JP2875527B2 - Color image forming equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image forming apparatus, and more particularly, to a color image forming apparatus suitable for judging which condition is optimal for one copy. is there. (Prior Art) In a color copying apparatus, several test copies are often required to adjust the color balance of a color copy to the user's preference. One of the reasons is the fluctuation of the apparatus itself, such as the stability of the apparatus, especially the stability of the potential of the photoconductor, the concentration of the developer, and the amount of charge of the developer. At present, it is difficult to obtain a satisfactory color balance copy with one copy due to the problem of preference. (Purpose) The present invention has been made in view of the above-described disadvantages of the related art, and has as its object to provide a color image forming apparatus having a color test copy mode capable of immediately obtaining an optimum value of color balance. Is to provide. (Structure) In order to achieve the above object, the present invention provides a color image forming apparatus that forms a color image by combining yellow, magenta, and cyan developers, and forms different images on a plurality of areas in one screen. Control means for executing a color test mode for determining which condition is optimal in one transfer sheet; and sequentially setting image forming process conditions for yellow, magenta, and cyan for each of the plurality of areas. Yellow, magenta,
Memory means for storing image forming process conditions for image formation for each of cyan, and when the control means executes the color test mode, the one screen is set based on the image forming process conditions of the memory means. The image forming process conditions of yellow, magenta, and cyan are sequentially changed for each of the plurality of regions, and the respective colors are combined to form an image.
The configuration is such that a plurality of test color images in which the color balance is sequentially changed are formed in the screen. Hereinafter, a specific description will be given based on an embodiment of the present invention. First, the overall configuration of a color copying apparatus to which the present invention is applied will be described with reference to the schematic diagram of FIG. In particular, the figure is a schematic diagram showing the periphery of the photosensitive drum of the digital color copying machine,
1 is a polygon me, 2 is an fθ lens, 3 is a mirror, 4 is a laser beam, 5 is a photosensitive drum, 6 is a charger, 7 is a yellow developing device, 8 is a magenta developing device, 9 is a cyan developing device, 10 is a cyan developing device. Black developing unit, 11 is a photo sensor, 12 is a pre-transfer lamp, 13 is a pulse counter, 14 is a transfer drum, 15 is a transfer charger, 16 is a static charger before cleaning, 17 is a separation charger, 18 is a cleaning device, and 19 is a yellow supply signal. Line, 20 is a magenta supply signal line, 21 is a cyan supply signal line, 22 is a black supply signal line, 23 is a yellow developing bias signal, 24 is a magenta developing bias signal, 25 is a cyan developing bias signal, and 26 is a black developing bias signal. , 27 is a photosensitive drum rotation pulse signal line,
28 is a photo sensor output line. As shown in the figure, this digital color copying apparatus has a writing laser optical system (polygon mirror 1, fθ lens 2, mirror 3, laser beam 4, etc.) and developing devices for four colors, ie, yellow, magenta, cyan and black. 7 to 10, a photosensitive drum 5 and a transfer drum 14. In the figure, the portions indicated by blocks are a development control unit 42, an operation panel 43, a main body control unit (CPU) 44, a mode memory 45, a scanner unit and a control circuit 46, an image processing unit and a control circuit 47. And 48 indicate a blotter section and a control circuit. FIG. 2 is a block diagram further explaining the image processing section 47 of the color copying apparatus. In the figure, 46 is a scanner section, 44 is a main body control section, 32 is a synchronous control circuit, 33 is a printer section, 34 is a laser, 35 is a laser unit, 36 is a shading correction circuit, 37 is a gamma correction circuit, and 38 is a masking process. The circuit, 39 is a UCR processing circuit, 40 is a density pattern circuit, and 41 is a multi-value processing circuit. In the above configuration, the scanning unit 30
In the image signal read by the CCD light receiving unit, the optical illumination unevenness is corrected by the shading correction circuit 36 for each of yellow (Y), magenta (M), and cyan (C). The gradation of each color signal is corrected by the gamma correction circuit 37. The masking correction circuit 38 calculates the optimum amounts of yellow Y, magenta M, and cyan C at the time of printing, and calculates UC
The R processing circuit 39 calculates an appropriate black Bk amount for producing black from yellow Y, magenta M, and cyan C.
Next, the density pattern processing circuit 40 outputs a pattern distribution corresponding to each of the 64 gradations, and outputs the multivalued processing circuit.
At 41, pulse width modulation is performed according to the 1 to 4 values in the pattern. The synchronization control circuit 32 controls the processing circuits in synchronization. FIG. 3 is a perspective view schematically showing the overall appearance of the color copying apparatus of the above embodiment, in which 43 is an operation panel, 44 is a main body control unit (CPU), 46 is a scanner unit, and 47 is image processing. Part, 4
8 is a blotter part, 49 is a pressure plate, and 50 is a platen glass. Next, a test color copy which is the gist of the present invention will be described. FIG. 4 shows one transfer sheet divided into nine areas. Each area in this one sheet of transfer paper is controlled so as to produce different colors by changing the conditions of the image forming parameters. The main image forming patterns include the charge amount (on the photosensitive drum 5), the amount of laser beam, the developing bias, the toner concentration, the transfer conditions, and the like. Of these, relatively easily within one sheet of transfer paper The means based on the developing bias is suitable because it can be controlled and the effect of the color change is large. Hereinafter, a case using the developing bias will be described as an example. An example will be described for negative-positive development with negative charging. Negative-positive development is a method in which a portion having a high absolute value of the charged potential becomes a background of development and a portion having a low absolute value is an image portion, that is, a portion where toner adheres. For example, the charging potential of the photosensitive drum 5 in FIG.
00V, and the normal developing bias value for this initial potential is -500 to -550V in the case of negative-positive development. −500
Using V as a reference value, a fluctuation width of one step is set to 60V.
This 60V width is the same as the bias value width when changing the normal copy image density value, and is a value where the change in density appears appropriately. If the width of the bias value is large, the change in hue becomes large, and it is difficult to find the optimum condition. Conversely, if the bias value width is too small, the change is small and the effect is lost. The potential at the time of development is changed by selectively changing each bias value during the development of yellow, magenta, cyan, and black. As a result, the amount of toner adhered to each color changes, and as a result, images having different color balances can be obtained. FIG. 5a is a table showing the assignment of the developing bias values. Each variation in each area is changed by -60 V for each of cyan (C), magenta (M), and yellow (Y) [reference value -500 + (-60) = -560 V]. Magenta and then yellow.
,, Change C, M, Y by + 60V (−500 + 60 = −440
V) results in a leaning toward the complementary red (R) by reducing cyan, a green (G) by reducing the magenta color, and a complementary blue (B) by reducing the yellow color. ,, Control the brightness, that is, the so-called density, without changing the hue, are the thin, normal reference mode, and the dark mode. As described above, nine image modes, namely, C, M, Y, R, G,
Images tilted in the B, bright, normal, and dark directions are obtained.
As described above, images slightly different in six types of hues and three types of brightness are obtained, and the direction of color correction is determined. As shown in the time chart of FIG. 2b, which shows the timing of the bias control, for example, the process speed (moving speed of the photosensitive drum 5) is set when the transfer paper is A4 size vertical feed. If 120 mm / sec, A4 length ≒ 300 cm, 30
0 / (9 × 120) ≒ 0.28 sec, and the bias setting time of each area is 0.28 sec. Similarly, 420 / (9 × 120) ≒ 0.39 sec for other sizes, such as A3 portrait. These are the transfer paper size selection buttons 51 on the operation panel 43 (Fig. 6b).
Is determined by FIG. 6a is a flowchart showing the operation control flow of the above embodiment, and FIG. 6b is a schematic diagram showing a part of the operation panel. In FIG. 6b, reference numeral 51 denotes a transfer paper size selection button;
Is a segment display, 53 is a memory key, 54 is a clear key,
55 is a numeric keypad, 56 is a test mode copy button, and 57 is a copy button. This will be described with reference to the flowchart of FIG. 6a. First, after setting the original, the user selects a paper size by using the transfer paper size selection button 51. Next, when the user selects the test mode copy button 56, the image forming process starts.
When 55 is turned on, the bias setting value from the bias table in the mode memory is
Sent to In addition, as for the timing of the bias control at the time of image formation, a control signal to the plotter 48 is transmitted by an instruction of the main body control unit 44 according to an input signal of the transfer paper size selection button 51. After the test copy is obtained, the user determines which region from the image front end (from the extraction direction) is the optimum condition. Then enter the number of the key and press the memory key
Set at 53. After the test copy image formation, the processing circuit is in a state of waiting for a condition input (what number), and waits until the memory key 53 is turned on. After this memory key 53 is turned on,
The condition is set to the new reference value. This means the second position in FIG. 4b, that is, 0. Therefore,
At the beginning, C = 0, M = 0, Y = 0 are the reference values, each of which is -500V (Fig. 5a)
However, when the test copy is selected, the reference values of C = 0, M = 0, Y = 0 are C = −440V, M = −50.
0V, Y = -500V is set. Therefore, when the copy button 57 is turned on, the bias value of this set is set. This set value is input to the non-volatile memory, and the power is turned off.
It is stored even after turning on. However, by the continuous operation of the clear key 54 and the memory key 53, the initial reference values are reset to -500V. In the above embodiment, the bias setting width was set to 60 V, but 120 V
Alternatively, when the voltage is changed to 180 V, the color changes greatly, and a pseudo-color copy can be obtained from a black-and-white document. For example, it is possible to obtain a color image having a stripe-like color different from a black-and-white original such as Meyu or Latishi. (Effects) As described above, control means for executing a color test mode in which different images are formed on a plurality of regions in one screen and which condition is optimal in one transfer sheet. The image forming process for yellow, magenta, and cyan images is formed such that the image forming process conditions for yellow, magenta, and cyan are sequentially changed for each of the plurality of regions and the respective colors are combined to form an image. A memory means for storing process conditions, wherein when the color test mode is executed by the control means, yellow is set for each of a plurality of areas in the one screen based on the image forming process conditions of the memory means. , Magenta, and cyan image forming process conditions are sequentially changed, and the respective colors are combined to form an image, thereby forming a plurality of test color images having sequentially changed color balances within one screen. Therefore, an image having a different color balance can be obtained for each of a plurality of regions, so that a delicate color balance can be compared at a glance, and an optimum value of the color balance can be immediately obtained according to a user's preference or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the overall configuration of a digital color copying apparatus to which the present invention is applied, FIG. 2 is a block diagram illustrating an image processing section, and FIG. A schematic perspective view,
FIG. 4a is an explanatory view for explaining one sheet of transfer paper divided into nine areas, FIG. 4b is a view showing FIG. 4a encoded for each color, and FIG. 5a is a table showing development bias values. Fig. 5b is a time chart showing the timing of the developing bias, Fig. 6a is a flow chart for explaining the operation control flow of the apparatus according to the present invention, and Fig. 6b is a schematic diagram of an operation panel. 7: yellow developing device, 8: magenta developing device, 9: cyan developing device, 43: operation panel.

Claims (1)

(57) [Claims] In a color image forming apparatus that forms a color image by synthesizing yellow, magenta, and cyan developers, different images are formed on a plurality of areas in one screen.
A control unit for executing a color test mode capable of judging which condition is optimal in a sheet of transfer paper; and sequentially changing image forming process conditions for yellow, magenta, and cyan for each of the plurality of areas, and for each color. And memory means for storing image forming process conditions for image formation of yellow, magenta, and cyan, respectively, so that the color test mode is executed by the control means. For each of the plurality of regions in the one screen, yellow, magenta,
A color image forming apparatus characterized in that a cyan image forming process condition is sequentially changed, the respective colors are combined to form an image, and a plurality of test color images in which a color balance is sequentially changed are formed in one screen. 2. 10. The color test mode, wherein a developing bias control mode in which the developing bias value of each color developing unit is changed by ± 1 step from the reference value in order within one screen is provided. Item). 3. The color test mode is arbitrarily performed by an operation button provided on an operation panel, and the control timing is changed according to a selected paper size. Color image forming apparatus.