JPH0477176A - Image forming device - Google Patents

Abstract

PURPOSE:To allow the operator to obtain a desired density directly by providing an input means to set a copy picture density and a density control means sharing the entire copy picture density able to set a copy picture on one transfer paper according to the setting of the input means to the image forming device. CONSTITUTION:When R, G, B data from a scanner are used as reflectance data, a gamma correction section 101 to set copy picture density matches a gray balance to form a density data. Then a black density calculation section 102 calculates a black density and a background elimination section 103 subtracts the black density from the R, G, B density obtained by the gamma correction and a masking section 104 generates a complementary color from R',G',B' to obtain C, M, Y and Bk data. A gamma table 105 corrects the data into a dither picture input level for a dither processing section 106. Plural gamma curves for each color are prepared and selected by a control box 107 as the density control means. Various density curves are obtained by indexing the table.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to image forming apparatuses such as copying machines, printers, facsimiles, etc., and particularly relates to an image forming apparatus characterized by copy image density control.

[Conventional technology]

Generally, in an image forming apparatus, the density of an image is changed by automatically or manually switching a developing bias value and exposure amount.

If the obtained copy image density (hereinafter simply referred to as density) is not the desired density, switch from manual to automatic, or from automatic to manual, or even from manual to manual in another density range, and then try copying the image again. I was getting it.

Note that "manual" here refers to operating analog keys provided on the operation panel or notch keys corresponding to each density.

[Problem to be solved by the invention]

However, there is a problem in that it is not always possible to obtain the desired density in one operation, and it is often the case that the desired density cannot be achieved until copying is repeated two or three times.

The present invention has been made based on this background, and an object of the present invention is to provide an image forming apparatus capable of producing an image corresponding to each notch on a single copy as a density test sample.

(Means for solving Rla) The above purpose is to provide an input means for setting copy image density;
This is achieved by providing a density control means that allocates all settable copy image densities to the copy image on one sheet of transfer paper according to the settings of the input means.

Further, the above purpose is to provide a copy image density array in the above,
This can also be achieved by matching the array of input means for each copy image density.

[Effect]

The density control means is operated to copy an image having a density for each input means (each notch key) onto a sheet of transfer paper.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First, FIG. 2 shows a block diagram of a digital copying machine as a general image forming apparatus.

In this device, data of a document is read by an image scanner 201, and an image processing unit 202 performs gamma correction, dither processing, etc. (masking, etc. in the case of color), and sends the processed data to a printer 203. . Gamma correction serves to adjust the gradation of data read from the scanner 201 to match the ink characteristics (density and reflectance characteristics) of the printer 203, but in the present invention, there are multiple gamma curves and one can be selected. The concentration changes are realized by

Next, the block diagram of FIG. 1 shows a specific example of changing the density by gamma correction in the image processing unit 202. Note that this embodiment is for a color copy.

When the R, G, and B inputs from the scanner 201 are used as reflectance data, the gamma correction unit 10 sets the copy image density.
In step 1, the Daleiharance is combined and used as concentration data. Next, the black density calculation unit 102 calculates the black density,
R, G, and B obtained earlier by gamma correction in the undercolor removal unit 103
The black density is subtracted from the density of R', G', and B' to generate complementary colors in the masking unit 104, and C, M, Y, and Bk are generated.
Get data. The gamma table 105 is the dither processing unit 1
This is to correct the input level for dither processing of 06,
Conventionally, there was one gamma curve for each color as shown in Figure 3 (al).However, in the present invention, several gamma curves for each color are prepared as shown in Figure 3 (b), and a control box is used as a density control means. 107 so that it can be selected.

Here are some possible control boxes 107.

(Set the 11 counter IC and count the lines,
(2) A method in which the gamma curve is selected by hardware based on the output value; (2) A method in which the CPU is set, increments are applied using a line signal, the line is detected by a counter inside the CPU, and the gamma curve is selected by software; This embodiment The timing chart in FIG. 4 shows the relationship between the clock and data. 1 copy clock signal is 5TART, 1 line clock signal is LSYNC, 1
The clock signal for each pixel is CLK. Examples of circuits of the control box (11, (2)) using this timing are shown in FIGS. 5(a) and 6.

The control box shown in FIG.
1 and is composed of a counter IC 501.

The control box shown in FIG. 6 corresponds to (2) and is composed of a CPU 502. Figure 5 (bl is a diagram showing the gamma curve. Various density curves can be obtained by assigning the table. Also, CP
When using U502, O” as shown in Figure 6 (bl)
It can be numbered as n, n+Im and selected by software processing.

Counter Ic501 as control box 107
When using this, the internal configuration becomes simple, and it is convenient when it is desired to create a gradation-like density change. Also CP
Providing U502 increases the cost, but since it is controlled by software, it is possible to realize a device that can dynamically change or be specified by the user.

5 and 6 are block diagrams for changing the density in the sub-scanning direction, while FIGS. 7 and 8 are block diagrams for changing the density in the main scanning direction.

By the way, the present invention outputs images with a plurality of densities (set by a notch key described later) on one sheet of transfer paper, and the methods for changing the densities are: 1. Changing the densities by selecting a gamma curve; 2. For example, changing the developing bias at the appropriate timing.

Here, we will discuss the area where the density can be changed.

The user can also specify any part (area) of the image and specify the density of that part (the method of specifying the area is disclosed in Japanese Patent Application No. 153611/1983, so the explanation will be omitted). , - If you find it troublesome to specify the area and density, set the area and density from the beginning.
To easily output an image in which all notches are assigned (all densities that can be set are assigned).

Next, a method of changing density using a developing bias will be explained.

FIG. 9 is a block diagram of the main parts of the printer section, and a developing bias high voltage power supply 901 has a trigger signal line and four signal lines 0 and 1 from the main control section 902 to which the output voltage is changed.
．． 2 and 3 are respectively sent out and connected. The development bias high voltage power supply 901 is set to an output voltage as shown in FIG. 10 by the combination of rHJ and rLJ by each of the four signal lines 0.12.3.

Further, a timing chart at that time is shown in FIG.

Turn on the developing bias one second after turning on the print key. After that, the voltage is lowered every t8 seconds, and the notches 1 to n
Reproduce the image up to. In the figure, the voltage is lowered over time, but a similar image can be obtained even if the voltage is raised from the bottom.

FIG. 12 is an explanatory diagram of an example of copying by the process according to the present invention, in which (a) is an original, (mountain) is a copy when the image is divided horizontally, and (C) is a copy when the image is divided vertically. Indicates a copy of However, when controlling the density with the developing bias, it is limited to the horizontal direction of (bl).

When it is desired to select the density of a part of an image, the image can be enlarged and output using the variable magnification circuit in the image processing section 202 shown in FIG.

FIG. 13 is a plan view of the operation panel 108 shown in FIG.
A plurality of notch keys (input means) 109 are provided.

〔Effect of the invention〕

As explained above, according to the invention as claimed in claims 1 and 2, an image having a density corresponding to each input means is formed on one sheet of transfer paper by operating the density control means. You can directly select the desired density by looking at it.

[Brief Description of the Drawings] Fig. 1 is a block diagram of an image processing section according to an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of a general digital copying machine, Fig. 3(a), (b) is a comparative characteristic diagram of gamma curves, FIG. 4 is a timing chart showing the relationship between clock and data, and FIG. 5 (a) is a block diagram showing an example of a control box for changing the density in the sub-scanning direction. ('b) is a characteristic diagram showing the specified gamma curve, FIG. 6 is a control block 7 for changing the density in the sub-scanning direction, (7) is a block diagram showing another example, and FIGS. Figure 8 is a block diagram showing each side of the control box for changing the density in the main scanning direction, Figure 9 is a block diagram of the main parts of the printer section, and Figure 10 is an explanatory diagram showing the relationship between signal lines and developing bias voltage. , FIG. 11 is a timing chart regarding the developing bias, FIG. 12 is an explanatory diagram showing the correspondence between originals and copies, and FIG. 13 is a plan view of the operation panel. 107... Control box, 109... Notch key Figure (a) (b) All L Hano L Figure Figure Figure Figure Figure Shi - Boo! ! Figure O Figure O Figure An O

Claims (2)

[Claims] (1) An input means for setting the copy image density, and a density control means for distributing all copy image densities that can be set to the copy image on one sheet of transfer paper according to the settings of the input means. Image forming device. (2) In claim 1, a copy image density array;
An image forming apparatus characterized in that the arrangement of input means corresponds to each copy image density.