrostatic latent image corresponding to the original image is formed by the exposure. The electrostatic latent image is developed by a yellow developing device 516y to become a yellow toner image. This toner image is
As shown in FIG. 21(a), paper feed roller 508a (or
508b), and is transferred by registration rollers 509 onto a recording sheet conveyed by a conveyor belt 506 in synchronization with the formation of a toner image in a black recording unit (BKU).

Other recording units BKU, CU, and MU have similar configurations and perform similar operations, but black recording unit BK
U includes a black toner developing device 516b+k to form and transfer a black toner image, a cyan recording unit CU includes a cyan toner developing device 516c to form and transfer a cyan toner image, and a magenta recording unit MU includes a cyan toner developing device 516c to form and transfer a cyan toner image. A magenta toner developing device 516m is provided to form and transfer a magenta toner image.

Next, there are two types of means for detecting the remaining amount of toner in the hopper.

1. A method of converting the rotational torque of the agitator in the hopper into an electric signal and detecting it. 2. A method of monitoring the ON/OFF signal of the ultrasonic vibrating element (in this method, (Feedback processing can be performed by detecting the number of ON/OFF cycles, etc.) Here, for example, 2. Ultrasonic vibration element 5
When using 90y, 590m, 590c, 590-bk (see Figure 21 (a)), the ultrasonic vibration element is turned off.
The relationship between time and the remaining amount of toner is as shown in FIG. 21(b). That is, the OFF time becomes 0 at the end of toner.

This relationship is unique to the printer (electrophotographic process), and the OF of the ultrasonic vibration element when the toner is full.
The F time was divided equally into n stages from 0. ff time Tof
Density value ID when the γ characteristic corresponding to f, H (however, an integer of 0≦j≦n) is evenly divided into tone value bones (m stages) of the printer, (however, an integer of 0≦j≦m) ) is determined in advance through experiments, etc.

Then, as shown in Fig. 22 (smell flow chart),
When the γ characteristic is linear, the corrected approximate area ratio hkJ is calculated using the density value IDR1 equally divided into m stages (an integer of 0≦i≦m) as hk, -(IDR, -ID□)/
ID.

is calculated and stored so that the CPU 202 in the PDL controller 200 can refer to it (step 52201).

On the other hand, the printer 500 checks the T oH when the graphic output operation is completed or every certain number of sheets, and determines the nearest number of stages j.
is transferred to the PDL controller 200 via the system control unit 600 (step 52202).

■Multi-value drive of driver Drivers 505y, 505m, 505c.

505bk is Y sent from the image processing device 400.
, M, CXBK, the corresponding laser diode 504F.

It performs control for multi-value driving of 504m, 504c, and 504bk, and power modulation, pulse width modulation, etc. are generally used as the driving method.

Hereinafter, multi-level drive using power modulation applied in this embodiment will be explained in detail. In addition, drivers 505y, 505m, 5
05c, 505bk, and laser diode 504
y, 504m, 504c.

Since the components 504bk each have the same configuration, the driver 505y and the laser diode 504y will be described here as an example.

As shown in FIG. 22(C), the driver 505y turns the laser diode 504y on and off based on a predetermined LD drive clock.
n10ff circuit 550 and 3-pit image density data (
Here, the D/A converts Y data) into an analog signal.
From a converter 551 and a constant current circuit 552 that inputs an analog signal based on the image density value from the D/A converter 551 and supplies a current (LD drive current) Id for driving the laser diode 504y to the laser diode on10ff circuit 550. configured.

In the above configuration, the laser diode on/o
f f circuit 550 causes laser diode 504y
emits light, and a laser beam is emitted to the photoreceptor drum 512y.

Here, the LD drive clotter is defined as "on at 1" and off at 0, and as shown in FIG. 22(d), the laser diode on10rr circuit 550 turns on and off the laser diode 504y accordingly. Furthermore, since the LD drive current Id and the laser beam power are in a proportional relationship, by generating the LD drive current Id based on the image density data value, the laser beam power output corresponding to the image density data value can be obtained. become. For example, as shown in FIG. 22(d), when the image density data value is "4" (data N-1 in the figure), the corresponding LD drive current 1d is supplied by the constant current circuit 552, The laser beam power of the laser diode 504y is level 4. Also, the image density data value is "7" (
In the case of data N) in the figure, the corresponding LD drive current 1d is supplied by the constant current circuit 552, and the laser beam power of the laser diode 504y becomes level 7.

Next, the specific circuit configurations of the laser diode ON10ff circuit 550, the D/A converter 551, and the constant current circuit 552 will be described with reference to FIG. 22(e).

The laser diode on10ff circuit 550 is TTL
Inverters 553 and 554, differential switching circuits 555 and 556 that perform onloff toggle operation, and V
When GI>VO2, the differential switching circuit 555 is
n, the differential switching circuit 556 is ofr, VGl<
When VO2, the differential switching circuit 555 is off,
Resistors R2 and R form a voltage dividing circuit that generates VC2 that satisfies the conditions for the differential switching circuit 556 to be turned on.
It consists of , and.

Therefore, when the LD drive clock is "1", the output of the inverter 554 generates VGI, and the condition (VGI
>VC2), the differential switching circuit 555 is turned on, the differential switching circuit 556 is turned off, and the laser diode 504y is turned on. Also, conversely, LD
When the drive clock is "'0", the inverter 55
Since there is no output of 4, the condition (VC, 1 < VC2) is satisfied, the differential switching circuit 555 turns on ofr, the differential switching circuit 556 turns on, and the laser diode 504y turns off.

The D/A converter 551 includes a latch 557 that launches the input image density data while the LD drive clock is "°1", and a latch 557 that launches the input image density data while the LD drive clock is "°1", and a latch 557 that launches the input image density data while the LD drive clock is "1"
Generator 558, image density data and maximum output value V r
It is composed of a 3-bit D/A converter 559 that outputs analog data Vd based on af. Note that the relationship between Vd, image density data, and maximum output value ■r□ is expressed by the following equation.

The constant current circuit 552 includes the laser diode 504 in the laser diode ON10ff circuit 550 as described above.
y current, and the transistor 560
and resistors R4 and R6. The output Vd from D/A converter 551 is applied to the gate of transistor 560 to determine the voltage applied to resistor R4.

In other words, the current flowing through the resistor R4 is the current flowing through the transistor 5.
60, the current Id flowing through the laser diode 504y is controlled by Vd.

22) is the output of the latch 557 mentioned above, VGl
, Vd, and Td. Here, Vd is image density data (3 focus data:
Based on 8 gradation data from 0 to 7), VrQf×0/7
Values are taken in 8 stages from ~7/7, and Id is 1. to 7/7 based on this VdO value. - Shows 8 levels of Iヮ. The laser diode 504y has 8 levels of this Id (20
- Level O, I, = Levelt..., ■7 - Level 7)
Accordingly, a latent image as shown in FIG. 23 is formed on the photosensitive drum 512y.

Further, in this embodiment, multi-value driving using power modulation is applied, but it goes without saying that similar effects can be obtained by using multi-value driving using pulse width modulation.

For reference, FIG. 24 shows changes in the latent image form depending on the level of modulation during the pulse.

〔Effect of the invention〕

As explained above, according to the graphic processing apparatus according to the present invention, an anti-aliasing processing means for smoothly expressing jagged edges (aliasing) of an output image, and an image subjected to anti-aliasing processing by the anti-aliasing processing means A graphic output device comprising an image output means for outputting data using a series of electrophotographic processes, a detection means for detecting a residual level of developer used in development processing in the electrophotography process; Since a correction means is provided for correcting the luminance value or density modulation processing result of the anti-aliasing processing according to the residual level detected by Modulation processing can be realized at low cost and with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of the image forming system of this embodiment, FIGS. 2(a) and (b) are explanatory diagrams showing antialiasing processing using the uniform averaging method, and FIGS. 3(a) and ( b
) is an explanatory diagram showing anti-aliasing processing using the weighting averaging method, Figure 4 (a), (b), (C), (d)
is an explanatory diagram showing an example of a filter used in the weighted averaging method, Fig. 5 is an explanatory diagram showing a convolution method with 3 x 3 pixel reference, and Figs. 6 (a), (b), (C), (d), (
e) and ge) are explanatory diagrams showing the anti-aliasing process to obtain the approximate area ratio of edge pixels, Fig. 7 is an explanatory diagram showing the configuration of the PDL controller, and Fig. 8(a) shows the operation of the PDL controller. Flowchart, Figure 8(b)
8(C) is an explanatory diagram showing path filling processing, FIG. 8(C) is a flowchart showing antialiasing processing according to the present invention, FIGS. Figure (C) is an explanatory diagram showing an example of 3 x 3 pixels, Figure 9 (d) is an explanatory diagram showing an example of a filter using the uniform averaging method, and Figure 9 (e) is an explanatory diagram showing an example of a filter using the uniform averaging method. An explanatory diagram showing the result when each pixel shown in FIG. 9(C) is applied with the shown filter, FIG. 10 is an explanatory diagram showing the approximate area ratio after performing anti-aliasing processing, and FIG. 11(a) ,
(b) and (C) are explanatory diagrams showing R, G, and B image data stored in the plain memory section of the page memory.
Figures 2 (a), (b), and (C) are explanatory diagrams showing R, G, and B image data stored in the plain memory section of the page memory when anti-aliasing processing is not performed, and Figure 13 is an image Explanatory diagram showing the configuration of the processing device, No. 14
The figure is an explanatory diagram showing the conversion graph for γ correction of the T correction circuit, Figures 15 (a), (b), and (C) are explanatory diagrams showing the conversion graph for complementary color generation used in the complementary color generation circuit, and Figure 16 (a)
, (b), (C), (d) are shown in Fig. 11 (a), (b),
Explanatory diagram showing the state in which the R, G, B image data shown in (C) is output from the UCR processing/black generation circuit, No. 17
The figure is an explanatory diagram showing a Bayer-type 3×3 multivalued dither matrix, and FIGS. 18(a), (b), (C), and (d) are shown in FIGS. C), Y, M, C of (d),
An explanatory diagram showing the state in which BK data has been converted by the gradation processing circuit. FIG. 20 is a control block diagram showing a multivalued color laser printer, and FIG. 21(a) is an explanatory diagram showing the configuration of the multivalued color laser printer. , FIG. 21(b) is a graph showing the relationship between the OFF time of the ultrasonic element and the remaining amount of toner. Figure 22(a),
(b) is an explanatory diagram showing the configuration of the exposure system of the yellow recording unit, Fig. 22 (C) is an explanatory diagram showing multivalue drive by power modulation, and Figs. 22 (d) and (f) are the operation of the laser diode. A timing chart explaining FIG. 22 (e
) is a circuit diagram showing the configuration of the laser diode ON10ff circuit, etc., FIG. 22 is a flowchart showing the operation of the printer, FIG. 23 is an explanatory diagram showing the state of the latent image depending on the power modulation level, and FIG. 24 is the pulse An explanatory diagram showing the state of a latent image depending on the level of width modulation. Figure 25 is a graph showing the image density versus surface potential of the photoreceptor when using a single-component magnetic toner. Figure 26 is a graph showing the image density versus the surface potential of the photoreceptor when using a single-component non-magnetic toner. It is a graph showing the image density versus the surface potential of the photoreceptor when used.Explanation of symbols 0...Host computer 0--PDL controller 1-Receiving device 202-CPU 3-Internal system bus 4-RAM 205--ROM 6-page memory 207-transmitting device 8, -1/O device 300-image reading device 0...
- Image processing device - Multivalued color laser printer No. (a) kid=255 (b) x7 kid= 255x28/49 (a) cone fitter No. 4 (a) cyHndrtcal filter diagram (b) Diagram (b) cone filter (C) y' Hue (e) Figure (a) Figure (C) tttr Suβ Figure (b) Figure 9 (C) Figure (e) ×n-1 n Xn+1 Xn+2, Xn+3, Xn+4. (o) BK data (c) M data 16th ward (b) C data (d) Y data. Dark 14゜"710 工○ ol. O40-0 010142163, 10tO Oj42163163 甜28163163, i63゜6316316B 'l'l. l010 ol. 0121.135!28: i day °I ○ ol. 3 Bayer type dot level dot level 17 diagram Multi-level dither matrix dot level dot level O-noher Figure 18 (b) C data (d) Y data Figure 19 (b) C data (cl) Y data Figure 20 Recording paper conveyance direction (b) off Toner amount (a) (b) (cl) Fig. 23

Claims (4)

[Claims] (1) An anti-aliasing processing means that smoothly expresses jaggedness (aliasing) at the edges of an output image; and an image that outputs image data subjected to anti-aliasing processing by the anti-aliasing processing means using a series of electrophotographic processes. A graphic output device comprising: a detection means for detecting a residual level of a developer used in development processing in the electrophotographic process; and an anti-aliasing process according to the residual level detected by the detection means. 1. A graphic output device comprising: a correction means for correcting a luminance value or a result of density modulation processing. (2) In claim 1, the developer is a one-component developer, and a correction means is provided for correcting the brightness value or density modulation processing result of the anti-aliasing processing according to the residual level of the developer in the hopper. A graphic output device characterized by: (3) The graphic output device according to claim 1, wherein the detection means converts the rotational torque of an agitator in the hopper into an electric signal to detect the residual level of developer. (4) The graphic output device according to claim 1, wherein the detection means detects the residual level of the developer by monitoring an ON/OFF signal of an ultrasonic vibration element.