JPH083669B2 - Electrostatic transfer recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic transfer recording apparatus, and more particularly to an electrostatic transfer recording apparatus in which an image corresponding to the same original image is recorded plural times to improve density reproducibility in a recorded image. The present invention relates to a transfer type recording device.

2. Description of the Related Art In an electrostatic transfer type recording apparatus, for example, an electrostatic copying apparatus, a series of recording processes such as charging, exposure, development and fixing are performed to record a copy of an original image on a predetermined recording paper. In this case, if the density of the original image and the density of the recorded image are in a proportional relationship, an image faithful to the original image can be reproduced.

Figure 4a shows the relationship between original density and copy density when the developing bias voltage is adjusted, Figure 4b shows the relationship between original density and copy density when the exposure light amount is adjusted, and Figure 4c shows the charging of the photoconductor. 6 is a graph showing the relationship between the document density and the copy density when the voltage is adjusted. As can be seen by referring to these graphs, the relationship between the document density (OD) and the copy density (ID) (hereinafter referred to as the OD-ID characteristic) depends on various parameters related to the recording process (developing bias voltage, exposure light amount, charging voltage). However, it is not possible to obtain a linear OD-ID characteristic over a wide range.

For this reason, in the conventional copying apparatus, in particular, in the color copying apparatus, many parameter adjusting means are provided to adjust various parameters so that the most preferable image can be obtained according to the type of the original image. is there. Therefore, in order to obtain a preferable copy, many test copies must be taken, and even if the adjustment is strictly performed, sufficient image quality can be obtained for a document such as a photograph with a wide density change range. Absent.

In order to improve such inconvenience, several different OD-I
With a D characteristic, a copying apparatus has been proposed in which the above-described recording process is executed a plurality of times for one document and all the images formed in each process are superimposed to make one copy.

See Figure 4d. By adjusting various parameters as described above, a partially linear OD-ID characteristic can be obtained. The curve a shows the OD-ID characteristic which is linear in the high density portion of the document, and the curve b is linear in the low density portion of the document O
The D-ID characteristics are shown respectively, but the image formed by adjusting various parameters to obtain the former characteristic and the image formed by adjusting various parameters to obtain the latter characteristic are superimposed. By making one copy, the relationship between the density of the superposed copy and the density of the original becomes linear in a wide range as represented by the curve c. That is, equivalently,
A copying apparatus having a linear OD-ID characteristic over a wide range can be obtained.

In an electrostatic transfer type color image recording device, for example, an electrostatic transfer type color copying device, the OD-ID of the curve a (or curve b)
Adjusting various parameters so as to obtain the characteristics, performing the recording process for each of the Y (yellow), C (cyan), and M (magenta) components to create an image, the OD of curve b (or curve a) -Adjust various parameters to obtain ID characteristics, and Y (yellow), C (cyan) and M (magenta)
The component-by-component recording process is performed to overlay the imaged images. This allows OD-I for color originals and color copies.
The D characteristic becomes equal to the curve c, and a color image faithful to the original image is reproduced.

By the way, a photoconductor (charge carrier) for forming an electrostatic latent image suffers from a fatigue phenomenon due to the above-mentioned hazards such as charging and exposure, and the surface after being charged and exposed in a plurality of successive recording processes. The electric potential fluctuates. FIG. 4e shows the normalized surface potential in each recording process for a plurality of successive recording processes. Specifically, for example, Y, C,
In a copying apparatus that executes the recording process in the order of M components and repeats it twice (that is, a total of 6 processes) to make one copy, all adjustment parameters regarding the recording process are made equal, Electrostatic charge in each process (indicated by the number of rotations of the photoconductor drum in Figure 4e) when making multiple copies of an original (for example, a gray color patch) that has the same mixture of Y, C, and M components. Consider it to represent the average potential of the latent image.

According to this, the surface potential of the photoconductor becomes high in the first recording process after the rest and becomes substantially the same in the second and subsequent recording processes. This is because the photoconductor converges to a substantially constant fatigue state in the second and subsequent recording processes. Therefore, when the image forming process is repeated in the order of Y, C, and M components, the first copy is a strong copy of yellow (Y) (if the order is different, it is a strong copy of C component or M component). From the second sheet onward, a copy having almost the same color reproduction can be obtained.

In order to solve this, in the conventional copying apparatus, in the first recording process after suspension, the developing bias is set high (the developing potential is lowered) so that the surface potentials of the photoconductors are made equal. ing.

However, there are variations among the photoconductors, and it is difficult to make the color balance of the first copy completely equal to the color balance of the second and subsequent copies by adjusting the developing bias as described above.

Further, if the photoconductor is fatigued due to a change with time, it becomes more difficult to set the color balance, and the color bias may be deteriorated by adjusting the developing bias uniquely.

It is an object of the present invention to reduce the number of images when recording a plurality of continuous images.
To provide an electrostatic transfer recording device in which the difference in image quality between the first recorded image and the second and subsequent recorded images is as small as possible, for example, the first copy and the second copy during continuous copying. A first object of the present invention is to provide an electrostatic transfer type color copying apparatus in which the difference in the color balance of the eye copy is hardly noticeable. In addition to this, a second object is to suppress recording which causes background stains (stain point distribution) in a low-density and low-density portion, such as shadows caused by fine irregularities on a document.

To achieve the above object, in the electrostatic transfer type recording apparatus of the present invention, at least one of the parameters for controlling the electrostatic latent image forming means, the charging means and the developing means is the original parameter. The first parameter that emphasizes the reproducibility of the density of the visible image corresponding to the high density portion of the image, and the second parameter that emphasizes the reproducibility of the density of the visible image corresponding to the low density portion of the original image. Storage means for storing the parameters of the above; a charge carrier is charged through a charging means, an electrostatic latent image forming means, a developing means and a transfer means, and an electrostatic image corresponding to the original image is formed on the charged charge carrier. A recording control unit that executes a recording process of forming a latent image, developing the electrostatic latent image, and transferring the visible image developed by the development to a transfer medium, the recording control unit comprising:
After performing the first recording process based on the parameter of, the second recording process based on the second parameter is performed to obtain a visible image by the first and second recording processes.
A recording control means for superimposing on the transfer medium; and a halftone dot processing means for converting the electrostatic latent image formed by the electrostatic latent image forming means in the second recording process into a halftone dot processing latent image.

Functions and Effects Here, please refer to FIG. 4e again. It is considered that the difference between the surface potential in the first recording process after the pause and the surface potential in the second and subsequent recording processes, which is indicated by Δ in Fig. 4e, is almost constant regardless of the density of the original image. To be Therefore, the fluctuation rate is small when the surface potentials of both are relatively high, and conversely, the fluctuation rate is large when the surface potentials of both are relatively low.

In other words, when reproducing a high-density original image,
The difference in image quality between the first recorded image after the pause and the recorded images after the second pause is hardly noticeable, but conversely, when reproducing a low-density original image, the first recorded image after the pause The difference in image quality between the recorded image of No. 1 and the recorded images of the second time and thereafter becomes large and conspicuous.

In the present invention, first, in the first recording process, the reproducibility of the high density portion of the original image is emphasized in recording, and in the second recording process, the reproducibility of the low density portion of the original image is emphasized. Record and superimpose these images on one (1
Image is produced, it is possible to obtain a recorded image with high reproducibility in both the high density region and the low density region, and the fluctuation of the surface potential of the photoconductor (charge carrier) in the continuous recording process. When the image recording is performed on a plurality of consecutive images, the difference in image quality between the first recorded image and the second and subsequent recorded images becomes almost inconspicuous.

Further, in the present invention, since the halftone dot processing means uses the electrostatic latent image formed by the electrostatic latent image forming means in the second recording process as the halftone dot processed latent image, the recorded image representing the low density area is the halftone dot. It becomes an image. That is, the low-density area image becomes a halftone dot image on one recorded image. As a result, a low-density and low-density portion, such as a shadow that is caused by fine irregularities on the original, is less likely to appear as a background stain point distribution, and the gradation of the image, especially in the low-density area, is reduced. A recorded image with rich tonal expression and little background stain can be obtained.

Other objects and features of the present invention will become apparent from the following description of the embodiments with reference to the drawings.

FIG. 1 shows a mechanical section of one type of color copying apparatus embodying the present invention. A description will be given with reference to FIG.

Reference numeral 1 is a contact glass on which a document is placed, and a pressure plate 2 for adhering a document (not shown) to the contact glass 1 is provided above the contact glass 1. Below the contact glass 1, an optical scanning system having an exposure lamp 3, a first mirror 4, a second mirror 5, a third mirror 6, a lens 7, a fourth mirror 8, a color separation filter 9 and the like is provided. The light emitted from the exposure lamp 3 illuminates the document on the contact glass 1, and the reflected light reflects the first mirror 4, the second mirror 5, the third mirror 6, the lens 7, the fourth mirror 8 and the color separation. The light enters the surface of the photoconductor drum 10 through the filter 9.

The color separation filter 9 has three filter plates of R (red), G (green) and (blue) arranged at an angle of 120 degrees to each other, and one of the filter plates is
It is selectively inserted in the optical path of the optical scanning system. The color separation filter 9 is rotationally driven by a filter motor 175m described later, and the filter plate inserted in the optical path is updated.

By inserting the R, G, and B filter plates in the optical path in sequence and scanning the document, the basic colors of R, G, and B (light 3
The optical image corresponding to the original image decomposed into
The surface of is illuminated and an electrostatic latent image is obtained. In this embodiment, the filter plates are selected in the order of B, R and G. The color separation filter 9 is equipped with a filter position sensor (175s described later) that outputs a detection signal when a blue filter plate is inserted in the optical path.

Around the photosensitive drum 10, a charger (main charger) 11, an eraser 12, a halftone dot unit 13, a magenta (M) developing device 14m, a cyan (C) developing device 14c, and a yellow (Y).
Developing device 14y, pre-transfer charge removing lamp 15, transfer charger 16, pre-cleaning charge removing charger 17, cleaning unit 18,
Equipped with a static eliminator charger 19, a transfer drum 20, and the like.

In the color copying apparatus of the present embodiment, a low-density and low-density portion that is shaded by fine irregularities of the original is faithfully reproduced in the image formation process of the low-density portion, which adversely affects In order to prevent the background stain, the halftone dot unit 13 performs halftone dot processing on the electrostatic latent image in the low density image forming process. A description will be given with reference to FIGS. 2a and 2b.

The halftone dot unit 15 mainly includes a hexagonal column screen SCR extending in the axial direction of the photosensitive drum 10, an illumination unit LED, a condenser lens unit, a screen drive motor MTR, and a screen position sensor SNS.

Of the six sides of the screen SCR, five sides are made of transparent film, and each side has a different 1600dot /
A dot pattern of mm (dots per millimeter) is printed. Figure 3a shows the halftone dot pattern on the first surface
3b shows the halftone dot pattern of the second surface, FIG. 3c shows the halftone dot pattern of the third surface, FIG. 3d shows the halftone dot pattern of the fourth surface, and FIG. 3e shows the halftone dot pattern of the fifth surface. , Respectively (one example).
These halftone dot patterns are printed on each side at a 45 ° angle with the vertical and horizontal alignment of the halftone dot patterns easily noticeable. In this embodiment, the halftone dot pattern on the third surface (Fig. 3c)
Based on the above, a two-step halftone dot pattern is used for smaller dot diameters (second halftone dot pattern, first halftone dot pattern) and two steps for larger dot diameters. (Halftone dot pattern on the fourth surface, halftone dot pattern on the fifth surface) are prepared.

The screen drive motor MTR rotationally drives the screen SCR every 60 °, and the screen position sensor SNS outputs a detection signal when the halftone dot pattern on the third surface is selected.

The lighting unit LED illuminates in four stages from 0 level to 3 level. The 0 level means that the LED is off, that is, there is no halftone processing. The front surface of the lighting unit LED is provided with a diffuser plate so as to evenly illuminate the selected surface of the screen SCR, and the light transmitted through the surface is transmitted through the condenser lens unit LNS to the photosensitive drum 10. The surface is illuminated and a halftone dot pattern is imaged. The irradiation position of the halftone dot pattern is slightly downstream of the exposure position of the optical scanning system. As a result, the portion outside the dots of the halftone dot pattern is exposed and discharged, so that the halftone dot processing is performed on the electrostatic latent image. Is applied.

 Referring back to FIG.

The electrostatic latent image obtained by color-separating the reflected light of the document with the blue filter is color-separated with the green filter in the cyan developer 14c in the yellow developing device 14y, and the electrostatic latent image obtained by color-separating with the red filter in the cyan developing device 14c. The electrostatic latent images thus obtained are each developed in the magenta developing device 14m.

A ring gear (not shown) is provided at one end of each of the photoconductor drum 10 and the transfer drum 20, and they are coupled to each other. The ring gear is connected to a main motor (151 described later) via a transmission mechanism (not shown). First
In the figure, the photosensitive drum 10 rotates counterclockwise and the transfer drum 20 rotates clockwise.

The transfer charger 16 is arranged inside the transfer drum 20 at a position close to the photoconductor drum 10. Transfer drum
The cylindrical portion of 20 which holds the recording sheet is made of a dielectric film (mylar), and comes into contact with the surface of the photosensitive drum 10 through the recording sheet when performing a recording operation. An upper separation charger 21U and a lower separation charger 21D are arranged at positions downstream of the transfer charger 16 of the transfer drum 20 with the peripheral wall of the transfer drum 20 interposed therebetween.

The paper feed system is equipped with two paper feed cassettes 22U and 22D, and one of them is selected to feed paper. Calling rollers 23U, 23D, paper feeding rollers 24U, 24D
Are provided, and by driving these, recording sheets are fed one by one from the upper paper feed cassette 22U or the lower paper feed cassette 22D.

The recording sheet fed from the sheet feeding cassette 22U or 22D is stopped at the position of the registration roller 25 and is fed to the transfer drum 20 at a predetermined timing. The leading edge of the recording sheet is clamped by a clamper (not shown) provided on the outer peripheral surface of the transfer drum 20, and a transfer current is applied to the transfer charger 16 to charge the transfer drum 20. Held on the face. When all the images have been transferred, the charge is removed by applying a predetermined AC voltage to the separation chargers 21U and 21D. At the same time, the clamper is opened, and the separation claw 26 is operated to transfer the recording sheet to the transfer drum 20. Separate from.

The separated recording sheet is sent to the fixing unit 28 located downstream of the conveying belt 27, where it is thermally fixed, and then discharged to the discharge tray 30 via the discharge roller 29.

Operation & display board 200 of the color copying machine shown in FIG.
Is shown in FIG. 5a. Referring to FIG. 5a, this operation board has a print key 201, an interrupt key 202, a numeric keypad 203, a clear / stop key 204, a paper key 205, a magnification key 206, a mode selection key 210, 220, 230, 240 and a mode immediately above each mode selection key. Indicator lamps 211, 221, 231, 241, and indicators
Equipped with 250.

In this example, by operating the mode selection key 210, 220, 230 or 240, the copying process can be executed with five kinds of preset OD-ID characteristics. Immediately after turning on the power of the device, the normal mode is selected, and each mode selection key 210, 220, 23
By pressing 0 or 240, A mode, B mode, C mode or D mode is set, and the indicator lamps 211, 22 immediately above are set.
1,231 or 241 lights up. Also, if you re-operate the key (210, 220, 230 or 240) corresponding to the mode being set,
The mode is released and the normal mode is set. In the normal mode, all the display lamps 211, 221, 231 or 241 are turned off.

In order to set the characteristics of each mode, this color copying machine is equipped with a color balance setting board 300 shown in FIG. 5b. The setting board 300 is located near the operation board 300, but is usually covered with a cover (not shown).

Referring to Figure 5b, this color balance setting board
The 300 has a number of keys and an indicator 370.

The key 310 is for selecting one of the five faces of the screen SCR of the halftone dot unit 13, and the up key (marked with Δ:
The same applies hereinafter) to select a halftone dot pattern with a successively larger dot diameter, and the down key (∇ mark: same applies below) selects a halftone dot pattern with a successively smaller dot diameter. The key 320 is for adjusting the illumination level of the illumination unit LED of the halftone dot unit 13, and is set to a successively higher level (bright) by operating the up key and is set to a lower level (dark) sequentially by operating the down key. It

The six keys 330 are for adjusting (up, down) the developing bias voltage for each of Y, C, and M.
One key 340 is for adjusting the applied voltage (charge level) of the charger 11 for each of Y, C and M, and six keys 350 are for adjusting the exposure level of the exposure lamp 3 to Y, C and M.
It is for adjusting each of the. The developing bias, the charge collecting level and the exposure level can be adjusted in 16 steps, respectively, but steps 0 to 7 mainly correspond to each parameter in the curve b shown in FIG. Mainly corresponds to each parameter in the curve a shown in FIG. 4d.

The key 360 is a memory-in key for storing the value updated by the keys 330, 340, and 350 in the setting mode memory.

The display unit 370 is equipped with 11 7-segment numeric display units just above each key. The screen of dot pattern, LED illumination level, and 9 parameters, that is, Y, C, M development bias , Y, C, M charge level, Y, C, M exposure level,
A display digit is assigned to each. The 16 steps of development bias, charging level and exposure level are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F. Displayed in each display digit.

FIG. 6 shows an outline of the electric circuit configuration of the color copying machine shown in FIG. Referring to FIG. 6, the control system of this device is mainly constructed by the main control board 100. Inside the main control board 100, the microprocessor (MPU) 101, RO
M (read only memory) 102, RAM (read / write memory) 10
3, NRAM (read-write non-volatile memory) 104, and NRAM
The backup circuit 105 of 104 and the like are provided. NRAM104
Is provided to store data that needs to be retained even when the power of the apparatus is cut off, for example, the values of various parameters set by the color balance setting board 300.

The input / output interface 110 includes a charging power pack (PP) 111, a static elimination power pack 112, and a separation power pack 11
3, The eraser 12 and the halftone dot unit 13 are connected.

The charging power pack 111 includes a 6-bit charging control signal from the main control board 100, a 4-bit transfer control signal, and a 5-bit transfer control signal.
Predetermined power is supplied to the charging charger 11, the transfer charger 16 and the developing bias voltage output line (not shown) based on the bit developing bias control signal.

The charge removal power pack 112 applies a predetermined charge removal voltage to the pre-cleaning charge removal charger 17 and the charge removal charger 19 in response to the charge removal charger ON signal from the main control board 100.

The separation power pack 113, in response to the separation charger ON signal from the main control board 100, the upper separation charger 21U.
And a predetermined separation voltage is applied to the lower separation charger 21D. In this example, the separation charger ON signal has 2 bits, and the separation voltage can be switched between AC 5.5KV and AC 4KV. When a voltage of 4 KV is applied, sufficient charge removal is not performed, so the recording sheet does not peel from the transfer drum (intermediate charge removal described below).

I / O interface 120 has operation & display board 2
00 and the color balance setting board 300 are connected.

A paper feeding control unit is connected to the input / output interface 130. The control unit includes an upper sheet feeding system registration detection sensor 131U, a paper end sensor 132U, a sheet size sensor 133U, and a lower sheet feeding system registration detection sensor 131D, a paper end sensor 132D, a sheet size sensor 13U.
3D, etc., and the stepping motor driver 134 and the registration motor 135 connected to the driver 134,
The sheet feeding motor 136 and the sheet feeding table motor 137 are included.

To the input / output interface 140, a control unit for each developing system of Y, C, M is connected. This control unit
Toner concentration is automatically adjusted in each of the developing devices 14y, 14c, 14m.

The input / output interface 150 includes a heater of the fixing unit 28, a main motor 151, and various fan motors 152, 1
An AC unit 160 including 53 etc. is connected.

A lamp regulator 161 for adjusting the exposure level of the exposure lamp 3 is connected to the input / output interface 160.

The input / output interface 170 drives the positions of the cleaning motor 171m for driving the cleaning unit 20, the return motor 172m for returning the optical scanning system (scanner), the clamp motor 173m for opening / closing the clamper, and the lens 7. A lens motor 174m for controlling the copy magnification, a filter motor 175m for driving the color separation filter 9, and position sensors 171s, 172s, 173s, 174s and 175s of a mechanism driven by each motor are connected.

Next, the operation of the color copying apparatus shown in FIG. 1 will be described. First, a characteristic part will be briefly described. In this example, in the normal mode, the A mode, the B mode, and the C mode, the image forming and transferring processes are performed once for each of the Y, C, and M colors, but in the D mode, the C forming process is performed.
Y, C, M according to mode characteristics (set parameters)
After performing each of the image formation and transfer processes of
In accordance with the characteristics of B mode, and after performing halftone dot processing, Y,
Each process of image formation and transfer of C and M is performed once.
As will be made clear in the following description, in the B mode, the reproducibility of the portion where the original density is relatively low is emphasized, and the C
Since the mode emphasizes the reproducibility of the area where the original density is relatively high, the curve b shown in FIG. 4d is set to the B mode, and the curve a is set to the C mode. Recording can be performed with the characteristic of c.

FIG. 7 shows an outline of the operation of the copying machine shown in FIG. Seventh
It will be described with reference to the drawings. When the power is turned on, first the initial settings are made. Specifically, after setting the output port to the initial state and clearing the internal memory, the positions of the movable parts such as the scanner, the lens 7, the color separation filter 9, the screen SCR of the halftone dot unit 13 are set to the initial state (home position). And accordingly, the register for storing the value corresponding to the position of the movable portion is set to the reference value, and each control unit is set to the operable state. The normal mode is selected as the operation mode. Details of the normal mode will be described later. At this time, the illumination unit LED of the halftone dot unit 13 is set to level 2. After the initial setting, the status of each part (fixing temperature, etc.) is repeatedly checked, and if there is an abnormality, abnormal processing is performed. If there is no abnormality, the status of each part is checked, key input processing, etc. are repeatedly executed, and operation becomes possible. Wait for When the operation preparation is completed (Ready), the operation &
“Copy permitted” is displayed on the display 250 of the display board 200, and the above processing is repeatedly executed until the print key 2101 is pressed.

The "key input processing" subroutine is shown in Figs. 8a, 8b,
Shown in Figures 8c and 8d. The "key input process" will be described with reference to the drawings. In this subroutine, the presence / absence of a key input is checked, and if there is a key input, the corresponding processing is performed. The key-on flag is a flag for detecting the start of a key operation. As will be described later, this flag is set when the same key is continuously operated, so that the key input is not read. Also, this flag is reset when there is no key input.

When the print key 201 is turned on, the start flag is set.

When the numeric keypad 203 or the clear / stop key 204 is turned on, the number of copies is set according to the key operation, and when the paper key 205 is turned on, the paper feed system selected at the time of copy operation is switched from the upper stage to the lower stage or from the lower stage to the upper stage. When the magnification key 206 is turned on, the magnification control is performed to switch the magnification, and then the key-on flag is set and the corresponding display is performed (Fig. 8d), and the process returns to the main routine shown in Fig. 7.

Next, the processing of the keys related to the density parameter will be described, but before that, the configuration of the memory for storing each parameter will be described. Referring to the memory map shown in FIG. 17,
The memory block consisting of a part of RAM103 and a part of NRAM104 has memory MI1, MI2, M for each color of Y, C, M.
I3, MN1, MN2, MN3, MA1, MA2, MA3, MB1, MB2, MB3, MC1, MC2, MC
It has memory areas corresponding to 3, MD1, MD2 and MD3. The data being input is stored in the memories MI1 to MI3.
Normal mode data for MN1 to MN3, A mode data for MA1 to MA3, B mode data for MB1 to MB3, C mode data for MC1 to MC3, and MD1 to M
D mode data is stored in D3. The data stored in the memories MI1, MN1, MA1, MB1, MC1 and MD1 is used as a parameter for adjusting the developing bias voltage.
The data stored in MN2, MA2, MB2, MC2 and MD2 are stored in the memory MI3, MN3, MA3, MB3,
The data stored in MC3 and MD3 respectively correspond to the parameters for adjusting the exposure level.

Referring again to FIG. 8a, the mode selection keys 210, 220, 23
When 0 or 240 is turned on, the following processing is performed in response to the pressed mode key.

When the mode key 210 is turned on, the mode register RG becomes 1
If not, the register RG is set to 1, and the memory MA1,
The contents of MA2 and MA3 are stored in memories MI1, MI2 and MI3, respectively.
If the register RG is 1, the register RG is set to 0, and the contents of the memories MN1, MN2 and MN3 are stored in the memories MI1, MI2 and MI3, respectively, and stored in the normal mode. Set the mode.

When the mode key 220 is turned on, the mode register RG becomes 2
If not, 2 is set in the register RG and the memory MB1,
The contents of MB2 and MB3 are stored in memories MI1, MI2 and MI3, respectively.
When the register RG is 2, the normal mode is set as described above. Mode key
When 230 is turned on, if mode register RG is not 3,
Set 3 in the register RG and set the memory MC1, MC2 and MC3
Contents of memory C in memory MI1, MI2 and MI3 respectively.
When the mode is set and the register RG is 3, the normal mode is set as described above. When the mode key 240 is turned on, if the mode register RG is not 4, the register RG
Is set to 4, the contents of the memories MD1, MD2 and MD3 are stored in the memories MI1, MI2 and MI3, respectively, to set the D mode, and if the register RG is 4, the normal mode is set as described above. Then, the key-on flag is set and the corresponding display is performed (Fig. 8d), and the process returns to the main routine shown in Fig. 7.

That is, the mode register RG represents the mode being set, and the mode keys 210, 220, 230 different from the mode being set are set.
Or when 240 is operated, the mode corresponding to the operation key is updated and set, and the mode key 210, 220, 23 equal to the mode being set is set.
When 0 or 240 is operated, the normal mode is updated and set, and the parameters of each mode are transferred to the memories MI1, MI2 and MI3.

Referring to FIG. 8b, color balance setting board 300
When the key 310 is operated, the following processing is performed. Since the key 310 is a key switch for selecting the surface of the screen SCR of the halftone dot unit 13 for performing halftone dot processing in the D mode, the mode register RG is selected. If is not 4, this key operation is canceled.

When the down key (∇ mark) is operated, the pattern register RP is checked, and if the register RP is not 1, decrement by 1 (-1), and the screen drive motor MTR is energized by 60 ° in the reverse direction so that the dot is formed. Select faces with smaller dot patterns. Regarding the value of the pattern register RP, 1 is the selection of the first surface (the halftone dot pattern shown in FIG. 3a is printed), 2
Is the selection of the second surface (the dot pattern shown in FIG. 3b is printed), 3 is the selection of the third surface (the dot pattern shown in FIG. 3c is printed), and 4 is the Register 4 because it means the selection of 4th surface (the halftone dot pattern shown in Fig. 3d is printed) and 5 means the selection of the 5th surface (the halftone dot pattern shown in Fig. 3e is printed). If the value becomes 3 when the RP is decremented by 1, the reverse positioning of the MTR is performed while monitoring the SNS, and home positioning is performed.
Also, the screen with the smallest dot diameter of the halftone dot pattern
If the down key is further operated while the first surface of SCR is selected (RP = 1), halftone dot processing without dots, that is, full erase of the electrostatic latent image according to the characteristics of B mode is performed. Then, the mode register RG is set to 3, the D mode is released and the C mode is set (see FIG. 8a).

If it is the up key (marked with Δ), the pattern register RP is adjusted, and if the register RP is not 5, it is incremented by 1 (+1) and the screen drive motor MTR is biased by 60 ° in the forward direction. Also in this case, when the value becomes 3 when the register RP is incremented by 1, the reverse rotation of the MTR is performed while monitoring the SNS to perform home positioning. After the setting corresponding to the key operation is performed, the key-on flag is set and the corresponding display is performed (Fig. 8d), and the process returns to the main routine shown in Fig. 7.

If the D mode is set (RG = 4) when the key 320 of the color balance setting board 300 is operated, the halftone dot unit 13
Update the lighting level of the lighting unit LED of. The lighting level and the value of the lighting register RL are in correspondence, and when the down key (marked with ▽) is operated, the register RL is decremented by 1 and when the up key (marked with △) is operated, the register RL is decremented. Increment by 1. However, since the illumination level has four levels from 0 level (extinction) to 3 levels (the brightest) as described above, the illumination register RL is 0.
If so, the operation of the down key is canceled, and if the illumination register RL is 3, the operation of the up key is canceled.
After making the settings corresponding to these key operations, set the key-on flag and display the corresponding display (8d).
FIG.), And returns to the main routine shown in FIG.

Referring to FIG. 8c, color balance setting board 300
When the key 330 of (one of the 6 keys) is turned on,
Whether it is the up key (marked with △) or the down key (marked with ▽) is determined, and if it is the down key, the contents of memory MI1 (only the one corresponding to the turned-on key among Y, C, and M) is written. Decrement by one (-1). However, as described above, the contents of the memory MI1 correspond to the parameters for adjusting the developing bias. In particular, 0 to 7 are the parameters in the curve b shown in FIG. 4d, and 8 to 15 are the parameters shown in FIG. 4d. Since it mainly corresponds to the parameter in the curve a, the content of the memory MI1 before the update is 8 when the C mode is set (RG = 3) in which importance is attached to the reproducibility of the portion where the document density is relatively high. If the contents of the memory MI1 before updating are 0, the updating is not performed in other modes.

If it is an up key, the content of the memory MI1 (only the one corresponding to the turned-on key among Y, C, and M) is incremented by 1 (+1). However, when the B mode that emphasizes the reproducibility of the portion where the document density is relatively low is set (RG = 2), if the content of the memory MI1 before the update is 7, the update is not performed, and in other modes. Memory before update MI1
If the content of is 15, it will not be updated.

Regardless of which key operation is performed, the key-on flag is set and the corresponding display is performed (8d).
FIG. 7), the main routine shown in FIG. 7 is returned.

When the key 340 (one of the 6 keys) on the color balance setting board 300 is turned on, it is determined whether the key is an up key (△ mark) or a down key (▽ mark). Decrement (-1) the content of MI2 (only the one corresponding to the turned-on key among Y, C, M).
However, as described above, the contents of the memory MI2 correspond to the parameters for adjusting the charging level, and particularly 0 to 7 are the 4th d.
8 to 15 are assigned to the parameter in the curve b shown in the figure.
Since it mainly corresponds to the parameter in the curve a shown in FIG. 4d, the contents of the memory MI2 before update are set when the C mode is set (RG = 3), which emphasizes the reproducibility of the portion where the document density is relatively high. If the value is 8, the update is not performed. In other modes, if the content of the memory MI2 before the update is 0, the update is not performed.

If it is an up key, the content of the memory MI2 (only the one corresponding to the turned-on key among Y, C, and M) is incremented by 1 (+1). However, when the B mode that emphasizes the reproducibility of the portion where the original density is relatively low is set (RG = 2), if the content of the memory MI2 before the update is 7, the update is not performed, and in other modes. Memory MI2 before update
If the content of 5 is 5, the update is not performed.

Whichever key is operated, the key-on flag is then set and the corresponding display is performed (Fig. 8d), and the process returns to the main routine shown in Fig. 7.

When the key 350 (one of the six keys) of the color balance setting board 300 is turned on, it is determined whether the key is the up key (△ mark) or the down key (▽ mark). Decrement (-1) the content of MI3 (only the one corresponding to the turned-on key among Y, C, M).
However, as described above, the content of the memory MI3 corresponds to the parameter for adjusting the strong light level, and in particular, 0 to 7 are the 4th d.
8 to 15 are assigned to the parameter in the curve b shown in the figure.
Since it mainly corresponds to the parameter in the curve a shown in FIG. 4d, the contents of the memory MI3 before update are set when the C mode is set (RG = 3), which emphasizes the reproducibility of the portion where the document density is relatively high. If the value is 8, the update is not performed. In other modes, if the content of the memory MI3 before the update is 0, the update is not performed.

If it is an up key, the content of the memory MI3 (only the one corresponding to the turned-on key among Y, C, and M) is incremented by 1 (+1). However, when the B mode that places importance on the reproducibility of the portion where the original density is relatively low is set (RG = 2), if the content of the memory MI3 before the update is 7, the update is not performed, and in other modes. Memory MI3 before update
If the content of is 15, it will not be updated.

Regardless of which key operation is performed, the key-on flag is then set and the corresponding display is performed (No.
8d), and returns to the main routine shown in FIG.

Referring to FIG. 8d, color balance setting board 300
Memory ink-360 turns on, the mode register R
Refer to the contents of G.

Since RG = 0 is the normal mode, memories MI1 and MI2
And the contents of MI3 are stored in the corresponding memories MN1, MN2, and MN3, respectively, and if RG = 1, it means the A mode,
The contents of the memories MI1, MI2, and MI3 are stored in the corresponding memories MA1, MA2, and MA3, and if RG = 2, the B mode is selected. Therefore, the contents of the memories MI1, MI2, and MI3 are stored in the corresponding memories MB1, MB2. And in MB3, and if RG = 3, it is in C mode, so the contents of memories MI1, MI2, and MI3 are stored in corresponding memories MC1, MC2, and MC3, respectively, and if RG = 4, it is in D mode. So the memory MI1, MI
The contents of 2 and MI3 are stored in the corresponding memories MD1, MD2 and MD3, respectively. Thereafter, the key-on flag is set, the corresponding display is performed, and the process returns to the main routine shown in FIG.

That is, each parameter of the mode selected by operating the mode selection key 210, 220, 230 or 240 is read from the NRAM 104 and transferred to the memories MI1, MI2 and MI3, and the value of the memory is updated by operating the key 330, 340 or 350. The updated value is stored in the corresponding area of the setting mode of the NRAM 104 again by operating the memory in key 360. As described above, when the A mode, B mode, C mode, or D mode is set, the display lamp 211, 221, 231, or 241 immediately above the selection key 210, 220, 230, or 240 is lit up, and when the normal mode is set, either The display lamp also goes off.

Further, as described above, in the D mode, the first process (Y, C, and M each time) is executed with each parameter of the B mode, and subsequently, the second process (Y with each parameter of the C mode is executed. , C, M each time) is executed, each parameter of the B mode and each parameter of the C mode are respectively updated to change each parameter of the first process of the D mode to the second process. Each parameter of can be adjusted independently. As a result, the degree of freedom in adjusting the OD-ID characteristics (original density-copy density) in the D mode is increased.

When a key operation other than the above is performed, the corresponding process is performed, the key-on flag is set, the corresponding display is performed, and the process returns to the main routine shown in FIG.

If there is no key operation, the key-on flag is reset if it is set, and the start flag is reset if it is set (see the main routine shown in FIG. As described above, the start flag is present and the key operation is not performed is limited to the loop waiting for the operation preparation), and after the predetermined display is performed, the process returns to the main routine shown in FIG.

Referring back to FIG. When the print key 201 is operated, the print start flag is set in the "key input process". Therefore, the start flag and the key-on flag are reset and the "register set" is performed.
After executing the subroutine, start the copy process. In the copy process, "charge control", "scanner control", "exposure control", "halftone dot control", "developing bias control", "transfer control" and "separation control" subroutines, and other controls Repeatedly executed in a short cycle until copying is completed.

First, the "register set" subroutine will be described with reference to FIG. In this, the values of counters CN1, CN2, CN3, CN4, CN5, CN6 and CN7 and the values of registers R1, R2, R3, R1 ', R2' and R3 'used in the copy process described below are set. ing.

In the copy process other than D mode (RG = 4), Y, C, M
Since the image forming and transfer processes are performed once, that is, three times in total, the values of the counters CN1 to CN5 are set to 3, and the values of the counters CN6 and CN7 are set to 1.
In this case, the memories MI1, MI2 and MI3 store parameters (1 of 16 steps each) for adjusting the developing bias voltage, the charging level and the exposure level in the normal mode, A mode, B mode or C mode. Therefore, the value of the memory MI1 is set in the register R1, the value of the memory MI2 is set in the register R2, the value of the memory MI3 is set in the register R3, and the process returns to the main routine.

In the D mode copy process, Y, C, and M are each 2
Since the image forming and transferring processes are performed once, that is, six times in total, the values of the counters CN1 to CN5 are set to 6, and the values of the counters CN6 and CN7 are set to 1. After that, the parameters (1 of 16 steps each) for adjusting the developing bias voltage, the charging level and the exposure level in the first process are set in the registers R1, R2 and R3, respectively, and the registers R1 ′, R2 ′ and R3 are set. The parameters for adjusting the developing bias voltage, the charging level and the exposure level in the second process are set in ′.

In the D mode, the memories MI1, MI2 and MI3 store values for increasing and decreasing the parameters for adjusting the developing bias voltage, the charging level and the exposure level in the B mode and the C mode. These values are 8
As the reference, the value obtained by adding the deviation (MI1-8) of the value of the memory MI1 to the memory MC1 to the register R1 is added to the register R1 and the deviation of the value of the memory MI2 to the memory MC2 from 8 to the register R2 (MI2-8). Is added to the register R3 by adding the deviation (MI3-8) of the value of the memory MI3 to the memory MC3 to 8 and the value of the register R1 'to the deviation of the value of the memory MI1 from 8 to the memory MI1 (MI1-8 ) Is added to the register R2 ′ and the deviation (MI2-8) of the value of the memory MI2 in the memory MB2 is set to 8 and the deviation of the value of the memory MI3 to 8 in the memory MB3 is added to the register R3 ′ (MI3 -8) is added to each value. However, as described above, in the D mode, the first process is performed by emphasizing the reproducibility of the portion having a relatively high document density, and the second process is performed by emphasizing the reproducibility of the portion having a relatively low document density. Register R1, R2 and R
Modify the value of 3 to be in the range of 8 to 15, and register R
The values of 1 ', R2' and R3 'are modified to be in the range of 0-7. That is, if the B mode and C mode parameters are properly set in advance, the combined OD-ID characteristic can be shifted by the D mode parameter.
This facilitates adjustment and reduces the number of test copies.

Although not shown here because the same thing is repeated, it goes without saying that registers R1, R2, R3, R
1 ', R2', and R3 'also correspond to Y, C, and M respectively. In the above "register set" subroutine, each parameter is set individually in the register for each Y, C, M. I want you to understand.

The "charge control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN1 is 1 or more, at the charging start timing in the copying process of processing in the loop, the charging charger 11 is provided with the register R2.
Voltage (value corresponding to any of Y, C, and M) is applied, and when time passes and the charging end timing is reached, the voltage application to the charger 11 is released and the counter CN1 value Decrement by 1. That is, the counter CN1 is decremented by 1 each time the charging control of each of Y, C, and M is completed, so that the value of the counter CN1 is set to 3 in the normal mode, A mode, B mode, or C mode for three times. The charging charger 11 is energized, and in the D mode in which the value of the counter CN1 is set to 6, the charging charger 11 is energized six times. Further, in the D mode, since the charging level is different between the first process and the second process, when the charging of the charging charger 11 for three times is completed (CN = 4: before updating), the register R2 ′ is changed. The value of is loaded into register R2.

The "scanner control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN2 is 1 or more, at the start timing of the scanner in the copying process for processing in the loop, the main motor 15
The scanner is driven by 1 to start forward scanning. When the scanning end timing is reached after a further lapse of time, the forward scanning of the scanner is stopped and the return drive of the scanner is started by the return motor 172m. When the scanner reciprocates, the drive system of the main motor 151 or the return motor 172
A drive system of m is selectively connected to the scanner by a clutch (not shown).

When the position sensor 172s of the scanner detects the home position, the return drive is stopped and the value of the counter CN2 is decremented by 1. In other words, the counter CN2 is decremented by 1 each time the scanner control of each of Y, C, and M is completed, so that the value of the counter CN2 is set to 3 in the normal mode, A mode, B mode, or C mode for three times. In the D mode in which the document is scanned and the value of the counter CN2 is set to 6, the document is scanned six times.

The "exposure control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN3 is 1 or more, the exposure lamp 3 corresponds to any one of the values (Y, C, M) of the register R3 at the exposure start timing in the copy process for processing in the loop shape. The exposure lamp 3 is deenergized and the value of the counter CN3 is decremented by 1 at the exposure end timing after a lapse of time. In other words, the counter CN3 is decremented by 1 each time the exposure control for each of Y, C, and M is completed.
In normal mode, A mode, B mode or C mode in which the value of N3 is set to 3, exposure energization for three times is performed,
In the D mode in which the value of the counter CN3 is set to 6, the exposure energization for 6 times is performed.

In this exposure bias, since the color separation filter 9 is inserted in the optical path in the order of B, R, and G, the filter motor 175m is forwardly biased and the filter 9 is rotated by 120 ° at the end of each exposure. Although (the blue filter is initially set),
Each time the blue filter is set, the position sensor 175s performs accurate positioning.

Further, in the D mode, since the charging level is different between the first process and the second process, when the exposure energization for three times is completed (CN = 4: before updating), the value of the register R3 ′ is changed. Loading into register R3.

The "halftone dot control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN6 is 4 or more and the value of the illumination register RL is not 0 (does not light), at the irradiation timing of the halftone dot pattern in the copy process which is processed in the loop, The illumination unit LED of the unit 13 is energized in accordance with the value of the register RL, and when the irradiation end timing comes after a further elapse of time, the LED is deenergized and the value of the counter CN6 is incremented by 1. Counter CN6 is set to 1 in the "register set" subroutine, so in normal mode, A mode, B mode or C mode, this "halftone dot control" subroutine is pass-through, and in D mode it is 3 in the second process. The halftone dot processing (one time for each of Y, C and M) is performed.

The "development bias control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN4 is 1 or more, the value of the register R1 (any one of Y, C, and M) is applied to the developing electrode at the application timing of the developing bias voltage in the copy process of processing in the loop shape. Corresponding to the value), and when the time has passed and the application end timing is reached, the application of the voltage is released and the value of the counter CN4 is decremented by one. That is, the counter CN4 is decremented by 1 each time the charging control of each of Y, C, and M is completed, so that the value of the counter CN4 is set to 3 in the normal mode, A mode, B mode, or C mode for three times. The development bias voltage is applied and the counter
In the D mode in which the value of CN4 is set to 6, the developing bias voltage is applied six times. In the D mode, the developing bias voltage to be applied is different between the first process and the second process, so when the application of the voltage for three times is completed (CN4 = 4: before updating), the register R1 The value of'is loaded into register R1.

The "transfer control" subroutine will be described with reference to FIG. In this case, if the value of the counter CN5 is 1 or more, the current value of the transfer charger 16 is switched according to the value of the counter CN7 at the current switching timing in the copy process for processing in the loop shape, and the counter CN5's value is changed. The value is decremented by 1, and the value of the counter CN7 is incremented by 1. Since the counter CN7 is initially set to 1 in the "register set" subroutine, the number of times of switching is counted.

Normal mode in which the value of counter CN6 is set to 3, A
In the mode, B mode or C mode, the current value of the transfer charger 16 is switched three times, and in the D mode in which the value of the counter CN6 is set to 6, the current value of the transfer charger 16 is switched six times. .

In this embodiment, the energizing current of the transfer charger 16 is set as follows, and the transfer drum 20 is set by repeating the transfer process.
Prevents the transfer efficiency from being lowered due to charging.

1st (Y) ・ ・ ・ 150μA 2nd (C) ・ ・ ・ 250μA 3rd (M) ・ ・ ・ 400μA 4th (Y) ・ ・ ・ 250μA 5th (C) ・ ・ ・ 400μA 6th (M) ... 600 μA As described above, the current is switched six times in the D mode, but in the present embodiment, since intermediate charge removal is performed after the third transfer process as described below,
The transfer current for the fourth time is set to a value smaller than the transfer current for the third time.

The "separation control" subroutine will be described with reference to FIG. When the transfer process is executed, the surface of the transfer drum 20 is charged to the following potential.

1st time ・ ・ ・ About 500V 2nd time ・ ・ ・ 1000 to 1500V 3rd time ・ ・ ・ 2000 to 3000V In the D mode, the transfer process is performed 3 more times, so it will be charged to a higher potential, but this implementation In the "separation control" subroutine of the example, when the third transfer process is completed, an AC voltage of 4 KV is applied between the upper separation charger 21U and the lower separation charger 21D to transfer the transfer drum 20.
Is being neutralized (intermediate static elimination). By performing this intermediate charge removal, the surface potential of the transfer drum 20 is reduced to 500 V to 1000 V, so that the transfer current after that can be smaller than that without the intermediate charge removal. In addition, the intermediate charge is removed from the transfer drum
The recording sheet is not peeled off from the transfer drum 20 because it is not completely discharged.

When peeling the recording sheet from the transfer drum 20, 5.5K is placed between the upper separation charger 21U and the lower separation charger 21D.
By applying an AC voltage of V, the transfer drum 20 is completely neutralized (surface potential 0V).

Therefore, as shown in FIG. 16, in the “separation control” subroutine, when the intermediate charge removal timing is reached, a 4 KV voltage is applied between the upper separation charger 21U and the lower separation charger 21D (only indicated as 21 in FIG. 16). An AC voltage is applied, and at the separation timing, an AC voltage of 5.5 KV is applied between the upper separation charger 21U and the lower separation charger 21D, and the voltage is released at the voltage release timing.

The color copying machine of this embodiment shown in FIG.
It is also possible to make a single color copy of any one of the above (single color mode), but the description of this will be omitted because it is repeated above. Also in this single color mode, four modes of normal mode, A mode, B mode, C mode and D mode can be set as in the above.

In the above embodiment, the color copying machine using three colors of yellow, cyan and magenta has been described, but the present invention is not intended to be limited to this, and color copying using four colors including black is included in this. It may also be suitable for equipment, or for black and white copying using only one black color. Further, although the exposure level is changed according to the light amount of the exposure lamp 3 in the above-described embodiment, the exposure level may be adjusted by providing the lens 7 with a diaphragm, for example.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of a mechanical portion of a color copying apparatus according to an embodiment. 2a and 2b are a sectional view and a perspective view showing the details of the halftone dot unit 13 of the apparatus shown in FIG. 3a, 3b, 3c, 3d and 3e are planes showing halftone dot patterns printed on each surface of the screen SCR of the halftone dot unit 13 shown in FIGS. 2a and 2b. It is a figure. FIGS. 4a, 4b and 4c are graphs showing the relationship between the original density and the copy density when the developing bias voltage, the exposure amount and the charging voltage are changed, and FIG. 4d is the original density in the overlaid copy. And FIG. 4e is a graph showing the normalized surface potential of the photoconductor in each of a plurality of continuous recording processes. 5a and 5b are plan views showing appearances of the operation & display board 200 and the color balance setting board 300 of the apparatus shown in FIG. FIG. 6 is a block diagram showing an electric circuit configuration of the device shown in FIG. Fig. 7, Fig. 8a, Fig. 8b, Fig. 8c, Fig. 8d, Fig. 9, Fig.
FIG. 10, FIG. 11, FIG. 12, FIG. 13, FIG. 13, FIG. 14, FIG. 15 and FIG. 16 are flowcharts showing the schematic operation of the apparatus shown in FIG. FIG. 17 is a memory map showing a part of allocation of each memory of the RAM 103 and the NRAM 104 shown in FIG. 1: Contact glass, 2: Pressure plate 3: Exposure lamp, 4: First mirror 5: Second mirror, 6: Third mirror 8: Fourth mirror, 7: Lens 9: Color separation filter (color separation means) 3, 4,5,6,7,8,9: (electrostatic latent image forming means) 10: photoconductor drum (charge carrier) 11: charging charger (charging means) 12: eraser, 13: halftone dot unit 14m, 14c , 14y: Developing device (developing means) 15: Pre-transfer charge erasing lamp 16: Transfer charger 17: Before cleaning charge erasing charger 18: Cleaning unit 19: Charge removing charger, 20: Transfer drum 16, 20: (transfer means) 21U, 21D: Separation charger 22U, 22D: Paper feed cassette 23U, 23D: Call roller 24U, 24D: Paper feed roller, 25: Registration roller 26: Separation claw, 27: Conveyor belt 28: Fixing unit, 29: Paper ejection roller 30: Paper ejection Tray 100: Main control board (recording control means, storage means) 101: Microprocessor 102: ROM, 103: RAM 104: Non-volatile memory 105: Backup circuit 106: Battery 110, 120, 130, 140, 150, 160, 170: I / O interface circuit 111: Charging power pack 112: Static elimination power pack 113: Separation power pack 151: Main motor, 152, 153: Fan motor 161: Lamp regulator 171m: Cleaning motor 172m: Return motor 173m: Clamp motor 174m : Lens motor 175m: Filter motor 171s, 172s, 173s, 174s, 175s: Position sensor 200: Operation & display board 201: Print key, 202: Interrupt key 203: Numeric keypad, 250,370: Display unit 204: Clear / Stop key 205 : Paper key, 206: Magnification key 210,220,230,240: Mode selection key 211,221,231,241: Mode display lamp 300: Color balance setting board 310: Halftone dot pattern selection key 320: Lighting level setting key 330,340,350: Mode selection key 360: Memory in key SCR: Screen, LED: Lighting unit MTR: Screen drive motor SNS: Screen position sensor

Claims (8)

[Claims] 1. A charge carrier; means for charging the charge carrier; means for forming an electrostatic latent image corresponding to an original image on the charged charge carrier; electrostatic latent formed on the charge carrier A means for developing an image; a means for transferring a visible image developed by development onto a transfer medium; a parameter for controlling at least one of the charging means, the electrostatic latent image forming means and the developing means, A first parameter that emphasizes the reproducibility of the density of the visible image corresponding to the high density portion of the image, and a first parameter that emphasizes the reproducibility of the density of the visible image corresponding to the low density portion of the original image. Storage means for storing two parameters; the charge carrier is charged through the charging means, the electrostatic latent image forming means, the developing means and the transfer means and corresponds to the original image on the charged charge carrier. Form an electrostatic latent image and develop the electrostatic latent image Recording control means for executing a recording process for transferring a visible image developed by development onto a transfer medium, the recording control device executing a first recording process based on the first parameter and then performing a recording process based on the second parameter. A second recording process is performed to superimpose the visible images of the first and second recording processes on the transfer medium; and a recording control unit; and an electrostatic latent image forming unit in the second recording process. An electrostatic transfer recording device comprising: a halftone dot processing means for converting the electrostatic latent image into a halftone dot processing latent image. 2. The electrostatic latent image forming means is an exposure static eliminator which irradiates a charged charge carrier with light representing an image to expose and charge the charge carrier. The electrostatic transfer recording device according to the item (1). 3. The electrostatic latent image forming means has a color separation means for separating an original image into a plurality of color components; and the developing means has a developer of a color corresponding to each color component. The electrostatic transfer recording apparatus according to item (2). 4. The recording control means controls the charging means, the electrostatic latent image forming means, the developing means and the transfer means to charge the charge carrier in one recording process and charge the charged carrier. An electrostatic latent image corresponding to one of the color components of the original image is formed thereon, the electrostatic latent image is visualized with a corresponding developer, and the visible image is transferred to a transfer medium. The electrostatic transfer recording apparatus according to item (3). 5. The recording control means executes the first recording process for each color component, and then executes the second recording process for each color component to obtain a visible image corresponding to each color component by the first recording process. The electrostatic transfer recording apparatus according to claim 4, wherein the visible images corresponding to the respective components in the second recording process are all superposed on the transfer medium. 6. The electrostatic transfer recording apparatus according to claim 3, wherein the plurality of color components are a yellow color component, a cyan color component and a magenta color component. 7. The halftone dot processing means selects one of a plurality of types of halftone dot patterns and sets the electrostatic latent image formed by the electrostatic latent image forming means as a halftone dot processing latent image corresponding to the selected pattern. The electrostatic transfer recording device according to claim 1. 8. The static dot processing method according to claim 7, wherein the halftone dot processing means selects the halftone dot pattern designated by the input means for designating one of a plurality of types of halftone dot patterns. Electro-transfer type recording device.